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#1 davelh

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Posted 07 October 2020 - 05:55 PM

Looking at my options for a diff.
Was set on an R31 BW but they are few and far between, and people want stupid money for them when they are available.
I want to keep torana stud pattern as I don't want to change wheels, so I am thinking of my options.
What opinion do people have of grafting the drums off my banjo onto another Borg Warner and having it cut to size with new axles to suit? What other options have people got to keep the stud pattern?
Cheers,
Dave

#2 yel327

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Posted 07 October 2020 - 06:28 PM

Not hard to do with any diff, just get billet axles made. There are plenty of options available if you don’t want a 9”. Camaro 10 bolts come up regularly quite cheaply, but having the cast centre will probably have the same issues with welding on upper control arm mounts as a Holden 10 bolt. Volvo diffs will work too and already have the early Holden stud pattern.
You could try a Hilux diff too, with new billet axles.
How much hp?

#3 yel327

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Posted 07 October 2020 - 06:34 PM

Example Camaro diff:
https://www.gumtree....opytopasteboard

Same diff as HK-HG, just with Camaro perches, axles and brakes.

#4 davelh

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Posted 07 October 2020 - 06:42 PM

Thanks for that. Not sure on HP yet, will have to wait till its built. 355, H284, 650 DP, VN heads, Harrop dual plane etc etc.

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#5 arrimar

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Posted 07 October 2020 - 06:44 PM

Why not keep the banjo housing and brakes, add a trutrac centre and some good axles and enjoy. Minimum fuss.

There is an even cheaper option though.

#6 davelh

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Posted 07 October 2020 - 06:46 PM

Would the banjo be up to it? I wouldn't be opposed to it, but no point if its just going to shat itself every week!

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#7 Lazarus

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Posted 07 October 2020 - 08:43 PM

Depends what ratio you want too. Hilux diffs are limited to 3.55s I believe and Volvos are about the same. Borg Warner and 9" have cruising ratios.



#8 rexy

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Posted 07 October 2020 - 10:42 PM

Would the banjo be up to it? I wouldn't be opposed to it, but no point if its just going to shat itself every week!

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it’s ok, you get very good at removing and refitting centres after a while and knocking out broken axle ends is pretty easy....



#9 Statler

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Posted 08 October 2020 - 10:10 AM

If you are going 355 i think your engineer might insist on a brake upgrade .  :dontknow:



#10 mick_in_oz

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Posted 09 October 2020 - 09:20 PM

9", any ratio you could ever want, any accessory you could ever want, stronger than you are likely to need, build it to take VS Commodore brakes, or maybe just put Wilwoods on it.



#11 yel327

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Posted 09 October 2020 - 10:00 PM

^^I agree with Mick, just assumed you didn’t want a 9”.

#12 claysummers

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Posted 09 October 2020 - 10:03 PM

Heavy


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#13 davelh

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Posted 09 October 2020 - 10:31 PM

I am not opposed to a 9 inch, but feel a borgie is better suited to the car. My biggest problem i think is wanting to stick with torana stud pattern.

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#14 yel327

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Posted 10 October 2020 - 06:21 AM

That is not a problem, just get axles made in Holden pattern whatever diff you choose.

#15 mick_in_oz

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Posted 10 October 2020 - 10:10 PM

Yup, new axles, ANY stud pattern you want, just gotta ask.

 

Heavy? Really? Can't imagine a 9" being much different to a Borg Warner or Salisbury style housing with that large cast center, last 10 Bolt I had to move weighed a heap.

Early style 9" housing with the small onion would be my choice, save a bit of room, and weight if you're hung up on that. 



#16 mick_in_oz

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Posted 10 October 2020 - 10:20 PM

I just found the following in an old thread, stuffed if I can work out how to properly quote someone, but here's a copy and paste.

 

So much for the weight argument....

 

'Quagmire', on 24 Nov 2011 - 21:45, said:snapback.png

the only advantage a borgie has over a 9 is 70 odd kgs of weight....but you need special tools to change the centre if you break it


That would have to be 70 extremely odd kgs of weight. The 9" would have to weight in around 130 kg to be 70 kg heavier than a BW M78. If you a going to compare weights of diffs they really need to have the same type of centre.

Banjo 3.08 open centre, axles and oil, no brakes. 50 kg
9" factory iron LSD, factory 31 spline axles and oil, no brakes 70.5 kg. (Iron housing with LSD centre 32 kg. Housing 22 kg, axles 16.5 kg)
9" alloy Truetrac, Moser 31 spline axles and oil, no brakes 59.5 kg (Strange alloy housing with Truetrac centre 23 kg, Housing 22 kg, axles 14.5 kg)
Rorym's BW M78 Skyline, no oil, open centre, brakes and axles 64 kg. (From this thread)

If you take 8 kg off the M78 Skyline for brakes and add 1 kg for oil that makes it weigh around 57 kg vs 59.5 for the alloy centre 9". Once you add the weight of a decent centre to the BW it will probably be heavier than 9" with an alloy centre.

