Nasty Wheel hop with new axle
06-12-2007, 09:36 AM
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Nasty Wheel hop with new axle Just installed a 3.42 axle in place of the 2.73 on my 2000 TA. Now, with a real hard launch, I get very bad wheel hop, the whole back of the car seems like it wants to fall off. 
During normal driving, everything is fine. During the axle swap, I did install new cheap Monroe shocks (not monotube), in place of the deCarbons. Both sway bar endlink bolts snapped off, and were replaced by a new kit from Napa. Other than that, the car is pretty much stock, with just a few bolt-ons. Car is not lowered. With the 3.06 A4 1st gear ratio + 3.42 puts the overall first gear between 3.90's and 4.10 on an M6.
Any quick recommendations on something I missed during the install. (Don't think so but I'll ask anyway).
Do shocks make that big of a difference for wheel hop? I still have the old ones to swap back on if need be. Any other factors?
Any simple suspension upgrades to help out. I know upgrading springs, LCA's, panhard bar, swaybar etc would help out, but don't want to drop too much money into this. That's what the vette is for
.
During normal driving, everything is fine. During the axle swap, I did install new cheap Monroe shocks (not monotube), in place of the deCarbons. Both sway bar endlink bolts snapped off, and were replaced by a new kit from Napa. Other than that, the car is pretty much stock, with just a few bolt-ons. Car is not lowered. With the 3.06 A4 1st gear ratio + 3.42 puts the overall first gear between 3.90's and 4.10 on an M6.
Any quick recommendations on something I missed during the install. (Don't think so but I'll ask anyway).
Do shocks make that big of a difference for wheel hop? I still have the old ones to swap back on if need be. Any other factors?
Any simple suspension upgrades to help out. I know upgrading springs, LCA's, panhard bar, swaybar etc would help out, but don't want to drop too much money into this. That's what the vette is for
. 
06-12-2007, 10:11 AM
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Stock springs will be fine, if not optimal for you.
You may have worn LCA bushings.
What tires do you have?
Also, you may just need to adjust your launch. Although, I guess an automatic makes that a little more difficult.
After all that... Shocks, LCA's and Torque arm all have an effect on wheelhop.
You may have worn LCA bushings.
What tires do you have?
Also, you may just need to adjust your launch. Although, I guess an automatic makes that a little more difficult.
After all that... Shocks, LCA's and Torque arm all have an effect on wheelhop.
06-12-2007, 11:49 AM
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Originally Posted by OldeSkool
Stock springs will be fine, if not optimal for you.
You may have worn LCA bushings.
What tires do you have?
Also, you may just need to adjust your launch. Although, I guess an automatic makes that a little more difficult.
After all that... Shocks, LCA's and Torque arm all have an effect on wheelhop.
You may have worn LCA bushings.
What tires do you have?
Also, you may just need to adjust your launch. Although, I guess an automatic makes that a little more difficult.
After all that... Shocks, LCA's and Torque arm all have an effect on wheelhop.
I haven't had much practice yet controling the launch (Just replaced the rear this weekend). LCA bushings may be an issue. What about the effect of shocks?
With TC off, it hops bad. With TC on, I havn't got any hop yet. I'll be down at Atco tonight and will possibly try some different launches.
Last edited by nj02vette; 06-12-2007 at 12:02 PM.
06-12-2007, 03:17 PM
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Shocks deal with damping up and down movement. They have an affect on how quickly the weight shifts from the front of the car to the back under launch-- how quickly the spring compresses. They also affect how quickly the spring rebounds. Though I am no drag racer, I believe it is generally preferred to have less compression damping in order to gain more weight transfer. I don't know what the preferred rebound characteristic is for drag racing. With rear shocks especially.. you have to decide whether you want something that works well at a drag strip or something that works well for cornering or is comfortable to drive etc.
that being said... the shocks do make a difference in the wheel's hopping, but I don't believe that they will prevent it from starting to hop. The wheel starts to hop because of a sort of tug-of-war that comes from slack in the suspension... On a stock hp car with street tires... it could come from worn bushings. On a high hp car with sticky tires, it could come from the stamped LCA's or from a weak torque arm.
Now for my personal theory
If the car is at rest and suddenly, power goes to the wheels, the axle pushes on the lca's. If say the bushings are too squishy, they get compressed. They then push back, the axle, still under power pushes back again and so on until the car has built up enough momentum that the power is no longer pushing so hard on the lca's that they spring back. This pushing and pulling seems to me to cause varying levels of torque to be applied to the axle and a sloppy torque arm will allow the rapid ups and downs in torque to turn into ups and downs of the wheels.
