Fitting an overdrive gearbox
Posted By : Philip Rosenberg, 07-Jan-2005, 03:18pm
I can let you know what my experiences were if it's any use.
I got a secondhand one, with propshaft, mounting bracket and speedo drive (I think that's all the bits you need) for &163;250. I stuck it in and the condition turned out to be mediocre. Third gear crunched and there was an oil leak. I lived with it for about a year but now as part of the general overhaul I'm doing on the car I decided to get it sorted. A gearbox overhaul kit from canley's was about &163;60-&194;&163;70. So far I've dismatled it all and sure enough the synchro on third was well worn. Now I just have to reassemble it!!
The oil leak seems to be coming from near the solenoid, but the guy at canley's gave me some suggestions and although I haven't looked at it properly it hopefully won't involve dismantling the overdrive and shouldn't be too pricy.
As it happens the solenoid seems fine and there's no sign of clutch slipping. If there had then it might have been a good deal pricyer as I wouldn't have attempted to dismantle the OD. The gearbox has been my first real technical bit of work on the car. Like I say I haven't reassembled it yet but it hasn't gone too bad. I'm told OD units are a bit scarier though.
In my case it seems to have gone okay and I should have a good OD box for under &163;350, but if the OD itself had been nackered it might have been a different story.
Hope this is of some help
Phil
I got a secondhand one, with propshaft, mounting bracket and speedo drive (I think that's all the bits you need) for &163;250. I stuck it in and the condition turned out to be mediocre. Third gear crunched and there was an oil leak. I lived with it for about a year but now as part of the general overhaul I'm doing on the car I decided to get it sorted. A gearbox overhaul kit from canley's was about &163;60-&194;&163;70. So far I've dismatled it all and sure enough the synchro on third was well worn. Now I just have to reassemble it!!
The oil leak seems to be coming from near the solenoid, but the guy at canley's gave me some suggestions and although I haven't looked at it properly it hopefully won't involve dismantling the overdrive and shouldn't be too pricy.
As it happens the solenoid seems fine and there's no sign of clutch slipping. If there had then it might have been a good deal pricyer as I wouldn't have attempted to dismantle the OD. The gearbox has been my first real technical bit of work on the car. Like I say I haven't reassembled it yet but it hasn't gone too bad. I'm told OD units are a bit scarier though.
In my case it seems to have gone okay and I should have a good OD box for under &163;350, but if the OD itself had been nackered it might have been a different story.
Hope this is of some help
Phil
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Fitting an overdrive gearbox
Posted By : Don Cook, 07-Jan-2005, 06:21pm
I bought a gearbox with OD for my GT6 for &163;75 - how clever I thought! Well, the OD never did work and the gearbox soon displayed all the traits of being shagged out. My original box is back in and I don't miss OD at all...never having had it.
I too have bought a gearbox overhaul kit and will repair the box at some point but it doesn't mean the OD will work!
If you have the cash then use Canley's.-
Fitting an overdrive gearbox
Posted By : Jason Chinn, 08-Jan-2005, 10:36am
Second hand gearboxes are a lottery - you can't really tell that much about it with the box out of the car and unless you can have at it with the spanners you're really just flipping a coin. Yes you can tell if it's totally shagged when the mainshaft is flopping about but even then I've seen those salvaged with little more than a bearing and some gaskets to make it useable (not great but hey, when you're skint useable is good).
Buying second hand and then getting someone to "check it over" seems like a good idea and it can save you money BUT if they are really checking it then they have to go about half way to reconditioning it and it's a small step to a proper job (with associated costs).
My experience is that even when the professionals get their hands in your gearbox mistakes can be made - even the best guys can get it wrong because they are working with limited resources - for instance there are cheap eastern european synchro rings out there - they just don't work. There are crappy gaskets that are so thin you need to use two to get a good seal. There are "reclaimed" mainshafts that are useless and fail after a few thousand miles. There are no new gears so you're reliant upon selecting the best from a dwindling stock of used ones. Oil leaks and selection problems can be cured but because of the lack of gears, noise is hard to fix.
I recently acquired a J type overdrive, it was free with a load of other "rubbish" that an ex-Triumph owner was pleased to get rid of. I just piled it in the car and went home to sort through what was worth keeping and what was worth selling on. It turned out to be a brand new, never run late Dolly unit - ideal! However, when trying to use it, it turned out to be solid with 20+ years of congealed grease and associated spider webs! I took it to my specialist who spent the time needed on the test rig to set it up right - it may as well have been a second hand unit.
After all that doom and gloom I guess what I'm saying is that you do need to be realistic with the "risks" you take with a second hand box and/or overdrive. Do it yourself but be prepared for some mistakes and at least one failed installation
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