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IRS chassis 'J' type Overdrive gearbox mounting bracket


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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

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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 by BlueTR3A-5EKT
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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.

Inkedj type mount_.jpg

temp repair.jpg

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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

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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

 

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Hi, still a bit confused :huh:

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

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1 hour ago, rvwp said:

Hi, still a bit confused :huh:

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

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22 hours ago, rvwp said:

Hi, still a bit confused :huh:

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

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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:unsure:.  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

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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:unsure:.  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.

 

CR 526 O 030.jpg

CR 526 O 031.jpg

CR 526 O 032.jpg

Edited by stuart
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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.

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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

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