Banjo/Commodore LSD centre

Benjamin · backyard mechanic Joined: 05 Oct 2001 Posts: 525

I am seriously considering an early Commodore or Banjo LSD centre swap, as I may just be able to source a donor. Does anyone know anything regarding putting one of these suckers in?

I called Castlemaine Rod Shop and Rod put me onto a mob in Geelong. They haven't seen an LSD Gemini diff in years but they told me the easiest option is a centre swap.

I need traction, I am sick of this spin-the-inside-wheel-around-corners-and-get-no-fuqqin-grip caper.

I wonder how the hell some of you guys with more power cope!

Thanx Smile

Pete · backyard mechanic Joined: 05 Oct 2001 Posts: 502

what about a piaza lsd? quicker and i dare say cheaper option. from memory there was someone selling one recently.

Benjamin · backyard mechanic Joined: 05 Oct 2001 Posts: 525

Unsure about cost, that's why I thought this option would work out ok if I could find one. Chances are probably slim but who knows.

There are a few things working against the Piazza though aren't there? Firstly the track is wider, so I must get the diff shortened, then there is the matter of what I do with the torque tube, or is that the same as a Gemini? The third is a matter of where the hell I find one of those in Central Vic (I could probably find one in Melbourne but for how much?)

Are they disc rear end on those things? If so, bonus, but then I must mate up some rear calipers.

Have I just made things more complicated that they should be or are things not simple?

I have a speare late model diff left from my TX, which I was considering experimenting with using the LSD centre. I was also told Commodore rear axles will fit if shortened, and if so, I would probably use them and work out a way to have 5stud all round and choose some better wheels and brakes later on.

Thanx Pete.
I think I need help Smile

gemie chick · tinkerer Joined: 06 Oct 2001 Posts: 94

hey ben its greg... just get some fatter tyres man Smile

Benjamin · backyard mechanic Joined: 05 Oct 2001 Posts: 525

Hey Mr Gregory!
You goonna send my Melways up? I will email Deb the address.

Fat tyres, yeah, lowered suspension, yeah. Still wouldn't help me without LSD. The green one wasn't as bad lowered, still not good for drifting Sad

TXcoupe · petrol head Joined: 05 Oct 2001 Posts: 1675

if you have the salisbury diff (td onwards) i would be looking for a UC torana lsd centre as the diff codes are the same ( thanks to a mate in bunbury for letting me work on her car :0) and you could even run the axles and centre...

Racegem · backyard mechanic Joined: 30 Jan 2002 Posts: 987

That would be interesting to see if the centre does go in, cause I have a book telling me the UC had 2.78, 3.08, 3.36 and 3.90 with LSD optional. Whole diff's approx. 80mm wider though, but the centre might fit.

Food for thought....

Yonnee.

TXcoupe · petrol head Joined: 05 Oct 2001 Posts: 1675

yeah on the compliance plate the code said GU8 so its the same diff just shorter...

Racegem · backyard mechanic Joined: 30 Jan 2002 Posts: 987

But I think the code only tells you the ratio; A commodore with GU7 has 2.78, GU4 is a 3.08 etc., but it doesn't mean they have different diffs. GU8 would be 3.90 as both had this ratio.
Then again, my "bible" list both cars as having the "Holden small salisbury" so the centres might be interchangeable. Imagine 'croozin' with top gear fifth and 2.78 rear, the thing would be barely idling. lol

Yonnee.

Benjamin · backyard mechanic Joined: 05 Oct 2001 Posts: 525

Ok, all sounds good, but one question is bugging me. I don't know a hell of a lot about diffs, I have yet to pull one apart and see for myself, but I have a little knowledge.

The final ratio should be as close if not the same as it currently is, so what happens with the crownwheel? Is it a matter of unbolting the crownwheel from the Gemini centre and bolting that to the donor centre? Therefore the ratio of the donor diff is irrelevant if I can swap?

Thanx guys Smile

Racegem · backyard mechanic Joined: 30 Jan 2002 Posts: 987

I'm fairly sure to change ratios, you have to change the pinion gear as well, which, with the torque tube is not just an easy swap, if it does swap at all.
The final ratio is what you want it to be. Low numbers give you lower highway revs and good top end speed, but not good off the mark. Higher numbers give you good launch, but sacrifice top speed.
If you found an LSD centre with 3.9 ratio, you'd just remove the bearing caps, swap centres, and bolt the new centre in. Sounds too good to be true, and without having done it or spoken to anyone that has or has tried, it probably is.

Yonnee.

Ben Wight · backyard mechanic Joined: 04 Oct 2001 Posts: 946

Yeah, to change ratio, you need a matching pinion and crown wheel. I have been trying to swap an LSD centre into a spare diff, and the guy doing it says that he will simply bolt my crown wheel to this new centre.

In that repect, you dont have to keep the same ratio, you can use a different crown and pinion, but then you have the problem of fitting the torque tune onto a different pinion.

Ben Wight

Trublu · newbie Joined: 12 Feb 2002 Posts: 7

Hey guys i have a TG Gemini wich i would like to make into a LSD diff i know i can get a commodore LSD but will i blow the axles in the diff or will it be ok i dont really want to go 5 stud by changing the axles..

thanks guys