Jump to content
Sign in to follow this  
Lawsy

So I've begun rebuilding a Fighter Buggy RX from my childhood...

Recommended Posts

As a long time lurker, I might as well make up for it by posting a novel as my first post. Because that always goes down well with the regulars.......

So I've recently had a son, and one of the first things I said to the wife when we found out we were having a boy was "You know he's going to need a build-it-yourself remote control car." She laughed, as did I, except I was laughing because she didn't know that I had a nearly 20 year old fighter buggy lurking in the darkest corners of my parents house. A few drives out to my parents, with a flash light in hand, and I finally found a banged up DT-01 Fighter Buggy, missing its gearbox.... But still had wheels? Hmmm.

So let the Ebaying begin.

  • The gearbox was a steal (about $20 aussie including the spur gear and differential case)
  • A new Sports Tuned that I paid too much for (because I hadn't yet discovered Banzai)
  • The metal parts bag for diff gears and random missing bits that I probably paid too much for as well
  • Some cheap ball bearings (10x 1150 + 1x 850) for $8 delivered; incredible!
  • A cheap FLOUREON 3500mAh battery + Charger (I'm astounded at how good this battery actually is, though the charger is already stuffed after 7 charges..) - for some reason I received this ebay voucher thing for express delivery and $20 off on this one, no idea why.
  • Just yesterday I received a $17.03, 3 mode ESC, and it has blown my mind!
  • Some on-road wheels and tyres - still 2 weeks away and it was one of the first things ordered. It's coming from somewhere in China that requires a horse drawn cart to pick up the post.

So after all of that, here's the result!

Now working1.jpg

No I didn't take progress shots unfortunately, though they wouldn't have been very interesting...

Now this buggy has had a hard life, and it didn't help that within 20 seconds of the wheels spinning for the first time in almost two decades, that I ploughed it into the TV cabinet and broke the steering upright. The cabinet is just high enough for the nose to fit under, so the right steering upright took the entire force of the impact. Ooops... It stretched and almost tore it in half, so even with some JB weld, it's still on a funny angle. Oh well.

I went ahead and JB welded the other side as well - preventative strengthening for when I inevitably run it in the house again, and back into the TV cabinet.

jb weld ftw.jpg

Regarding the wheels and tyres - Traxxas axle carriers, axles, 4x 850 bearings, 4.8mm ball cups to suit M4 threaded rod, a hax saw and file are to be used to make this work.

bits that will make it better.jpg

I have also replaced the servo to steering knuckle link with 2mm ball ends and M2.5 rod. I drilled a hole in the steering knuckle so the fulcrum is around 2mm shorter, but using a servo-horn-hole that is also 2mm closer to the pivot means the total steering effort and angle remain unchanged. Actually, the "barely rolling" turning circle is so ridiculously tight I think I'll reduce this further anyway.

Here's what it looks like with the Traxxas axle carrier. I hope that's enough steering angle (I think it is).

is that enough steering angle.jpg

And here's the new steering link, nothing you haven't seen before.

Steering link.jpg

I also bought a random "Tamiya spare parts bag" from someone in the states for $10 shipped - lots of goodies, most importantly though, ceramic grease and AW grease.

Speaking of grease - I need more limited slip from the differential.

I tried quality automotive bearing grease - not sticky enough, and it was actually too thick (once pushed out of the way, it just stuck to the case wall and never got pumped through the gears - useless). I tried this incredibly sticky, polyurethane bushing grease but wasn't sure how it would handle constant loading in this instance. I tried 3mm washers between the bevel gear carrier and the outer gears - too tight, and the spacing was not in the correct place (gears would be meshing a little less). The AW grease certainly helps resist the open differential action, but the effect is so minor that I'm already destroying my old tyres - and they need to last another 2 weeks until the new items arrive.

So I have a plan - but let's take a step back...

Two nights ago I discovered Banzai - I had heard of it before, but hey I've only been looking into this for a few months now and it simply hadn't clicked that it was a Japanese based parts store.

