r154 gearbox to Commodore Vr ss diff

[GriZZly]

im trying to figure out a nice combination that will give me some decent ratios for a 1uz conversion im planning.. from everything ive read the r154 gearbox seems like the obvious choice but the rear dif ratio from a jza/ma 70 is to high.. these commodore diffs have a 3.08 ratio which works out nicely but im worried about 2 things. Will it take the power and what is required in getting it to matchup to the tailshaft..

has anyone had any experience with this? or should i just dig deep and buy a trd rear dif replacement for a jza70?

ideas would be great.. thanks

[whatthe?]

What makes you say that the MA70 diff ratio is too high? The turbo version came with an R154 after all...

[Grega]

depends on how much power you're going to make for one, and, what sort of diff is in the VR SS - is it IRS or Live Axle? If live, and LSD, you will be OK. If not LSD, then find an LSD type. If IRS then you should be OK also.

it really depends on how much power you're going to make. the vr ss had 165kw, with the 1uz having a bit more than that you should be ok

there are a few different ratios available for the live axle borg warner diffs in the commodores, 3.04, 3.45, 4.1 spring to mind but not sure about the IRS components tho.

[WDE_BDY]

What car you putting it in? VR live axle is pretty much the same as EA Falcon onwards (the EA diff I had was a 3.27 but crownwheel and pinion should swap over). Will give you Supra 5 stud pattern as well. I know VN V8's run the same axles spline as the 6 cylinder EA Falcons (most of which are LSD), we have swapped one into a VN V8 wagon housing with VN axles. Also the EA uses a single piece alloy driveshaft, just need to get it cut down and the R154 yoke grafted on.
If its going into a car with an IRS rear end already, you are in for a lot of work to put a different centre in.

Callum

[kingmick]

im trying to figure out a nice combination that will give me some decent ratios for a 1uz conversion im planning.. from everything ive read the r154 gearbox seems like the obvious choice but the rear dif ratio from a jza/ma 70 is to high.. these commodore diffs have a 3.08 ratio which works out nicely but im worried about 2 things. Will it take the power and what is required in getting it to matchup to the tailshaft..

has anyone had any experience with this? or should i just dig deep and buy a trd rear dif replacement for a jza70?

ideas would be great.. thanks

dig deep and get a cussco, trd etc diff!
It will cost a lot less and handle the 1uz no prob!

Yes the vr diff can handle it with ease aswell! i have one here that has handled 700hp+ at the wheels for 12k kms so far and its been given a hiding.

[GriZZly]

whatthe?: i cant remember exactly but i think the jza70 with the 7mgte came with a 3.7 or so final drive for the rear diff.. the vr ss is auto and for that reason has a lower number

grega: im hoping to make 250-300rwkw and yes it has irs and an lsd

wdebdy: at this stage i plan for it to go into preferably a ke20 or maybe a ke30 or55. also dont ur comments contradict themselves? you say u simply have the driveshaft cut down.. but if its an irs setup its alot of work

kingmick: what sorta price are we talking for a trd or cusco diff replacement, i cant believe itd be cheaper than a commodore rear dif as theyre available everywhere

thanks for the responses guys

[kingmick]

they would be around $1200. its not just the diff cost, its the setting it up and doing the tailshaft! be a fair bit more.

[WDE_BDY]

wdebdy: at this stage i plan for it to go into preferably a ke20 or maybe a ke30 or55. also dont ur comments contradict themselves? you say u simply have the driveshaft cut down.. but if its an irs setup its alot of work

Driveshaft, not shaftS. EA is a live axle rear end, but runs a single piece driveshaft between diff and gearbox. The live axle Commodore runs a 2 piece driveshaft so you then need to make a single piece shaft with the Supra front yoke and Commodore rear. If use the Falcon drivershaft its single piece so only needs one end changing. One advantage of the Borg Warner diff (which both the Commodore and Falcon are) is they run different length axles, 95mm shorter on one side. So can shorten both sides of the diff housing 95mm each and run a short shaft in the long side, then you only need to get one long axle shortened by 190mm. This brings the diff down from 1560mm ish to 1370mm ish, very close to the width you need. Whether you prefer Commodore or Falcon stud pattern will depend on your front suspension, either way you can get matching rear axles so won't need to restud them saving more money.
I would not recommend converting a KE20/30/55 to IRS, the costs far outweigh any benefits and you will have trouble finding one narrow enough. You do not want to pay to narrow an IRS. Stick to a live axle leaf spring rear, you can get them to handle quite well for much cheaper.

Callum

[WiLo]

whatthe?: i cant remember exactly but i think the jza70 with the 7mgte came with a 3.7 or so final drive for the rear diff.. the vr ss is auto and for that reason has a lower number

its a little bit OT i know but anyway
wouldnt a jza70 have a 1JZ-GTE in it? i was under the impression that JZA was if the engine was a JZ series block, and MA was for the 7M-GE/TE?

[GriZZly]

yeh sorry ur right

i was referring to the ma70

[Grega]

i'd stay away from the falcon driveshafts. were they not rumoured to not able to be driven over 180kmh (thats if you intend on doing this speed) as they had issues. i seem to remember this from a long time ago...

you can also get a kaaz replacement LSD for the inside of the borg warner (78 series i think is the diff code)

callum - good info there on the shaft sizes man. rep up.

[WDE_BDY]

Thats a good point about the driveshaft Grega, I very very vaguely remember hearing something about that years ago. Will have to look at something else for my mates car.

Callum

[mrshin]

If you're putting the engine into a Commodore, then use the Bogwarmer diff, otherwise don't bother converting it to fit another car. There are plenty of ratios, down to 4.1, available, and the diff itself will take it, although there are always noisy and clunky. The stock LSDs, however, are utter crap. You can get a KAAZ drop in replacement for it if you wish, although you'll still have the noisy/clunky gearset.

The Falcon driveshafts were aluminium, and were limited to 180km/h, except on the XR's where they had a steel shaft and no speed limiter.

[mrshin]

Just read your other post a bit more closely... for a Corolla conversion, don't bother with the Bogwarmer diff, and especially not the Commodore IRS. Why pick the worst possible rear suspension for your car, and then have to shrink it massively to make it fit?

Getting tailshafts made is no problem, as for doing an IRS diff conversion, I'm attempting this in the next few weeks myself, so it'd be better I comment then with actual experience rather than theorise about it!

[GriZZly]

let me know how you go mr shin.. what sort of car is it going into?

at this stage the conversion is just in the planning process and im picking up pieces i KNOW i will require the rest is left to speculation and ideas and dreams maybe?

the reason i picked the vr ss is it has a nice final drive ratio and quite cheap compared to getting a jza rear diff and buying a lower final drive..

i hadnt really though much about suspension but cant the axles just be shortened to slim the width of the whole thing?....