J Type overdrive issues

[Radders]

I need help! (Not professional-I've had that-it doesn't work!  ;))

The overdrive on my Mk2 estate works fine when cold, but once the car has warmed up it refuses to go in! On the rare occasions that it does go in I get a 'clutch slipping' feeling?

I know nothing about these gearboxes so any suggestions would be helpful.

The gearbox oil was checked before the HCR and the car hasn't been used much since then. I will be checking it again this weekend, but  wondered if there's anything else I can check whilst under the car?

Thanks in advance.

[mikew]

391 wrote:

The gearbox oil was checked before the HCR and the car hasn't been used much since then. I will be checking it again this weekend, but  wondered if there's anything else I can check whilst under the car?

Thanks in advance.

Check the overdrive sump and filter for debris, its the rectangular alloy plate with 6 bolts - remove it, and clean the magnetic traps and the filter above.

is it A or J type ?

Check the actuating lever adjustment - detailed in the manuals and in an earlier recent post on here

mike

[piman]

Hello Radders,

not so familiar with the 'J' type, but I'm wondering if your oil pressure relief valve is passing, I'm thinking you are losing pressure as you say when hot it doesn't work and seems to slip when it does go in?

Alec

[Radders]

piman wrote:

Hello Radders,

not so familiar with the 'J' type, but I'm wondering if your oil pressure relief valve is passing, I'm thinking you are losing pressure as you say when hot it doesn't work and seems to slip when it does go in?

Alec

Correct. So where is this valve? I have a spare gearbox I could rob one off I think.

[sparky_spit]

Also, while you have the rectangular alloy plate with 6 bolts off, you will see 2 (or maybe 3) circular caps with 2 holes in each. Under one will be the pressure relief valve, which can be cleaned, and under another will be a small cylindrical filter (looks like a baby K&N breather-pipe filter). This has fine wire gauze and can be cleaned in petrol. On 2 ODs I've "serviced" these were absolutely full of crap and must have been inhibiting oil flow. You are supposed to use a pin wrench to get these caps off, but I used a pointy pair of pliers held in some molegrips to get them undone.

[StagNL]

Ah, the J type, just what I have been mucking about with this spring....

Works when cold but not hot, or slips when hot - could be all sorts related to the OD unit itself but it could be made worse by engine crankshaft thrust bearings on their way out.  Mine slipped when hot under acceleration - rear engine thrust bearing was in the sump and crank had eaten into the block - end float was 3mm rather than the required maximum of 0.28mm.   So that wasn't the OD but the regular clutch slipping - which was strange as it only occured with OD engaged.

As Sparky implies, there are all sorts to service under these units.  Can all be done with unit in-situ but jacking up the car a tad will help to create space to work in.  
First off, check the gearbox oil level.  OD shares the same oil and suffers if level is too low.
Then check the solenoid is working properly.  It should draw around 2 amps when activated.
Rectangular alloy plate in the OD sump, take that off and you'll also get a quart of gearbox oil come out with it - just warning you so that you won't be surprised.  Ease off the bolts to get the oil running out and leave for half an hour or so.
Pull off flat filter and clean.  There are now 3 caps visible.  Access to these is via a special tool that has two pins but if you have the means you could make your own.  The right one houses the cylindrical filter, the centre one has the oil pump non-return valve - carefull here as there is a small ball and spring that can fly out and easily get lost.  Left cap houses the oil pressure relief valve.  This can be a little tricky to pull out and while there is an official tool one can get by with a thin hook-like device.   All this stuff behind the sump must be clean - very clean - as any small bit of grit will cause things not to work.

From what you describe, the oil level and solenoid would be my first checks.  Then a good clean of the oily bits behind the sump.  If that fails to have effect, check the hydraulic operating pressure which is done by removing the bolt just forward of the solenoid and fitting a special oil pressure gauge.  Maybe someone (private or commercial) near you has one or you might be able to fashion one by sticking bit of this and that together.  I know one was built by adding a gauge to a length of flexible brake line.   I got mine from a guy in the US for a reasonable price.  Oh, checking the pressure is done with the gauge sticking up into the car if the hose is long enough and driving it or raising the rear wheel off the ground and running it up around 30mph.

