Tipidave

Thanks again... Yes it has the angle drive and yes it has the washer fitted... I think I will remove the speedo and 'fettle' with it out of the dash.

Thanks Pete. Do you happen to know (or know where I can find details of) what length of inner cable is needed to engage properly and what maximum length can be so as to avoid Interference.

Hi all , My speedometer failed soon after the installation of a d type overdrive to my 1967 Herald convertible. The speedo was professionally overhauled about a year ago and had been working fine before the overdrive installation. First symptom after just a couple of miles was that the speedo needle refused to settle below 20 mph. Then the speedo stopped working altogether. I released the cable at the speedo end and the needle dropped back to zero whereupon I reinserted the cable and tried again... the speedo didn't register any speed, although the odometer is registering. I have since installed a new cable (having been advised that the original had too much core showing). The Speedo now only works if the cable is backed off a bit and now (with it backed off)... I have a situation where the Odometer reads correctly but the speedometer (albeit steady) over reads by approx 10 mph up to 35 mph and then 15-20 mph between 40 and 55 (as measured against a phone based gps app). The fact that the odometer is plumb bob on would indicate the correct TPM and that the cable is turning correctly? I am a bit confused... Might I have damaged something inside the speedo head? I would be interested in your collective views/ experience in respect of diagnosis and possible prescription to fix..

Thanks for all of the replies. I have thoroughly inspected and measured today and all is well no play at all. No means of adding grease to one of the uj’s so guessing it is a sealed for life bearing. splines all good and no sign of wear or play. accurate measurement is 47” which is correct. However this is the measurement with the slider at shortest length. Still a bit concerned about how to deal with the length if indeed it is 46 1/2 “ that is needed.

I will have a fiddle tomorrow 👍thanks for the suggestions

I have test to fiddle with the adjustment and have not inspected the splines. Overall the condition seems better than I was expecting.

Hi again all, Just to recap…plan is to fit a three rail spitfire box with d type overdrive. I recently tried to purchase a new propshaft (vitesse non overdrive 47”) that stated it was good for herald overdrive conversion but vendor had just sold out. He said that he had a secondhand one available so I Purchased that. It has arrived and measures 48 1/2” with what looks like about max 1 1/4 “ of adjustment in it to shorten. Is it normal to measure from flange to flange? Or some other way. Have I purchased a dud? My understanding is that length needed is 46 1/2”. I am trying to assemble everything I need in advance and now a bit unsure. thanks david

Thanks for the info. It was sold as a working concern so I think I will fit a new end seal on the overdrive and a couple of new gaskets and fill up with oil. 👍👍😀

I am making progress with my three rail d type overdrive that will go into my Herald 1200. I have drained out the old oil and it looked reasonably clean with no nasties in it. The magnetic sump plug had scavenged just a very few bits of fine metal adhering to the magnet. I have removed the overdrive filter and cleaned both it and the magnetic rings. It did have small amount of grey sludge no sign of black clutch material so I am guessing not significant and nothing untoward. so… my question is do I need to flush both through with either duck oil or paraffin or similar? To be belt and braces, Or just refill with EP90 when the time comes?

Yes the wire comes out 10cm from the collar that the gear knob attached to. 😀

Would someone care to check my thinking… diagnosis… the gear stick provided with the box is not correct. It has a spring mechanism to lift to reverse rather than press. And should not be part of this set up. prescription… I am thinking that I should be able to take the gear lever (only) from my original herald three synchro box gearbox and substitute it for the wrong ‘un. Is my diagnosis right? will prescription work? I am not interested in having the overdrive switch on the gear lever and plan to use a column mount switch. ince again thanks for help so far 😀👍

Also, is this metal ring correct on the middle rail?

Is there any easy way to identify? that spoils my next plan which was to make use of my existing 1200 gearbox top cover. Maybe this is what has been done there … the current gear stick definitely isn’t right.

Thanks for the suggestions… something not quite right! Unfortunately I have to work! Would rather be at home fettling 😀👍

Also, is this metal ring correct on the middle rail?

Thanks for the info… with the gearstick removed I can move the third rail and engage reverse in position as described. However with the gear stick on I cannot move the lever far enough to the left. Does this mean I must adjust the lever that acts on the gear selection rails via the shift rod?

Ah… the schematic in the gear knob ( with overdrive switch) shows it left of second!) doh

Hi All I now have a three rail spitfire gearbox stamped with FH number and a d type overdrive that I want to fit to my 1200 herald. The unit has been stood for many years. The solenoid plunger was sticking and found to be lightly corroded. It is now free and clean and operating with a 1.1amp maintaining current. With the inspection cover off the hole in the brass lever exactly aligns with the driled hole in the casing when energised but when released the lever moves back to the right but not as far as it could do. Is this because there is no oil pressure while testing on the bench? Is there any other adjustment? As a secondary issue, I am happy that all forward gears engaging smoothly with no undue play or noise… but for the life of me I cannot engage reverse. Is there a knack or adjustment? It looks like it should be a lift and movement to left of second gear. Any help as ever greatfully received. 😀👍

I may have sourced a suitable candidate box to start the conversion process… can anyone help to diagnose the following numbers that are stamped on the candidate… -FC 67790 this is stamped, the following are in the casting--303546---N295---303709R, thanks in anticipation david

Is there any reason that I should not use a spitfire 1500 gearbox with j type overdrive. I think it has the switch gear in the gear knob. Thanks David

As a bit of an aside… I have now received my October copy of the Courier and have read Colin’s most excellent article on installing an overdrive … I do like these little synchronicities in life. Just as I start to ponder a way forward… within a week a most useful article plops through my letterbox. So… thanks for that 👍👍👍😀😀

Thanks for all of the answers. I think that I will try to piece together all of the components… I am not in a rush. 👍

I have read various threads in the topic of converting a std 1200 herald to an overdrive and I find myself somewhat bemused by all of the options and potential pitfalls. Can anyone describe what would be the best overdrive to look for and talk me through the steps needed to convert?

Thanks for the prompt replies… one slightly alarming aspect to the drop back to zero is the ‘loose and floppy’ fall back. Did wonder if a return spring had failed. It will have to wait a week or two as I am away but I will then proceed with caution as advised 😀😀👍👍🧐

All has been well with the herald save for a sudden onset change to the operation of the Speedo. It seems to rise correctly but then does not drop back unless tapped on the glass with some force. So in effect is is just recording maximum speed achieved. Now, being a 1200 speeding is never really going to be an issue… but I have no idea where to start… new cable about 18months ago. Not used much over winter but out and about for around 400miles so far this year. Sudden onset. Any ideas????