View Full Version : TR6 TR4A IRS body on a TR6 Frame?? Differences?

04-08-2012, 08:37 PM
Hey guys- I'm currently restoring a 67 TR4A IRS that has very rusty floors, and a really rusty frame.

My Dad gave me a completely rust-free '72 TR6 frame years ago, which I have now completely restored -- bead blasted, POR15, all new suspension bushings, new bolts, etc. It is now sitting on its suspension and wheels. I have the rebuilt TR4A engine almost ready to bolt into the frame, so this weekend I decided to finally get the TR4 body off of its old rusty frame.

Putting the new frame next to the old one, I'm seeing many more differences than I expected. Looks like the radiator mounts are a few inches farther forward (which I expected with the longer tr6 motor). Also, there is a tall "hoop" structure in front of the diff on the old frame that I had always assumed was part of the body. TR6 has none of that.
I also noticed that there are 2 additional body mounts aft of the B post on the TR6 frame.

The TR6 frame is obviously stronger judging by the gussets on the front suspension pickups (which broke on my TR4A) and also in the center T shirt area boxed on top. I also gusseted the diff mountings while the frame was in bare metal.

Question is: Will the body bolt on with no modifications? If so, what should I do about the rear body mounts that the body does not have? Should I worry about moving the radiator rearward to its standard position? I'm not a total purist, but I have been planning this restoration to be very original down to the nut and bolt, but obviously there will be some discrepancies in the frame... Any thoughts?

Would post a couple of pics, but can't figure it out on this site...

Simon TR4a
04-09-2012, 08:47 AM
Welcome to the best site on the net for lovers of British cars!
As you have not yet received a response I will go first and offer a few thoughts.

First: I am glad to see another Triumph go back on the road to be driven and enjoyed by an enthusiastic owner, and glad you are committed to doing as good a job as possible.

Second: What you are doing is a rebuild as opposed to a restoration and even aside from the issue of using a chassis from a TR6, the finished car cannot be referred to as "original", some people get wound up pretty tight about this.

I would suggest you might try to swap your rebuilt TR6 chassis for the correct TR4a chassis if possible, but if not I would avoid modifying the body to suit the chassis.
To remove and replace the floor panels it is probably easiest to brace the door openings of the body very strongly and mount the shell on a rotisserie. Make sure you do one side at a time.
I think I would move the radiator to the correct position, but others may have other ideas.
There are some good restoration threads with pictures that are worth looking at, and I believe a Triumph club in Detroit you might contact.
Good luck!

04-09-2012, 09:43 AM

Are you saying that the TR6 chassis will devalue the car? According to Bill Piggins resoration guide, he suggests strengthening all of the areas that Triumph did on the TR6. My plan was not to modify the body any, just replace the floors as you suggest... Are you suggesting that the body WILL need modification to fit? I would rather modify the frame to look more like the TR4A, as I can't see starting over again with another chassis after having one this good and rust-free. I know how hard they are to find, and how expensive they are once you find one.

04-09-2012, 11:46 AM
I asked the same question some months ago and got a very helpful reply from EpiCenterBryan, who provided a detailed list of the issues he dealt with. Search for post #794419. If you have any more specific questions I expect he can help.


04-09-2012, 01:34 PM
This is the post
https://www.britishcarforum.com/bcforum/u...rame#Post795056 (https://www.britishcarforum.com/bcforum/ubbthreads.php/topics/795056/Re_TR4A_on_a_TR6_Frame#Post795056)

04-09-2012, 01:48 PM
Thanks, Don- the search didn't work for me. Appreciate the link!

04-09-2012, 03:09 PM
I cheated.
I look him up in the member list

04-09-2012, 03:57 PM
Oops! Sorry, next time I'll know to post the link.


04-09-2012, 04:57 PM
No biggie, Tom

Simon TR4a
04-10-2012, 08:11 PM
That seems like an excellent "how to" guide if you decide to go ahead.

Yes, using the TR6 chassis will reduce the value of the finished car.

I appreciate that it is not easy to find a good TR4a chassis, so makes sense to use the chassis you have. My comments were more in reference to your statement " I have been planning this restoration to be very original down to the nut and bolt" more than anything else.

My own car, pictured in my avatar, has had the diff mounts boxed in for strength.
Enjoy the project!

04-13-2012, 08:34 AM
If you are really trying to be original, you could sell your TR6 frame to someone restoring a TR6, (There should be plenty of need for it) and buy a brand new frame from RATCO. I understand they can build a frame to original specs.