So here's the Banzai shopping list

  • CVA dampers from a DT03
  • 5x8mm ball ends, because ball ends.
  • 5mm ball "collars", same reason.
  • The larger AW grease tube - so I can go excessive
  • 10mm differential shims - 0.2 - 0.3mm, 5 each
  • Both the 17 and 19T steel pinions - to have options.

The plan: -

  1. Use the tiniest amount of JB weld to block the two holes on either side of the differential case; prevent the grease from pumping out when its packed
  2. Use an additional shim (or two) on either side of the larger bevel gears, as well as the standard washer (hopefully preventing me from wearing away at the plastic)
  3. Pack the thing full of AW grease
  4. Hopefully have less openness to the differential

Yay, nay?

I've also been toying up with the idea of going brushless. There are so many on either side of this camp for vintage runners, and both sides have valid arguments.

Right now though, I'm running the 19T pinion with the Sports Tuned and 85mm diameter tyres (original Pro-Line's, no less). The 19T is perfectly fine in this instance for several reasons (which refute the reasons given by some on other forums who have said to never use the 19T in a DT01).

  • The reduction ratio, or roll-out, of a Mad Bull on 115mm diameter tyres requires a 15T pinion to be the same as using the 19T pinion and 85mm diameter tyres. Therefore, the motor in a stock Mad Bull (and therefore 17t pinion) has a far more difficult task, and it survives just fine - GregM absolutely nailed it.
  • I ran the 17T and paid close attention to the engine RPM at full speed, as well as how quickly it got there - then ran the 19T immediately after. Top speed and RPM were achieved maybe a quarter second later (honestly I could barely tell), but the car was going significantly faster. Acceleration was still traction limited from a standing start on these old tyres
  • I could touch the motor after 20 minutes of hard thrashing - and the motor is now braking into corners, rather than coasting for a while when I had no braking ability from the original MSC (thank you cheap ESC!).
  • Because fast
  • It doesn't need more acceleration from a standing start - with better tyres its just going to flip as it is

Now, point 5 is very important - regarding the new tyres that is. At the speeds it can go now (around 35-40ish km/h - yes I'm shocked by that as well), more grip is going to be fatal - I'm prepared for it do go down like this... Go fast, not brake enough, turn in, flip into a gutter, pick up 50 pieces of plastic and then go back inside and sulk...

It doesn't help that the suspension geometry is about as bad a sit gets - what on earth were they thinking?

wtf were they thinking.jpg

And even at these speeds, I've managed to snap (an already previously snapped and glued) damper end, which I repaired and then sticky taped for added strength ( lol...). I swapped the repaired bit to the rear, since it will receive less shear forces when I crash again.

Broken rear suspension.jpg

Which of course I did, stressing the exact same point on what used to be an as-good-as- new damper end (I'm not that bad, honestly, I'm just driving in the most inappropriate place possible)

already stressing the suspension.jpg

You might also note that I'm using the inside mounting location instead of the outside one. This is mostly to reduce the toe in, and I couldn't believe how much less under steer resulted from this. Not to mention that I started to wear out the outside of the tyre! With metal turn buckles I should be able to adjust the toe and prevent the excessive tyre wear. Not much I can do about the camber at this point, but since the new front tyres I've ordered are significantly wider, having a little too much camber to reduce the grip a little is probably a good thing.

But I digress.

Back to the brushless discussion - from what I gather, its down to three things: -

  1. Temperatures
  2. Gearbox longevity
  3. Drive-ability

Nothing else really matters. You need to be able to achieve the desired speed within your thermal and gearbox limitations. To that end, here's what I feel would be a reasonable setup, which is also considering the extremely cheapness of the components.

  1. Purchase the very cheap Leopard 3300kv Brushless combo - who can go past $50USD? That is also the absolute limit of my budget anyway.
  2. Never run larger than 90mm diameter tyres
  3. 17t Steel pinion for offroad, reserving the 19t for on-road, constant high speed use only. The 19t will also reduce the acceleration slightly, and since brushless motors have a lot more torque, this is probably a good thing.

