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Old 04-09-2010, 02:06 PM   #1
TNprogrammer
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inspecting a differential

I'd really like to pull off the differential, clean the outside of it, paint it and re-install it. Also, I'd like to open it just to get a quick "visual" to see how it looks. Is unbolting and re-installing it a big enough paint that it's only worth it if something is really wrong, or would this be a worthwhile endeavor? Can you see much of the inside without completely disassembling it?
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Old 04-09-2010, 04:31 PM   #2
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I would read my threads. A stock 79 and some of the common rebuilds are not all that good to start with. Areas where you ned to look:

Yoke endplay, Ring gear bolt type and torque,Posi clutches,pinion seal and yoke seals.

If you remove the diff and have endplay over 050" then check it, chances are good they're worn but also the posi's are loose.

You can very easily end up rebuilding it. If it's not leaking,hammering, or has under 050 endplay, leave it alone and drive the car. If you're going to rebuild, then do it right the first time.

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Old 04-09-2010, 10:40 PM   #3
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Gary,
I've read several of your posts and while very interesting, most of it is over my head just because I have no idea what a lot of the stuff is that you're talking about I'm learning all I can but a lot of that rebuild stuff is Greek to me. I now know what non-technical people feel like what I start talking about computer programming to them
A lot of parts on the underside of my car really just need to be pulled off, cleaned up and painted. I love the way those diffs look in your posts after you've blasted and painted them. The only thing my car is doing in that area that I think is weird is when I first start it up and put it in reverse or drive it sounds like I just dropped my rear end on the road. Granted, it is idling pretty high since it is cold. Some people have told me this is normal, but holy crap! One transmission guy I talked to on the phone said I might have some slack in my driveline. I hear no knocking at all while I'm driving and it shifts really smooth going through first, second and third. It's just moving from park that it sounds like my rear suspenion just fell off

Anyway, back to my original question...would it really be that big of a job to just pull off the rear diff and clean and paint it, along with any other parts in that area I might be able to get to?
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Old 04-09-2010, 11:50 PM   #4
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Gary is giving you some sound advice.

It doesn't sound like you want to rebuild just yet. You might want to consider just cleaning and painting what you can while it is installed. Once you remove everything you will probably want to start fixing everything $$$.

Just my two cents, for free of course.
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Old 04-10-2010, 06:35 AM   #5
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Sounds like the snubber bushing is bad. Look to see if any oil is leaking on it from the pinion seal. They compress and dry rot causing the diff to move under load.
Yes you can pull it and paint it, that's just your time to do. I know the areas I mentioned will need attention, they always do. The question is what do you want to do? I would not attempt to blast it assembled then you will be rebuilding it once the bead gets into the bearings.
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Old 04-15-2010, 01:23 PM   #6
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OK...last night I put the car up and spent some time under the back end to see what things looked like. Here are some pics:








Things are pretty wet. It almost looked like it was leaking at the fill hole, but I checked and the bolt is tight. It also looked like there was a lot of sludge around the cap gasket, so maybe that where it is leaking. I checked the connection at the drive shaft and that was dry, so maybe the snubber is OK? Notice how shot those bushings are. They're not just shot, they're practically non-existent
Anyway, I think it's evident that things need to be pulled and looked over. I'll probably be asking questions on how to get this stuff down. I'm sure there's already some good info on here about that.
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Old 04-15-2010, 02:51 PM   #7
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Looks like a 30-year old untouched IRS. The diff is leaking, could be from the fill plug but probably from the pinion seal and/or yoke seals. The strut rods need new bushings, Joints are probably worn as well.
To correctly repair these, the IRS and Diff should come out.
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Old 04-15-2010, 03:07 PM   #8
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I think I may just replace the struts rods. Is this set from eckler's OK?
http://www.ecklers.com/product.asp?p...8&dept_id=1843

I may get to work removing everything tonight. In what particular order should I start pulling stuff off? I'll be removing the spring (to be replaced by VB&P composite), the rods, the diff and the shocks. Am I missing anything?

