68 differential disassembly & recon

[Jeff]

I feel the info was a 5 page commercial for Stewart Components. It said that you should both use and not use a restrictor/t'stat. I haven't changed my thinking yet but I am still waiting for you to install your $7 restrictor kit, as I feel you owe us all that much for having started all this. ;)

JP

[Tom B.]

Yes, By all means.....

Jeff,

I found plenty of conflicting information. And yes, the plans are in the works for me to acquire and test the restrictor/reducer kit. I am glad I waited for more information as I had intended to include a run without my thermostat but am completely reluctant to at this point. I need a few weeks to get it worked into my schedule, and I haven't had time to even drive the car in the last couple of weeks. I will plan to post results, especially to the "bordom" of all that lost interest. :) Tom #24014

[Jeff Conner]

68 differential disassembly & recon

I am wanting to disassemble my differential to replace seals, blast the casing and yokes and clear coat the casing (maybe even powdercoat). The chassis and service manuals give no info at all about servicing the differential. Anyone have a service manual on this or know of any information available?

[George R.]

Re: 68 differential disassembly & recon

Call 4 Speeds by Darrell Shepherd 1-800-365-1102, he can probably help guide you in the right direction. He just rebuild my 67 rear end exactly like you mentioned. He stands by his work also.

Good luck,grr#33570

[Jeff Conner]

Re: 68 differential disassembly & recon

George, I am wanting to do the work myself, not send it out. Do you think Mr. Shephard could and would provide the manuals or info I need?? It seems that most of the time the guys who do it for a living are somewhat reluctant to provide the info and I can't blame them for that.

[George R.]

Re: 68 differential disassembly & recon

Jeff:

It's a toll free number and tell him your an NCRS member. I doubt he would provide you with a manual but may be able to give you advice where you can get a manual or maybe he'll fax you a copy of what he uses (ask). There isn't all that much work involved.

Just ask if he could assist you as you want to do the work yourself due to $$$$$. I'm sure he would understand that reasoning whether true or not. Give it a shot you have nothing to lose only to gain. He's a nice guy and honest.

Good luck,grr#33570

[Joe L.]

Re: 68 differential disassembly & recon

Jeff-----

The manual which you seek is the 1968 Chevrolet Chassis OVERHAUL Manual. This is a companion manual to your Chassis SERVICE Manaual. For your purposes, just about any late C2-early C3 overhaul manual will do, but if you're going to buy a manual, it might as well be the correct one for your year model. I believe that you can obtain this manual from the NCRS bookstore.

Notwithstanding the above, disassembly and re-assembly of the Corvette differential unit is not really a task for the inexperienced and those without special tools. However, I think that this will be clear to you after you review the procedure in the overhaul manual.

[Joe Ciaravino]

Re: 68 differential disassembly & recon

Jeff:

I completed rebuild of my 1965 diff. (same Eaton unit as your 1968) last month. Like you, I also wanted to do it myself. I ended up rebuilding the posi unit(diff. carrier assembly) myself, and sending the case, carrier,ring and pinion etc. out to complete the setup. The ring and pinion backlash, and bearing preload is much too critical to attempt yourself. Any good transmission shop should be able to handle this job. I would also recommend one of the Corvette specialists like Van Steel. The owner, Art, is a good man, and very helpful.

Setting up the carrier ass'y. is a straightforward job if you have a dial indicator. Always change the 4 preload springs, and carefully examine the clutch disks for signs of wear/overheating. These are relatively inexpensive at about $90.00 thru GM.The most CRITICAL thing here is the side gear-to-spider(pinion) gear clearance. GM recommends a range of .001-.006 clearance, and that will determine the preload on the clutches, and therefore the effectiveness of the posi unit. During assembly, you must coat all parts, esp. the clutches with a mix of gear oil and posi additive. I set mine to .002, and upon completion, I measured the clutch "break loose" point at 50 ft-lbs with a torque wrench (GM recommends AT LEAST 40 ft-lbs.).

As Joe L. said, get yourself the 1968 Corvette shop manual (available on this website) before proceeding.

Good luck, Joe