The Camaro Club (UK)

Hi all,

Fairly new here so I guess I'll introduce myself.

I'm Andy and I have a 1991 Camaro RS which was a Japanese Export model. It seems pretty basic with a few nice extras. Its been in the family for about 10 years now and I bought it off my dad a nearly 2 years ago, since then I've been fixing up all the bits that kinda didn't get fixed up. Simple stuff like giving it a full service, new radiator, plugs and leads, fixing various water leaks in the seals and fixing the paint up.

Now I've come to the point where I want to start modding it myself. It runs a 305 TBI, with stock everything. The only thing I did was remove the back box and replace it with a Cherry Bomb straight through pipe. I've done a deal with a friend and have a nice fresh 350 out of a '72 Corvette thats been dyno'd at 300hp peak lined up to fit, but firstly I want to get the chassis and drivetrain sorted out.

First on my list is to replace the open diff with something a bit more tastier. My RPO sticker reckons I have a GU4 back end, which suggests 3.08 gears and no posi. So I'm on the hunt for a Trans Am or similar axle, then I'll start considering getting the box overhauled and uprated or replacing it for a TH350 / 400.

Any thoughts and opinions welcome, or anyone with a LSD they're looking at selling!

I have one posi axle left

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Hello and welcome Andy, and lovely looking RS you have there, and in my favourite colour for a 3rd gen too
The 305 TBI doesn't have alot of power for a V8 as standard, and really can do with a good wake up.. but still nice cars cars, and fun to drive.


The only thing I'd think if you're looking for a higher geared rear end, is you mentioned swapping in a TH350 or 400 gearbox, which is only a 3 speed, and I think you'll have a 4 speed 700R4 auto in yours now which has an overdriven 4th gear.
If you drop down to a 3speed you'll lose the overdrive, and with higher gears you'll be revving the nuts off the engine at motorway speeds (and lose top end speed too).

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“You only live once, but if you do it right, once is enough.”

Hi Rocky, can you give me some more details on it, what type, what ratio, how much? I'm 'Andy' off the MKB forum, so have been speaking to Ryan with the IROC, does recommend you a lot.

Chevy-stu, I've also spoken to you before on Pistonheads, good seeing you on here too. Thanks for the compliments on the colour, love it too, just such a shame no one give me a definitive answer on whether its blue or green!

Regards the TH350/400 conversion. Yeah, thats something I've realised, I wasn't thinking of going too crazy on the gearing, maybe a mild 3.43 set or something like that. Loss of the overdrive would only be an issue on the motorway, which I don't at the minute do a lot of driving. Whenever I'm off the motorway I knock it down into '3' as I get really fed up of it dropping into OD and then switching between locking up the TC and not.

I just like the idea of it being a much stronger box stock, than the 700R4 was stock.

I don´t think your motor will "kill" the 700R4.

What about the new 350 I'm planning on putting in there? It's peak output is around 355 ft-lbs from 2250rpm to just over 5000rpm. I've just read a fair bit about them not being as strong as the TH350/400's.

By the way, new on this site but I love your car. Hope to have mine somewhere similar in a few years!

What you going to do, drag race it ?

You have the latest model Camaro which also came with the 350tpi motor,
they live behind them.

My motor´s output.....apparently.


I´ve had a PowerTrax in my rear end.. ..for a very long time, works perfect without all the hassle of clutches etc.

Drag race it / just make it look and go a bit better! The 305 TBI is a pretty big let down in the performance realms.

The only reason I thought the 700r4 box might not be up to it, is at best they would've only had to put up with about 225hp from the 350tpi motors? Then they uprated them for the LS engines when the 4th Gen came out. Willing to run it until it dies though, will probs need to upgrade the convertor at some point though as thats stock.

Ah, my old man had one of those lockers in his RS and it was awful and notchy. I drove it once and the damn thing nearly bit me hard on a corner, was very unpredictable! Got it sat in a box at work with the carrier. I like how they're maintenance free, but pretty sure his wasn't right.

Sounds like you know what you're doing and what you've got..
I thought the 700R4 was OK if handled gently enough, but will fail if fluids cooked and mistreated. You can get them built up pretty strong by loads of companies now, so personally I'd stick with for less hassle and the overdrive benefits. Also, you could put even higher gears in, 3.73 or something, if you want to leave the line quicker.
I had my old TH350 fail twice, so ended up going manual as that's what I wanted anyway.

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“You only live once, but if you do it right, once is enough.”

You have too choose the rear gear carefully as the TH700R4 has a very low first.
I was told to go for 4.11 rear gears but the adviser was only thinking of the overdrive ratio.