VR Ute

[immortality]

That's a interesting failure!

[vlad01]

Got any close ups of the breakage with the oil and gunk cleaned off? Can't tell for sure, but might be some metallurgical issues there going off that pic.

[brindo]

Thanks to a kind sole on this forum, I was given a ute diff for free to get us out of strife. Was an open centre so no LSD, but 3.08:1 ratio with the shot peened gears. Had a heap of play on the pinion so bought a full set of bearings to rebuild it.
And bought one of the Chinese copies of the Chinese copy Tru Tracs for $266 delivered. I could well be back on here weeping in a few months time cause it failed, but it looks no different to the one I put in the one tonner.

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I bought another set of the Yukon SK SS35 carrier shim kits but got messed around with shipping. But in my stash of carrier shims managed to get it all set up OK with only one shim needing around 0.004” taken off it and a bit of dressing on the glass plate. Also machined up a solid pinion spacer out of an old SS bolt. The end of the pinion ended up needing 0.070” taken off it, whereas in the M78 diffs the pinions still have clearance.
Anyway its in and running fine for now. Haven’t driven it very far but so far its quiet. That being said, I certainly wouldn't be looking to me for diff building advice. Traction should be much improved, no more single peggers.
Had a discussion on hard decel. See if this one will last.

[vlad01]

I think these units might be the same ones Mace sell? I could be wrong, I heard the clones are quite good from other's experiences.

Is the decel in regards to breaking the helical gears in them?

[brindo]

Not sure. The first one I bought years ago was from Supa F Spares for $600, which was a Chinese copy of the Tru Trac. They no longer sell them but they had good reviews.

What I bought just recently and what Mace sell could be one and the same, but the price difference is significant.
I didn’t pull the centre down, but did pull all the bolts and retorqued them with Loctite to be sure. It looks identical and appears well made.

[vlad01]

Interesting, last time I saw them on Mace's site, I am sure they were only like in the 300-400 price range. Over 600 now. Thats why I thought maybe they were the same unit give the original price that I recall was closer to yours, maybe I saw them somewhere else for that lower price, I could be way off from what I recall.

[brindo]

Stinking hot day but we entered into the first drag meeting for the year yesterday, which also had an Australia Day theme with a grudge match with a neighbouring town a couple of hours away, and a postie bike challenge.
Allegedly only 35 deg but a small sharp scud hit the track and they were racing again in 20 minutes.

Anyway I can confirm that the Nankang AR1 are completely useless. Clearly better than street tyres, but overall disappointed – granted we are using them for a purpose they were not intended but wheel spin off the line was bad. Only got one decent timed run in and only managed a 9.43 @ 77 mph and 2.36 secs for the 60 foot. All the other runs were much slower. Knocked out in the first round of eliminations with a red light - she had a over 1 second handicap and the car rolled forward in the stage - thats manuals for you. We ran 20 psi tyre pressure and while we can go a lot lower there’s no point as heaps of wheel spin off the line and she's only trying to launch at 1500 rpm. But she did win her grudge match against one of her mates dads in an XR6 ute.

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On the upside, despite the heat we had another good day, and the new diff and centre seem to be holding up very well. I am thinking our 60 ft times need to be 2 seconds neat to run a sub 9 second 1/8 mile and that’s not going to happen without a better tyre and diff gears. A shift light would also be handy as currently she is changing gears based on the speedo. Changing at 60kph, then 90kph.

So I have been on the look-out for 2nd hand M75 gear sets in 3.23 or 3.45 ratios but they appear to be unobtainium. I was also under the impression there was a 3.32 ratio available, possibly from the Sigmas??? which I think would be better than the 3.45.

Anyway some pretty solid cars entered. Some photos below of some cars from the day

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[v6bucket]

Well done. 2sec 60' should have you in the low to mid 8 sec pass, 3.45 would work well.

[Gareth]

So cool!!

[vlad01]

Would 3.73 be too high? I have a NOS set to suit M75. Also, I think they make the 3.45 gears as aftermarket now, but I don't know of their quality.

I have the 3.23 in my VP, and I didn't notice the difference. Maybe slightly easier in reverse since reverse is super tall in the T5, forward gears I noticed nothing. I also run 50 profile 15" wheels, so very small diameter and that effectively bumps the equiv diff to 3.45 and I don't feel a difference from 3.08 if I am honest, If timed side by side there might be something in it. 3.45 is 10% over 3.08 and 3.23 is only 5%.