More info, scroll down for more pages: http://www.buckeyetriumphs.org/technical/jod/JOD4/JOD4.htm    

Julian

[Radders]

Thanks for the replies fella's.

I shall be having a go at this tomorrow afternoon!

I'll let you know how I get on.  :)

[Doug Paterson]

I similar symptoms on a nearly new (well recon) J-type.  Fine cold but stopped working once hot.

I did 3 things at the time (one, or a combination of the three fixed the problem).

1.  Changed the EP90 for EP75/80 (for a trial period).
2.  Fixed the casing of the Solenoid .... one of the little roll pins which secures the body to the valve had dropped out allowing the body to move when the OD was engaged.  In theory refitting the roll pin to secure the body would allow the valve to work more positively.
3. replaced the o-rings on the solenoid valve for thicker ones (the ones Rimmers supplies are a bit thicker than the ones which came with the recon OD.

I've had no problems since .....

D.

[Radders]

well, seeing as it was a nice evening (and that there was bugger all on Tv) I decided to have a look.

The oil level was fine (In fact it started running out as soon as I undone the filler)

So I undid the sump. The filter looks fine and the rest of the parts looked clean abd grit free too. I will give them a proper clean tomorrow and refit them. (Although I need a new gearbox sump gasket-any idea where I can get one of these?)

It looks like the solenoid will need to be next on the list for a checkover.   :-/

[StagNL]

391 wrote:

(Although I need a new gearbox sump gasket-any idea where I can get one of these?)

If you have the luck I had during the two times I pulled off that sump, you'll be able to get it back together with the original gasket - even without sealant!

Or is yours stuffed beyond re-use?  Maybe Overdrive Repair Services can help: http://www.overdrive-repairs.co.uk/
I got my rebuild kit from them so I guess they stock loose gaskets too.

Let us know how you get on with that solenoid.  Also remember to be squeaky clean with those other parts.  Somewhere I have a flow chart check list thingy for OD problems.  If you want a look-see I can fish it out of the system or scan the copy I have.
Do you have any diagrams depicting the OD innards?  They can help to check if you have pulled everything off from underneath.

Julian

[Radders]

699 wrote:

If you have the luck I had during the two times I pulled off that sump, you'll be able to get it back together with the original gasket - even without sealant!

Or is yours stuffed beyond re-use?  Maybe Overdrive Repair Services can help: http://www.overdrive-repairs.co.uk/
I got my rebuild kit from them so I guess they stock loose gaskets too.

Let us know how you get on with that solenoid.  Also remember to be squeaky clean with those other parts.  Somewhere I have a flow chart check list thingy for OD problems.  If you want a look-see I can fish it out of the system or scan the copy I have.
Do you have any diagrams depicting the OD innards?  They can help to check if you have pulled everything off from underneath.

Julian

Nope! Didn't have the luck. The gasket is split  :(

I dont have diagrams at all, so any diagrams or flow charts would be most helpful.  :)

Thanks

[StagNL]

Check this out.  Specifially for Volvo but the actual OD unit is the same.  Lots of nice pics for you to gander at and also a fault finder checklist:
http://volvo1800pictures.com/document/Service_manual_jack/part_4_43b_overdrive_type_J/part_4_43b_overdrive_type_J.pdf
Another fault finder list:

[Radders]

Finally found the time to have a look at this. Both solenoids I had were working fine, but the overdrive stopped working altogether on the way over to the Essex meet the other week!

The switch on the top of the gearstick was changed tonight and hey presto! all working fine again! I didn't have a chance to let it get warm to see if it would still work then as I ran out of petrol a mile away from my house! Doh!  :B

I will be going over to get some paint made up on Saturday morning so I'll take it out again then. And put some petrol in it first!  :)

[StagNL]

391 wrote:

The switch on the top of the gearstick was changed tonight and hey presto! all working fine again!

