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special sport gearbox.

davidian
Posts: 25
Joined: Sun Feb 17, 2019 11:32 am
Location: la vinuela spain

special sport gearbox.

Post by davidian » Fri Jul 12, 2019 1:38 pm

Hello.
My car is fitted with the awful overdrive gearbox ( wont climb hills ) and although all gears engage there is a delayed action in top, both changing up and down . I have removed the top cover in order to observe what goes on in there but you can not tell if the adjusters are working because the tail pins are welded to the cover and not in the gearcase like the Conquest box , has my box been adulterated?
Regards
David

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qantasqf1
Posts: 115
Joined: Mon Mar 07, 2016 10:13 pm

Re: special sport gearbox.

Post by qantasqf1 » Fri Jul 12, 2019 8:44 pm

No, it hasn’t been ‘adulterated’! The tail pins are indeed welded to the cover.
Steve

davidian
Posts: 25
Joined: Sun Feb 17, 2019 11:32 am
Location: la vinuela spain

Re: special sport gearbox.

Post by davidian » Fri Jul 12, 2019 10:12 pm

Thank you Steve. My car has had some unwelcome attention in the past , I thought the lid might be another one.
I owned a Conquest in the mid sixties and still have the factory workshop manual which covers the gearbox in great detail.and on the Conquest you can remove the cover and observe the adjusters moving , not so on this box , you would have to put a pencil mark on the adjuster, replace the lid , pump the pedal,then remove the lid again and unless the movement is great you possibly wouldn't know if it moved or not ,but that apart I cant find any reference to my problem of the delayed engagement of top gear all other gears engage as soon as the pedal returns . Has anyone some thoughts ?
David.

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qantasqf1
Posts: 115
Joined: Mon Mar 07, 2016 10:13 pm

Re: special sport gearbox.

Post by qantasqf1 » Sat Jul 13, 2019 12:05 am

The top gear engagement mechanism is entirely different from all the other gears (I assume we’re actually talking about top gear and not overdrive - they’re often confused with each other). Top gear doesn’t use either an epicyclic or a brake band, it uses a multi plate clutch which locks the input and output driveshafts together. If top gear doesn’t slip when it’s engaged then I would guess adjustment is OK. Given this it’s possible the helixes machined in the hub, the balls and/or the clutch plates are sticky or the clutch plates’ teeth are worn. It may be worth while draining the oil and refilling the box with kerosene - sorry, ‘paraffin’ - and running the engine at idle while operating top gear repeatedly to loosen any crud contaminating the plates. Paraffin won’t damage the internals, and it MAY fix the problem. I can’t think of anything else that may give rise to this lazy top gear action, but someone else may have other (and better!) theories.
Steve

Stan Thomas
Posts: 509
Joined: Sat Feb 13, 2016 2:14 pm
Location: Penkridge. Staffs.

Re: special sport gearbox.

Post by Stan Thomas » Sat Jul 13, 2019 8:16 am

The previous post is very sound advice - and indeed what was the standard procedure in the workshop before any further action when attending to a defective gearbox.

Although a small possibility, it could be someone has put the wrong oil in the box which will adversely affect top gear engagement, as the steel top gear clutch plates will slip until all the (wrong) oil has been extruded from between them.

If Mosses had come down the mountain with eleven commandments, the last one would have been "Thou shalt not use any oil in your gearbox other than a straight 30 grade".

Let us know how you get on.

davidian
Posts: 25
Joined: Sun Feb 17, 2019 11:32 am
Location: la vinuela spain

Re: special sport gearbox.

Post by davidian » Sat Jul 13, 2019 10:39 am

Hi All
I must admit I have never drained the box in my 12 years of ownership so crud in the internals sounds probable , the downside is I cant get paraffin here in Spain, would Diesel be O k ?.
David.

grahamemmett
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Joined: Mon Feb 08, 2016 8:12 pm
Location: Northwich, Cheshire
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Re: special sport gearbox.

Post by grahamemmett » Sat Jul 13, 2019 5:31 pm

I wouldn’t use diesel but fresh oil will help.
Graham Emmett
Northwich, Cheshire
Joint DB18 Registrar (with Marcel Renshaw)
DB18 1949 LCV522 (Yes that one with the P100s)
https://www.db18.org

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qantasqf1
Posts: 115
Joined: Mon Mar 07, 2016 10:13 pm

Re: special sport gearbox.

Post by qantasqf1 » Sat Jul 13, 2019 7:53 pm

I can’t see why diesel shouldn’t be used- after all, diesel is a very thin oil. However, it may not be a particularly good solvent, but worth a go!
Steve

pekkak
Posts: 24
Joined: Fri May 13, 2016 7:26 am
Location: Espoo, Suomi - Finland

Re: special sport gearbox.

Post by pekkak » Sun Jul 14, 2019 8:54 am

Diesel contains plenty of chemicals including paraffin. Paraffin probably is just paraffin. Right?

davidian
Posts: 25
Joined: Sun Feb 17, 2019 11:32 am
Location: la vinuela spain

Re: special sport gearbox.

Post by davidian » Sun Jul 14, 2019 12:50 pm

Hello Readers.
I can easily get turps , this is a solvent and like kerosene has no lubricating quality and would be drained from the box after it has done its job , what do you think?.
David.

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