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I Just Want to Remove the Overdrive!


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I'm wanting to remove my J-type OD unit to have it repaired or exchanged as I've been unsuccessful in getting rid of the shock when it engages and disengages.  The gearbox and clutch were also overhauled by/for the PO ond both work fine so I'd rather leave them in place if I can as I have a back injury.

I've removed the propshaft flange and was hoping I can lift the grearbox with a trolley jack and swing the OD up to clear the tunnel by pivoting on the engine mounts.  I will have to at least remove the exhaust system to do this.

Will this work?  Do I need to remove the gear selector/gearbox cover assembly? Can I dismantle the OD unit and remove it piece by piece starting at the back end (bearing in mind my earlier comments)?  I realise that the rebuilt/exchange unit will have to go back in one piece but that will be less of a mental challenge once I have got to that point.

Any other thoughts or comments would be much appreciated

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ooh thats a challenge,

It was once done on an A Typr Overdrive, I remember, some time ago now reading the article in TR Action, but its not easy, and of course it also has to be replaced again, not easy.

My advice  would be not to try, but to remove box and overdrive together, split on the bench, and reassmble the same way.

I would be concerned about having a bad back, and going near this job. If you must attempt. then might I suggest a gearbox crane to take all the effort out of the heavy stuff, works exceptionally well, both fitting and replacing, I can let you have details .

John.

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You have to have an exceptional reason to try and remove the overdrive only, it is of a weight itself and when the overdrive and gearbox are mated back together you have to juggle the overdrive fitting onto the gearbox needing three hands and gaining a new exposure to swear words...it's hard enough to do with the gearbox positioned vertically with gravity helping the overdrive sliding it on whilst you fiddle and arrange the bits.

Having a bad back is indeed a reason not to get involved with lifting in confined areas and I would consider paying a neighbour, local friend or nearest TR enthusiast or other classic car freak to help with the gearbox and overdrive removal combined whilst you encourage and explain the method and then refit the unit for you after the overdrives return to health.

Mick Richards

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+1

Having just completed another overdrive & box rebuild 'on the bench' I can't even start to imagine how you'd be able to undertake an O/D removal & replacement in situ..I'm fairly sure that even my extensive vocabulary would run out of expletives in fairly short order....:D

Having said that I am only familiar with the A type & the J type may be less challenging - I have no experience of them.

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Not quite a J type or a TR for that matter but have a look at JY Classics facebook page for 9th May but they have done the OD in a Mk2 Vitesse without Gbox removal, but personally I would go for removing the whole G/Box Overdrive. My back is past its best but I find its not just heavy lifting but also awkward twistingg ! and I would guess there would be a lot of this involved if you were to attempt splitting the box from the OD in situ.

Edited by Graham
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+1absolutely! You might get it apart with many important internals falling on the floor, but rebuilding and getting it back would be impossible. Apart from removal/install (use some sort of crane, as well advised above),  I found this to be the only way to assemble, if health is a challenge.

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Alf

 

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11 hours ago, stallie said:

As an aside? What have you investigated to get rid of the shock with engagement and disengagement?

This link to my earlier thread gives the background

https://www.tr-register.co.uk/forums/index.php?/topic/71067-j-type-overdrive-harsh-shifting/

I think NobbyC's suggestion of the bronze thrust washer having been left out is quite plausible, hence the decision to remove the unit.

Edited by KiwiTR6
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5 minutes ago, dingle said:

Actually, I have read of the J type being removed&replaced without removing the trans. Simpler than trying the same stunt with the A Type. Might be worth a try. The clutch springs are contained in the OD/adapter housing, so shouldn't be a problem.

Berry

Thanks Berry.

Any idea where you might have read it?

 

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Hi Gavin,

It is better to sent GB with OD to your specialist. When complete, it can be bench tested as an assembly, if he has a drive.

Good luck,

Waldi

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Thanks for the advice 2 x John's, Mick and Alf.  Thankfully I'm not a complete cripple, I just have to be careful when lifting.  I'm fortunate enough to have a 2-post hoist, engine crane and willing helpers I can call on if necessary.  If in the end the gearbox has to come out, it will!

The guy doing the rebuild tells me the OD unit is relatively light and that's the only thing that needs attention, hence my question.

Cheers

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3 minutes ago, Waldi said:

Hi Gavin,

It is better to sent GB with OD to your specialist. When complete, it can be bench tested as an assembly, if he has a drive.

Good luck,

Waldi

Hi Waldi.

My specialist has plenty of gearboxes and OD units on hand so testing shouldn't be an issue.  It's essential that it is working correctly after going to all of this trouble, hence why I'm not attempting it myself.  Although in different circumstances, I may well have given it a go!

Regards

Gavin

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Hi Gavin,

what I meant is that testing OD + GB as an assembly will ensue there is no defect related to the connection, like a main shaft with axial play.

Waldi

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Well, it seems it's not possible to remove the OD unit on its own!  Not easily anyway.  It may be possible if the radiator is removed and the engine mounts freed so that the engine could be moved forward or rearward as appropriate, but removing the gearbox and OD together would be a much easier approach as it turns out.

Despite my best efforts, I found that the gearbox can neither be lifted high enough pivoting on the engine mounts to clear the rear tunnel nor dropped low enough to to remove the OD through the floor.  

In the first instance the gearbox's vertical movement is limited by the firewall and the OD will not clear the tunnel with the gearbox still attached to the motor.

My next move was to drop it out through the floor (certainly looked feasible from above and underneath). To make the job easier I removed the front section of the prop shaft, the the rear gearbox support bracket and the gearbox cover/shifter assembly.  As an aside, the bolts securing the support bracket have tabs brazed to them making removal extremely easy.  A very simple and clever idea!

All was looking good with the engine dropped as far as I could with the rear of the cylinder head pushing hard against the battery tray and the lower fan blade hard against the radiator core.  I disconnected the OD unit from the gearbox and slid it back on the shaft only to find that it was prevented from sliding completely off by the rear support brackets on the inside of the chassis rails.  There was no way it would fit through.it was just too wide for the gap between the brackets.  Damn!!!

The only upside to this was that I was able to easily remove the upper bellhousing bolts.  The real downside was that I couldn't get the OD unit back into its original postion to secure it to the gearbox.  It was hung up on something and I wasn't prepared to force it so gearbox removal was going to have to be from that point forward in order to avoid any chance of bending the main shaft.  There was a lot of cold sweating going on at this point!

I then made up a support from a piece of angle iron and bolted it to the top of the box and blocked it from the floor.  I then fitted a ratchet tie-down secured to a bolt through the handbrake pivot to pull the gearbox back.  This work really well.  I used a large trolley jack to support the rear of the engine and a small one under the gearbox.  After some toing and froing with the jacks I had the box free and in a position it could be removed.  A quick call to my BIL sorted that.

From what I could see of the OD, the piston looked to be in a fairly sad state.  However its all packaged up now and I'll leave it to my specialist to diagnose the cause of the problem I've been experiencing.

Thanks everyone for your comments and advice.  Always much appreciated.

Regards

Gavin

 

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Thanks to everyone who offered their comments and advice.  All very much appreciated as always.

Gavin

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Edited by KiwiTR6
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Hi John.  The back is fine thanks.  The box assembly wasn't quite as heavy as I'd feared and my brother-in-law is a fairly burley bloke so not a lot of effort required on my part.

The OD will be at the specialist tomorrow.  When I spoke with him today I asked if he was going to run it up on a test rig.  His response was "No, I've been doing this for 40 years so it will be fine!" His name is Ian Preistley and originally from the UK so someone on the forum may know him from years past?

Gavin

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