PhilJane Posted April 10, 2011 Report Share Posted April 10, 2011 Hi All, Today has been a great day in the UK with clear skies and sunshine with temperatures above 20C, so what better than to take the hood off and go for a drive in the English countryside. All was going well with the car driving superbly until I tried to engage reverse gear.... All forward gears are fine and managed to select reverse gear with no problems but when releasing the clutch gave a mechanical clunking noise with the car jumping backwards and in a binding, distressed fashion. Could this be a CV joint, driveshaft or differential or even the gearbox? Intend to get the back end up on axle stands and have a good look around but would appreciate any comments from members. Phil. Quote Link to post Share on other sites
stuart Posted April 10, 2011 Report Share Posted April 10, 2011 Hi All, Today has been a great day in the UK with clear skies and sunshine with temperatures above 20C, so what better than to take the hood off and go for a drive in the English countryside. All was going well with the car driving superbly until I tried to engage reverse gear.... All forward gears are fine and managed to select reverse gear with no problems but when releasing the clutch gave a mechanical clunking noise with the car jumping backwards and in a binding, distressed fashion. Could this be a CV joint, driveshaft or differential or even the gearbox? Intend to get the back end up on axle stands and have a good look around but would appreciate any comments from members. Phil. That sounds rather like the overdrive is still engaged. Do not reverse any more until you have established why. Could be electrical short holding the solenoid in or it could just be the cone clutch stuck if it has been relined recently. Stuart Quote Link to post Share on other sites
RogerH Posted April 11, 2011 Report Share Posted April 11, 2011 ...if it is the overdrive and you have recently replaced the solenoid it may be the rubber boot holding the plunger up. Some of the rubber boots are very stiff. Simply cut some of the rubber away from the plunger. Roger Quote Link to post Share on other sites
PhilJane Posted April 11, 2011 Author Report Share Posted April 11, 2011 (edited) Stuart, Roger, Thanks for your comments and appreciate your good suggestions. The overdrive was working nicely literally minutes before encountering the reverse gear problems. The gearbox was also running fine. Could the overdrive unit suddenly lock like this? No recent work on the overdrive unit and it has been working well until this issue arose. Edited April 11, 2011 by PhilJane Quote Link to post Share on other sites
John Morrison Posted April 11, 2011 Report Share Posted April 11, 2011 Absolutely and it is the most horrible, scary noise. had this once, O/D stuck in, manually pulled the lever up to get home, can't just remember the cause but it was a home fix, and there was no permanent damage, just to cheer you up! John. Quote Link to post Share on other sites
Don Elliott Posted April 11, 2011 Report Share Posted April 11, 2011 Phil - I agree with all the above. But you mentioned that last week you had some electrical issues and perhaps your electrician did something to cause this while he was working on your horn and directional signal wiring problems. If you disconnect the wiring to the overdrive and keep the open wire ends insulated from anything, you may find the answer. I had the rubber boot jam the solenoid upwards, so I removed it. The solenoid plunger gets a bit oily but I never had a problem with the rubber boot completely removed. If for some reason, the cross-shaft with the lever on the right side has become mis-adjusted, it's possible that your overdrive is "ON" in all gears including 1st and reverse. If the speedometer in first gear doesn't agree with the usual RPM, then the O/D is "ON" in 1st gear. It's in reverse that the worst happens. !st gear in overdrive is not a problem as long as you are driving very conservatively at reasonably low RPM engine speed. I had this horrible noise in reverse while in 2000 while driving in Yellowstone National Park in Wyoming, 2500 miles after leaving home. In forward, I drove for two more days before arriving at VTR in Portland, Oregon. But I never put it into reverse again till I stripped it all down after VTR was over. It has been fine ever since. Quote Link to post Share on other sites
Guest ntc Posted April 11, 2011 Report Share Posted April 11, 2011 Hi All, Today has been a great day in the UK with clear skies and sunshine with temperatures above 20C, so what better than to take the hood off and go for a drive in the English countryside. All was going well with the car driving superbly until I tried to engage reverse gear.... All forward gears are fine and managed to select reverse gear with no problems but when releasing the clutch gave a mechanical clunking noise with the car jumping backwards and in a binding, distressed fashion. Could this be a CV joint, driveshaft or differential or even the gearbox? Intend to get the back end up on axle stands and have a good look around but would appreciate any comments from members. Phil. A type yes? if so they can stick with lack of use,if you cannot push the car backward in neutral it is stuck if so get BFH and strike the metal sandwich plate until you hear a click and try again Quote Link to post Share on other sites
