Hi all,

Looking for ideas on the cause of gearbox / rear suspension failure.

After a recent track day, on the way home I noticed that I had a very bad vibration at any speed above 30mph.

After closer inspection this weekend I have discovered that the rear aluminium part of the type 9 box has cracked and broken and the two rear lower trailing arm pick up points on either side have failed and snapped the welds and brackets clean off.

I'm looking for reasons as too why the failure would occur before pulling the car to bits.

Locost 7
Zetec 2ltr blacktop 160bhp
Type 9 5 speed
Koln live Axle

I have noticed that the axle has hit the underside of the transmission tunnel, but unsure if this occurred after the failure or was the cause, but I would like to understand why the gearbox snapped?

Any ideas welcome

[Edited on 26/5/13 by Yodaknowscncs]

Not uncommon for the trailing arm brackets to go on a live axle car with just a 3mm U bracket on the chassis tube. When I did mine the advice was to brace them or cut a face out of a 2" box section.

What I don't understand is why the output shaft of the gearbox has snapped

If the axle has been able to move forwards, then has the prop been pushed right into the gearbox and bottomed out?

Yep I'd go with rear suspention failure caused a twist to far and the gearbox tail housing which is normally unstressed aluminium gave up