Pinion angle on ‘new’ Torana diff

[Vanman]

Gday brains trust, I’m going to swap out the HR diff in my van for a recently acquired LJ diff to give me better rear wheel/tyre clearance. Just checking if I should do the mounts in a jig, or if that’s overkill? Also, any advice on pinion angle? I’m assuming 2-5 degrees? My rear springs have been reset and reverse eyed to be 3.5” lower than standard.
Cheers, Matt


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[Blacky]

I made a simple jig to mod Torana diffs, just used a stock diff as a template to pick up spring mount points, and a support to hold the pinion end of the diff.
Mounted new spring pads in jig, drop diff in , centre it - or give it an extra couple of mm towards the drivers side seeing as the left one always seems to rub worse then the right , and weld away. Same pinion angle as stock .

[Errol62]

I would be mocking up with the car on the ground and engine in position if it were me, just to get the correct angle for your set up Matt. I measured the angle on a stock EK diff recently and I found the centre flange to be tilted up about 6 degrees relative to spring pads. But lowering by flattening the leaf springs would appear to result in the pinion axis rotating down forward, towards horizontal.

Non standard motor is another factor to consider of course, depending on how front and rear mounts are set up.

People (drag racers mainly) say to allow for the pinion riding up under load, but I wouldn’t give it more than one degree myself.

Once the angle is known, a variable jig would be handy. Not sure if Glen’s is variable, or will cater to different axles. I do know it was set up to use the Rodtech HT saddles.


FB ute fixer upper, EK van on rotisserie

[Errol62]

I agree about the rubbing on passenger outer like blacky says. My ute is the same.


FB ute fixer upper, EK van on rotisserie

[Vanman]

I made a simple jig to mod Torana diffs, just used a stock diff as a template to pick up spring mount points, and a support to hold the pinion end of the diff.
Mounted new spring pads in jig, drop diff in , centre it - or give it an extra couple of mm towards the drivers side seeing as the left one always seems to rub worse then the right , and weld away. Same pinion angle as stock .

Thanks Blacky, have you got any pics of how you did the spring pad brackets on your jig? I was going to just set one up using old diff that had pinion angle bracket with spring pads at 0 degrees, then just drop the torana diff in and then locate the new pads brackets at 0 degrees at the appropriate spacing. Your method sounds a little more bomb proof though! Best cut and weld once!
Cheers, Matt


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[Vanman]

I would be mocking up with the car on the ground and engine in position if it were me, just to get the correct angle for your set up Matt. I measured the angle on a stock EK diff recently and I found the centre flange to be tilted up about 6 degrees relative to spring pads. But lowering by flattening the leaf springs would appear to result in the pinion axis rotating down forward, towards horizontal.

Non standard motor is another factor to consider of course, depending on how front and rear mounts are set up.

People (drag racers mainly) say to allow for the pinion riding up under load, but I wouldn’t give it more than one degree myself.

Once the angle is known, a variable jig would be handy. Not sure if Glen’s is variable, or will cater to different axles. I do know it was set up to use the Rodtech HT saddles.


FB ute fixer upper, EK van on rotisserie

I tend to agree Clay, but there ain’t much room under there for my big boofhead, once she’s on the ground!!


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[EK283]

Really the only way to do it right is to find what your gearbox output shaft is at, then subtract 1 to 2 degrees from the final diff location.

That means with the springs compressed and in their final load bearing position.

This allows for drivetrain torque and you would be suprised how much the diff winds up even at cruising speed.

Optimum is for equal angle at the gearbox and diff under normal load.

PS remember also that the diff yolk is not in the center off the diff in an EK.

Regards Greg