rvwp Posted June 15, 2021 Report Share Posted June 15, 2021 Hi Guys, I am rebuilding a ex TR6 'J' type overdrive gearbox to eventually fit into my TR4A. I have a lower 'J' chassis bracket in my box of TR bits, but lack the gearbox mounted bracket Pt No 160118. This is on backorder at Moss. It's a very easy bracket to make, so I was wondering if anybody has such a bracket in hand and could provide basic dimensions. I could probably work the dimensions out by trial and error, but easier if they could be provided. many thanks Rich Quote Link to post Share on other sites
BlueTR3A-5EKT Posted June 15, 2021 Report Share Posted June 15, 2021 (edited) Do not forget the brackets in the chassis are in a different position between those for A type and J type (Lowere and further rearward for J types this drawing by Peter Taylor shews the two arrangements quite well see items 33. https://www.moss-europe.co.uk/shop-by-model/triumph/tr5-6/body-chassis/chassis-subframes/chassis-frame-tr5-6-1967-76.html Peter W Edited June 15, 2021 by BlueTR3A-5EKT Quote Link to post Share on other sites
peter clarke Posted June 16, 2021 Report Share Posted June 16, 2021 I bought a j type conversion bracket for my 3a and it failed. The cut out for the solenoid weakens the bracket and it suffered a fatigue crack and failed allowing the uv joint to drop onto the chassis plate. If you go this route suggest you add gussets to strengthen. Quote Link to post Share on other sites
rvwp Posted June 16, 2021 Author Report Share Posted June 16, 2021 Ah yes of course! There are brackets on e-bay sold as being suitable to fit a 'J' overdrive to a pre 73 TR6 chassis, using the original 'A' chassis overdrive mounting bracket chassis position, which look substantial. This bracket requires a Triumph later GT6/Herald GB mounting bracket 159656 to attach to the 'J' OD. Looking at these item, it would appear to be a good solution. Any observations ? Thanks Rich Quote Link to post Share on other sites
qkingston Posted June 16, 2021 Report Share Posted June 16, 2021 Hi Rich, I fitted the same bracket as shown in Peter's photo above, this has a cut-out to accommodate the solenoid which has the potential to weaken the bracket as described; this can be further exacerbated by owners needing to further open that cut-out to clear the solenoid. I had a non-overdrive gearbox on my 4a originally, so I believe that chassis bracket is different again. The alternative bracket you mention with the GT6 mount would be a better solution but the height is wrong using the existing chassis bracket (on a non-o/d 4a as described)...so it depends what chassis bracket you have to start with Best Regards David Quote Link to post Share on other sites
rvwp Posted June 16, 2021 Author Report Share Posted June 16, 2021 Hi, still a bit confused Peter - the Peter Taylor drawing you refer to, is that just the Moss catalogue diagram or something different? David - if I remember the TR4A chassis has the same gearbox cross member on the chassis as a TR5/6 up to 73, after which a 'J' type overdrive was fitted needing a different Cross member Moss Pt No 218275. A TR4A fitted with overdrive from factory would have been a 'A' type the same as the TR5/6 up to 73, using Cross member Moss part No 211361? I have both Cross Members. Comments welcomed please, Rich Quote Link to post Share on other sites
BlueTR3A-5EKT Posted June 16, 2021 Report Share Posted June 16, 2021 1 hour ago, rvwp said: Hi, still a bit confused Peter - the Peter Taylor drawing you refer to, is that just the Moss catalogue diagram or something different? David - if I remember the TR4A chassis has the same gearbox cross member on the chassis as a TR5/6 up to 73, after which a 'J' type overdrive was fitted needing a different Cross member Moss Pt No 218275. A TR4A fitted with overdrive from factory would have been a 'A' type the same as the TR5/6 up to 73, using Cross member Moss part No 211361? I have both Cross Members. Comments welcomed please, Rich I am giving due acknowledgement to the artist who created the illustration for the current users. Moss are the users of that catalogue drawing on their web pages and printed catalogues. Cheers Peter W Quote Link to post Share on other sites
qkingston Posted June 17, 2021 Report Share Posted June 17, 2021 22 hours ago, rvwp said: Hi, still a bit confused Peter - the Peter Taylor drawing you refer to, is that just the Moss catalogue diagram or something different? David - if I remember the TR4A chassis has the same gearbox cross member on the chassis as a TR5/6 up to 73, after which a 'J' type overdrive was fitted needing a different Cross member Moss Pt No 218275. A TR4A fitted with overdrive from factory would have been a 'A' type the same as the TR5/6 up to 73, using Cross member Moss part No 211361? I have both Cross Members. Comments welcomed please, Rich Hi Rich, my challenge is that I started with a non-overdrive box as a fair number of US 4a exports seem to have. The GT6 mount bracket doesn't work on that configuration unless the chassis gearbox cross member is modified (ie the height is dropped) David Quote Link to post Share on other sites
rvwp Posted June 17, 2021 Author Report Share Posted June 17, 2021 Hi David, Yes my TR4a although a UK car has a non overdrive gearbox currently. I see the alternative cross member offered on e-bay is stepped to lower it to use the GT6 mount. It does seem substantial? The Moss conversion kit is also stepped to lower it but uses a single cotton reel type isolation mount. Which way to go. Maybe I'm getting ahead of myself and I should wait until the Overdrive gearbox is in the car and mounted to the engine to properly see the height issues with the rear gearbox mount? Cheers Rich Quote Link to post Share on other sites
organman Posted June 17, 2021 Report Share Posted June 17, 2021 Hi Rich , I have sent you a personal message re these brackets. Chris Quote Link to post Share on other sites
stuart Posted June 17, 2021 Report Share Posted June 17, 2021 (edited) 59 minutes ago, rvwp said: Hi David, Yes my TR4a although a UK car has a non overdrive gearbox currently. I see the alternative cross member offered on e-bay is stepped to lower it to use the GT6 mount. It does seem substantial? The Moss conversion kit is also stepped to lower it but uses a single cotton reel type isolation mount. Which way to go. Maybe I'm getting ahead of myself and I should wait until the Overdrive gearbox is in the car and mounted to the engine to properly see the height issues with the rear gearbox mount? Cheers Rich This is how I did the last conversion. A type chassis to J type. Stuart. Edited June 17, 2021 by stuart Quote Link to post Share on other sites
ntc Posted June 17, 2021 Report Share Posted June 17, 2021 46 minutes ago, stuart said: This is how I did the last conversion. A type chassis to J type. Stuart. But why would anybody do that? Quote Link to post Share on other sites
stuart Posted June 17, 2021 Report Share Posted June 17, 2021 4 minutes ago, ntc said: But why would anybody do that? Because at the time I could only get an "A type" chassis to replace a completely rotten "J type" chassis under a CR car. Stuart. Quote Link to post Share on other sites
rvwp Posted June 18, 2021 Author Report Share Posted June 18, 2021 Hi Stuart, Thanks makes sense to convert an pre 73 chassis for a post 73 car with an originally fitted 'J' type OD, keeping the car as original. Not sure I would want to modify my original 65 TR4A IRS chassis to make it non standard, better to have a bolt on bracket to fit the 'non standard' 'J' type OD. You never know I may want to fit an original 'A' type on day? Thanks Rich Quote Link to post Share on other sites
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