Section : Overdrive

Overdrive sticking on 

Posted By : David Cox, 14-Jun-2007, 05:02pm

• Overdrive sticking on 

  Posted By : Mark Astley, 14-Jun-2007, 05:15pm

  Definately do not drive the car in reverse if the overdrive is in, you'll wreck the clutch.
  
  I think the first thing I'd do is drive the car with the tunnel cover off till the fault shows up again and then stick a multimeter on the solenoid feed and see if there is still 12v there with the switch in on and off, if there is, it's a switch fault. If the 12v goes and the solenoid doesn't click out, there is a problem with the solenoid sticking on or the O/D internals not releasing.
  
  I can't remember where the solenoid is on a J, but you could run it with the little cover off and see how the solenoid and arm it operates moves. It may not retract enough when warm to disengage. Would be worth marking the off position first.
  
  Hope that helps.
  Mark
  

  • Overdrive sticking on 

    Posted By : Mark Hammond, 14-Jun-2007, 05:44pm

    Might be the inhibitor switch as well, I had this problem with a nearly new Dolomite Sprint way back. I had overdrive on all gears including reverse, but thinking about it, mine could switch off when hot, just not when cold. Do not run with overdrive on in any gear except with 3rd and top as you will knacker the overdrive for sure!
    As a thought, have you check the oil level in the gearbox?
    
    Mark

    • Overdrive sticking on 

      Posted By : Leon Guyot, 14-Jun-2007, 05:57pm

      What oil are you using in the gearbox?
      
      Some people have been using engine oil in overdrives and this has lead to the problem you are describing.
      
      For Triumphs it should be per factory recommendations
      
      EP90 Gearbox Oil, GL-4.
      
      Nothing else.
      
      L&195;&169;on

      • Overdrive sticking on 

        Posted By : John Davies, 14-Jun-2007, 07:08pm

        My Haynes manual list the following under "Overdrive fails to engage"
        Faulty solenoid
        Incorrect solenoid iperating lever adjautment
        Clucth cone stick in engaged position.
        
        The last covers a multitude of sins.
        I'm no expert, but I know that the clutch is kept engaged by oil pressure from the eccentric oil pump.
        If that pressure cannot escape from the actuating pistons, the O/drive will not disengage.
        The oil escapes via the Relief valve
        As the clutch wears, the notorious "black hairy bits" escape into the oil, and should be trapped by the filter, but could be blocking the valves.
        Checking the filter is easy to do, even on the car, so check that first.
        Lots of "BHB"s mean a worn out clutch, so maybe the best thing is a rebuild.
        As a non-expert I'd better not go on, but see your manual and the "Relief valve plug".
        
        John

    • Overdrive sticking on 

      Posted By : Chris Taylor, 14-Jun-2007, 06:59pm

      Can't be the inhibitor switch. Even if that remained permanently switched "on", operating the o/d switch would break the circuit and de-energise the solenoid.
      Providing you don't use anything like full throttle, you should not cause damage in using o/d in 1st or second occasionally, but ANY reverse movement, whether under power or not, will knacker the unidirectional clutch at the heart of the overdrive.
      Low oil level usually results in a lack of hydraulic pressure in the o/d and it then fails to engage, or slips when engaged. It's more likely to be either a sticking solenoid or some muck in the hydraulic system which does not allow pressure to release when the solenoid disengages.
      Not sure I'd fancy driving for half an hour with no gearbox tunnel, but it would be the only way to check whether there is 12v at the solenoid or not. Before doing that, I would suggest you check that you can hear the solenoid click in and out when cold. Not sure about the J type (which is on the opposite side of the gearbox from the driver) but you can certainly hear the D type when the engine is off. Turn ignition on, place gearlever in 4th and operate o/d switch on AND off. If you CAN hear it click in and out, then drive the car until the problem arises. IMMEDIATELY coast to a stop and turn off the engine and repeat the above (remembering to turn the ignition back on!) If you CAN hear the solenoid click in and out, then the problem must be in the hydraulic circuit in the o/d. If you CAN'T hear it click, then the problem is most likely electrical and the solenoid is either still receiving 12volts (or enough to remain engaged) or is physically stuck. Not sure how the o/d is fused, but if you can either disconnect a part of the supply to the o/d (easier with a column switch on a Vitesse!) or temporarily remove the fuse, and drive off again, knowing for SURE that the solenoid is electrically isolated will help to determine if the solenoid is being wrongly energised or if it is physically stuck.
      If the solenoid is being energised when it should not be, you need to systematically trace all the wiring and connections. It might be simpler to replace the whole o/d loom, but first place to look should be within the gearlever and operating switch.
      If the solenoid is physically stuck, you would have to remove it (not so easy with a J type) and examine it as to why. It is direct acting so there is no fork and lever to stick as in D type.
      If the problem is hydraulic, you could try cleaning the filter and changing the gearbox oil. You may also be able to extract the operating valve ball and see if there is any obvious obstruction there. Beyond that, an exchange reconditioned overdrive would be the most cost effective route.

