Overdrive

[VanIsleSprint]

Is it possible to remove the J type overdrive from the Sprint gearbox
in the car. I have a problem with mine not engaging. Oil level is good,
solenoid operates. I'd rather not pull everything again.
thanks,
Doug

[80Sprint]

Doug.

Generally no but a few on here say you can but probably as difficult as pulling it all out. It's not as simple as just pulling it back after unbolting as it will foul the chassis.

I assume you have had the solenoid out and can see it moving ? I would also clean out the filter and blow the oil ways out to make sure you don't have an issue there.

Good luck.

[trackerjack]

The outer solenoid casing is held on by little tiny pins, these pins gradually elongate the holes which has the effect of moving the solenoid back.
In conclusion the solenoid appears to be working but is in fact not moving far enough to engage the overdrive.
I hope I made sense.
The cure is to make those holes accurate again.
I deformed my casing with delicate use of a small hammer to put back metal where it had been removed.

[cliftyhanger]

Have you checked the seals on the solenoid? Pair of o rings IIRC. Easy enough to try. And another vote for trying the filters, some had a habit of getting blocked.

[Jon Tilson]

I tried pretty hard to refit an o-d to a Sprint box when it was in the car, having made the mistake of fitting the box first. In the end I gave up...

It works on an 1850 single railer, but not on a Sprint box.

Some folks say you can do it by dropping the sub frame a tad....

I'm too old now to heave boxes about from inside, so I pull the whole lot on a crane and split the exhaust at the bottom of the downpipe.

Jonners

[VanIsleSprint]

Some history leading up to my problem. A few years ago I rebuilt the gearbox with a kit from a well known Lincolnshire supplier. All as fine until last April when we tried to go to Victoria for an event.
I found it very difficult to shift from first to second and the gearbox was noisy in neutral with the engine running. I went to a friends
place, who has a hoist, and we drained the gearbox and overdrive and found much metal in the fluid. We suspected the lay gear bearings
had gone and this rather confirmed this. We replaced both filters and fluid however the overdrive still did not engage.I then removed
all components s that are accessible from underneath and cleaned them as well as replacing the O rings. I found the pressure
relief valve very sticky and after freeing this off, the overdrive began to work again. This winter we disassembled the gearbox to find the lay shaft
was not properly hardened (it could be marked with a file on edge) and the lay gear bearings had disintegrated. We replaced the lay shaft,
bearings and rear main shaft bearings with parts from TRF in the US. At this point I replaced the O rings on the pistons, rear seal and O rings
on the solenoid. The solenoid is solid with no movement and operated correctly. I am now suspecting the pressure relief valve again and my
next step is to measure the operating pressure which should be around 400 PSI. If this is too low, I think either there is a problem with the pump
or the pressure relief valve is not seating properly. Have I missed anything?
Thanks,
Doug

[Carledo]

I don't want to suggest incompetence, but you did replace the drive eccentric on the mainshaft on reassembly didn't you? I've seen these left out by competent reconditioners in the past!

Steve

[VanIsleSprint]

I'm pretty sure we did, but I can pull the inspection plate on the overdrive and undo the plug under the pump.
If we then turn the engine over in gear I should be able to see the plunger moving. Good point Steve.
Doug

[Jon Tilson]

Ive done a few Sprint boxes in my time but in all cases the layshaft has been fine so Ive just changed the bearings.

Looks like that was a good decision!.

Wittor here does them but wants an arm and a leg - standard for him I guess..

So did you get anything from them for your inconvenience or did they just send you another bar of chocolate?

Your learning the hard way why most of us now use them only for guaranteed NOS OE or as a last resort.

One of their guys used to come on here from time to time but I guess he got too embarassed - after promising much
and delivering zip.

Jonners

[VanIsleSprint]

It seems you were on the right track Steve. I had the bottom plate off today and the plug under the pump out.
Turning the engine over in third gear on the starter and there is no movement on the plunger. Somehow the cam
must have moved when the overdrive was mated up to the gearbox. I guess I should have checked this before
installing the whole engine gearbox unit. I mated the overdrive vertically to he gearbox. Is it better to do it
horizontally.
Doug

[Henk]

Should make no difference, the cam shouldn't slide that easy over the main shaft!

[Carledo]

No, it shouldn't move at all! A lip at the gearbox end stops it moving forward, a circlip stops it moving back and a woodruff key stops it turning independently. So either the keyway has failed or it's plain not there!
I always mate the O/D unit vertically and have never run into problems. The only precaution I take is turn the 3rd motion shaft till the thickest part of the eccentric is towards the top of the box, reducing as far as possible the risk of damage to plunger. And needless to say, the chamfer on the eccentric faces the overdrive unit.

Steve

[VanIsleSprint]

well, after separating the OD and gearbox, I found the cam was not turning with the mainshaft.
Then I noticed the woodruf key in the bottom of the casing.The pump plunger was not moving smoothly
so I removed the plunger and body and cleaned them up with 600 then 1000 paper. After reassembly
with grease, the plunger now moved smoothly with the mainshaft. Hmmm.
Doug

[trackerjack]

Well done Doug,
Its good to read a thread where the main guy updates as to the real fault.

[tony g]

The question is was the key always left in the case since it was built or did it fall out after being fitted? If the latter something may be amiss still.

Tony