Speaking of these switches, Am I the only one to appalled by the quality of the ones available?  Bought two, first replaced the 35 yr old broken one and it failed in less than 6 months, the second bought as another replacement also stopped working correctly PDQ.  I eventually had to prod about with a hot nail to melt some plastic to get it to work.

Julian

[Radders]

Ok, test drive completed-still bad news!  :(

I think I have two problems with this. One was the switch, which is now resolved, but I still have the problem of the overdrive not coming in the gearbox is warm.

When I flick the overdrive in when driving it doesn't go in, but you can feel the car vibrating? As if its trying to go in but something isn't letting it. As soon you flick the switch to take the overdrive back out, the vibrating stops!

I'm begining to think this problem is more to do with pressure rather than electrical. Any suggestions?

[StagNL]

I take it the filters and what-not have been clean carefully?  While you were doing that, did you also pull out the non-return valve and relief valve/dashpot assy for throrough cleaning?  
If so and you are sure of it, it may mean that something inside is broken - maybe the clutch ring.  Seeing as the unit fails or slips in OD engaged mode, that would make sense - the damage then being on the outer diameter of the clutch ring - as I found on mine.
Do you have any possibility to perform a pressure test on the unit?  If you can then that may point away from actual mechanical damage.

If you do end up needing to replace or repair the innards, you'll need to remove the gearbox from the car.   The most difficulty I had was getting the OD unit off the gearbox, the actual rebuild was a doddle.

Julian

[Radders]

I have a spare OD unit on another gearbox, so I'm inclined to just swap the entire unit over.

I'm assured it can be done without removing the gearbox from the car? Its a Mk2 estate.  :-/

[StagNL]

I've heard that it may be possible to remove the OD unit with the 'box in situ, however when told this I was also told that I'd be very lucky if I actually managed to do so.
In my case I had the whole lot (engine and 'box) out anyway.  Still, I had to hang the transmission by the OD output flange from a crane and much whacking with mallets and blocks of wood ensued.  
If you can find leverage between 'box and OD, you may be in for a better chance than me.  By all means try as it isn't going to harm anything if it doesn't work.

Julian

[Radders]

Well, I started removing the ovedrive unit tonight while it's still in the car. I've managed to get it about an inch apart, (I've split it between the OD unit and the adaptor plate on the gearbox) but just can't get it to split any further!

Am I missing something?

[Doug Paterson]

391 wrote:

Well, I started removing the ovedrive unit tonight while it's still in the car. I've managed to get it about an inch apart, (I've split it between the OD unit and the adaptor plate on the gearbox) but just can't get it to split any further!

Am I missing something?

There is a procedure to follow on the road to ensure the OD is not gripping the gearbox's output shaft - I don't recall but it is covered in the Hayne's manual.  Hopefully this isn't the cause of your problem as its a bit late.... fingers crossed.

Its much easier to split with the full gearbox assembly out of the car .....

[Radders]

I've just read the Haynes manual and according to that, the overdrive should just slide off once the eight nuts are undone.  :-/

[TedTaylor]

391 wrote:

Am I missing something?

You're not using a big enough hammer ;D

Ted

[StagNL]

Factory supplied ROM says that it helps to raise the rear wheels off the ground, run the engine and transmission, engage OD and then disengage with the clutch depressed.  What this does is release the spline loading between planet carrier and uni-directional clutch.  There is also talk of energizing the solenoid and pumping oil in but you've already split the two further than what they say.
Don't worry, I read that AFTER I had removed the gearbox assembly and still got it off.  I think Ted has the answer, though he may have typed that in jest.  I had to whack it really hard - held a piece of 4x2 wood up against the 'box and gave it mulitple whacks.   Bit by bit it came loose.
At 1 inch I reckon you are nearly there.

Julian

[TedTaylor]

699 wrote:

I think Ted has the answer, though he may have typed that in jest.

Yes I did and was suitably admonished on the Register Forum. :B  However it is nice to know that my idiocy was not without some foundation!

There were some very good technical pointers about this on the Register Forum which I will put into the Forum Notes that I do for the Register's Mag 'Six Appeal'.

Ted