Rear Camber Alignment question?

[golfprowanabe]

I dropped the Cobra with H&R Race springs without isolators. There became an obvious negative camber problem in the rear with both tires. After taking it to a tire shop, I was told they couldn't even reach the bolts to make the adjustment. So I decided to take a look at it myself. I realize the only adjustment is with the bolt with an eccentric washer that attaches the upper part of the knuckle. By using a level on the rim, and trial and error, I got the driver side rear to sit up pretty straight with just a hint of negative. However on the passenger side, I have the biggest part of the lobe on the bolt pushing the knuckle out as far as it can (lobe on the inside pointing toward the diff), but it still doesn't look like it's enough. It's definately better, but the tire still looks like it's leaning in. Is there something else I can do, besides putting in isolators, that can bring the adjustment closer?

 

[frank5o]

Hows the rear compared to the front?
Make sure the car is on a level surface, and your air pressures are correct. You should have around 1 degree of negative camber on all four wheels, so they should all be about the same negative camber wise. Besides that, the only way to know for sure is to have an alignment done.
If you are maxed out, and still don't have enough camber, then you should bring the ride height up...

You are messing with the rear toe if your moving the rear camber around, so make sure you get an alignment done, your car is going to be all out of wack....

 

[racebronco2]

Most people have the opposite problem, not enough camber. The fix is the same. You will need to grind away at the eccentic part of the lobe or oblong the spindle a little more. The rear should have some negative camber to it. I would make sure the top edge of the rim is at least 1/4" inwards at the top compared to the lower part of the spindle.

 

[frank5o]

Most people have the opposite problem, not enough camber. The fix is the same. You will need to grind away at the eccentic part of the lobe or oblong the spindle a little more. The rear should have some negative camber to it. I would make sure the top edge of the rim is at least 1/4" inwards at the top compared to the lower part of the spindle.

By saying "not enough camber" you mean negative camber right?
If you grind away at the lobe or the knuckle you will increase negative camber..The op has to much negative camber already..

 

[mblgjr]

Eh...

I had to grind off part of my pass. side lobe.

On another note...the IRS geometry is "backwards" from what you would wish.

From ride height; droop/extension (raise body, allowing arms to droop) the tires will go Negative.

Under compression; they actually go positive.

I had actually queried Bruce about this and then went and checked myself and its true.

So when you LOWERED the vehicles ride height, you should be fighting to get enough static negative camber.

 

[golfprowanabe]

Well I might SHOULD of had to fight for negative camber, but I didn't! It's quite simple over here; the top of the tire is leaning in toward the center of the car and I don't have enough lobe on the washer to push the knuckle any further out. I wonder if grinding out some of the spindle would work?

Eh...

I had to grind off part of my pass. side lobe.

On another note...the IRS geometry is "backwards" from what you would wish.

From ride height; droop/extension (raise body, allowing arms to droop) the tires will go Negative.

Under compression; they actually go positive.

I had actually queried Bruce about this and then went and checked myself and its true.

So when you LOWERED the vehicles ride height, you should be fighting to get enough static negative camber.

 

[3Dglasses]

You might bring it by S&R performance since your in Tampa. They are great with alignments on lowered Stangs and have done a lot of suspension work for me and many others... Talk to Bobby or Mike about your setup. He knows his chit..

 

[racebronco2]

By saying "not enough camber" you mean negative camber right?
If you grind away at the lobe or the knuckle you will increase negative camber..The op has to much negative camber already..

You need to grind in the opposite direction for more positive camber, which would be on the lobe section furthest away from the car. More negative camber closest to the center of the car.

 

[ac427cobra]

Well I might SHOULD of had to fight for negative camber, but I didn't! It's quite simple over here; the top of the tire is leaning in toward the center of the car and I don't have enough lobe on the washer to push the knuckle any further out. I wonder if grinding out some of the spindle would work?

In some cases, the slot on the upper control arm restricts required travel. So what you're going to have to do is remove the tire, mark the location of the eccentric and disassemble to see if in fact, you could be assisted by the slotting the UCA more. Use a Dremel tool with carbide bit.

You will also notice that the washer on the head of the UCA attachment bolt is a smaller diameter than the slot width in the UCA so keep that in mind. Just so you know, you can't make these adjustments with the vehicle's weight on the tire.

Many times you can 'physically' pull the top of the tire out much further than the eccentric cam will adjust it. This can be done with a strap and a long 2x4". Strap the wheel at the top and pull the wheel outward with the bottom of the 2x4" pushing against the bottom of the wheel. (Us track guys have the opposite problem of not getting enough negative camber in the IRS and we try to push the top of the tire in) Don't worry, it won't move once it's tight. The majority of the pressure is on the LCA attachment point.

If you're checking the tire in a flat concrete surface you should be pretty good if you lay a carpenter's square on the floor up against the botton of the wheel and measure about a 3/16" - 1/4" gap on the top of the wheel. (less aggressive numbers for street only and more aggressive numbers for track)

FWIW

:thumbsup::coolman::beer:

 

[golfprowanabe]

I believe you're right about the slot in the UCA restricting the travel. When I loosen up the eccentric bolt and rotate to give the least neg. camber, I can see that the short side of that bolt does not touch the UCA at its edge, which would mean that the short side is not restricting the knuckle from coming out further. But when the bolt is loosened, I can easily move the knuckle back and forth and feel hard stops on both inward and outward movement. This leads me to believe that its at the end of the slot on the UCA.

In some cases, the slot on the upper control arm restricts required travel. So what you're going to have to do is remove the tire, mark the location of the eccentric and disassemble to see if in fact, you could be assisted by the slotting the UCA more. Use a Dremel tool with carbide bit.

You will also notice that the washer on the head of the UCA attachment bolt is a smaller diameter than the slot width in the UCA so keep that in mind. Just so you know, you can't make these adjustments with the vehicle's weight on the tire.

Many times you can 'physically' pull the top of the tire out much further than the eccentric cam will adjust it. This can be done with a strap and a long 2x4". Strap the wheel at the top and pull the wheel outward with the bottom of the 2x4" pushing against the bottom of the wheel. (Us track guys have the opposite problem of not getting enough negative camber in the IRS and we try to push the top of the tire in) Don't worry, it won't move once it's tight. The majority of the pressure is on the LCA attachment point.

If you're checking the tire in a flat concrete surface you should be pretty good if you lay a carpenter's square on the floor up against the botton of the wheel and measure about a 3/16" - 1/4" gap on the top of the wheel. (less aggressive numbers for street only and more aggressive numbers for track)

FWIW

:thumbsup::coolman::beer:

 

[ShelbyGuy]

In Ride it will gain negative camber as ride height decreases. In Roll it will gain negative camber on the outside and positive camber on the inside. Toe will also change, and can be tuned to allow a 'rear steer' effect in roll.

Eh...

I had to grind off part of my pass. side lobe.

On another note...the IRS geometry is "backwards" from what you would wish.

From ride height; droop/extension (raise body, allowing arms to droop) the tires will go Negative.

Under compression; they actually go positive.

I had actually queried Bruce about this and then went and checked myself and its true.

So when you LOWERED the vehicles ride height, you should be fighting to get enough static negative camber.