Bill Dearborn

Based on how the bulletin is written I got to wondering if they wanted at least one spacer between the UCA and the frame. Maybe GM knows the Z06 will always have one spacer and that is why they say not to remove it. They may also know the Z51 will always have at least two spacers so that is why one can be removed there. Need to have some car restoration buff who likes to study the production line do some research. Some of the guys I used to know when I was into car shows knew enough about the factory that they knew on what day certain bolts were introduced onto the line and how many cars should have the old bolt manufacturers markings and how many should have the new ones and on which side of the car they were located.

Bill

Mamandoli

They took all my washer out also to get the proper adjustments per manual and service manual.

Mad Dog 24

So am I reading into this we all could use a spy at GM on the Corvette assembly line,

Bill did you buy the same Acculevel gauge we use? It is a great tool we use all the time to get quick diagnosis without the need to set up all the other measuring equipment. Comes in a nice fancy case too!

Bill Dearborn

No spies but it is amazing how much info these guys develop about how the cars are built. When they say numbers matching they mean numbers matching right down to the imprints on bolt heads, date codes on hose clamps and what day any of these things changed during a production run. It is one of the reasons I moved to racing Vs showing car. I am not that **** about something in the grand scheme of things doesn't matter.

I purchased the LongAcre Digital Caster/camber setup in 2014 and used it to set the alignment on my C6Z. I thought it would work on the new car but the wheels won't allow the magnetic head to pass through and seat on the hub. Since I have the ceramic brakes I can't attach it to a rotor but I can hold it there to get a reading. It is a nice tool and with the bracket will work well measuring the rear caster (even directly measuring front caster if we clear all the brake scoops out of the way). The only issue with my bifocals, old eyes and insufficient light under the car it is hard for me to see those two small arrows indicating which direction the tool is leaning.

I don't know if you heard the old saying that you can get in touch with anybody in the world by contacting just 5 people but I tried to start that process today. You call somebody you know, they call somebody they know who calls somebody they know, who calls somebody they know, who puts you in touch with the person you want to talk to.

Bill

Mad Dog 24

Next Tuesday morning we have a top Hunter alignment tech and my guy ear marked to spend what ever time it takes to figure these C7s out. We discussed it at length today the issues and specifically the rear caster vs. toe under travel. Have some ideas that may or may not work for checking rear caster on most machines without any tools!

Wish there was a lift to use at the Glen to perform some at the track changes like toe. I'll report back if anything different comes out other than what's been beat to death here.

Bill I to have car show burn out. We use to follow the Goodguys shows all over with our street legal NASCARS. Could care less about the correct hose clamp, yuck! Could be age but OMG! Much more fun beating the sheetz out of them

tracer3030

I couldn't get the right rear to toe in enough so I modified the toe cam by welding the high side to push out more in the slot making it toe in. Left side adjusted toe

schaibaa

I'm thinking the car might run better with a touch less rear camber, say 1.4-ish. Corvettes aren't really sweeper cars - more about rotating the car and getting back to power. 1.4 might allow me to get power down a touch sooner.

BEZ06

I've heard of a couple of owners that have had a hard time adjusting toe to what they need.

I think that rather strange toe adjustment using an eccentric just doesn't give enough range.

Baer had an adjustable toe link (with a tie rod type of adjustment) at SEMA last year, but apparently didn't follow through with production. Below is a picture of what they said they were going to build:




I remember seeing a post from LGMotorsports that they were going to make a tie rod type link for adjusting toe. I recently PM'd Anthony at LGM and he said THEY ARE GOING TO MAKE ONE!!

He said that with the cooling issues and other things going on that the tie rod toe link had been sidelined, but they do intend to get back to work on it.

I think the tie rod link would be able to give a lot more range of adjustment, and it would be MUCH easier to fine tune toe adjustments. I haven't tried adjusting toe with the eccentric bolts yet, but it just looks like it will be much more difficult to fine tune than a tie rod type of link.

tracer3030

This was the before alignment from the factory. My rear tires are worn more to the outside so that's why I went to 2 degrees. In 2 weeks I'm going to Road America 2 day run so I will see if the camber is ok. Still thinking on this caster deal not sure I understand the effect it has on the car. I do think it should be even. I would like to bump it and see what's really going on

RapidC84B

Most of us who race Corvettes were surprised to see an eccentric for the rear toe. Odd they moved to that.

