FF03 4GR with Peugeot 306 Maxi shell - Custom 4 Gear Transmission Rally Car

[Jonathon Gillham 4606]

1 minute ago, ThunderDragonCy said:

I'll be keeping this updated. For the standard car i can't recommend the arm upgrade enough. Those flipped front TA07/TRF419 arms transformed the handling of the car. 

If the 4 gear doesn't work i have a super compact three gear sketched out too. I also had a play with a 2 gear yesterday. It's super tight and limited on gearing, but it would be so light and free running. Only work considering if the counter-rotation of the 4 gear motor installation improves the car. The 2 gear rotates the motor the same way.

When you say flipped front arms - can you flip TA07 arms to change handling? How does it change things?

[ThunderDragonCy 7877]

1 hour ago, Jonathon Gillham said:

When you say flipped front arms - can you flip TA07 arms to change handling? How does it change things?

Only is really necessary and achievable on a fwd car with IFS. With the IFS the shock is actuated from the rear of the arm and the sway bar attached to the front. The opposite of a regular shock tower setup. So, to mount arms other than the reversible arms supplied with the kit, you need to flip them so the shock eyelets are on the inboard/rear, and the plastic sway bar ball attachment is towards the front. The big advantage i found with this when using the TA07/TRF419 arm shape is that the offset they have built in moves the front wheels forward 3mm when run flipped like this. On a front wherl drive car this is a big advantage because is effectively bring the motor closer to the front axle, improves the weight distribution and improves the handling. You couldn't do it on a TA07 because you couldn't attach the shocks or sway bar, and you don't need to either because you don't have the motor hung out beyond the front axle. 

[ThunderDragonCy 7877]

Exciting things happening. Ken from Cobra Products sent me this pic earlier

How cool is that?!! 

Also Shapeways delivered the gearcases already despite saying my order would take until may! They are sitting waiting for another couple of days in quarantine. 

Only thing now is the idler shafts i ordered from rcmart a few weeks back still haven't arrived. 

[ThunderDragonCy 7877]

Couple of things here. Firstly the Ride cut slicks arrived on these lovely cross spoke wheels yesterday. Don't they look great compared to race discs? Got these to save my sorex28s for racing now that i am doing lots of street running with this. Work really nicely, as you might expect of the ETS control tyre. More understeer than the sorex28, but they are very new. Going to run them a little more to scrub them in before chasing the setup. Highly recommended for onroad street running. 

Secondly, a bit ahead of when i hoped to spend the money is a Bittydesign HCF race shell. I smashed up the cheapo GTR shell i was using when the servo glitched and it hit a kerb and smashed and entire section of body off. Tough they are not! So, made sense to get the shell i was eventually going to buy anyway. Will cut slowly and carefully over the weekend and leave paint until the weather warms up again next week. 

[ThunderDragonCy 7877]

Shell cut and positioned on body posts

Looks so low and cool. Can't wait to paint and run it

[ThunderDragonCy 7877]

Shapeways came through with the gearcases so i gave them a trial fit. It fits! 

The motor plate fits the gearcase perfectly, but i made a couple of mistakes elsewhere. The body mount is about 5mm too far forward and the body mount holes aren't quite in the right place. I am not really surprised. It was really hard to get any kind of relative datum measurement between the car and the new gearbox and these elements. I have measured up and now i have the gearcase i was able to print out revised versions on paper to check. After a couple of tries i got it right and sent the revised drawing to Ken. Luckily Fibrelyte haven't made the brace yet so i have changed that drawing and haven't wasted a part. I also need to tweak the motor slots. They aren't quite right either. Nearly there though! 

[Jonathon Gillham 4606]

This is looking great!

How will the 4 gear change the car?  I have it worked out on my 2wd buggy with a midmount motor (in front of the rear axle, 3 or 4 gear trans).  Will this one with the 4 gear putting the motor in the front increase or reduce front grip?

[ThunderDragonCy 7877]

6 hours ago, Jonathon Gillham said:

This is looking great!

How will the 4 gear change the car?  I have it worked out on my 2wd buggy with a midmount motor (in front of the rear axle, 3 or 4 gear trans).  Will this one with the 4 gear putting the motor in the front increase or reduce front grip?

