Wheel-hop, Anti-squat and Roll Oversteer

[Full_Tilt]

So my car wheel hops... quite badly. Ive probably actually spun the tires only a handful of times, all the other times it has started hopping and Ive had to let out immediately fearing Ill hurt the driveline.
The cure for this seems to be replacing the flimsy lower control arms and possibly even lowering the rear mounting point of the lower control arms in order to create more anti-squat. I like the idea of more anti-squat as it should allow you to hook up and accelerate out of the corner earlier.

Here is where my question comes in. If I understand correctly, shouldnt angling the control arms more upward, as you would to create more anti-squat, also induce more roll oversteer? I always though that they tried to make the control arms on a live axle angle downward from the rear, so that when the body rolled one way, the axle would steer the other way, inducing understeer.

So, do you just take the added roll oversteer with the anti-squat and tune it out with the rest of the suspension? or do you keep the stock mounting locations and live with the squat?

 

[Whiskey11]

Antisquat is created by lowering the axle side of the LCA. Doing so moves the car towards roll oversteer as the outside wheel compresses through horizontal it actually moves the rear axle rearward and when the inside wheel extends it brings it in closer. Since the front wheels and the rear wheels are facing in opposite directions it adds more rear steer, thus more rear oversteer.

Angling the LCA's up towards the axle decreases antisquat and moves the handling bias towards roll understeer as the exact opposite of what happens above happens.

If you have problems with wheel hop it is usually due to soft bushings that bind. I would think that adding more antisquat would cause wheel hop to get worse not better. Reducing it certainly gets rid of it (as is evident by the absence of wheel hop in my lowered 'stang) at the expense of forward bite. That said, the easiest method of getting rid of wheel hop is stiffer bushings or spherical bearings in the LCA's. Antisquat will help with wheel spin though.

 

[Full_Tilt]

Antisquat is created by lowering the axle side of the LCA. Doing so moves the car towards roll oversteer as the outside wheel compresses through horizontal it actually moves the rear axle rearward and when the inside wheel extends it brings it in closer. Since the front wheels and the rear wheels are facing in opposite directions it adds more rear steer, thus more rear oversteer.

Angling the LCA's up towards the axle decreases antisquat and moves the handling bias towards roll understeer as the exact opposite of what happens above happens.

Thats exactly what I was thinking, but wasnt 100%.

If you have problems with wheel hop it is usually due to soft bushings that bind. I would think that adding more antisquat would cause wheel hop to get worse not better. Reducing it certainly gets rid of it (as is evident by the absence of wheel hop in my lowered 'stang) at the expense of forward bite. That said, the easiest method of getting rid of wheel hop is stiffer bushings or spherical bearings in the LCA's. Antisquat will help with wheel spin though.

I see. So more ridgid lower control arms, with good bushings alone should be the best bet for decreasing the hop.

Also, are any of you roadcourse guys going for anti-squat and adjusting accordingly for the roll oversteer? or is that just left to drag racers?
Id love to have antisquat and good handling, but that may be asking too much, haha.

 

[Whiskey11]

Don't forget that you can tune antisquat with the UCA as well. Raising the chassis side will accomplish a similar goal without effecting roll steer.

I haven't played with any of it so what I am saying is mostly from my understanding of how our suspension works.

Lots of antisquat can introduce wheel hop under braking in road course environments.

Here is a thread on another forum that deals with calculating antisquat but more importantly are some of the other posts about antisquat in track cars:

http://www.corner-carvers.com/forums/showthread.php?t=39717

 

[Philostang]

The stock rear LCAs are not in themselves "flimsy." That's marketing b.s. The bushings in those arms, however, are very soft. Your wheel hop is from bushing deflection, not from the LCAs flexing. For consideration, look at the FR500S cars; they have those same "flimsy" LCAs and do just fine...of course, you can bet they're not running the same bushings in them.

As for using anti-squat (from LCA as opposed to the UCA), some folks do it on the road course. I run a bit, but nothing like what you'd see from the drag crowd. Of course, I could be just another internet moron, so take it as you will. However, of more significant note, Kenny Brown has lower relocation brackets as part of his offerings and highly recommends them (along with a host of other things). His own demo cars run them and run fast. Think what you may of him, but KB is not a knuckle dragging drag-strip guy; he's a road racer through and through. My point being that yes you can run anti-dive in the rear successfully, but there are also many ways to skin the cat.

Best,
-j

 

[BMR Tech]

So my car wheel hops... quite badly. Ive probably actually spun the tires only a handful of times, all the other times it has started hopping and Ive had to let out immediately fearing Ill hurt the driveline.
The cure for this seems to be replacing the flimsy lower control arms and possibly even lowering the rear mounting point of the lower control arms in order to create more anti-squat. I like the idea of more anti-squat as it should allow you to hook up and accelerate out of the corner earlier.

