Overdrive a no no

[GT6 John]

Potted history of my overdrive:

Upgraded about 2 years ago to an overdrive gearbox.  Bought the gearbox reconditioned off a fine fellow in the local TSSC.

Didn't really drive the GT6 for much of last year - various reasons too boring to recount here.

Only really driven the car with the o/d 'box for a year, if that, accordingly.  Halfway home from the IoW TSSC camping trip it started dropping out, then going in, dropping out, going in and then dropped out and that was that.

Switch on column is fine.  All connections good.  Thought, aha it's the solonoid.  New solonoid fitted, quick test drive... it works, huzzah.

Halfway home, starts dropping out, going in etc. then drops out completely.  There is still a click if I flick the switch, but no o/d.

Now I have heard that sometimes the 'pistons' (?) can wear on the D-Type and when they do it can cause these sort of symptoms.  Is my o/d a terminal case or is there another cheaper possibility?!

[DaveKent]

have you checked the oil level in the gearbox?

[GT6 John]

Sorry, meant to say about that as well. Yes, oil level is correct.

[Velocita Rosso]

D type ?Have you:
Cleaned the oil filter out?
Had the inspection plate off the side and adjusted the operating cam?

[Velocita Rosso]

Now , if you havnt:
Clean the filter of sludge and muck and bullets
Take side plate off, line up the two holes in the cams, with a matching diamete drill bit and adjust the lock nuts
This should allow the o/d to, operate quicker, stay in and work

[GT6 John]

Yes, I had my man do the matching diameter drill bit trick whilst changing the solonoid!

This is why I'm wondering if it's a more serious internal issue.

[Vitesse2l]

Isn't there a procedure for re-seating the ball bearings?

I recall they can leak and lose oil pressure.

Or am I remembering complete tosh?

Cheers! Steve B

[Tim Bancroft]

Check that that inhibitor switch is'nt worn, had this problem with my overdrive. Its a ball bearing that moves around and if worn can result in switch malfunction.

Really simple to check.

[Jason]

timbancroft61 wrote:

Check that that inhibitor switch is'nt worn, had this problem with my overdrive. Its a ball bearing that moves around and if worn can result in switch malfunction.

Really simple to check.

Likewise the mounting bracket - I had a similar issue on the Vitesse, fixed with a hammer at 3am in German car park on a 10CR - you don't need to do it in a car park but speaking German really helps :-)

Dodges with the inhibitor switch includes bending and/or re-welding the bracket, taking out the fibre washer and refitting the switch to allow the ball to sit a fraction closer to the contact arm or rolling the ball around with a little lubrication (cue smut). Oh and I think you can swap it with the reversing light switch too - better to have a flickering reversing light than a flickering overdrive!

Also, check the wires for brittle insulation and breaks, if they look or feel dodgy, replace them - I had one once that was broken inside the insulation, when I cut it open it was corroded and falling apart yet on the outside looked OK it did feel a little crunchy though.

[Velocita Rosso]

Other than all the above ,or taking it to pieces on the dining room table, I would suggest ringing Peter at Overdrive Services and give him the symptoms.
Hes a really good guy, ex Laycock, and he would probably advise what is what. They are just a few miles from us and used him before

[GT6 John]

So buying a new inhibitor switch and changing it sounds like the quickest and cheapest option.

Why do I hear a click when stopped and listening for it when I flick the lever if the switch on the box is failing?  I suppose when stopped the ball bearing isn't vibrating / bouncing so stays in place?

Loose balls seem to be an agreed potential problem.  I'll lubricate well, have a fiddle and if all else fails I'll order a new switch! ;D

Smut-o-meter is off the scale!

[sparky_spit]

A quick test to check if it's the inhibitor switch or not would be to take both wires off and join them together. Then take it for a drive and see if it's "fixed". Obviously, don't forget that overdrive will now work in 1st, 2nd and reverse, so be careful not to use those gears with overdrive engaged.

[rotoflex]

Listen for the location of the click.
If it's the overdrive relay clicking, the OD solenoid is not necessarily engaging.
If the OD solenoid is engaging, then the inhibitor switch is OK.

Trying to clarify:
Is the click you're hearing coming from the OD relay, or the OD solenoid?

[Tim Bancroft]

Totally agree with R'flex.

Sounds like it maybe an issue with the o'd unit.

[GT6DavidMK1]

Could the O/D unit be tired and the oil pressure will start falling when it gets warm  ;) There is a way of improving it but you will have to ring me, to explain how to do it ;D far to hard to write it out.................. :)
And just another thought you have got the correct grade of gear oil in the gearbox (EP90)?


David.

[GT6 John]

I'm confuzzed as usual.  I thought we'd agreed it was possibly a dodgy inhibitor switch?  OK, it may turn out not to be, I'm not holding you to it! :P

Now you're saying that possibly it is worst case and the o/d internals have packed up!

Yes it's EP90 in there.

I'll be phoning David on Tuesday! ;D It is fine when cool, 10 or 15 minutes into a journey and it's all warmed up is when it drops out, so David seems the closest to what is happening with it.

If I have to buy a reconditioned o/d unit I will (Canleys will be pleased!) but I'd like to exhaust all other and cheaper possibilities first! ;)

[Nick Jones]

GT6DavidMK1 wrote:

Could the O/D unit be tired and the oil pressure will start falling when it gets warm  ;) There is a way of improving it but you will have to ring me, to explain how to do it ;D far to hard to write it out.................. :)
And just another thought you have got the correct grade of gear oil in the gearbox (EP90)?


David.

I'm with David on this one.  Cleaning the filter gauzes may help a bit, dunno what his other cunning plan is  :P

Nick

[Pete Lewis]

the Dtype solenoid has 2 coils inside, fed from a relay ,there's a main pull in coil that uses 10amp and a switch in the sealed end of the solenoid that cuts this current and drops in a coil of 0.5amps, when fully engaged, the solenoid does not travel very far to do all this,  under the cover  if the lever and holes line up with the power on and the current drops from 10 to imediately 0.5a   try to fit a simple meter in the feed wire and see whats going on.
  
reseating the ball in the vertical valve on the top of the case is to give it a light tap with a small punch..
make sure the small hole in the hollow pushrod inside this top valve is clear ,   Pete

[GT6 John]

Tried a few ideas from you people above.  Many thanks for all your tips and advice.  Thing still drops out.  It's knackered. New (reconditioned) one will be ordered when I get a moment.

I can see why 5th gears caught on.  Blimey, what a load of hassle just to get an overdrive working! Probably the frustration talking but kudos to the Type 9 upgrade people out there! :P