Overdrive clutch type

Post by **Rev Light** » Sat Jun 15, 2019 8:41 am

I understand, rightly or wrongly, that when an overdrive is engaged by the solenoid, that it is done via some sort of clutch arrangement. What type of clutch is this? Is it a disc with some sort of friction material, or some sort of centrefugal arrangement?

The reason, I ask, is that my overdrive is no longer engaging properly. It does a couple of times when cold, but drops out when it warms, never to return. I tried to top up the oil, but it wasn't that low and I barely put half a litre in. I am about to drop all the oil and replace it. I suspect that an additive might have caused an issue, although it's taken a couple of years to do it.

Regards

Steve

Post by **scimjim** » Sat Jun 15, 2019 8:52 am

It’s a cone - with friction material. Sounds like it could be low oil pressure? I’d do an oil change first.

halfpenny · Post by **halfpenny** » Sat Jun 15, 2019 9:03 am

Have you checked the gearbox oil level?

Post by **Rev Light** » Sat Jun 15, 2019 9:30 am

Topped it up yesterday. The oil that overflowed has a definite grey colour to it. It's the only reason I mentioned additive, as I do not remember adding any. I did to my back axle, but for a different reason - not that it did any good. The books categorically says not to add anything to the oil in any overdrive gearbox.

Anyway, fresh oil sourced, car warm and up on ramps, time to drop the oil.

Cheers

Steve.

Post by **TrevorG** » Sat Jun 15, 2019 9:42 am

If you have no luck, or if you want to do this prior to oil change....you can take the plate off the bottom of the overdrive unit and check the magnetic strip, the base filter, and if feeling strong, the pump filter. It's amazing how much crud gets there and affects the pressure.

halfpenny · Post by **halfpenny** » Sat Jun 15, 2019 11:02 am

Also pull out the pressure relief valve and clean it up; these can get very mucky and sticky.

Post by **scimjim** » Sat Jun 15, 2019 11:19 am

Pretty sure the magnetic strip and pressure relief valve were cleaned when the box was replaced 18 months ago wasn’t it?

Post by **Rev Light** » Sat Jun 15, 2019 11:22 am

If the chunks of metal that fell out of my overdrive sump are anything to go by, then I thinks it's toast.....

Ho hum....

Post by **scimjim** » Sat Jun 15, 2019 11:45 am

Oops - yep, that’s toast!

Post by **Rev Light** » Thu Jun 20, 2019 5:24 am

Last question, I suppose. ..
Am I at risk of losing drive all together?
I had planned to take it to France at end of next month. I am planning to go to the Somme via L'Havre, avoiding the major routes.
Cheers

Post by **willholderogri** » Thu Jun 20, 2019 6:19 am

That looks like a piece of thick wire .

Post by **willholderogri** » Thu Jun 20, 2019 6:20 am

Some sort of pin maybe that has been mangled

Post by **willholderogri** » Thu Jun 20, 2019 6:22 am

Closer look seems to be the remains of a thrust washer

Post by **Rev Light** » Thu Jun 20, 2019 8:50 am

Anyway, I drove it work this morning. 36 miles across the downs from Swindon to Bradford On Avon.

halfpenny · Post by **halfpenny** » Thu Jun 20, 2019 9:02 am

Send the photo to Dave Twigger at Overdrive Services in Rugby. He'll likely identify it for you, and the consequences.

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