SR4 Drive Problem

[jamesrose]

Hi All,

I had a great morning today at Woodbridge, getting to know my SR4 on its first outing with me.

However just before lunch, it suffered a problem with drive to the rear wheels.
Everything was going well, until on a gear change from 2nd to 3rd suddenly there was no go, as though something hadn't engaged properly.

I managed to stop, get back into first and make it back to the paddock, but that was it.

Has anyone heard of something similar to this before, I can't work out if it is a problem with the clutch, gearbox or diff. The rear sproket turns and increases speed with engine revs, but doesn't seem to drive to wheels !

Any ideas ?

[Matt Graham]

If the rear sprocket turns, and increases speed with engine revs, then your clutch and gearbox are OK.

Check for a broken axle (half shaft), CV joint, or hub.

Failing that, there may be a problem with the diff, or the bolts that attach the sprocket to the diff, although either of these being the cause are unlikely.

-Matt

[jamesrose]

Matt Graham said:

If the rear sprocket turns, and increases speed with engine revs, then your clutch and gearbox are OK.

Check for a broken axle (half shaft), CV joint, or hub.

Failing that, there may be a problem with the diff, or the bolts that attach the sprocket to the diff, although either of these being the cause are unlikely.

-Matt

Thanks Matt, I think it must be a problem with the diff then as everything else seems ok...sounds expensive !

[splitpin]

YHM via Will @ ROC

[yellowrad]

If its one of the early type SR4 diffs with the 4 planet gear sets I wouldn't be surprised if you have bust them, the later ones have 8 planet gears and don't break.

I had the same problem - get your cheque book ready if that's the cause!

Good luck

[jamesrose]

Thanks, that sounds about right !

Can these diffs be rebuilt or repaired is a a whole new unit needed ?

It is an early SR4 with reverse.

Edited by jamesrose on Sunday 5th April 22:31

[RobC]

Its a Ford unit iirc, you could just send it back to Quaife for a service (don't mention the "R" word though )

[BertBert]

sounds like when I dropped a cog in the gearbox
bert

[BertBert]

but then again maybe I didn't read the post well enough!

[yellowrad]

Yes, they can be repaired. You would have to do it through Radical though. They send them back to Quiafe. Approx. cost is a grand

[jamesrose]

Ok thanks, thats pretty much what I was expecting.

[RobC]

A grand! blimey, take it to a decent machanic/gearbox chappy, they are not complicated by any strech of the imagination. The standard ones (i.e. without reverse) are £550 new from Quaife.

[DarcySmith]

James,

The unit will have to be returned to Radical to be repaired.
Whilst it is there,ensure it is upgraded to an 8 pinion set up.
The diff itself is easy to strip and repair,but Quaife will not sell those parts to anyone but Radical.

Its a grand to get it fixed

Darcy

[nick997]

James, hope you had a good day out despite the problem. The runway part of the circuit will have given you a bit of an idea what these cars are capable of... Hope you can get it sorted for Silverstone.

What are the thoughts on reasons for this type of failure - Woodbridge was very bumpy which can't have helped.

[jamesrose]

nick997 said:

James, hope you had a good day out despite the problem. The runway part of the circuit will have given you a bit of an idea what these cars are capable of... Hope you can get it sorted for Silverstone.

What are the thoughts on reasons for this type of failure - Woodbridge was very bumpy which can't have helped.

Hi Nick, Good to meet you, yes I had a great morning. I have driven some pretty quick road cars before, but there is no comparison to the Radical.

On a seperate note about the diff - Is there any reason why I can't replace the reversing diff with a normal forward only one...The reversing one is twice the price and from what I have heard so far no one uses reverse anyway !

Edited by jamesrose on Tuesday 7th April 12:25

[nick997]

You need a reverse to race which I think was your end goal.

Yep, forget about fast road cars, too big and heavy compared to Radical's.

[splitpin]

nick997 said:

You need a reverse to race which I think was your end goal.

Yep, forget about fast road cars, too big and heavy compared to Radical's.

And let's not forget about all those bloody so called safety cameras that totally stiffle one's enjoyment of such cars 99% of the time!

I did suggest JR give me a call as I thought at one time I might be in for a new diff/gearbox but wasn't ...... oh well