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Juhunio

Juhunio's Super Duper Astute. Er.

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A small but satisfying step today, installing the servo. I love these Savox 1251MG servos, and it will be nice and visible mounted on the SA chassis, built out with the obligatory HT servo saver and some  unnecessary but pretty servo bling!

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Annoyingly I've run out of low-friction adjusters so I'm waiting for some to crawl here from Hong Kong. So the kit adjusters will have to do for the steering rod for now, built around an 18mm turnbuckle 

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The servo lead is too short to reach the spot shown in the manual to mount the receiver, so it and the ESC will have to swap sides

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Sooooo, dampers.....

Early last year, before the VQS Hi Cap set came out, I went about cobbling myself together a set of hi caps for the super astute

I started with a Top Force Hi Cap set, then sold off one pair of long cylinders, springs and rods and bought a set of short front cylinders, springs and rods using part codes from the Egress manual

I also bought a set of long Egress rods, which turned out to be identical to the longer rods in the TF set, so sold the TF set too 🙄

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Just not sure now on how to build them; the TF hi cap instructions uses a combination of o-rings and spacers inside and outside the cylinders, the egress manual uses no spacers or o-rings, and I’ve seen the first bit of the VQS hi cap instructions which use a different combination of spacer and o-ring on the fronts!

🧐

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I decided to do a 'dry' build of the SA kit dampers and Hi Caps to see where the differences might be and what spacers might be required

Starting with no-spacers or extra o-rings.....

The rears ended up pretty much identical, at a gnats hair difference around the 83/84mm mark eye to eye. The kit piston rod was 1.5mm shorter than the Egress rear rod, but the final difference is less than 1mm although fully compressed (without oil) the difference is more significant; kit dampers are 63mm, hi-caps 58mm

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Bit more in it with the fronts. The kit front rod is 4mm shorter than the Egress front rod, and the dampers end up 2.5mm longer; the kit dampers are 61mm eye-to-eye, the hi-caps 63.5mm. But fully compressed they're near identical at 49.5/49mm

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I think that means in order to match the ride height and stroke length of the SA kit set up, it's best to build the Hi Caps without spacers and use the spring tensioners to balance the F/R ride height 

The springs will also have an effect on the compression, the kit springs have more coils than the hi-caps. But I can’t see a hi cap spring set anywhere, did such a thing ever exist? 

 

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Built the hi-caps this morning, not a huge amount to report other than the red oil seals don't seem to be a very good fit

It's (I think) pretty much impossible to rest the seal on top of the full damper cylinder and then screw the cap on over it without dislodging it. It's just too big

The only way I could get it to work was to drop the seal onto the oil in order to push out any excess, then remove the seal and push it down inside the cylinder cap before screwing the cap on

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That seemed to do the trick, all the seals went on ok after a few attempts and the action on each damper was smooth, quick and quiet which indicates no trapped air. 

But it did seem a bit of a nonsense for what are quite an expensive hop up. Have I missed a trick here, or are those seals really not the best of jobs?

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With that palaver worked out, it was time to attach the dampers. The SA uses a one-piece damper mount (19804987) on all four corners, whereas the hi-caps use a combination of balls, bushings and spacers.

A quick check of the Top Force manual shows it uses the same damper mounts as the SA, and as the hi caps are a direct hop up for the TF it follows that the mounting parts for the hi-caps directly replace the damper mount, so the same would apply on the SA

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The rears are a very straightforward fit, with the mounting parts at the top and a ball connector nut at the bottom. I found that the 20mm screw was a little bit too long and protruded through the lock nut, so I added a 1.5mm spacer between the damper stay and the lock nut

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The fronts were a little more complicated, as they're mounted inside the wishbone and at first I couldn't get the Super Astute ball connector to fit into the hi cap damper end. I messed about with 5x4mm tubes and trying to screw a ball connector nut inside the wishbone, then had another last go at getting the ball connectors to fit into the damper end and they went straight in no bother :blink:

Same addition of a 1.5mm spacer between the damper stay and the lock nut, and I used some black lock nuts in the end too

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8 hours ago, Juhunio said:

Built the hi-caps this morning, not a huge amount to report other than the red oil seals don't seem to be a very good fit

It's (I think) pretty much impossible to rest the seal on top of the full damper cylinder and then screw the cap on over it without dislodging it. It's just too big

The only way I could get it to work was to drop the seal onto the oil in order to push out any excess, then remove the seal and push it down inside the cylinder cap before screwing the cap on

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That seemed to do the trick, all the seals went on ok after a few attempts and the action on each damper was smooth, quick and quiet which indicates no trapped air. 

