heretic

My buddy www.overrc.com pointed out to me that discrepancies in toe-in readings could come from wheelbase issues. His shrewd diagnosis was that our setup stations don't have a centerline point of reference and therefore the station works with the assumption that the slider toe-in protractor travels on a line perfectly perpendicular to the centerline. A tiny bit of wheelbase variation, less than you could actually feel when driving (say a hub carrier that is molded with the hub 0.2mm too much on one side, giving a 0.4mm L-R difference when mirrored) could thus potentially cause you to have inaccurate toe-in readings.

I am not saying this is necessarily the case for you Niznai, of course, but if it was, you could chase an asymmetry in toe-in where there is none. HTH

niznai

That's a very good point, but then the defect could not (or should not) be consistently replicated when hubs, suspension arms and so on are swapped with other parts. Not sure if you read my entire saga, but at some point I replaced the Tamiya suspension (arms, hubs, camber links) with Xray items (on the Tamiya bottom plate chassis) and the toe difference was still there.

More to the point, the problem should transfer to the other side if you swap the entire suspension setup left to right. In my case, the problem was consistent on the same side (I assign the problem to the side that had a different toe to what the blocks should have set by Tamiya's own documentation).

axle182

iTrader: (18)

I think I now understand why I refuse to put a toe gauge on the rear anymore lol. I too remember seeing different numbers. I am not as diligent as you Niznai, I just turn a blind eye these days. With other setup tweaks, I can make my car do what I want so I am happy

Talking about holding onto older cars, after selling one of my 417's I dragged out the old 416 I had on the shelf for some mod running. Ran well with a set of aeration shocks. I then found a spare 417 Smokem motor mount, and went to town on my CNC machine. here is the final product on the left, raceberry 417 on the right. 80mm width, 2mm top and bottom. Short shocks also. So 416 front and rear suspension, steering, and 417 motor mount, and a chassis shaped like the RB. First race this Friday

niznai

That is exactly what I need. Can you cut a chassis and drill it on that contraption? And more importantly, can you countersink the holes?

I have a chassis design I would like to test.

PS. I have never had this toe problem before (or after), and I have here some rather crappy old clunkers, and some oldies from the nineties and a whole bunch of off-roaders. None has that problem.

axle182

iTrader: (18)

Yep, the pic showing the cutting is a first test. I now countersink first as the countersink's are the true locator for the screws, not the screw hole.

PM me, I can cut whatever you want. Im a Cad designer by trade, so I can design what you want too.

heretic

My bad. On the one hand swapping the whole suspension with other brands and getting the same result does indeed seem to point towards an asymmetry located on the chassis/ suspension holders.

On the other hand, the swapping left to right with the same brand parts does not in itself point towards the chassis because it depends on which plastic part we are talking about. An hypothetical +0.5 degree misalignment on a hub carrier would become a -0.5 degree when mounted on the other side. No matter which way around you mount a hub like that, you will get about 1 degree of "overall" misalignment showing always on the same side. However, on an A-arm, +0.5 will stay +0.5.

I guess you've thought about that and tried all possible combinations, just throwing ideas out there in case it lights a bulb. Too bad the Tamiya and Xray outer hinge pins don't have matching diameters (I think?) otherwise you could have tried the Xray arms with the Tamiya hub carriers and vice versa.

FWIW my personal rule of thumb would be to always trust anything Xray over any other brand when it comes to tolerances, so that would bring me to your very conclusion: the problem is somewhere on the chassis

g12314

iTrader: (6)

Awesome work! I too keep a collection of "older stuff" as backups for TCS racing. Still a big fan of the 416 platform and would be awesome to have a modern narrow chassis plate for it.

Jimmy

axle182

iTrader: (18)

I have everything to make a narrow 416 chassis and upper deck. PM me if your interested

Qatmix

Looks great!

mos-leung

May i known which model/brand of your CNC?

niznai

Yep, I trust Xray for accuracy in machining too, which is why I used the aluminium Xray zero toe rear hubs to "master check" everything in the end, and the toe difference is still the same. To make sure the Xray arms didn't introduce their own defects, I measured, then swapped the arms left to right and measured again. As expected, the toe difference is the same and on the same side.

I also used Tamiya's rear aluminium hubs I have from the TA05R and these are symmetrical (zero toe as well) so you can turn them around and toe shouldn't be affected. Same result.

Nah, I don't think there's a car out there that has been measured so much in its short life like this one. Like I said, it is a first for me, and I doubted everything else (my eyes, tools, my assembly skills, callipers, everything) before I doubted Tamiya.

Meh. I am still not sure where the problem is exactly (I took everything off the chassis plate and tried to measure distances between holes using callipers and millimetre paper to triangulate every hole in relation to the others and I found some minor differences, but like I said, by that point I could swear I could see little green people from Mars, so I gave up), maybe it's just a compound accumulation of tolerances in the most unfavourable way, a freak stroke of bad luck on my part. I found a way to deal with it, that's important, and I am happy now with my car.


Coming back to axle's statement above, it is true the countersink chamfer will ultimately decide where the screw comes to rest when tight, but the thing is, the hole and its countersink should be absolutely concentric. The screw heads should be absolutely concentric too. I do usually inspect visually screws and holes after some minor mishaps in the past, and I didn't find problems there (or no real problems). Again, here Xray is absolutely stellar int heir manufacturing. I am yet to see a hole which is not perfectly lined up with its countersink chamfer. Not that Tamiya's are (or not visibly) but on Tamiya plates you can see with the naked eye the chamfer is variable in diameter from one hole to the next.

Back to manufacturing, I found the most difficult problem is to cut a proper countersink on a hole. I did it a few times, using hand tools, but I absolutely hate it, and carbon simply blunts your countersink in no time. Some of the bits I used were blunted in one hole. Maybe there is a secret to it (I have tried using various fluids, water works best). Speed is also crucial. You need good countersink tools (and they cost a packet!). But I can't say I mastered it and will go to great lengths to avoid it.

yifuqiao

iTrader: (13)

Got a set of TRF sway bar set today.
I honestly think Sway bars are kind of useless for this car.
It doesn't really "connect" left and right side of the suspension.
With shock off, if I push up one end, the other end doesn't move much if it moves up at all.
A arm is moving freely, maybe a tiny bind, but I followed the manual, so it can't be that wrong.
Currently... my sway bars just act like additional spring. But I really want the "sway bar" effect .
My local track is a high bite carpet track, traction roll is pretty common with our spec tire. I was hopping stronger sways would give me a better feel .
Does anyone have same problem with the sway bards?

vlad_sa

You are certainly doing it wrong from what you describe...
Sway bars are absolutely mandatory!

yifuqiao

iTrader: (13)

You are right, I want sway bar.
But I don't think you totally get what I am trying to say.

I think somehow, sway bar on my car only acts as an additional spring.
It does't have that left - right end link connecting effect.

PDR

iTrader: (31)

I'm sure there's other articles out there, but here's the first one I could find on how to install/setup swaybars on a TRF car. It's from a 417, but the approach isn't significantly different:
https://tchub.wordpress.com/2012/07/...-build-part-5/

Paying attention to the little details is important. For example, making sure the grub screws are not too tight, but not too loose. If you're still having trouble, find an experienced hand at your local club to check it out.

Phil.