Occasionally (can be warm or cold), pulling away in 1st or reverse can give a bad chatter and all over car shake. The shaking symptom is much worse in 1st, but the chattering is worse in reverse if I’m quickly backing onto my drive or some of the parking at work. This can make it a little annoying or even embarrassing to drive the car in traffic as it can do it a lot then.
At first, it felt like clutch slip, but I’m about 90% sure it’s not this as every other gear will; take up drive really solidly and well, without these symptoms. Even if you’re cruising in 4th or 5th and then give her say, 2nd or 3rd, she’ll take it up with no slip and push hard. I did get a bit excited the other day when using my Google-fu, to find that the U-Joints on the propshafts can go bad and develop play - checked mine this morning and it’s solid! Only thing I can find around the diff is a slight clunk as the drive changes direction, but my feeling is that this is relatively normal behaviour.
Now, I say this doesn’t happen in any other gear, but when I had the car in the air, looking for this, I had it in any of the five gears at idle speed and it would occasionally sound like it was doing this weird chattering/slipping. I just don’t seem to be able to lock it down to anything in particular, so any advice would be much appreciated!
Just to add as well, that as soon as the drivetrain is unloaded with the clutch disengaged, this disappears entirely and the car settles again. I don’t ever notice that the motor struggles and revs drop, which leads me to believe it’s not clutch slip nor control. Not ruling that out, though!
I had the opportunity to get the back end lifted today, so had both wheels off and gave everything a good tug, shake etc. All of the suspension components, including bushes all feel solid.
Now, there seems to be play in the driveshafts - I say plural because I can’t track down which side it is.
With both sides off the ground, wheels off and the car running in gear, there is a pronounced rattle (don’t worry, I had the calipers and discs off, so it wasn’t them). This rattle seems to be coming from both sides, and can be felt through the driveshaft and the diff. This is the same feeling of play that I mentioned before in the diff. Is there a part in here that is known to fail? Unfortunately, I wasn’t able to proceed further in investigating as I don’t have a socket large enough to remove the driveshaft nut!
Refit the discs and calipers and then put your handbrake on (engine turned off) then turn/twist the propshaft by hand, i would be happy with 1/8-1/4 turn of back lash any more i would be getting concerned.
Back lash between the crown wheel and pinion would vary between manufacturers anywhere from 8-16thou, i don’t know if the mx5 diff can be adjusted but most diffs can.
You can’t really check the drive shafts in situ as wear in the planet gears and shims would show the same both sides.
New heavy diff oil can help hide a worn diff.
I would still suspect a warped clutch friction plate or blued pressure plate, even a heat warped ring gear plate.
I have tried this movement beforehand and it matches the tolerances you’ve suggested.
I’m waiting for parts actually to change the clutch and perform a service on the car as we speak - I’m planning to do this on Tuesday and will update the thread afterward to see if this has helped at all.
Sorry for the late reply, I’ve been unable to get back in the car since doing the work! I was only able to get back in it about an hour ago, actually.
The new clutch kit appears to have solved the problem! Also, having had the box off the car and refitted seems to have solved the 3500 RPM grinding/rattle noise that I had before.
I’m confident that this has solved the issues that I described at the start of the thread, but time will tell once I get some more miles on her. For now, though, she’s back on the drive after misfiring on the initial drive. Believe that I’ve just not fixed the new HT Leads down correctly when I replaced the spark plugs! She had no indication of a miss before, so I’m confident in what it is. Just waiting until tomorrow morning so it’s light when I take a look!#