Ok, i bought a 69 elk, has a 12 blt casing on it, i was told when i bought it, that the guy before the guy i bought it from took posi gears out of casing and put in 10 blt gears axles ect,,
So i am feeling a shuttering as i gain speed, feels like rear end, not posative, just a feeling.
My question is,
Can you do this? and is it ok? are 10 blt gears compatable with 12 blt housing??
thanks ahead for help..
Alan.

Sounds to me that someone jerryrigged that rear together. As far as i know, you can't do that. I think you've got a time bomb on your hands. IMHO

Yea, im finding out that who ever,, did alot of jerryriggin on the elk.
Very frustrating indeed.
Thanks for info furball8994 :)
Any one else ??

It could be the Olds 10bolt. Has a 12bolt cover but a weaker 10bolt gear. Good thing is that the Olds is stronger then the Chev 10bolt, but weaker then the 12bolt.

Steve

i dunno, i just know what he told me, said it was a 12 blt posi in it, but some guy had taken out posi set up and replaced it with 10 blt inners, i verified 12 blts on it, but im pretty sure i am having issuse.
Thanks for responce:)

10 bolt parts will not fit in a 12 bolt housing. It can't be done. This could be the Olds rear end, like Steve said. It has 12 bolts in the cover, and many people mistake it for a 12 bolt. If it were mine I would be looking at the drive shaft first.

10 bolt parts will not fit in a 12 bolt housing. It can't be done. This could be the Olds rear end, like Steve said. It has 12 bolts in the cover, and many people mistake it for a 12 bolt. If it were mine I would be looking at the drive shaft first.

Thanks for responding..
So what am i looking for on driveline??
And did elk come with olds diff stock? or its just compatible?? thanks again:)

Heres my findings so far..
1st and 2nd go fine, for the most part.
when i hit 3rd, it begins to shutter, pop it back down to 2nd, its still shuttering, It will shutter around 30mph, but then it shutters under that once i get the body moving, now if i pop in neutral no shutter.
And in park, i match rpm as when im driving, no shutter,( i was thinking it was the eng)
ok, so rear end?? u joints seem fine, driveline is solid, could this be a tranny issue?
What can i do to test the trans and rear end?
Thanks,,
Alan.

Ok, new info on this,
I just got back from store, and i had my wife with me, and i really didnt feel shuttering, at all, so added weight made a big diffrence, cause before, when i would drive it, i was alone, and it did as i said before, now with added person,
(weight) its not there,
whats that all about?? lol, any ideas?
Alan :)

im at a loss here,, gonna take it some where tomorow to have front end checked out,
anyone have any ideas on this prob?
thanks
Alan

From what you have said, I'd start looking at the driveshaft and u-joints as BGH had said. Something seems either loose, worn and just out of balance.

Have you popped the rear diff cover off yet and counted ring gear bolts? What about an axle code from it? Either of those will tell you for sure what the rear end is.

But from the way you are describing the shuddering only when it's under load and moving at certain speeds leads me to believe a balancing problem somewhere and worn parts.

Have you checked the brakes and all since you bought it?

Good Luck,
Bill C.

Thanks Bill for responce.
I have checked brakes and all is well in there.
I know the E brake cable was rubbing driveline, but i fixed that prob, doesnt look like there was a weight at that point of rubbing, could the little bit of scraping done by cable knock d line off balance? it did leave a little mark, nothing deep tho.
I havent opened diff up yet, from what im hearing, it MUST BE an olds rear. I am gonna open it up today, just to see what i can see.
Front suspension seems to be in good shape. Could my tranny be causing this shuttering? or would it do it all the time.
The biggest thing that confuses me is the fact that if i have some one in car with me, the shuttering is almost completely gone,lol
Thanks again Bill, :)
Alan.