      • Overdrive sticking on 

        Posted By : David Cox, 14-Jun-2007, 07:32pm

        Hi,
        
        Wow, thanks for all your suggestions, it gives me a good start in finding the problem. As for Oil level, I beleive that if it was low, the o/d would not engage. I can't recall exactly what oil I put in, but do know for sure it was NOT engine oil, and was Gearbox oil.
        
        I have considered cleaning the filter, and will be one of the first things I try.
        
        Im on holiday very shortly, so will probably leave the car until I return, but will keep you updated with progress.
        
        Thanks once again.
        
        Dave

        • Overdrive sticking on 

          Posted By : Chris Davidson, 14-Jun-2007, 10:00pm

          I had this problem with my Spitfire last year, after checking everything at the gearbox end traced it to the switch on top of the gear stick. The contacts had corroded and bridged making a permenant contact.
          
          Chris

        • Overdrive sticking on 

          Posted By : Clive Speaks, 15-Jun-2007, 09:38am

          I had a similar problem on my wife's 2000 saloon and it came down to the Solonoid sticking. Be careful though as this will bugger up your O/D PDQ. We had to source another O/D and solonoid in the finish. Also check the cabling down the inside of the gear stick. This does fray and then short although normally the O/D cuts in and out by itself giving a very interesting drive

• Overdrive sticking on 

  Posted By : Mike Crewes, 15-Jun-2007, 08:52am

  Dave
  
  I have not read this entire thread, so my experiences may already have been covered.
  
  When I bought my Stag (J Type O/D) the O/D was very sticky, both in and out and this cleared with use. Last spring the same happened and it eventually cleared with use. This spring the slow going in cleared, but it was VERY sticky coming out and I didn't want to cause lots of damage. DO NOT REVERSE WITH O/D ENGAGED IT WILL DESTROY ITSELF IN ONE TURN.
  
  I went to a Stag specialist who checked all the usual things, oil level and pressure, cleaned filters etc. They came to the conclusion that it was the soleniod, so they changed it (they had an idea it was beforehand, but went through the motions just in case). Problem instantly cured.
  
  If you decide to change the solenoid, clean thoroughly (not with a rag) the part that goes into the O/D, even if it is new. The smallest piece of dust will prevent it working properly and may damage it.
  
  Hope this helps.
  Regards
  Mike

  • Overdrive sticking on 

    Posted By : Peter & Mick Lewis, 15-Jun-2007, 04:56pm

    both d and j can have corroision on the solenoid core makes it stiff and slow moving,
    Just take the little b**ger off and thats a task in its own right, you will have to jack the box up to get on the screws its not easy
    and clean it up with some flour paper or scotchbrite pads peter
    

    • Overdrive sticking on 

      Posted By : David Cox, 15-Jun-2007, 07:04pm

      Hello again,
      
      I have been impressed with the response I have received on this subject, thanks very much.
      
      In the past, I have been able to quite clearly hear the soleniod clicking in/out with just the ignition on. But now, even with the tunnel removed, there is the very slightest sound when switching it in/out. I plan to check the filter, feed to the soleniod, and oil level, and then I may have to bight the bullet and invest in a new solenoid. Until then, the car will be unused.
      
      I bought a new o/d switch that fits into the top of gearstick last year, and that is still very clean, so do not suspect this to be the cause. However, I can always temporarily fit a different switch during tests, just to prove this is the case.
      
      Would just like to clarify one thing, should the car not be PUSHED backwards, with the car in Neutral??
      
      As I have said before, I will keep you updated with my progress, and thanks all again.
      
