Relationship between Toe and Camber - Rear Alignment Question

WideRide 86 · 05-09-2013, 07:44 AM

Good morning fellow Pelicans,

I'm hoping someone out there can shed some light on the finer points of rear alignment. Specifically, I would like to understand the relationship between rear toe and camber adjustments. I've reviewed Bentley and searched the interwebs and what I gather is that changing the camber will affect the toe setting and vice versa.

According to the Pelican Tech Article on alignment, after setting the camber adjustment to maximum...
" To set the toe back in, pull the wheel forward a bit with the forward eccentric bolt to get the same toe measurement as before."

I'm curious because I have more toe out than spec but its already adjusted to the max position. I also have more neg camber than I need. So I am wondering if I reduce the camber if I could possibly recover some toe adjustment. Any other tricks for recovering negative toe?

Thanks in advance for your insight!

cashman · 05-09-2013, 08:16 AM

I am far from an expert but just went down the road of using the level/string alignment to do the rear myself for the first time. I ended up with -2.5 on each side and -.040 toe on each side (-.080 combined) measured on 16" Rims.

My observations: Increasing negative camber created a toe out situation so I had to pull the toe back in. So I would assume going more positive on camber your adjustment will give you a little more toe in.

Why have you run out of adjustment? Are the bolts too close to each other to turn the toe eccentric? I ran into the same issue and had to turn my camber screw 180 degrees (either that or I assembled them wrong after using Cambermax adjusters).

WideRide 86 · 05-09-2013, 09:26 AM

Thanks cashman. Honestly, I'm going on information provided by a well respected local performance alignment shop. Although they are not a pcar specialty shop, they were recommended by some porsche folks here and they have a former factory mech on staff. Anyway, they checked the alignment and noted the toe and camber variance but said that the toe adjustment was already limited. After doing some research, I was thinking about attempting to reduce the camber and improve the toe myself.

So now, I'm trying to understand the adjustments, before I get in there and make things worse.

want I understand now is that the toe adjustment is limited by a slot. So if the adjustment bolt is already at the end of the slot, there is no further adjustment possible. Make sense?

cashman · 05-09-2013, 10:13 AM

Makes some sense. You'll learn a lot if you do it yourself and you can see how the two adjustments work together. If you screw it up too bad you can take it back for re-alignment. Others will chime in with much more knowledge than I. Be patient.

The eccentrics are oblong/Egg shaped and off center. Pulling them out and turning them 180 degrees may give more adjustment? Just a thought. My situation was when I originally re-installed my camber eccentric bolt the two bolts ended up too close to each other for washer clearance. Good luck. If you do it yourself it is very tedious but you will learn a lot. Give yourself a couple days to figure it out.

WideRide 86 · 05-09-2013, 07:39 PM

That is great advice. I hope to find some time get in to it next week. You are right, I think as soon as I start playing with it, it should start to make more sense.

Mahler9th · 05-10-2013, 08:36 AM

WideRide 86:

I also live in Norcal and have a lot of experience with aligning the rear of a 911 at home. I also have a lot of friends with shops that have experience. So ping me via PM if I can help you.

Note that depending on variables, there is some adjustability at the rear end of the spring plates... where the connect to the trailing arms.

On my race car, with my ride height and desired settings, I had to make modifications to my spring plates to get the numbers I need. For a street car, this shouldn't be necessary for most folks. But you can make slight mods to the plates if you need to. If you look at the Eisenlohr plates you will not that one or both of those rear spring plate holes are slotted. That is a hint.

One of the other things I have learned is a way of locking everything in place once I am done so the settings won't change. Somewhere on these Forums I posted a picture of this approach.

WideRide 86 · 05-10-2013, 03:06 PM

Thank you for the offer Mike! I may ping you after I take a better look for more advice or at least to get pointed to a god shop to help out.

Looking at the Eisenlohr plates helps a lot. I'm looking forward to giving this a try on my own.
cheers
~Doug

Mahler9th · 05-10-2013, 09:22 PM

You are welcome.

With factory parts on a street car you should be able to get decent negative camber settings with appropriate toe in at a preferred ride height.