If you a going to compare weights of diffs that need to have the same type of centre.

In my opinion the main advantage a BW M78 has over a 9" is you can fit a KAAZ. The KAAZ is not available for a 9".

Edited by ls2lxhatch, 25 November 2011 - 12:27 AM.



#17 claysummers

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Posted 10 October 2020 - 11:53 PM

Thanks for providing the figures mick. LSD vs open centre wouldn’t be more than a kilo I reckon, so seems to me BW=banjo+14%, 9”=banjo+41%. That is a significant increase in unsprung weight, more than equivalent to running light truck tyres on steel rims vs passenger tyres on alloy rims. So if the BW is up to the job then the weight saving is well justified.


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#18 mick_in_oz

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Posted 11 October 2020 - 07:31 PM

I read all the weight measurements as there being a small difference between a BW and a 9", and the 9" being lighter than the BW if using an Alloy Carrier, to me, unless you are really hung up on weight, what's a couple of Kg, really, what's 10Kg or so, or maybe I should say use a 9" with Alloy Carrier and be lighter than the BW...

 

Actually, the Alloy 9" mentioned was less than 10Kg heavier than the Banjo with open centre!



#19 claysummers

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Posted 11 October 2020 - 10:06 PM

Just that you’re not comparing like for like bu5 then I don’t suppose you can get an alloy carrier for banjo or BW. Does sound like a good thing. Anything you can do to lessen unsprung weight improves handling considerably, hence the performance benefit of alloy wheels and independent front and rear suspension. Jaguar IRS was a popular mod back in the day, fitted to many hot rods but also street cars, panel vans etc. I’d like to see someone put commodore IRS in an older car, but think I’ll stick with live axle banjo or BW. Sadly the Volvo Dana and Hilux diffs are hard to obtain in good cruising ratios unless you go to an overdrive.


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#20 yel327

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Posted 12 October 2020 - 08:53 AM

You can get Dana 44 gears at least as tall as 3.08. I remember looking at taller gears for my Overlander as it had a TH400 and needed taller gears. It had a 44 in the front and a 60 in the rear. Example:

https://www.yukongea...g & Pinion Sets

Which series Volvo too? You still see complete 240’s for a few hundred bucks.

Are we sure a Volvo is a Dana44? I thought they were a Dana 30 or similar?

Edited by yel327, 12 October 2020 - 09:00 AM.


#21 claysummers

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Posted 12 October 2020 - 09:04 AM

You can get them from the states I know but CBF when you can just pick up a BW complete off Gumtree for a couple hundred.

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#22 yel327

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Posted 12 October 2020 - 09:54 AM

Here is Dana30:

https://www.yukongea...g & Pinion Sets

But wasn’t the whole point an easy option? BW needs shortening, new axles, ends changed to suit brakes and then on a coil sprung car you end up with problems welding the UCA mounts onto cast iron. I would have thought the Volvo Dana in an old leaf sprung girl would be far easier, get it rebuilt with new gears and spring perches added. I know there are other issues like adapting the Volvo brakes and the pinion location, but I doubt you are going to get much change out of $2000 to mod a BW housing to suit and have new axles made.

Edited by yel327, 12 October 2020 - 10:00 AM.


#23 Heath

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Posted 12 October 2020 - 10:02 AM

There's a huge difference between a non-F100 type housing 9" with an alloy 3rd member and shit, compared to a full house old cast iron job.
And unsprung weight makes a huge difference.

Retaining Torana stud pattern is no concern with any diff conversion, as is your brake choice.
Borg Warner 78's from R31's etc. are not thin on the ground, I don't understand why this is even a conversation. It has certainly all been covered before, and the situation is the same.

A light 9" is considerably more expensive than a stocko BW78, a heavy 9" is probably about the same price.
Both are fine.

The hotted up Banjo's with TrueTrac's and 28 Spline axles seem like a good thing but I don't know about the durability of the bearing caps for the carrier. They may well be fine particularly if you aren't a punishing driver.



#24 davelh

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Posted 12 October 2020 - 10:28 AM

Thanks Heath, I appreciate your input. My comment about the Skyline diffs being thin may only relate to SA, as they don't come up very often, and people want (what i think is) stupid money for them. I contemplated the banjo/trutrac but it is still a bit of coin for a centre and new axles, may as well spend it in a conversion!

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