Checking Rotor Runout - How?
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Joined: Aug 1999
Posts: 15,097
Likes: 3,890
From: Connecticut, USA
Re: Checking Rotor Runout - How? (Langadorf)
You need a dial indicator, preferably one with 1" travel. You will also need a mount to attach it to the car frame. I use a magneatic indicator base and C clamp it on for stability. Most tool catalogs have these in the $30-$300 range.
Once you get it in place and the tip on the rotor, mark the rotor so you know when you've gone 360*. Preload the indicator a little bit by pressing it on the rotor and watching the smaller needle load. Now rotate the dial to zero,this is your start point. Slowly rotate the rotor by hand and watch the indicator needle through 360* add both the neg and pos side of zero for your total runout. Anything over .003 should be checked out. The rears are setup to .001-.002" I think the manual gives spec's up to .005" but that's a little too much for me.
Good luck the investment in the tools will pay for itself over the life of having a vette.
Gary
Once you get it in place and the tip on the rotor, mark the rotor so you know when you've gone 360*. Preload the indicator a little bit by pressing it on the rotor and watching the smaller needle load. Now rotate the dial to zero,this is your start point. Slowly rotate the rotor by hand and watch the indicator needle through 360* add both the neg and pos side of zero for your total runout. Anything over .003 should be checked out. The rears are setup to .001-.002" I think the manual gives spec's up to .005" but that's a little too much for me.
Good luck the investment in the tools will pay for itself over the life of having a vette.
Gary
Race Director
Joined: Nov 2000
Posts: 11,872
Likes: 12
From: Waterloo ontario Canada
Re: Checking Rotor Runout - How? (Langadorf)
You will find the back not easy to do. With the car on jack stands the rear wheels hang down making it impossible to smoothly turn the rear end over. The universals bind in the full hang down position so the wheels have to jump up every time the universal rotates.
The only way I know to do the back properly is to release the outer bolts on the spring, remove the 4 bolts on the outer flange for the half shaft, remove the caliper and install the 5 lug nuts. This allows smooth easy turn over of the rotor. If the wheel bearings are on the loose side even shimming the rotors might not get you in specs.
I start off with setting the wheel bearing clearances front and back to around .001, then shim the rotors for .003 max runout including wheel bearing clearances.
Setting the front bearings is not just tighten the nut then back off to the first cotter pin hole. This is wrong and sometimes it takes valve spring shims to set this clearance correctly.
You will have to make shims and pop cans are thin enough for this along with large hole punch.
Good luck but to do it properly is a lot of work.
The only way I know to do the back properly is to release the outer bolts on the spring, remove the 4 bolts on the outer flange for the half shaft, remove the caliper and install the 5 lug nuts. This allows smooth easy turn over of the rotor. If the wheel bearings are on the loose side even shimming the rotors might not get you in specs.
I start off with setting the wheel bearing clearances front and back to around .001, then shim the rotors for .003 max runout including wheel bearing clearances.
Setting the front bearings is not just tighten the nut then back off to the first cotter pin hole. This is wrong and sometimes it takes valve spring shims to set this clearance correctly.
You will have to make shims and pop cans are thin enough for this along with large hole punch.
Good luck but to do it properly is a lot of work.
