jbakyy

Hello,

I have a oil leak in rear end for 1971. Does anyone have any tips or suggestions?

Thanks

Sigforty

Where is it coming from? Is it the front yoke, side yoke or rear cover?

jbakyy

i think side yoke

Sigforty

Chances are you need to pull it apart and replace the seals. The only way to remove the side yoke is to take off the rear cover to gain access to the retaining clip. If you are going to have to do that, you might as well do a rebuild and replace the bearings as well.

jbakyy

thanks, i can't do that, i'll need to get someone to do it. is that a very expensive job? do any of those seal leak preventatives work?

johnt365

I just did this job by myself. If you have a good floor jack and air tools then it is not that bad.

I just replaced the side seals though and did not dig in further than that.

Gordonm

If the rear is still performing well and no other issues are in there you can remove the axles and replace the seals and go back together. The seals are cheap but it is time consuming to do. You might find that the axle tips are worn and may have to replace them as well.

johnt365

I wouldn't have done it without Gordonm's advice. He is an expert and very helpful.

birdsmith

Not sure what the limit is for bearing wear but you can normally check it by prying the ring gear back and forth then measuring the distance that it moved...typically any more than 1/8" would be out of limits. At any rate you'll have to pull the halfshafts, drop the diff, then open it up just to get the side yokes out so you can replace the seals. Likewise, you'll have to remove the front yoke to change the pinion seal, and as long as you've gone to all the trouble to get the diff out of the car you might as well change all 3 seals. Bearing wear can also contribute to seal wear as it can allow the side yokes to move up and down slightly. As for those 'leak fixer' products you were asking about, don't bother...none of them work. As said before it's a big job but Corvettes have big clunky parts in them so they're hard to break...not that difficult to do; just a major PITA.

Gordonm

Your talking two different things here. If you are prying the whole carrier to the left and right yes this is kind of measuring bearing wear. If there is 1/8 of an inch you have major probelms. This is usually measured in thousandths of an inch. If you are rotating the ring gear for and aft you are measuring backlash. You still need a dial indicator to measure this as it should not be more than .015. I try and set used gears to .008 to .012. range. It is really tough to measure bearing wear, I will usually replace them if they are visibly worn on the races. There is almost never a roller bearing that has clearanced itself unless catastrophic damage has occured or it has seized. The bearings in these rears are pretty heavy duty, even the side bearings are pretty tough bearings. If you have it out might as well replace all the seals, easy to do when it is on the bench.

Duane4238

Hold everything! Before you go tearing things apart or paying big bucks for someone else to do a big, expensive job, I have another suggestion. My '72 had the same leak on the right side over 3 years ago. I bought a product on Ebay called Sealube. It softens and conditions hard, dried out rubber seals. It can be added to oil for engine seal leaks and trannies, too. I used it a different way. First, I used brake cleaner to clean up the leaky area on the diff. Then I used a small paint brush and applied the sealube directly on the seal at the yoke. I let it sit for a day and then started driving the car. That was over 3 years ago and the leak hasn't returned yet. It took about 15 minutes and I didn't have to tear anything apart. I'm sure someday I'll have to replace the seal, but not until it starts leaking, again.
Duane

birdsmith

Gordon(?) I must defer to you here...I got that figure years ago when the Dana 70 in my motorhome went poop. Not exactly apples vs. apples. I didn't have a Corvette manual at the ready so I just threw that number out there. I figured it would be a little excessive. And 1/8" IS 125 thousandths!

jbakyy

very interesting, so you just brushed sealube all around the seal on exterior of gear housing? thanks

jbakyy

can you send a link for the sealube? thanks

Rally68

The diff cover is bolted to a frame crossmember on top and the rear spring on the bottom. It is a straightforward job, but it takes time. I'm guessing the estimates you receive will give you heartburn. You may find that you could go out and buy all the tools you'll need (floor jack, jackstands, puller, compressor, impact gun, sockets, torque wrench), to do the job yourself and still come out a few dollars ahead...plus you'll have the tools for the next project. There are countless posts on the forum with pictures and procedures, and countless guys on here who are happy to answer questions.

I wouldn't pour any stop-leak type product in my differential unless it stated clearly that it was safe for posi clutches/didn't interfere with friction modifiers. Even then I wouldn't do it.

If you decide to have a shop do the work, make sure they know and use the correct torque specs--in particular, the spring bolts must be evenly torqued to 70 lb-ft with the weight of the car on the spring, otherwise you risk cracking the "ears" off the diff cover and you get to do it all over again.

jbakyy

thank you

jbakyy

hello duane, what is the link for sealube? i found several. thanks

Duane4238

Just went to the garage to get the bottle. I don't have a link for you but here's the manufacturer's information. It's made by New Technology International. P.O. Box26198. Fraser, Michigan 48026-6098. Phone is 1 800 434 9192. Fax is 1 586 758 6549. Front of 8 oz. bottle label says SEALUBE seal expander. Positively stops rubber seal leaks in any fluid system. For: Power Steering seals, Rack and Pinion seals, Transmission seals, Crankshaft main seals, not for use in brake systems. It's part no. 4008 and it cost me about $14.00. I still don't have any leaking on the rear end of the '72 and it's been a few years, now. Also on the label it says it does not contain petroleum distillates which can destroy seals after temporarily expanding them. Others have commented negatively on the product but have not tried it. All I know is that it saved me a heck of a lot of work for about a 10 minute application. Good luck and let me know if you try it! Enjoy the heat, today. Won't be long before we're up to our #$%@$$ in snow!
Duane

Duane4238

I just googled sealube (should have done that first) and the address is:
www.newtintl.homestead.com/seallube.html
You can order directly from them and it's $14.95
Maybe some of the negative-Nellies should go to their website, too, and read about their products. There are actually products that are being used in the 21st Century, now, that do what they say and actually work, unlike the old snake oil products from the 19th and 20th Century.
Duane

jbakyy

wow & thank you!! sound like a great starting point. so you you just brushed it on the seals on the exterior of the gear housing?