PhilJane Posted April 11, 2011 Author Report Share Posted April 11, 2011 All, Thanks for the good feedback. It sounds as though it is the overdrive unit, as you have all identifed. Managed to push the car backwards in neutral so perhaps no need for the BFH treatment just yet! Any recommendations on getting access to the overdrive unit? Is it better from underneath or from above? Thanks, Phil. Quote Link to post Share on other sites
stuart Posted April 11, 2011 Report Share Posted April 11, 2011 All, Thanks for the good feedback. It sounds as though it is the overdrive unit, as you have all identifed. Managed to push the car backwards in neutral so perhaps no need for the BFH treatment just yet! Any recommendations on getting access to the overdrive unit? Is it better from underneath or from above? Thanks, Phil. Best to remove cover so you can get access to everything. Stuart. Quote Link to post Share on other sites
foster461 Posted April 11, 2011 Report Share Posted April 11, 2011 Best to remove cover so you can get access to everything. Stuart. ..and I would suggest using a drift of suitable dimensions so that the impact is applied to the brake ring and not the aluminum case as well.. Stan Quote Link to post Share on other sites
vivdownunder Posted April 12, 2011 Report Share Posted April 12, 2011 Phil, you could try a simple test on the O/D solenoid. While at rest engine off, put the car in top gear. Turn the key to ignition on. Kneel beside the car and flick the O/D switch. You should clearly hear the solenoid operating. That will eliminate a sticking solenoid as the cause. Obviously be careful not to turn the key to start. Once you are sure the O/D is off, test the car again for the reverse problem. Be careful using what our American colleagues refer to as a BFH. Sometimes just a light tap will free a jambed O/D. I would use my Thorex wire wheel hammer with nyloc striker pads. If a tap frees the O/D, drop the oil at the big O/D plug and check for particles in the filter and/or on the magnet. Could be a sign that something has broken. Regards, Viv. Quote Link to post Share on other sites
PhilJane Posted April 17, 2011 Author Report Share Posted April 17, 2011 Thanks to all for the very good advice. I have been under the car this weekend and had a good inspection of the gearbox and overdrive. There was evidence of a leak from the brass drain plug on the overdrive, so wasn't so surprised when I collected less than the anticipated 2 litres of gearbox oil. There was no material in the brass caged basket although these was minor debris in the cup of the brass drain plug on the overdrive, which looked as though it had been there quite a while. Reading a few references, it appears that oil level is critical, so replaced the oil with 20W/50 which the original manufacturer's recommend, although have seen many recommendations to use EP80 or EP90 gear oil, which is virtually at the other end of the lubrication spectrum! Are there any clever methods for filling with gearbox oil from underneath the car? Driving the car again has confirmed that the solenoid is working well and overdrive unit working, but a tentative effort to engage reverse has shown that the override is not working. This suggests an electrical problem which is allowing o/d to operate in 1st and reverse gear? Phil. Quote Link to post Share on other sites
johnny250 Posted April 18, 2011 Report Share Posted April 18, 2011 (edited) Thanks to all for the very good advice. I have been under the car this weekend and had a good inspection of the gearbox and overdrive. There was evidence of a leak from the brass drain plug on the overdrive, so wasn't so surprised when I collected less than the anticipated 2 litres of gearbox oil. There was no material in the brass caged basket although these was minor debris in the cup of the brass drain plug on the overdrive, which looked as though it had been there quite a while. Reading a few references, it appears that oil level is critical, so replaced the oil with 20W/50 which the original manufacturer's recommend, although have seen many recommendations to use EP80 or EP90 gear oil, which is virtually at the other end of the lubrication spectrum! Are there any clever methods for filling with gearbox oil from underneath the car? Driving the car again has confirmed that the solenoid is working well and overdrive unit working, but a tentative effort to engage reverse has shown that the override is not working. This suggests an electrical problem which is allowing o/d to operate in 1st and