Play in LSD Diff

[Clay Head]

My LSD diff is the standard Caterham one and I have noticed that there feels as if there is some play in it. By that I mean if you pull away and back off there is a clunk which comes from the diff. Its mounted ok, prop shaft feels ok, drive shafts feel ok. If you jack the car up and rotate one rear wheel to and fro quickly the play in the form of a knocking sound is apparant. Is this normal or can I remove this by adjustment

[Peter Carmichael]

Depends on which LSD you have. If between ~96 and ~99, you probably have an AP Suretrak. This diff clonks and there is no adjustment that I know of. It is not a problem.

 

The clonking comes about from the torque sensing gears and bits inside this very clever diff.

[allegro]

I don t know about the clever bits, but Ive had this problem on a De dion 1700 SS, a superlight and now on a superlight R. This is not a problem and obviously very common, but on each occasion Ive taken the car to Caterham at Dartford and they have tightened up the dif and almost elininated the knocking. There must be adjustment, but don t ask me where.

Len Unwin fixed it the first 2 times and Simon (in service)had the R adjusted.

 

Andy Mac

 

 

[Rob Walker]

The only adjustment on the AP suretrack is the adjustment for backlash in mesh between the C&P. The ZF plate diff can be adjusted on preloading of the friction plates as well as backlash. A lot of backlash can cause a clunk when taking up drive and transmission shunt when moving slowly in a high gear. Phil Stewart of Road and Race will sort you out.

[Clay Head]

My diff is the Ford LSD in a 1990 car. Any further ideas?

[Andrew Russell]

Just a thought but it might be worth your while checking the hub nuts on the outer end of each drive shaft. If this is even the very slightest bit loose you will get some noise and 'shunt' transmitted through the drive train.

 

Cant remember what size or torque, but big and loads seem to stick in my mind. Also remember that they are 'side-threaded' as I recall.

 

Andrew

 

Edited by - Andrew Russell on 11 May 2001 11:40:51

[Rob Walker]

Tim,

Ford LSD thats the ZF. Jack up the car and check the backlash by holding the flange where the prop connects and one of the wheels. There should be only be a tiny amount of backlash .010" is about right.

[Chelspeed]

What exactly do you mean by "the Ford LSD"?

 

If you mean that it's in a Ford Sierra ally outer case (and it came from Caterham as a standard part) then it could be either a ZF plate type or an AP Suretrac inside, depending on delivery date, for 1990 it would be the latter I think.

 

If you mean it came from a Ford in a scrapper then it's more likely a viscous type LSD, as these were the only lsd's fitted by Ford as standard to the Sierra's that are donors for the 7 1/2 diff used by Caterham.

 

If you mean it came from Caterham but in a Ford package then I can only say that my ZF plate type diff came from Caterham packaged like this for my 1993 car. Always thought that was odd since, as above, Ford never supplied Sierra's with a plate type lsd. Not sure how the AP suretrac diffs were packaged.

 

Hope this helpful - sorry but I don't have a clue about backlash - my only contribution would be to keep driving it, if it gets worse then it'll be easier to find, if it doesn't then what the hell - keep driving it some more.

 

[Chelspeed]

Sorry misread the date on your posting - if it's 1990 then it's more likely the ZF plate type not the AP.