Thanks! It should improve the grip on throttle. This is eqiuvlent to the difference in a 2wd drive buggy of a 4 gear standup. The kit transmission is a 3 gear standup. So, in a 4 gear buggy the motor rotation gives more traction in low grip because squats the rear suspension. However, the flip here with it being fwd is that this rotation and squat on the suspension potentially gives the rear more grip too. If you think about it this way, if you look at the side of the car when you apply the throttle the motor forces effectively rotates the deck downwards between the wheels around the front driven wheels, thus transferring load to the rear on throttle. In a 2wd buggy the opposite is true, the 4 gear squats the rear and unloads the fronts, good for traction. A 3 gear does the opposite, tends to transfer load forwards, better front bite on corner exit. Because of the different arrangement of the fwd i am hoping for that weight transfer to more evenly load the car. 

[ThunderDragonCy 7877]

Last night was the big night! Having given up on the two lightweight idler shafts ever arriving from RcMart, i dug in the spares box and found the solid shaft leftover from putting hollow carbon shafts in my DT03. I chopped it down to 16mm, filed it off and got to work swapping over the transmission. Went fairly well, but some learning points too.

The gearcases required the usual prep; 3.1mm drill thorough the clearance holes for the screws, M3 tap in the 2.5mm holes for threads, tiny bit of xacto knife work in the idler shaft bores to get them to press in. 

So, here's the diff and idlers stacked. 

Black idler is a Tamiya reinforced from my FF03 as is the TA06 diff. The white idler is an RW Racing delrin item i found on ebay listed as being for TRF201. They share drivetrain parts. 

I got excited and put it together without taking any more photos, but there's not a lot to tell if you have put together a FF03, TA06 or TRF201 transmission before. This still retains the FF03 layshaft and spur gear mount. To increase the offset of the motor plate from 21mm to 24mm from the car centreline, i staggered the internals across in stages to move the whole layshaft/countergear assembly across 3mm. So, idler 1 is 1mm offset from the centreline, idler 2 is 2mm offset, layshaft 3mm. It reduces the gear mesh slightly, but not enough to be concerned i think. I did this because a motor is notionally 50mm long and this is as close to centred as i could get it. 

I tried installing my kimbrough 69t spur gear, which i had hoped would clear. I knew it was tight from the CAD though 

It does clear the driveshaft at rest (thankyou CAD model!) but at full compression the shaft catches. The FF03 has a surprisingly large amount of up travel! I also got the dimensions of the camber link mount (kit part M6) wrong on the CAD. This and the way it fits to the main bulkhead were the hardest parts to figure out sizes and clearances for. The camber link catches on the spur gear, but i also had to file down the motor plate tab a couple of mm to clear the camber link too. I also had to cut M6 to clear the gearcase. I knew i would, but the required clearance cut right through the edge of the M3 hole for the bulkhead mounting screw. This makes the whole thing squash out under the preload of the screw, so it's not as secure as it could be. It also needed splitting, which again, i expected, but the two things combined really reduced the stiffness. I also did this trial installation on a spare regular plastic part rather than the reibforced item i have. Maybe some careful dremmel work on the reibforced M6 would sort it? We'll see. It went together, but i think a bespoke part to replace M6 would be better in hindsight. 

With the 64t spur gear clearances are all much happier

You can see how close the motor plate and camber link are. Unfortunately for my 17t brushed setup, the smallest gear i can run on the 64t is a 37t pinion for 4.5 FDR, which is 17.5 brushless territory. I have a 17.5 to go in, but i had been hoping to keep a 5.5ish gear option for the brushed. 

Here's the complete installation from above. 

You can see on the top left a purple spacer. Both the bumper mount and body mount locations are as per kit in the side view, but with the additional layshaft offset, 3mm spacers are required on both to fit properly. 

And from the front

Everything else has come out as i designed, which is great. The motor sits right down on the tub, and just touches the suspension block and just clears the gearcase so it's pulled back as far as is possible with this chassis. Here's a video of it running. It sounds so smooth! 

I also got paint on my new shell over the weekend, so did a quick test fit. I reamed the post holes on the kit, so this means the body mounts on mine are bang on, which is nice! 

