Bump Stop

[mike3md]

I recently acquired another 4, and while under the car today I noticed something I hadn't seen before.

 

It seems to be "aimed" at the nose of the diff - and it shows some wear which I assume is from the drive flange

 

It doesn't appear to be listed anywhere, any ideas?

 

Mike

[Bob Smith]

Mike, Is it to stop the axle housing making contact with the floor - seems very extreme though! Not sure if the check straps would contact the axle tube first or after.

[graeme]

Hi Mike,

 

Not sure what year your new 4 is, but the two early TR4s that I have worked on both had this bump stop above the diff. I assume it was deleted at some point.

 

Cheers

 

Graeme

[mike3md]

Hi Graeme,

 

It is a June 63 car CT23129. I can't find any parts reference to it. It must quite an extreme event for it to come into play, and as above I think it actually partly contacts with the drive flange, judging by the "wear" marks on it.

 

Mike

[Motorsport Mickey]

^{Hi Mike,}

 

^{It's to stop the rear axle spring wind up, the axle tube will twist under torque load (as the leaf springs wind up and adopt a S type shape) and the nose of the diff will be it's most extreme point and will move most. Physical limitation by rubber block prevents the UJs having too hard a life (from memory you should try and limit driveshafts within a 7 degree angle of centre line).}

 

^{Mick Richards}

[mike3md]

Hi Mick,

 

That makes sense, although mine appears to partly have hit the drive flange at some time in the past, so quite some wind up......

 

Thanks

 

Mike

[ianc]

A couple of years ago, I mentioned this rubber bump stop, which is fitted to my TR4, to Pete Cox in an e-mail. Although it cannot be found anywhere in the Parts manual, Pete had a number for it, but it seems I have failed to record it.

 

If one hits a monstrous bump at high speed (and it's something which rally cars were prone to do!), the whole axle will travel upwards and both rubber blocks on the outer ends of the axle could be squashed to the extent that this central rubber block may provide the final defence against the axle thumping the floor.

 

Ian Cornish