This should ensure temperatures remain "touchable" for the most part, and the gearbox should have a relatively easy time driving the smaller diameter wheels compared with a Mad Bull.

I think that's about it. I hope I've posted this in the right place...

Any thoughts or suggestions are more than welcome, indeed they're invited. Keep in mind however, that this buggy has more sentimental value in the sense that I want this specific buggy to work to its maximum potential - so I'm one of those "Much rather keep something going and make it better" types. Though I have seen on Banzai that you can pick-up DT03's for $55 bucks - ouch.

Final thought - I'm glad I found this forum. Many of the ideas that made this rebuild far more enjoyable were found here, from the steering improvements (and potentially modifying the front end to handle double wishbone), through to simple things like using AW grease in the diff, have helped make this a lot of fun. Cheers for that.

Front end bottom up.jpg

post-45414-0-81561200-1452812527_thumb.j

post-45414-0-00138500-1452814304_thumb.j

post-45414-0-90289900-1452815215_thumb.j

post-45414-0-61111200-1452815320_thumb.j

post-45414-0-62589600-1452815321_thumb.j

post-45414-0-87748100-1452815726_thumb.j

post-45414-0-41112500-1452816164_thumb.j

post-45414-0-89185200-1452816180_thumb.j

post-45414-0-83089000-1452816225_thumb.j

  • Like 4

Share this post


Link to post
Share on other sites

More photos of the traxxis front end job please. Part numbers would be great.

Tamiya putty in the diff works well rather than trying to seal it and use oil.

DT-03 is a must. You need a buggy so your son can run the other one

Share this post


Link to post
Share on other sites

More photos of the traxxis front end job please. Part numbers would be great.

Tamiya putty in the diff works well rather than trying to seal it and use oil.

DT-03 is a must. You need a buggy so your son can run the other one

Here's the list that you want to use, not the stupid mistake purchases that I ended up with (I'll explain later).

Pair of Traxxas axle hubs (they call them "Steering blocks") part #3636

Pair of Traxxas axles #3637

Pair of 12mm hex wheel hubs (w/pins) #3654

4x 850 bearings

250mm length of M3 threaded rod (or "M3 all thread") (madly cheap on ebay)

4x 4.8mm ball rod ends with M3 thread (all standard Tamiya 5mm rod ends are actually 4.8mm ball size, and 90% are M3 threaded)

Hax saw the extended collars and then file them flat like this image. One hub is still as new so you can see what I mean, the other fits snuggly, but freely, in the standard C carrier on the standard lower suspension arm

post-45414-0-34269900-1452853830_thumb.j

I regret purchasing these "heavy duty" Traxxas turn buckles, I got them when I dropped into a random hobby store on the way back from a customer site. I thought they were 5mm ball connectors, but they are 6.8mm (I was tired...). And the M4 thread is not used by basically anything with a 4.8/5mm ball connector, so that screwed me over a bit...

This forced my hand to try and find M4, long neck ball ends, which once they arrived, it turns out I couldn't really find - these aren't long enough, and they're for M3.5 thread. So I'm hacking these up to work with M4, as there is enough meat there to do so.

So I've ended up purchasing some M4 all thread and I'm waiting on that now. I'll then cut this to length, use the Traxxas heavy duty ball connectors (collars actually) at the axle hub, fasten with some M3 bolts, spring washers and normal washers so they stay super secure, and the 5mm ball rod ends that I'm hacking up will be used at the steering knuckle (no choice).

Regarding differential putty - I spent far too long the other night looking into this, and honestly, it just seems that no one has a clue how it actually works (or at the very least, how differentials are meant to work... Even the apparent "pro racers").

I don't want to lock the diff - that would be absolutely detrimental to the cars handling - it would understeer even more than it already does (though, the new tyres will likely reverse that, and I'm probably going to spend more time flipping over than turning - but we'll see). I want to double, or triple, the resistance to being "open", and nothing more. If you have any experience with diff putty, while trying to achieve a similar effect, please let me know how you went about doing so, that would be truly helpful.

