View Full Version : Overdrive Removal

Bob Hughes
09-02-2003, 04:07 AM
Having been off the road more than on this year, with front suspension problems and a failed overdrive solanoid, I am now faced with the prospect of a failed uni directional clutch in the overdrive unit. Travelling in fourth at circa 4000 revs just about to slip into overdrive and away rose the revs with no gain in speed, slipped into overdrive, all ok again. Question, has any one experience of removing the overdrive without the gearbox, how do you do it and how easy/difficult is it? graemlins/violin.gif graemlins/england.gif

09-02-2003, 10:21 AM
Hello Bob,

On my Triumph 2000, I need to drop the end of the gearbox to allow it to clear the gearbox tunnel. I suggest you have a look, it should be fairly obvious, bearing in mind it has to go backwards a fair way to clear the gearbox output shaft. You may also have to disconnect your exhaust.
It can be quite tricky to replace however, as the output shaft splines engage in two adjacent components of the O\D and they must be lined up spot on or it will not go back on. Do not force it or you will crack the backplate. There is a special dummy shaft tool which is the recommended way, but you can use a long screwdriver or similar to line them up but be patient. I found a heavy soft hammer useful to bump the O|D on helpful, but as I said take care.

Alec graemlins/cheers.gif

w. scott brunkhurst
09-02-2003, 04:58 PM
I believe you can pull the OD unit while in the car, but you'll probably never get it back together.


09-02-2003, 05:12 PM
Hello SB,
you are a bit pessimistic, O\D's are quite easy to work on using a manual, and spares are available from specialist, at least here in the UK. Just take care in replacing them onto the gearbox.

Alec graemlins/cheers.gif

09-09-2003, 08:36 PM
I rebuilt my tranny along the way to restoring my car. I can't imagine being able to get the OD back on while the tranny is in the car. Just getting the oil pump onto the cam was a tricky process. I had to set the tranny on end so all the gears and parts would stay lined up. The casing bolts had to be walked tight by alternating side to side to avoid binding at the rear bushing. I practiced some good language skills to help the process. Good luck with your project!

Randy Forbes
09-12-2003, 12:54 AM
<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by w. scott brunkhurst:
I believe you can pull the OD unit while in the car, but you'll probably never get it back together.


Actually, I think the trans tunnel will leave you just shy of getting the unit off, but you are absolutely correct about never getting it back on!

Overdrives are not hard to overhaul and are pretty straight forward. I do suggest that the first time you tear one down that you do it on a long workbench and lay the components out in order as you remove them. Once you have a thorough understanding of the unit, you won't have too much trouble putting it back together.

Back in the Seventies when I worked at Austin-Healey West (in San Francisco), I used to rebuild the overdrives only (they did their own transmissions) for XKs Unlimited. Their shop used to be in Walnut Creek (I believe they're in San Luis Obispo now?).

[ 09-11-2003: Message edited by: Randy Forbes ]</p>

Dave Russell
09-12-2003, 01:43 AM
<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by Randy Forbes:

Actually, I think the trans tunnel will leave you just shy of getting the unit off, but you are absolutely correct about never getting it back on!

So I have heard many times.

09-12-2003, 03:25 AM
Wow...it's been more than 35 years ago that I rebuilt my Overdrive unit...it did come out and go back in...of course we broke the front plate...and a screw on it...did a micky-mouse soldering job to get it back together...and it held up for many, many years...good luck...you just brought back waves of memories for me...almost like it was yesterday...almost... coolgleam.gif

09-12-2003, 03:37 AM
Hello Bob,
I am just interested if you have had a go at repairing the overdrive?
There seems to be a few who say it will not go back on, but once you strip it down you will see where the problem of refitting it lies and if both those internally splined components are in line it will go back on. (Unless you have a dummy shaft, it can take a few goes to get them lined up spot on.) Understanding the problem is 80% of getting it back on the gearbox.

Alec graemlins/cheers.gif

Bob Hughes
09-12-2003, 04:10 AM
Thanks for all the advice chaps, but I may have some good news, having read several articles on changing in and out of overdrive, I have taken to use the clutch. It is just possible that I dipped the clutch, leaving my foot on the loud pedal, just before I changed into overdrive, causing the revs to rise, only time will tell. I've thrown caution to the wind and given the car a good thrashing to try to create the problem again and failed. I have contacted an Engineer in Sheffield (Overdrive Repair Services) and he rebuilds overdrives for around 280 + vat depending on the degree of damage, the more damage the greater the cost. So I have a source should trouble occur. Thanks again

graemlins/cheers.gif graemlins/england.gif