Section : Gearbox

Overdrive engagement

Posted By : Javed Aslam, 04-Sep-2005, 12:27pm

• Overdrive engagement

  Posted By : Lindsay Dearing, 04-Sep-2005, 02:41pm

  Javed, the symptoms you describe suggest a low oil level. I suggest you drain out what is in there (and the quantity that drains out will tell you) and replace with fresh Hypoid EP90. You will need upto 1.5 litres for the J type and gearbox. At worst you will have had an oil change, at best a cure for the problem. If that does not fix it then you will probably have a pressure problem due to worn 'o' rings on the pistons; worn oil pump, or blocked filter. See how you get on.

  • Overdrive engagement

    Posted By : Javed Aslam, 04-Sep-2005, 03:14pm

    Thanks
    javed

    • Overdrive engagement

      Posted By : Van Hamlin, 04-Sep-2005, 09:46pm

      The GT6 manual (and probably the Vitesse manual too) suggest that the minimum speeds for engaging overdrive are 30mph in 3rd and 40mph in 4th. These works out as a bit over 2000 rpm before the overdrive is engaged and a bit under 2000 rpm after the overdrive is engaged.
      The overdrive pump is driven by the output shaft of the gearbox, so at lower speeds you are not pumping much oil, which may be why it doesn't engage, or takes a bit longer. I wouldn't necessarily say there is anything particularly wrong with seals etc in the overdrive.
      Regards
      Van
      

      • Overdrive engagement

        Posted By : Nigel Gibbins, 04-Sep-2005, 09:58pm

        Of course, if you're only doing 1000 (or 2000) rpm then you don't need he overdrive anyway.... I only 'kick' mine in when the revs reach 4000+

        • Overdrive engagement

          Posted By : Javed Aslam, 05-Sep-2005, 12:51pm

          Thank you again
          Javed