41 replies to this topic

[yel327]

Why wouldn’t you fit the fine spline spider gears and axles so suit, custom no doubt, if you’re spending $2k already though? In my mates case the early grey crash box is the weak component, but behind a stronger box the axles would be next weak point, followed by the crown wheel?


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Depends, if it was just a very clean and straight old car and the LSD was worn out. Finding a repairable used one and repairing it will cost about the same as a new Trutrac. If you changed to fine spline axles they'd be custom so that is another $1000 or thereabouts. If it was a HQ-WB or LH-LX Torana I agree, you'd just go and find standard relatively easy to obtain fine spline axles from a HZ-WB or UC and use the fine spine trutrac.

[Shiney005]

Dosnt seem to show an option for the differing gear ratios however? So one size tru trac case fits all ratios??

I see they have different ones for Dana.

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Why wouldn’t you fit the fine spline spider gears and axles so suit, custom no doubt, if you’re spending $2k already though? In my mates case the early grey crash box is the weak component, but behind a stronger box the axles would be next weak point, followed by the crown wheel?

I'm going with the 28 spline setup with 3.08. The only downside is that during motorsport events I have to remove the hubcaps, which will reveal the non OEM axles.

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[hanra]

Also, in the shed, I have complete diffs of all ratios in factory configuration  - I expect course or fine is irrelevant in this discussion?

( except maybe 3.08 that has a D/locker fitted, would need to check.)

 

Are there any key measurements I could take to put it to bed for ypou?

 

 

Thanks mate!!! Appreciate the offer. 

 

I think this image from Heath puts any doubt to bed. 

 

There is a difference in the Case where the crown wheel mounts to. Interesting that Harrop were not concerned with this? 

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[yel327]

I see they have different ones for Dana.

Screenshot 2023-10-26 071100.png

 

I'm going with the 28 spline setup with 3.08. The only downside is that during motorsport events I have to remove the hubcaps, which will reveal the non OEM axles.

Screenshot 2023-10-26 070824.png

 

All the Dana diffs are like that, 30, 35, 44, 60 etc. They use a different unit for GM 12-bolt too, I think its 3.73 upwards and 3.55 down. I plan on getting one of these for my Ram, it is an open rear axle and is a pain in wet weather from a standing start up hill. It's like $2500 fitted.

 

If you were going for 23 or 25 spline you'd probably get away with machining down a pair of 1-tonner axles and these look the same on the ends as the original L34 axles. From memory you cannot shorten them to LH-LX length with 28 splines though, only LC-LJ. I remember trying this in the 90's to make A9X axles (for A9X also machine the bearing collar to push the bearing in further and the flange OD to fit inside the discs).

Edited by yel327, 26 October 2023 - 09:57 AM.

[claysummers]

I’ve got 3.08 LSD here but a real bitsa. It was original when I bought it from Holdspares around 1988. I spun the hemispheres turning right onto a main road in front of traffic. It went bang and forced the carrier arms apart so that it had to be prised out of the housing with a long crow bar under the car. I bought another LSD cheap, unknown condition, gave all my bits to my mechanic at the time and he put together a replacement. Come to think must have only used the crown and pinion from the original. Long bolt flange still. Always had some whine. Few years later i busted the spider gears just being silly, so pulled out the case and replaced the spooders. More whine, but still going 50k miles later. But it slips.


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[hanra]

Ive hit up Harrop. See if they reply. 

[hanra]

Hi Brad,

Thanks for your E-Mail,

All of our Banjo TrueTrac Units are built to accommodate any Crown Wheel you decide to go for.

Unfortunately I do not know the answer about the GMH Factory Fine Spline axles, although you should be able to bring this up with a Diff Shop and they should be able to give you an answer.

The only modifications that you might have to make are to the Diff Housing itself.

We currently have one of these 23 Spline TrueTracs on the shelf.

They are priced at $2,015.20 INCL GST.

If you would like to go ahead and purchase one please provide me with your Best shipping and billing address and I will process an order for you.

I had also asked if the GMH Torana axles were indeed 23 spline. 

[Shiney005]

My 28 spline one was $1,480.

[hanra]

Wont be easy under Albanese.

[yel327]

Hi Brad,

Thanks for your E-Mail,

All of our Banjo TrueTrac Units are built to accommodate any Crown Wheel you decide to go for.

Unfortunately I do not know the answer about the GMH Factory Fine Spline axles, although you should be able to bring this up with a Diff Shop and they should be able to give you an answer.

The only modifications that you might have to make are to the Diff Housing itself.

We currently have one of these 23 Spline TrueTracs on the shelf.

They are priced at $2,015.20 INCL GST.

If you would like to go ahead and purchase one please provide me with your Best shipping and billing address and I will process an order for you.
 

I had also asked if the GMH Torana axles were indeed 23 spline. 

 

That isn't that bad. $1850 or so for the new Trutrac ex GST. A good used fine spline LSD to suit rebuild will probably cost you $1000 plus rebuild cost plus GST. Setting it all up in the case will cost the same whatever it is.

 

Yours will be 23 spline.

 

Have you confirmed for sure your case is a 3.36-3.90 unit? Your case is definitely a 2.78/3.08. Did the diff rebuilder use the actual LSD case you gave him with the 3.55 gears?

 

Note I used CASE for the banjo bit that bolts to the housing and CARRIER for the bit the crownwheel bolts to. Attached is the relevant page for the HT Engineering Technical Specs that shows the terminology. Shows you that the use of CARRIER as being integral with the Salisbury 10 and 12 bolt housings.

 

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[hanra]

The diff that was originally fitted to the car when I bought it was a 3.08 and was NON-LSD. 

 

I supplied the diff shop the NON-LSD Assy complete. Axle housing/Long Bolt Cast Iron Carrier/3.08 Gears/Non-LSD Case etc. 

 

I then also supplied them with a 3.55 LSD centre which consisted of a Cast Iron Carrier/3.55 Gears/LSD Case etc. 

 

They took the Long Bolt Cast Iron Carrier and fitted the 3.55 Gears along with the LSD Case to the Axle housing. 

[hanra]

Confusing when they mix up the terms....

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[yel327]

Confusing when they mix up the terms....

 

I get what you have now. That diagram you put up is the same as the Eng Tech Spec. It calls the carrier the bit that holds the pinion and the case the bit that holds the crownwheel. My text in the last post was confusing and when I read it back is arse about!

[claysummers]

Phew! You had me scratching my head there.


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[claysummers]

Ok. The 3.36 and 2.78 cases are nodular casting vs grey iron in the shorter ratios. But this is only talking about non-LSD.


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[yel327]

I think it is actually the LSD that were nodular as they were built by Borg Warner originally, and all V8 banjo were LSD initially. I think they were still LSD at the start of HT, at least the 2.78 examples were. At some stage GMH started to make them and also make 2.78 and 3.08 non-LSD but not sure when. The HK Eng Tech Specs states that both 2.78 and 3.08 will be made in non-LSD at some stage, but I’m not sure that occurred in HK. In fact the only situation where 3.08 was available in a HK 6cyl (186S M21) it was actually with a V8 LSD diff as it used a special tailshaft with a bigger uni joint, which sort of suggests there was only one spec for a 3.08 banjo and that was V8 LSD. By the time LC came around GMH must have been making them.

[hanra]

100kph on the GPS. 3000rpm. 110kph on my Speedo. 2659klm on the clock since resto.

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Edited by hanra, 28 October 2023 - 03:48 PM.