But it did seem a bit of a nonsense for what are quite an expensive hop up. Have I missed a trick here, or are those seals really not the best of jobs?

Hi Juhunio, in my eyes you have missed nothing here,

and done the only correct way to assemble them with the existing parts. Tamiya did unfortunately not rerelease the original bladders, which were top stuff, and reused some CVA bladders, which are not fitting very well. After 2 or 3 misattempts I also found the only way to get the sitting correct is as you did it, lay them in the Topcap first. The Rere Hicaps are also not "vented in the topcap" as the original ones, so they have a little rebound. Guess, that´s why Tamiya recommends filling them with the piston rodpushed in some mm´s (see the manual). As far as I know, this is the first manual I saw, where TAmiya did not build the dampers with fully extended piston rod.

Good thing is: You could replace the bladder with an O-ring and build "aeration" buggy dampers for testing, as on the Dyna Storm or on newer buggies, where nearly no bladders are used. 

Or you can drill the topcap in the middle as on the original Hicaps for less rebound effect.

But I really miss the Original Hicap quality a bit. Rod guide is o.k. on the new ones with a screwed design, easier to assmble as the original c-clip design. But An original Hicap was so nice: Fill the oil, bladder on, Screw topcap on, very smooth operation with zero rebound (or almost. old orange O-rings were also not really low friction ones).

But your project is coming along very nicely!!;)

 

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12 hours ago, ruebiracer said:

Guess, that´s why Tamiya recommends filling them with the piston rodpushed in some mm´s (see the manual). As far as I know, this is the first manual I saw, where TAmiya did not build the dampers with fully extended piston rod.

Thanks Matthias, I will admit I had missed that detail in the Hi Cap build instructions and built mine with the piston fully extended. I'll rebuild them today as per the manual :)

I have two more questions that maybe you can help me with?

1. Rebound; I tend to build my (CVA / Hi Cap) shocks so that once the oil is filled and the bladder is in place and the cap is on, if I push the piston fully in it will then 'rebound' quickly and fully so the full piston rod is outside the cylinder. Is that....wrong? Should I be looking for a different action?

2. When I mounted the Hi Caps to the chassis and put the wheels on, the (heavier) rear of the chassis will hit the ground before the the dampers were fully compressed. But the 'lighter' front would not, the damper would fully compress and the chassis is still 10mm or so above the ground. Is that....bad?

Thanks in advance for your (and anyone else's) help and advice!

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44 minutes ago, Juhunio said:

Thanks Matthias, I will admit I had missed that detail in the Hi Cap build instructions and built mine with the piston fully extended. I'll rebuild them today as per the manual :)

I have two more questions that maybe you can help me with?

1. Rebound; I tend to build my (CVA / Hi Cap) shocks so that once the oil is filled and the bladder is in place and the cap is on, if I push the piston fully in it will then 'rebound' quickly and fully so the full piston rod is outside the cylinder. Is that....wrong? Should I be looking for a different action?

2. When I mounted the Hi Caps to the chassis and put the wheels on, the (heavier) rear of the chassis will hit the ground before the the dampers were fully compressed. But the 'lighter' front would not, the damper would fully compress and the chassis is still 10mm or so above the ground. Is that....bad?

Thanks in advance for your (and anyone else's) help and advice!

Hi Juhunio,

I´ll give you my personal experience / thoughts about damper building here, so if anyone will disagree, it´s o.k. for me.

1. There is no real "wrong" here. In RC damper business, everyone builds it different, to their personal likings. At first, I find "rebound" a bad term, as in reality, it is a compression force, that adds to the force of the spring. So it is most of the times on a real car. As modern shocks are mainly gas pressurized by low pressure or high pressure (monotubes), the gas forces on real shocks can also vary from low to high values. 

Tamiya recommended from the beginning at shocks with "bladder" the physically "correct" position, which is fully extended during closure process. (bladder on, screwing the topcap). So if you screw on the topcap, the air above the bladder will most of the times get a little more than ambient pressure, as the air cannot get fully out the topcap. (Unless you drilled the topcap for ventilation, or you have a shock with a ventilated cap, e.g. Vintage Hicaps). So you get a little "gas force" like on a real shock, that pressurizes the oil. This is a good situation to avoid cavitation. But as we are on RC and not 1:1, there will not be real cavitation in a model shock. 

