Alignment questions, limited adjustment range?

[Duc Hunter]

So after trying my car higher in March I went back down. Not as far down as I was, but close. My alignment numbers and lack of adjustability have me a little baffled though.

When it was high it was 26.75” front and 26.5” rear. The colored boxes you see below are the results of the alignment that was done after lifting it. We could not get the camber to change at all in front. In the rear it would get to -2.4 and then jump to -3 or more. So even that height the min camber was -2.4. This seems very strange, as the higher you go I thought the less camber you have, yet I cannot get close to factory spec’s (-.5) even that high. Conclusions from this alignment were that I needed to clear off the factory tar from the top of the shock towers (in the frunk), as that was preventing any movement on camber up front, and that maybe the eccentric adjusters were mangled in back, limiting my adjustability in back.

I decided to lower the car back down, fix the above issues and get another alignment. So I cleaned up the tar, installed new camber and tow adjusters in the back, and dropped it down. The car now sits at 25” front, 24.5” rear, and has a 1 degree nose down stance. The hand written numbers below are the results after the alignment, post lowering that car. Up front I cannot get any less camber, but -1.2 is not too bad. I had to use my strut brace to push the strut tops out to get to this figure though. Should I be able ot get less at this ride height up front?

The rear is the real concern. In this alignment the rear camber would go from -3.5, and jump to -3.9. Seems strange we could not get lower than -3.5, and seems strange there is only about .4 degrees of adjustment. Also the rear tow we could only get the left to .32, while the right was down at .19 before adjusting it, so we adjusted the right side to match the left. Seems like a lot of rear tow-in, though it is BARELY within spec.

Thoughts? Should their be more camber adjustability in back? What else could be wrong in back that even jacked up the camber is MUCH lower than stock?

The car has 935 rear spring plates, and is on coil overs. I was able ot speak to Clint at RSR (whose spring-plates I am using) and even he was baffled why at such a high ride height there was so much camber? I also notice that where the spring plate mounts to the Banian arm the arm seems to be as far back in the oval holes on the spring plate as it can go (see pictures below)

Passenger side all the way back, see the gaps in front of the spring-plate/banana-arm mount?


Drivers side, see the spring plate appears to be in the middle of its adjustment range? No gap on either side of the mounting bolts?

[Mahler9th]

I am not familiar with the Rebel Racing parts. I have the ERP version (Eisenlohr Racing Products). I think one design difference is that Cary's parts only have one slotted hole.

I do my own alignments and have helped many friends. I do not use a lift.

Are you turning your own wrenches? If so have you fully studied the possibilities/ranges one can achieve?

I have not spent the time to figure out the ride height versus camber curve for 911 trailing arms. What I have done is learned how to manipulate the parts carefully to get what I want... working them through ranges/arcs in various ways. Watching things move.

I have never used the toe eccentrics for adjustment. Even when I used conventional spring plates. Once I get what I want, I cinch the plates to the trailing arms so that the camber eccentric cannot move.. In some other thread or threads on here I posted some pics of how that can be done.


I cannot relate to fender heights-- I use the factory-style method.

Back years ago, I ran bias ply slicks. With SC trailing arms and spring plates. Pretty low ride height. After a few years running about -1 to -1.3 degrees of rear camber, our well-informed and experienced "herd" decided that about -0.75 to -0.8 was a more ideal choice for lap time versus wear. Try as I might, I could not manipulate my parts to get the camber in that range at the ride height I wanted.

My friend-- an expert who raced as a pro, told me exactly what to do. Have the spring plate slot welded up. Make a new slot exactly 10 mm lower. So I did just that. Pete Weber (Quiet Horsepower) welded them up. Then I made new slots with a die grinder.

Bolted everything back together, and viola, I had a new range to work with and was easily able to get the -0.8 I desired at my desired (quite low) ride height.

Those modified spring plates are for sale in the classifieds if anyone wants them. They can help you get a more favorable (less negative) range for a really low car (again in my case for bias ply tires that did not want so much camber), or a more favorable range (more negative) on a car with a higher height. They do not have rubber bushings.

Many ways to skin a cat.

If you'd like to discuss offline and are turning your own wrenches, and you think I can help, please feel free to send me a PM.

[Duc Hunter]

Mike,

I am mostly turning my own wrenches yes. In the case of this alignment I go to a good local alignment ship that has a nice Hunter. I tell them what wrenches to turn to get thw settings I want. Since it is a street car I am trying too get closer to stock than many out here like to run. I will ping you with a PM.

The really interesting part to me is that I had way too much camber when the car was jacked up, which was very strange. The car went more negative when I lowered it, a normal behavior I think for these cars.

[Stimorolgum]

Hello

Just had an alignment of my -73 and the same negative camber of the front strut.
Even with the factory tar removed and at the maximum mechanical stop.

I was reading that this is normal due to sagging of the strut towers, but should be OK anyway.

The caster was also out of spec but equal on both sides.


Cheers ��

[Duc Hunter]

One of the local mechanics I work with, and who is a ex-Brumos race & street mechanic, said back in the day they use to often take a "porto-power) to fix just that. He said they would put it between the shock towers in the strut and use it to spread the towers back out. He does not have one now unfortunately.

