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randall977

Removing the o/d unit without removing the gearbox?

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Is it possible to remove the o/d unit without removing the gearbox in a TR4? Sadly my o/d doesn't seem to work - solenoid is fine...

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In a word no. The overdrive needs separatings about 4 ins or so before its clear of the gearbox main shaft, and even if there was room, trying to line up the splines and fit the springs with th box horizontal never mine still in the confines of the car would be more than impossible It took me best part of a day to replace the overdrive onto my box the other week and I thought I was being careful lining it all up !! Before resigning to the fact of removal try a few other checks first

Does the solenoid pull the operating lever fully There iss a lever on the oposite side of the box with the tunnel cover off ( its got to come off anyhow if the box is for out) you can pull it to engage overdrive manually ( with the car moving of course!) Dont try it in reverse!! If this fails see if the pump plunger is stuck. Remove the brass castleated plug underneath, along with all the oil remove the filter and the lower housing ( 2 screws i think) By rotating the propshaft you can see if the plunger goes up and down if its stuck some times a carefull tap can free it. After that theres not much else thats better done with a the assy in the car so its out she comes Its a good oportunity to see the state of the clutch operating fork and pin. Mine was broke and there was about 1/2 in play at the thrust bearing end

Cheers Dale

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Thanks Dale. I didn't do the pump test but I did the rest. I've taken the gearbox out four times in the last eight months so why not a sixth! Tonight I will have a look inside...

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Actually it's a qualified no, if you are planning to take the O/D apart then you can remove it section by section from the the main shaft(need to raise the rear of the box as much as possible and remove the handbrake lever)........... it's a bit of a fiddle,but reassembly is possible this way too...... ask me how I know?.... been there done that!!

Cheers Rob

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It is essential to effect a good seal at the joint between gearbox and overdrive, and I would have thought that the chance of getting this right would be considerably reduced if the job were undertaken other than with the whole gearbox plus overdrive unit out of the car.

Ian Cornish

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Thank you for your replies and advice. I think it might be possible to remove it in situ but having taken the gearbox out four times previously I'm now pretty quick at it...and my back has survived so far! I removed the gearbox and have stripped the o/d, looks like the pump wheel and associated cam have worn badly so I'm guessing a loss of pressure has knocked out the o/d. It is much easier to take the o/d apart and put it back together with the gearbox out so I think I've done the right thing, it's just very disheartening after all my previous clutch problems...which I never found a cause of.

 

Christian

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It is essential to effect a good seal at the joint between gearbox and overdrive, and I would have thought that the chance of getting this right would be considerably reduced if the job were undertaken other than with the whole gearbox plus overdrive unit out of the car.

Ian Cornish

 

Agreed Ian,....so.... sandwich plate off for a good clean up,new gaskets either side (this is one for Alex) thin smear of Hermatite Red on both faces plus the cleaned up faces of the O/D body to rear cover joint..... all done up tight .... no leaks.

Once apart overdrives are remarkably simple things, just a case of making sure everything is completely clean and reassembled according to the workshop manual.

Cheers Rob

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It only took me about 3 hours to put my overdrive back onto the gearbox and that was with the latter vertical on the bench.

 

After I had done it a friend told me that I should have made a small bevel on the leading edge of the mainshaft splines with a dremel to make the alignment easier. Apparently it only needs to be about 0.5mm which has no effect on the effectiveness of the. Wish I had known that before I started.

 

Plus, ORS told me to use Wellseal for the joint rather than Red Hermatite.

 

Rgds Ian

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Advice from ORS is correct - Wellseal is superior for this sort of duty (and for head gaskets on 4-pot engines).

Ian Cornish

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Trick is to make sure the splines and grooves are aligned by first assembling without the springs.

 

My experience.... if you want the joint to leak use Wellseal, if you don't want it to leak use hermatite Red.

Cheers Rob

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I do remove the J-OD from my gearbox with it still mounted in the car.

I'm not sure if this can be done with an A-OD as the A is much larger and heavier. Splines and pump is also different than with a J-OD.

 

Give it a try if you like but don't be too disappointed if the A won't come out.

