J Type Overdrive not engaging when Hot

[tiggrr1]

I thought I'd start another post on my J type overdrive as this is a separate issue to the addition of overdrive on 2nd gear.
(It was while trying to cure this fault that I thought about adding overdrive to 2nd while the gearbox tunnel was out)

My original problem is that OD will switch in and out as normal when the gearbox/gear oil is cold, once the oil is warm it will not engage.

At first I did not think too much of it and thought it was an intermittent wiring fault and though I'll fix that when I get time to take the tunnel out. After a little while longer it stopped working all together and I assumed it was a broken wire or bad contact.

Last week I thought I'd better do something about it :o

I renewed and tested all the associated wiring under the gearbox cover and checked the switches for operation. At the same time I removed the solenoid and stripped it to check the o-rings and it's operation. The o-rings looked ok so I put it back together and checked that it was pulling 2 amps as suggested here      

http://www.buckeyetriumphs.org/technical/jod/JOD1/JOD1.htm

All seemed OK so I put it back together and tried it out,  No overdrive at all  :(

In desperation I tried a new solenoid, still no change  :(


Next thing I did was to remove the OD sump and check the pre filter and magnet (both clean)
then I checked  the operating piston was moving by tuning the prop and you can see the cam turn on the mainshaft and with plug removed
you can feel it moving up and down.
Then I took out the relief valve including the fiddly bit that you hook with a stiff wire and gave it a thoroughly good clean.
Next I took out the High pressure Filter and found a lot off crud in it but at least no metal or swarf.

There was no sign of any obvious damage to any parts or o-rings so I put it all back together and filled it up with clean fresh hypoid 80w/90.

took it for a short drive and overdrive was again working. A little slow to operate (not slipping) but I put that down to the oil being cold, It has always been a little slow till the oil warms up and then engaged nice and quickly.

Of course that was a short drive and I assumed all was well, took it for a bit of a run today.....................................................

AAAAAAAARRRRRRRRRGGGGGGGGHHHHHHHHHHHHH   it's not working when it is hot  :( :( :( :( :(

When cold it was working fine or be it slightly sluggish and nothing at all once it has warmed up.

I am now suspecting the relief valve or am I missing something simple.

[Doug Paterson]

Had something similar years back on a reconditioned overdrive.

Replacement solenoids seem a bit of a lottery these days - but it is one of the things which can misbehave when hot.  

Anyhow I made 3 changes at the time - one of them did the job.  

1.  I replaced the little o-rings on the solenoid with the replacements sold by Rimmer.  These are noticeably thicker than the very thin ones which come as standard on the solenoid valve and I reckon they are bound to seal better as oil heats and thins (and that seal is surely important to the solenoid valve keeping pressure).  

2.  I secured the body of the solenoid (it did not have all its roll pins holding body to valve).  Doesn't sound like you have this problem.

3.  I replaced the EP90 (As a trial) with EP75/80.  Thinking here was if there was any crud jamming anything (be it the pressure relief valve/the pump or whatever) that the thinner oil might be more likely to flush it through.

Something worked - my OD has been faultless ever since (above was all done about a week before La Carrera 2009)

[Doug Paterson]

"standard" o-ring versus the ones I got from Rimmers (the thicker ones)

[tiggrr1]

Thanks for the suggestion Doug,

I'm guessing they are the outer o-rings and not the inner ones for the shuttle ?

[StagNL]

Before I rebuilt my J type it would take a long time to engage when hot, sometimes slip when engaging especially when exiting corners.  Found the cone clutch was worn but that wasn't the sole culprit.  Problem made worse due to engine thrust bearings had fallen into the sump causing clutch slippage.  Triumph engines I believe are notorious in regards to thrust bearings.

Once rebuilt the OD would not engage at all.  Despite working in a clean room environment, there was still something blocking the works so it was off with the OD sump and give everything another good clean.  Worked perfectly since.

Julian

[tiggrr1]

Just been on the phone to O/D Spares and had a chat to a guy called Dave (sorry didn't get his second name)

Thanks to Marcus and Gaz recommending him :)

Thoroughly nice guy who listened to my tale of woe and talked me through one or two things,

It seems (logically) that my oil pressure is to low once it warms up.
There would also appear to be an extra washer fitted above the top hat the ball valve sits in, in the pump which would reduce the pump cylinder capacity and therefore the amount of oil being pumped around the system. Which is going to mean less operating pressure once hot.
It has also been suggested by Dave to raise the oil pressure by fitting a shim or two to the main relief valve spring to up the pressure a bit.
(Marcus he reckons on a 10 thou shim adding around 30psi)

I have ordered a bottom gasket and o-ring kit which should be here by Thursday, I'll clean it all out and fit new o-rings where possible. Remove the washer from the pump & shim the relief valve. Hopefully that will sort things out.
If not a larger than expected petrol bill awaits on the 10CR  :o :o :o

[Doug Paterson]

Good luck  :)

That would be Dave Twigger - who made an appearance on the TV series "An MG is Born" as he provided an overdrive for the project car.

If I remember rightly he threw together a new OD from in no time.

D

[tiggrr1]

Just got back from the Pendlet and Pennine monthly meet.

I have found that if I put the car in overdrive and keep it in overdrive then it will stay in overdrive. If I switch out of overdrive at the end of the motorway it will not re-engage overdrive.

