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Old 01-27-2009, 06:38 AM   #4201
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Originally Posted by John St.Amant View Post
Something isn't right thats for sure ! I wouldn't be happy either. It has to be either a poorly drilled chassis or a bad suspension mount ie... 1XA or 1F.
Remive them and measure from the 3mm hole to the outside of each one. And discrepencies will show you the bad part.
Sorry,I dont get what you mean. Measure from which hole?
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Old 01-27-2009, 06:42 AM   #4202
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I have just finish building my car, now its sitting on my set up board. My problem is rear toe. Left arm read 4deg toe in while right arm read 3deg toe in. I m using the stock suspension block 1XA (rear front) and 1F (rear rear). From the chart at Thard forum it should read 3.5deg toe in. I have tried loosening the suspension block screws hoping to align it better but the it still reads 4deg and 3 deg. Can anyone suggest anything? I m using Hudy Set Up System BTW.
I experienced the same thing...even with my 415 MRE and MSXX. I asked Tamiya about it, they said there must be something wrong with the Hudy gauges.

I gave up. I never noticed a difference on the track, but that doesn't make it right.
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Old 01-27-2009, 06:48 AM   #4203
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I have the Hudy set-up system as well, and I experience the same problem on the rear regardless of chassis and suspension mounts. I have measured everything on the car carefully, and concluded that it must be the set-up system.

I think that the Hudy system is more "bling" than "quality" - it really is not any better than any other (significantly cheaper) setup system.

Conclusion - do not worry too much about it, just drive and see how it feels.

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Originally Posted by dameetz View Post
I have just finish building my car, now its sitting on my set up board. My problem is rear toe. Left arm read 4deg toe in while right arm read 3deg toe in. I m using the stock suspension block 1XA (rear front) and 1F (rear rear). From the chart at Thard forum it should read 3.5deg toe in. I have tried loosening the suspension block screws hoping to align it better but the it still reads 4deg and 3 deg. Can anyone suggest anything? I m using Hudy Set Up System BTW.
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Originally Posted by sohlman View Post
I experienced the same thing...even with my 415 MRE and MSXX. I asked Tamiya about it, they said there must be something wrong with the Hudy gauges.

I gave up. I never noticed a difference on the track, but that doesn't make it right.
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Old 01-27-2009, 06:49 AM   #4204
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Sorry,I dont get what you mean. Measure from which hole?
More than likely one of the suspension mounts is bad . Measure from the hole that is used to attach it to the chassis to the outer edge. it should be the same from side to side . Also look and see if the pivot point is machined correctly. If they are symetrical then the chassis holes need to be measured . ( I doubt thats the issue ) But who knows . You have it in front of you . The problem may not be very obvious but ... I can't see the car or the parts . Nor do I have the ability to draw it . I bet tryhard can If you ask him nicly .

And as for the hudy ... the toe measurements depends alot on your ability to allign the groves. Not by holding it at the end of the channel that guides the measuring plate. For correct toe the lines need to overlap perfectly. And yet still there may be slop in the car or the tool. Mine was 3.5 deg per side.
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Old 01-27-2009, 11:30 AM   #4205
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I would be suprised if it's an issue with the chassis drilling, mainly as they are CNC cut and drilled... not much to go wrong there, not saying it doesn't happen though. The chassis holes should all be the same distance from the centre line, that goes for the suspension blocks and the bulkheads... it's part of the clever flex of the 416

As for the suspension blocks, first you need to measure is the distance between the screw holes. They should be the same. An easy way to make sure they are lining up is to bolt the two blocks together, just take a couple of screws and go straight through one and into the other (keeping the flat sides against each other). If you have any misalingment between the two, you'll find it there.

If there ok, well... there's not much more you can do. Try swapping the blocks round on the car too, giving F/XA (3.5 deg toe out). If it's something on the car, you should see it reversed, with 4 on the right, and 3 on the left.... If it's still the same sides, then it's probably the setup gear.

