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Morning all, I suspect a quick question, is it possible to remove the overdrive without taking the the gearbox out? Appreciate gearbox will need to be supported, but is there enough room given the length of gearbox mainshaft. Thanks

Hi all, I’m hoping someone can help me work out the strange issue I have with the J Type overdrive on my CR series TR6. it only seems to work the first time I operate the switch, no matter how long the journey! It has for a long time been a little intermittent, usually to do with the oil level, but works again when topped up. when I was doing some work on the car recently, I made sure it was up to the fill level (plug on the side of gearbox), possibly a few ml extra. it seems to be after that that it first started this issue. electrically seems ok, I’m getting over 13v at the solenoid.… .. but it has me puzzled! thanks in advance! Richard

A noise and vibration are developing from the gearbox and overdrive, when I engage OD, the noise and vibration almost disappear. It is more noticeable in higher gears. Any idea wherle to start looking, gearbox or od?

Dear Collective As you may recall, I recently removed 3 teeth from the 1st gear portion of my layshaft. I have since obtained the necessary parts to repair the box, including the broken 2nd gear bush that I have found after stripping. The other night, I also bought an interesting overdrive box from a Standard Vanguard / Triumph enthusiast which I hoped to fit to the car so I could take my time rebuilding the original box. It cost less than the spare cogs cost me, so I couldn't resist. We tested the box using a TR4 lump mounted on a test rig, and everything worked as it should (gear selection, overdrive operation, overdrive oil pressure, etc). However, I have a few queries relating to the box / overdrive combination, mainly concerning compatibility with my 3A. These are listed below, including one minor issue that I have already solved. I have also inserted some photos to illustrate. 1. Clutch actuating lever: the Standard Vanguard item is a two hole lever, with different angle to the TR item. Easily swapped so no issue. 2. Gearbox ID number: the ID number on the box starts with VF. According to both my sources of Info (How to Restore + Moss Catalogue), VF boxes should be 4 synchro, but this box is most definitely 3 synchro, with the casing an identical match to my original TS stamped box. Anyone care to explain this? Either the books are wrong, or someone messed with the serial number? 3. The overdrive unit, as I have since discovered, is an original Standard Vanguard item, which means that it has the serial number 28 / 1327. This of course means that it is a 28% overdrive unit, rather than the TR standard 22% It is an A-Type overdrive, identical externally to the 3A overdrive which has serial number 22/1374. Is there any issue with using this higher ratio of overdrive? I think this will result in 3rd overdrive being lower revs than 4th, but I actually quite like the prospect of having the car geared slightly higher for more relaxed high speed cruising. 4. I need to swap the solenoid mounting plates: the Standard Vanguard solenoid is mounted horizontally, whereas the TR is vertical. Swapping the plates would appear to be straightforward, but there are some interesting differences, e.g. the o-ring which seals the operating shaft is on the inside of the TR plate, but the outside of the Standard Vanguard plate. The one difference that I am most interested in, though, relates to the accumulator spring behind the plate, and the backside of the plate where it presses on the spring. On my 3A overdrive, there are two springs, exactly as expected. The Standard Vanguard has only one spring, which is fitted inside a solid brass tube, perhaps similar to the spacer tube used on later 4A overdrives with softer engagement? In addition to the differences in the springs, the plates are also different in that the Standard Vanguard item has a small protrusion which inserts inside the accumulator spring to hold it in position, whereas the TR plate has a hole in the same location, so no spring locating protrusion. The question is, can I safely use the TR plate given it does not have the spring guide? 5. Finally - the Vangaurd box has splodges of alloy where the 3A box has what looks like nice neat little ball bearings in the casing. I don't know what these are. Are both factory, or has one been tampered with? Hoping one of you out there is an expert on Vanguard overdrive boxes! TIA Malcolm Glover

