Drivetrain "clonk"

[stuartgb100]

I'm hoping to fit a new engine/gearbox to my Sprint over the Christmas break, and that'll be the time to narrow down and solve a problem that I inherited when I bought the car, years ago.

That is, an annoying "clonk" as the drivetrain takes it up after changing gear. This can be eliminated by a very smooth (but slow) gearchange.

Changing from rotoflex to cv joints, years ago, made no difference.
A replacement diff and output shafts have also made no difference.

Any ideas, please?

Regards,
Stuart.

[cabc26b]

The 4 mount points of your diff to the chassis it self.

[john.p.clegg]

Prop shaft U/J's?

John

[Jason1]

Gearbox mount??

[miked]

Stuart,

Assume this it only at pulling off and low speed and high loads and maybe 1st to second gear.??????

I have had it happen when the two top anchor bolts (that the diff' hangs on) have worked slack. When you pull off there is clunk. The standard top bush tube is very weak and over tightneing of these nuts can cause the inner tube of the bush to distort and collapse giving slack. I found that some of these hardware kits that can be obtained (Lotus show etc) do not always have the exact size of big 2 inch washers. The inner holes can be metric (larger). They encorage the tube to collaspe and keck over into the larger hole. I fitted two new top mounts and cut my own two inch washers and put exact holes in. You can fit metric bolt in the mounts and these are a snugger fit. I also found that after some miles a creak came back and you can get a bit on the spanner and get rid of it. However, it is fine line between crushing the bush tube. Perhaps TTR top bushes are the anwser, if this is your problem.

I blamed the diff' until I examined the 2 inch washers and inner bush tubes. Also found that they would not stop tight.

These bushes take more stick than I appreciated. They also flex quite an amount even when sound and tight.


I also note on the Sypder chassis (if you have one) that the front clearance on the 2 inch washers is limited (under the cross member) where the spacer washers fit. They foul towards the front. I am told that Spyder now give instructions to grinding flats on the washers then they clear the front cross member. It is a bit of pain as you have to make sure they don't turn when you tighten the assemebly up. On the Lotus chassis there is bags of room as the bushes sit bang in the centre of the sheet steel top hat section.


Mike

[stuartgb100]

Many thanks for the suggestions.
Hopefully will find the culprit over Xmas.

Regards,
Stuart.