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Can anyone recommend a plan of attack for stengthening the rear half of my TR6 frame with the body on the frame? I would like to lessen the frame distortion and stiffen the whole thing up a bit. No rust or frame rot, just a 32-year-old 16gauge frame on a car that gets thrown around alot. I have seen gussets and the likes in photos but even the TR6 restoration books are vague on just increasing overall frame rigidity. The front has been done with aftermarket pieces, the diff mounts are solid. I just want to make things tighter so that when I jack my car in the wrong place, I can open my doors without them binding. Any old hotrodders out there that work with frames?

Bill
 
Hello Bill,

I drive an extremely stiff TR6, except mine has four doors and is a saloon (sedan), a Triumph 2.5 P.I. . OK, I'm joking a bit but a sports car with a single plane chassis is going to be difficult to match a closed monocoque car, especially one as double and treble skinned as mine is.
What the professional rally preparation people do is to seam weld all spot welds. In fact, I believe they brazed rather than welded them. I think that there is limited gain from gusseting, except maybe to the raised suspension structures.
A much more involved and complicated approach would be to feed the chassis loads into the body, i.e. make that share some of the stress, but would also probably need some deeper sections below the door apertures.
I don't think that many of the Triumph 2000 range were ever imported into America, but to me it is a great sports car even if it has four doors.

Alec

PS, have a look in the photo section, search for 'piman'
 
The only real sucesses at what your trying to do, that I've seen, involve roll cages. That 3rd demension seems to be the key. I'm sure there are more subtle ways to gain more stifness without building up through the body but I haven't seen any documented.
 
Bill,

Just look at it the way I do.. with all the chassis flex, the suspension doesn't have to work as hard to keep the wheels on the ground. /ubbthreads/images/graemlins/smile.gif

Seriously, Revington TR makes an "on body" rear frame strengthening kit for roughly $40.00 if I remember. It includes about 15 pieces of metal that, if you follow the instructions, would GREATLY increase the area where the diff and shocks mount. I ordered it, but I only used the pieces to weld up the diff mount. Since my frame as in such good shape I really thought the extra pieces were overkill.

It's part number:RTR7012-2

I think it took a week to come in from Jolly old England.

Good luck,
 
hello Shannon,

yes, English is a difficult language, but used correctly it is very clear and precise. If incorrectly used it then becomes confusing and open to ambiguity.

I have to say that the general level of English, on this Forum, is very good even if some of your expressions are strange, i.e. "my xxxx is toast"

Alec
 
[ QUOTE ]
hello Shannon,

yes, English is a difficult language, but used correctly it is very clear and precise. If incorrectly used it then becomes confusing and open to ambiguity.


[/ QUOTE ]
/ubbthreads/images/graemlins/grin.gif
 
On my '71 TR6 I had a TR4 Surrey top. Even without the top panel bolted on the chassis was noticibly stiffer. You could not see the doors or dash move like it did before the installation. The rear frame on the Surrey was pretty substantial aluminum as I recall. Unfortunately I sold that car to fund my education.
I don't care for the high roll cages installed for racing. However I would think that a hoop could be fabricated that would provide the desired stiffening but not be intrusive. Something along the lines of a short rear roll bar with the top of the bar just below the level of the panel where the gas filler is located. The structure would need to be anchored to the frame. This would add a vertical plane to the overall structure that would prevent some of the twist in the chassis.
If all goes as planned I will be purchasing another TR6 next month.
 
Thats an interesting idea bobh. Along those lines don't Miatas have a stiffening bar of sort behind the seats along the parcel shelf? Certainly a similar structure could be added to the six.
 
What about tubbing welded withing the confines of the frame rails to cross brace. Tubes are lighter and stronger than "I", "H" or box sections. Flanged on both ends to fit tightly within the frame rails and thoughtfully designed to
add rigidity. I ain't no engineer but seems something could be done or has been done along these lines to stiffen up the frame.

Bill
 
Caveat - it's been a long time since I did any structural analysis, but I think that if you mean adding material (loosely) like a ladder across the chassis, then thats not going to help prevent flex very efficiently - you are adding in dimensions 1 and 2 to try to prevent flex in dimension 3.

Out of all the ideas, apart from a cage, the half hidden hoop sounded interesting. I wonder if you could do something similar in front of the tank so it's hidden from view.
 
I think that if you cut a piece from a thickish sheet of aluminium, using the "vanity" panel that covers the gas tank from inside the boot as a template, and fastened it well, that might help. If it was ribbed that would be even better.
Or I suppose you could just put diagonal bars across to triangulate it.
Simon.
 
I'd think you'd need a half round or half oval, no?
What would you fasten the top ends of the diagonals to otherwise - the body?
 
Hello Bill,

any additional framework has to tie the front of the car to the back, that is the problem, along with the door aperture, which can be overcome with a roof. I think that is why the Stag retained a T frame, although that does little for any twisting moments.

Alec
 
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