I also went and ran this out on the street where I could really nail it and hold for a prolonged period to ensure it was really up to absolute max speed, and I think my 35-40km/h estimation was a little generous. 32-34km/h would be more accurate, but it was difficult to time so, I could still be off... I'll update when more bits arrive. Cheers for now.

Share this post


Link to post
Share on other sites

I like what I see. Maybe that is because I have a fondness for DT-01 builds, especially those that go beyond the stock design like yours. Keep on with the good work!

Share this post


Link to post
Share on other sites

That is great info, I will look up the parts.

The first time I used putty I used 1 cm on each planet wheel and it gave a smiler effect to what you describe after a couple of hard run. I like mine a lot tighter as I run on sand and wet grass and use an on/off throttle driving method.

Share this post


Link to post
Share on other sites

I like what I see. Maybe that is because I have a fondness for DT-01 builds, especially those that go beyond the stock design like yours. Keep on with the good work!

Thanks Greg. I certainly referenced your thread many times, as well as many other posts you've made.

Like I mentioned above, the roll-out of you're Mad Bull with a 15t pinion and 115mm diameter wheels, is the same (to 2 decimal places, before any ballooning) as a 19t pinion and standard buggy wheels.

So you've really nailed it accommodating for the larger wheels. In fact, your staying within the original design specification to some degree. And considering the DT01 is about as light as 1/10th buggy gets, it doesn't surprise me to hear of the dozen or so DT01 bashers running 4000kv+ brushless without issue on standard buggy size wheels.

I'm also seriously considering the DT03 lower arms + C hubs + threaded rod, multi-link front suspension mod, which would eliminate the insane camber increase with compression, but I'm concerned that the additional fixed points would load up the plastic when I crash it again, and destroy bits that are far more difficult to repair... Any thoughts on this?

Finally, nobbi, did you apply the diff putty in a DT01? Did you also use grease in the diff with the putty? And is it a fairly permanent effect, or have you had to re apply?

...

Skipping forward a few hours since I wrote the above, and after I took it for a hard run on some less-that-grippy AstroTurf, I really need more differential resistance, because it's appalling, even with AW grease in there. If I get a chance I'll pull it apart later and inspect.

But I do have an idea on how to make the diff tighter, somewhat permanently and without damaging anything (I think). Once the shims arrive I'll write a new reply, that is, if my idea actually works of course.

Cheers.

Share this post


Link to post
Share on other sites

I used HPI heavy duty grease in the differential.

http://www.modelsport.co.uk/hpi-heavy-duty-grease-10g-/rc-car-products/25879

I've been very pleased with it. Before using this I had a problem with the diff spinning up on my brushless WT01, basically the truck totally lost drive, I thought the grub screw had come undone on the pinion or that I'd lost a pin from a hex hub, but lo and behold I discovered it was the diff and purely by accident, after checking everything and I couldn't see any signs of slippage I decided to pack the diff with thick grease while I was there as I was planning to do it anyway and it totally cured the problem!

Cheers

Nito

Share this post


Link to post
Share on other sites

The putty effect lasts longer than grease but not forever if you use little. If you use a lot (tight pack) then it works in to a very nice effect over time but it takes a good few runs to get there. Putty is less effected by heat so it does not go loose after the second pack of the day. I have 2 DT-01's with putty in the diff.

Shimming works well in automotive diffs but I suspect in cheap plastic ones the will ware or spread quickly

Share this post


Link to post
Share on other sites

I used HPI heavy duty grease in the differential.

http://www.modelsport.co.uk/hpi-heavy-duty-grease-10g-/rc-car-products/25879

...

Cheers

Nito

Hi Nito - is that grease sticky? The problem with these DT01 diffs is that they don't seal well, and there is enough space around the bevel gears that once a tiny bit has pumped out, the rest seemingly avoids the gears, clinging to the case walls instead... It was poo, and I was using really, really thick, no flow grease... It just wasn't sticky enough. Stickiness almost seems more important than viscosity, but I'm sure that's just because of what I've tried.

