Menu toggle

RS Drivetrain "Click" LSD or Something else?

K

kasbridge

PCGB Member
Member
All,
As some of you know I am in the process of importing a 964 RS from Germany and one of the things I noticed on the test drive was an audible click from the powertrain when coming on and off the gas when the steeering wheel is not dead straight ahead.

The click is only present when turning in and not when driving straight, it is therefore not (I dont think anyway) a driveshaft problem.

Does it sound like a worn LSD?, Is there a simple test to check the LSD is healthy?

If it needs repair can it be done with the gearbox in situ? Cost?
[FONT=verdana,geneva"]Clutch is new.[FONT=verdana,geneva"]
I am happy with all the usual RS gearbox chatter but this is something different.

Never had a car with LSD before. please help!!!

The car has 50k miles and has hardly been on track.

Thanks,
Kevin.[FONT=verdana,geneva"]
 
My GT3 clicks a lot when coming on/off power and often when moving off. It's especially bad if you've just been round a roundabout, i.e. you're likely to hear the click, or a series of clicks, as you apply power. Interestingly I don't notice it if the windows are shut. I don't think there's an easy test. I've been assured that there's nothing wrong with my diff. I saw another GT3 jacked up recently and as you turned a rear wheel the other wheel didn't move at all. I questioned it and was told that it does not mean that the lsd plates have gone.
 
Kevin

I have now checked my file and you can get the lsd out without removing the gearbox. This is how it was done on my car

1. Remove driveshafts from gearbox flanges
2. Drain gearbox oil
3. Remove flanges
4. Remove diff plate cover studs and cover
5. Remove diff and strip down on bench.

That is directly taken from the worksheet.

Hope that helps. Unfortunately, this work was done with a heap of other things so I cannot give you a price.
 
I have noticed the odd lurka "independent specialist" on the forum. Would be great for them to comment, particularly on how they check the diff in the car and pronounce it worn or not?
 
Laurence,
The technical specs for this are in the porsche 964 workshop manual. To test you need to remove the diff, put it in a vice to fix one output shaft and then put a torque wrench on the other and see how much torque is needed to twist the free output, from memory anything less than 20Nm is a fail for the 20/100 lsd. There is a different figure for the 40/100 slip diff.

This does not stack up with the 911 and PW 964RS article that says if you jack one wheel up and you can turn it then the diff is knackered!

The torque test in the manual could not be reliably applied to the rear wheel with the diff in situ due to dragging effects from the brakes, wheel bearings and transmission internals.

I spoke to an LSD specialist who says the best real world test is to park the car with one wheel on wet grass and see of you can pull away sharply, if you can the diff is good, if you can't and the wheel on the grass spins it is worn.

Interesting though all this is it doesn't answer my basic question;

"do the LSDs in the 964RS click when coming on and off the power when negotiaiting turns" or do I have something else to worry about!

Thanks,
kevin.
 
Yes i have the manual. And i have seen the section in question. I was wondering if any specialist had come up with a way of checking with the diff in the car? I was trying (unsucessfully) to point out the chicken and egg situation that exists. You can't accurately afaik condemn the diff without removing it!
As a point of interest you could probably do the test metioned in the manual by dislocating one drive shaft and applying the test proceedure. Though it would not be anywhere near as accurate due to the other influences you already mentioned.
 
All I can add Kevin , is that my car has never made any such noise , and I've been using it for over 5 years , done 40 k kms and many track days....however I haven't a clue what shape the LSD is in ![8|]
 
John,
Thanks for the reply, caught up with an LSD specialist near castle combe today who has done work for me in the past. He says not to worry, some make a fair bit of noise, including clicks - doesn't mean it's knackered.

Guess I will just enjoy the car and stop worrying - now for the MOT and registration.......
Cheers,
Kevin.
 
Jack one side of the car up so the rear wheel is just in the air. hand brake off and turn the wheel. If it spins as easily as you'd expect a completely free wheel to spin then the LSD is offering no help. If it offers resistance and is stiff to turn then it is doing something. This doesn't tell you excatly how worn or not, but at least you'll know if its doing something or nothing.

On the road: In second gear negotiate a 90 deg junction and lift off. some heavy clonking means wear. Difficult to describe and much easier if you've driven lots of them.
 
You must log in or register to reply here.

Posts made and opinions expressed are those of the individual forum members

Use of the Forum is subject to the Terms and Conditions

Disclaimer

The opinions expressed on this site are not necessarily those of the Club, who shall have no liability in respect of them or the accuracy of the content. The Club assumes no responsibility for any effects arising from errors or omissions.

Porsche Club Great Britain gives no warranties, guarantees or assurances and makes no representations or recommendations regarding any goods or services advertised on this site. It is the responsibility of visitors to satisfy themselves that goods and/or services supplied by any advertiser are bona fide and in no instance can the Porsche Club Great Britain be held responsible.

When responding to advertisements please ensure that you satisfy yourself of any applicable call charges on numbers not prefixed by usual "landline" STD Codes. Information can be obtained from the operator or the white pages. Before giving out ANY information regarding cars, or any other items for sale, please satisfy yourself that any potential purchaser is bona fide.

Directors of the Board of Porsche Club GB, Club Office Staff, Register Secretaries and Regional Organisers are often requested by Club members to provide information on matters connected with their cars and other matters referred to in the Club Rules. Such information, advice and assistance provided by such persons is given in good faith and is based on the personal experience and knowledge of the individual concerned.

Neither Porsche Club GB, nor any of the aforementioned, shall be under any liability in respect of any such information, advice or assistance given to members. Members are advised to consult qualified specialists for information, advice and assistance on matters connected with their cars at all times.

Porsche
Lockton
Pirelli
Officially approved
Oracle Finance
WEX Esso
Collecting Cars
Archant Dialogue
Back
Top