anyone ever heard of this happening?

[TICK]

HI. been away from forum for a while. but not away from working on my 89 Z71, off road, and my 98 K2500 cheyenne. this is in regards to my 89, my tranny went out. the 3-4 shift. 700r4. was gonna rebuild, but a friend said i could have the tranny out of a parts truck he had. well it worked good, had a firm shift kit in it. just about bump your head off back window. all was fine, for about a year. then suddenly felt this bumping comming from rear, only under throttle, cost it would stop. i put it on the lift. ended up removing diff. cover, the carrier had a bunch of cracks running through it. the bumping was it was contacting the end of pinion gear. i believe that hard shifting tranny was to blame.

 

[Schurkey]

The 8.5" ring gear rear axle should never have been put in a full-size truck. It was designed in the late-60's and used in the early '70s in COMPACT and INTERMEDIATE cars. Full-size cars didn't get the 8.5 until engine power was dramatically reduced, and the full-size cars had been downsized into what had been "intermediate" size and weight.

The 8.5" axle assembly did get an upgrade in '88--'89, the axle shafts were made larger, which required different spider gears. Wasn't enough.

In addition, the 8.5" axle as used on GMT-400 pickups also got crappy leading/trailing shoe rear brakes of a mere 10" (254 mm?) diameter. The best thing you can do for your truck is to find a K2500 with 6-lug axles and the same gear ratio as what you have now, and swap the 9.5 axle in place of the crappy 8.5. The 9.5 axle is MUCH stronger, and has real (11.x, Duo-Servo) rear brakes as a wonderful bonus.

You'll need new U-bolts and a conversion U-joint on the rear of the driveshaft. The driveshaft will poke into the transmission about 3/4 of an inch more.

I did this years ago. Great upgrade!

 

[Supercharged111]

Check to see that all of your spider/side gears still exist. I shredded a spider gear eons ago which took out a few teeth on the R&P and that was without a shift kit. The truck let me know exactly when it happened. Like Schurkey said, that 8.5" diff can suck it.

 

[Erik the Awful]

The 10-bolt was fine for the time. We're spoiled by the horsepower wars that followed. 99% of the trucks made it to the junkyard without rear axle problems. Does it suck that you need to replace your entire rear axle for towing or anything performance related? Yup. Remember, vehicles aren't built for us enthusiasts, they're built to make a profit from the 90% of buyers who treat them like appliances.

 

[someotherguy]

The 10-bolt was fine for the time. We're spoiled by the horsepower wars that followed. 99% of the trucks made it to the junkyard without rear axle problems. Does it suck that you need to replace your entire rear axle for towing or anything performance related? Yup. Remember, vehicles aren't built for us enthusiasts, they're built to make a profit from the 90% of buyers who treat them like appliances.

Accurate. But yet, they still suck.

Richard

 

[MrPink]

I am awaiting the 600hp grenade that will be my 10 bolt, when that does happen I'll either go 9.5" SF 14bolt or build a 9"

 

[OutlawDrifter]

More than likely the abuse from your right foot....

 

[Jesse_Wenting]

I am awaiting the 600hp grenade that will be my 10 bolt, when that does happen I'll either go 9.5" SF 14bolt or build a 9"

How long have you been running this setup and how much do you abuse it? lmao

 

[MrPink]

I havent yet, but I will be once my Turbo LS is finished lol.

 

[Jesse_Wenting]

I havent yet, but I will be once my Turbo LS is finished lol.

Ah gotcha. Shouldn't take too long before you send that 10 bolt to the grave