Last edited by TNprogrammer; 04-15-2010 at 04:26 PM.
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Old 04-15-2010, 05:42 PM   #9
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If the rear alignment has been good all you need are new bushings- press out the old and press in the new. Nothing to loosen up,nothing fancy just less money and they work. when I do them I blast, POR15 and top coat them. You can do the same with a wire wheel on a grinder.
Drop the spare tire comb & exhaust.
Mark the camber position on the rod camber bolts
Disconnect the pinion yoke strap and slide the DS forward a little or remove it noting the front and rear ends.
Disconnect the 1/2 shafts at the diff and spindle flange.camber out and remove shafts.
pull camber bolts and swing down or remove strut rods.
Place jack under diff
loosen and remove 1 crossmember bolt, install longer bolt & washer to "catch" the cross member.Do the same to the other side.
Use a long bar-3-5' to pop the cross member off the tapered sombero's. Lower and remove the diff.
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Old 04-15-2010, 09:55 PM   #10
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Thanks for the info Gary. I thought I'd at least try to clean up/paint the strut rods and see how they look before I replace them. How hard is it to remove and press in new strut bushings? I'm definitely going to replace the old 9 piece leaf with the monospring. What pound rear monospring do you guys usually use?
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Old 04-16-2010, 11:24 PM   #11
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Quote:
Originally Posted by gtr1999 View Post
Mark the camber position on the rod camber bolts
I'm not sure by what you mean with the rod camber bolts. There doesn't look to be anything adjustable on these rods. They are one solid piece. The only bolts are the one that fasten them to the car at each end. I'm sure I sound pretty ignorant by now

BTW...one of the rods is actually bent. Think I'll end up replacing them.
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Old 04-17-2010, 03:45 PM   #12
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The camber bolts are what adjust the camber, they are under the diff in the rod bracket. You mark the position they're in before moving the rods so you can get them back in position. Since you have a bent rod, someone was back there probably during an alignment for compensate for a weak spring, worn bushings, or slop in the diff side yokes. I have seen vette shops heat the rods and rebend them back but I never liked that approach. I still would stay with solid stock type rods too.
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Old 04-19-2010, 10:02 PM   #13
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Well, I'm removing the shocks first. I got the driver's side shock off today(which is absolutely shot), but the top bolt on the passenger side shock is being stubborn. I've been soaking them for the last few days. I've used a torch plenty of times to heat a bolt so it will break free, but never one soaked in oil. Shouldn't I clean as much oil off the bolt as possible before I torch it? Seems like common sense, but just thought I'd check
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Old 04-26-2010, 12:03 PM   #14
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OK...Both shocks are out. Both long bolts are out at each end of the rear spring. Now I just need to unbolt the spring from the diff and drop it out. Man, some of these bolts are STUBBORN.
I wanted to ask what pound monospring you guys would suggest from VB&P for normal driving (300#, 330#, etc.) Also, what are some nice shocks for everyday driving?
Both of my shocks were so shot that when I pushed them in by hand they wouldn't even expand on their own.
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Old 04-26-2010, 03:00 PM   #15
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If your camber arms are going to be replaced, I am very happy with these from VB&P...


http://www.vbandp.com/detail.aspx?ID=497

They retain a bushing at each end to avoid the harsher ride that Heim joints can cause, but allow for much easier camber adjustment by doing away with the excentric bolt and washer, instead using Left and Right threaded ends, so that adjustment is by turning the shft then locking it in place.

I have a 340lb composite spring which I am reasonably happy with, but if I had to replace it, I would go up to 370lb.

I use Koni adjustable shocks, but just because your shocks don't spring open, doesn't mean thry're shot.
Some shocks don't spring open, that isn't the purpose of a shock. Try opening and closing them and try to gauge how hard it is to move them quickly. If both shocks feel the same, the chances are they're fine.
That said, many people reckon that shocks valved specifically for the composite springs are a big improvement over those designed for the steel spring, so you may want to change them for that reason.
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