Here is where my question comes in. If I understand correctly, shouldnt angling the control arms more upward, as you would to create more anti-squat, also induce more roll oversteer? I always though that they tried to make the control arms on a live axle angle downward from the rear, so that when the body rolled one way, the axle would steer the other way, inducing understeer.

So, do you just take the added roll oversteer with the anti-squat and tune it out with the rest of the suspension? or do you keep the stock mounting locations and live with the squat?

There are some very good replies in this thread.

I must ask, what is your ride height at? There are so many things that play roles when setting anti-squat in cornering applications.

FWIW, I have been selling more and more Upper Arm Mounts and Relo Brackets to corner carvers, year after year.

I am not so sure why, but Relocation Brackets have always been considered a "drag" racing component, but that is not true. I will assume that since BMR released them way before anyone else, that they just automatically took that position.

 

[Full_Tilt]

The stock rear LCAs are not in themselves "flimsy." That's marketing b.s. The bushings in those arms, however, are very soft. Your wheel hop is from bushing deflection, not from the LCAs flexing. For consideration, look at the FR500S cars; they have those same "flimsy" LCAs and do just fine...of course, you can bet they're not running the same bushings in them.

As for using anti-squat (from LCA as opposed to the UCA), some folks do it on the road course. I run a bit, but nothing like what you'd see from the drag crowd. Of course, I could be just another internet moron, so take it as you will. However, of more significant note, Kenny Brown has lower relocation brackets as part of his offerings and highly recommends them (along with a host of other things). His own demo cars run them and run fast. Think what you may of him, but KB is not a knuckle dragging drag-strip guy; he's a road racer through and through. My point being that yes you can run anti-dive in the rear successfully, but there are also many ways to skin the cat.

Best,
-j

Thanks for your input. What you say about the LCAs makes a lot of sense.
Im going to look into replacement bushings, I certainly dont want to buy some fancy billet LCAs for 300 bucks if I dont have to.

There are some very good replies in this thread.

I must ask, what is your ride height at? There are so many things that play roles when setting anti-squat in cornering applications.

FWIW, I have been selling more and more Upper Arm Mounts and Relo Brackets to corner carvers, year after year.

I am not so sure why, but Relocation Brackets have always been considered a "drag" racing component, but that is not true. I will assume that since BMR released them way before anyone else, that they just automatically took that position.

I agree, lots of good info in this thread. This is the most impressive section of this forum imo.

Im currently at stock ride height (2011 base GT). I may lower it eventually, but when I do it wont be by much, Im interested in making it handle, not look cool.

 

[BMR Tech]

I do not think Relocation Brackets would do much of anything for you at stock ride height on that car.

I assume the front is about 28.5" and the rear 29.4"???

As for lowering, a quality set of 1" - 1.5" drop springs and geometry correction, would increase your handling substantially.

 

[Steedagus]

I do not think Relocation Brackets would do much of anything for you at stock ride height on that car.

I assume the front is about 28.5" and the rear 29.4"???

As for lowering, a quality set of 1" - 1.5" drop springs and geometry correction, would increase your handling substantially.

Agreed, we do not normally recommend relocation brackets at stock ride height either.

 

[SoFL05GT]

.....

 

[Captainstr8edge]

For what its worth I got the J&M LCA's for $99 from American Muscle. they certainly helped but didn't get rid of it completely, I then did an UCA and bracket and wheel hop is completely gone. I'm stock height.

 

[Full_Tilt]

I looked at those J&M LCAs. The price is awesome, but Im wondering fif its worth it to get the ones that have spherical bushings on one end.

 

[Philostang]

Before I went to full sphericals, I had the J&M LCA with their poly-ball joint. I loved them. They took care of my wheel hop entirely, but I wasn't trying to launch super hard nor did/do I have uber-power to lay down.

I was also surprised at how good they looked after two years of daily driver duty and half-dozen track events per summer. I've seen other arms whose poly bushings looked destroyed after a summer of hard track use on a buddy's car.

Best,
-j

 

[sheizasosay]

I looked at those J&M LCAs. The price is awesome, but Im wondering fif its worth it to get the ones that have spherical bushings on one end.

I'm selling my J&M street billet LCA's with the polyball bushing. It has articulation that you won't get in a standard poly joint.

