LSD, A possible alternative.

Rodeobob · Post by **Rodeobob** » Sun Aug 07, 2005 5:22 pm

Ive got my suspicions that the KB Rodeo/Shuttle/Jackaroo centres are the same as the piazza one. In LSD form if you can find a Jackaroo one possibly in the Rodeo too. I dont think they offered LSD in the shuttle.

If someone can check the Piazza manual against this data for me.

Banjo type, semi floating.
Hypoid gear.
Bevel gears 2, Pinions 2 (open wheeler)
LSD option, 4 pinion dual disc. (i think thats meant to be dual pinion 4 disc looking at the pics.)
194mm crownwheel diameter.
Backlash 0.13-0.18mm.
Pinion preload, Colapsible spacer.
Side bearing preload method, shim.

The ratios ive got are 4.555(41/9). 4.1(41/10) for Jackaroo and Rodeo (81 models) it doesnt state what is in what. 4.777(43/9) for the shuttle auto and diesel and 4.555 for the manual petrol. It also lists a 5.158 for the real early shuttle but i doubt you find one here in australia. The shuttle books cover all models.
I rekon 43/10 would give you 3.9 same as the Piazza.

Ive got the TF Rodeo books here, it lists the 194mm diff too, but only for the 2.3L powered few at a guess, it doesnt actualy state what is in what. The actual diff used in the 2.6L TF is 220mm, so these would be no good. The manual covers africa and the like where they got the 1.6L 4ZA1 motor, mainly thats why its in the book id say. It gives a bit more info on the diff. This covers both sizes.
Axle tube diameter, outside, 75mm.
Thickness 4.5mm.

What none of the books give me is the number of splines and diameter of the axles which is the info thats needed.

If your going to hunt for an LSD centre id look in the rear of a 4x4 or a diesel 2x4 KB Rodeo. A Jackaroo would be the best bet and id have to say looking in a diesel one would up your chances more.

I wanted to keep this under my hat till i was sure.

Ive got a Jackaroo LSD centre lined up for my KB20. When i got it here i was going to rip the single wheeler out of my auto piazza and have a look.

Cheers. Bob.

P.S. dont tell the Gemini guys about this or they will want piazza diffs to make fit and pinch all the LSD centres.

GeminiCoupe · Post by **GeminiCoupe** » Mon Aug 08, 2005 12:15 am

Just incase you missed it...

Bugle wrote:Bob yer it's the same dimensions. LSD is 2 pinion, gears are 43/11. No good to Gemini owners they don't run Jap rear ends and the diesels that do use the 8-bolt diff center. Didn't measure the axle diameters but they're 17 spline if i remember correctly.

Bear with me hear as im abit slow when it comes to Piazza stuff. From what ive gathered so far both the openwheel diff and LSD diff share the same housings? And the Jackaroo Diesels SHOULD have an LSD which bolts into the Piazza carrier? Which Jackaroos are we talking bout here - the 80's ones with the G200 and 4ZD1 in them?

Are you sure the Piazza diff is 17 spline? That sounds abit low seeing as i think the gemini had 25spline from memory. Seems odd that Isuzu would put more splines in the mundane shopping trolley.

Whats the weak link in the Piazza diff everyone talks about?

Nick-

Bugle · Post by **Bugle** » Mon Aug 08, 2005 12:59 am

Yer i've only seen the shuttle/rodeo one the housings from the outside looked exactly the same as the Piazza one. So if you wanted you could probably change the gear set to 4.1 or one of those other silly ones, but i'd rather 3.9. Don't need to worry about the LSD we've already got them

How common are LSD's in jackaroos and rodeos bob?

Yeah pretty certain it was 17. Definitely very coarse. Pretty chunky axles though don't think theyd break.
The weak point is probably just that it's 2 pinion. For some strange reason the torque tube Piazzas have a 4 pinion LSD. They went cheap on the new setup.

