No ford 9 inch, what do you recomend

mantis-bec · #1 (**permalink**) 03-13-2007, 07:15 AM

Having trouble trying to work out what diff to put in my rolling chassis. I don't want to run a ford 9 inch or run anything that is IRS. Can anyone tell me what the easiest diff to put in my chassis would be. I would prefer not to get an engineer to cut and join. I would rather hear that for eg, a torana, diff is short and works well, or maybe even a vn commodore, I know I am talking Holden I have just heard they are normally a little narrower than the usual ford. I may have heard wrong but any input would help, please.

sambo · #2 (**permalink**) 03-13-2007, 07:23 AM

You might need to provide more information about this rolling chassis mate. Eg, is it from a kit manufacturer or home made, any provisions for diff/suspension mounting points, etc.

simon clemens · #3 (**permalink**) 03-13-2007, 07:42 AM

I think that the good old B/W ford diff is plenty, Its what I have in mine, 28 spline, 4 pinion LSD, 3.73 diff ratio.
yeh I had it shortend to suit my application, cost me $100 for the 2nd hand diff (complete) EA falcon Disc. To shorten with new 28 spline axles, all brackets welded to suit custom suspention, tailshaft made & balanced all for $1800 total!!!

You can have it all done and fitted to your chassis for under 2k !!!

Some people put a hell of alot of street HP through these diff's without any problems. Another person I know has an un-cut B/W in his cobra, but the rim selection was not able to have any dish, I like the deep dished type rims, thats why I had mine shortened.

Hope this is of use to you.....

Simmo....

barabar · #4 (**permalink**) 03-13-2007, 10:05 AM

Here's a thought,
That 9 " can handle 900 hp +or- depending on build, also you can change the ring and pinion in the time it takes to take a healthy **** and won't break the bank, plus a high school dropout can work on them.
If you get into some of those exotic rear ends you have to be a Rhodes Scholar to work on them, not to metion special tools and a pocket book that would let you shop at BJ's auction.
Think About It!

boxhead · #5 (**permalink**) 03-13-2007, 05:45 PM

I know the hotrod guys use the Hilux 2wd diffs in the lesser powered vehicles.

I have heard of them fitted behind stock small block V8's with no problems of failure when driven like a normal car.

Shelby400 · #6 (**permalink**) 03-13-2007, 08:43 PM

My Homebush uses the Torana rear end setup. I have proved on two occassions that a Torana diff is nearly as good as a tooth pick would be for the rear end.

Now I use a slightly modified Commodore VN diff. They are not as tough as a Ford 9" but they are half the weight.
Its a vast improvement on the Torana.

Brett

cameron02 · #7 (**permalink**) 03-15-2007, 06:08 AM

As mentioned, it would be beneficial for you to state what kit you are building plus what sort of horse power you intend on running, also wether you want limited slip or not. A small diff might be OK if you are not running much HP and are not intending on spinning the wheels.

Hey Brett,

was your Torana diff a fine splineand was it LSD or single spinner?

I'm interested because I'm running a Torana diff.

Shelby400 · #8 (**permalink**) 03-15-2007, 04:27 PM

Hi Cameron

The first one was a course spline single spinner. The second was a fine spline LSD.

Both had the same problem of disintegrating carriers.
Snapped an axle once as well.

So far the BW78 from the Commodore has taken some punishment.

I highly advise you look at something a bit stronger than the Torana diff.

Brett

Aussie Mike · #9 (**permalink**) 03-15-2007, 05:42 PM

I used to destroy diffs in my XU1 Torana with a warmed up 6 cylinder. They are not the best choice for a Cobra. Brett is right, go for the later Commodore BTR diff. It will be more than strong enough and you will get disc brakes standard.

The other option if you aren't in a hurry is to go to swap meets and keep an eye on the Trading post. Every now and then I see Ford 9" diffs that have been converted for Torana going for reasonable money.