 

Cheers

Chris

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I've spent a very frustrating evening trying to get the very end of the main shaft to sit in the bush. It is very slightly bevelled already, should I bevel it further?

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I think Rob meant bevel the splines,as a last resort, not the end of the shaft. I assume it's on the bench? if so, with the tail section vertical (held in the gap in a 'Workmate' table?) and a good light you have to align the clutch and splines before inserting the box vertically from above. Ideally with a 'spare' shaft if you have the box already assembled.

 

john

Edited by johnny250

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The splines are no problem, with two of us it's quite easy to twist and align while dropping the o/d section on. In theory the end should drop in...but it doesn't!

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It's not your new pump roller/cam alignment stopping it is it? shaft turned to lowest point on the cam?

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Well it finally went in and all turns nice and freely - thank you for your advice. If the o/d does not work now I will be very unhappy indeed!

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It still does not work, pressure test guage ordered!

 

 

OH No! you should have done that bench test :mellow: Even rotating the output shaft by hand a few 'dozen?' times should build enough pressure to operate the O/D..... Have you checked the operating valve spindle for blockage? is the oil rising to the top if you leave the valve plug open? Did you have the accumulator piston out to check all OK whilst you were in there?

 

john

Edited by johnny250

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I didn't realise that you could test it by manually rotating. We didn't take out the accumilator piston as it required a threaded tool and the bore was perfect, it didn't want to come out easily so we left it. My thoughts are; poor seat or ball bearing in one of the valves or ...the accumilator piston. I think I can access all of these without removing the g/b...

 

The pump was so badly worn that we thought we had found the problem - everything else looked very good...almost like it had nto been used!

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Think you'd go some to generate 400 psi or so by turning the gearbox input by hand, most seem to use a heavy duty hand drill (two hand variety) Have you checked the operating lever is set corectly? Slacken the clamp on the solenoid lever and operate the overdrive off the lever on the otherside. My overdrive seems to now work slightly more slugishly after changing from straight 30 engine oil to penrite 40 gear oil, but the gearbox is quieter after replacing all the bearings. Maybe the oil helps aswell.

Dale

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If all working OK, with the pressure gauge fitted to the operating valve...make an adaptor or drill a spare plug to retain the internal spring/ball/shaft, you can rotate the output shaft (anticlockwise) by hand and watch the pressure rise at every pump stroke. You can then 'fire' the solenoid lever to see the pressure fall... using a motor drive allows complete cycling and gearbox testing too.

 

john

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Just a quickie

 

 

Fit the gearbox to the overdrive!!!

 

Hold the o/d in the vise by one of its mounting ears.

 

Lower the gearbox onto it without springs or pump cam fitted - get the splines aligned by turning the gearbox NOT the o/d - then do not rotate anything!!!

 

Lift off the gearbox, fit springs and cam (held in place with a gob of grease) with the cam set at its lowest point in line with the pump. - some pump cams have a ramp to help the engagement.

 

Depress and Wire down the pump plunger. - you can fish through the side with a long screw-driver at the last minute if you feel confident.

 

Fit all 8 springs in correct places. - unless you have a 2000 Innsbruck A type o/d in unmodified form.

 

Fit gasket and apply suitable goo.

 

Lower the gearbox onto the o/d as before

 

Push by hand the gearbox onto the o/d (as you tighten the 2 nuts on the 2 long studs) to ensure nothing is binding (I find a bit of a bounce is in order to give re-assurance that all is not jamming)

 

REMEMBER do not turn the O/D flange, only the gearbox input shaft. - If it all goes tight as you are assembling STOP or you will need to buy a new adaptor plate after you have bent/cracked it due to misalignment.

 

Remove wire at last minute, and tighten all home. and Hey presto it's all done.

 

 

Cheers

 

Peter W

 

PS Read the book on how to do it

 

PPS I have never attempted to remove the A type o/d with the gearbox assy in the chassis as it looks as tho there is insufficient room or the correct directional pull of gravity.

 

PPPS If you have the tunnel out you are 3/5 of the way there. JFDI

Edited by BlueTR3A-5EKT

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