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Car Drifts Left During Burn Out #2706448
10/13/19 04:07 PM
10/13/19 04:07 PM
Joined: Feb 2011
Posts: 264
Spanaway, Washington State
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patosmith Offline OP
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patosmith  Offline OP
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Spanaway, Washington State
Can anyone give me some ideas on where to look for reasons why my 72 Challenger drifts to the left during a burn out?
I get into the water box, begin my burn out but before i can really get the slicks warmed up, I have to lift because the car gets out of shape. Then it spins at the launch.
I have the same issue when I run with street tires so I don't think it is the slicks.
Here is my set up:
Car runs around 12.1 to high 11's in 1/4.
Big block
727 Automatic with 3000 stall converter. No trans brake.
Dana 60, 4:10 gears and Detroit locker.
Cal Tracs mono leafs and adjustable shocks.
M/T ET Street Radial Slicks

Shocks were set pretty light during a test pass but I then stiffened them up. Same setting on both. Same results.
Air pressure for the slicks were both at 17. Also tried 18 and 19.
Cal Tracks are adjusted to "just touching" on both sides.

I put the car on jack stands. Weight being on the suspension. I took measurements and the car is square.
I took diagonal measurements LF to RR and RF to LR.

I am going to check the slicks to make sure they measure out the same just to be sure but I have the same problem with street tires .

Any ideas on what else I should look for?

Re: Car Drifts Left During Burn Out [Re: patosmith] #2706450
10/13/19 04:32 PM
10/13/19 04:32 PM
Joined: Jan 2003
Posts: 26,222
Oregon
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AndyF Offline
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AndyF  Offline
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Oregon
Get the car scaled. You probably have a weight bias. You could also have an issue with the differential. Maybe your Detroit Locker has a little bias built into it. Measure the diameter of each tire, sometimes they vary by quite a bit.

Re: Car Drifts Left During Burn Out [Re: patosmith] #2706453
10/13/19 04:48 PM
10/13/19 04:48 PM
Joined: Nov 2013
Posts: 466
Nashville, Tennessee
Tempest Offline
mopar
Tempest  Offline
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Posts: 466
Nashville, Tennessee
Because we have torsion bar front suspensions, the front can have an effect on the rear and weight distribution. I have a narrowed, back half coil over rear suspension car. I had to adjust the front in addition to the rear for the car to go straight.

Re: Car Drifts Left During Burn Out [Re: AndyF] #2706456
10/13/19 05:08 PM
10/13/19 05:08 PM
Joined: Aug 2003
Posts: 33,574
Bend,OR USA
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Cab_Burge Offline
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Bend,OR USA
[quote=AndyF Measure the diameter of each tire, sometimes they vary by quite a bit. [/quote] iagree scope get them within a 1/4 inch on the circumference with a cloth seamtress tape using air pressure, if possible luck
If they are more than a 1/4 inch now and you can't get them near that try swapping the big tire with the small tire on opposite sides.
Good luck, let us know what you find out wrench
Do you have a manual valve body trans? If so are you starting in 2.nd gear and shifting into high gear as soon as the rear tires start to spin? If not try that and get the rear tire spinning as fats as possible to get them hot sooner scope up

Last edited by Cab_Burge; 10/13/19 05:11 PM.

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: Car Drifts Left During Burn Out [Re: patosmith] #2706530
10/13/19 09:00 PM
10/13/19 09:00 PM
Joined: Mar 2008
Posts: 46
TX
RiskyRickey Offline
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Posts: 46
TX
ck front brakes one not holding letting your car get sideways .I had same problem. Found a bad brake hose

Re: Car Drifts Left During Burn Out [Re: RiskyRickey] #2706608
10/14/19 07:02 AM
10/14/19 07:02 AM
Joined: Mar 2006
Posts: 7,739
MI, usa
dvw Offline
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dvw  Offline
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MI, usa
What are you scale weights? I'd be the RR is lighter than the LR.
Doug

Re: Car Drifts Left During Burn Out [Re: dvw] #2706759
10/14/19 03:33 PM
10/14/19 03:33 PM
Joined: Aug 2003
Posts: 33,574
Bend,OR USA
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Cab_Burge Offline
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Bend,OR USA
Originally Posted by dvw
What are you scale weights? I'd be the RR is lighter than the LR.
Doug
iagree Every near stock Mopar from 1962 on that I have weighed all four corners on had the least amount weight on the right rear, every one whiney shruggy
I've raced cars with spools in the rear end like that did not move around in the water box, a lot of them shruggy work


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: Car Drifts Left During Burn Out [Re: patosmith] #2706775
10/14/19 04:45 PM
10/14/19 04:45 PM
Joined: Feb 2003
Posts: 15,019
Mesa, Arizona
dart4forte Offline
I Live Here
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Posts: 15,019
Mesa, Arizona
Possible you have a bent or twisted axle housing?

