Jerking on deceleration

[Austin09]

944 turbo jerking at slow speeds on deceleration. Worst in 1st gear but also in 2nd.
Is this normal or is there things I should check for wear?

It happens when driving at slow speeds e.g. if I let off the accelerator to slow for a speed bump it jerks.

I’m looking to get a checklist I can go through and narrow down the problem. I’m thinking perhaps:

- throttle side. It’s got a new TPS.
- I’m ruling out air flow or fuel mix because it’s not at revs where it would stall
- could it be CV joints
- clutch is strong it’s not got a high bite point but at least 25k miles and 15 years old maybe more

Advice on what I can check myself please before going to a specialist

[scam75]

Hi Austin

My money would be on CV joints, mine was doing this until I replaced all 4 CV's and the issue went away completely.

If you dip the clutch when approaching speed bumps, and it doesn't jerk, bad CV's will be confirmed.

Stuart

[Austin09]

Thanks,

I’ll start my inspection there then and look for a split boots and feel for play on the rear wheels.

The CVs were new 10 years ago c. 10k miles ago

No jerk when I dip the clutch it’s decelerating in gear 1st or 2nd coming up to speed bumps and the like it’s most noticeable

[scam75]

No worries. I suppose miles is a big factor but I've found new CV's last about 10 years with me, about 60k miles. Had one knocking a couple of years back but upon inspection all 4 had seen better days, the one nearest the exhaust tends to go first.

4 CV's (GKN OEM) were about £160 from ECP and solved my issue. Only ever replaced them singly before but doing all 4 made things so much better and IMO worth doing.

Stuart

[Austin09]

Thanks
I’ll let you know how I get on. If the grease escaped then perhaps they have worn prematurely but barely done any miles.
I’ll also test my TPS with my multimeter cos that’s newish but I don’t recall this issue after fitting it only the other day for my first drive of the year

[Austin09]

I jacked up the car and inspected the boots and checked for noises and play on the wheels and no indications there are issues with either driveshafts.

TPS is making an audible click when off the throttle and the resistance readings is as you'd expect in line with clarks garage. Its new so can rule that out.

I need to do drive shaft seals so I will probably pull the CVs off and inspect and regrease but think I need to look elsewhere.

Any other suggestions?

[briggy]

Does it also jerk when accelerating as well as decelarating? If so, it could be the clutch. The rubber centre disintegrates over time. This is exactly what happened with my old S2, years ago.

[tr7v8]

The drive shaft that dies soonest is the one above the exhaust as the grease gets cooked out. I've done a few and on one the grease was like cement!

[Austin09]

Interesting. I’ll take it off and do the drive shaft seal in the next couple of days and see if it needs regreasing.
It’s not too expensive for a new drive shaft but I don’t want to replace if I don’t need to if the problem lies elsewhere.

[Austin09]

I lifted the back of the car and checked the drive shafts today.

I am not hearing a clicking and there’s no splits in the boots.
I don’t know how much play is normal on these cars..I tried to video the amount of play - anyone able to confirm is this is normal or indicates wear?

I need to take off the transmission side tomorrow and do the oil seal when it arrives so I can inspect inside then.

https://youtube.com/shorts/z5fe81fwjjo? ... JKgQC5VdGk

[tr7v8]

Does it also jerk when accelerating as well as decelarating? If so, it could be the clutch. The rubber centre disintegrates over time. This is exactly what happened with my old S2, years ago.

I thought the Turbo clutch had no rubber cush? I thought it was springs only. The current replacement clutch is the Turbo style clutch anyway.

[scam75]

Does it also jerk when accelerating as well as decelarating? If so, it could be the clutch. The rubber centre disintegrates over time. This is exactly what happened with my old S2, years ago.

I thought the Turbo clutch had no rubber cush? I thought it was springs only. The current replacement clutch is the Turbo style clutch anyway.

Correct Jim.

[Austin09]

I’m changing my drive shaft seals and before loosening the bolts I wanted to check the right side again for play
I didn’t notice this noise on the left side which I’ve now done.

Does this seem normal or indicate I need to replace drive shaft?
I’ll upload the status of the CV grease when it’s off.

https://youtube.com/shorts/HPHNPCwF8r0? ... 5N-uaxdac_

[tr7v8]

End to end isn't normally the issue. You need to hold the centre shaft & move the wheel (handbrake OFF.) & feel the play.
Knackered CVs normally sound like a running horse, with distinctive clip-clop noise. Although the two cars I got heavily involved with (Mine and another) seemed OK. It was only on removal & stripping & cleaning, I discovered one of mine was well through the case hardening. On the other car, we caught it in time. The grease was like sawdust on the one above the exhaust but the joint it self was OK.
Rebuilding them is a disgusting 'orrible job. I think a 500g pot of grease did a pair of driveshafts. I bought new CV boots as well. They weren't expensive. The joint (I only replaced one) I think came from an OPC.
Be warned the bolts are technically stretch bolts, whether you replace them is up to you, BUT on the other car the owner replaced them & even then, on torquing it up one broke! It meant another strip & clean, re-grease of that end which was a PITA!

[Austin09]

Thanks a lot

I wasn’t sure if the bolts were stretch as I can’t load my workshop manual anymore as I don’t have a cd drive.

In that case I should buy some it’s not the sort of thing to save money on. They haven’t done much mileage and the CV grease is still thick and black so I’ll do the seals and replace the driveshafts with new bolts.

There is no rotational play whatsoever.
I’ll have to investigate the knocking noise and jerking when I’ve got the car driving again.