Carl Fausett

Background: Putting wider rear tires on your 928 is almost a right of passage. We all do it, and it looks great. The problem comes at the rear camber eccentric, where the OEM design pits a steel eccentric against an aluminum casting. The aluminum can't hold up, and the wide tires increase the force exerted on it many times over stock sized tires. If the owner is a performance driver or a racer and likes to hit the corners hard, the damage to the camber box happens even faster. The end result is more and more rear camber as the eccentric bites into the aluminum. This shows as uneven tire wear, wandering on lips in the pavement, and locking up the rear tires too easily on hard braking. Not to mention (and most importantly) oversteer!

Description: The 928 Motorsports Rear Camber Pocket is a steel insert that nests into your rear crossmember, lining the camber packet. Now you have a steel-on-steel alignment adjustment - your 928 can be restored to correct rear camber settings, and it will hold those camber settings.
Installation: Can be installed with the rear suspension on the car. Remove the two camber eccentric bolts, alter the crossmember to hold the steel pocket, and re-install the camber bolts. Modification of the aluminum camber pocket will require a die grinder or a Dremel tool or similar. Instructions are provided, and also available on line. Instructions also show how to pin the rear camber eccentric for racers (not needed for street-driven cars).

Details Here: http://www.928motorsports.com/parts/...er_pockets.php

Complete installation instructions here:
http://www.928motorsports.com/install.php

Carl Fausett

Typical on-car installation

Carl Fausett

If you really hit the corners hard with wide, sticky tires, you’ll find that the lateral force is great enough to turn the camber eccentrics in their pockets no matter ho hard you tighten the nut.

For example, I would go out at –2 deg negative rear camber, and in a couple laps be at –3.5 degrees camber.

The answer was to drill and pin the eccentric. Can be done on the car.

Gather up a M6 tap and the drill for it, and a small M6 fastener like the one shown below. A center-punch will also help. Set your rear camber they way you want it and tighten the nut on the other side as per the WSM. Mark the eccentric for drilling with the punch, and drill through the eccentric, the steel liner, and into the aluminum. Tap the hole. Insert your M6 fastener with some Loctite on the threads—done!

ammonman

Excellent idea. I've been dreading the day I need to replace my rear cross member to address this issue.

Mike

Mrmerlin

also note the torque spec for this bolt is 140 ft/lbs,
when they are moving it will be found they are usually loose,
as it takes a big wrench to get it close to tight

James Bailey

Correct the eccentric is for adjustment Not to carry the load. The torque of the bolt is supposed to hold it in position....same as the front lower a-arm caster camber eccentrics.

Tom in Austin

Ingenious idea. Would be nice if you could chamfer the bottom corners of the inserts to better fit the opening.

Now how to convince the mar-oons at the alignment shop to use a torque wrench and actually put 140 ft-lbs on those bolts?

"Oh yes sir, we'll make them good and tight" ...

Carl Fausett

Right to all. I put 140 lbs on that fastener, and like I said, with 315's on the rear, it spins in the pocket anyway. Not on my street car so much, but on the race car all the time. Pinning it fixed it.

Working on: I'm looking into making several sets of rear eccentric bolts with the eccentric moved over... I will take the OEM bolt and weld it up on one side and then have it ground to move the ellipse.
The idea: At best with wide tires, I can get about -2 or -2.5 deg rear camber. Still a little too much for optimum cornering. I think if I move the ellipse over I can get to -1.5 rear camber with the wide tires.

I actually did this a couple of years ago and it worked. But they were ugly. Now I want to make up a few sets and make them professionally.

Tom in Austin

Good alternative for street, adjusted eccentrics that compensate for wear in the pocket area

toofast928

Genius, I'll get mine in the winter. Too busy driving now.

Carl Fausett

Anybody with pics of hobed-out camber pockets on their rear crossmember, please post pics!

mark kibort

Carl, I've set my rear suspension 15 years ago to 2 degrees camber and its stayed that way, ever since . we are talking 15 years of full season racing!
never have i had to adjust any more camber out and its held over the past 15 years with no movement and great tire wear. Ill try and take a picture of these pockets to see if anything is worn, but as you know, I've run 335 rear tires for all these years as well, and much of the time, they are real slicks or at least A6 Hoosiers. So, im curious to know if this is a problem for others.

FredR

Mark,

I have a problem like this in that the adjustment bolt flange has punched into the guide shoulder. I suspect that the bolt was torqued incorrectly at some stage. I have to do something to correct the issue and this looks like a neat solution.

I also have another problem in that the minimum camber I can set is about 2 degrees on the driver side and that cannot be set unless the adjuster is pushed over manually as the adjuster is out of range because of the indentation in the shoulder. I am assuming this is caused by permanent sag in the dog bone bushes- doubtless our very hot climate not helping matters.

I find -2 degrees rear camber works well during hard cornering but I have some trouble getting off the line at the moment -perhaps I have a bit more camber than I set. Must do this mod and reset the camber/toe. I prefer to run with -1.5 degrees on the rear for day to day street driving.

Rgds

Fred

mark kibort

sounds like you have something really out of wack, if the min camber is only 2 degrees. this is not normal from what ive seen on a bunch of 928s early and late models.
if you are having launch issues, its probably not due to the camber, unless you have real soft springs and the compression brings the camber to about 3-4 degrees on launch. its one of the reasons you dont need that much camber in the rear, as under compression, the camber changes quite dramatically to handle body roll and keep the tire flat.. however, if too soft of a spring rate, it will work against you .

FredR

Rear springs Eibach- 25% stiffer than stock. Something is definitely wrong but it is more or less the same both sides. I set rear toe to mid range to give it some bite. I do run a bit on the low side - a few mm below the lower end of the spec range but not as low as you run. I would expect the min camber to be about zero.

This mod will get me to at least work the problem a bit but it will not solve my adjustable range issue. Nothing to suggest something is bent and no accident history. I have a spare pair of dog bones I can try- if that or a refurb does not fix it then I am out of ideas. All these joints with rubber bushes in them puts the ******* up me given the way heat tends to get to such.

Rgds

Fred