Hello guys, I'm playing with a Tr6 gearbox, to convert it to overdrive, using a saloon donor box, as many of you have done previously. My problem is : the mainshaft diameter, where it get in the input shaft needle roller bearing is smaller than the "non overdrive" mainshaft (who's .875" apparently). Is there a sort of sleeve to fit in between ? I was thinking of 145008X, but the one I get from a supplier is far to big Thanks in advance for your help,

Really basic question but could somebody tell me whether flicking the overdrive stalk up on a TR5/6 should engage or release the overdrive. Many thanks Tim

Hi, could I get some thoughts on the attached TR2 dash photo please. There are holes in the metal dash (under my A & B stickers) and the holes have been trimmed over. I want to fit an overdrive switch with a separate neon indicator fairly soon, but leaving a thought for a heater switch at some point in the future. Bill P's books show a variety of combinations and layouts in this area of the dash and I was looking for some standard positions to follow. Many Thanks Bob

Hi guys and gals My overdrive investigation continues. The new solenoid has certainly helped with the blowing of fuses, but I can't help but feel that there is something with this 2nd hand o/d that is the root cause of the solenoid problems. Even on today's test drive, on a couple of occasions the solenoid twitched as if it was trying to pull in, but did not actually lift the lever. Fortunately I was being very careful to monitor this and turned off the overdrive within a second or so. 99% of the times I flicked the switch, though, the o/d engaged as it should. What I have noticed is that the actuating mechanism on the overdrive is very much stiffer than the mechanism on the original overdrive that is now out of the car. The original overdrive actuating mechanism is comparatively light to the touch, while still returning to the off position in a positive manner. The o/d box that is now in the car is very much more stiff to operate, requiring much more pressure on the lever when engaging manually. I have removed the valve and spring / plunger / ball etc and notice that the spring is very, very stiff. It is 11/16" in length. I have been unable to remove the same items from the original box, because the top bolt is so tight I think I need to get an impact wrench on it (something I am yet to acquire). However, I am almost certain that the spring in the original o/d must be significantly less stiff, otherwise the operation would not be so light. I have compared the spring with the springs found in the synchro hubs: the synchro hub springs are shorter and thicker wire, but I would estimate the compressive effort is similar between the two. Can anyone comment? Below is a photo of the spring with other components. It looks heavier than the spring shown in a o/d guide I downloaded from the interweb (also inserted below), but that could be a trick of the photo. My spring etc: Spring shown on Green County Triumphs guide to overdrives: Thanks!

Hi I'm doing the clutch on the TR6, I have a leak coming from the rear of the Overdrive where the prop shaft flange goes in to the Unit Can I remove the nut and take the Flange off and just replace the seal or is there a pre load on this nut. Also if not and I can does anyone know the Torque setting? Thanks

Hi All Well this started a number of months ago when my overdrive started dropping out randomly when in 4th OD. I was sure it was an electrical issue as it could work fine for hours of driving. It appeared to be worse when hot and tended to happen when the revs dropped while still in fourth. I checked all the electric and couldn’t fine a problem and as we were about to head off to Spain and France with the car I decided to leave it alone. We covered 2380 miles, 3 Tr6s with no problems, however my overdrive continued misbehaving, a little worse in the hot weather. However we arrived back in Portsmouth and drove straight home, 505 miles and it performed perfectly. I have a number of jobs to do on the car this winter; including recovering the central dash support, so I decided to remove the gearbox cover to try and sort out this problem. I checked the electrics and everything works correctly, so I fitted my pressure gauge and disconnected the propshaft. At tick over in neutral the pressure is 100psi In 4th gear at 2500 to 3000rpm the pressure is 450psi engage Overdrive it drops momentarily to 200psi then back to 450psi disengage OD and the pressure doesn’t move. So far so good. However once I reduce the revs the pressure immediately drops to 100psi and if I then turn off the engine it drops to zero within a minute. So my question is, am I correct in thinking the pressure should be maintained, and if so what could be causing it to drop. Thanks Cameron