Rodeobob · Post by **Rodeobob** » Mon Aug 08, 2005 1:48 am

Bugle wrote: Yer i've only seen the shuttle/rodeo one the housings from the outside looked exactly the same as the Piazza one. So if you wanted you could probably change the gear set to 4.1 or one of those other silly ones, but i'd rather 3.9. Don't need to worry about the LSD we've already got them
How common are LSD's in jackaroos and rodeos bob?

Not that common but common enough in the Jack. More so in the Diesel ones id imagine. Rodeo im not sure, id say 4x4 diesel too. Possibly 4x2 diesel. I know they did offer it in the bigger diff in the 4x2 turbo diesel in the TF.
If you had an auto car, chances are youd be looking for one bugle. lol.
Swap ratios if you are that way inclined, its all about the magic LSD hat. A 4.555 would help a quarter mile time one would think.

Bugle wrote: Yeah pretty certain it was 17. Definitely very coarse. Pretty chunky axles though don't think theyd break.
The weak point is probably just that it's 2 pinion. For some strange reason the torque tube Piazzas have a 4 pinion LSD. They went cheap on the new setup.

I dont know that its that they went cheap, id say they just went with one they already made.

GeminiCoupe wrote:Are you sure the Piazza diff is 17 spline? That sounds abit low seeing as i think the gemini had 25spline from memory. Seems odd that Isuzu would put more splines in the mundane shopping trolley.

Gemini 25 spline, Remember that it was an australian made sailsbury, Holden were never much good at making diffs. lol.
cant say i know too much about the engineering in diffs, but i wouldnt imagine that splines are a direct relation to strength. More splines just allows more face to hang on to. I suppose it does have some engineering benifits, it means the force is spread over more spline face, which creates its own drawbacks. Less beef in the spline, more force with which to twist the end off the axle. I had HZ fine spline axles and centre(banjo) i put into a HQ, the splines were pretty twisted. Snapped an axle in the end. Funny coz it spent all its life in a 202 3 on the tree granpa station wagon. I never had a drama with the coarse spline ones. Just used to chew out pinion bearings.

GeminiCoupe wrote:From what ive gathered so far both the openwheel diff and LSD diff share the same housings? And the Jackaroo Diesels SHOULD have an LSD which bolts into the Piazza carrier? Which Jackaroos are we talking bout here - the 80's ones with the G200 and 4ZD1 in them?

Yeah the whole carrier LSD or open centre will drop into the other housing. In the case of the Jackeroo/Rodeo job it will be as long as the axles are right.

Im in no way sure what is in what. Ive got a set of manuals here that cover the Rodeo for 1981 and it comes with a supplement to cover the Jackeroo of the same year. Ive got the manual set to cover the shuttle from start to finish. And the full set for the TF rodeo. Its just got the info for how to fix whatever was fitted.

I can say that the TF rodeo is out. Its possible that the Jackaroo got the bigger diffs first. They got the V6 before the Rodeo did.
G200 Jackaroo would be ok, ditto with the N/A2.3L diesel. I cant say with the 2.3L and TD2.3L Jackaroos, i think they started in 85. so 81 to 84 should be the right job. Rodeo 81 to 87 KB. Ive got a bit of a handle on the KB/20/40/28/48etc and what the numbers mean, as for the Jackeroo all i know is UBS and they go right thru 81-98 or so. Take a tape measure. lol.

GeminiCoupe wrote:Whats the weak link in the Piazza diff everyone talks about?

Old age, heaps of miles, extra grunt and driving it like you hate it. One or all of the previous. I dont think its particualraly weak in any aspect, it just not bullet proof. Theres no way it would be as close to its limit as a Banjo diff in a torana.

Cheers. Bob.

GeminiCoupe · Post by **GeminiCoupe** » Mon Aug 08, 2005 10:24 am

Bugle wrote:Don't need to worry about the LSD we've already got them

Yeah, but the way i drive its only a matter of time before something either wears or tears - preferably the first. Its good knowing theres a local replacement - makes hunting down new clutches abit easier. Definately stay with the 3.89 though.

