Offroad-Express

I seem to be missing something.

I'm forever reading about some-one wanting a diff head for their toy, then some-one else will ask if they want the front or rear.

I have never pulled a diff head out of a 4x4, but I would have thought that they would be exactly the same and only the axles, housing etc would be different.

Will some-one clarify.

In a solid axle truck (pre-86) they are the same front and rear... interchangeable...

In the IFS trucks the front diff was smaller... 7.5" ring gear as opposed to the 8" ring gear in the rear diff (the rear diffs are the same regardless of IFS or solid axle).

There were also some housing changes - ie the V6 normally had a beefier housing for the rear diff, although the same 8" ring gear...

The prado front diff (solid axle models) was a high-pinion, but once again it was 8" so could be used in a Hilux (or possibly as a rear diff, not sure how strong they would be in that app... the housing doesn't look that beefy compared with a normal low-pinion diff).

Clear as mud?

Steve

I'm confused as to why they wouldnt be the same. I'm sure there must be a good reason, but what it would be confuses me. If one is stronger than the other, then why not just use the stronger option, they are still the same ratio ?

BTW, thanks for your reply

Size I would think... smaller diff gives better clearance and is plenty strong enough for the purpose it was intended for...

Besides they had the 7.5" diff setups from many rear-wheel drive cars of the age like Supras etc... so it wasn't a new design just for the Surf... I believe you can even bastardise a 7.5" LSD from a supra into the front of an IFS surf... never seen it done tho... one of those urban legend things

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Oh, and they have to be the same ratio... otherwise you get driveline locking... the size of the diff does not affect the drive speeds, its just a more compact version...
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Steve

SupraLux wrote:... I believe you can even bastardise a 7.5" LSD from a supra into the front of an IFS surf... never seen it done tho... one of those urban legend things...

Not an urban legend, Have fitted one to a mates IFS front, makes a difference, its still IFS tho...

how hard wsa it smurf. what ratios do they come in? so i take it they are stronger??

Cheers Pete

pete, we bought it already done, but there is info on some US sites about doing it. It looks reasonably simple to do looking at the housing.
It looked as if the ring gear from the surf was used, must have been really as I doubt a RWD supra would have a ratio of 4.5:1

I couldnt see that the ratio would be different, you would end up with the front dragging the rear, or the rear pushing the front. But, I also took it for granted that both front and rear diffs would be the same.

Might need to look into the supra idea, might be just what a little zook needs, or should that be a well hidden toyota.

I no this is a old thread bla bla bla but is there a paticular year supra that the diff came out of??, been thinking about this for a while now, Like the rest of my plans