RogerH Posted July 19, 2014 Report Share Posted July 19, 2014 Hi Folks, as some of you will know I have the gearbox out at present on the 4A whilst it and the overdrive are refurb'd. I decided to give the chassis a clean and a once over. All was well until I came to the breast plate (T shirt) that joins the chassis rails in the middle. There was a small Vesuvius sitting on top of a swelling on the plate in conjunction with a flat area of chassis rail on the nearside rail. I decided to do some keyhole surgery to see the extent of the chaos - sadly an angle grinder doesn't do keyhole very well. Significant rust is present from the rear weld to apprx half way forward along the plate. The lower face of the chassis rail has thinned in a small area and there is a small hole in it as well. The offside rail looks good. Question 1 - Do I remove the breast plate and clean every thing and fit a new plate? Qustion 2 - Do I simply stick a patch over it (not my preference) Thinking about this area - the breast plate is welded on many edges to hold it together but is not truly sealed form the atmosphere so rust WILL happen. Question 3 - Would it be worth having holes in the lower surface of the chassis rail to allow waxoyl type stuff to get into the cavity Question 4 - Are there any major problems in fitting a new breast plate. Will the chassis fly apart when I cut through the welds. Roger (whatever next) Quote Link to post Share on other sites
graeme Posted July 19, 2014 Report Share Posted July 19, 2014 Hmmm, sounds like a full body off restoration coming up. Better get that 4 on the road first. Cheers Graeme Quote Link to post Share on other sites
RogerH Posted July 19, 2014 Author Report Share Posted July 19, 2014 Hi Graeme, that thought did flash past me. The breast plate doesn't look too onerous (oh yes it does). A day to remove and tidy and a day to refit (by the way the price of petrol is coming down £1 a ltr) I really need some knowledge on the best way forward. Roger Quote Link to post Share on other sites
RobinTR6 Posted July 19, 2014 Report Share Posted July 19, 2014 Roger, oh dear again its getting worse. Can't advise I'm afraid as I'm no expert. FWIW when I did my 5 and got the body off the upper breast plate had rusted thru , and it all looked perfect from the underside. Is the top one ok.....? Quote Link to post Share on other sites
RogerH Posted July 19, 2014 Author Report Share Posted July 19, 2014 Hi Robin, the 4A only has a lower plate. Roger Quote Link to post Share on other sites
Peter Cobbold Posted July 19, 2014 Report Share Posted July 19, 2014 Hi Robin, the 4A only has a lower plate. Roger Ooh...er - I would not cut through it !! Dont actually know what will happen, but I imagine the two rails wont stay put. Tops of the rails may well have rusted through, in places, where the floor hides them. I had many small holes to patch up there on the 6 despite years of waxolying. I'd weld braces across the top of the gap before cutting and patching the cruciform. But I dont think I'd let the two sides part company Peter Quote Link to post Share on other sites
RogerH Posted July 19, 2014 Author Report Share Posted July 19, 2014 Hi Peter, that is what was going through my mind. It is braced at the gearbox and at the rear cross tube under the boot. I could easily weld a brace fore & aft of the plate. Roger Quote Link to post Share on other sites
AlanT Posted July 19, 2014 Report Share Posted July 19, 2014 The only hard thing about this is that its hard dirty work, all done upside down, on your back. Quote Link to post Share on other sites
JJC Posted July 19, 2014 Report Share Posted July 19, 2014 Roger - for what it's worth (from a non engineer) we did that job on the 6 many years ago without taking the body off. Replaced trailing arm supports as well. it was fine. Now I have the body off and can see the repair was perfectly good. Good luck. JJC Quote Link to post Share on other sites
RogerH Posted July 19, 2014 Author Report Share Posted July 19, 2014 (edited) Hi JJC, did you have to brace the chassis rails when the plate was removed.? Roger PS - did you use MIG or Arc welding? Edited July 19, 2014 by RogerH Quote Link to post Share on other sites
ianc Posted July 19, 2014 Report Share Posted July 19, 2014 Why not bend Colin Matthews' ear? He's a helpful sort of chap. Ian Cornish Quote Link to post Share on other sites
RogerH Posted July 19, 2014 Author Report Share Posted July 19, 2014 Hi Ian, that is far too sensible. I'm sure the collective knowledge of this wonderful encyclopedia we call the forum will come up trumps. Roger Quote Link to post Share on other sites
AlanT Posted July 19, 2014 Report Share Posted July 19, 2014 On the underside I'd use MIG rossette welds, with elonated 5/16in holes, 3/4in apart. An inner row and an outer row staggered. About 3/8in from the fold. You will want quite a high current and it will tend to run into blobs. I spaced mine at 1in, but I had the chassis clean and upside down. It would also be good to do some fillet welds on the top side in the tunnel, This assumes you use a pattern part `T-shirt. If you are prepared to make one you could fold the edges and weld on the vertical rather than upside-down. Quote Link to post Share on other sites