If that stuff is sticky AND thick, it might do the trick though, cheers.

The putty effect lasts longer than grease but not forever if you use little. If you use a lot (tight pack) then it works in to a very nice effect over time but it takes a good few runs to get there. Putty is less effected by heat so it does not go loose after the second pack of the day. I have 2 DT-01's with putty in the diff.

Shimming works well in automotive diffs but I suspect in cheap plastic ones the will ware or spread quickly

Ah, but my plan is genius :P

These shims have more surface area than the standard washers, so they should protect the plastic.

Instead of the three black 2.5mm screws holding the diff casing together, I'm using 3mm screws instead (the gold coloured ones normally holding the MSC down are the perfect length without washers, so I may need to go longer).

Then, using proper strength 3mm spring washers, a tiny bit of very low strength lock tight (just to be sure), I should be able to keep it fairly tight, even if a little wear occurs. Any "slack" will be taken up by the spring washers holding the entire diff tight. It will only hold about 0.2mm of play at the right compression, but that should be all I need. I can't imagine wearing out 0.2mm of metal from the diff, since part of the goal is to avoid plastic to metal surfaces slipping, but rather, metal to metal surfaces only. That's the hope, anyway.

I may even try to bond a shim to the plastic to try and ensure this. We will see how it goes, it could be a complete fail...

Which diff putty would you recommend though? I still might try that first, and see what I prefer if "The Plan" works out.

Cheers mate.

Share this post


Link to post
Share on other sites

Very sticky/tacky and thick. I'm pretty sure it was designed for boxes and recommended for use in the Savage flux from memory. It doesn't fling or leak out.

For the cost of i,t worth a try? I've had no issues since using it. I've not tried putty so can't comment on that.

Cheers

Nito

Share this post


Link to post
Share on other sites

I have only used the Tamiya putty.

I like your plan. Put it in to action and see. The diff used in most other modern models is not far off the same basic design so if works for one it should work for all.

Share this post


Link to post
Share on other sites

Loctite into plastic does nothing aside from potentially harming the plastic. It is intended for use with metal screws and nuts/threads.

I guess the plastic material of the diff case might be difficult to glue, as it may repel glue.

Share this post


Link to post
Share on other sites

Spring washer sounds an interesting idea! You'd probably only need one on one side, I like the sound of that!

Share this post


Link to post
Share on other sites

It could be completely balls though, so, we'll see when the shims arrive in about 2 weeks.

Share this post


Link to post
Share on other sites

Ok so, I realised that because of the steep angle of the steering hub arm, the previously thought-to-be-too-short Traxxas turn buckles actually fit, so I made it happen.

And wow, what a difference.

Excuse the image linking - this forum seems to have issues with, well, images... Very odd, I've never had these issues before with externally hosted pictures.

Anyway, click the link and you'll get them.

Take axle carrier #3636, remove collar extensions, then take a 3mm drill bit and by hand carefully open up the pivot bolt receiver. One pass in both directions is enough, you do not want slop here.

th_20160117_084048_zps1xkprewm.jpg

Flatten it to size - try and keep it as "square" or "true" as possible

I used some 2500 to polish this surface since it needs to be free of grooves or scaring in order to reject dirt from trapping itself in there, while operating smoothly.

th_20160117_083207_zps2vxhcwwy.jpg

This part differs from what everyone else should do - everyone else should either use 3MM threaded rod, or get some longer turn buckles from a Tamiya kit. However, for reference of what NOT to get, these are Traxxas #3643 - 82mm centre to centre in default position. With the standard "Traxxas" rod ends, this is fine. But with shorter rod ends found anywhere else, you will worry about how many threads are engaged - like I am, constantly....