Hi all, This might seem a strange set of questions but I'm trying to understand how to operate overdrive as I've never driven with this before, and I'm hoping to have my car back soon- it really has been the slowest and most stalled of rebuilds ever known!! I know o/d can be used in 3rd and 4th on mine. 1. When should I operate o/d for the first time on a journey - do I have to be at a certain speed and in 4th at first selection? 2. Do I need to deselect o/d before shifting down from 4th to 3rd? 3. Do I need to deselect o/d before shitfting up from 3rd to 4th? 4. When I turn the engine off is o/d cancelled if I haven't already done it? ie will it still be in o/d when I next turn the car on? 5. Is there an easy way to know if o/d is selected whilst driving (other than the revs being lower)? Thanks, Steve

Well, new to me anyway... I've been making do with a crescent shaped spanner for my overdrive sump drain plug, getting grazed knuckles in the process, but I recently found out Moss now do a proper ring spanner (part number 521814T) - hopefully makes life that bit easier! Comparison photo attached. Cheers Steve

The Solenoid mount side plate of my overdrive still leaks, even after ensuring the plate was flat, fitting a new gasket and smothering both sides with Hylomar Thicker gasket, silicon sealing compound .....? Anyone faced this and solved the problem with a 'cunning plan' all ideas gratefully received

So I have a new OD solenoid which I was going to fit today, as the garage had a look and said all seemed fine with what was going to it but it was not operating. the wire was disconnected and up on top of the box (I assume the garage had left it off), so had to get the tunnel out to get at it....which was a pain! Reconnected wire to old solenoid, sure enough, a click is only heard from relay when disengaging, nothing from solenoid and no operation. Connected new solenoid (did not install it in situ).....same thing. Put meter on cable to solenoid....sure enough 12.5 ish volts on it when engaged, 0 when disengaged. Put meter on old solenoid, disconnected.....very low ohms, going up to 12 ish when plunger pushed up. Same on the new one. This indicates they both should work fine, right? But no dice.....I can't figure what the problem is.

Hi i own a CP version UK 1971 TR6 with overdrive, have done since 1979.The car was professionally rebuilt in 1993 and at the same time the gear box was rebuilt by Pete Cox. The car has done only a few thousand miles in the last 25 years. However it does have a problem time to time with gear selection when going into reverse. Twice I’ve knocked it too far over and got it stuck. The first time the gear box had to come out. It’s time this got sorted so can anyone recommend a TR specialist who can replace the worn gear selection mechanism and attend to any other gear box issues they may find along the way? I live in Hampshire.Thanks in anticipation of recommendations.

I realized today that the headlights in my '63 TR4 stopped working. And the overdrive also stopped working. I'm very new to this car and not familiar with the electrical system. Thinking things through, I did just finish working on two things related to my electrics: 1.) I just added a battery charger cable/lead to the battery. In doing so, I did touch the wrench to a ground by mistake, creating a spark. 2.) I relocated my dip switch (up higher) to create a dead pedal spot for my left foot . Both fuses appear OK. And reading a few forum entries here on Triumph Experience, I understand the TR4 headlights are not fused. So what should I check?? Thanks in advance.

Had problems with the Overdrive that turned out to be the switch. So I replaced it, but this one is nearly as bad in as much as the overdrive will keep dropping out and reengaging. Are they all from the same source or are some better than others? Definitely the switch because if I put pressure on it I can get The overdrive to cycle! Or has anyone managed a good modification?

