Rear end knock and noisey rear diff

[Toby S]

I've recently bought a 1993 1400 K 16v Supersport as my first Caterham with 26.000 miles. Thoroughly loving the Caterham experience especially the exhaust note and acceleration (particularly when you're above 6,000 revs !!)

Having been used mainly as track day car for around 10+ years and doing around 6,000 miles in that time, there were a few things to do to get it through it's MOT, although these were fairly easy and it flew through after only a few weeks work.

One thing I've  noticed having now done around 800 miles myself in the last month or so, is the a whine from the rear (diff I think) on deceleration and a clonk coming from the rear when going from deccelaration to acceleration. The car is fitted with an APST limited slip diff (fitted by Road and Race in 2000). Don't know if the diff oil has been changed, but given the mileage would guess not.

I've been underneath and checked the A frame and suspension fixings and these all seem to be sound (no movements and torques seem OK), so guess it must be linked to the rear diff. No obvious oil leaks, albeit the diff itself is a bit grimey - dif seems to be working OK (both wheels run together when both off the floor),

Questions:-

1. Am I on the right track, or could it be the suspension bushes (currently ruled out as no movement in suspension supports and the car seems to handle fine)

2. I hear whining diffs are not uncommon especially on LSD's - but what about the clonk

3. Would changing the diff oil improve matters - if so any recommendations as to grade of oil - also if so where's the drain plug (all seems a bit tight around the back, and I can't even find the nut for checking the oil level).

4. Finally - and probably the case !! - Am I just a newby previously used to driving in more cosseted (quiet) environments and there's nothing to worry about - just one of the joys of Caterham ownership.

Any thoughts welcomed

[Jonathan Kay]

I can only help with part of 3, and even this may not be appropriate for your diff:

1. There often isn't a drain plug. But you can suck it out, easier when warm.
2. Maintenance notes for this (and other common tasks) from Alcester Racing 7s.

Jonathan

[john aston]

Almost certainly TADTS . When I got my first Seven (a 1.4K SS from 93 too ) I was convinced it was about to expire. The whines worried me and the clunks and bangs alarmed me- at least for the first couple of thousand miles. About 70 k miles of Sevening later I don't worry - my current car banged and whined and whirred from new in 2007 - as did every other Seven I've driven.   

[SM25T]

Hearing protection will help you worry less and save your hearing. It is a must.

[cr500dom]

I`d be letting R&R take a look inside that, if it was last looked at 16 years ago......

Yes they are all noisy to some extent, but I would rather have it refreshed and reset, than be shelling out for a full rebuild of the diff with new Crownwheel and Pinion.

LSD`s are a servicable item too, they have clutch plates that wear, they are not totally "Fit and forget"

[7 wonders of the world]

Toby,

Your within spitting distance of Steve at SP Components in Redditch ,

He will advise on a repair whilst he strips it in front of you - and the rebuilt unit will be done properly and silently - you wont find better.

http://www.tracsport.com/

 

 

[Roadsport06]

Yes, has to be Steve, just down the road.

[Toby S]

Thanks for the advice guys

Given the closeness - SP Components seems a good call which I'll try

Probably also worth going to the next area meet to see if I can get someone to listen first hand and see if they think the noises are normal or odd