Wheel Hop Correction Thread

[Preloader]

I've learned that adding any decent amount of power to the Sonic introduces wheel hop under hard launching. The wheel hop can be detrimental to all of the drivetrain components. Including the weak design of the M32.

Lets talk about what wheel hop is really caused by. When a good amount of force is applied to the front tires, they actually will try to pull the lower control arms forward before the car has a chance to come forward with them.

This causes the arms to pull towards the front center of the car, creating extra toe-in. The toe-in brings the rotational force off of its perpendicular axis to the desired straight line acceleration, causing the tires to slip and jump back to their original position, grab again, pull toe-in, jump and slip, grab, jump and slip.

When this happens at peak power levels it's like a roto-hammer pounding on everything between the engine and the wheels.

Here is an informative article:
mc²racing-wheel hop

The biggest cause of hop on the Sonic is the poor performance of the rear lower control arm bushing. It sits on a vertical axis and the rubber has large voids. This allows way too much movement under launch loads.

I'd like to contact TTR or DDMW about a polyurethane replacement, but in the meantime, I'm going to take theenico's valuable advice and fill the voids in the stock rubber ones with DIY poly.

I hope to see some dramatic results soon.

 

[Eric Smit]

footballs.

 

[Preloader]

This is the idea. Pic is of an upper, but it's very similar to our lower bushing.

 

[wingman]

Don't you mean the LCA's are pushed backwards? Them being pushed forward would mean you are driving in reverse no?

 

[Preloader]

No. Picture the rear of the car bolted to the ground. Now picture the front wheels trying to take off hard. Where are they going to go. Forward, and also turn inward because of the play in the rear LCA bushing. The weight of the car is the anchor until the inertia travels to the entire mass.

Remember, in FWD, the front wheels pull the car. The car doesn't pull the front wheels like they do in RWD.

 

[wingman]

Ok I'm trying to make as much sense of that as possible with my lack of imagination but I think it makes sense. You're talking newtons law sh!t

 

[Preloader]

Yes. It's actually a combination of all 3 of Newton's laws of motion.

 

[Preloader]

So the Urethane compound is about $30 through McMaster Carr. I'm gonna try to do my LCAs while I have the subframe out for the tran swap.

 

[laborsmith]

Preloader, there are no magic answers but a quality lsd will be close. And in the end if you maintain the course you are on, the lsd will not only help but be required.

Front wheel drive or rear wheel drive, efficiently getting the engine power to the ground is the goal. Both Quaife and WaveTrac provide good answers. I am partial to the WaveTrac but either would work well for anyone trying to get the use of maximum power in the most efficient manner.

There are a lot of ways to reduce wheel hop but based on my studies all take a back seat to a quality limited slip differential and all are made more effective when used in conjunction with same.


Laborsmith

 

[Preloader]

If you read the link in post#1, it specifically says that LSD does not cure wheel hop. Wheel hop on FWD is primarily a suspension issue. That doesnt mean I'm not interested in LSD, but it's low on my list until I get rid of this hop.

Also considering replacement parts are not readily available for the M32s, I likely won't be rebuilding my broken one. And will need to purchase yet a 3rd M32 for when I brake my MZ0.

I absolutely refuse to go back to the track without a swap-ready replacement in my garage.

So as you can see, the next $700-900 I spend will be on another gearbox, not extra goodies for said box.

 

[GeneralZod]

I read it as all the things mentioned including a LSD will be needed.

I wonder how much power you are planting....

 

[River_Rat]

If you read the link in post#1, it specifically says that LSD does not cure wheel hop. Wheel hop on FWD is primarily a suspension issue. That doesnt mean I'm not interested in LSD, but it's low on my list until I get rid of this hop.

but, the link does state that an LSD, and even race tires, can increase the acceleration threshold at which wheel hop occurs. whether this threshold will be sufficiently increased to offset the increase in hp is anybody's guess. while it is an indirect remedy, the mitigating effect could be substantial. it could buy some time while further suspension engineering is performed.

 

[Preloader]

Valid points, and the good thing about the diff on the M32 is that it is an easy swap, only 9 bolts. #28 and 30 in the diagram.

But like I said my financial priorities will be to first acquire yet another MZ0 replacement, then I can beat this one up with my tightened LCA bushings and maybe get a couple ETs in before it breaks.opcorn:

 

[laborsmith]

1) You can feel the pulling difference between a Sonic w/ an LSD and a Sonic w/o an LSD. Literally.

2) If an LSD is marginally effective, why do super cars and performance equipped muscle cars come with them standard?

3) Following up on 2, why do performance oriented drivers replace their stock differentials (w/ or w/o LSD) with aftermarket ones?

Many moons ago I posted suspension improvements such as strut tower bars and under carriage braces would help reduce wheel hop and in fact I lobbied Steve Toussaint (ISM) to become a SOF sponsor vender because he carries these for other cars and I figured would for the Sonic once they became available. No one makes these parts for the Sonic and meanwhile his attention is directed to cars other than the Sonic.

Under carriage braces will definitely help but no one is making them. A Quaife or a WaveTrac will also help AND they are being made, the Quaife in England and the WaveTrac in California.

Once you have driven an LSD equipped turbocharged Sonic you will understand the point I am trying to make. And you will wonder why it took you so long to do so.


Laborsmith

 

[Preloader]

I don't doubt that you are right LS. It's just not gonna happen before Friday when I do the trans swap. But you can bet on the next swap, an LSD will be included.

 

[theenico]

At the track where you launch on a grippy surface with both wheels pointed straight ahead, an LSD will do little to nothing for the toe changes that cause the hop.

As I was typing that, another thought occured. Try setting your front toe dead ahead or even just a scosche (1-2 degrees) out. That should also help mitigate the pigeon toe effect.

 

[Preloader]

Fussing with the toe alignment is mute until the bushing slop is corrected.

But I'm glad you reminded me about alignment. I have done a total drop of 3", swapped front c/o's to Pedders, changed wheels and tires and have not had my alignment done.

The camber from the drop is borderline ridiculous. And while none of those should have affected toe, it couldn't hurt to find out where I'm out and make sure they're adjusted properly.

 

[theenico]

I you've gained negative camber, then you definitely have more toe in than what it left the factory with. The tie-rods are longer than the control arms, so the toe can change a fair amount with changes in camber.

As low as you've gone, I'd definitely have it checked.

 

[Preloader]

Will do, I need to pick up some crash bolts too.

 

[MPFab]

I just had my alignment done after installing cam bolts. I'm only on Eibachs, but needed the extra adjustment they offered to get these big-ass wheels I'm trying to stuff under the stk fenders on. I maxed them out on the negative side figuring it would be easier to start from there since they would only have to be move one direction to get where I wanted to be.
Since the tie rods are on the backside of the spindle, neg camber increases toe in. Let me tell you, the toe was WAAAYYY off from where it needed to be. I don't have the print out infront of me, but it was like the front wheels were trying to make an imaginary "cow catcher" at the nose of the vehicle with the angle there were projecting.
FYI, I set up everything I own with zero toe. I find this helps with tire wear when additional camber is dialed in, and the car is more responsive to directional changes, without being squirrely.
If your primary concern is drag racing, pull as much neg camber out as you can in order to get the tires to make full contact with the ground. It won't turn for sh*t this way but drag launches only using the inside of the tire are not conducive to quick ETs.