BaylorCorvette

Bill I know you've already ready this this you've responded to it. However I'm not sure if what I experienced was poor rear tires or possibly a bad rear caster set up. I have a thread going on here:

https://www.corvetteforum.com/forums...-on-track.html

To save everyone else the time going through that thread, the short story is I was at Texas World Speedway two weeks ago and the entire weekend the back end of my C7 Z51 felt extremely loose. I really had to be careful how I put on the power mid corner and corner exit. I had the dealer do a track alignment before this particular event but didn't have the rear caster checked. The other possibility on my end is the fact that the rear tires had seen several more track events than the fronts. Perhaps it is a combination of the two. Either way I've got new tires and will be getting the rear caster checked.

BaylorCorvette

Quick question, about what people are setting their rear caster to. It seems there is some inconsistency about if it is -0.8* OR +0.8* I've seen both stated on various threads on this forum. I know you're basically pushing it back towards the back of the car.

jim2092

While I have you all here. lol On a slightly different topic. When having my local Chev. dealer attempting to set rear camber on my 2016 ZO6 to -0.5 to save my tires as I do not race, their tech said he could only get to -0.6/-0.8 (from -1.2) before he could no longer keep the toe within factory specs. Sound right? He had been resistant to set to -0.5 on a previous occasion.

Bill Dearborn

That could make sense since others are having issues getting rear toe set when they go to -2. Service preferred setting is -1.1 with a +/- .6t tolerance. That gives a range from -.5 to -1.7. If the mechanic uses the cams to make the adjustment the bottoms of the tires are pushed in and if the adjustment range of the cam on the rear tie rod is limited you could see a situation where you could get too much toe in when going to a lower negative setting. He may have to add a spacer behind the UCA to get the settings you are looking for. The spacer should reduce negative camber by about a half a degree by pushing the upper part of the wheel out. That might provide a little more adjustment range for the rear tie rod cam.


Bill

Mad Dog 24

Jim that may be true although and without my specs in front of me our street set up in the rear was 0 toe with about -.5 camber or less. With the cams you are limited unless you start welding and grinding as Tracer did. This in my opinion is excellent no worry numbers.

Baylorcamaro, I'm thinking +.8 in the rear would be positive rear caster when the upper rear control arm is leaning back away from cars center and beyond the lower ball joint. Bill will confirm this or correct it hopefully.

Bill Dearborn

I think that is correct. Same as in the front. To get positive caster the upper ball joint has to be further to the rear than the lower ball joint. .8 is a pretty small number for caster. Although GM doesn't specify cross caster with their specs they basically limit it to 1.6 deg max in the individual specs at each wheel.

Bill

Kevova

For what it's worth GM announced a US dealer Loan Tool Program (LTP) April 5 2016. The purpose is to provide dealers with seldom used high dollar tools. Dealer does have to subscribe to program. Tool(s) would be express delivered to dealer and he would have 5 day to return them. So if several owners want to get alignments at a subscribing dealer; tools could be sent and all cars aligned one after another. GM Rear Caster tool and adapter is about 1100.00

Bill Dearborn

The rear caster gauge adapter is less than $200 and there are several lower cost gauges available that would let dealers do the measuring for less than $450.

The big problem now seems to be the adapter is out of production and nobody seems to know when they will be available. It definitely is not in the essential tools kit.

Bill

Kevova

on Ebay today CH-47960 digital angle gauge 180.00 no bids yet ends this afternoon. CH-47960-10 adapter showing to be available after 5/16/2016 you may need help from GM dealer to get it.

Mad Dog 24

We spent 4 to 5 hours on the track alignment of our Z06 a few days ago. After much adjusting and testing on the lift we found as you increase rear caster the toe in becomes more progressive during suspension compression. This is all if you have the camber in the -2.0 range which we have and by the way there is more to get there.

For testing purposes this coming weekend at the Glen we set the Left rear at +1.0 and the Right rear at +2.5 rear caster. So as I said the right rear will increase toe in on left cornering faster than on rights. We will soon find out if there is a seat of the pants feel or not. We set a bit of toe out in the front this time too.

To bad about that bracket no being available. I bet there are a lot of cars out of spec on rear caster. With that said those driven on the street will feel no effect other than an occasional wiggle in the rear.

Got our harnesses installed in a new way I will post some pics on another thread.