Core RC paint shonky as ever though. I love this neon carrot colour (i have adopted for all my race shells) but i had another case of propellant failure after 5 passes just like last time i used it, bought a can from a different shop and got that working for the whole can. I made the error of going for core rc silver to back it instead of tamiya. It's like glitter paint and really thin. Luckily this shell comes with lots of stickers. 

 

[ChrisRx718 4470]

Love it, keep up with the engineering work! Enjoy reading this thread.

Concerned about your comment ref. Core RC paint though, I bought some of their fluorescent paint to see if it was more resilient than the flakey Tamiya stuff...

[ThunderDragonCy 7877]

2 hours ago, ChrisRx718 said:

Love it, keep up with the engineering work! Enjoy reading this thread.

Concerned about your comment ref. Core RC paint though, I bought some of their fluorescent paint to see if it was more resilient than the flakey Tamiya stuff...

The neon carrot is WAY brighter than tamiya florescent orange, but it's thin and capricious. I usually back with tamiya silver which is fine, but it's not display quality

[ThunderDragonCy 7877]

Finished the shell last night. Thank goodness for big, interesting, die-cut decals. Big thumbs up to Bittydesign for this. 

 

 

[ThunderDragonCy 7877]

 

Reinforced chassis time! Except it seems i already had one. All the part numbers and stamps on my first chassis match the carbon chassis! I bought this secondhand, but it wasn't mentioned and all the other plastics were ABS. Weird. Anyway, tapping threads. 

Carbon rear stiffeners. Niiiiiice. 

 

Yeah Racing TA05 alloy servo mounts. Super nice, and done require the transponder stay to be included just to hold them on. 

 

[Tizer 606]

What servo is that? The white is cool!

[ThunderDragonCy 7877]

48 minutes ago, Tizer said:

What servo is that? The white is cool!

DM-S1211-M from Hobbyking. They were out of stock of my usual Trackstar D99X. This was the suggested alternative.

[Grotty Otty 868]

@ThunderDragonCy Really impressed with all your work on this, the gearbox is ace.

Can you tell me what part number those servo mounts are? My Google fu comes up short! It's the only part on my FF-03 that feels like it's made of too softer material. 

[ThunderDragonCy 7877]

1 hour ago, Grotty Otty said:

@ThunderDragonCy Really impressed with all your work on this, the gearbox is ace.

Can you tell me what part number those servo mounts are? My Google fu comes up short! It's the only part on my FF-03 that feels like it's made of too softer material. 

Thank you. I was surprised to find them. Thry were listed under FF03 hop ups on rcjaz. Part number is TA05-14/V2/LB. 3Racing part. 

[ThunderDragonCy 7877]

Finished (for now) and running. 

Soldered longer wires and bullet plugs on the motor and plugs onto the very short esc wires. Now it's 17.5 brushless. Pulls the 4.5 gear nicely, and with brakes set at 100% strength it slows down well enough too (very tall gearing reduces the braking effect of the motor). 

Found that the bumper fits snugly up against the shell, so refitted that and held it down with two old cva pistons. 

Gave it a run and was understeering a lot, so went back to setup. After trying various combinations i have ditched both sway bars for now. I lowered the front roll centre with 2mm spacers under the inner camber link balls, to give a bit more grip. Then i reset the cambers, toe and ride heights. 6.5 front, 7 rear (for street running. Would lower it a mm or so for racing), 0.5 deg camber front, touch of toe out. Runs nicely now and it puts the power down so nicely. You can nail the throttle really early in a turn. 

Nice. 

[ThunderDragonCy 7877]

Had a bit of time this morning so I have (hopefully) addressed the issues of the M6 part needing to be split to clear the gearcase. I modelled up the existing part best I could then edited it in the assembly until it cleared, then beefed it up a bit where possible. 

Also noticed my steering rack is very baggy when I transferred it to the new tub. The FF03 uses bushings in the steering wiper. Was looking for a replacement, but they're either very expensive (Tamiya XV01 carbon set) or have parts I don't need because I'm quite happy with the reinforced plastic steering arms. Then I noticed the Yeah Racing hop up set had a steering wiper with the ball studs centred using longer turnbuckles for the arms. This is a feature of almost all the chassis after the FF03 (my TA06 for example). So, I measured and modelled and came up with a bearing steering rack with centred ball studs. 