But the rest is fairly self explanatory - I may or may not trim those bolts down - they look kinda cool like this for some reason - even though they look a little messy.

th_20160117_094235_zps6tjlrabt.jpg

All tightened down and look - no toe in, other than what I dial in to get the handling right.

Yes, it looks stupid with the hex hubs and stock wheels; that exaggerated track width does wonders for the handling however.

th_20160117_143551_zpsy2ikod2i.jpg

Share this post


Link to post
Share on other sites

New wheels and tyres arrived today. Yes, I understand these are cheap from-the-middle-of-nowhere Chinese rubbish, but come on - they are so out of balance, and they are not square. I can't show this to you in images, but I'm quite disappointed. I may have to take the old tyres off the beaten-to-death wheels and mount the new tyres on those instead. I was never even into the dish wheel look, it was just the road tyres that I wanted from this set and they happened to come with white dish wheels. However, I was quite looking forward to being able to at least run 4 wheels of the same design for once... It also doesn't seem like the axle holes for the fronts were drilled central, not to mention that even after working this out (by tightening the wheels on the thread only for a test), I also had to bore the axle holes to 5mm to fit. I don't have a drill press, so I couldn't correct the off centre hole. This is pretty unfortunate, since I have no idea how this will effect the cars handling, but I suspect it will vibrate it to pieces...

Adding insult to injury, the "40mm wide rear tyres" are only around 37mm wide, and I'm being generous. That's over 8% less contact area and a tonne of grip lost. They weren't even the cheapest wheels on ebay, I thought the "second cheapest wine" rule might apply here - apparently not...

th_20160118_140030_zpsvtllul13.jpg

But otherwise, they feel nice and grippy, so hopefully the thing will actually perform better now. Once I glue them on, then maybe I can use double sided tape to balance them a little and make them usable - I hope so!

The fronts are about 31mm wide - I hope this isn't too much front end grip considering my expectations for rear grip are now far lower...

th_20160118_132554_zpse3fdqlho.jpg

I wish I had longer springs at the rear - I don't like the poofterish front-end-in-the-air-fully-sick-looks-like-I'm-always-accelerating stance that all the try-hard idiots are into these days, so hopefully the CVA dampers are slightly longer (I think they might be) so I can also avoid this look in scale cars as well.

th_20160118_124957_zpsepp6i1oe.jpg

I've also worked out that you can reduce the bump steer with the essentially stock suspension. By stock I mean no multi-link or major geometry modifications (like modifying the DT01 to take DT03 lower arms, C carriers, and using threaded rod on top to get the second link).

The key ingredient is having the ability to increase the height of the ball joint with respect to the steering block/axle carrier.

I just used 3 washers, like so...

th_Increase%20height%20of%20connecting%2

I limited this to 3 washers so that there was still around 3mm of movement before the turnbuckle would foul the chassis at maximum suspension travel (allows for a little engineering factor). You could probably get away with 5 washers in a newer, better condition front end - but mines beat to crap and floppy, and bent, and who knows what else.... But 3 still made a surprising difference!

I wouldn't try and do this with the standard turnbuckles though (by say, punching the stock brass ball connectors from the stock steering block/axle carrier, and replacing with ball collars and spacing them), because it increases your static toe-in.

It required two paragraphs to explain exactly what the geometric consequences are of what I've done, but hopefully this drawing makes it easier. I've heavily exaggerated the angles and arc lengths here, but the principle effect is accurate.

th_Geometry_zpsqpeuxyna.jpg

From the above, you can see that the horizontal distance travelled by the end of the turnbuckle is lessoned throughout the suspensions movement, and therefore so is the toe-in induced by this movement.

The result?

th_Reduced%20bump%20steer_zps2aajcoaw.jp

That's pretty substantial if you ask me - please also note that I have not shortened the turnbuckle length to compensate for the increase in static toe-in caused by the above modification, and yet the angle difference is still that massive. It will be even greater again when I slightly adjust this to have almost zero static toe-in (depending on how it handles).

