Having read the new Routemaster Manual to try and gain a better understanding of how these original gearboxes are configured and now being only slight none the wiser, I turn to the experienced folk here for assistance.

We have 3 Routemasters each with different configs/ issues which I'm trying to understand.

First is RML2649 which still has the ability to be fully automatic; intermittently. Secondly is RM1817 which works in semi-auto only, but has no control panel at all and RMC1496 which has a control panel but only works in semi-auto mode.

RML2649: We have resorted to mostly using this bus with the auto bypass plug installed (I know this is an emergency measure) which is why I need to resolve the issue. It mostly works fine in full auto, but intermittently, mostly in wet or cold conditions, it will give serious issues. When changing up a gear it will immediately decelerate and struggle to move, as if someone has yanked on the handbrake. I've always thought/ felt that it's engaging at least 2 gears at once, if this is even possible. Not sure if the control panel is faulty or the loom has an issue, but it works perfectly in semi-auto mode (expect that you can engage 1st or 2nd gear at 40mph if you wanted) which leads me to believe that its an issue with a signal rather than a component? Any ideas of where to start investigating this issue?

RM1871: This bus only works in semi-auto. I wanted to investigate putting the bus back the full auto mode (we have our reasons) and to my surprise the control panel behind the drivers head was non existent. Also no sign of any wiring at all. I assume that someone has performed a serious re-wire, but having read the manual I would image that would mean no control measures in place. Any ideas what’s happened here?

RMC1496: I’m of the understanding that the RMC was configured from factory to only work in semi-auto mode and would have had a medium speed differential. However our bus has the normal differential only achieving top speed of 40mph. This setup appears to work fine with the exception of changing from 2nd to 3rd requiring closely matched engine/ road speeds to order to happen, which is unlike the rest of our fleet. My query about this bus, is it possible to instate full auto mode?

Kind regards
Barry

My bus number (if any): 2469, 1871, 1496

First with the RML, presumably it is a refurb with Cummins/Iveco/DAF engine? they are prone to 2 gear selection. the gear selector switches positive to the control panel; the control panel switches negative to the EP block. The fault is usually a combination of things, the most common being the body is wired negative earth. the body should be neutral. What happens is the 7 core cable from the panel to the eP block wears where it leaves the conduit and enter the EP block. A bare wire will chafe on the body, giving a false negative feed to the EP block. As the return is positive, you get whatever gear you select plus the one with the wire touching. By inserting the by-pass plug you make the EP block back to positive switching. the fault goes away. You'll probably need a replacement gearbox in the near future as the bands ill be worn out.

I must have done a dozen or more buses in the last few years at home and abroad with the same problems. Also check out the wiring, the plug you put in for the satnav, earthed to the body, the radio, earthed to the body. All will cause problems.

The next RM, I'd suggest keeping it as it is unless you can source the correct control panel and associated plugs and you have a speed sensor somewhere in the drive line. What engine does it have, that makes a difference.

The RMCs were factory built with control panel but wired for manual operation. they did have an auto netral position when built which required the control panel. It's complicated and I haven't got time to explain it here. I do have the original wiring diagrams for the RMC, table top size, 12 sheets of them, so please don't ask for a copy! It may be that your bus has had 2 gear selection or maybe one gear is slow releasing.

My bus number (if any): RML2532

Hi Roy, thanks for your quick reply. I should have stated engines. The RML is a Cummins C, the others are both AEC engines. I agree that the RM is best left alone, just wondered what had been so to keep it working without a control panel. The info provided for the RML issue sounds promising.
Thanks
Barry

My bus number (if any): RMs737, 875 & 1353 (driver)

I think you are going to be in trouble trying to restore automatic to an AEC RM if the speed sensitive generator is missing.

that ought to be possible using a later control box form a Cummins refurb if you can find one, then use a tacho sender on the rear prop flange to provide the signal. But I doubt there's been many if any refurbs that have been scrapped. A control box rebuild can cost up to £250 if you can find anyone to do it.

You're looking at a lot of money and work to little end benefit.

Just thought you'd need to source the NATO connectors too! Maybe try a scrap DMS?

My bus number (if any): RML2532

I think the option of rebuilding a control system for the RM is too much for the reward. I has thought that the RMC might be an easy mod, however If I understand correctly I would need someone who understood and had access to the wiring setup for the RMC to be able to convert that to full auto setup. I thought that might just be a case of some setting within the control panel. At least now I have a clue to repairing the RML which is my main priority.

My bus number (if any): 2469, 1871, 1496

If you are unsure, depending on where you are located, either myself or roy could probably help resolve your problems.

I'm based near Ashford, Kent but do mobile work as well.

My bus number (if any): RML2532