Re: Car Drifts Left During Burn Out [Re: RiskyRickey] #2706845
10/14/19 09:04 PM
10/14/19 09:04 PM
Joined: Jan 2003
Posts: 5,733
Hamilton, Ontario Canada
Magnum Offline
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Magnum  Offline
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Hamilton, Ontario Canada
Originally Posted by RiskyRickey
ck front brakes one not holding letting your car get sideways .I had same problem. Found a bad brake hose


+1


69 Super Bee, 93 Mustang LX, 04 Allure Super
Re: Car Drifts Left During Burn Out [Re: Magnum] #2707071
10/15/19 05:01 PM
10/15/19 05:01 PM
Joined: Jan 2003
Posts: 5,030
Pikes Peak Country
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TC@HP2 Offline
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Pikes Peak Country
Would rear axle thrust cause this?

Re: Car Drifts Left During Burn Out [Re: TC@HP2] #2707098
10/15/19 07:21 PM
10/15/19 07:21 PM
Joined: Feb 2011
Posts: 264
Spanaway, Washington State
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patosmith Offline OP
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patosmith  Offline OP
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Spanaway, Washington State
I thought about the weight issue too.
I will need to find someone local that has scales so i can check on that.

Would it help any to soften up a shock on one side?

Also, someone asked about the axle housing. This rearend is a new Moser Dana 60 so i hope it's not bent or twisted!

I hadn't thought of the front brakes. That will give me something to check also.

I don't think I would be able to get back out to the track this year to test. Seattle rainy season is just about upon us!

I will spend the winter checking on why it is doing this.

I appreciate everyone's input. Good stuff.

I will post what I find.

Re: Car Drifts Left During Burn Out [Re: patosmith] #2707285
10/16/19 01:10 PM
10/16/19 01:10 PM
Joined: Aug 2003
Posts: 33,574
Bend,OR USA
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Cab_Burge Offline
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Bend,OR USA
It wouldn't hurt to take two carpenter squares and set the car up on jack stands with both rear wheels remove and have someone help you use the carpenter squares push up tight the axles and use a tape measure to see how far apart the squares are measured out around 15 inches from the center of the axles under the car to the other square as close to the rocker panels in front of the rear end and then reverse the measuring to the rear and compare the results to see if it is wider (more than 1/8 inch) front or rear scope And then measure straight up and down to see if it is bent that way or not also up wrench


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: Car Drifts Left During Burn Out [Re: patosmith] #2707287
10/16/19 01:27 PM
10/16/19 01:27 PM
Joined: Mar 2006
Posts: 7,739
MI, usa
dvw Offline
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MI, usa
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Originally Posted by patosmith
I thought about the weight issue too.
I will need to find someone local that has scales so i can check on that.

Would it help any to soften up a shock on one side?

Also, someone asked about the axle housing. This rearend is a new Moser Dana 60 so i hope it's not bent or twisted!

I hadn't thought of the front brakes. That will give me something to check also.

I don't think I would be able to get back out to the track this year to test. Seattle rainy season is just about upon us!

I will spend the winter checking on why it is doing this.

I appreciate everyone's input. Good stuff.

I will post what I find.

Tightening the left torsion bar adjuster will jack weight to the right rear. As long as the car doesnt wheel stand this will help.
Doug

Re: Car Drifts Left During Burn Out [Re: dvw] #2707388
10/16/19 07:34 PM
10/16/19 07:34 PM
Joined: Jan 2003
Posts: 14,030
So Near, Yet So Far
topside Offline
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topside  Offline
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Posts: 14,030
So Near, Yet So Far
Aren't Caltracs supposed to be pre-loaded on the right ?



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