Rodeobob wrote:cant say i know too much about the engineering in diffs, but i wouldnt imagine that splines are a direct relation to strength. More splines just allows more face to hang on to. I suppose it does have some engineering benifits, it means the force is spread over more spline face, which creates its own drawbacks

Its pretty much exactly that - the more splines the more evenly the torque is distributed, meaning less chance of snapping gears/cogs/teeth off the splined end. The gemini 25spline diff is a pretty tough thing - ive never managed to blow one, neither has the old man. They take severe punishment - the one in our old TE was used as a commercial vehicle and bush basher - at the same time. I remember once the old man swinging doughies on a mates block with the boot and back seat full of wood blocks...tuff little thing that car was.

If the Rodeo/Jackaroo centre is, say 25 spline, yet still fits in the housing, then its just a matter of getting axles made up for it [around the $500 mark]. It still makes it a viable conversion for a gemini as you have to shorten the diff/axles anyway....

Nick-

Bugle · Post by **Bugle** » Mon Aug 08, 2005 1:14 pm

Jackaroo is the same spline as the Piazza. There was one at the wreckers with the diff removed but axles still there so I pulled one out and checked. Should've checked that with the shuttle i saw the other week someone had done the same thing.
When I had my axles out they showed no signs of any wear or twisting and i'm sure my car has been thrashed before I owned it. Probably nothing to worry about..

Yeah it's possible the Rodeo/Jackroo uses tighter clutches too which could be good.

Rodeobob · Post by **Rodeobob** » Mon Aug 08, 2005 3:12 pm

If the Jackaroo is the same as the Piazza the Rodeo and the Shuttle will be too. The diffs are the same track in the commercials.

GeminiCoupe · Post by **GeminiCoupe** » Mon Aug 08, 2005 8:37 pm

Hang on, i just realised something...fuck me dead im slow.

How much wider is the Piazza's track then the Gemini's? 10mm each side? This could be overcome by wheel offset right? From memory the Gemini offset was 35....because the piazza diff is 10mm longer each side you subtract 10 from the wheel offset right? That means the only mods i need to do to fit the LSD is re-weld the shock mounts [easy shit] and make up the 4links....

BOB!

Nick-

Bugle · Post by **Bugle** » Mon Aug 08, 2005 8:47 pm

I think it was closer to 25mm on each side.
Have to sort out a panhard rod mount for the axle too it's on the opposide side with the Piazza.

edit: Piazza rear track - 1380, TG Gemini - 1325

Rodeobob · Post by **Rodeobob** » Wed Aug 10, 2005 3:40 am

Bugle and i already had this discussion in Brendans hijaked thread.http://www.holdenpiazza.com/forum/viewt ... 9&start=30

At least you proved your worth, 2 + 2 does equal four. lol.

Its actually a mod id advise against. Its not a good thing to have the rear track any where near wider than the front. Bad understeer will result. Wheel offset will help but finding a spare that will do on both ends will be a bitch.

Id only look at it on a gem where a brake rearangement/upgrade has increased your front track by the similar 55mm.

I suppose the other thing is, The track measurements you quoted Bugle, is it stated where they are measured from??? sometimes track is mounting face to mounting face other times its measured from tread centre to tread center. Not much issue on a Piazza or a gem i would imagine but worth mentioning.

Id still recommend you put your money into a VL-VR diff. Go the 5 stud too and match it fith a front brake upgrade. Id prefer a falcon job to get rid of the commodore poxy hand brake.

The other thing is the Piazza rear brakes. They are vented discs and they a freakin huge. They are bigger than the front discs.

Bob

ozzie · Post by **ozzie** » Sun Sep 04, 2005 2:39 pm

have a read of this man
http://holdenpiazza.com/forum/viewtopic.php?t=216