Late differential issues.

[ClassiChimi]

I've got a sneaky feeling my diffs a bit sloppy, as much as it is to much power going through it i feel the years of slight shunting have taken a tole. I've not really experienced any other Chimaera on local roads etc so it's hard to know if I'm inventing an issue.
Replaced all driveshaft CV joints a few years ago and I've been gentle ever since but still on off throttle there's slack, is it just a trait or is my diff loose,, driving fast it's not an issue but slow stuff I have to be very careful as to not introduce judder,,, engines running bang on, no real shunting anymore since Ecu upgrade but that slop is still there, prop shaft UJ's greased and found to be strong and tight!
Waffle,,, my question
With the later cars if I was to jack one side off the ground and try to rotate a rear wheel ( in nuetral ) what should I expect to find in a good or bad diff.
How much movement of the wheel should I expect before it locks,,

Thanks in advance Alun

[ClassiChimi]

That's a relevant point but not really what I'm talking about, just that slack when reengaging gearbox off the clutch etc, just wondering what else I can play with on the car really,

I'm now able to drive in say 3rd gear from as low as 800 revs and gently accelerate with no shunting at all, slightest hint at 14-1700 revs but it's barely detectable and doesn't cause transmission clunking, it's now more on/ off throttle and gear changes that I find have to be matched perfectly but then that's half the fun I suppose,
It's more a question of if my dif is good rather than thinking it's bad!
The wheel turn test as I'll now call it, hah, so what should I expect, i can turn my wheel fairly freely for about 2/8 th of a turn, no real noise from the dif, could I use a slightly thicker grade oil in there or is that bad practice.
Just trying to perfect the car more

[ClassiChimi]

Brerabit said:

Without doubt fuelling/ignition problems can be responsible for the irregular issue of power i.e. shunting, hunting, surging etc. and these symptoms can exacerbate and even cause wear in the drive train. However, once that slack exists no amount of mapping is going to replace metal that’s been worn from the numerous components between the engine and the wheels. I’m in a similar situation to ClassiChimi; I’ve invested heavily in getting my RV8 to behave in a civilised manner with a Canems EMS, Stage III heads and other induction mods and now it delivers as much wide range, smoothly delivered power as is reasonable to expect from a normally aspirated but significantly modified 4.0L engine and yes, the clanks and clunks I used to experience when trying to crawl along in traffic are considerably lessened - but even the slightest reversal of load immediately remains me that something isn’t as snug back there as it should be. So far I haven’t been able to trace it to the prop or drive shafts which leaves me wondering/worrying that it may be the diff. So I would also appreciate any straightforward check that would indicate whether the problem lies in that big chunk of expensive GKN hardware - or elsewhere.

Well put sir,, it's not just me then,,, Yep it's the last line of interest to me in developing the manners of the car, I suppose you can only really check by opening and looking at the dif gears etc,

[ClassiChimi]

I havnt got a lot of Tvr man funds in the kitty so I'm not really aiming on doing much now but it's something I often think about when driving, my dif is pretty silent so it's not something I'm expecting to go bang anytime soon,, maybe a tweak to the map may help but it's skirting the problem, it's that slack, I'll do the prop test again and update, maybe just change the UJ's at the next service and see what that does. I'm pretty sure my prop UJ's are original, 61,000 miles now so they've had a good innings.

[ClassiChimi]

Oly, I remember seeing that, keep us posted please,,,, I'm glad I raised it now,,
What I will say is I had all four drive shaft CV joints replaced and 3 new dif mountings within days of owning the car,,, drove our the garage and it felt exactly the same, top bush was foooked so I was right to change em but it didn't make any difference at all !
Combination of worn gearbox and dif, from the shunting, my car was owned by one person for most it's life, his money was spent paying it off I think! It's inherently a shunter I reckon, always suffered with it but only now has it been eradicated to a large extent,, it was never very bad but I also think the car spent a lot of its life in and around Edinborough so always stop start, gearbox itself feels tight and rather lovely but somethings not quite perfect.