Please visit the Club's website https://www.dloc.org.uk/ to join. Visit https://www.dloc.org.uk/adhoc to DONATE towards the cost of the forum.
Please don't post someone's email address to avoid it being harvested by spambots and it's against GDPR regulations.
Always look at "ACTIVE TOPICS" to see all posts in date & time order as they are sometimes moved; or look at "Your Posts".
Please add Reg. nrs. when posting a photo or anything about a car as this will help searches. Don't add punctuation next to nr. as this negates search.
CHANGED YOUR EMAIL ADDRESS since registering?, click your username and check your address in User Control Panel, Profile, Account Settings.
If you want help to register, use "contact us" at page bottom for help.

Pre-selector gearbox over haul

Roark
Posts: 161
Joined: Sat Feb 13, 2016 10:52 am

Pre-selector gearbox over haul

Post by Roark »

The gearbox in my DE36 has done just under 68,000 miles and while the engine and gearbox are out of the car I thought I would have the gearbox checked over. Someone has suggested that a simple flushing out would suffice but as I was only able to travel about 3 miles before the brakes required attention I cannot be certain that the gearbox is working correctly.
Is this something that can be done by the reasonably competent or should I entrust this to someone else? Who would those who have such gearboxes suggest would be the best place please?

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

Re: Pre-selector gearbox over haul

Post by qantasqf1 »

The simple answer to this is don’t! These gearboxes are built like a (enter noun of choice) and the only parts vulnerable to wear are the brake bands; the only other parts that rely on friction are the top gear clutch plates, but they only transmit about one third of engine torque so they do nothing like the kind of work a conventional dry clutch must deal with and they last seemingly for ever. Sometimes the camshaft skew gears can wear after many miles, but if selection is OK then it’s no problem. Sometimes the brake band self adjusters get a bit sticky, but if you’re careful these can be freed up pretty simply. As a precaution I agree a good flushing and fresh oil (SAE30) is a good practice. Besides all this a preselector with 68000 miles is a young shaver and should have years left on it. As long as it’s behaving itself I’d definitely leave it alone.
Last edited by qantasqf1 on Wed Sep 12, 2018 7:14 am, edited 4 times in total.

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

Re: Pre-selector gearbox over haul

Post by qantasqf1 »

I'm so determined to get this incredibly concise, articulate and thoroughly well researched article I have published it a second time just in case readers - if any - have missed a vital point in the first.


The simple answer to this is don’t! These gearboxes are built like a (enter noun of choice) and the only parts vulnerable to wear are the brake bands; the only other parts that rely on friction are the top gear clutch plates, but they only transmit about one third of engine torque so they do nothing like the kind of work a conventional dry clutch must deal with and they last seemingly for ever. Sometimes the camshaft skew gears can wear after many miles, but if selection is OK then it’s no problem. Sometimes the brake band self adjusters get a bit sticky, but if you’re careful these can be freed up pretty simply. As a precaution I agree a good flushing and fresh oil (SAE30) is a good practice. Besides all this a preselector with 68000 miles is a young shaver and should have years left on it. As long as it’s behaving itself I’d definitely leave it alone.
[/quote]
Last edited by qantasqf1 on Wed Sep 12, 2018 7:52 am, edited 3 times in total.

grahamemmett
Chief Geek
Chief Geek
Posts: 1361
Joined: Mon Feb 08, 2016 8:12 pm
Location: Northwich, Cheshire
Contact:

Re: Pre-selector gearbox over haul

Post by grahamemmett »

I agree with Steve. It ain’t broke..
I inadvertently started a debate on here last year as somebody said the manual says to use paraffin to flush the gearbox when changing the oil. And so it does. I said we must have moved on and I’d use flushing oil but the opinion was this would leave a residue and be detrimental to the new oil. In the end I just drained the gearbox and refilled with fresh SAE 30. The oil I drained out looked like it had been put in the day before.

The full manufacturers manual is available for download on www.DB18.org along with some detailed (and hilarious) technical articles about the gearbox and it’s adjustment from Steve Moore who responded above.
Graham Emmett ¦ DLOC Chairman ¦ chair@dloc.co.uk ¦ 07967 109160
Northwich, Cheshire
DB18 1949 LCV522 (Yes that one with the P100s)

Roark
Posts: 161
Joined: Sat Feb 13, 2016 10:52 am

Re: Pre-selector gearbox over haul

Post by Roark »

Thank you gentlemen. One less task for me then. All I have to do is clean off the covering of oil and dirt before replacing the tail shaft oil seal.

terryfrombury
Posts: 154
Joined: Fri Feb 12, 2016 10:25 pm
Location: Cheshire, UK

Re: Pre-selector gearbox over haul

Post by terryfrombury »

Someone who knows a lot about pre-selector boxes, and has rebuilt quite a few told me that if you dipped your finger in the oil and it did not smell of brake linings, then all that was necessary was to ensure that the adjustments were right. The thing that apparently can get a bit stuck is the automatic adjustment system that is supposed to take up slack when the change gear pedal is depressed. If the slack isn`t taken up on any of the gears then you can end up with a false neutral.

Roark
Posts: 161
Joined: Sat Feb 13, 2016 10:52 am

Re: Pre-selector gearbox over haul

Post by Roark »

Thank you for the information.

I asked Graham Whitehouse for a price and apparently it's £4500 plus VAT which includes bearings, linings and the rear oil seal conversion.

JT7196
Extremely Wise Man
Extremely Wise Man
Posts: 1535
Joined: Sat Feb 13, 2016 7:22 am

Re: Pre-selector gearbox over haul

Post by JT7196 »

Yes I too had Graham overhaul my LA11 Gearbox a few years ago, including the rear Oil Seal coversion, plus some other work that needed doing.
Cost at that time was circa £3000, but it has behaved immpecably since, so well worth the mon ey I my opinion.

Cheers Al

terryfrombury
Posts: 154
Joined: Fri Feb 12, 2016 10:25 pm
Location: Cheshire, UK

Re: Pre-selector gearbox over haul

Post by terryfrombury »

From what I have heard, you need to be quite careful about handing the box over to a professional rebuilder. Apparently with one or two there is a tendency to charge for a complete rebuild even if only one part needs sorting.

Noelex
Posts: 40
Joined: Wed Jul 13, 2016 11:27 am

Re: Pre-selector gearbox over haul

Post by Noelex »

As part of the restoration process of my Special Sports considerable work has been completed. The bronze bushes between the gears do wear out. An overdrive exacerbates this. The bearings wears as do seals the oil pump and bands. A full rebuild is not for the faint hearted. However if you can take off the inspection cover easily and this will provide some indication. Are the clearances between the drums okay. Use feeler guage. Is oil clean and smells okay. Is it pretty silent don't worry about reverse. If it's changing okay just change oil. There are some good books available. And how far do you intend to drive it? My car clearly had been driven at speed. It had got very hot some gears had been blued from heat generated!. The bushes were utterly worn out. The front shaft can be twisted. Cheers
Hugh Spencer

Post Reply