Rktr4a Posted February 2, 2021 Report Share Posted February 2, 2021 Hi all , My chassis lower t shirt - breastplate panel is out of shape and has some rust evident and I want to replace with new. Do I have to brace surrounding chassis members before I cut out? Or can I just cut out and replace.? Regards Rob Quote Link to post Share on other sites
trchris Posted February 2, 2021 Report Share Posted February 2, 2021 Hi Rob Im in the middle of this job myself I found some areas of chassis rot underneath so be warned you may find the old tin worm as well .I cut out and replaced using 2mm steel thankfully only the lower length section of the chassis but I did cut more than I needed too going towards the rear and replaced the strengthening plates you find inside making up the box sections while I was about it. Im replacing the breast plate using 3mm plate slightly larger than the original, especially along the trailing arm chassis members and about an inch longer on the main chassis leaving enough room to get to the prop bolts of course. Chris Quote Link to post Share on other sites
Rktr4a Posted February 2, 2021 Author Report Share Posted February 2, 2021 Hi Chris, Did you make a pattern panel for this yourself? Quote Link to post Share on other sites
trchris Posted February 2, 2021 Report Share Posted February 2, 2021 Hi Rob I did, the new panel I got was distorted( I think from when the pressings were made in it to give it rigidity) and made from 1.2mm steel so I sent it back and made my own as I say from 3mm plate using the old as a template so its identical but extending it about 2inches front and rear and along the trailing arm sections. Forgot to mention I didnt brace anything but made sure the chassis sat level and made a few measurements in a couple of places(before cutting old sections off) and just checked before final welds all done on stands high enough so I could weld comfortably which is a challenge in itself! Chris Quote Link to post Share on other sites
Rktr4a Posted February 2, 2021 Author Report Share Posted February 2, 2021 Hi Chris , sounds like a better alternative, I assume that you didn't need to put reinforcing pressings on your panel due to thicker steel? Quote Link to post Share on other sites
rvwp Posted February 3, 2021 Report Share Posted February 3, 2021 Hi Rob, My experience with my 4A chassis was once the old breast plate was removed the metal of the chassis was corroded. This is very typical of the 4A and 6 chassis breast plates. Although welding on a new breast plate would cover the rusted frame would be false economy and should not be done. The attached pictures show my chassis repair before welding on the new breast plate. Rich Quote Link to post Share on other sites
stuart Posted February 3, 2021 Report Share Posted February 3, 2021 This is what you usually find when you remove the T shirt, I always remove them even if they look good as you can guarantee the legs are rotten underneath it. Stuart. Quote Link to post Share on other sites
trchris Posted February 3, 2021 Report Share Posted February 3, 2021 Hi rich totally agree I was fortunate with mine not to be badly corroded I only had to repair the lower part of the box section on one side as I said I cut out more than needed my idea of replacing the breastplate with 3mm plate was to give a little bit more strength in this area. No way should anyone just replace the breastplate and think its job done Chris Quote Link to post Share on other sites
rvwp Posted February 3, 2021 Report Share Posted February 3, 2021 I guess that's a TR6 Stuart, double the trouble, I remember it well from my 6 restoration! Rich Quote Link to post Share on other sites
trchris Posted February 3, 2021 Report Share Posted February 3, 2021 Hi Rob No I didn't these are put into smaller gauge steel to add rigidity just make sure all the chassis that you expose is rot free and repair before replacing the breastplate I cut out and repaired both sides of the chassis ( I only needed to do one section) as although the metal looks ok its still 50 odd years old so would have lost some of its strength possibly OTT but peace of mind Chris Quote Link to post Share on other sites
Rktr4a Posted February 3, 2021 Author Report Share Posted February 3, 2021 That's great guys thanks for all the advice regards Rob Quote Link to post Share on other sites
Hamish Posted February 3, 2021 Report Share Posted February 3, 2021 May be a really dumb/ obvious but why is it called a t shirt panel ? Quote Link to post Share on other sites
stuart Posted February 3, 2021 Report Share Posted February 3, 2021 48 minutes ago, Hamish said: May be a really dumb/ obvious but why is it called a t shirt panel ? Because its the shape of a "T" shirt. Stuart. Quote Link to post Share on other sites
ianc Posted February 3, 2021 Report Share Posted February 3, 2021 Stuart's photo is frightening - I wonder how many TRs are like that. Ian Cornish Quote Link to post Share on other sites
Hamish Posted February 3, 2021 Report Share Posted February 3, 2021 42 minutes ago, stuart said: Because its the shape of a "T" shirt. Stuart. Ah I see it now Doh!! Quote Link to post Share on other sites
stuart Posted February 3, 2021 Report Share Posted February 3, 2021 17 minutes ago, ianc said: Stuart's photo is frightening - I wonder how many TRs are like that. Ian Cornish Its why I always remove the lower one during restos even if they look fine as that one did. Stuart. Quote Link to post Share on other sites
Malbaby Posted February 3, 2021 Report Share Posted February 3, 2021 This is one of many chassis strengthening modifications that I made. 3mm plate with additional 3mm strips. Quote Link to post Share on other sites
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