LSD differential heads up

[Dart77]

Are you going the powertrax? Are you changing the ratio?

I've only just bought the car and haven't driven it at all, except back from the seller's house. The factory LSD might be alright in it yet - he certainly babied it. Although he said he gave it "some" occasionally, but said he never did burnouts (which I specifically asked him about), as it was a work car and was using expensive tyres and was paranoid about wearing them out. The reason I'm not driving it yet is that I'm waiting for the auto to be serviced. He might have kept it in pristine condition but he wasn't mechanically minded. I'm pretty sure the trans has never been serviced in over 200,000km. Which is a worry for me. Plus he didn't even know the diff ratio or whether it was an LSD - I had to look those things up. He didn't even know if it had a dipstick in the engine bay for the trans ! And he's had it 15 years.

I spoke to the automotive place that has known the car since it was new in 2008 and he couldn't remember servicing the auto. I'm tempted to do it myself, have done plenty of Trimatics and TorqeFlites over the years. But I've only got jack stands and am a bit dubious about running the engine with an unfamiliar car on stands just yet. Plus I don't have anything yet to pump the ATF back in. I'll let the shop handle the first service and make sure I'm there to look at the old oil and inside the pan etc.

As for the diff... I like the 2.92 ratio, but would prefer what's in my VK which is a 3.08. I'm surprised that with 6 speeds and 2 Overdrives, that they used such a tall ratio! Wonder why? Economy? A 3.27 would make more sense to me. Did the wagons get the same ratio as sedans?

Will sus out the price of a new LSD centre. I think the diff guy mentioned around $2100 for the changeover for the PowerTrax. But he said for guys who bring in a whole diff which is broken, ie crown wheel and / or pinion, then it's around $4000 to rebuild it completely. This car's been dynoed at just under 340 hp at the rear wheels. This engine when stock is supposed to put out about 360hp (engine hp). So if the stock LSD is still good, that's not too much extra and I don't do burnouts or treat them hard like some guys.

 

[Dart77]

believe the harrop true trac is meant to be built better and hold up to more power than the Eaton version,
a few years ago I fitted an Eaton version to my old vx ss and was mint had no complaints with it perhaps the quality has gone down hill recently

Yeah I heard that too about the Harrop. The diff guy did mention them. But there was so much new information going into my brain that I couldn't keep track of everything he was saying.

 

[Dart77]

I'd say the LSD's were a bit poor since they fitted BW diffs (VK/VL) it's just cars had a lot less power back then, can't comment about earlier Commy models as I've never had a genuine one, just upgraded.

Maybe quality had gone down hill if they are been produced overseas now instead of in the US although they have never had a perfect reputation, seen plenty of threads across the internet talking about issues with Eaton true trac diffs been noisy.

I thought all the 1st Gen Comms had Borg Warner diffs since the VB? What were the HZ Kingswoods and WB utes using? The BW name changed to BTR Eng (BTR Engineering) after a while but they were the same unit, just a bit different in castings to accomodate various gear set changes. These diffs had cone style LSD units. Not sure when they went to the clutch type - maybe when they started using the IRS? No idea really just guessing!

As for quality - it's the same everywhere for virtually everything. The huge populations needing stuff means much more quantities being produced and the corporate lust for money means they can get away with many more failures and complaints and still make their profits.

 

[Dart77]

... have had a few issues with the Harrop ones too.

I think the Harrop ones are still made in the USA? Not sure though. There'd be a lot of various stuff being made in Mexico. They have tons of automotive machinery being made there, lots of types of engines, transmissions, A.M. valves, Eagle cranks etc etc

 

[Dart77]

Had 2 Eatons now in VY series cars.
The first was a bit clunky but it was behind a cranky manual. Still performed mint.
Current one in the Monaro is a lot better.
Powertrax look like a torsen style which is what the Eaton/Harrop units are. They will still single up if they get super low traction on one side or lift a wheel.
Look at a Wavetrac in VE and later if you want something better but you will pay for it.

Thanks for that - nothing beats experience. I think the Wavetrac are another $650 on top of the PowerTrax and Eaton. As with almost everything - it's what you pay for is what you get. They've got their manufacturing costs/profits down to cents now.

 

[losh1971]

I've heard the Wavetrack is good for 1000hp maybe more. Need to way up cost verses need. Think I paid $1500 for the Kaaz centre so not cheap. I'd have to check my invoice to be sure on what I paid. Kaaz is more like an LSD than a Tru Trac is in that it's always locked to some extent. Then when you load it up it locks up harder. More maintenance with a Kaaz though as they require 15k oil changes.

 

[losh1971]

Whatever you choose, don't go for the Chinese Tru Trac that some people buy they are right junk according to Steve Hillman but people buy them because of the price.

Gears is something else to factor. The best gears are factory but shortest is 3.7 and they are the most expensive. The only other gears worth considering are Motive. The rest are junk but you have probably already been told that.

If you have a budget for it get your gears polished. Not sure if your diff builder has the machine as very few diff builders in the country have one. But my diff builder polishes 100s of sets for other builders and is happy to send them across the border. It is definitely worth getting them polished if you can. Also don't mistake gear polishing as lapping on a lapping machine its a totally different process.

 

[Immortality]

I think the Harrop ones are still made in the USA? Not sure though. There'd be a lot of various stuff being made in Mexico. They have tons of automotive machinery being made there, lots of types of engines, transmissions, A.M. valves, Eagle cranks etc etc

Harrop are made in Aussie, or rather the casings are made in Aussie to suit our diffs, the internal worm drive gears are genuine Eaton as I understand it.

I thought all the 1st Gen Comms had Borg Warner diffs since the VB? What were the HZ Kingswoods and WB utes using? The BW name changed to BTR Eng (BTR Engineering) after a while but they were the same unit, just a bit different in castings to accomodate various gear set changes. These diffs had cone style LSD units. Not sure when they went to the clutch type - maybe when they started using the IRS? No idea really just guessing!

As for quality - it's the same everywhere for virtually everything. The huge populations needing stuff means much more quantities being produced and the corporate lust for money means they can get away with many more failures and complaints and still make their profits.

First gen Commodores VB-VK used the Salisbury diffs, VK was the change over model where they first fitted the BW diffs. Holden just had them set up loose so they slip. Built properly they are a lot better but still limited by the design.

 

[Dart77]

First gen Commodores VB-VK used the Salisbury diffs, VK was the change over model where they first fitted the BW diffs. Holden just had them set up loose so they slip. Built properly they are a lot better but still limited by the design.

Ta for the info. My VK (Apr 1984) is the first iteration (pop-up door locks, 1920's style chrome roof-rack etc) and it's got the Borgy 3.08 non LSD. Must have been one of the first ones to get it then.

 

[lmoengnr]

Harrop are made in Aussie, or rather the casings are made in Aussie to suit our diffs, the internal worm drive gears are genuine Eaton as I understand it.



First gen Commodores VB-VK used the Salisbury diffs, VK was the change over model where they first fitted the BW diffs. Holden just had them set up loose so they slip. Built properly they are a lot better but still limited by the design.

Harrop's centre and pinions are made in house, a billet centre, and the pinions are larger and more of them than the Eaton design.