Maybe the driveshaft is out of line and when someone else is in the car it straightens the angle enough to make it stop. Is the angle of the driveshaft really severe? Does it have airshocks as most Caminos do? Maybe you could try letting air out of the shocks and see what she does?
I'm not an expert but I do work in a shop that shortens big truck chassis/driveshafts. You cannot always see a problem with U joints/driveshafts just by looking or pulling on the driveshaft. It doesn't take much to throw a driveshaft out of balance. And the angle matters a lot more than you would think. --- Josh--Good Luck

Maybe the driveshaft is out of line and when someone else is in the car it straightens the angle enough to make it stop. Is the angle of the driveshaft really severe? Does it have airshocks as most Caminos do? Maybe you could try letting air out of the shocks and see what she does?
I'm not an expert but I do work in a shop that shortens big truck chassis/driveshafts. You cannot always see a problem with U joints/driveshafts just by looking or pulling on the driveshaft. It doesn't take much to throw a driveshaft out of balance. And the angle matters a lot more than you would think. --- Josh--Good Luck


The angle of d liine is not severe at all, no air shocks on it, gas shocks.
Yea i learned about the angle really messing up u joints,lol, the hard way.
I suppose it could still be u joints, like you said, sometimes u cant always tell my just pulling and what not.
I just opened rear pan, and im seeing chevy 10 bolt guts in it, not olds like some where suggesting, axles has the lame c clip over them, wich as far as i know, this is a distinct chevy trade mark, so 12 bolt housing with non posi set up. I was told this is impossible, but this is what im seeing, anyone got any feed back on this enigma??
Thanks for good info Josh. :)
Alan.

What size are the bolts in the ring gear, and how many are there?

I actually only pulled off pan, so i cant spin it around right at this moment, by bolt size, do you mean what wrench size?
ill have to get back side up in air to count ring gear bolts.
Let me verify that ring gear is the 1 big one on left when i look inside?
Thanks for posting,:)

With car on ground, i can see 8 ring gear bolts,ill have to get it in air to verify the rest, and i know bolts need a 9/16th wrench to pull em,
The number i got off axle tube is KDC 347 1
And i can not seem to get a straight answer to what i have,,
Any ideas??

It could be a Chevy 12 bolt. Count the bolts and let me know. A picture would be nice too.

I wish i could get a pic, dont have camera aval, i will count em, and let ya know, thanks soo much once again..;)

Big Gear Head, i sent ya a pm,if ya didnt get it, here it is..

Ok, i counted bolts on ring gear, there are 12 bolts.
i also counted teeth on ring gear, there are 41
Some of the spider gears look a little beat up, not mangled by you can see nicks on them.
Dont know if this tells ya anything, but on the carrige, i think thats what its called, the center hub like thing that the spider gears sit in have some markings on it as well, they are,
NF
GM 75
L2
Does this tell you anything about my Differential?
Thanks for your time.
Alan.

If i'm not mistaken, The posi "carrier" is different from an open carrier. If you put open spider gears in a posi carrier there will be a lot of slop. That may be where your vibration is coming from.

But its not a posi, its 12 bolt casing, but it looks just like the 10 blt non posi inners.


If i'm not mistaken, The posi "carrier" is different from an open carrier. If you put open spider gears in a posi carrier there will be a lot of slop. That may be where your vibration is coming from.

The # of bolts that hold the ring gear tells weather its a 10 bolt or 12 bolt. The carriers and spider gears look very similar. The 12 bolt is just a little larger. If they removed the clutches and installed spider gears, it will look like a non posi just very sloppy

The # of bolts that hold the ring gear tells weather its a 10 bolt or 12 bolt. The carriers and spider gears look very similar. The 12 bolt is just a little larger. If they removed the clutches and installed spider gears, it will look like a non posi just very sloppy

Ahhh, so u think it is a posi that the guy took out clutches and popped in 10 blt part?
How laame is that??lol,
thanks for the info Furball,;)

That can't be done. If it is a posi then the clutches must be installed or there will be so much clearance in the differential case that nothing will stay in place, including the axles. You just have a standard 12 bolt differential, that's all. You can install a posi in place of the standard differential if you want to. There is no way that 10 bolt parts could have been installed in the 12 bolt, they just don't fit.

Ok, i didnt think chev made a 12 bolt non posi,.
Thanks BGH, I learned something today,:)