Power limit of M78 diff

[SHMIKO_S14A]

Hey guys, I’ve got a BA XT with a Barra 240T in it and I’m looking at putting some more power through it soon, wanting to know what sort of power the XT M78 diff/cradle/shafts can handle with out smashing it to pieces.

 

I’m also planning to put a TrueTrac in it because obviously it’s currently an open wheeler (gayyy).

 

I don’t really wanna go down the road of doing an M86 cradle swap unless I absolutely have to but I’m aware they are much stronger than the 78 series.

Edited 01/02/18 06:03 AM by SHMIKO_S14A

[k31th]

not many people test the limits of these diffs, in terms of power, because you're essentially limited by the N/A engine in the first place, not the diff.

 

But from what I've heard, they don't last long with reasonable power, if you have reasonably sticky tyres. If you're going to run tyres that don't grip very well, then it'll probably be fine.

[Puffwagon]

Here is a quote from the internet therefore it must be true, "The rear is officially rated @ 220 kW = 295 HP @ 435 Nm = 320 lb/ft".

 

The same person reckoned that they had seen one take 500+hp for several years but that wouldn't account for the ford specific bits.

 

As hamster nuts said, it comes down to tyre choice, along with road surface and how you drive it.

 

Also there's nothing wrong with doing a big, phat, long, thicc, fully sick, hectic, juicy, gayyy arsed single wheel skid for 500 metres down the road.

[NA_TURBO]

I just swapped out my M78 diff that had survived 3 1/2 years of drag strip use, spirited driving with 242rwkw and was fine. Upped power to 330rwkw and it started showing signs of wear.

Clunking, a slight whirring noise and the seals started leaking was a sign it wasn't happy.

M86 swap isn't so bad. Basically bolts right up doing a cradle swap. Need to check tailshaft lengths and pinion flange sizes to make sure it will all go together. But definitely worth swapping to an LSD in a turbo car.

[NA_TURBO]

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