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TR4 gearbox top cover / selectors - advice


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I need some advice

 

I have to change the gearbox top cover on my newly fitted overdrive gearbox. Seems the original selector top cover from my gearbox had the switch location in the wrong spot (on the RH side opposite the reverse lights switch) meaning I had the luxury of overdrive on all 5 gears (reverse too if I had been silly enough to try it)

 

So never having pulled one of these off before is there any special tricks to removing the selector & forks & fitting the new one? Its being done in the car just to make it interesting!

 

all help appreciated

 

Graeme

Edited by Graze
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Hi Tony,

have a look here http://www.buckeyetriumphs.org/technical/Gearbox/GearboxCover/GearboxCover.htm

 

Taking the cover off thew car is easy.

The three selector forks are held in with a taper lock screw and quite often they break when undoing. A 4 or 8 sides socket should be used.

If you need to remove the rods, then you will need to remove the dent balls that the rods lock against.

On a 4/4A they have caps that are usually screwed in. On the 6 they are like little core plugs.

Once removed the rods can be withdrawn.

Remove the outer rods first and the centre rod last. Remember catch the balls etc that create the interlock.

 

The incorrect switch hole can be blanked off. A new switch holed put in the correct place - 3/4 the gear on the left looking from above.

The thread size for the switch is unknown but people are using 16mm x 2mm it sort of works.

The correct size is 5/8 dia x 13TPI - it does exist as a common thread.

 

Roger

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The little square head taper lock screws can be loosened by using a brake adjustment spanner which generally has two sizes of square "holes" one of which I found exactly fits the taper lock screw square heads

Just though to share that with you and others as it helped me when I was replacing the rubber grommets on the selector rods (trying to stop leaks eventually solved by adding a big vent to to the top)

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Hi Michael/Graeme,

regarding the rubber seals on the selector rods.

Mine were leaking quite badly. Somebody on here suggest using Q-seals (Quad seals)

These are like O-rings but have a cross section like a four leaf clover.

The depth of the counter bore where the seal are positioned is much deeper than the gauge of the O ring and so can float about.

In theory this shouldn;t matter but it does.

Use some sprt of packer to keep the rings in place.

 

The o-rings have a number like 112. The Q-seal is something like 4112 or Q112

Various suppliers around the world. in the UK I used MayDay seals.

 

Roger

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Thanks Michael/Roger

 

Seems my 3rd/4th selector fork on the replacement is badly worn so I will need to pull the current one off the car and hopefully it will be in better shape and can be re-used

 

Graeme

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Roger

 

thanks for the advice & link to buckeye

 

removed, stripped, switch threads tapped into the cover - will have O'drive on 2nd, 3rd, 4th

 

cover painted & ready to re-install

 

It was a relatively easy job & I had lots of help from someone who knew what they were doing

 

next challenge will be the wiring to the switches

 

I know that i need to wire the two switches to each other & to ground off one side, then the column switch has two wires - yellow/ green to switches & then to solenoid?, where do I wre the other one to get the power?

 

where do i take the power from & connect it to - do i need a relay

 

J type overdrive

 

advice appreciated

 

Graze

 

 

post-12376-0-69677100-1493109874_thumb.jpg

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Roger

 

thanks for the advice & link to buckeye

 

removed, stripped, switch threads tapped into the cover - will have O'drive on 2nd, 3rd, 4th

 

cover painted & ready to re-install

 

It was a relatively easy job & I had lots of help from someone who knew what they were doing

 

next challenge will be the wiring to the switches

 

I know that i need to wire the two switches to each other & to ground off one side, then the column switch has two wires - yellow/ green to switches & then to solenoid?, where do I wre the other one to get the power?

 

where do i take the power from & connect it to - do i need a relay

 

J type overdrive

 

advice appreciated

 

Graze

 

 

Why is the rear housing fitted upside down?

Stuart.

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Why is the rear housing fitted upside down?

Stuart.

 

So obvious, really. But it was Stuart that spotted it.

 

Amazing it's possible - better to remember Sod's law.

 

AlanR

Edited by TR 2100
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Why is the rear housing fitted upside down?

Stuart.

Well that is a good question?

 

shortage of TR experts still alive here

 

thats the way I got it back from the guy who refurbed it & i didnt know any better

 

seems to work ok - is there any long term consequence requiring me to pull it all apart & re install (or do I just leave it till next time I need to pull it out?)

 

Graeme

post-12376-0-99011300-1493199796_thumb.jpg

Edited by Graze
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The machined surface, facing upwards, is supposed to

sit on top of a rubber mounting.

Rubber mounting has two bolts through the gearbox

There is a plate that sits on the chassis.

 

So - how is your gearbox fixed to the chassis?

 

AlanR

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Interestingly Alan its a J type and has a bracket botled to the chassis which sits across under the back of the o'drive with a rubber mount and an L shaped bracket which is bolted to the back of the overdrive cover - all as its meant to be I'm sure

 

Also my cover has two bolt holes on the underside too -- but not used due to the bracket

 

Graze

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This exploded diagram shows the rear of the casing and it certainly looks from your picture that yours is fitted upside down so Im wondering where the rear mounting bracket is bolted to, can you get us a picture please?

http://www.moss-europe.co.uk/shop-by-model/triumph/tr5-6/clutch-transmission-drivetrain/overdrives-components/163e52.html

Stuart.

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That's Weird as the Angle Drive is in the right position.

Im wondering if its a Volvo rear casing perhaps?

Stuart.

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You could have warned us to put sun glasses on before opening that photo Stuart :o

 

Bob.

Ha ha sorry it is a bit bright!

Stuart.

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Stuart photo now attached to previous post

 

cooking dinner got in the way

 

entirely possible its a volvo unit - purchased from the US

 

 

Graeme

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Interesting bracket, Moss seem to sell them to convert "J" type boxes to "A" type chassis mounts but it still doesnt explain why the housing seems to have the mount on the top but the speedo drive out the correct way.

Stuart.

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