Cleaning my Chummy down after the Welsh Trial I have found that I have cracked one of the chassis rails just in front of the front cross member. I have read various bits of conflicting advice regarding whether to plate ove the crack - which can lead to cracking in the un-reinforced areas - and what sort of welding to use - MIG or TIG. Any thoughts/advice/experience?

Thanks

Guy

If you know anyone who has access to the Vintage Alvis Manual there is a good section in there on chassis repair. Regret unable to consult nearest known copy (40 miles away!)

Regards, Stuart

Guy

No experience of my own I'm afraid, BUT The Modern Motor Engineer Vol 3 gives an explanation as to how it was done years ago before modern welding techniques were available.

It is advised to not just weld the crack due to the undesirable effects of the welding process on the metal of the side members. It is recomended to weld the crack and then fit a reinforcing member into the "U" channel, i.e a section of channel smaller than the existing channel fitted tightly in the "U" This reinforcing section should be rivetted and can then be welded at the bottom.

This is of course very old information so may not be relevant to a modern repair situation? Incidentally the book is full of interesting old repair techniques a real goldmine! from ebay at a sensible price!

Steve

That's bad luck Guy - given that we both finished on the same number of points on the Welsh, perhaps I should check my chassis as well!!

I do have a crack in the chassis of my LeaF that has been there for a long time. It's plated over but the plate is bolted, rather than welded and it hasn't 'grown'. Whether such a repair would withstand the abuse we subject our Sevens to is open to debate. Alan Bee has, however, MIG welded the chassis (and also the nose piece I think) on his trials Chummy to repair similar problems in the past if I remember correctly.

See you on the Lakes?

STEVE

My 28 Chummy had both chassis rails cracked completely through in the same position as yours. A previous owner had bolted a piece of ash inside of each rail with 3/8” bolts. When I bought the car in 1975 the bolts had worked loose and all that held the car together was the fact that the engine was resting on the bulkhead panel! I made up two channels out of 1/8” steel plate about 15” long and fitted them inside the chassis rails and welded inside of the bolt holes that had fixed the ash, virtually big spot welds. When this was complete I then welded around the crack after first having ground a ‘V’ in the crack. No further problems have been found since (twenty thousand + miles to date). With the present state of the roads around Bristol, they have had a bashing, but have not done any off roading.

I will have to reference my copy of the Modern Motor Engineer - I have a copy from the early fifties that I have forgotten to look at.

Steve, yes the same number of points - just outside the awards - we'll have to try harder next time. I think that I am just going to have to get my welder out and give it a go. I will not be out on the Lakes - particularly as the body is off at the moment - but I was aiming to try an get onto the Cotswold.

Re Ian's suggestion I think this may be the way to go. I may well taper the ends of the channel so that there is no sudden change in stiffness that causes a stress concentration and hence cracking.

Guy

Yes Guy, I failed to mention that I put a four or five inch taper at each end of the channel, it all looks very neat and is difficult to spot. I think because it is not welded around the edge the stresses are dissipated.