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DB18 Gear Selection Problem

Posted: Thu May 30, 2019 5:32 pm
by Hedgie
Hi All,
I have finally got my Daimler DB18 DHC on the road and am de-snagging it. We took it for a 150mile run and found the following probems with Gear Selection on the Pre-selector Box:-

1. Most of the time, but not all the time, it was NOT possible to change UP from 3rd Gear to Top Gear. On the times that it failed it stayed in 3rd.
2. Almost all of the time it WAS possible to change UP from 2nd Gear to Top Gear.
3. It was always possible to change UP from 2nd Gear to 3rd Gear, and from 1st Gear to 2nd Gear.
4. It was always possible to change down from any Gear to any other Gear.
5. It was always possible to select Reverse, 1st and 2nd Gears.
6. It was always possible to select any Gear, including Top Gear, from Neutral.
7. Once any Gear, including Top Gear, had been selected successfully, the car ran without problems in that Gear.
8. On several occasions false neutrals were selected with the pedal quickly coming up.

Does anyone have any suggestions as to whether the failure to select Top from 3rd Gear might be a Gearbox problem or a problem with the linkages not being set up correctly?

Can anyone recommend an expert repairer of DB18 Gearboxes?
DSC00733 (Low Resolution).jpg

Re: DB18 Gear Selection Problem

Posted: Thu May 30, 2019 6:55 pm
by Rolf B.
Hello Hedgie,

I recommend to get in contact with G. Whitehouse Autos Ltd.
www.gwautos.com
info@gwautos.com
Tel.: 0121 559 9800

Best regards to the very lovely twin villages Streatley and Goring from Mannheim, Germany
Rolf B.

Re: DB18 Gear Selection Problem

Posted: Thu May 30, 2019 10:16 pm
by Mark Bullen
I have a similar problem that reoccurrs intermittently. It's fixed by moving the carpet and/or rubber boot underneath the gear change pedal.
I have just removed the floor boards and have a replacement rubber boot on its way so hopefully that will cure it. Hopefully this might work for you.

Re: DB18 Gear Selection Problem

Posted: Thu May 30, 2019 11:27 pm
by grahamemmett
Hello Hedgie
Sounds like a linkage adjustment issue. It’s so darn finicky.
I have Kevin Bennett’s recommended method somewhere which works well and I’ll post it.

Mark - where did you find the gaiters as I desperately need some!

Re: DB18 Gear Selection Problem

Posted: Thu May 30, 2019 11:55 pm
by Eric990j
My LD 10 did similar things and it was slight play in one of the linkages. Had me scratching my head for ages and needed a friend with an eagle eye to spot it as it was very slight. We fixed it and I was so surprised, it’s perfect now. I wasted so much time before adjusting the linkages which never fixed the issue, just moved the problem or created new issues !

Re: DB18 Gear Selection Problem

Posted: Fri May 31, 2019 10:11 am
by Simon Hyslop
The adjustment required on these can be very very small but another source of this type of problem can be wear in the small ball joints in the linkage. You really need two people, one in the car at the lever and the other at the quadrant on the gearbox. The person underneath needs to look at the quadrant being moved from 3rd to top. Can you now move the quadrant further in the same direction (maybe 1 1/16 of an inch , or an 1/8") until it stops? If so, it is now probably in top and by looking and feeling each joint in turn you will find where the trouble lies.

Any slop in the linkage will prevent it moving fully to where it should be and this needs to be either adjusted out using the screwed rods at the joints or by replacing any joints (Vintage Supplies have them all) which allow back and forward motion in the joints without actually transferring motion from the lever to the quadrant. Once sorted, it should work perfectly. Sort top and and the rest should be in the right place too.

Re: DB18 Gear Selection Problem

Posted: Fri May 31, 2019 6:50 pm
by Mark Bullen
Hi Graham, I found them on eBay through landcruiser102. They've just arrived and not the best moulding for surface finish, but should keep me occupied. Thanks Mark

Re: DB18 Gear Selection Problem

Posted: Sat Jun 01, 2019 12:43 pm
by Stan Thomas
Your problem may be one of two things - or both - but it is very unlikely the gearbox requires attention if it is possible to get all gears, even with some difficulty. So here goes:

Most likely, it is the linkage , given you can get top gear from 2nd when the movement of the linkage as such provides sufficient momentum to move the change-mechanism to select top. So simply extend the linkage one half or one full turn at the ball joint and try that. no need to road test as the gear-change pedal invariable settles at different heights for each gear selected.

Secondly, is the gear-change pedal travel sufficient (as in a previous post - is there any carpeting or mat restricting travel)?

Having checked that, you need to get under the car and detatch the pull rod to the gearbox and shorten it a little (I assume the same set-up as the Conquest models for which I have the manuals). Effectively, unless the gear-change pedal causes sufficient movement in the gearbox (it actually depresses the bus-bar to allow the "old" gear selection struts to unload and the "new" gear being selected to advance on to the bus-bar).

When some wear has occurred in the gear change linkage, the problem you describe will occur.

Let us know how you get on via the Forum - or I'll talk you through it if you PM me.

Stan Thomas.

P.S.
About 50 years ago I went on a breakdown for exactly the problem you have! It turned out to be Mary Whitehouse's car (of "clean-up" TV fame) - so it was a good job I didn't F and Blind while I did the job.

Re: DB18 Gear Selection Problem

Posted: Fri Jul 12, 2019 5:22 pm
by Hedgie
Many thanks for all your suggestions as to how to fix this problem.

It is now fixed and I am able to engage all gears going up and down from Neural to Top.

It did indeed, as you all suggested, turn out to be a linkage problem and on the 3rd attempt we have the promblem solved, by suitable small adjustments to the gear selector linkages.

If anyone has a similar problem, I suggest looking at the replies to this topic.

We now have another problem with Reverse Gear, but I'll post a new topic on that.