Limited Slip Rear End, Mismatched Tire OD

PITBoat

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I put some 16" Tahoe SS wheels on my 5-lug Suburban a while back, with LT tires that are a little taller than anything else I've got (so my spare'll be a different size).

I don't think that's a problem (having to run the spare for a while if I'm on a trip), but just wanted to throw that out for comment.

I know the wheels are going at different speeds when you turn, and I had a Firebird with limited slip that came with a donut spare that was prob a diff diameter, I just don't want to burn anything up inside there by spinning the rears at 2 different speeds for an extended time, or at hwy speed.
 

alldodge

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More heat will be generated because its a clutch that will slip more, but not like it does when turning. Having a 2WD and if it is the rear tire that gets the spare. At earliest conveniences I would move spare to the front
 

achris

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Different size tyres on an LSD will cook the (internal) clutches very quickly. Now a good idea. As a spare to get you a few kilometres to a tyre shop, yes ok, but for extended distances, and at highway speeds... Nah, if you do that, budget for a new diff.

Chris............
 

PITBoat

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Ok, I'm glad I asked that. I guess I need to get another wheel and tire like my set and carry that as a spare. Ty.
 

Scott Danforth

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If you have a G80 RPO code, your truck uses an eaton limited slip. No clutches, uses fly weights and requires a 120 RPM differential between the RH and LH axles.

you could run a tire with a 6" difference in diameter and never trigger the G80

So before you get worried, what RPO code diff?
 

matt167

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The G80 is technically a locker. But any GM truck will have the G80 IF it has any type of posi. Not sure about very recent GM's.. And agree it won't matter unless you try to do a smoke show. It will explode with the differential..

The Firebird would possibly have a Ford traction lock possibly, depending on what year it was
 

PITBoat

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Yeah I was wondering if there was some kind of threshold that needed to be met before that feature engaged.

Firebird was/is a '98. I can't swear the donut was a different diameter but I'm pretty sure it was, so that also argues that it's ok to do it for a while. Although the limitation on the tire prob. says 45mph...

I'll check the codes when the wife gets home with it. It's actually her vehicle. I just get to use it for the boat now and again.
 

PITBoat

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Both FB and Suburb have G80. FB is GU5 (3.23) and Suburb is GT4 (3.73). I've probably got VIN sheets on both of them somewhere.

I made the mistake of selling the 'bird to my son a few years ago and he wrecked it after about a year. I think he was hard on the rearend in turning acceleration, but I got it out a couple weeks ago (I'm "storing" if for him, and it's still driveable) and made a few straight line passes with it just into 2nd gear, and man, that thing still has it. Absolute rocket; at least compared to everything else I drive. Rearend worked fine too, both sides engaged during the hard accel. I changed the fluid a couple of times when it was mine.
 

Scott Danforth

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With the G80, your fine running a mis-matched set of tires.

If youre ever on ice and get one wheel spinning, you will know when the G80 lock engages. I have blown up 3 so far with a heavy foot while driving on ice
 
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