But this way you´ll get a very consistent shock action over many runs, even with a little oil loss.

-oh ****, think I lost myself in my favorite philosophy -:lol:

To not bore anyone here: In short words, build it as you like! But for sure you can try different positions of the piston rod as on the Re-re Hicaps. In onroad, most of the racers build nowadays zero to minimal rebound. Offroad I´m not in the real race business since 1993, so I don´t really know the majority. But as most of the modern offroad dampers are aeration type ones, so they mix air and oil, so they will be more of zero rebound or even negative rebound (shock wants to suck in the piston rod from fully extended position. Compared to the springs used, these forces are not really high, but can have a bigger influence on the feel of the car during cornering, braking etc..

2. easier answer: Nowadays with very high jumps it´s better to let the chassis contact the ground and not let the shock limit the travel and keep the chassis from ground contact: This would lead to very high forces after landing big jumps going in the shock towers, so they will be prone to breakage. Every bigger race buggy like the 1:8 nitro ones have it this way since years. But depending on the us of your Super astute you will not get problems on the front, I guess.;)

Sorry for my excursion,

hope you get some useful info out of my words...

:ph34r:

Kind regards,

Matthias

 

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Thanks @ruebiracer, that all makes great sense :)

I've rebuilt the hi-caps with the pistons pushed in a bit as per the instructions, and when built they naturally 'rebound' (if that is even the right word!) the piston back out to its full extension, so I'm going to go with that as 'correct' (like you say, if there even is such a concept :))

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Did a first cut of the shell today for a test fitting. I must say it's not the easiest to get on and off, it needs a bit of.....persuasion

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It is also VERY tight at the back, to the point that the rear of the shell rubs against the Hi-Caps, there is no clearance at all

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I tried changing the ball nut for a 'short' ball nut, which did buy an extra mm or two....

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But I still wouldn't say it fits. If I compress the rear suspension the contact between the spring and shell is audible :(

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A few tests of the suspension has already scratched the shell, which thankfully still has the protective film on it :unsure:

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Is this a known Super Astute 'thing', the body shell rubbing against the springs? Conscious I haven't put the undercowl and velcro attachment on yet, but can't imagine that is going to increase the clearance :wacko:

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Hi Juhunio,

I think this problem was also discussed in another thread here, maybe the Super Astute thread. Not 100% sure, where I read it.

What would interest me, if it was already on the Original Edition, or only at the ReRe one...

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22 hours ago, ruebiracer said:

Hi Juhunio,

I think this problem was also discussed in another thread here, maybe the Super Astute thread. Not 100% sure, where I read it.

What would interest me, if it was already on the Original Edition, or only at the ReRe one...

I'll go thread-digging and see what I can find, it definitely seems like too-tight a fit :wacko:

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I wanted to install the receiver on the side specified by the manual, next to the recommended position for the antenna post which would mean that the antenna tube would thread through the pre-drilled hole in the shell

But the lead on the Savox servo is way too short for that, so I ordered a servo extension lead which turned up today:

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This meant the receiver could sit next to the antenna post, and the Quicrun ESC cable could thread around the front of the battery tray with the switch installed on the side of the tray

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Tidy!

That meant I could stick a battery in and give it a quick hallway test. YAYYY! Which threw up a problem. BOOOOO!

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It kicked massively to the left. Basically the right wheel was spinning hard and taking the left wheel along for the ride, rather than both spinning together

Clearly something wrong with the diff 

Thankfully that little hatch in the base of the gearbox makes diff access a cinch. I took the diff case out and re-inserted the outdrives to see how it all moved when removed from the chassis. One side span freely, but the other side was completely locked solid, no way it was moving at all. Hmmm. Further investigation needed 

Once I got the casing apart I could see I actually had two problems, both shown in this pic:

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Firstly, on the left you can see that all the 500k Diff Oil (pretty sticky stuff) had leaked out. No big deal, replace it with heavier duty even stickier stuff

The bigger problem is the collection of gears on the right. I've mounted them all the same way up; they all fit, and the diff went together easily, so no problem right?

Wrong.

