Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 BB Backlash

Does anyone know what the back lash should be on the on the prop flange. I have .011".

When I rock the prop shaft back and forwards there is quite a clonk just like a nackerd diff.

From my old MK2 Cortina days I'm sure pinion to crown wheel used to be .003-.004", which translates to an awful lot less than .011" at the input flange.

I have also just about managed to flush all the black goo out with lots of diesel and patience, not a quick job to say the least especially when I took the drain plug out and got most of it up my sleeve.

Now I plan to replace the egg cup full of tar with 450ml of Millers EP140 and hope it will run a little quieter.

Was startled that any TM guy would be watching Big Brother to even worry about a backlash

Regret I cant help with your actual query Dab.

Cheers

I think the Clonk might well be a knackered BB??

I hope not ...for you!

Dab, when I read your .011" backlash I thought that sounded about right. I did some checking on the rear ends I used to setup, Ford 9" and GM 10 and 12 bolts. They all seem to be in the .008"-.014" range and when reviewing the smaller diameter ring gears, they did not drop in backlash specs. Racing gear sets tend to be set up a bit looser.

Now some others did have .006" to .010", but most were all in the low to mid teens.

I'm curious though how you measured your backlash. When I setup a 3rd member like a 9" Ford, I have my dial indicator mounted on the case and I physically have the tip on the ring gear tooth 90 degrees to the rotation so I have a good feel for the direct motion. If you're measuring the amount of rotation a driveshaft has before the sprocket moves, it not going to be a true backlash reading of the ring and pinion gears.

I'm not certain, but is the output shaft of the BB pressed into the ring gear or is it splined to the shaft? If it's splined you can also be picking up some "slop" in the spline. But it's not uncommon to get some twisting of the driveshaft before anything happens to the output sprocket.

I certainly hope that the clonk is not indicative of an expiring BB. When I rock my car back and forth out of gear I also get a clonk. And it's only done 500 miles!

Hi Dan

I know my measurement is not a true backlash measurement as to do that would require stripping the BB to get at the gear teeth.

I measured mine by applying the hand brake to lock the rear wheel then used a DTI against the prop spider, then by gripping the prop shaft by hand just rocked it back and forth. Thats where the .011" came from.

This measurement was just to try and asertain what is within acceptable limits.

For all I know it could be middle limit, or miles out. Who knows?

I'll ring my dealer tomorrow.

You mean your dealer will know??!!! :santa2:

Well, I asked Quaif who referred me to MMC who referred me to my dealer.......

The blind leading the deaf...