Broke drivetrain / gearbox while drving...

[Phil-CH]

Hi there!

A mate of mine has a problem with his car. While driving at relatively low speed (less than 40 mph), after changing gear, he suddenly had no power going to the wheels anymore. It's not likely to be the clutch, as engaging and disengaging it can be heard and felt. When disengaging the clutch fully though while having any gear selected, there's absolutely no power delivered to the rear wheels.

My mate noted that the gearbox feelt a bit like pressing against a spring when putting it into gear when it happend. Apart from that though, no noise, explosion or anything that would hint at something severly being broken.

Any ideas what this could be? Drivetrain related or indeed the gearbox? We tried looking underneath the car to see anything (while trying putting into gear, releasing the clutch while having the engine running), but no luck. No funny sounds either. It seems as if at some point, the power isn't delievered to the rear axle and it seems to be somewhere after the clutch.

Any help would be very much appreciated, thanks!

Car in question is a Superlight R500 (with rover engine).

Cheers Phil

Edited by Phil-CH on Sunday 6th September 20:22

[GreenV8S]

Suggest you start by looking to see whether the prop shaft is turning. That will tell you whether it is a clutch/box problem or a diff/half shaft problem.

[BertBert]

mmm, if not the clutch it sounds like a gear selection problem in the 6 speed box. Never heard of a diff do that.

When running in neutral(!) with the clutch not depressed you should be able to hear the chuntering of the input shaft n gearbox gubbins. When you put the clutch in that noise should diminish/go away. That might confirm an ok clutch operation.

I had a couple of similar problems with gear selection in my SLR a few years ago. Once I think it was the bracket holding the gear lever coming undone (just the bolts). Unix the gear lever gaiter and have a look. Another time, I think it was a roll pin in the selection mechanism that came out (box out to fix).

If you rule out the diff as a problem, you are probably facing an engine and box out. Then the box or clutch can be fixed as necessary. Phil Stewart at Road n Race Tranmissions is a good bet for fixing the box.

Bert

[The Wookie]

Does the stick feel like it's engaging the gears? Could be something as simple as the roll pin in the bottom of the gear stick

[Incorrigible]

With the engine off can you select gears ? My first guess is clutch release bearing but it's really difficult to diagnose with the information you've given.

>> I've just re-read your first post and changed my mind. Yes you need to accertain whether the propshaft is rotating when it's in gear

Edited by Incorrigible on Tuesday 8th September 13:40

[Phil-CH]

Thank you very much for the help!

I have relayed the questions and advice to my mate and will post the feedback in here.

For what it's worth - after removing the parts around the gear-lever to get a better look and following some instructions by a mechanic over the phone (closest mechanic is a two hour drive), he's leaning towards the roll pin in the selection mechanism that could have come out.

We'll do some further investigation to single out various factors as pointed out though and will post the results in here in hope that perhaps it isn't an 'engine and box out repair', although that currently seems the most likeliest, unfortunately.

Thanks again!

Edited by Phil-CH on Tuesday 8th September 13:54

[DPX]

Is it forward and rev ?

[F355GTS]

You can do the rollpin with the box in the car, the trick is to stop it happening again, if ti does talk to Phil at Road&Race Transmissions, he does a modification as per the Caterham 24Hr Nurburgring Car which inc. 2 roll pins