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Triumph TR6 - Diff mount repair

Is there any need to strengthen the rear crossmember and/or it's pins? If so, can anyone describe how and what they have done? Any pics?
The pins on mine appear solidly affixed, both at the top and thru the bracket, (unlike the front r/s, cracked).
I've read about welding plates to the top of pins on the crossmember, how about boxing in the channel crossmember itself, would that help?
I'm working on a bare 1970 TR6 frame, and have repaired or strengthend the other infamous weak points and just wondering what others have done?

Also, a inquiry on what others think about boxing of the front diff pins.
Drill holes in the plates for water/air to get in/out, or seal it up solid?
Dennis Silance

The brackets that the pins go through crack at the bottom so it is a simple job to just box it in,but do leave a hole each side so you can inject some rust preventor and it also helps any water to escape.
As you have a bare frame it is advisable to check where the pin is atached to the crossmember,I had to do mine in situ and it was not easy.

Barry Wallbank

Dennis, you're lucky to have a nice bare frame to work on , I did most of the diff. mount arch reinforcing
after the car was asembled and still bare the mig
splatter burns to prove it. Yes, definitely strengthen
the rear arch. It is one of the weakest parts on the
car. Box in the pins iside the channel arch then box in the bottom of the channel. You could also weld on
a 1/4" x 1" steel strap that starts from the bottom on the frame then follows the curve of the rear arch all
the way over to the other side and is welded to the bottom of the frame again. This strap of course is welded to the arch itself as well as the frame. It adds strength and stiffness to the arch. I added this strap because I had heard of a guy who had installed the rear shock conversion kit and after doing some hard driving found that the rear arch had actually been
torn off the frame. Now, whether it was the shock
conversion or his driving or that it was weakend to
begin with I don't know. I took me 20 min. to weld the strap on and my rear arch will never break off.
In addition to boxing the pins on the front arch as well, you could also add some triangular gussets
where the striaght uprights T into the horizontal crossmember. You refer to the other weak points, I assume you mean the front A arm mounting brackets?
Christopher T.

Mmmm - wish I had a MIG....
Brent B

Other weak points found and fixed so far were; outriggers for trailing arms replaced, breast plates upper and lower, reinforcement plates to lower wishbone brackets for front suspension and new pin and bracket for diff mount on forward rear crossmember.

As to the triangle gussets you referred to;
If I understand your thinking, this would strengthen the crossmember where the coil spring fits at top?

Anyone know of any good pics posted on the net of these areas?
Dennis Silance


Check you email, I got this from another member on a different forum.

If you have photos/instructions for these fixes, I'd surely appreciate a set. My tub is coming off the frame next week and I expect to start on the chassis in ernest soon thereafter and want to make very sure that I do all that is necessary before reassembly. thanks. email...douglas.r.bakerATsaicDOTcom. Do the usual with the AT and DOT.
Doug Baker

Mr Deal Very good info for the upcoming CD. Doug If you get this can you forward to me for when I ever plan on a tub off.

great close-up pics of the repairs! Thanx.
Is that 1" square stock in between the two crossmembers?
Is that your car?
Wondering what else was done to rear most crossmember besides plates on top of pins?
Dennis Silance

No that is unfortunatly not my car, but soon will be. I have been stockpiling info for the restoratoin for a year or so and this was one thing I came across. You are correct it is just 1" square stock though. The body and frame are going to the media blaster this month and then the repairs will commence.

As for the rear diff pins, basically just box the entire section with a few hole for water drainage. I even heard of one guy injecting expansion foam into the holes once the repair was made, in order to keep water out.

I am also going to box the entire rear hoop/diff strap as well. I may add some X braces, but not sure yet.

Good Luck

There are some decent shots of my frame work at the following link:

TSI Imported Automotive sells a 6-piece frame strengthening kit that I used, with the caveats noted on my web page

Revington in the UK makes an excellent kit also, which I would recommend if the body is off the frame:

Good Luck, Tom


Tom =-Any Chance you have those frame repairs in a folder to pass along via email?

Doug et al
I have a PIC.DOC of the dif repair plate if interested.
Rick C
Rick C

Great resource for the frame modifications. I will be doing the same in the next couple of months.
I would appreciate any other frame upgrade information that is out there. I already know I am going to need to replace the rear trailing arm mounts and the cruciform on my car.
Tom C

I did up my frame last spring and completed the following modifications that I hope will improve the chassis performance: Replaced trailing arm brackets with shop built internally stiffened units made of 16g steel, plug and fillet welded. Replaced lower cruciform with CNC plasma cut 10g plate, ribbed with 1/4" x 1" bands to match the stock appearance. Internally stiffened between upper and lower cruciform plates with "half moon" gussets. Cut out lower front cross member bottom plate ( a PO had jacked at this point and dented ) and welded in a 2x2x1/4 angle flush with bottom and plug/fillet welded 10g plate in place of the 16g stock frame bottom. All plug welds were faired out to give a stock appearance. Most other welds were ground out and rewelded, main frme components were fully welded up. I then primed and painted(Dupont chassis black ) the sandblasted frame. all new components were weld primed before jointing together. The entire tail section was also fabricated in shop to appear and perform as stock right down to the tow eyes (CNC plasma cut) to finish the body...ugh.

Cheers, Rob 76'6
Rob Gibbs


Out here in the sticks, all we have is dial-up internet access. It would take literally hours to send you a folder of pix. Sorry.

Cheers, Tom

Your ISP rejected the photo files as too large. I sent one as a test yesterday and it did not come back so I'll send the others one or two at a time as I can. Look for a barrage of email next week.
Doug Baker

This thread was discussed between 02/11/2005 and 05/11/2005

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