BritishV8 Forum

I came across this website on restoring a TR6 and they welded up the frame in a most unusual manner.  The website was in German so I could not read any of the text.  Check out the attached photos.  Will this configuration make the frame stronger?  I see a real problem with moisture getting between the floor pan and the frame reinforcement.  If there is any advantage in making the frame stronger with this method I guess you could put in a bunch of drain holes to counter the moisture issue.  
I just thought I would run this by you guys to see what you think of this method.  Don't get me wrong on this I am not planning on doing this!!!





Cheers
Byron

What the TR6 frame mostly lacks is torsional rigidity and as much as those plates may stiffen the rear section, that isn't where the strength is most needed. IMHO

JB

The idea of adding a thin "stressed skin" to a frame is generally good. You'll see stressed skins on lots of spaceframe based racecars from the early seventies on. The areas you see "skinned" in the photographs are basically trapezoidal, and when a load (e.g. engine torque) is applied at one corner, the whole trapezoid is inclined to lose its shape. I guess you could say that the stressed skins act like great big - but lightweight - gussets. If a skin on one side is good, perhaps a skin on both sides would be even better.  To avoid corrosion issues (and heat caused distortion/stress) this guy could have used a structural epoxy. (The skins could have continued over the top surface of the frame tubes to facilitate this.) With epoxy, galvanized steel, stainless, aluminum, or a structural composite might possibly have been substituted for the plain steel skins. When racers use adhesive to apply a metallic stressed skin, they typically also use pop rivets. The rivets are nowhere near as strong in shear, but they hold the panel in place nicely until the adhesive cures. (Most adhesives are strong in shear but weak in "peel".) You could also make a case for soldering or brazing on steel skins instead of welding. Are you familiar with gas shielding gas for brazing torchs? Expensive, but good!

Isn't that Megatron from the transformers?

If you want to glean more from the German website, I have been told that the Google translator for German to English is much improved.

you can also download babel fish to translate text, last i looked it was still free but its been a little while. Most online translators translate word for word so you kinda only get the jist of it, but it is helpful.

There are a lot more effective ways to strengthen a frame. If that thing gets twisted, will it come back? It would be pretty discouraging to here a loud "POP" under seat.

The first thing my machinist friend said when he saw my TR6 frame was that the rear section needs to be reinforced right in front of the rear wheels.  I agreed with him as I had thought about this for quite a while.  So I decided to mock up the reinforcements with .25" MDF.  The brackets will be laser cut out of 3/16" plate and will be welded in place.  I have looked at this from all angles and I think it will work.
The gap between the bracket and the swing arm is 3.5" being that this possible point of contact is only 2" away from the swivel point for the swing arm I highly doubt that there will be any contact.
I put the seat in and and pushed it  back as far as it would go on the track and the where the bracket comes through the floor it is behind this point.
The only down side of this is the work to box in the slots in the floor.  I would like to get some feedback on this before I proceed any further.  I have attached some photos for your viewing pleasure.
Thanks

Rather a novel approach to be sure, and one that will certainly strengthen the LCA pivot box and the spring perch as well. 3/16" thick material is overkill though, 1/8" should be more than adequate and .093" would do just fine.

JB

Byron,

I like it! I agree with Jim - since the tower is made of tissue paper 3/16" is overkill.



George

Thanks Jim and George for your comments. I agree that 3/16" is overkill so I will go to 1/8".  I prefer staying with thicker material as my welding skills are not there for using thinner material.  
For anybody out there that would like to do the same just contact me and I will e-mail my drawings.  I am sure every frame is slightly different so what may work with my frame may need to be tweaked with another frame.  I will probably work up drawings for the sheet metal enclosures as well. Sigh more work now!!

Can you supply the link to the German web site? I can sort of read German....

The suspension geometry is most affected by the stability of the trailing arm pivot points. Flexing of the spring seats mainly affects roll resistance (which is important also). I like the approach to run braces from the trailing arm supports to the spring seats because it adds a three dimensional element to an otherwise flat frame.

Larry I stumbled across this link when I googled TR6 and clicked on TR6 images.  I randomly clicked on this one image of a silver green TR6 and it was this German website.  I have tried many times to find it again but have had no luck.

Byron, Did you proceed with your bracing modification between the LCA pivot box and the spring perch?  It looks to be the best frame stiffening remedy I have come across!  What were your results?
Also, did the modification to the body interfere with the seat travel?  Would love to see a picture.  
Thanks,
Rob

Rob I reinforced the frame with struts that I fabricated out of 1/8" mild steel.  Boxing in the cutouts were a bit of work. I boxed them in after the tub was mounted and shimmed as this area undergoes a lot of flexure.
I used glue and pop rivets to construct the boxed in sections.
Right now I am doing the upholstery and these boxes do present a little bit of a challenge to work around, especially for the vinyl that goes on the wheel wells.
I have driven the car and the boxes do not hinder the seat movement at all.
For anyone who is thinking of doing this the first thing to check is whether the frame has drooped at the back.  A good indication of this is the door gaps at the back are wider at the top then they are at the bottom.
To check for droop level the car so the frame is parallel with the floor.  Now measure from floor to the underside of the frame in front of the wheels and do the same at the very back of the frame.  Subtract these two measurements and the difference is the "kickup" of the frame.  On a good frame the "kickup" will be close to 4.5".  a frame that has drooped will be less.
If the frame has drooped it needs to be taken to a frame shop and straightened.  Then it needs to be repaired by the t-shirt area.  
Having done the above you can then put in the frame struts.  I discovered this the hard way.  I did not know about frame droop and put in the struts then repaired rust at the t-shirt area.  It was when I put the tub back on and tried to shim it that I discovered the my door gaps were awful and the only way to fix them was to weld hanger wire on my door edges.
It is odd why Triumph built frames with this inherent weakness in the TR4A -TR250-TR6.  Not good engineering!!




Cheers
Byron