So since a shock may dampen or reduce wheel hop, I don't know that there is a shock that would completely eliminate it... it would probably be better to try to stop it from happening before it comes down to the shocks.. probably the best place to look is first at your LCA's to prevent that slack from springing back and forward. Or at a torque arm.. a shorter one perhaps that will supposedly put more downward force on the rear end and reduce flex.
that being said... the shocks do make a difference in the wheel's hopping, but I don't believe that they will prevent it from starting to hop. The wheel starts to hop because of a sort of tug-of-war that comes from slack in the suspension... On a stock hp car with street tires... it could come from worn bushings. On a high hp car with sticky tires, it could come from the stamped LCA's or from a weak torque arm.
Now for my personal theory
If the car is at rest and suddenly, power goes to the wheels, the axle pushes on the lca's. If say the bushings are too squishy, they get compressed. They then push back, the axle, still under power pushes back again and so on until the car has built up enough momentum that the power is no longer pushing so hard on the lca's that they spring back. This pushing and pulling seems to me to cause varying levels of torque to be applied to the axle and a sloppy torque arm will allow the rapid ups and downs in torque to turn into ups and downs of the wheels.
So since a shock may dampen or reduce wheel hop, I don't know that there is a shock that would completely eliminate it... it would probably be better to try to stop it from happening before it comes down to the shocks.. probably the best place to look is first at your LCA's to prevent that slack from springing back and forward. Or at a torque arm.. a shorter one perhaps that will supposedly put more downward force on the rear end and reduce flex.
06-12-2007, 09:24 PM
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Thanks for the info. I didn't think the shocks would cause that much difference, but I'm not an expert so I figured I'd ask the question.
The LCA are stock, and I can upgrade from the stamped version with rubber bushings to a bar stock unit with poly bushings.
Didn't get to Atco tonight, skies opened up.
But will probably try next week.
The LCA are stock, and I can upgrade from the stamped version with rubber bushings to a bar stock unit with poly bushings.
Didn't get to Atco tonight, skies opened up.
But will probably try next week.
06-13-2007, 12:35 AM
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let me caution you before you purchase LCA's
The stockers are actually designed to twist. when both wheels go up and down at the same time, going straight over a speed bump, everythings cool. But when one wheel goes over a bump and the other doesnt.. whatever is holding the axle to the car needs to be able to twist a little.
If you go with tubular or boxed LCA's, be sure that there is at least one point where twisting can occur. For instance, poly bushing / spherical bushing combos allow the articulation that is needed by having a rod end at the axle and still have a fairly comfortable ride with polyurethane at the body. Also... you have even less flex because there is one less "soft bushing"
The stockers are actually designed to twist. when both wheels go up and down at the same time, going straight over a speed bump, everythings cool. But when one wheel goes over a bump and the other doesnt.. whatever is holding the axle to the car needs to be able to twist a little.
If you go with tubular or boxed LCA's, be sure that there is at least one point where twisting can occur. For instance, poly bushing / spherical bushing combos allow the articulation that is needed by having a rod end at the axle and still have a fairly comfortable ride with polyurethane at the body. Also... you have even less flex because there is one less "soft bushing"
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06-13-2007, 09:00 AM
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In support of OldeSkool:
Here is a post I made in a recent thread:
Here is a post I made in a recent thread:
Originally Posted by VIP1
The rear axle needs to articulate. Poly limits this articulation. The stock LCAs are stamped steel units designed to flex to allow for articulation. A solid tube with poly ends limits this articulation which can lead to unpredictable behavior. This limiting of articulation is what people often refer to as bind. In an extreme/rare situation this bind, can damage the LCA mounts. Rod ends allow for more articulation than the stock pieces and remove the compression/squirm of the stock rubber bushings, but they also transmit more NVH (Noise Vibration Harshness). A good compromise is a poly/rod setup. The body side is poly to help limit some NVH and the axle side is rod to allow for the articulation.
If this is a drag car, you can get away with poly/poly. If you are more interested in handling, go with rod/rod or poly/rod.
I mentioned poly/rod above, but there was a thread a while back about rubber/rod. That is a very rare component. If I remember correctly, it wasn't normal rubber, but something with a higher durometer (close to poly in performance, but will transmit less NVH).
Not all rod ends are created equal. Some rod ends have a Teflon lining to allow to operate more smoothly and last longer. Also, rod ends will eventually loosen up and require replacement. How long varies with the type of rod end and the driving involved.
If this is a drag car, you can get away with poly/poly. If you are more interested in handling, go with rod/rod or poly/rod.
I mentioned poly/rod above, but there was a thread a while back about rubber/rod. That is a very rare component. If I remember correctly, it wasn't normal rubber, but something with a higher durometer (close to poly in performance, but will transmit less NVH).
Not all rod ends are created equal. Some rod ends have a Teflon lining to allow to operate more smoothly and last longer. Also, rod ends will eventually loosen up and require replacement. How long varies with the type of rod end and the driving involved.
