42 replies to this topic

[Blair]

Team,

 

This question will have been asked before, but I am doing the good old UC hatch conversion to A9X replica.

 

See in the picture the diff, my question is - what diff should I put in there? my budget isn't massive. I want to put an LS1 in it so the diff will need to be strong.

 

Is the one in the picture from the original 3lr engine? I'm guessing this would be no good?

 

I've heard an 8 inch ford diff would be ok? however I am option to suggestions. My knowledge is very limited.

 

Cheers 

Attached Files

•  Screenshot 2021-09-30 175059.png   236.08K   13 downloads

[308 Sunbird]

G-day Blair, yep that is the standard 4/6 cyl diff all UC's came with. An LS1 will kill it pretty quickly if you wanted it to. 

I would have either a large Salisbury or Borg Warner 4 pinion diff made up if it was me but others will tell you to

get a Ford 9 inch made. I just don't like anything with F@#d written on it     

[Blair]

cool thanks. what cars do those diffs come out in? and when you say made up do you mean alter the mounts etc to fit in the car?

[Bigfella237]

These days you can actually build a 9 inch without using any F-word parts. But either way you do it, a 9 inch will cost you decent money.unless you can scrounge one second-hand?

 

On the plus side, you pretty much have your choice of ratios, centres, axles, yoke/uni, etc.

 

Alternatively, have a search around here for a Borg Warner conversion, or I think it's an R33 Skyline diff conversion too, neither will be as strong as a 9 inch, but will be considerably cheaper.

 

What you need depends more on your driving style and the intended usage, the diff you have now may last forever if you drive it really carefully. But if you're into drag racing or drifting then spend the money and do it right the first time, in my opinion of course!

[rexy]

You can have a nine inch with no factory ford parts if you are F**D averse.

 

Get a reliable well known business to build one for you. Budget about 3 - 3.5 K for one you will never kill.
 

Don’t be in a rush to get it done. Make sure you pick your wheel and tyre combo and preferred brake setup before you get it made.

[dattoman]

http://www.gmh-toran...bw-diff-to-lhx/

[Bigfella237]

I thought the 3.9 diffs in the old Crown's were an Aussie-sourced banjo centre?

 

I remember grabbing them whenever one came up for speedway use, the centres bolted straight into a Holden housing but I think they were fine-spline axles (stretching my memory on that though).

[Ice]

If you are going to play silly buggers with an LS1 in it just get a 9 inch 

[LXCHEV]

Nothing wrong with a good Borg Warner conversion, but I hate to say it - I too, would just follow the tried, tested, proven, and simplistic approach of a good old fashioned "Ford 9" style setup. You can pretty much buy them at your local 7-11 these days. Parts are plentiful, you will have endless, endless (and plentiful) options for all components - centres, LSDs, true-tracs, lockers, aftermarket axles, pinions, brakes.... it's all just so easy. And because there is so much supply, you might find a lot of components end up being cheaper than other style conversions.

 

100% with rexy's advice - decide EXACTLY what your plans are and what your requirements are first (even up-spec it slightly). Then get it built by a reputable shop. Don't skimp on cash - do  it once, do it right. Make it bulletproof from day 1 and then you will never, ever have to worry about the rear end for the lifetime of the car (within reason).

[Blair]

The post from Neil looks good... would you recommend that?

 

And when you say a ford 9'' which ford 9" exactly? from what model and year?

 

Cheers 

[Bigfella237]

It doesn't really matter what model/year of ford that the diff comes from, it will not fit the Torana without being converted.

 

The leaf spring mounts will need to be cut off and some suitable Torana mounts welded on (in the correct place, of course), then the ends get cut off the housing and replaced, shortening it at the same time, then you either fit billet axles or some other axles that are the correct length, size, spline count, stud pattern, etc. and suit the brake package of your choice.

 

If you're going down that road, just find a conversion place and get them to supply everything ready to go, some may not even take a donor diff.

 

All that costs money, as Rexy said, probably around $3k~$3.5k all up.

 

If you're on a budget, look around for a second-hand 9" out of a Torana, there would be thousands of them about so it's just a question of finding one, although finding one from a UC will make your task a lot harder (different suspension mounting points from the earlier models).

 

You may pick one up for around $2k but you might not get the exact ratio you want, so factor that into the budget. Also, people don't fit 9" diffs to drive to the supermarket on Sunday so just be aware that you might be buying something that's been used and abused.

Edited by Bigfella237, 01 October 2021 - 01:06 PM.

[Blair]

I found a 1996 VS commodore diff with 3.08 ratio 5x120 ratio. Its borg warner, only $600 so might just run with that I think

[rexy]

It will need a lot of modifications to fit it to your car and you should price those before you buy a “cheap diff”.

You also end up with commodore pattern which sucks for wheel choice.

[Blair]

does that pattern not fit any sort of hotwires etc?

they reakon those 9" ford diffs are noisy

[Bigfella237]

I'd guess "they" might be talking about a Detroit Locker centre, and yes they can make a 'clank' as they lock up, but if that worries you then use some other kind of centre, there's probably a dozen different types to choose from ranging from a factory LSD to a Truetrac.

 

I reckon you'd be far better off puting that $600 toward something that's gonna last longer than a Commodore diff though. If it's from anything less than a 5.0L Commodore then it's not really any better than the Salisbury you've got now... and you still have to get it shortened & converted!

[Ice]

does that pattern not fit any sort of hotwires etc?

they reakon those 9" ford diffs are noisy

 

does that pattern not fit any sort of hotwires etc?

they reakon those 9" ford diffs are noisy

No Commodore is PCD 120 mm HQ  to HZ 120.65 mm 

Hotwires need to match stud pattern 

[Ice]

I found a 1996 VS commodore diff with 3.08 ratio 5x120 ratio. Its borg warner, only $600 so might just run with that I think

First    that will go bang 

[gtrboyy]

Go with the 9 inch so that can abuse hell out of it & still make it back home.

[Blair]

what about V8 Salisbury 10 bolt 3.08 gears with 28 spline? says it needs new spider gears. don't know what that means. 

[Ice]

what about V8 Salisbury 10 bolt 3.08 gears with 28 spline? says it needs new spider gears. don't know what that means. 

It means you will have to take it to a diff specialist to have new spider gears installed

V8 Salisbury are ok but you still have to modify brackets ,stud pattern, tail shaft etc etc 

Just start with a 9 inch and just spend the same money on that 

[Blair]

OK something like the one in photos?

 

 

1600 for that bad boy

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•  diff.png   381.73K   5 downloads
•  diff info.png   10.28K   4 downloads

[Rockoz]

Pretty sure the diffs in Commodores from VL on are a BW78.

Same diff as Ford, Nissan and many others.

They are supposedly rated at 500hp.

As strong as the original "big" salisbury fitted to 308 V8 Holdens?

 

Lots have used them for getting some serious horsepower to the ground.

Lots of ratios and heavy duty bits available too.

 

Cheers

 

Rob

[Bigfella237]

Again I would advise that you talk to some diff conversion places before you spend any money, you might be wasting your money buying something they can't (or won't) use?

[Heath]

Hmmm... I must say I think I would feel pretty confused if I was Blair after reading this thread. There's some good stuff here and some misleading stuff.

 

Blair, give me a call on 0400 152 789 and I will discuss your options without some of the silly shit like claiming a BW can't handle the almighty grunt of your motor because it's an LS. : /