I have an excellent custom made toe measurement tool that works with 16 inch wheels. The final method I use is with a set up very similar to the Watkins Smart Strings tool, invented right here in NorCal. My version is made with 1 inch electrical conduit and fishing line.

I can recommend a shop if you cannot get things sorted on your own. My recommendation will depend on where you live.

JP911 · JP911's Garage

Also a norcal neighbor and a (self-proclaimed) home 911 alignment expert. In my experience, if you back off camber towards positive, you will be able to adjust for more toe in (the opposite is also true). Pay head to Mike's recommendation to check out his method for locking things in place. If you do not put gorilla torque on the two bolts at the end of the spring plates, you run the risk of having your alignment settings slip. This is more likely on a race car, but no reason to not lock it down good and tight for a street car.

cashman · 05-11-2013, 06:32 AM

How much torque are you talking? More than Bentley recommends? I think it was in the 86-88 ftlb range.

Quote:

Originally Posted by JP911

Also a norcal neighbor and a (self-proclaimed) home 911 alignment expert. In my experience, if you back off camber towards positive, you will be able to adjust for more toe in (the opposite is also true). Pay head to Mike's recommendation to check out his method for locking things in place. If you do not put gorilla torque on the two bolts at the end of the spring plates, you run the risk of having your alignment settings slip. This is more likely on a race car, but no reason to not lock it down good and tight for a street car.

SiberianDVM · SiberianDVM's Garage

Interested in the amount of torque required as well, as I lost my neg camber on my L rear wheel last time I was at the track, making for some very loose turns.

I just added Elephants Rear Camber Max adjusters; this made adjusting the rear camber and toe a lot easier.

JP911 · JP911's Garage

The torque spec is great, except that there's almost no possible way of getting a torque wrench in there. I use a pair of long-handled 19mm box wrenches, with two pairs of hands cranking away on them. Another tip is to replace the hardware: bolts, large washers, schnorr washers, and nuts.

Mahler9th · 05-11-2013, 08:33 AM

Check out this thread:

Rear camber bolts

WideRide 86 · 05-15-2013, 07:24 PM

Thank you all for the further insight. The knowledge base on this board never ceases to amaze me.

Apologize for the delayed replies, I was out of town on the weekend and then battling the bug for the past few days.

From your responses and additional research, I'm starting to get a better understanding of what is going on. I stopped back in the shop this morning to flip flop my tires on the rims, and got more info on what was "maxed out" in the adjustments. Seems like I need to verify that the oblongs are installed in the correct position (off by 180*?).

My plan now is to measure and and document my current alignment at home, then start loosening things up and seeing what I can do myself. So for now I need to search and study the home alignment threads. I hope to be able to make some progress in the next couple of weeks. This seems to currently be my biggest challenge - getting time to work on her!

WideRide 86 · 05-15-2013, 07:28 PM

Quote:

Originally Posted by Mahler9th

I have an excellent custom made toe measurement tool that works with 16 inch wheels. The final method I use is with a set up very similar to the Watkins Smart Strings tool, invented right here in NorCal. My version is made with 1 inch electrical conduit and fishing line.

Mahler9th, would you be willing to share the construction of your toe measurement device? If its in the archives, I should be able to find it with the right key words.

Cheers!

Mahler9th · 05-16-2013, 09:13 AM

Sure. I have two set ups. One is a tool I bought from Roger and Brandon Kraus in Castro Valley (Roger Kraus Tires). I have known them for a long time and they have vast experience with set up of all kinds of cars, including Porsches. They get my recommendation for alignment and competition tires here in the SF Bay area. I worked with Brandon many times aligning my previous track car, often just verifying my work at home on his extremely well-maintained alignment rack.

The tool I bought from the Kraus' is designed to measure total toe on 16 inch wheels only. I will try to take some pictures of it and post them later.

I also have a set up made two pieces of inexpensive 1 inch dia electrical conduit. I use these with jackstands and fishing line. The method is age-old as documented in the Puhn book and by my old PCA acquaintance Ray Scruggs. And the instructions that Craig Watkins, et al, wrote for his SmartStrings product are great too. Craig has updated the SmartRacing Products web site indicating that this product is still available.

For this set up, I also made brackets to attach the conduit to my car in the correct position... a la SmartStrings and what they do in professional circles. This eliminates the need for jackstands.