I haven't driven it yet as need to get to the hardware store to purchase some glue for the tyres (they arrived earlier than expected). Hopefully the handling improvement is at least noticeable - I think it might be.

This is a crap load of fun. Modifying this thing is way more enjoyable than bashing it around as a kid. So is driving it for that matter... Why was this originally a kids toy again?

Share this post


Link to post
Share on other sites

Without glue, I didn't want to bash with the new rear tyres, so I went for a quick spin with just the new fronts, with old tyres on the rear.

Take 1.

Barrel roll not 2 metres after giving it power.

Take 2.

Barrel roll returning from take one immediately after my nephew turned it over for me...

Hmmmm..

Take 3.

Doughnuts, lots of doughnuts, followed by another barrel roll.

After I stopped cocking about, it was a blast having to actually try and steer more precisely, brake in a straight line, turn in gradually...

But now I need to work out how to fix the upright (maybe make one from aluminium? Any ideas?), and lower the centre of gravity... I'm sure with a lower C.G, the grip and centripetal force I'm wasting flipping over, could be turned into useful cornering speed and stability. Any ideas?

Share this post


Link to post
Share on other sites

Links no work for me :-( looks like Google wants to keep all you images to its self

Share this post


Link to post
Share on other sites

Same for me - and I'm really curious what you've done for further mods! :)

If you've got trouble linking your pictures, please try a different browser or a different host for pictures (e.g. Firefox and Photobucket). The forum has some quirks and issues with Internet Explorer and Opera (past versions before the merge with Chromium) when posting pictures.

Share this post


Link to post
Share on other sites

Think the "images" in Google are not images put page links. One drive does the same thing so linking is not possible.

Share this post


Link to post
Share on other sites

So I've shared the album and then created shared links to the appropriate photo within the album, and updated the above accordingly.

I think.....

You just have to put up with it opening in google photo's with the google banner at the top. I was trying to cheat earlier by linking directly to the images.

Share this post


Link to post
Share on other sites

Right, so here's what's going on. I glued the rims and tyres and went for a bash.

Awesome - just awesome. It seems the barrel rolling was produced because the back would slide due to having so much front grip (and therefore slides were induced at much higher speed), and combined with those old rear tyres (which aren't properly glued and would peel a little), it would dig into the surface, and since there was so much momentum this would end in a flip. Not so with both front and rear on-road tyres mounted - the balance was still a tiny bit tail happy, but this is because I was sent 37mm tyres instead of 40mm - I've complained and it looks like I'll be sent a new set since these are clearly the wrong items.

Which is a good thing because not 2 minutes into my first run with this thing at proper grip levels, I had a mental fart (combined with still having a little less rear grip than I should) and slid the back end into a gutter. Being cheap, hard plastic Chinese wheels, this cracked the rim.

Argh...

Hopefully my Banzai order arrives before I destroy this thing, CVA dampers sound like fun...

Question - does anyone have any ideas for making a new front suspension upright? I have some ideas and all of which are massive hack jobs. But the cheapest I can get the F parts bag is $27 delivered and that just seems like a complete rip-off when I only want a single bit of plastic that I'll likely destroy the first time I run with it.

One idea I was toying with was possibly chopping about half of the upright off, bolt through (and sikaflex) what remains to some 2mm aluminium sheet on either side, cut to the appropriate size, sandwiching the remaining upright.

I don't know. I don't want to spend money on a part that is no better than a standard part that is clearly not up to task.

What I do know however, is that the right side upright bolt is pointing off inappropriately like a boner, which is ruining the handling and all of my hard work trying to remove bump steer and static toe.

So if anyone has any thoughts or suggestions on somehow fixing the front upright, please let me know.

Share this post


Link to post
Share on other sites

I have wondered about the front mount. My fear is a stronger one will just pass the shock on to a weak bit of the tub where it attaches

Share this post


Link to post
Share on other sites

I have wondered about the front mount. My fear is a stronger one will just pass the shock on to a weak bit of the tub where it attaches

Been thinking the same thing.

...