      Dave

      • Overdrive sticking on 

        Posted By : Chris Taylor, 16-Jun-2007, 04:49am

        No, the car should NOT be moved backwards, even pushed, if the overdrive is engaged. The problem is a unidirectional clutch at the end of the gearbox(?) shaft. This is a bit like a ratchet (but uses rollers so it has no backlash and is smoother). This transmits drive while the overdrive cone clutch is moving from direct drive to overdrive and so no torque is being transferred through the OD clutch. When direct drive is engaged, everything in the OD is turning at the same speed (that of the gearbox output shaft) so no problem (in either direction). But when OD is engaged, the OD OUTPUT is turning faster than the input (which is what the OD is all about!). When running forward, the OD output shaft runs faster than the end of the gearbox output and the unidirectional clutch "freewheels". However, being a ratchet type arrangement, if you try to do this when going backwards, the roller clutch cannot freewheel. The end result is the OD gears and cone clutch try to make the output turn faster than the input, while the roller clutch tries to make them turn at the same speed. Something has to give, and it is nearly always the roller clutch. Being right in the middle of the OD assembly, total dismantling is needed to replace it, and the fragments of metal produced when it breaks up can cause damage to other parts of the OD.
        The absence of clicking is a clear sign that either the solenoid is receiving power when it should not, or that it is physically stuck.
        If you have the tunnel off, it might be worth engaging 4th and the OD switch ON, then disconnecting the battery (or some other part GUARANTEED to isolate any possible feed to the solenoid). Then touch the battery lead on and off the battery terminal. If you hear the solenoid click in and out, then you can be reasonably sure the problem is a wiring one. If there is NO sound from the solenoid when you can be sure you are making and breaking an electrical supply to the solenoid, then it suggests the solenoid is sticking. Before resorting to a new one, it would be worth removing the plunger from the solenoid and seeing if there is any corrosion on the plunger or in the bore. (With the price of a new solenoid it's worth trying to save the old one!)
        If the overdrive is believed to be engaged, you MAY be able to release the hydraulic pressure by easing the cap above the operating valve, but you MUST check with the manual or an OD specialist like OD spares in Sheffield before doing this as you are dealing with several hundred psi so be careful!

        • Overdrive sticking on 

          Posted By : David Cox, 07-Jul-2007, 01:00pm

          Hello again,
          
          I have returned from holiday, and have now started work on my Overdrive. I have a couple of questions Im hoping you can help me with. I have taken the O/D Solonoid off, and applied power to it on the bench. At first there was no sign off life. Then I pressed the plunger down, and re-applied power. The solonoid could then be heard clicking. It does appear to be getting stuck on sometimes.
          
          1) I have found a spare solonoid, and tried it on the bench as well. This one sounds more positive in clicking in/out, but when you shake it, it rattles. My original one does not. Should there be a rattle heard when shaken????? I am thinking about trying this one on car.
          
          2) What is the best way to clean out the original solonoid?? I have taken the circlip off the end, but do I need to knock out the pins around the casing. Or can I just spray WD40/Electrical cleaner all around trying to get it inside. Whats best to use to clean it with??????
          
          Any suggestions would be appreciated.
          
          Thanks
          
          Dave

          • Overdrive sticking on 

            Posted By : Chris Taylor, 07-Jul-2007, 04:29pm

            Afraid I am none too familiar with the J type solenoid, but I WOULD expect the plunger to rattle a little. Anything else rattling would be bad news, but since it appears to be working it seems unlikely that any electrical bits inside are loose. I would suggest that you try this in the car and keep your fingers crossed. As long as the supply is fused, the worst that can happen is that either the overdrive will not engage or not stay engaged, or you will blow a fuse.
            I would have thought that you only needed to remove the circlip to remove the plunger, but I could be wrong. Squirting a small amount of WD 40 inside won't do any harm, especially if you can get it all to drain out afterwards. However I would expect the problem to be surface corrosion on the plunger (or possibly the inside of the core) and you will only be able to remove this physical obstruction by removing the plunger. The WD40 will probably help in loosening the plunger to achieve this.

            • Overdrive sticking on 

              Posted By : David Cox, 10-Jul-2007, 07:32pm

              Hi everyone,
              
              Just posting to let you know my car now appears to be working fine. I put my spare Solonoid on the O/D, and it now switches in/out well.
              
              I plan to clean my original one up so that I still have a spare should I require it.
              
              I would like to take this opportunity to thank everyone that posted with their suggestions. I was very impressed with the response I got, and there were plenty of ideas to look into.
              
              I now hope we all get the summer we have been waiting for, to make driving our cars that more enjoyable.
              
              Thanks again,
              
              Dave