JBRoberts Posted March 30, 2014 Report Share Posted March 30, 2014 Folks: I now have 25 test miles under my belt and things were going great except now I seem to have lost reverse gear for some reason. I installed a new rebuilt TR4 overdrive gearbox and it shifted very nicely. I did initially have reverse but now it only works when the ground is really flat. Tried reversing on a very slight incline and it does not go backwards but just whirs - not very loud whir but its there. Any ideas ? many thanks...JB Quote Link to post Share on other sites
marko Posted March 30, 2014 Report Share Posted March 30, 2014 Oh Dear! This sounds like the Overdrive has stuck in..... And if you have reversed the car then that can have catastrophic implications for the gearbox and overdrive... If it feels like the handbrake has stuck on when you try to reverse DO NOT CONTINUE!! Quote Link to post Share on other sites
peejay4A Posted March 30, 2014 Report Share Posted March 30, 2014 I know not a lot about the internals of overdrives but I'd hazard a guess that the unidirectional clutch has failed. Quote Link to post Share on other sites
marko Posted March 30, 2014 Report Share Posted March 30, 2014 You will need a specialist or someone familair with the TR Gearbox to have a look at it..... There is an inhibitor switch in the circuit and a "Valve" that may have stuck that releases the pressure in the overdrive....If this isn't working then the overdrive may remain "engaged" It will be ok going forwards but backwards......eeek very bad news! Quote Link to post Share on other sites
AlanT Posted March 30, 2014 Report Share Posted March 30, 2014 Dont think this is the OD, if the description is correct. It will reverse if the ground is flat. A jammed uni-clutch wont care how flat the ground is. I think this is the reverse gear selector which is not mating the gear fully. If you take the top plate of the gear-box you should be able to see if I am right. HOWEVER DONT DRIVE UNTIL YOU FIND OUT. This could go to bits easily. You might get in foward and reverse at the same time!! Quote Link to post Share on other sites
peejay4A Posted March 30, 2014 Report Share Posted March 30, 2014 I think Al might be onto something. When I installed my gear lever I assumed it was like the TR6 with a threaded stud going in from each side of the gear lever mainly because the studs came with the car. Actually it should have had a single long bolt right through the ball of the lever. The result was that I could lift the lever too far when selecting reverse so much so the the lever came out of the selector rods. Quote Link to post Share on other sites
JBRoberts Posted March 31, 2014 Author Report Share Posted March 31, 2014 Thanks fellas...time to take trans cover off which will be fun !. I'll let you know what I find..JB Quote Link to post Share on other sites
AlanT Posted March 31, 2014 Report Share Posted March 31, 2014 This may help: http://vintagetriumphregister.org/maintenance/ Quote Link to post Share on other sites
JBRoberts Posted March 31, 2014 Author Report Share Posted March 31, 2014 Fellas: I know the advice was to not touch the car but for the heck of it I wanted to see if the problem was there when car was cold. So I started her up after sitting all night, cold engine and tranny, and guess what the reverse worked. I backed down the drive to the slight incline on my cul de sac and it worked fine. When the problem occurred yesterday I had been bombing around for 15 miles or so everything was hot So does any of the above advice change or am I still into taking top off ? thank for your help...JB Quote Link to post Share on other sites
RogerH Posted March 31, 2014 Report Share Posted March 31, 2014 Hi JB, Have you got oil in the GB? Roger Quote Link to post Share on other sites
JBRoberts Posted March 31, 2014 Author Report Share Posted March 31, 2014 Roger...I did remember putting it in but I also seem to remember it did not take as much as I though it would. I'm going to check everything out this weekend to see what's going on..tks,,JB Quote Link to post Share on other sites
BrianC Posted April 1, 2014 Report Share Posted April 1, 2014 (edited) Remember that the overdrive gearbox takes 3.5 pints as opposed to 1.5 pints in a standard gearbox. It also takes a while to drain through, so recheck the level after half an hour or so if filling from empty or after draining. [And again after driving]. Edited April 1, 2014 by BrianC Quote Link to post Share on other sites
saggy Posted April 1, 2014 Report Share Posted April 1, 2014 Hmmm, I have just got the same problem ! Drives fine in any forward gear but just whirrs in reverse. I haven't really used the car since I've had it other than to just start, run round the house and warm it through regularly. I've always kept the overdrive lever in the down position which is my understanding that overdrive is DISENGAGED. (Lever up is overdrive engaged right?) Is it possible that the wiring could've been reversed so that in fact I've had overdrive engaged permanently??? Also, if the solenoid is faulty then isn't the hydraulic piston retracted by the return springs so that the default position DISengages overdrive? If it's the reverse gear selector mechanism, is that gearbox out time? Thanks Quote Link to post Share on other sites
