Hilux diff drum to disc conversion

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Mat42
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Hilux diff drum to disc conversion

Post by Mat42 »

Hi guys looking for a drum to disc conversion for hilux diff engineer has suggested running fg rotors
Harv
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Re: Hilux diff drum to disc conversion

Post by Harv »

The dragster that I'm building runs a Hilux/Hiace diff. It's been shortened... a lot :). The axles are Williams, Chev pattern. Runs mid-model Conformadore (VN, VP, VR, VS) rear disks and calipers.

Cheers,
Harv
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FRANK BASILE
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Re: Hilux diff drum to disc conversion

Post by FRANK BASILE »

Might be a bit dicey with the Commodore rotors on the Chev/HQ axles. They are not metric equivalents. Plenty of past discussion regarding stud stress when using the wrong wheels.
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zuffen
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Re: Hilux diff drum to disc conversion

Post by zuffen »

Frank, I thought the same but then I re-read the Post and he's using Commodore Callipers, not discs.
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Harv
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Re: Hilux diff drum to disc conversion

Post by Harv »

Commie rotors, and calipers. Chev axles, Chev wheels.

Yep, there is a difference in pattern - Chev is 4.75" (120.65mm), Commodore is 120mm. That makes a big difference when bolting mismatched wheels up, as the wheel nut tries to bear a poofteenth sideways on the wheel face. That puts a bending stress on the stud, and according to legend can snap studs. I know no-one who has actually snapped one that way, but the theory is directionally correct.

A rotor though does not get a chance to bear on the stud (assuming it has enough clearance to actually fit over the studs in the first place). It is smooshed flat between the diff flange and wheel. I reckon it cannot impart a bending force on the stud, but welcome your views.

Cheers,
Harv
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zuffen
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Re: Hilux diff drum to disc conversion

Post by zuffen »

As long as the rotor is hub-centric and not stud-centric there shouldn't be a problem.

However I would think the odds of the centre bore being identical would be slim.
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Sudsy
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Re: Hilux diff drum to disc conversion

Post by Sudsy »

Harv wrote: Tue Feb 07, 2023 7:35 am Commie rotors, and calipers. Chev axles, Chev wheels.

Yep, there is a difference in pattern - Chev is 4.75" (120.65mm), Commodore is 120mm. That makes a big difference when bolting mismatched wheels up, as the wheel nut tries to bear a poofteenth sideways on the wheel face. That puts a bending stress on the stud, and according to legend can snap studs. I know no-one who has actually snapped one that way, but the theory is directionally correct.

A rotor though does not get a chance to bear on the stud (assuming it has enough clearance to actually fit over the studs in the first place). It is smooshed flat between the diff flange and wheel. I reckon it cannot impart a bending force on the stud, but welcome your views.

Cheers,
Harv
That is true as long as the centre bore is matched to the axle spigot as Zuffen has already mentioned. Easily fixed if you have access to a lathe by either machining the centre out if it is too small or making a sleeve if too big. Then just have clearance on the studs
Regards Bob
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Sudsy
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Re: Hilux diff drum to disc conversion

Post by Sudsy »

Forgot to mention, if you run the ford discs you won't have to worry about the studs as hi lux is ford pattern.
Regards Bob
Mat42
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Re: Hilux diff drum to disc conversion

Post by Mat42 »

Sudsy wrote: Wed Feb 08, 2023 9:11 am Forgot to mention, if you run the ford discs you won't have to worry about the studs as hi lux is ford pattern.
Is there any plates available to be able to fit the ford brakes to the hilux diff and front spindle
Harv
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Re: Hilux diff drum to disc conversion

Post by Harv »

One thing I like about the forum is that it makes me think. Checked with the diff shop about how the rotors are located. The Williams axles are ordered with the centre boss (spigot) to match the Commodore rotor centre bore. The only thing that will need doing is that the wheel stud holes in the rotors will need to be enlarged (offset drilled) to suit the 1/2"UNF Ford studs.

Hilux diff, Commodore rotors, Chev pattern, Ford studs. League of nations :mrgreen:

Cheers,
Harv
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zuffen
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Re: Hilux diff drum to disc conversion

Post by zuffen »

I made dogbones out of 1/2" plate to mount Nissan Patrol callipers to my Mitsubishi L300 front hubs.

It isn't hard to do and it may need a little welding for spacers but the welding is only to hold them whilst the bolts go in.

My Engineer and the RMS Inspectors were happy with what I did.
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Sudsy
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Re: Hilux diff drum to disc conversion

Post by Sudsy »

[/quote]

Is there any plates available to be able to fit the ford brakes to the hilux diff and front spindle
[/quote]

The ford calipers are a pain to fit to the Hilux diff. The Nissan skyline or pintara are the same calipers with just the 2 ears on them for mounting so much easier to adapt
Regards Bob
Harv
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Re: Hilux diff drum to disc conversion

Post by Harv »

Skylines and Pintaras use the BW78 diff, the same as many Commodores. Wonder if the caliper mounting is similar?

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Harv
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Sudsy
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Re: Hilux diff drum to disc conversion

Post by Sudsy »

Harv wrote: Wed Feb 22, 2023 3:04 pm Skylines and Pintaras use the BW78 diff, the same as many Commodores. Wonder if the caliper mounting is similar?

Cheers,
Harv
Haven't looked at the commodore calipers as i wanted the integrated handbrake mechanism. Not sure offhand of the boltsapcing on the skyline calipers
Regards Bob
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FRANK BASILE
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Re: Hilux diff drum to disc conversion

Post by FRANK BASILE »

Unless there was a change along the way. Commodores used hat type disc rotors with a drum brake style handbrake set up
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