The 9" is a big heavy diff though and probably over kill for a 5.0L equipped car.

Cheers

mantis-bec · #10 (**permalink**) 03-21-2007, 07:12 AM

I seem to be turned towards the Commodore diff, probably a VN as I see they can be picked up cheep and dont run the IRS (Which i have on my VS and I hate it).
Is the Commodore diff the same with as the cobra's require, or will it need to be shortened.
Thanks for all the input.
Nathan

sambo · #11 (**permalink**) 03-15-2007, 05:53 PM

Mike (or anyone else) do you have an opinion on putting an R32 Skyline diff behind the new L76? The Skyline was around 200kw whereas the L76 is about 260kw and 510nm. All that torque has me a little worried, especially since I will probably go a bigger cam down the track.

Aussie Mike · #12 (**permalink**) 03-15-2007, 06:06 PM

I reckon it'll be fine Sambo. Many of those tuned up skylines are making a awful lot of power and torque. Plus the skyline is significantly heavier than a Cobra.

I believe the internals of the Skyline diff are the same as the Commodore i.e made by BTR (who I think are now owned by Dana). Several people have told me the diff gears are interchangable between the two.

Cheers

sambo · #13 (**permalink**) 03-15-2007, 07:35 PM

That's good news because I'm being quoted around $1000 for the 200SX (S15) helical diff centre and that's second hand. It's a much better centre than the R32 stock item. So it sounds like I have a few more options if BTR are in the same market.

Aussie Mike · #14 (**permalink**) 03-15-2007, 08:21 PM

It's becoming quite a common conversion in the US to drop an LS1 into an S15 and S15 Nissans. These guys are not reporting any diff problems.

S14 LS1 Conversion

Cheers

cameron02 · #15 (**permalink**) 03-15-2007, 10:17 PM

Thanks Brett, what model commodore's have the BTR diff?
Thanks Mike.

sambo · #16 (**permalink**) 03-15-2007, 10:25 PM

Quote:

Originally Posted by Aussie Mike

It's becoming quite a common conversion in the US to drop an LS1 into an S15 and S15 Nissans.

Crikey, I used to own an S15 and putting the full 147kw to the ground was difficult enough. Bigger turbo/intercooler conversions required camber kits in the rear and other measures to stop excessive axle tramp due to squatting. A 500nm V8 is unimaginable.

Aussie Mike · #17 (**permalink**) 03-15-2007, 10:39 PM

The earlier cars used Borg Warner diffs but I think that company was torn apart and the gearbox side of things taken by Tremec and the diffs going to BTR. VN, VP, VR or VS all had live axles available. After that they are nearly all IRS. Boxhead would certainly be the man to ask on the Holden diffs.

Cheers

cameron02 · #18 (**permalink**) 03-16-2007, 04:31 AM

OK......................

what's the difference between live axles and IRS

boxhead · #19 (**permalink**) 03-15-2007, 10:24 PM

I can confirm for you guys that when ordering warranty diffs through Holden it is all done through Dana.
And these are the BTR diffs.

snaken · #20 (**permalink**) 03-22-2007, 04:56 AM

I am running a VN commodore BTR diff with a Torana setup in a Homebush kit, on my third ratio looking for more speed and pull out of courners, started with 3.08 went to 3.45 and now running 3.93. The 3.93 is a skyline crown and pinion, just need bushes to make the bolts fit snug. I have had these three ratios in 6 years ?????

Motor makes about 350 HP or 370 KW ( photo attached) and every time I change the ratio the bearings are f...ed, but never had a problem while driving.

I am running synthetic diff oil.
This car is mainly driven at maximum revs on weekends at the track. The diff is stronger than the gearbox ( broke one of those) the adjustable upper arms (photo attached) as I broke both of those the other weekend getting in some burnout practice.

I would recommend the BTR diff ( VN) the most suitable and cheapest.
Good luck
Snaken