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Old 01-27-2009, 04:12 PM   #4206
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I would be suprised if it's an issue with the chassis drilling, mainly as they are CNC cut and drilled... not much to go wrong there, not saying it doesn't happen though. The chassis holes should all be the same distance from the centre line, that goes for the suspension blocks and the bulkheads... it's part of the clever flex of the 416

As for the suspension blocks, first you need to measure is the distance between the screw holes. They should be the same. An easy way to make sure they are lining up is to bolt the two blocks together, just take a couple of screws and go straight through one and into the other (keeping the flat sides against each other). If you have any misalingment between the two, you'll find it there.

If there ok, well... there's not much more you can do. Try swapping the blocks round on the car too, giving F/XA (3.5 deg toe out). If it's something on the car, you should see it reversed, with 4 on the right, and 3 on the left.... If it's still the same sides, then it's probably the setup gear.

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Ok I ll try that. I will also try another set up system (not Hudy). I ll post my findings again here.
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Old 01-28-2009, 01:53 AM   #4207
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No matter what you do there is always a tiny bit of tolerance. It is nature of any manufacturing process and CNC is not immune to it (although it is better than most mass production processes). I have often found that a binding suspension arm can be freed up by shifting the suspensions blocks away slightly. So the same method can be used to fix your problem. I would do one or both of the following:

1) Slightly loosen screws on XA block and shift the block as far left as possible. Keep in this position and tighten the screws back up.

2) Slightly loosen screws on F block and shift the block as far right as possible. Keep in this position and tighten the screws back up.

Try step 1 first and measure. If not enough, then do step 2 as well. Should do the trick...
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Old 01-28-2009, 02:19 AM   #4208
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Originally Posted by John St.Amant View Post
Are your rear tires worn out ?
Seriously I think you may be going the wrong way with that droop screw .
Go back to 4mm in the rear .
Tyres arent the issue, it was doing it with brand new absolutes. Hopefully I'll get it back to a reasonable state and can go back to a bit more droop
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Whats your ackermann setting? And how many shims are under your rear link, inner and outter? If you've been playing with droop and it's not working, you can try something else. Also, what front spring are you running?
5mm ackerman, 3mm under both sides of the rear camber link (.5 under the blocks), and silver HPI springs all around mounted on the same holes that Rheinard ran at the worlds

Last night I made the following changes:
  • Raised the front rc and added some anti dive (.5 under the front front block and 1mm under the front rear)
  • Put the HPI blue springs on the rear
  • Went from 400wt to 450wt oil all around, with 2mm rebound and no foam spacers
  • Shortened the rear wheelbase by 1.5mm

I need to detweak it and set the droop, then I'll give it a run over the weekend. Basically the first 2 points were to take away the lift off o/steer, the shock oil is just because I think 400 is too light, and the wheelbase was to bring back some rotation...
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Old 01-28-2009, 06:40 AM   #4209
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Originally Posted by veecee View Post
No matter what you do there is always a tiny bit of tolerance. It is nature of any manufacturing process and CNC is not immune to it (although it is better than most mass production processes). I have often found that a binding suspension arm can be freed up by shifting the suspensions blocks away slightly. So the same method can be used to fix your problem. I would do one or both of the following:

1) Slightly loosen screws on XA block and shift the block as far left as possible. Keep in this position and tighten the screws back up.

2) Slightly loosen screws on F block and shift the block as far right as possible. Keep in this position and tighten the screws back up.

Try step 1 first and measure. If not enough, then do step 2 as well. Should do the trick...
You are absolutely right, after trying everything including using another set up system, its still reads 4deg left 3deg right. It turns out that Hudy set up is good afterall.Then I realign the blocks a few times, right now I m getting approximately 3.75 left and 3.5 right. I try to realign the blocks again tomorrow, this rear toe problem already took me one and a half day to solve.
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Old 01-28-2009, 06:54 AM   #4210
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Off throtle oversteer . Sounds like you dont have enough rear droop to me but I'm not there so.... 4mm is a start and 5 mm would actually be less droop. you may need more .. Like 3mm instead. I know that sounds backwards but the # is absolute but actually negative in reference to the bottom of the chassis. Also the anti-dive you refered to is backwards . All you did was take out 0.5 deg caster. Anti-dive would be higher in the front of the arm as opposed to the rear .

