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Re: 3.45 Differential install

Posted: Sun Jul 08, 2018 2:31 pm
by Pursuit
Yes, yes they did.


Re: 3.45 Differential install

Posted: Fri Sep 06, 2019 1:52 pm
by 9C1fanatic
Maurice, did you use the a camaro driveshaft coupler? The rubber disc between the driveshaft and the diff yoke. If not did you notice any differences on the caprice coupler mounting to the camaro diff vs the oe caprice diff like someone else on this thread did? Also, did you need to support the lower control arm of the right rear suspension with a jack? It looks like you pulled the bolt out that connects the rear coil spring strut to the control arm.

Got a public relations caprice here at work that is getting some mods and this may be the next step for us.

Re: 3.45 Differential install

Posted: Fri Sep 06, 2019 4:10 pm
by kevink
I'm not Maurice, but I used the Caprice coupler when I installed my Camaro diff. It mated to the Camaro diff exactly like it mated to the Caprice diff. There was no difference. I don't remember having to support the LCA with a jack. Actually, I had to force it down. This is really an easy bolt in swap. Just tear into it and you'll have no problems. Make sure you upgrade the diff bushings before you put it in. I also put steel clutches in mine, got rid of the Belleville washers, and added a Ford S-spring. I hammer it repeatedly every time I take it out and it's been great so far with drag radials on the street.

Re: 3.45 Differential install

Posted: Sat Sep 07, 2019 1:10 am
by Fudgehog
On my 3.27 install in which I also did a lot of rear end work, I noticed a lot of vibration with the Camaro coupler, outside of normal alignment issues.

Upon putting the Caprice coupler back in, I noticed much less vibration.

Re: 3.45 Differential install

Posted: Sat Sep 07, 2019 6:38 pm
by Pursuit
When I did the swap, we lifted the entire car up using the hydraulic jack on the sliding rail between the ramps. The lower control arm just hung there. We might have lifted the lower control arm up to relieve the tension on the upper control arm and toe link. As far as the coupler issue, I did not see any difference, dimensionally. As we have found with other rear suspension pieces, they have been similar but not quite a match. MAYBE, through engineering, design upgrades with the G8, Camaro, Caprice and SS rear suspension over the years, parts might have had a direct crossover at some point.
Without digging into the actual part numbers per model/per year, maybe we need to more closely verify our swaps?


Re: 3.45 Differential install - prop flange bolts

Posted: Sat Sep 07, 2019 9:37 pm
by Navy Lifer
This seems like a reasonable place to post this....I haven't looked back through the 5 pages of posts here to see if the details are already posted.

It turns out the fasteners for the prop shaft flange are critical, TTY (torque to yield), USE ONCE parts.

The topic came up on Facebook on the Caprice PPV pages, and I do understand not everyone can or wishes to go there. The discussion was started by Dustin Manning, in the course of swapping in a 2014 SS rear cradle (if all else fails, search for his posts on Facebook), with many responses...worth a read if you have the time and can get on FB.

The discussion starts with a picture showing that a prop flange bolt was missing on his PPV before starting the job, which "explained" a vibration.

Following is the gist of what I posted, with a few minor clarifications - after I posted the following, the conversation seems to have stopped.

I do admit that the SI (GM online service information) is not well-written that covers this, so it may be a matter of interpretation, and my take is erring on the side of caution as far as replacing flange bolts.

The prop shaft (driveshaft) mounts with different bolts at each end. The transmission (forward) end uses a bolt & nut, where the aft/differential end (aft--sorry, my nautical life influence) uses only a bolt.

The quantities are 3 of each--bolt 92139225 & nut 92228333 at the front coupling, and bolt 92139104 at the rear coupling.

In the SI (Service Information Doc 4088956), there is a NOTE: The nuts and bolts are part of a torque prevailing system and are single use parts. They must be discarded and NOT (their CAPS) re-used.

The full document runs 6 printed pages, and includes information about R&R, inspecting the couplings, torque values for re-install, Torque value at both ends is 66 lb-ft on first pass. Front (bolt & nut) is then tightened an added 52.5 degrees. Rear (bolt) is tightened an added 42.5 degrees.

Here is an expanded CAUTION in the SI regarding fasteners--it is somewhat generic, but covers everything:
Caution: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Do not use paints, lubricants, or corrosion inhibitors on fasteners, or fastener joint surfaces, unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems. When using fasteners that are threaded directly into plastic, use extreme care not to strip the mating plastic part(s). Use hand tools only, and do not use any kind of impact or power tools. Fastener should be hand tightened, fully seated, and not stripped.

Re: 3.45 Differential install

Posted: Sat Sep 07, 2019 11:43 pm
by kevink
That's odd. Post No. 6 here by Crazy Paul indicates that the 92139104 bolts get torqued to 85 lb ft. Any idea why there's a discrepancy?

Re: 3.45 Differential install

Posted: Sun Sep 08, 2019 1:29 am
by Navy Lifer
This is newer SI, but no idea why G8 (or CP) called for a different spec for the same fastener. On the same note, G8 early production had wheel nut torque of 125 lb-ft, and PPV has always called for 140 lb-ft, as has all other Zetas since Gen5 Camaro, with exact same wheel studs.

I'll see whether current SI for G8 has changed.

Re: 3.45 Differential install

Posted: Sun Sep 08, 2019 2:45 am
by kevink
Navy Lifer wrote:
Sun Sep 08, 2019 1:29 am
On the same note, G8 early production had wheel nut torque of 125 lb-ft, and PPV has always called for 140 lb-ft, as has all other Zetas since Gen5 Camaro, with exact same wheel studs.
Maybe that's a good indication that all of this torque spec and fastener stuff is not that critical after all. I mean, how often does anyone ever hear of fasteners breaking or coming of when they are re-used? Never for me. Thanks for looking into whether the current G8 SI has changed.

As a side note, Weld Racing wants us to torque their wheels to 110 lb ft for 14mm studs. That's a difference of 30 lb ft over factory specs and my wheels have not fallen off yet!

Re: 3.45 Differential install

Posted: Sun Sep 08, 2019 3:57 am
by Navy Lifer
Not to question Weld, but has anyone ever asked them about how they determine torque recommendations for wheels, and/or why it differs from OE specs?

https://4aah2h38qz0d1pp9jb46vzfw-wpengi ... ations.pdf

I'm not faulting Weld (you mentioned them), as this seems to be fairly common among aftermarket wheel suppliers....wheel studs are designed to be stretched to a specific amount that will hold against loosening, based on the stud diameter, thread pitch and friction between the stud and nut threads and the friction on the tapered seat of the wheel nut against the wheel. If that "clamping load" is not achieved, it gives me concern that in some way it's potentially going to lead to a problem at some point.

Another way to look at this--the same wheel from an aftermarket supplier can fit multiple vehicles, which MAY have different size wheel studs, yet the manufacturer's torque recommendation is the same? Sorry, I don't think the wheel guys are being smart about the whole issue--unless there's a specific reason otherwise, the proper statement should say something to the effect of "follow vehicle manufacturer's wheel mounting torque specification, UNLESS there is no recommended torque value" which case wheel manufacturer's recommended torque for wheels applies.

I would really like to have a factual, reasoned response from a wheel manufacturer on their approach to recommended wheel nut torque, which always seems to be lower--in some cases substantially--than what an OEM has published for a specific vehicle.

It would also be fair to seek the same answer from the OEM (GM in this case) to explain how torque specs could differ for the same fastener set between models. It may just be more difficult to get a good answer than from the aftermarket.....