Rear end ticking

[phil_bennett]

Any suggestions welcome. Just driven from Yorkshire to Spa for WEC. Left car park and got an intermittent ticking from rear end. Had diff lube changed, before i left, plug looks dry. Both wheels look OK, both dry. Checked for stones. Trying not to worry, anything I can check, got jack with me so cam get wheel off if needed.

 

[phil_bennett]

Just to add it's a 1978 C3

 

[teamzr1]

You need to expand on the problem
Does the sound happen even when parked at idle ?
When changing the diff fluid, does GM require an anti-slip fluid also added ?

After changing the fluid, did you then do several tight figure 8 turns to work the new fluid in ?

 

[phil_bennett]

Sorry, for delay in replying. And I'm saying this quietly, but the noise stopped on way out of Spa this afternoon.
No sound at idle, only while moving. checked tyres for stones.
Had the anti slip, ordered stuff from Scott, 2 bottles of lube and one additive. Got it booked back in at Nicks for a check in a week or so. Had 2 u joints go in 2008 at Le Mans Classic which Scott sorted, the diff has been fine. Didn't know about the figure of 8 stuff, but plenty of hairpins to and from circuit.
Fingers crossed.

 

[teamzr1]

From GM as of 2007 : (IF the diff has limited slip/ posi-traction)

Date: 4-16-2007
TSB: #07-04-20-002
Document ID# 1961528
Subject: Rear Axle Clunk and/or Chatter Type Noise on Turns
(Drain/Refill Rear Differential Fluid and Add Specified Limited-Slip Axle Additive)

Models:
2004-2007 Cadillac XLR (Including V-Series and Export)
1997-2007 Chevrolet Corvette (Including Z06 and Export)

Condition:
Some customers may comment on a clunk and/or chatter type noise from the rear of the vehicle while making turns.
Cause:
This condition may be caused by slip/stick of the posi-traction clutch plates due to insufficient limited-slip axle additive. As plates slip and stick, a jumping or jerking feel occurs, accompanied by a clunk noise.
Correction:
Important: DO NOT remove the differential cover from the rear or the two sides. It is not necessary to flush the old fluid from the differential.
Drain and refill the rear differential fluid using the procedure listed below. Add the increased amount of limited-slip axle additive specified below.
Raise and suitably support the vehicle.
Clean any dirt from around the differential drain plug.
Remove the drain plug and washer from the differential.
Drain the fluid.
Install the drain plug and washer to the differential.
Tighten the differential drain plug to 35 N·m (26 lb ft).
Clean any dirt from around the differential fill plug.
Remove the fill plug and washer from the differential.
Important: Prior to adding the limited-slip axle additive, the bottle MUST be shaken vigorously for at least 1 minute to mix the additive thoroughly, then immediately poured into the differential.
Add 237 ml (8.0 oz) limited-slip axle additive, P/N 1052358
(Canadian P/N 992694).
Fill the differential with synthetic axle lubricant, P/N 89021677
(Canadian P/N 89021678).
Check the fluid level to ensure it is even with the bottom of the fill plug hole to no lower than 6 mm (0.25 in) below the opening.
Install the fill plug and washer to the differential.
Tighten the differential fill plug to 35 N·m (26 lb ft).
Lower the vehicle.

Once the differential fluid has been changed,
the vehicle must be driven in 8-10 tight figure eight maneuvers to heat the fluid and allow the additive to be worked into the clutch plates.

 

[Chuffer]

Sorry, for delay in replying. And I'm saying this quietly, but the noise stopped on way out of Spa this afternoon.
No sound at idle, only while moving. checked tyres for stones.
Had the anti slip, ordered stuff from Scott, 2 bottles of lube and one additive. Got it booked back in at Nicks for a check in a week or so. Had 2 u joints go in 2008 at Le Mans Classic which Scott sorted, the diff has been fine. Didn't know about the figure of 8 stuff, but plenty of hairpins to and from circuit.
Fingers crossed.

10 or 12 figure of 8`s is a must to bed the additive in and should be done asap after a fluid change . That means within the same day if possible .

 

[teamzr1]

Best doing first short drive to heat the diff fluid up to thin out a bit so flow is quicker