Back Diff, How Much Will It Take?

[TheYorkshireMan]

How much stress do you think the back diff can take?. Thanks in advance

[charlie_morris_minor]

some people run 1300 A serise engines into a standard axle and diff but i would not want to be putting even that into it.

what are you thinking of doing / fitting

[TheYorkshireMan]

Okay thanks, didnt have anything in mind still deciding on a few things for my project.

[PSL184]

It is the half shafts that are the weakest link but uprated ones can be bought. I'm running about 75bhp through mine (standard) at the moment and it's doing OK but I would not be doing any rapid 1st gear accelerations with it. Once the supercharger goes on I'll be fitting an Escort back end and feeding it through a Ford box also.

[Mogwai]

I've been running a 1275 through a std axle for years without issue (which means it will break tomorrow )
I think the diff itself is supposed to be good for about 80-90 bhp
although its torque that kills

[d_harris]

When run ning a 1300 into the standard back axle its the half shafts that break, not the diff. The standard diff is capable of handing more than anything that can be put through even hardened halfshafts

[rayofleamington]

I think the diff itself is supposed to be good for about 80-90 bhp
although its torque that kills

absolutely right! The BHP doesn't make a difference - it's the peak torque * drive train ratios. In a heavy start situation peak torque will be the clutch capacity rather than the engine for a short period.

The diff ratio has an effect therefore there will be less torque on the halfshafts with a 3.9:1 than with a standard 4.2:1 diff.
The earlier diff (4.55:1) will give more torque again.

[plastic_orange]

Diffs are pretty weak too, my wife destroyed a 3.7 diff with her 1098 - I had to replace the axle as the teeth pierced it.

Pete

[rayofleamington]

Diffs are pretty weak too, my wife destroyed a 3.7 diff with her 1098

When I was a teenager (and for a while afterwards too..) I drove rather heavily but have so far never managed to damage a diff. I've yet to hear of one being broken due to a higher performance engine either - they did use the same style diff on the 1.5 engine for Rileys.

[TheYorkshireMan]

Thanks for all the input, extremly helpfull .

[plastic_orange]

I didn't mention the half dozen 3.7 diffs I broke when running an MGB engine in the Minor until I went to Ford.

Pete

[philsheredan]

Hi I'm running a 1275 turbo thru standard midget box and clutch with 4.2 standard rear end AND adjustable boost so I can go silly with it occasionally and I find that theres so much lag pulling away it almost feels as gutless as the 1098. By the time the turbo is spinning enough to notice, the clutch is up we're out of the junction and the fags lit !! Only then does the panic set in with images of rods n cogs parting company. There is a super strong en24 shaft available at 350 quid a pair and you could use a limited slip diff in the back instead and that should up the power it can take.

Phil<br><br>

[Parker]

Yes my dad always tell me that he used to snap HALF SHAFTS like no tomorrow in his moggie