Live axle questions

[Graham Howard]

My self built live axle car has covered about 250 miles from new. A 'clonking' sound has started from the rear on pulling away.

 

Getting the car on axle stands I noticed some oil coming out of the diff, not sure where, and finding its way on to the 'A' frame bush. The bolt holding the 'A' frame to the axle needed about 2 turns to get it back to the 40 lb-ft torque. The other bolts on the rear suspension also needed re-tightening.

 

I have heard of various problems with the Ital axle, is it normal for the diff to leak some oil? And is it normal to have to tighten the suspension bolts so soon after assembly from new components? I have only used the car on the road so far and it has had a post build check at Caterham where they presumably checked the torque of the suspenion bolts.

 

Any advice would be much appreciated.

 

 

Graham

 

 

 

 

 

 

 

 

 

 

[stevefoster]

on the 2 live axle cars I've had the bushes lasted max 3000 miles.

Make sure that you have not overfilled the diff for road use.

This caused mine to dribble and accelerate the bush decompsition.

You can get more exotic bush materials that are said to last longer. I have never tried them! One was talked about in LF in 98 or 99. Ask someone like James W or the 7 workshop and see what they say these days.

 

As for the bolts. Yes, they may well need tighening. Make sure you use the torque wrench again so as not keep tightening whats really ok. As part of a 3 monthly check a tightness test is a good idea and before and after any track day of course

[Eugene]

The clonk is usually because the rubber within the A frame mount has erroded. The only sure fix is to replace the bushes. Tightening the bolt will only be a short fix as it accelerates the errosion. Take it from someone who has covered over 100,000 miles in an Ital axle 7. Replace the bushes on a regular basis. I always carry spares and can change the bushes at the side of the road in a few mins. The oil leak maybe from the diff but is probably from the breather.

 

Small Boy - with Big Toy!

[Graham Howard]

Thanks guys.

 

I have subsequently checked the oil level in the diff, and yes I seem to have overfilled it, probably because I filled it with the rear of the car high on axle stands.

 

I'll get myself a stock of bushes as well.

 

Graham

 

 

[Robster]

Have read your replies with interest...can anyone comment on this:?

 

My Ital axle did the same to its bushes..clonking every 2000 miles or so...no problem as I changed them. Then, I bought an ital axle fitted with a LSD, and have not heard a sound from the bushes in a year (5000 miles or so). I will change them as a precaution, but I suspect that the alignment of the bracket may be better on the new axle, extending some of the bush life...unless anyone has any more ideas!!

 

 

[Graham Sewell]

I had a similar experience when my car was rebuilt - in 10,000 miles I have replaced 3 sets of perfectly good bushes because once I had removed them to check, it seemed pointless not putting new ones back in.

 

before that, a good 500 mile blat would wear them out:-(

 

Cheers,

 

Graham

[tgracing]

Just a point on bushes. It's not advisable to put hard wearing bushes in as they are a deliberately weak (and cheap) link. If you put hard wearing ones in, something more expensive may break...

 

Davebo.

C7 CAR.

[Nigel Riches]

Graham, I got fed up with replacing diff bushes several years ago when the diff bracket broke off the axle, I took the axle back to Caterhams, and whilst waiting for the new bracket to be welded on, got talking to one of the sales guys who said that a rose jointed "A" frame was available and being a sucker for new bits for the car I bought one, never changed a bush on the diff since, the big down side is the price of replacement rose joints, as nothing lasts for ever, don't know if they are still available and I seem to recall some arguments for and against in low flying several years ago.

Regards Nigel.

[Randal Tarn]

I am not sure where we are here with the original question on the "clonking".

But if replacing bushed has not cured the problem.......

 

Exactly the same happend to my classic after around 150 - 200 miles.

The reason on mine was the flange bolts joining the prop-shaft to the diff

had slackened slightly.

 

A quick re-tighten and the clonk was gone, and has not reappeared after 2,500 miles. (Unfortunately you don't find out the cure is that easy until you have tried everything else.

 

Hope this helps.

Randal.

[Graham Sewell]

Or at the other extreme, I started with a clonk as I went over pot-holes (I hate London roads) which was initially diagnosed as wheel bearings drifting in the axle tubes. So new bearings and the Classic Carriage fix (aka shims to locate the bearings). This didn't fix the problem, and it was noted that there was some play between the half shafts and diff - so diff repaired.

 

Picking up the car tonight (after 4 weeks), hopefully it won't go clonk anymore.....

 

Cheers,

 

Graham