After the meeting I could again select overdrive run for 30 mins down the motorway and as long as I left it in overdrive it stayed there, again once I switched out of overdrive it would not go back into overdrive.

It will probably work again tomorrow when it is cold.

[GT6 M]

You have to get the new O rings on,to see if they making a diff.
Did you manage to pressure test it,!!!
you will need to make a cut oot in the chassis rail,as the rail hides the pressure plug,
needs to be,aboot 1 1/4 inch long,by the thickness of the chassis lip,   you soon see when you under neath ,  ...agen... :-/
untill ye check the PSI ,then you still shooting in the dark,
it really does seem pressure related, BUT, maybe a worn doon clutch too

you still got the old solly on,or the yan Mad Max give you,!!!

most likely,a rebuild when you get back,
Gaz,been there done it, so if he can doo it,(whistle)(whistle)(whistle)

[tiggrr1]

Only thing I can now think of is to go back to the electrics as when I bypassed the electrics before it was not working at all.

I have now also had a gasket and seal kit from Dave at OD spares and renewed every o-ring that I can get too from the sump area of the OD unit.

Still have not managed to pressure test it as I have not had enough time to do that at work but surley it is making enough pressure as the overdrive will stay in forever until I switch it out and then it will not re-engage when warm. From a cold startup it will operate normally for about 10 mins and then go all to pot. It does however take a couple of seconds after flicking the switch for it to engage, it is instant switching out. No signs of any slipping when engaging.

Got me stumped at the mo!!!

Like you say most likely a rebuild after the run

OI Gaz only did the gearbox not the OD  :P :P :P :P :P :P :P :P :P :P :P

Sill if I can through a bit of creative driving keep it in OD as it works in 2nd, 3rd and 4th we may be able to cruise on some sections.

[Deleted User]

Steve, I have the J type rebuild manual scanned if you want me to send?

Its a large PDF file?

Rob

[tiggrr1]

Please Rob :)

I may already have it but I may not :)

[Nick Jones]

Sounds like solenoid or solenoid O-rings to me.....

Nick

PS, the OD in the PI sometimes fails to enagage because sometimes the switch in the gear knob does not actually "make" when moved to the in position - usually if I've only moved it slowly.  Switching it out again and retrying with a more positive action sorts it.  There are three clicks in the engagement process on that car, a light click from the switch (if it deigns to work) a sharp click from the relay and a clack from the solenoid - just far apart to hear each......

[tiggrr1]

Cheers Nick

I have changed out the solenoid for a recon unit (maybe dodgy  :o )

Have also tried new o-rings on it with the kit of bits I got.

Seems the hydraulics are working as it stays in overdrive just does not like switching in and out when hot  :( :( :(

[StagNL]

Nick has a point regarding the switch.  I've had a few duff ones.  Maybe the heat affects the switch itself - providing yours is on the gearstick.  I magine the gearstick gets a tad warm in your car?

Julian

[GT6 M]

Yes good points about the switch.
try it just joining the wires together. as you drive.

failing that, I had an od years ago that would no go in when  hot, it was the sliding member that had gaulled up, due to main shaft tip breaking. so the shaft was flapping aboot at the od end.
but you no got a crunch going into 4 th, or  have you,!!!!!! you have, its the above.

just trying to ..prepare you for the wust,(whistle)(whistle)(whistle) ;)

[thebrookster]

796 wrote:

it was the sliding member that had gaulled up, due to main shaft tip breaking. so the shaft was flapping aboot

just trying to ..prepare you for the wust,(whistle)(whistle)(whistle) ;)

Marcus, I had never realised you had suffered such extreme problems, please accept my heartfelt commiserations.

It is a wonder what a thread regarding O/D's can end up divulging.

Cheers,

Phil

[Fizzy]

after fitting my OD recently, i was told its normal for it to take 1 or 2 seconds before it comes on, and pretty much instant coming out.

[tiggrr1]

Thanks for the suggestions Guys

Marcus,

the selection of 4th (and all other gears) is silky smooth so I'm pretty sure my sliding member is ok  ;D ;D ;D


Nick,

I'm pretty sue the gear lever switch is ok as I have tried bypassing it. Having said that Gaz does say that it is does not feel very positive in operation.

The only other thing that springs to mind at the moment is the fact that there is still the old Lucas relay mounted on the bulkhead (used for the original D-type OD) that is still wired into the system and possibly playing up when warm? I think I should do away with it as J-Type solenoids only use 2amps for operation. Or at least fit a modern relay to help protect the various switches in the circut.                                                                                          

[Tim Bancroft]

I had a similar problem like this years ago with my J type overdrive (2002 RBRR), ended up being a worn inhibitor switch. The bracket on the end of the remote gearchange unit needed abit of adjustment and a new switch solved the problem.

Not saying its def the answer, but have a look at the ball bearing in the switch and see if its worn.

Steve, I hope you sort this problem.

[tiggrr1]

Thanks Tim

The inhibitor switch is making and breaking the circut at least when cold but obviously I have not checked this at speed on the road.
I think I need to try one more drive with the solenoid wired direct to the battery via a switch and fuse as I think last time I tried I had no OD at all. (possibly I had refitted the pump non return ball valve incorrectly)

If not then we WILL be doing the 10CR minus overdrive  :) :) :)

[Deleted User]

tiggrr1 wrote:

If not then we WILL be doing the 10CR minus overdrive  :) :) :)

you can't use overdrive towing me anyway mate :P