Hi Les and others,

That standoff and alignment tool (or any of the bubble level tools of a similar design) will work just fine on a level surface if the standoffs don't flex too much. If the coach is on a pad that is not level you need to find a way to establish level relative to the pad. With those standoffs you can also use an inexpensive cube digital angle finder instead of the more expensive bubble level contraption as it has an ability to zero to the pad built in and is more accurate than your eyeballs trying to read a bubble level.

The most important thing for a gmc is to get all six wheels frame parallel before you do anything else. While that can be done with strings and such, it is much easier to do with a laser and target that indexes to the frame. Simply fit a laser torpedo level so it will magnetically attach to the standoff on the same center surface where the bubble level attaches. Place your target (anything the laser can see that will reach under and touch the frame for reference) and note where the laser hits when the target is close to the wheel being checked and when the target is as far away from that wheel as you can get and still reference the frame. Adjust the wheel until the laser hits the target in the same place and that wheel will be frame parallel. When all six wheels are frame parallel then you can set camber caster and toe as you wish.

I found most Gmc's with radial ply tires will drive well with as much caster as you can get and be the same on both sides. For most stock Gmc front ends that will be around 2 degrees. With offset bushing on the rear of the upper A arms, around 3-4 degrees. With the one ton front end or modified upper control arms maybe a bit more but do not exceed 4-5 degrees or you risk over stressing the front end during low speed turns.

Front caster should be as close to zero as you can get and be the same on both sides. I also found zero toe to be good for most Gmc's. If your front end is a bit loose, some will recommend dialing in some toe to compensate for the tendency of the wheels to flair on a front wheel drive vehicle under acceleration.

On the rear four tires adjust to about 1 degree tire top in camber with the wheels frame parallel.

Reach those objectives and your gmc will drive one finger on the wheel. Center the steering box before you do the rest and it will drive even better. As Alex F. has shown there are a bunch of ways the sliding element, u joint and lower mount can go together and only one is correct to properly center the steering box. If you don't know how to do that, then put the two front wheels on plastic bags (to reduce the turning friction), turn the steering wheel all the way to one side, then count the turns required to turn all the way to the other side and turn the wheel back half that number of turns to find something approaching a centered steering box.

If your front end components are old, worn and loose all bets are off when it comes to alignment.

Jerry

Jerry Work
The Dovetail Joint
Fine furniture designed & hand crafted
in the 1907 former Masonic Temple building
in historic Kerby, OR
http://jerrywork.com
.........
Date: Sat, 7 Oct 2017 11:22:59 -0400
From: Les Burt
To: Gmclist
Subject: [GMCnet] Wheel alignment tools
Message-ID:
Content-Type: text/plain; charset=us-ascii

Some may find the following tools of interest now that Gerry Work is no-longer producing his alignment kit.

https://www.ecstuning.com/News/Schwaben_Professional_Magnetic_Camber_Caster_gauge_13159


Les Burt
Montreal
'75 Eleganza 26'
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