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Xray T4 '13

Old 01-07-2014, 10:29 AM
  #5326  
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Originally Posted by rcguyfpr
I need help to setup a T4 for VTA.

I ran a T2, T3, VBC D05 in VTA, and got them to dial without issue. I recently switch to T4, and I have a hard time to make it work for VTA.

Track: Norcal Asphalt
Springs: RSD silver F/R. Also tried 2.9/2.7 or 2.9/2.5
Shock oil: 350/350. Also tried 45/45
Toe: F toe out 1. Rear toe in 3
Camber: F -2, R -1.5. also tried R -2
Gear diff: 1k front spool
Roll center: F mid hole 1mm shim. R outside hole no shim.

No matter what I do, the car just super loose in the rear. I have to drive it really carefully or else it just spin out.

This same car works great in 17.5 with RSD silver springs and 350 oil.

Any suggestion?
Where is the car spinning out? Entry, exit, on power, off power?
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Old 01-07-2014, 10:50 AM
  #5327  
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Originally Posted by rcguyfpr
I need help to setup a T4 for VTA.

I ran a T2, T3, VBC D05 in VTA, and got them to dial without issue. I recently switch to T4, and I have a hard time to make it work for VTA.

Track: Norcal Asphalt
Springs: RSD silver F/R. Also tried 2.9/2.7 or 2.9/2.5
Shock oil: 350/350. Also tried 45/45
Toe: F toe out 1. Rear toe in 3
Camber: F -2, R -1.5. also tried R -2
Gear diff: 1k front spool
Roll center: F mid hole 1mm shim. R outside hole no shim.

No matter what I do, the car just super loose in the rear. I have to drive it really carefully or else it just spin out.

This same car works great in 17.5 with RSD silver springs and 350 oil.

Any suggestion?
I'm assuming that you're running VTA using the rule set that requires a 1550 gram minimum weight. Since the T4 is a very light car, a lot of weight has to be added to the chassis to fully comply with the rules...

My question is - where is the additional weight placed on the chassis? If it's too far rearward I could see the car being a handful, and very difficult to drive.
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Old 01-07-2014, 11:56 AM
  #5328  
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I have 10g on bumper, 20g by steering, 30g in front of motor. The rest behind battery and motor. I did about the same location for t3 and t2.

Spin out in mid corner, off power.

Thx.
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Old 01-07-2014, 12:40 PM
  #5329  
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Originally Posted by rcguyfpr
I have 10g on bumper, 20g by steering, 30g in front of motor. The rest behind battery and motor. I did about the same location for t3 and t2.

Spin out in mid corner, off power.

Thx.
Diff oil could be too light (I use 3K), or the rear of the car is rolling off of the inside rear tire, which overloads the outside rear. You could add anti-squat to the lower rear arms, shorten and angle the rear camber links or widen the rear track width - any of those techniques should help the problem...
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Old 01-07-2014, 01:37 PM
  #5330  
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Originally Posted by oeoeo327
Diff oil could be too light (I use 3K), or the rear of the car is rolling off of the inside rear tire, which overloads the outside rear. You could add anti-squat to the lower rear arms, shorten and angle the rear camber links or widen the rear track width - any of those techniques should help the problem...
thx. will try on 3k diff. about time to open up that diff
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Old 01-07-2014, 01:57 PM
  #5331  
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Originally Posted by rcguyfpr
I have 10g on bumper, 20g by steering, 30g in front of motor. The rest behind battery and motor. I did about the same location for t3 and t2.

Spin out in mid corner, off power.

Thx.
What is your droop set to?

What is the total amount of weight added to the car? What spur/pinion? (defines how far back the motor is). I think oeoeo327 might be on to something.

Also, I'd reduce your rear toe-in. 3* is more than should be necessary for VTA. Every little bit less drag will help in the straights. More inboard toe-in can actually increase off-power steering, so reducing it could help.

