Section : Overdrive

Overdrive has fallen out with the Gearbox! 

Posted By : Philip Wright, 19-Dec-2003, 07:29pm

Hi Guys

I'm in the process of changing the gearbox on my MKIV spitty, but i'm having difficuly mating the overdrive to the new box. I've installed the pump cam with the chamfered edge outermost, and set it with the smallest part of the journal facing downwards so that it clears the cam. I can get the splines to mate in the overdrive, but I cant get the overdrive the last inch or so onto the gearbox. I guess it's the bearing in the end of the overdrive that's catching, so I obviously dont want to damage it. Incidentally, its a 3 rail box and a D type O/D.

Also, since installing the box i've noticed the o'd works fine when first engaged, but then nothing happens. I know this fault is electrical; has anyone got any clues as to how the relay should be wired up - the wiring loom is all new, as is the relay.

Any thoughts would be most appreciated as i'd like to get the car on the road asap to enjoy some top down winter fun!!!

Phil - '74 Spitty

• Overdrive has fallen out with the Gearbox! 

  Posted By : Tim Willis, 19-Dec-2003, 09:39pm

  Philip,
  
  If you tip the overdrive unit up and look into it you will see two sets of splines which have to slide ont the mainshaft. If they are not perfectly aligned then it will get stuck as you describe. Using a long flat blade screwdriver carefully align the bottom set of splines, they are stiff but will move. Now try fitting the OD, if it does not go straight on give the output flange a wiggle, if it doesn't now drop into place lift it off again, realign splines and try again.
  
  I'm not sure I understand your operating fault from your description, but there is a simple diagram in the haynes manual to show you how to connect your relay, inhibitor switch etc.
  
  Tim
  Willow Triumph
  

  • Overdrive has fallen out with the Gearbox! 

    Posted By : Philip Wright, 19-Dec-2003, 10:46pm

    Tim,
    
    Many thanks for that, i'll give it a try tomorrow morning and let you know how I get on!
    
    Regards, Phil

    • Overdrive has fallen out with the Gearbox! 

      Posted By : Philip Wright, 22-Dec-2003, 09:19pm

      All working guys
      
      Got the splines to line up, and eventually got the engine to mate with the gearbox on the second attempt. The O/D box is a heavy old beast when you're trying to put it in single handedly!
      
      The O/D makes a huge difference to the car - now does 70 at just over 3k RPM; used to do 50 at that speed!
      
      Phil; '74 Spitty, Roof Down Brrrrrr!

      • Overdrive has fallen out with the Gearbox! 

        Posted By : Andrew Stanton, 13-Feb-2006, 08:05am

        Indeed, I've tried to refit a gearbox and overdrive unit by myself. Frankly, I don't recommend it. The confined access together with the lowness of the vehicle in the first place is an invitation to spend a couple of weeks flat on your back watching the TV through a mirror.
        
        Get a mate to help you. Overdrive units are replacable! Spinal columns are not!
        

        • Overdrive has fallen out with the Gearbox! 

          Posted By : Ian Mulford, 13-Feb-2006, 10:25am

          I think that post must get the award for the longest follow-up being as the original was POSTED IN 2003!!

          • Overdrive has fallen out with the Gearbox! 

            Posted By : Don Cook, 13-Feb-2006, 01:51pm

            Perhaps Andy spent two or three years in hospital??