reverse gear? Phil. hi Phil, Bit puzzled, You mention that the solenoid and overdrive is working well? so it's unlikely to be electrical. Whilst under there, did you check that it is moving the operating lever correctly and not slipping on the spindle or similar? and not operating when you select reverse? The inhibitor switch(es) on the gearbox should prevent operation in reverse etc operation, but even if they are faulty, as long as the overdrive is switched off, it should not have overdrive engaged to prevent reverse.....sounds more like an internal mechanical problem. If you slacken the pinch bolt on the solenoid operated spindle, it should come out of overdrive enabling reverse, (unless stuck as mentioned above) If you cannot free the O/D clutch by striking the brake ring (weak return springs?), then there could be a blockage in the operating valve, accessed through the screw in plug on the RH topside. Fish out the ball/spring and long valve with a very small magnet or piece of bent wire. There is a very fine hole in the valve spindle that can block easily. You won't of course collect two litres if only draining from the overdrive plug. There will be more in the gearbox...straight 40 gearbox oil is recommended I believe (not EP anything) but 20/50 will work....but we won't start that one again . john Edited April 18, 2011 by johnny250 Quote Link to post Share on other sites
RogerH Posted April 18, 2011 Report Share Posted April 18, 2011 (edited) Hi Phil, at first I read your override as overdrive and got me all curfuddled. The override (inhibitor switches) should only allow (2nd), 3rd & 4th to work. If you can select 1st or Reverse you need to get access to the top of the box and sort the wiring. Roger Edited April 18, 2011 by RogerH Quote Link to post Share on other sites
PhilJane Posted April 18, 2011 Author Report Share Posted April 18, 2011 (edited) Hi John and Roger, Thanks for your comments and suggestions. I did drain the gearbox and overdrive unit and got substantially less than 2 litres. Seeing the oil level was low, I was keen to fill with fresh oil and see if that had cured the problem. On the road the o/d worked well, switching in and out in 2nd, 3rd and 4th gears. Reversing was fine with the overdrive switched off, although I did tentatively try reverse very briefly with the overdrive switched on and the old symptoms were shown. Does this suggest that it is the inhibitor switches and not the relay or a faulty earth? Phil. Edited April 18, 2011 by PhilJane Quote Link to post Share on other sites
johnny250 Posted April 18, 2011 Report Share Posted April 18, 2011 Oh I see! One of the gearbox interlock switches (they should be wired in parallel) looks like it's probably stuck closed....? john Quote Link to post Share on other sites
88V8 Posted April 18, 2011 Report Share Posted April 18, 2011 .... replaced the oil with 20W/50 Phil. I have seen past comments to the effect that 20/50 oil is OK provided it's not engine oil. If you used 20/50 gearbox oil, well, fine. One of the gearbox interlock switches (they should be wired in parallel) looks like it's probably stuck closed....? Or has been 'temporarily' bypassed to check something? What was your electrician doing? Ivor Quote Link to post Share on other sites
PhilJane Posted April 20, 2011 Author Report Share Posted April 20, 2011 Thanks for all the great correspondence on my overdrive issues. The feedback was sufficient to help diagnose something was wrong with the electrical side of the overdrive wiring and I confess to taking the car to my local auto-electrician who rewired the overdrive switch, relay and interlock switches, such that 1st gear and reverse can now be used without any problems. (no sound of the solenoid moving in these gears). I am now in a dilemna over whether to go with 20W/50 Valvoline R engine oil which Don has had good experience, or go for the 30 or 40 grade gear oil. Are there favoured brands of gear oil? Thanks all, Phil. Quote Link to post Share on other sites
vivdownunder Posted April 20, 2011 Report Share Posted April 20, 2011 Phil, Castrol VMX 80 gear oil is a current favourite (previously Penrite Gearbox Oil 30 or 40), based on evidence collected from gearbox strip downs. Significantly reduced grey material in the oil when drained. Engine oils have been used without problems, but the additives for preserving cat converters, carbon dispersants etc., aren't really needed in a gearbox. Viv. Quote Link to post Share on other sites
PhilJane Posted April 22, 2011 Author Report Share Posted April 22, 2011 Hi Viv - Thanks for your recommendation on the oil for the gearbox and overdrive unit. Do you (or other members) know the Castrol (or other manufacturers) product which is the equivalent to Castrol VMX 80? I believe it is hard to find in the UK. Is there a universal recommendation on oil for the differential? Many thanks, Phil. Quote Link to post Share on other sites
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