Drive train shunt

[Let off some steam Bennett]

I have recently had a body off chassis restoration including a rebuilt diff and gearbox. I still find the drive train a bit shunty including what i think is a very slight nock from the diff when i change gear, this depends on how smooth i am with the clutch though. Is this normal, its been that long since i drove the car at any length as the chassis resto took 18 months to complete

[Snaaakeey]

Hmm.

I would think one of these.

Prop shaft UJs
Diff ( crown/spider)
Diff bushes
drive shafts

You have done the bushes and diff soooo.

I think there is some play built into the diff but how much is too much? my diff needs doing next year as i can rotate the prop shaft 8-10mm before it takes up the slack but i cant really notice the back lash. it more a feeling/ a slight knocking through the body sometimes when cursing.

Anyone out there with zero back lash in the drive train?

[Let off some steam Bennett]

Snaaakeey said:

Hmm.

I would think one of these.

Prop shaft UJs
Diff ( crown/spider)
Diff bushes
drive shafts

You have done the bushes and diff soooo.

I think there is some play built into the diff but how much is too much? my diff needs doing next year as i can rotate the prop shaft 8-10mm before it takes up the slack but i cant really notice the back lash. it more a feeling/ a slight knocking through the body sometimes when cursing.

Anyone out there with zero back lash in the drive train?

Im thinking its some play built in to the diff, its nothin major but i just hoped once i had had the chassis and diff rebuilt it would go away

[Let off some steam Bennett]

Snaaakeey said:

Hmm.

I would think one of these.

Prop shaft UJs
Diff ( crown/spider)
Diff bushes
drive shafts

You have done the bushes and diff soooo.

I think there is some play built into the diff but how much is too much? my diff needs doing next year as i can rotate the prop shaft 8-10mm before it takes up the slack but i cant really notice the back lash. it more a feeling/ a slight knocking through the body sometimes when cursing.

Anyone out there with zero back lash in the drive train?

Diff bushes done and i have just changed CV joints as the new ones i supplied when they rebuilt the chassis were not packed with enough grease and they lasted 200 miles

[Snaaakeey]

I was talking to the owner of www.gearboxman.co.uk whom is apparently the bees knees on these diffs. He did say they are inherently like it to some degree.

Its bloody annoying when you have something like this that you assume is an issue so you throw a couple of grand at it and it makes no difference at all.

We need a wiki of "they all do that"

[Let off some steam Bennett]

Snaaakeey said:

I was talking to the owner of www.gearboxman.co.uk whom is apparently the bees knees on these diffs. He did say they are inherently like it to some degree.

Its bloody annoying when you have something like this that you assume is an issue so you throw a couple of grand at it and it makes no difference at all.

We need a wiki of "they all do that"

I'm kind of coming to that conclusion, its very annoying though

[Dudley99]

They were a bit agricultural when the car was new, 25 years ago. They were never in the Porsche league for refinement, because there was never the development budget or testing and development. How many prototypes did they ever build? How many development and test engineers did they have?

They didn't even get the engine right, which is why so many blew up so quickly, which basically brought the Wheeler era to a close, so a bit of driveline shunt, they were never going to resolve.

The original owners liked them to be raw and a bit agricultural, otherwise they would have bought a Porsche.

[Let off some steam Bennett]

Dudley99 said:

They were a bit agricultural when the car was new, 25 years ago. They were never in the Porsche league for refinement, because there was never the development budget or testing and development. How many prototypes did they ever build? How many development and test engineers did they have?

They didn't even get the engine right, which is why so many blew up so quickly, which basically brought the Wheeler era to a close, so a bit of driveline shunt, they were never going to resolve.

The original owners liked them to be raw and a bit agricultural, otherwise they would have bought a Porsche.

👍

[sixor8]

Give it a rest, Dudley99, it's boring. The OP asked for ideas about a solution, not your constant barbs... Lucy.

[Let off some steam Bennett]

sixor8 said:

Give it a rest, Dudley99, it's boring. The OP asked for ideas about a solution, not your constant barbs... Lucy.

There must be a solution to these problems

[s6boy]

It would be interesting to hear from S6 owners who have changed ECU and/or had throttle body work whether any apparent drive line shunt was improved.
I sometimes get what I perceive as minor shunt but have put that down to careless throttle use but wonder if it could be mapping at small throttle openings.

[Let off some steam Bennett]

s6boy said:

It would be interesting to hear from S6 owners who have changed ECU and/or had throttle body work whether any apparent drive line shunt was improved.
I sometimes get what I perceive as minor shunt but have put that down to careless throttle use but wonder if it could be mapping at small throttle openings.

I have had my throttle bodies done and in all honesty it drives no smoother than it did before, i think its just another way of specialsts removing 1k from your bank. Its no more responsive or smoother, maybe my throttle bodies were in good order.

[mk1fan]

I wonder if the few that have replaced the hydralock with a Quaife mech diff have seen and improvement? Tamy is terrible with a drivetrain knock.

[Snaaakeey]

Dang.

I may well leave my diff alone then. Also have a similar issue with idle rpm and if it needs attention to the the throttle bodies.

[Let off some steam Bennett]

mk1fan said:

I wonder if the few that have replaced the hydralock with a Quaife mech diff have seen and improvement? Tamy is terrible with a drivetrain knock.

Mine is running a factory hydratrack diff, I had it rebuilt as I kind of wanted to keep it to the spec of the factory red rose

[v8sag]

Not bad for a forum read understanding diff backlash on the m78. https://pcmhacking.net/forums/viewtopic.php?t=3876

[The Three D Mucketeer]

On my 2006 Tuscan Convertible got my M80 Diff reverted to the older M76 Diff and changed the prop shaft to match and the shunt was eliminated .
(It's what the factory did , if there were complaints )

Edited by The Three D Mucketeer on Friday 31st October 07:16

[Basil Brush]

Snaaakeey said:

Hmm.

I would think one of these.

Prop shaft UJs
Diff ( crown/spider)
Diff bushes
drive shafts

You have done the bushes and diff soooo.

I think there is some play built into the diff but how much is too much? my diff needs doing next year as i can rotate the prop shaft 8-10mm before it takes up the slack but i cant really notice the back lash. it more a feeling/ a slight knocking through the body sometimes when cursing.

Anyone out there with zero back lash in the drive train?

My '00 std diff with 45k miles on it has about 3 to 4mm movement at the edge of the input flange. That's with new bushes and CV joints just fitted.

[Let off some steam Bennett]

It's a case of they all do it then. I guess I just thought having my chassis done and everything rebuilt it would be better. It's no great trouble just a bit annoying

[v8sag]

A little backlash isn't the end of the world, but it's not a case of" they all do that" as they don't. If you isolate the clunk back to the diff, i would send it back to the diff rebuilder. It would be a shame since you've spent hard earned for component failure a little further down the track.
Any diff lash I've experienced I haven't heard or felt the clunk after selecting direction of travel, either in first or in reverse, certainly not continuing in further up or down shifts.