Colin Lindsay Posted August 13, 2022 Report Share Posted August 13, 2022 I've had an unusual sensation with the Herald ever since it went back on the road; move off in 1st, select 2nd and on engaging the clutch, the car jumps forward as if overdrive is coming on. The overdrive worked originally but now no longer seems to work regardless of the column switch and the solenoid doesn't click. I thought it was stuck OFF but it might actually be stuck on. Today it was unmistakeable - overdrive is coming on once 2nd gear is selected and we hit certain revs. Thoughts, guys? It's NOT electrical as I've disconnected the circuit but in any case there is the usual 3rd and 4th gear inhibitor switch on the top of the box, which cannot come on in 2nd otherwise it would come in with 1st as well. I can only think that the solenoid is stuck in the 'on' position, and - does this sound logical - overdrive is coming in once the car reaches sufficient speed to pump oil round the O/D unit in the necessary quantity? This is why it doesn't come on in 1st, nor does there seem to be any problem with reverse. Three or four times today at around 50 mph, the revs in 4th were too low and I had to change down to 3rd again; this has now made me think that the overdrive was on regardless of the column switch position, and it starts to make sense. I stripped the solenoid down and cleaned it, before fitting new o-rings and it was working well, but I reckon it's going to have to be a replacement that can be fitted and left alone. Any ideas as to why it's coming on even with the electrics disconnected? Link to comment Share on other sites More sharing options...
johny Posted August 13, 2022 Report Share Posted August 13, 2022 If your diagnosis is correct Colin could it also be engaged in reverse? Hopefully there wont be enough oil pressure to move the cone clutch to the OD position... Link to comment Share on other sites More sharing options...
Steve P Posted August 13, 2022 Report Share Posted August 13, 2022 Does it crunch when changing down, my Herald always does if you forget to take it out of overdrive?. Steve Link to comment Share on other sites More sharing options...
johny Posted August 13, 2022 Report Share Posted August 13, 2022 This thread should help Colin... Link to comment Share on other sites More sharing options...
Pete Lewis Posted August 13, 2022 Report Share Posted August 13, 2022 Jtypes dont wreck themselves in reverse its more dangerous in\a D type the solenoid valve is the only link to having a mind of its own as it can play up with no electrical associations i would take it off and give it a good talking too i hate suggesting you need to spend money ha !! Pete Link to comment Share on other sites More sharing options...
johny Posted August 13, 2022 Report Share Posted August 13, 2022 ahhh that would explain why it hasnt already happened😁 Link to comment Share on other sites More sharing options...
Pete Lewis Posted August 13, 2022 Report Share Posted August 13, 2022 i think its unwise to reverse but the one way cluch wont explode as can on a D type the J type has some survial built in Pete Link to comment Share on other sites More sharing options...
Colin Lindsay Posted August 13, 2022 Author Report Share Posted August 13, 2022 Very glad to hear reverse won't be an issue. I was prepared to do without O/D until the next winter stripdown, and deal with it then, but not if it causes damage. That thread in Johnny's link mentioned the O/D coming on as oil pressure builds up - might be my case. I rebuilt the solenoid, plus a spare, but the spare does not click nor rattle whilst off the car so it's on the shelf for future reference. The one I fitted worked first time and I was soooo happy, but it appears to have lasted less than ten miles on the open road. For some reason it appears the solenoid has engaged and is refusing to go off again. No crunching either, Steve, it's quite a good box - ex Spitfire plus J-type. I've noticed before how quiet it is, no noises at all, and it did on occasion jump out of third but that was when I had the larger wheel and so hit the gearlever with my leg. I also found that the speedometer is quite accurate - we passed one of those 'smiley face' speed indicators, the speedo was around 38, maybe 39 and it flashed up a speed of 36. I changed the USA-spec speedo drive gear for a UK version and it seems to be the right one. Link to comment Share on other sites More sharing options...
johny Posted August 13, 2022 Report Share Posted August 13, 2022 Looking at the J type diagram to me the mechanical side looks very similar to the D type with a uni directional clutch which I cant see would be very happy being run in reverse as I think it would lock and try to cause the cone clutch to slip if its in the OD engaged position. Also the idea of engaging OD on oil pressure build up rather than solenoid operation could mean the cone clutch operates slower or intermittently thus accelerating the wear of its friction surfaces. Happy to be corrected on all this but otherwise I would want to rectify this problem sooner rather than later☹️ Link to comment Share on other sites More sharing options...
daverclasper Posted August 13, 2022 Report Share Posted August 13, 2022 1 hour ago, Colin Lindsay said: For some reason it appears the solenoid has engaged and is refusing to go off again. My J type was engaging and disengaging randomly ,(even with solonoid disconnected), would be after a while when driven from cold. Dave Twigger, O.D stuff, in Rugby advised probable issues with solonoid and maybe pressure relief valve, O rings. (PRV valve O rings, very fiddly job) Replaced O rings in both and was fine for about 8 years, car in regular use, though not high mileage. About a year a go had OD not disengaging after a bit of M way running. Went straight for solonoid. Not clicking when shaken. Cleaned out and replaced O rings (though seemed ok), whilst I was there. A bit above my head about how they work, just my personal experience. Oh, one other thing I read recently (not mentioned in my previous, extensive research, I don't think), there is apparently, a narrow oil channel/drilling?, in the righthand side of the solonoid housing, that can get easily get blocked with small bit of crud. Oh, Oh. I lubed the solonoid bottom piston thingy first time, though left dry this time, as I think the lube maybe got hot and dryed, out making it stick?. Who knows? Link to comment Share on other sites More sharing options...
