mark4763 Posted May 22, 2016 Report Share Posted May 22, 2016 Hi , any ideas on how to discreetly stiffen a TR4a chassis to lessen the flex that they all seem to have. Quote Link to post Share on other sites
Alec Pringle Posted May 22, 2016 Report Share Posted May 22, 2016 Rear firewall and a decent roll over bar will add a noticeable degree of stiffness. Cheers Alec Quote Link to post Share on other sites
mark4763 Posted May 22, 2016 Author Report Share Posted May 22, 2016 Cheers, so not a lot to do to the chassis while it's off the car then ? Quote Link to post Share on other sites
stuart Posted May 22, 2016 Report Share Posted May 22, 2016 Obviously you need to do the re-enforcements at the front lower inner suspension boxes plus rack mounts and then the diff pin boxing in and re-enforcing plates on the top mounts for those pins too. That should help. Stuart. Quote Link to post Share on other sites
mark4763 Posted May 22, 2016 Author Report Share Posted May 22, 2016 So nothing extra needed around the T shirt to help to reduce any twisting Quote Link to post Share on other sites
stuart Posted May 23, 2016 Report Share Posted May 23, 2016 If its an original unrestored one then I suggest you take the "T" shirt off as it will be rotten behind it. Stuart. Quote Link to post Share on other sites
RogerH Posted May 23, 2016 Report Share Posted May 23, 2016 Hi Mark, as Stuart mentions, the T shirt area can go rather rotten. It is not water tight on the inside (in fact any side) and there is no protection between the layers. Look at the flat areas of the T shirt and see if there are any humps or bumps. Even the slightest bump will indicate rusting going on. It will be much easier to repair with the chassis upside down. I did it two years ago from underneath and it was an interesting exercise. Roger Quote Link to post Share on other sites
mark4763 Posted May 30, 2016 Author Report Share Posted May 30, 2016 Hi again, thanks for the help so far. How thick should the plates be to strengthen the diff cross member. I looked into buying some but they seemed steep for what you get! Quote Link to post Share on other sites
RogerH Posted May 30, 2016 Report Share Posted May 30, 2016 Hi Mark, not sure the official thickness but I would go for 14 or 12SWG. That should spread the load quite nicely. On your TR4A, have you got the horseshoe bridge that protrudes forwards from the rear bridge section and above the T shirt. - this should give it some good stiffness. The TR6 chassis does not have this. It does have an upper T shirt panel tho'. Roger Quote Link to post Share on other sites
mark4763 Posted May 30, 2016 Author Report Share Posted May 30, 2016 Yes I've got the horseshoe bridge. I was wondering if there was room for any triangulation upwards from the T shirt to help with twist. Although if every body has twist I'm happy to go with it. Quote Link to post Share on other sites
stuart Posted May 30, 2016 Report Share Posted May 30, 2016 (edited) I use 3mm plate for re-enforcings which is strong enough. If your chassis is any good internally then you shouldnt get any twist. I can jack my 4a up on any corner and still open and close the doors no problem after 22 years. Stuart. Edited May 30, 2016 by stuart Quote Link to post Share on other sites
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