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Discussion Starter #1
My Son and I are at our wits end, trying to resolve our traction issues. Our car hooks good on average 1 out of every 3 runs. We have a C4 with a brake, and launch at 3500rpm with 275/50/15 Nitto drag radials at 15psi. On a bad launch, it seems to hook for a second, then break loose, where my Son has to burp the throttle, which kills the 60’ time. I’m not sure if this video will post, but this was our last run yesterday evening, and it broke loose. Not sure if you can zoom in and slow motion the video, but if you can, it looks to me like it’s wrinkling the tire, and rebounding the rear causing it to loose traction? We’ve tried bumping up the air pressure to 17-18, but it won’t hook at all then. below is our suspension set-up

Rear: UPR lowers and adjustable uppers, Strange 10 ways (currently set on 6), stock springs with 2 coils removed, 4.10 gear,

Front: UPR Chromoly K-member, Strange 10 ways with coil over conversion (currently set on 3, but in the video, we bumped them up to 4 to try and correct, but it got worse)

This car only makes about 340hp, weighs 2740 (without driver), and in my opinion, should not be experiencing these issues. Looking for opinions as to why it won’t hook???

 

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Start with the easiest thing, I’d swap the tires. Try a MT ET street R and you won’t have any more issues. Sounds like the suspension is working. You could also make sure your pinion angle is where you need it to be. Check Baseline suspensions website for the opinion angle info.


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Discussion Starter #4
What is your good 60 and your bad 60?
When it doesn’t spin, our 60’ is low 1.5s, when it breaks loose like that, 1.7s. When it hooks we are 11.80s, when it breaks loose we are 11.90s to 12.00s. Car has the original 180k 302 with just heads, cam, 700 double pumper, 4000 stall converter, no power adders.
 

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Discussion Starter #5
Start with the easiest thing, I’d swap the tires. Try a MT ET street R and you won’t have any more issues. Sounds like the suspension is working. You could also make sure your pinion angle is where you need it to be. Check Baseline suspensions website for the opinion angle info.


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We’ve talked about that, and regret not going with the MTs to begin with. The only thing that has stopped us from doing it is we are in the process of adding a 150 shot, and We may go to a 28” tire. I say that because with the 4.10 gear and the current 26” tire, we are hitting the traps at 6700 rpms. Can’t imagine what rpm it would trap adding a 150 shot??? Either way, we will be going to MTs. If I knew a set of MTs would cure this problem, I would run out and buy a set today???
 

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If you were closer I’d give you mine to try. I’ve heard the same story with the Nitto 555Rs. The NT05R are supposedly better hurry the MT are in my opinion always superior for the strip. Another thing Nd to check is like I mentioned the pinion angle. I know sometimes when the suspension is unloading and the angle is off that can cause traction to break, or something along those lines. I know on the:

https://www.baselinesuspensions.com/info/pinionangle.htm

this explains it all, and it makes sense. Keep us updated with what you find.


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Set the front struts to full soft. This will give them the least possible rebound damping, allowing the front end to rise higher, which will increase weight transfer to the rear tires.

If the front suspension is running out of droop travel on launch, you can increase the number of spacers between the upper spring perch and c/c plate bearing in the front.

Raise the front and rear ride height of the car. This increases the cg height, which causes more weight transfer to the rear tires on launch. Install stock springs in the rear suspension. Don't ever cut them. Unless the car has a problem with lifting the front tires too high on launch, you never want to lower the ride height.
 

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My Son and I are at our wits end, trying to resolve our traction issues. Our car hooks good on average 1 out of every 3 runs. We have a C4 with a brake, and launch at 3500rpm with 275/50/15 Nitto drag radials at 15psi. On a bad launch, it seems to hook for a second, then break loose, where my Son has to burp the throttle, which kills the 60’ time. I’m not sure if this video will post, but this was our last run yesterday evening, and it broke loose. Not sure if you can zoom in and slow motion the video, but if you can, it looks to me like it’s wrinkling the tire, and rebounding the rear causing it to loose traction? We’ve tried bumping up the air pressure to 17-18, but it won’t hook at all then. below is our suspension set-up

Rear: UPR lowers and adjustable uppers, Strange 10 ways (currently set on 6), stock springs with 2 coils removed, 4.10 gear,

Front: UPR Chromoly K-member, Strange 10 ways with coil over conversion (currently set on 3, but in the video, we bumped them up to 4 to try and correct, but it got worse)

This car only makes about 340hp, weighs 2740 (without driver), and in my opinion, should not be experiencing these issues. Looking for opinions as to why it won’t hook???