So my Banzai order just arrived, and I'm happy and *******ed off at the same time. The diff washer in the DT01 manual is listed as 9mm, perfectly normal. One would then expect that 10mm washer shims should be slightly oversize and definitely work (oversize as in 10mm vs 9mm), since there is ample room around the OD of the standard washer for probably another 2mm. Surely I couldn't possibly be incorrect - as an engineer, I deal with international standards all the time, and listing the ID or the thread size a washer suits is the international standard. Tamiya would surely be smart enough to follow this nomenclature.

WRONG.

Tamiya, in all of their wisdom, uses the OD for shims, and the ID for washers. Thanks - you pricks. Where will I get appropriately sized shims then?

The good news is that the CVA dampers arrived. Using the ball collars and some M3 bolts, I bodged up some rear top mounts that work a treat... (yes I flipped it with the top off already. Argh..).

th_20160121_181737_zpsrrvcyhzr.jpg

While straightening the damper action a little...

th_20160121_181909_zpsxlab6v0r.jpg

I also found that acetone and cheap Chinese rims are not friends..

th_lol%20-%20Chinese%20wheels%20dont%20l

lol

This was a pain to clean off the tyre, but eventually we have a Frankenstein wheel combo, so we're back to having awesome grip again (well, sort of - I need to set up the dampers properly first).

Speaking of which; the oil filled dampers seem to make a decent difference, but not as much as I expected. And thinking about it, there's a good reason for this - I used that super sticky polyurethane bushing grease in the friction dampers, which would have made their action somewhere between the oil filled and standard. But nonetheless, this is a good improvement and the car is more stable. Brilliant. I just need to figure out how much pre-compression will accomplish the required balance, maximise grip, and hopefully reduce tyre wear. Poor balance usually = reduced tyre contact = worse grip and more wear.

There is one issue that I seem to be having though. When the rear dampers are fully extended, they somewhat "bind" a little. In fact, when the car has been sitting for a period of time, its actually quite stiff - what could cause this? I lubricated the O-rings (I over did it if anything, so that can't be it). It's not an air bubble in the dampers, I double checked that. It certainly seems to have a lot to do with the articulating angle of the rear end - like it goes past this certain point where the force required to compress the dampers is beyond some critical level (seeing as the force applied in the vertical would be a factor of the arc tangent of something multiplied by something pi squared, erm.... - Yeah university was a long time ago - but basically the vertical compression of the suspension translates to a rotating action around the lower pivot. The component of that force in the axial direction of the dampers is certainly very small when fully extended. Maybe the dampers being "slightly longer" is hurting performance - I may need to use the "shorter" damper end. ******!

Any other ideas?

What I'd like (and what I really think we need) is to come up with a universal way of easily improving the rear suspension mounting points. GregM, you posted a video of this guy who went really crazy with a Mad Bull and had the rear springs only 30 degrees from vertical, going over a bunch of jumps and such. I couldn't get a frame of what he'd done from the video...

So there's our mission - come up with some de facto standard DT01 rear suspension improvement mod... Something easy enough for anyone with a set of screwdrivers to accomplish.

Share this post


Link to post
Share on other sites

Great job so far!

As you found out by yourself, acetone is destructive against some types of plastic, e.g. polystyrene (which is the material the Fighter Buggy RX bodyshell is made from, too).

For optimizing the suspension, I'd go for very thin damper oil and soft (but long) springs in the rear shocks. It doesn't hurt that the car will be sagging a bit when standing still, as this is rather a desired feature. Once you apply throttle, the DT-01 will get itself high up again anyway. Another thing that came to my mind when looking at your photos, you can go for ball mounts instead of straight screws or step screws. This will help with the weird 3-dimensional angles of how the dampers are mounted. I do not trust regular ball mounts for dampers, since the dampers may disengage on impacts or jumps. I'd rather use ball nuts with long M3 screws, or even better ball collars with long self tapping screws:

http://www.tamiyaclub.com/forum/index.php?showtopic=67074

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×
×
  • Create New...