JBRoberts Posted April 2, 2014 Author Report Share Posted April 2, 2014 Saggy et al: Now you got me thinking. My overdrive lever is UP position and I have not purposely tried the OD gears yet. I did a complete rebuild and so I'm testing things bit by bit. I'm not sure what the position of the lever should be for ON or OFF so would appreciate some thoughts. Knowing this and checking my oil this weekend may solve my problem Tks all... JB Quote Link to post Share on other sites
peejay4A Posted April 2, 2014 Report Share Posted April 2, 2014 (edited) The correct position is up for overdrive out, down for in. Regardless of that, the interlock switches on the gearbox top cover should prevent the overdrive from engaging in reverse or 1st (and 2nd on a J type). Edit: providing they are wired correctly. Edited April 2, 2014 by peejay4A Quote Link to post Share on other sites
JBRoberts Posted April 2, 2014 Author Report Share Posted April 2, 2014 Tks Peejay I can't remember but when you install the lever does it only go on one way so UP and DOWN don't get reversed ? JB Quote Link to post Share on other sites
saggy Posted April 2, 2014 Report Share Posted April 2, 2014 Pete Quoted: The correct position is up for overdrive out, down for in. Unquote In the TR owners handbook it says.... "move the lever UP to engage overdrive and down to release it" Like JBR I have not purposely tried the OD gears yet on the road and my overdrive lever is DOWN position as per the handbook. So just WHAT is the correct answer here for in/out up/down ? ? ? Saggy Quote Link to post Share on other sites
AlanT Posted April 2, 2014 Report Share Posted April 2, 2014 If I were you I would disconnect all electrical input to the OD solenoid until you find out what you are doing. Quote Link to post Share on other sites
peejay4A Posted April 2, 2014 Report Share Posted April 2, 2014 (edited) ...and to echo what Alan says, engine off, ignition on, put it in 3rd or 4th gear and operate the o/d switch. You should hear the o/d relay (if fitted) and the solenoid click. It should not click with the gear lever in 1st, reverse and 2nd on a J type o/d. I've had 3 TRs and it's always been down for o/d engaged. Perhaps they were all wrong. Edited April 2, 2014 by peejay4A Quote Link to post Share on other sites
JBRoberts Posted April 2, 2014 Author Report Share Posted April 2, 2014 Alan and Peejay Tks for your advice on this. Hopefully at the end of this we will know what we are doing but right now I don't know so appreciate all the learning JB Quote Link to post Share on other sites
AlanT Posted April 2, 2014 Report Share Posted April 2, 2014 (edited) Dont take chances with the OD being engaged when it shouldn't be. Especially in reverse. It will break something and will be expensive. READ ALL THIS. http://www.buckeyetriumphs.org/technical/AOD/AOD1/AOD1.htm and the follow on episodes too if you possibly can. This was written by a really top-flight mechanical engineer who these days is nameless, but I happen to know who it was and what they did for a living, T'aint the kind of thing you can make mistakes with! Oh and beware that about 3/4 of the parts in a gbox are spinning even if you are parked and in neutral. So if something is loose in there it can smash the thing even if you don't go anywhere but just have the engine ticking over. Edited April 2, 2014 by AlanT Quote Link to post Share on other sites
dingle Posted April 2, 2014 Report Share Posted April 2, 2014 If you read the section on OD trouble shooting in the Buckeye articles, the most likely cause of slipping in reverse is weak clutch release springs. This makes sense as it is the springs that force the clutch inner linings against the annulus that provides the drive in reverse. Berry Quote Link to post Share on other sites
Graham Harris Posted April 3, 2014 Report Share Posted April 3, 2014 It also provides the drive in forward as well, so if it goes forward and not back the problem is some where else. Graham. Quote Link to post Share on other sites
Lebro Posted April 3, 2014 Report Share Posted April 3, 2014 Ah, but if it fails in forward, the one way clutch carries the drive through. Bob. Quote Link to post Share on other sites
AlanT Posted April 3, 2014 Report Share Posted April 3, 2014 Yes this is correct. But the uniclutch is only intended for intermittent drive during OD engagement. The friction linings are the primary grip. I am beginning to think the linings maybe worn out. The original post only says a rebuilt gbox. Perhaps the OD got left alone? Quote Link to post Share on other sites
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