I think the instant center and tire selection needs attention. Nittos are not a great tire for drag racing. Stock springs in the rear with 2 coils cut may be throwing the IC off and giving you very little anti squat. Also if it hits the tire and then unloads I think a double adjustable shock may be the answer as the rear end extends and then contracts (squatting) too quick. Where's the pinion angle set at?
 

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Shortening the spring by cutting it, always makes the spring stiffer to some degree. This is not what you are going to want to do in most drag race situations.

Also with the car lowered, it is much more likely that the nose of the differential housing is going to hit the pinion snubber. That will definitely cause a big chnage in rear tire loads, followed by wheelspin. I would install a shorter pinion snubber, so it is only hit when there is a lot of tire hop.

 

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Discussion Starter #10
I think the instant center and tire selection needs attention. Nittos are not a great tire for drag racing. Stock springs in the rear with 2 coils cut may be throwing the IC off and giving you very little anti squat. Also if it hits the tire and then unloads I think a double adjustable shock may be the answer as the rear end extends and then contracts (squatting) too quick. Where's the pinion angle set at?
Pinion angle is -3* from crankshaft centerline
 

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didn't have any luck either hooking with 275/60/ 15 Nitto 555r, switched to Hoosier Quick time pro 27x10.5 and hook way better now off the line.
 

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Better tires are the answer. In the meantime try exploring tire pressures in the 13.5 to 14.5 range. When I look at the video I don't see any rise of the rear of the car to plant the tires. I think you should plot out your rear suspension so you know what direction to go.
 

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nitto 275/60/15 hook great... on my 02 V6 car. Would never use them at the track though. Check out that baseline suspension link above.
 

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You have anti squat values over 100%, meaning the rear separates at launch, which is a good thing. I have the same issue has you on an ET Street. Still ironing it out, but i think a double adjustable shock would help you. Some tighter compression settings on the rear would slow down the tire when it tries to pop back up and unload.

Joe
 

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Discussion Starter #16
You have anti squat values over 100%, meaning the rear separates at launch, which is a good thing. I have the same issue has you on an ET Street. Still ironing it out, but i think a double adjustable shock would help you. Some tighter compression settings on the rear would slow down the tire when it tries to pop back up and unload.

Joe
You have anti squat values over 100%, meaning the rear separates at launch, which is a good thing. I have the same issue has you on an ET Street. Still ironing it out, but i think a double adjustable shock would help you. Some tighter compression settings on the rear would slow down the tire when it tries to pop back up and unload.

Joe
We switched to a 275/60/15 MT ET Drag Pro Radial, and problem solved. It now launches hard and straight, and with approx 10 runs on it, no spin at all!
 

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Set the front struts to full soft. This will give them the least possible rebound damping, allowing the front end to rise higher, which will increase weight transfer to the rear tires.

If the front suspension is running out of droop travel on launch, you can increase the number of spacers between the upper spring perch and c/c plate bearing in the front.

Raise the front and rear ride height of the car. This increases the cg height, which causes more weight transfer to the rear tires on launch. Install stock springs in the rear suspension. Don't ever cut them. Unless the car has a problem with lifting the front tires too high on launch, you never want to lower the ride height.
I'm just catching up in this forum and found this jewel. Jack has never led me astray and I'm now rethinking my setup. I was complaining previously how high the rear of my car sits with the Team Z rear drag coils. Hmmm....maybe they know a thing or two?
 

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We switched to a 275/60/15 MT ET Drag Pro Radial, and problem solved. It now launches hard and straight, and with approx 10 runs on it, no spin at all!
How did the taller tires effect your ET and MPH?
 

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I have gone 1.29 60' on a 26x8.5 Hoosier with the front end tied down at 3150 lbs. A lot of it depends on how the engine delivers the power. If the engine is weak at low rpm, then you have to add that into the equation. If the engine wants to bog with a dead hook, then that needs to be addressed. Much more than just chassis has to considered. Especially if you make a lot of power.
 
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