DRB Rear Ends

[G1947]

G'day All
I need some help from the experts here, please.
I was originally going to use the Drum braked LX Torana rear end that came out of the donor car.
Now that I have to use an LS1, I am thinking maybe I should go up a bit in strength and to four wheel discs.
The VN/P/R Commodore is readily available. Does anyone have comparable width measurements of the Commodore and Torana? (Say outside of Drum/Drum to outside Disc/Disc, IE Wheel Mounting faces?)
Will the Commodore fit the early DRB? Mine has the rear cross member notched for a 9", so I assume it will fit that way.
And do the mounting points on the Commodore rear need to be moved if it will?
And, if I use the Commodore rear, what front discs will fit the Torana Stub axles to keep the stud pattern the same. Will VT fit?
And, if I change both ends, can I still use the Torana Master Cylinder?

Thanks
Garry

[400TT]

Yeah, that LS1 will spit out that Torana rear-end in no time. Even if it is a fine-spline axle version it will not last, unless you are really gentle. Glad you thinking things through.

The cheapest, strongest rear end with most flexibility is still Ford 9".

You can just find a shortened Torana 9" housing 2nd hand at swap meets and have a choice of just about any ratio, lsd type and axles(28spline, 35spline, billet etc). These are dime a dozen and should require very little modding, if any, to fit.

In saying that. A guy up here runs a DRB with a Commodore rear end. I think it is an early VN/VP live axle. LSD centre. He runs 347 stroker with Tremec 3550 and it is compaigned heavily on the track. Would race it every 3rd weekend on average and does the most k's of any car in the club. He would probably do 20,000k's a year in his Cobra. He know he recently rebuilt that rear-end, but I think it was mainly due to wearing out the LSD. Then again the stroker has also been rebuilt due to high k's. It has not been shortened, just modded with Torana pickup points etc.

Yep, you can buy some great Torana to Commodore brake conversion kits from Hoppers Stoppers etc. Seen lots of DRB's running VT rotors. Skyline 4 piston caliper seems to be more popular caliper choice these days.

It's really important to get brakes and rear-end sortly properly from the start. Just for the sake of ordering wheels, as once you have them you are stuck with stud pattern & offsets, which makes changing things later more expensive and/or restrictive.

Also with non-shortened Commodore option, you will lose the deep dish look at the rear.
The Torana Ford 9" option will give you that glorious Cobra deep dish on rear wheels.

I'll see what I can find out for you.

[G1947]

Thanks Craig, I am learning quickly that I can rely on you for sensible build knowledge. It will not be driven gently, so needs to be strong.
I know from my younger days driving a string of V8 Fords how tough the 9" is, but I had sort of discounted it because it is heavier than the Commodore, and more expensive to buy. I can get a VN/P/R rear end from the wreckers for $200 - $250 disc to disc. Haven't seen any LX 9 inchers anywhere near that cheap. Then if I use VT fronts, I have all Commodore stud pattern with a huge choice of wheels and tyres. (Still not sure if I need to change the master cylinder though.)
The other advantage of a 9" of course is it is quick and easy to change centres. Not an option with the C'dore diff, but I don't plan to change it out too often. It will be set up as a daily driver with a four speed auto and highish diff ratio for economy. Figure I have plenty of power with the LS1, our SS is no slouch, and it is almost double the weight.
Regards
Garry

[400TT]

Originally Posted by G1947

I can get a VN/P/R rear end from the wreckers for $200 - $250 disc to disc.

Garry, I'm no expert. Just blessed to have built one of these before.

It's amazing, it's been nearly 10 year since we looked into the options. And back then 2nd hand Torana 9" rears were abundant and Commodore rears were expensive. As you say the Commodore rears are cheap and I bet the Torana 9" rears are getting difficult/more expensive these days.

You have to add in cost of modifications to fit the Commodore rear. Or just the time and materials if you can do it yourself.

I'm not that familiar with Commodore rear ends. But you will definitely want to find an LSD. LSD in a Cobra is essential. Not sure if the V8 rear ends were stronger, but if they were you will definitely want one of them.

So you must not mind not having deep dish wheels on the rear.

I'll grab details of fitting Commodore rear into an old DRB. I know a few people who have done it.

Also connected with rear ends, is decision on suspension. Go with the cheap and easy Torana/HQ Springs & cheap gas shocks, like Monroe's. Upgrade to Koni adjustable shocks. Or go the full hog and fit AVO Adjustable Coil Over Shocks.

[G1947]

Originally Posted by 400TT

Not sure if the V8 rear ends were stronger

Opinion on a Hot Rod site I also frequent is that the same diffs were used in V6/V8, only the ratios are different for sedans/wagons etc, and yes, I will be looking for a LSD.

So you must not mind not having deep dish wheels on the rear.

You have got me on this one. I LOVE the deep dish look.

Also connected with rear ends, is decision on suspension.

Because I started this build 8 years ago, I have most of the parts. Stripped a rusted out LX for the front and rear ends, bought most of the other bits over a couple of years, everything straight out of the old DRB manual. So I have Kings springs, Monroe shocks etc. Any changes I make now will mean more $$$$, or, I can use what I have to get it registered, then change things a bit at a time later.
I plan on registering it unpainted (I really like swimming pool blue )and running it around for a while anyway, it is really the wheel choice that is the biggest cost if I get it wrong.
Regards
Garry

[400TT]

Going with Commodore rear, then adaptor kit for reasonable Commodore(like VT) brakes for the front. Then wheel stud and offset will be pretty well right for any upgrades.

This will allow you to eventually upgrade to the larger HSV front & rear rotors. And/or put on Skyline 4 piston on front, Skyline 2 piston on the rear. And none of this will affect wheels. Not sure what size you are thinking, but will need 16" wheels to clear these options. 17" would be sweet. Depending on rotor size, Skyline 4 pistion calipers can be a bit of a squeeze. You could always run some cheap aftermarket Commodore wheels.

Yeah, since you have them, go with your existing springs & shocks. You can actually upgrade later to koni's or AVO's without affecting anything else.