97c1500ext
Newbie
I'm well aware, that wasnt my question. Im looking for the weakest link. Is it the exact same axel or not? I want to know what part of the rear actually fails.Your truck weighs a thousand pounds more.
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I'm well aware, that wasnt my question. Im looking for the weakest link. Is it the exact same axel or not? I want to know what part of the rear actually fails.Your truck weighs a thousand pounds more.
Wheel hop is what is going to destory it. The heavier the vehicle and the more torque it makes the easier it is to break something when it wheel hops. My 8.5 actually overchrushed the pinon crush sleeve and then ate the ring and pinon because the gears were no longer in the correct mesh. A good build will use a crush sleeve eliminator to make certain the pinon gear stays where it belongs.I'm well aware, that wasnt my question. Im looking for the weakest link. Is it the exact same axel or not? I want to know what part of the rear actually fails.
Thank you, all of your responses have been greatly appreciatedWheel hop is what is going to destory it. The heavier the vehicle and the more torque it makes the easier it is to break something when it wheel hops. My 8.5 actually overchrushed the pinon crush sleeve and then ate the ring and pinon because the gears were no longer in the correct mesh. A good build will use a crush sleeve eliminator to make certain the pinon gear stays where it belongs.
The 8.5" is an improvement over the 8.2"; which was used beginning in the early-to-mid 1960s primarily behind small-blocks.Plenty of racers do 8.5 swaps over an 8.2, is it really as pathetic as people say?
Some 8.5s have bolt-in axle shafts. Most have C-clips. I won't make any promises on the actual differential cases, but I suspect they were changed--perhaps multiple times. Of course the Gov-Bomb case was never used in a Camaro or non-truck Chevy. The open case MIGHT be a carry-over from The Good Old Days, but I won't put money on it.Is there a difference between the 8.5 in these trucks and the 8.5 in camaros or other chevys?
Most of the problems with the 8.5" axle are differential case failures. Gov-Bomb differential cases of 8.5" and smaller are prone to shattering. The 9.5" and bigger seem fairly robust.i already have a newly rebuilt 8.5 with a trutrac in the truck. Its not a stock G80 grenade. I also intend on adding TA Girdle and potentially having the tubes welded.
I don't know how the crush sleeve can be over-crushed in service. The rear bearing cannot move on the pinion gear, it's seated against the pinion head, the race is seated against the housing. The front bearing outer race is seated against the axle housing. Neither one should be able to move tighter onto the crush sleeve unless one or both of the bearings fail first.My 8.5 actually overchrushed the pinon crush sleeve and then ate the ring and pinon because the gears were no longer in the correct mesh. A good build will use a crush sleeve eliminator to make certain the pinon gear stays where it belongs.
I do not pretend to know the whole sequence, but both bearings and the crush sleeve as well as the ring and pinon were trashed. When the ring gear was removed, the pinon had 1/4" of play front to back and the pinon nut had not backed off. Always just assume it was a crush sleeve failure that started it all. I found the 9.5 SF 14 bolt for $300. Far cheaper than rebuilding the trashed 8.5. IIRC it cost me $75 per axle to get the bolt pattern redrilled and new studs pressed in. On the Express/Savanna 9.5 housing atleast it used the same backing plates as the 8.5. I replaced the mangled, bent up ones on the wrecking yard 9.5 plates with the still like new ones from my 8.5. With the axle bolt pattern redrilled my stock drums went right on. The 7,100 and 7,300 lbs vans had the same rear drum setup minus 5 vs 6 lug drums. The front brakes were the same too, just different rotors for the wheel bolt pattern change.The 8.5" is an improvement over the 8.2"; which was used beginning in the early-to-mid 1960s primarily behind small-blocks.
The 8.5 was designed for compact and intermediate vehicles, mostly with small-block engines, not for full-size pickups. Far as I know, GM never put the 8.5 into a full-size car until '77 when "full size" cars were downsized to the intermediate platform. GM didn't put an 8.5 in with a "Big Block" engine until after the big-blocks were emasculated by emissions controls and low compression.
Some 8.5s have bolt-in axle shafts. Most have C-clips. I won't make any promises on the actual differential cases, but I suspect they were changed--perhaps multiple times. Of course the Gov-Bomb case was never used in a Camaro or non-truck Chevy. The open case MIGHT be a carry-over from The Good Old Days, but I won't put money on it.
Most of the problems with the 8.5" axle are differential case failures. Gov-Bomb differential cases of 8.5" and smaller are prone to shattering. The 9.5" and bigger seem fairly robust.
Even the "open" differential cases in the 8.5" are weak and will explode.
So adding an aftermarket differential case is probably the single-best thing you can do to improve reliability of an 8.5" axle. Welding tubes-IF DONE CORRECTLY--is another reasonable plan. Problem is, it's really easy to warp the axle housing. I'm not opposed to adding a "girdle", although I gotta say that it seems to me that girdles are an excellent way to lighten your wallet.
You'd be WAY better off to get decent rear brakes (11.x Duo-Servo drums, for example) than to dump a bunch of dough into welding tubes and installing a girdle. But that assumes you have the horrible 254mm Leading/Trailing drums now.
I don't know how the crush sleeve can be over-crushed in service. The rear bearing cannot move on the pinion gear, it's seated against the pinion head, the race is seated against the housing. The front bearing outer race is seated against the axle housing. Neither one should be able to move tighter onto the crush sleeve unless one or both of the bearings fail first.
But I have lots to learn about axles and gear-mesh, so maybe I'm wrong.
All I can tell is I know what started the failure and it was my size 11 right foot on the skinny pedal. Banging the WOT upshifts so hard with torque management disabled that it would break the right rear tire loose and wheel hop shifting into 2nd at 50 mph. Also wheel hop from spinning the right rear tire on a hard take-off with the open differential. The 4L85E has somehow managed to live through that abuse, knock on wood.I am thinking--perhaps I'm wrong--that the only real purpose of the crush sleeve is to give the pinion nut something to press against (via the front bearing inner race/rollers.) With the crush sleeve in place to press against, the pinion nut has some thread friction that keeps it from backing off. IF (big IF) you could lock the pinion nut so it couldn't turn on the pinion threads by itself, you wouldn't need a crush sleeve at all.
But like I said...I've been wrong before.
I'm moderately certain you had a bearing failure that damaged the crush-sleeve, not the other way around. Or--who knows--maybe the sequence started with metal chips between ring and pinion that applied excess side-thrust on the bearings. Hard to say.
I don't know how the crush sleeve can be over-crushed in service.