Colin Lindsay Posted August 13, 2022 Author Report Share Posted August 13, 2022 55 minutes ago, daverclasper said: Oh, one other thing I read recently (not mentioned in my previous, extensive research, I don't think), there is apparently, a narrow oil channel/drilling?, in the righthand side of the solonoid housing, that can get easily get blocked with small bit of crud. Oh, Oh. I lubed the solonoid bottom piston thingy first time, though left dry this time, as I think the lube maybe got hot and dryed, out making it stick?. Who knows? Must look for that. I've just refurbished a spare solenoid but there was little or no movement of the piston. Stripped it down, cleaned it all up and found the body with a quantity of oil inside - I'm wondering if the oil was affecting the movement? I rebuilt dry, no oil at all. Anyway stripped down and cleaned, replaced the O rings etc and tested - loads of movement of the piston. This was without the end cap on. Replaced the end cap and spring, pushed it down, less movement but still clicking. NOW: replaced the circlip, almost no movement. Removed the circlip, the cap moved outwards slightly, now more movement. It seems the supplied circlips are too thick. Anyone know a source? They're not in any of the parts kits. Link to comment Share on other sites More sharing options...
Badwolf Posted August 13, 2022 Report Share Posted August 13, 2022 Should I have a type d or j on my three rail Spitfire box? If it could be either how do I tell which it is? Link to comment Share on other sites More sharing options...
johny Posted August 13, 2022 Report Share Posted August 13, 2022 I think a 1972 Spitfire might have a J type. Solenoid on right side = D type and left side = J type Link to comment Share on other sites More sharing options...
Clive Posted August 13, 2022 Report Share Posted August 13, 2022 34 minutes ago, Badwolf said: Should I have a type d or j on my three rail Spitfire box? If it could be either how do I tell which it is? Only the very last mkIV spitfires had the J type od. I expect teh commission number at changeover is out there somewhere.... Link to comment Share on other sites More sharing options...
daverclasper Posted August 14, 2022 Report Share Posted August 14, 2022 I bought a couple of circlips from Dave Twigger. If I still have the spare?, I can measure the thickness. If yours is too thick, could it be ground down?, though too fiddley Maybe? Link to comment Share on other sites More sharing options...
Colin Lindsay Posted August 14, 2022 Author Report Share Posted August 14, 2022 21 minutes ago, daverclasper said: I bought a couple of circlips from Dave Twigger. If I still have the spare?, I can measure the thickness. If yours is too thick, could it be ground down?, though too fiddley Maybe? Very fiddly, I find even the thick ones I have distort too easily. I'll try to source originals which are quite thin. I've e-mailed Dave although the link on his site isn't working. In the meantime it's a new solenoid, I can't take the chance of damaging the gearbox nor can I be bothered repeatedly taking the carpets out and the cover off, breaking all those lovely seals and disturbing everything, again and again. Link to comment Share on other sites More sharing options...
AlanT Posted August 14, 2022 Report Share Posted August 14, 2022 Worth driving with the tunnel out (carefully) to check working first! Link to comment Share on other sites More sharing options...
Colin Lindsay Posted August 14, 2022 Author Report Share Posted August 14, 2022 12 minutes ago, AlanT said: Worth driving with the tunnel out (carefully) to check working first! I did... last time, but it lasted maybe ten miles, two shortish trips, before giving up again. That was the original solenoid that came with the box, untouched. I'll replace asap. Link to comment Share on other sites More sharing options...
Pete Lewis Posted August 14, 2022 Report Share Posted August 14, 2022 13 hours ago, johny said: I think a 1972 Spitfire might have a J type. Solenoid on right side = D type and left side = J type had to read that twice Pete Link to comment Share on other sites More sharing options...
Colin Lindsay Posted August 24, 2022 Author Report Share Posted August 24, 2022 Well, we're hopefully cured. I called in last week with James Paddock and bought a new solenoid - no point in faffing about reconditioning solenoids only to have them fail very quickly. The old one on removal was stuck solidly in the 'open' position, not even a rattle nor any movement when tested. (strangely enough after an hour on the bench it suddenly started to rattle when shaken, but I wouldn't trust it further than I could rattle it.) This means that overdrive has been on all the time, but seemingly only triggering at certain revs, presumably on sufficient oil flow. I swapped the solenoid over, tested for the click, did my usual trick of replacing all the seals, soundproofing and carpet (remembered to refill the gearbox too) BEFORE roadtesting and then off for a ten mile drive this evening, during which the overdrive worked perfectly. In and out / on and off immediately in both third and fourth. No sign of any trauma caused by the sticking solenoid and even the gearbox itself is amazingly quiet. So: I hope that's us back on the road again. 1 Link to comment Share on other sites More sharing options...
Pete Lewis Posted August 25, 2022 Report Share Posted August 25, 2022 thats good , will you strip the sticky one and report ??? as for revs its prop shaft revs that drives the oil pump not the engine revs so back to smiley motoring Pete Link to comment Share on other sites More sharing options...
NonMember Posted August 25, 2022 Report Share Posted August 25, 2022 58 minutes ago, Pete Lewis said: as for revs its prop shaft revs that drives the oil pump not the engine revs At the risk of being accused of point scoring... technically it's the gearbox mainshaft revs rather than prop, but they're the same until the overdrive engages. Good news on the fix, Colin. Time to enjoy the car a bit instead of fixing it 😁 1 Link to comment Share on other sites More sharing options...
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