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special sport gearbox.

qantasqf1
Posts: 299
Joined: Mon Mar 07, 2016 10:13 pm

Re: special sport gearbox.

Post by qantasqf1 »

Certainly! Give it a go.
Steve

Stan Thomas
Wise Man
Wise Man
Posts: 795
Joined: Sat Feb 13, 2016 2:14 pm
Location: Penkridge. Staffs.

Re: special sport gearbox.

Post by Stan Thomas »

Subject - Correct flushing of epileptic-cyclist gearboxes.

Take the car on a run first to get the gearbox to operating temperature, then drain off the oil.

Put in your solvent, (about half normal capacity will do) then run the engine for a minute or so in neutral to wash all the planetary gears, pump and oil drilling in the mainshaft, then quickly select and engage all gears, but only for a few seconds each. There will be an adequate amout of residual oil mixing with the solvent to provide sufficient lubrication whilst the gearbox is off-load.

Drain off immediately, and the hot gearbox will evaporate any remaining solvent, then leave everything to cool completely before refilling with straight 30 grade engine oil, and run the engine and select each gear in turn for a few moments to ensure the fresh oil is fully distributed before going under load by driving off.

P.S.
Don't forget to put in fresh oil, otherwise your gearbox will go Eeeeeeeeeeeeeeeeeeeeeekkkkkkkkkkkkkkkkkk and sieze up.

davidian
Posts: 99
Joined: Sun Feb 17, 2019 11:32 am
Location: la vinuela spain

Re: special sport gearbox.

Post by davidian »

Thanks for the advice Stan. There is motor oil warehouse on the local industrial estate, would you recommend mineral or vegetable based oil ?
David.

Stan Thomas
Wise Man
Wise Man
Posts: 795
Joined: Sat Feb 13, 2016 2:14 pm
Location: Penkridge. Staffs.

Re: special sport gearbox.

Post by Stan Thomas »

Hi Davidian,

Must be mineral based oil!!!!

davidian
Posts: 99
Joined: Sun Feb 17, 2019 11:32 am
Location: la vinuela spain

Re: special sport gearbox.

Post by davidian »

Hello.
Have drained oil then filled with about four pints of turps then let it tick over in neutral for a minute or so . Dont fully understand how top gear engages, does it rely on a bit of centrifugal force to engage , if so I will need to raise the back of the car to allow the wheels to turn when top is engaged . Sorry Stan , I meant to say Synthetic,not vegetable oil. its like saying Real Madrid or Artificial Madrid.
David .

Stan Thomas
Wise Man
Wise Man
Posts: 795
Joined: Sat Feb 13, 2016 2:14 pm
Location: Penkridge. Staffs.

Re: special sport gearbox.

Post by Stan Thomas »

Hi Davidian,

Use only a straight S.A.E. 30 grade mineral oil in the gearbox - which is sold over here as "classic car" engine oil - so hopefully there will be something identical where you are.

From your latest post, it appears your problem is still there - and no, you don't have to run the car as part of the top gear engagement process.

So lets get something right to start with. You have an overdrive gearbox - so is top (not overdrive) a staight lock-up multi-plate clutch like standard Consort/Conquest gearboxes? Can any Special Sport owners confirm please?? I only have service info for the Conquest range.

Do all other gears work O.K. including overdrive?

Why I ask is because all gears except top have brake bands which rely to some degree upon a servo-effect which can show symptoms of slow or dragging upon engagement if not correctly adjusted - but not top gear. Top gear is a steel multi-plate clutch which is engaged by a sort of helix arrangement (like a very coarse thread) - so it should engage directly upon return of the the gear-change pedal.

I await clarification of the above- then we can delve deeper.

qantasqf1
Posts: 299
Joined: Mon Mar 07, 2016 10:13 pm

Re: special sport gearbox.

Post by qantasqf1 »

OK! The Special Sports gearbox overdrive is operated by a conventional epicyclic gear while top gear is a multi plate clutch exactly as employed by the Consort, Conquest, DB 18 saloon cars. The Special Sports top gear is operated by actuating an outer hub which features 3 helical grooves. This hub rotates against a stationary inner member with similar helical grooves, the 2 members’ helical grooves separated by 6 ball bearings. Rotating the outer hub by operation of the gear selection pedal moves it rearwards by virtue of the helical grooves and compresses the clutch plates. Simple, but very effective!!
Steve

davidian
Posts: 99
Joined: Sun Feb 17, 2019 11:32 am
Location: la vinuela spain

Re: special sport gearbox.

Post by davidian »

Thank you Stan and Steve.
All other gears select and engage, although reverse is a bit fierce , if I am in overdrive ( which occupies the space where 3rd would normally be) but have top selected when the gear change pedal is depressed and raised for top, the engine will rev but no drive, if I then release the throttle and rev again drive takes up or sometimes its still in overdrive, I dont think it is a selection,between gears problem because the pedal does not come back with force , the same thing happens from second to top , if I let the revs die it will engage . All will be revealed when I put in the new oil, lets hope a good clean will effect a cure.
David.

qantasqf1
Posts: 299
Joined: Mon Mar 07, 2016 10:13 pm

Re: special sport gearbox.

Post by qantasqf1 »

David, overdrive is supposed to occupy the upper position of the selector quadrant. The gears on your quadrant should read R - N -1 - 2 - T - O.
Steve

davidian
Posts: 99
Joined: Sun Feb 17, 2019 11:32 am
Location: la vinuela spain

Re: special sport gearbox.

Post by davidian »

Hi Steve.
Yes my quadrant reads R N 1. 2. T .O but if you watch the sequence of gears changing with the lid off then O occupies the space where 3 would be on a non overdrive box . I see that top has an automatic adjuster like the other gears although it does not rely on a brake band to work, could it just need some adjustment . Have now re-filled with fresh oil and will road test tomorrow to see if there is an improvement.
Regards David.

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