Something like this.

How was your rear? Are you lowered? The rear is more of a concern for me than the front.

CB

Originally Posted by Stimorolgum

Hello

Just had an alignment of my -73 and the same negative camber of the front strut.
Even with the factory tar removed and at the maximum mechanical stop.

I was reading that this is normal due to sagging of the strut towers, but should be OK anyway.

The caster was also out of spec but equal on both sides.


Cheers ��

[Mahler9th]

In my experience, there is nothing like getting having the car up on jackstands and manipulation the rear suspension to visualize how things move and the range of adjustment. Seeing it for yourself.

When I do a new set up with the 935 style plates, I set everything more positive than my target, and then dial in my desired number. Most folks here know that the standard arrangement has a design where camber, toe and ride height can change whilst you are manipulating the parts. With the 935 style-plates, you get to adjust toe somewhat separately, but it is not a panacea. It can all be a huge pain, and in my experience you can develop approaches and tricks over time.

It can take many hours to bring in a 911 rear. Sometimes shops won't take the time, because many customers won't pay. I have seen even skilled techs at famous shops take as long as 4-6 hours to bring one in.

I am not sure why one would need to spread the shock towers if the car has not been in a wreck and the parts are stock. I would think one should be able to achieve a range of desirable settings, including the factory numbers.

[Mahler9th]

For some applications, including mine, it may be desirable to take extra steps to prevent the rear camber eccentrics from getting loose.

A friend taught me a trick for this many years ago. And as a side benefit of this approach, I can manipulate the parts for a broader range of camber adjustment.

This thread may provide some illunitation:

Rear camber bolts

[eastbay]

First thing I would do if you want more stockish numbers is to verify that the spring plate lengths and adjustment holes are the same as stock. Can't quite see from the photos what is going on with the jam nuts at the front of the plates. Also, is the front pivot point in the same place as stock?

No idea, but I would guess Rebel would modify pivots, lengths, etc. to get max negative camber. Why else install them?

One other thought, when I started doing my own alignments I had issues with sticky slip plates giving false readings. If you do an alignment and the run around the block and recheck the numbers and they are different, then you know you have binding on the slip plates.

[Mahler9th]

Having installed a set of ERP's several years ago on my car, my hypothesis would be that Cary's design, and likely Clint's as well as others, would be very close to the factory parts in dimensions.

Understanding what the plates are meant for helps me feel fairly confident about that... I suppose one could ping Clint and/or CLE to find out.

Here is a DWG/instruction created by SRP/JWE for the ERP parts:




In my experience it takes some patience and focus to really study the way these parts go together and play around with how to get the range you want.

Having said that, it seems that one of the outcomes reported here is that the rear camber did not continuously move through a range... that the tech reported that to the OP. If I am reading that correctly, I have trouble understanding how that could be so (the result, not the tech's report).

911 rear alignment can be very iterative.

I remember one pro contributor to these forums once mentioned that he "has methods" to manipulate and adjust things. I too have methods. I suspect that his and mine overlap. I have probably about 100 hours of experience with this. He no doubt has several times more.

[Mahler9th]

Again, for anyone learning about this, I suggest car up on jack stands, wheel off. Manipulate the parts and observe/study how it all works together. Then develop an approach.

[rsscotty]

I had a strong suspicion I have been down this road before, doing setups and alignments for many years on these cars, so I ran the info by Jeff (Rothsport Racing) and he agreed with my thoughts and questions to him regarding your alignment. Call him and explain the situation , and this is regarding your rear spring plates specifically, and he will guide you down the proper path to fixing it. He knows his suspension setups and can get you the right parts. 503 822 5061 PDT Sherwood, Oregon

[Duc Hunter]

Originally Posted by rsscotty

I had a strong suspicion I have been down this road before, doing setups and alignments for many years on these cars, so I ran the info by Jeff (Rothsport Racing) and he agreed with my thoughts and questions to him regarding your alignment. Call him and explain the situation , and this is regarding your rear spring plates specifically, and he will guide you down the proper path to fixing it. He knows his suspension setups and can get you the right parts. 503 822 5061 PDT Sherwood, Oregon

Ironic you talked to Jeff. I have a call into him, and need to catch up. Good call.

Mike and I are trading emails too.

[Mahler9th]

Thanks to rsscotty and Jeff. And of course to Clint at Rebel Racing Products for trying to support his customer.

Please be aware that I am ready to help if I can, and of course let us know the outcome.

We are all in this together.

[Duc Hunter]

Well after talking to several people like Jeff at Rothsport, and including emails with Mahler9th, I bought a set of the Eisenlohr spring plates. They helped my situation for sure, but they did not "fix" it. My rear camber came down from a min of -3.5 to a min of -2.4. The drivers side will only get to -2.4, the passenger will go lower, which is little strange. My rear toe is -.16 each side now, my front caster is now -1.5 on ten drives and 0 on the passenger.

It peers that with my low stance, -2.4 is the best I can do. At one point we had the rear jacked up a little (to adjust the camber) and we have 0 rear camber with about 1" of gap between the tire and the fender.