Last edited by John St.Amant; 01-28-2009 at 08:12 AM.
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Old 01-28-2009, 07:41 AM   #4211
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Tyres arent the issue, it was doing it with brand new absolutes. Hopefully I'll get it back to a reasonable state and can go back to a bit more droop

5mm ackerman, 3mm under both sides of the rear camber link (.5 under the blocks), and silver HPI springs all around mounted on the same holes that Rheinard ran at the worlds

Last night I made the following changes:
  • Raised the front rc and added some anti dive (.5 under the front front block and 1mm under the front rear)
  • Put the HPI blue springs on the rear
  • Went from 400wt to 450wt oil all around, with 2mm rebound and no foam spacers
  • Shortened the rear wheelbase by 1.5mm

I need to detweak it and set the droop, then I'll give it a run over the weekend. Basically the first 2 points were to take away the lift off o/steer, the shock oil is just because I think 400 is too light, and the wheelbase was to bring back some rotation...
If nothing else works for you, one thing you can try is rear camber gain. Keep the 3mm under the outer rear hubs. But for the inner links, reduce it down from 3mm to 2mm or even 1mm. This'll help keep the rear end planted down in those tight corners.

Let us know if you find the problem/solution.
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Old 01-28-2009, 07:48 AM   #4212
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I'm fighting the same problem, thanks for all the info guys.
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Old 01-28-2009, 12:20 PM   #4213
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Originally Posted by John St.Amant View Post
Off throtle oversteer . Sounds like you dont have enough rear droop to me but I'm not there so.... 4mm is a start and 5 mm would actually be less droop. you may need more .. Like 3mm instead. I know that sounds backwards but the # is absolute but actually negative in reference to the bottom of the chassis. Also the anti-dive you refered to is backwards . All you did was take out 0.5 deg caster. Anti-dive would be higher in the front of the arm as opposed to the rear .
Your droop quote is right, i.e. a higher figure = less droop... but by the sound of it, thats what Craig needs. Less rear droop will help to transfer less weight forward... giving less off power steering.

As for the anti-dive, actually he's correct. 0.5mm under the rear block gives anti-dive, 0.5mm under the front block gives kick-up.
But there is the associated castor change still as you correctly point (IIRC 0.8mm under the block = ~1 change).

@ Craig... I think the rear wheelbase change maybe too much... I personally found the car a struggle with the shorter wheelbase, suprisingly it was lacking mid corner rotation! With the longer rear wheelbase, whilst it is longer, your also moving the weight balance forward, which does aid steering in general.
I think your probably spot on with the other changes though... I do have one theory for you.

You say you were running silvers F/R, on the leaned in holes. It's possible that running the shocks so leaned in, whilst in the inital part of the travel it feels quite soft and gives good grip, when it gets higher travel (such as turning in for tight corner), that the spring is stiffening up to such a point that the rear tyres lose grip...
Like you've mentioned you've changed, you could try a softer spring, but also run it higher up on the tower, making it more linear in it's travel. I know a lot of people I've been racing with have liked tamiya blues either in hole 4 or 5 on the tower, over whites leaned in more.
It's just a thought, and something I'm going to attempt to have a little play around with this weekend.

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Old 01-28-2009, 12:32 PM   #4214
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I had gone to no droop in the rear at all and someone told me that could be causeing my issue. I added some droop back in and it got much better. I can still see the front of my car dive hard though off power and went to stiffer springs in front and that made it better also. Unfortunately I made this bit of progress too late and broke the right front c hub and knuckle and didn't have spares to test it further. I just wanted to pass along my experience with the rear droop. I thought it sounded backwards too, but it did actually help.
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Old 01-28-2009, 12:41 PM   #4215
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what happened there is that you "rode the droop screw" I've had it a few times before, where basically, as you go through a corner highly loaded, and then try and turn some more, the inside suspension hits the droop screw, which rapidly unloads the tyre causing the car to snap round.

Droop is basically a compromise, between running enough so you generate enough weight transfer, (so you don't ride the screws), and not so much that you have huge amounts of weight transfer... it seems that between 4-6mm on a gauge is pretty much the range to be working in on the 416

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