RogerH Posted July 19, 2014 Author Report Share Posted July 19, 2014 A plan is forming. I'm going to get dirty. tired, burnt, possibly set the car on fire. What the heck. Roger Quote Link to post Share on other sites
AlanT Posted July 19, 2014 Report Share Posted July 19, 2014 Fix the T-shirt in place with self-taps before welding. Quote Link to post Share on other sites
RogerH Posted July 19, 2014 Author Report Share Posted July 19, 2014 Hi Al, I've got some nice 1/8" skin pins. They should hold it tight. Roger Quote Link to post Share on other sites
AlanT Posted July 19, 2014 Report Share Posted July 19, 2014 (edited) Have you got room to drill upwards under there? Edited July 19, 2014 by AlanT Quote Link to post Share on other sites
LGFromage Posted July 19, 2014 Report Share Posted July 19, 2014 Hi Roger, It is high time you had some good luck but it is reassuring to remember that other people get problems with their TRs. As for your query 1 and 2 I suggest removing the plate having braced the chassis to prevent any movement and install a new one. You would not be happy with a patch. Query 3: The chassis in my TR has holes drilled (and fitted with rubber bungs) for waxoyl and this has proved to be beneficial so could be helpful for your car. Query 4: Welding underneath can be a pain particularly with old metal showing signs of rust. With my GT6 I lay on the floor and attempted to use a mig welder but there was spatter everywhere and I have the scars to prove it. In the end I turned the body upside down and made the welds. If possible get your car raised on a garage lift and get someone who is good with gas welding to fit the new plate. Whatever happens do not give up. Tim Quote Link to post Share on other sites
shuggie159 Posted July 19, 2014 Report Share Posted July 19, 2014 Roger I've got one of those chassis rollers. The type where you bolt it on the wheel studs and tip the car on its side. Frost used to sell them. I must admit to having had some trepidation when I used it, but it worked fine. They were meant to do Jags and even VW caravanettes so its man enough. Its not ideal for your purposes, but if you can brace up the chassis with blocks and clamps, it would allow you to do all the welding at least kneeling down. It's yours if you want it. I'm not that far away - S Croydon. PS the best way to lift the car is to get half a dozen hefty blokes to tip it over. Otherwise where to lift etc is a bit tricky. Its currently on loan to a tech college so I need a day or two to retrieve it. The offers open to anybody else who wants to borrow it. Quote Link to post Share on other sites
Alec Pringle Posted July 19, 2014 Report Share Posted July 19, 2014 Hi Roger, in similar vein I have a roller made specifically to bolt onto TR7 bumper mounts (bumpers removed), which could easily enough be adapted to fit a real TR with a cunning bracket or four. It does allow the car to be easily rolled onto its side as it were, makes the unobstructed chassis a darn sight more accessible. Big hefty blighter to cart around, medium van or pickup or trailer, too big for an estate, but yours to borrow if you wish. Cheers Alec Quote Link to post Share on other sites
John Morrison Posted July 19, 2014 Report Share Posted July 19, 2014 Upside down Mig Welding is not so bad. When I was involved with doing extensive chassis repairs, I used some similar gauge bits of scrap, fixed to the chassis with mole grips This let me play about with welder settings and get a bit of practice of upside down practice before starting on the car found this invaluable, then with a decent face mask, very good exterior lighting, it can be gloomy under a car, and gauntlets over a boiler suit sleeves, it was all straight forward. John Quote Link to post Share on other sites
ctc77965o Posted July 19, 2014 Report Share Posted July 19, 2014 Remember there's a fuel line running nearby... in answer to your Qs: 1) no 2) yes, simply to maintain roadworthiness whilst other projects get completed 3) yes 4) No, its all bolted to the body A plan is forming. I'm going to get dirty. tired, burnt, possibly set the car on fire. What the heck. Quote Link to post Share on other sites
littlejim Posted July 20, 2014 Report Share Posted July 20, 2014 (edited) Can't see why you can't use clamps if welding a brace is a problem. But you have to weld the T-shirt in. Take up Alec's offer. Welding in a comfortable, weld lit pose, beats upside down can't see a thing welding. MIG - dunno if you can turn the arc down far enough. I used MIG. Edited July 20, 2014 by littlejim Quote Link to post Share on other sites
Tony Millward Posted July 20, 2014 Report Share Posted July 20, 2014 I'm very surprised that the 4A only has one 'T' shirt. Is it not possible to fit 2 as per the TR5 chassis and make it stronger? You'll get there Rodger, it will be great when it's finished.... Tony Quote Link to post Share on other sites
littlejim Posted July 20, 2014 Report Share Posted July 20, 2014 (edited) In my case, as you can see, the T-shirt wasn't the only bit rusted. Be brave and give the metal a decent belt with a hammer round the suss areas. 'Boing' means good, 'crunch' means replace. Edited July 20, 2014 by littlejim Quote Link to post Share on other sites
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