3.45 Differential install

[kevink]

I was just messing around with a calculator. Going from 3.45s to 3.91s will only increase engine speed by 258 RPM with a 28" tall tire (what I have). Hardly noticeable.

[JUNKYARD_JACK]

Only reason I ask is I found a 3.91 diff local to me. Now the seller says “something is broken inside and I’ve not taken it apart”. The price is low enough that I’m probably going to get it, take it apart and see what’s happening. What direction I go to from there is all dependent on what is broken in that diff.

[Pursuit]

Is the 3.91 diff out of a ZL1 Camaro? Is it a bigger case? Just asking...

Maurice

[s/c'd cav]

Is the 3.91 diff out of a ZL1 Camaro? Is it a bigger case? Just asking...

Maurice

no , its the same case , its the gear set that was in the 1LE camaro and possibly the Z28

ZL1 is the 3.23 and 3.73 in the large cast iron case housing

[JUNKYARD_JACK]

I believe that it’s a 1LE SS read end. If the gears are ok I thought I’d get a trutrac if the posi unit is ok I think I’d try to re-gear it maybe to a 3.45 or just hit it with a GM performance 3.91 kit or something. I know just enough about setting up rear ends to be dangerous lol so I want to have a unit to tinker with. I’m not scared of dropping the diff so if I rebuild this one and it’s not right I’ll drop my factory diff back in. However if y’all think this is a stupid idea please tell me haha.

All depends on what’s wrong but I could potentially install these and go. This is about what I was thinking.
https://www.strangeengineering.net/prod ... taly.html/

Of course if a 1LE SS broke this rear end it could be completely destroyed. Might be a gamble but I’m willing to take that.

[s/c'd cav]

as long as you are paying about what case value is , its worth it , or maybe cheaper than what the 3.27 or 3.45 units sell for

but at 3.91 working diff prices , then its not worth it

[JUNKYARD_JACK]

I told the dude I’d not be able to pick it up til the first of next year anyway so if and when I go get it I’ll update the situation

[kevink]

I believe that it’s a 1LE SS read end. If the gears are ok I thought I’d get a trutrac if the posi unit is ok I think I’d try to re-gear it maybe to a 3.45 or just hit it with a GM performance 3.91 kit or something. I know just enough about setting up rear ends to be dangerous lol so I want to have a unit to tinker with. I’m not scared of dropping the diff so if I rebuild this one and it’s not right I’ll drop my factory diff back in. However if y’all think this is a stupid idea please tell me haha.

All depends on what’s wrong but I could potentially install these and go. This is about what I was thinking.
https://www.strangeengineering.net/prod ... taly.html/

Of course if a 1LE SS broke this rear end it could be completely destroyed. Might be a gamble but I’m willing to take that.

Changing gears and putting a Truetrac in these is kind of a pain in the ass and you need a lot of special tools (press, case spreader, GIANT race installer tool for the pinion race (I had to make one), torque wrench for reverse threaded bolts, etc., etc. Then you need a pile of shims, two crush collars, extra pinion bearings that you'll need to enlarge the ID of, etc. etc. I'm not trying to discourage you or anything, but it's a shitty job. You would be much better off just getting a good rear with 3.45s in it already if that's what you ultimately want.

[osubeaver]

I've picked up a 3.45 diff out of a 2011 Camaro. I'm having trouble finding a source for the bushings to mount it. I'd like to stick with OEM if possible. I've found sources for aftermarket urethane bushings but in my experience they can be noisy and I'd like to avoid them if possible. I've come up blank at a few online retailers and the local Chevy dealer was unable to source them too.

Does anyone know of a source and part numbers?

Thanks!

[s/c'd cav]

I've picked up a 3.45 diff out of a 2011 Camaro. I'm having trouble finding a source for the bushings to mount it. I'd like to stick with OEM if possible. I've found sources for aftermarket urethane bushings but in my experience they can be noisy and I'd like to avoid them if possible. I've come up blank at a few online retailers and the local Chevy dealer was unable to source them too.

Does anyone know of a source and part numbers?

Thanks!

you are better off doing the urethane bushings , GM doesnt service them seperately