Author Topic: MK 1 gearbox.  (Read 2583 times)

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Offline george sutton

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MK 1 gearbox.
« on: 07 Jun 2012 at 17:13 »
Overhauling my MK1 gearbox, i find that a previous rebuilder has left approx. .025"backlash in the sleeve pinion (38485) /shaft and clutchdog assembly. Other than the obvious , that it can float in / out of the clutch plate itself, is this deliberate ?   I would think not myself.  If not , then can i remove the assembly and just get away with reshimming at the retaining plate (25967) ??Denis.S.

Offline george sutton

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Re: MK 1 gearbox.
« Reply #1 on: 08 Jun 2012 at 03:17 »
Hi guys.  Sorry, but i used the wrong termology here by saying BACKLASH,  ( must be getting too much of it in my old brain these days),  i sould have said ENDFLOAT in the primery input pinion.    Personnally i dont like this kind of movement on a shaft because it eventually allows small amounts of oil to get through a seal, and on this box it is only a felt seal.  Denis.s

Offline eddie

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Re: MK 1 gearbox.
« Reply #2 on: 08 Jun 2012 at 15:37 »
Denis,
        The primary shaft is stepped down to locate a single row of rollers - the outer track is the same width and trapped between hardened thrust washers, so the length of the rollers will determine the endfloat on the primary shaft. Personally, I wouldn't worry about 25 thou of endfloat providing top gear selects correctly. The endfloat is not likely to affect the operation of the oilseal as the movement will be axial - the bronze bearing between the primary shaft and the mainshaft controls the amount the primary shaft can move out of alignment. If you decide you want to reduce the endfloat, this can only be done by fitting longer rollers - but beware, 10 thou longer rollers will reduce the endfloat by double that amount. You should not attempt to achieve zero endfloat - that will probably result in the front bearing running tight and seizing up. In any case, it is not possible to adjust the endfloat by shimming the retaining plate, but the increased endfloat could be caused if a previous 'repair' has resulted in the retaining plate being dished. If this is the case, Postwar Spares should be able to help with a replacement.
   Regards,
               Eddie.

Offline george sutton

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Re: MK 1 gearbox.
« Reply #3 on: 08 Jun 2012 at 17:59 »
Hi Eddie. what you say makes a lot of sence, as usual. How ever i was promted to ask this, because an old mk1 i have as spare has absolutely No end float on that primeray shaft. (cant swap the spare box as its nack----d in other areas.) . However, for those of you who may remember all the problems i had after the purchase from cotswold clas--cs, in 2009 and reputed work done by certain members, it just had to be engine and g/box out now for a real going over. Hopefully engine now ok, and this g/box overhaul has revealed the horrible grinding noise from the g/box upon changing down has been because i found the final drive pinion was loose. i.e nut undone, and locking washer not turned over. who knows, i might even make it to an event this year! thanks Eddie. denis.s

 

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