Much of this topic was covered not long in a thread I started http://www.s197forum.com/forum/showthread.php?t=88124

I have my relocation brackets off right now and I will expect they will go back on after my shocks are rebuilt. Just getting a baseline right now. I just put my car up on jackstands an hour ago. My UCA bolt hole is about to be changed to as it is in the non-stock position and is giving me antisquat(not that AS is bad, but I'm baselineing) even though my LCA's are angle 5+ degrees in the understeer direction. I have been taking measurements and documenting everything. You can use an angle finder or there is an inclinometer app for the iphone that is extremely accurate. I have checked it against my mechanical angle finder that you see BMR using for setting pinion angle and my measurements that I calculated using geometry formulas all verify it. That app is the shit! I can tell you that relo brackets are widely used by road racers. The boss302S has them from the factory. That should tell you something. Look for yourself-http://www.svtperformance.com/forums/2012-boss-302-mustang-373/757330-boss302s-11.html
post 263 is the one. Also, I have the Grassroots Motorsports magazine Feb 2012 and has road racing mustangs from Moss Muscle, Saleen Speedlab, 2 others and then also Paul Brown from Tiger Racing's Boss 302S which I have attached a picture of it. Paul Brown's lap time was 2:03 around VIR. The other players were several seconds behind save one other Boss 302 and his time was 2:02-2:03. With what I got going, if I put the relo's back in, my LCA angle will be 2.3 degrees in the oversteer direction. The LCA's move up and down with the loading. I have been told you ideally want it setup so if the LCA's move say 2 degrees in normal travel then you would want the LCA's anled down 1 degree so it will travel through neutral to understeer to minimize the roll steer effects. Obviously how much your travel is depends a mostly on spring rates and dampening, but here is an example: http://www.youtube.com/watch?v=SV8QjXsrg7Y

And that's my .02

 

[DILYSI Dave]

After going to a full spherical front suspension on my Civic, I'm a HUGE believer in getting rid of compliance. The car just became so much more predictable, changes became more nuanced, etc. The mustang build is going to be full spherical from the onset. Now, I've never had spherical in a street car. I could see it being more harsh, though that typically doesn't bother me. My bigger concern on a street car would be wear. On an autox car, the amount of wear that the sphericals see is pretty negligible. On a street car, I assume that they would be a far-too-often consumable.

 

[Fuerte]

After going to a full spherical front suspension on my Civic, I'm a HUGE believer in getting rid of compliance. The car just became so much more predictable, changes became more nuanced, etc. The mustang build is going to be full spherical from the onset. Now, I've never had spherical in a street car. I could see it being more harsh, though that typically doesn't bother me. My bigger concern on a street car would be wear. On an autox car, the amount of wear that the sphericals see is pretty negligible. On a street car, I assume that they would be a far-too-often consumable.

Only thing stopping me from going full spherical is I heard they wear out quickly. Nosie isn't am issue with me just to any one else in the car.

Sent from my SCH-I535 using Tapatalk 2

 

[DRock]

I run BMR's Poly/ROd end LCA's (the non adjustable ones) along with their relo brackets and really think they helped a lot. The LCA's alone got rid of all the wheel hop I had. DONE. ANd the Relo Brackets made the car feel like it had a lot more "bite" when getting on the gas leaving a corner shall we sy. I would do them all over again without even thinking.

 

[Norm Peterson]

Your car looks lowered ↑↑↑.

By how much?


Norm

 

[Norm Peterson]

FWIW, I have been selling more and more Upper Arm Mounts and Relo Brackets to corner carvers, year after year.

Greater understanding of rear suspension geometry, especially when lowered, would be my guess.

I am not so sure why, but Relocation Brackets have always been considered a "drag" racing component, but that is not true. I will assume that since BMR released them way before anyone else, that they just automatically took that position.

Probably because the drag racers have been concerned about correcting their "instant center" (more specifically, the Side View Instant Center) for far longer than the average corner-carver has been pondering matters of roll steer correction. The drag strip guys have even coined the term 'separation', which is utterly meaningless when you're cornering.

Even though the two geometric effects are directly related, neither camp seems to have seen enough value in the other guy's mods to also consider doing them until fairly recently (and tuning the amounts to suit). Part of the problem with relo brackets as far as a corner carver is concerned is that either the available hole relocations tend to be too low for the intended ride height, or that the ride height required to make the existing hole locations work is too low for other reasons (such as bump travel or roll center heights).

For the S197, the OE amount of roll steer at the OE ride height is actually quite close to neutral, which is good out of the box for the corner carver at the expense of the drag racer and his anti-squat requirements.


Norm

 

[BMR Tech]

Norm, I agree.

To be honest, the stock IC/AS settings are pretty decent for a drag racer. This also depends on tire compound, diameter and transmission type.