MTFCA Forum

........that is the question!

Now that my engine rebuild is almost complete, it's time to think about a speedster frame. My plan for lowering it (around 5") is to use a square tube front cross member that will enclose the spring at frame rail height. The rear will be two simple brackets that will lower the rails an equal amount. Now the question....

What is the general opinion about welding on the T frame? There seems to be two separate camps of thought on this, one of which saying that the heat will destroy the "special steel". The other side says no harm will be done.

I don't see why modern welding will harm anything. Henry's steel was probably quite good, but I'll be those rails were pressed cold and all holes punched. If anything, welding heat might soften (anneal) the steel a bit but it's certainly not like heating a treated material such as a knife blade. On top of that we've seen many trailers, etc. welded up with no ill effects.

So, will welding do any harm?

George, when I Z'd the rear of the frame for my speedster, I cut the rails at angles and mitre jointed them before welding. In addition, I made plates to the profile of the Z, and riveted them in place n the inside of the frame rail. Overkill perhaps, but it appealed to my senses. I followed the same principle when welding two frames together to lengthen the frame for my 17 shooting brake. It is a neat way to finish off with and I have seen like work on period cars, and on our 1980 Leyland tandem drive truck.

Allan from down under.

You can weld all you want on a T frame, it is good steel even by modern standards. The important part in modification is the engineering of those mods. That is the safety issue.

Just be careful not to reinforce the weld joints too much, Allan's approach is very good if you think you need some extra support, in my opinion. Whatever you do, DON'T make the mistake of "boxing" the joint area. That in effect makes the frame a rectangular tube that WILL NOT flex as the frame twists. That will lead to cracks in the frame at the ends of the boxed area, not if, but will. Dave

Thanks everyone...and I'm aware of the dangers of creating stress areas by stiffening the frame. They were MADE to twist! In fact, I was offered a complete speedster frame, but it was boxed for it's full length so I turned it down. As long as the major portion of the rails are allowed to flex it should present no danger.

I believe in bolts & rivets. Welded frames are yuck. And very very difficult to get legal in my country.

Kep, nothing wrong with welded frames, as long as they are done correctly. I've lengthened and shortened many truck frames from 2ton "farm" trucks to semi tractors with high tensile steel frames. Never had any problems. The trick is not to overthink it and make the joints too stiff. A few years ago I watched a show on TV where they shortened a long wheelbase '70's era Chevy 1/2 ton pickup to a short wheelbase. Yep, they boxed the frame at the joint area. I wish I could have contacted them, but it was a rerun. Makes me wonder how many unsuspecting guys and gals were led astray. Dave