The instructions actually clearly state that the four gears have to be mounted alternatively turned-about. I'd completely missed it:

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So I rebuilt the diff with the gears the right way up, and 1,000k oil. I've cooked with molasses less sticky than this stuff :lol:

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Here's the fully assembled thing; the gears actually have slightly different markings on the spindles which show that they are mounted alternately. Handy!

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And hey presto, it all works and spins freely! It's all back together again and the hallway test went beautifully :D

Need to spend a bit of time tomorrow correcting the toe and camber and then that will be the chassis pretty much done :)

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I did an Astute shell for someone on here. Was somewhat horrified at the trauma of getting it on to the chassis. I had one of these BITD and I can't remember it being such a hassle to get the shell on and off....

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Flip your top damper mount screws on the rear dampers so the nut is protruding at the back and not the front.  This helps with body fitment .  You do get used to how to easiest fit the body with practice.  You settle the rear first over the under tray then drag the nose into place.  If you move your lower damper mounts to the outer position you improve the body clearance at the rear.  Move the front dampers to the outer position too though.  Your c.o.g will be lower and it maximises up stroke in this position.  Also less angle on your driveshafts.  Give these a try, I think you'll get a little improvement.

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On 4/16/2021 at 4:49 PM, Howards said:

I did an Astute shell for someone on here. Was somewhat horrified at the trauma of getting it on to the chassis. I had one of these BITD and I can't remember it being such a hassle to get the shell on and off....

It is weirdly tight, the issue seems to be getting the rear 'cowling' over the rear subsection. I haven't painted or fitted the undercowl yet, and when I do I'm going to try just using the velcro to attach the shell and do away with the rear body mounts, see if that makes it any easier!

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On 4/17/2021 at 1:26 AM, Thommo said:

Flip your top damper mount screws on the rear dampers so the nut is protruding at the back and not the front.  This helps with body fitment .  You do get used to how to easiest fit the body with practice.  You settle the rear first over the under tray then drag the nose into place.  

Thanks Thommo, that has helped a bit though it still seems very tight. I'll get used to it, but have ordered a Kamtec replica shell that I'll feel less guilty about being rougher with!

On 4/17/2021 at 1:26 AM, Thommo said:

If you move your lower damper mounts to the outer position you improve the body clearance at the rear.  Move the front dampers to the outer position too though.  Your c.o.g will be lower and it maximises up stroke in this position.  Also less angle on your driveshafts.  Give these a try, I think you'll get a little improvement.

That has definitely bought an extra couple of mm and created a wee bit of clearance at the back. As above I haven't painted or attached the undercowl / velcro attachments yet which might (I guess?) pull that rear section of the shell in a tiny bit too 

It also doesn't seem to have affected the ride height a whole heap, the front end still doesn't bottom out before the shocks :lol:

Thanks for your help :)

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I just had a closer look at my re-re and their is a gap when the car is at rest, suspension arms horizontal.  It's literally a paper thin gap so folded the paper in half and it still slips into the gap without resistance.  

 

 

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18 hours ago, Room335 said:

RE: the thread title, definitely super. Great work as usual @Juhunio !

Cheers!

Actually, after getting hold of the CF chassis upgrade set, I've changed the name of the thread! It's becoming a bit of an uber-Astute :lol:

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I like to have a spare body shell for buggies, one for running and one for presentation, but SA shells are impossible to find

So I thought I'd try 3rd Party Repro, and got this Kamtec effort which arrived today

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Initial impressions were positive, it's an accurate repro of shape and size and the lexan is nice and sturdy, good quality

But on closer inspection it is covered in little pin prick marks that aren't on the original shell, which I assume are part of their moulding process. They're pretty hard to photograph, but there is a line of three down the middle of the nose, one on the roof and the undercowl is covered in them

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This is going to be a runner shell using MCI repro stickers, so it's not a huge issue, but if the quality had been better I might have bought another and used it for display and left the kit original shell and stickers untouched in the box (as they seem to be so rare). And at £35 delivered it's not exactly cheap enough to just shrug it off either. 

So the overall verdict is a little bit Catchphrase; it's good, but it's not right. 

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Hi Juhunio,

you could also test a Penguin custom shell for the Tamiya Astute. I was heavily impressed of their quality on my Dyna Storm Repro shell.

There were some tiny spots with little imperfection, but fit and shapes were great. At least not as such tool prints as on the Kamtec...

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