1984 gmc truck rear diff issue

[lahoya77]

Am having a problem with the rear differential it is 8.5" 10 bolts.
Is there any chance to replace it with other truck differential wich is more reliable cuz am running vortec 5.3 and 700 trane so the rear diff is not handling the power that comes out.

Any advice please.

[nekkidhillbilly]

it should hold up to that.

[willett]

Shove a 14 bolt under there and never worry about it again.


I think a 3/4 ton axle will be a direct bolt-in and you can get disc brake conversions relatively inexpensivley if that's your flavor

[Cabnchassis]

Is that 700r4 stock? If so this would be the first time I've heard of power killing the diff before the 700 had a chance to poop the bed.

The gmt400 3/4 ton suburbans often have a single rear wheel 14 bolt ff. I don't know if the spring perches and shock mounts are right but that's the toughest stock single wheel axle you'll find. All the ones I've come across have 4.11 gears though so be ready to lose some hwy fuel economy especially if you're coming from 3.42s.

Some gm drivetrains have different yokes on the trans/shafts/diff so be sure check that the yoke on you're donor matches the yoke on your truck.

If it were me I'd see if the 14 bolt semi floater from a 2wd would bolt in, not as tough as a 14ff, but it's plenty strong for what you are after.


Beware a lot of these axles that you are looking at can come with the g80 rpo code(limited slip/posi setup) Most people call that g80 a time bomb cause now and then they get cranky and throw pieces through the pumpkin cover. I'll keep the one in my truck until it goes but I wouldn't put one in on purpose, but only because that setup add moving parts to the equation and I always lean toward simplicity. .

[lahoya77]

thank you all for the quick reply....I thing I will just get a replacing kit ..someone adviced me to go with this one :

http://www.ebay.com/itm/261225912250...ht_2013wt_1362

best regards

[Cabnchassis]

That looks like a full time posi unit. If you've never driven a posi-traction rear axle I'd suggest you do it before you swap one in. Posi has it's benefits but the trade offs are to be overlooked. You might want to research the difference between open, limited slip, and posi-traction diffs so you can see what you are gaining/losing here. If your truck is stock and you don't have the g80 rpo code then you have an open diff. If you have a g80 rpo code you have a limited slip/posi in there. Either one is a far step from the full time posi.

[lahoya77]

Originally Posted by Cabnchassis

That looks like a full time posi unit. If you've never driven a posi-traction rear axle I'd suggest you do it before you swap one in. Posi has it's benefits but the trade offs are to be overlooked. You might want to research the difference between open, limited slip, and posi-traction diffs so you can see what you are gaining/losing here. If your truck is stock and you don't have the g80 rpo code then you have an open diff. If you have a g80 rpo code you have a limited slip/posi in there. Either one is a far step from the full time posi.

Thank you so much

[Keith Seymore]

Originally Posted by nekkidhillbilly

it should hold up to that.

x2.

I still have the original 8.5" 10 bolt in my Chevelle. Racing for 36 years, 20 or more of those in the 11's or quicker. Currently just under 1000 hp and 3950 lbs (with me in it).

K

[lahoya77]

Originally Posted by Keith Seymore

x2.

I still have the original 8.5" 10 bolt in my Chevelle. Racing for 36 years, 20 or more of those in the 11's or quicker. Currently just under 1000 hp and 3950 lbs (with me in it).

K

Thank you will stick with mine but need to look for some parts to renew it again cuz the truck shakes at 60 mph the posi broken from the I inside.

[dman1982]

Originally Posted by lahoya77

thank you all for the quick reply....I thing I will just get a replacing kit ..someone adviced me to go with this one :

http://www.ebay.com/itm/261225912250...ht_2013wt_1362

best regards

thats the set up i went with on my k10...except 4.56 gears...you got a little better deal than i did, i didn't see the complete diff and gear set when i got mine...you saved about 100-150 doing so

[Ski-me]

You could drop in a 14sf axle up to a 91' old body style. It will bolt straight in, same perches and shock mount locations. The only problem is they are all 8 lug. You could switch over to 8 lug or some horse trading in a junkyard. You would need from a newer 6 lug, 14sf axle: axle shafts. Brake backing plate and brake drums. Fab a 1/2" spacer for backing plate (due to longer axleshafts)....and you're good!

[MikeB]

What are the symptoms? And have you pulled the cover?

I wouldn't go out and buy that complete kit unless I knew what the problem was. Could be something as simple as an axle bearing. Even if it's a pinion or carrier bearing, the R+P gears might be OK.

Regarding the kit, there are two types of Yukon R+P gearsets. The YG-series costs more but is quieter than the ZG-series.

On another note, an 8.5" 10-bolt will hold up to a lot more torque than a 5.3 will make, especially with an auto trans.