As parts they're very cheap when ordered together on Shapeways, but Shapeways have bumped up their shipping cost AGAIN, so now it's 10 bucks to ship $6.50 of parts! Anyone needing some Shapeways bits and are in the UK I would ba happy to order and split shipping!

 

[ThunderDragonCy 7877]

Couple of things. Firstly, i managed to club together with another member for the shapeways order so the above two parts are on their way. Went on a small shopping spree as a result and also have 730 bearings, m3x10 screws and 3x42mm aluminium turnbuckles on their way as well. Nice! 

Also, had a chance to fully charge the battery and get a proper long run in, driving on the estate roads around the block from me. I am very much enjoying the lack of traffic with lockdown! Ran for about 20 mins, and i am so happy with it. It is nice and stable and balanced, puts the power down well, even does lots of high speed s bends down the middle of the street without the back end getting away and turning into a tankslapper. Just lovely. Only slight negative is quite a lot of high speed understeer on the throttle. I have a high speed turn running through a T junction and use it full throttle running in and turn in and see if a car will run around. The FF03 now understeers wide to the poibt of having to back off to tighten the line, or lift on the way in then get back on the power. I am only bothered by this because the outdoor track i race at has a long full throttle sweeper. 

I will have a little play with setup to see if i can improve this, but right now i love the lower speed stability and precision, so maybe this is a trade off for the track? Slight lift for the sweeper, but really good on the infield? We'll see hopefully! 

Also worth noting that despite a lot full throttle running and hard accelerations (turning in the street kerb to kerb is effectively doing lots of hairpins) the motor was barely warm running blinky but 35 deg timing on the endbell, 4.5 FDR. After all that running the battery was still at 7.92V. The brushless is SO much more efficient than the 17t brushed. 

[ThunderDragonCy 7877]

Lunchtime project. Low profile sized servo tray, mainly because the HCF body rattles like mad against the kit servo tray because the shell has scooped out section doors, so it runs about 2mm from the tray and rattles against it when running. 

Would fit my TA06 as well. I am definitely getting to the "how much more can I hop up my cars" part of this lockdown situation!

 

[ThunderDragonCy 7877]

More chassis tuning. A quick check of my setup guides said to cure understeer i need to either raise the rear roll centre, or stiffen the rear springs as the first things to try. I don't have a spare set iof tamiya blue springs (the next up from the yellow on the car at the moment), but i could effectively make them stiffer by going back to the proper shock mount holes further outboard on the other side of the rear arms. Less leverage on the shock, effectively stiffer spring. However, that quite a lot of faff, so i took the 1mm spacers out of the inner arm balls (leaving 1mm spacer in) to raise the roll centre

It worked! Was pinned through the high speed corner i have in the street, but did not seem to noticeably affect the low speed. Oddly was pulling to the right quite hard under acceleration. Only thing i changed was putting new fancy ABEC3 bearings in the wheel axles because they were a bit baggy. They seem free. Odd. Anyway, loving this car. It's brilliant. 

[Nicadraus 6198]

Are there ABEC9 bearings for RC? I have a manual adult kickscooter (Oxelo Town 9) and replaced the stock ABEC5 bearing to race ABEC9 bearings. The difference is huge and freewheeling is just amazing. 

[ThunderDragonCy 7877]

4 hours ago, Nicadraus said:

Are there ABEC9 bearings for RC? I have a manual adult kickscooter (Oxelo Town 9) and replaced the stock ABEC5 bearing to race ABEC9 bearings. The difference is huge and freewheeling is just amazing. 

I don't know. I get my bearings from rcbearings.co.uk and after the stock option, there's ABEC5, then if you want better than that you are into ceramic bearings which are crazy money. 

[ThunderDragonCy 7877]

Felt bad that what started this adventure has laid unused since the race prep madness began. I reamed some new holes in my 306 shell to match the new post positions. It's pretty beat up now so i wasn't too upset about the extra holes. I would rather be able to use it. 

Looks quite fetching with the Ride wheels don't you think? Just looks so good!