-Mike
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Old 01-07-2014, 04:42 PM
  #5332  
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Originally Posted by Dan Hamann
I watched you adjust just about everything but your driving. When traction comes up like it did, you have to adjust your corner entry strategy as well. You can't bomb the car into the corner and scrub for turn in like you can on lower traction, you have to widen your corner entry, push brake to set the car, and then carve the corner. That, and stiffening the flex in my car to add to the predictability of the chassis is where I gained time this past weekend. Nothing else.
In Andrews words, my 2012 was much faster and better handling. This '13 with the rsd v2 kit the car is pushy and loose, rolls up in the sweeepr floats in the hairpin. hesitates in the corners.
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Old 01-07-2014, 05:13 PM
  #5333  
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Originally Posted by Boostinswifty38
In Andrews words, my 2012 was much faster and better handling. This '13 with the rsd v2 kit the car is pushy and loose, rolls up in the sweeepr floats in the hairpin. hesitates in the corners.
curious, is this on carpet? If so, can you post your setup, as I would like to see it.
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Old 01-07-2014, 06:24 PM
  #5334  
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Yes indoor carpet. New rsd chassis. 1mm droop front, 2 rear. 1mm shim on the back front lower hinge pin blocks, front front shims and all rear shims removed, 4 degrees of rear toe (car squared up leading into the straight much better vs. 3.25), 5mm ride height all around, stock t4 springs (tried rsd yellow/silvers-car felt lazy), 350 shock oil, 1,000cst rear gear diff, front gear diff 2.5mil cst. Upper links medium length in the rear, 4mm outside shim, 2mm inside on bulkhead. Front camber links full Long, 1mm shim outside at c hub, 2mm inside at bulkhead. Cut too deck up front to the "dot", all screws in. Arms up front spaced even/center, thin shim behind rear arms, thicker shim infront of them. Dcj's up front. 50mm axles rear. +.75 wheel hexes up front, standard rears. 1 deg. Toe out up front. 1deg. Front camber, 1.5 rear. Front shocks 1 hole down from all the way out, rear shocks one hole up from all the way down. T3 hard front bumper, sweep 32 tires (spec), need electronics?

Sorry if this is confusing, I don't have a setup sheet to fill in and post. If I am missing something let me know.
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Old 01-07-2014, 06:30 PM
  #5335  
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Odd, i had the exact opposite experience with the stock t4 vs RSD chassis. My t4 was pushy and slow in corners while my RSD has wonderful traction everywhere and has so much steering that I had to dial some back out.
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Old 01-07-2014, 06:37 PM
  #5336  
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Try this...

-2.3 springs all around.
-Narrow up the front by using stock hexes. Mid camber lengths. Take out the shims completely on top of the front/rear bulkheads.
-3.5mm read toe with the rear as narrow as you can make it. Try 2-3k rear gear diff oil.
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Old 01-07-2014, 06:40 PM
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Leave the rest? Put the shims back in the front and get rid of the anti dive? What rsd springs are most like the 2.3? I have both rsd spring kits.

Only issue I face is Wednesday tracks have a ton less grip then the MMR challenge race had.
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Old 01-07-2014, 07:10 PM
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I've got my suspension blocks shimmed up 1mm all around. No anti dive. Try having no shims at all on any of the bulkheads. Should add some steering. I'm also running 2 dot inserts up front instead of 1dot. Narrows up the car .5mm each side.

Blacks are the closest to 2.3s, I think. Maybe try blue fronts black rears and see how that feels. Don't use the progressive springs IMO. Made my t4 unpredictable on our technical carpet track.

Also, I dislike the t4 with a gear diff up front. Makes the car feel lazy mid corner to me. I prefer thicker rear diff oil for more steering with a spool up front. I just couldn't get used to a front diff.

Last edited by hyujmn; 01-07-2014 at 07:20 PM.
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Old 01-07-2014, 08:50 PM
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Thanks! I'll see how mantid these changes I can implement tomorrow asking grip levels are the same.
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Old 01-07-2014, 09:18 PM
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Yeah, I was typing that on a phone, but now I've got a keyboard in front of me. With a gear diff up front, the car had pretty good entry steering but felt really laggy mid corner, especially during a sweeper where I would have to drive carefully rather than really being able to hammer it around. I felt a better fix was thicker rear diff oil and putting the spool back up front.

Also, if it's still rolling, you could try backing off the droop in the rear to 1mm or 1.5mm and laying the rear shocks all the way down.
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