AR7E - Alcester Racing 7's Equipe
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This walkthrough relates to the standard five-speed 'Type 9' gearbox commonly used in Caterhams past and present. Along with differential oil, gearbox oil does not need regular replacement in the way that engine-oil does - this is mainly because it does not come into contact with nasty by-products of the combustion process. You might find, however, that over a period of time, the gearbox oil level might need a top-up due to either oil being lost through minor leaks in the propshaft, or speedo-drive seals. Also in keeping with the standard differential, there is no drain plug or easy mechanism to check the oil level - you basically just top it up until oil overflows through the filler plug... So what is the problem? AccessThe gearbox filler plug is extremely difficult to access - as the following picture suggest...
<Click Image for Full Size> This picture doesn't actually show the full horror of the situation - because the chassis in question is a race chassis - and as such has a shorter passenger footwell than standard road cars (this facilitates a lower battery position for a better center of gravity). In most road cars, the footwell will extend forward of the red wire in the picture above and will block out all access routes other than from directly underneath the car. To compound matters, there is very little space (approximately an inch) between the side of the footwell and the filler plug - and so normal tools (a 10mm hex/allen key is needed) will not fit... Four options result: an allen key can be cut down to size, a set of 10mm nuts can be firmly fixed to a bolt (6mm diameter) - and this can be manipulated into the plug using a spanner, a professional mechanic can be hired, or an access hole can be made in the side of the footwell. Allen Key...Now, cutting down an allen key requires quite a lot of effort and a reasonably large number of hacksaw blades (allen keys are hardened...) - but if you have the facilities - go ahead. Actually, what you want to do is to cut an inch or so off the allen key handle and then use a 10mm ratchet spanner to manipulate it - this saves you from having to remove the key for each partial revolution. ...or Nut and BoltThe nut-and-bolt approach is very similar (basically you screw four or five M6 nuts very tightly onto a bolt and then use the ratchet spanner approach as outlined for the cut-down allen key above... ...except that when we tried it, the nuts undid themselves from the bolt before the filler plug started to move! ...or cashThe money-no-object option can be discarded out of hand - if you are reading this, then you probably want to do the job yourself and save some cash and hassle... ...so if cutting allen keys isn't your idea of fun, we'd recommend creating an access hole in the passenger footwell... ...or an access hole
<Click Image for Full Size> What we did was to peel the carpet back from the side of the transmission tunnel and then to drill a small (2mm) pilot hole where we thought the filler-plug was roughly. It took approximately two attempts before we were happy -and then we used a step-drill to enlarge the hole until we could gain decent access though to the plug. The access hole will be filled with a rubber grommet when not in use, in order to reduce water ingress. Once the plug has been removed, it is a relatively simple activity to get under the car and pump some oil into the hole until it starts to overflow (safety note - it's a good idea to wear some safety glasses - it's easy to get some in your eye ;-} ) We used the same Machine Mart oil can (with thumb-pump) and flexi-spout as we used to top the differential up - this part of the procedure really was pretty painless (apart from the oil in the eye...). Once you are done, refit the filler plug, grommet and tunnel carpet, and off you go... |
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