Hi All Kind of linked to my previous Overdrive post (Electricy Help) but more help needed with my electrical bits. So for info it’s a UK 72 Pi and I’m installing ALL new Autosparks harnesses for the model and options. So the Autosparks mini harness code 865 goes from the relay and ends up with two spurs, one goes to the OD and connects via another little harness BC58, and hopefully I’ve got that bit ok now. But there is still that question where does the second spur off the 865 Relay to OD harness go. It has to go to the OD switch right? But harness has a yellow green wire and a plain yellow, but the switch has the same yellow green but a black. Hmm. I suppose the black earth from switch can connect to any earth but not sure about the single yellow from the OD harness (865)? Then there is a spur off the main harness, kind of after the heater and behind the Tacho. It contains 4 wires, 3 brown of varying thicknesses and a white with a red trace. So not sure what it is or where it goes. I was thinking through the bulkhead to supply the starter but not sure. Slightly daft question, apart from the Horn wiring do all three column switches go under the steering column harness cover (part 611369) I’m assuming they do but it seems a bit tight through the alloy column clamps (611529 and 611530). Hopefully pics below will help. Cheers Keith

Anybody need a Gbox with a jtype and a 6cyl? Would all need re-doing

First time using the Forum today although I confess to being an avid follower and have benefitted from some great advice and tips. I have a Type A Overdrive in my 1970 TR6 which engages straightaway when switched on however it has recently begun to disengage under acceleration? Almost like having a kick-down in an auto transmission vehicle! It quickly re-engages when the throttle is backed off and will cruise happily until an incline is encountered or any additional power is applied. Oil level was fine when last checked prior to being put away for the winter, although that was a little while ago, the car hasn’t been out much (once this year!) Suggestions greatly appreciated…

Hi All Bit of a query with fitting my new(ish) overdrive harness. Now the wiring diagram for the overdrive is pretty simple. But the reality looks a little more complex to me. My A type has three switches mounted on the GB top cover, presumably the various on/off switches to stop engagement at the incorrect times, ie reverse and 1st. So I need to install my Autosparks 863 overdive harness, pictured, and 865 overdrive relay harness. The relay end of the relay harness is simple enough but I’m not sure about the gearbox end. Does anyone have any pic s or diagram of which colour wires go to which switch and in what order and I’m assuming the feeds from the relay go to one of the switches (first one) on the gearbox but not sure and need a little guidance. Thanks Keith

I think I may have finally got to the bottom of why my overdrive was taking an age to disengage. The restrictor valve was blocked. To get to it, I had to dismantle the interior of the car to get the gearbox tunnel out. Was there an easier way to get to the pesky thing? Have I just done something the hard way? Pictures attached of the valve (With a pin in it) and the stripped down TR4A interior. Best. Paul.

I have to replace the wiring for the overdrive on my j type overdrive on my TR 6 C.R as it currently resembles a burnt out sparkler ! A previous owner has used a relay in the circuit which I dont think it should have. It has also been modified to work on three gears. What ampage wire should I be using for the circuit to operate the overdrive ? Should I use a relay in the circuit? MARK

Hello (again) All I have a choice between putting in a J-Type or A-Type overdrive in my restoration project. I was just wondering what peoples thoughts on are this are. I know the A-Type is the correct OD, but is the J-Type a better unit to have? I will keep both units with the car so the next owner (if I ever do sell it!) can change it if they so wish. I have heard that the J-type is the better one to have in your car and use; the A-type can be slower to engage/disengage as well as being more tempremental. Of course, the J-type will give a higher drop in RPM, but I'm guessing going from 22% to 28% doesn't make too big a difference. Any help would be greatly appriciated as I feel I'm in the middle quite a dilemmia. Thanks in advance!

Hi All With a lot of help from a fellow club member,we removed the gearbox from my 1971 Tr 6 today. The reason for removing the box was because the drive started slipping, however it wasn't clear if it was the clutch or the overdrive (A Type). Either way the box had to come out. The clutch was fitted on 27th of April 1993 and has covered approx 95,000 miles. I acquired the car 4 years later and removed the engine and gearbox to replace the ring gear on the flywheel. I decided at the time to leave the clutch and only replaced the fork pin with a new hardened one. This decision has been vindicated as its been fine over all that time, but what to do now. What do you all think of the condition of the clutch, and would my best plan be to get it reconditioned, I would like to keep the Laycock cover .I can't see any reason for the drive slip from the clutch,the shaft , fork and pin are fine, any thoughts Thanks Cameron