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Crunchy 4 speed(s)?

Posted: 09 Dec 2010 02:44 pm
by valman
another quick one from me on some finding i've made, is it just my luck or are the 4 speed boxes always shagged? becuase both the cars ive had with the 4 speed crunch into 3rd. violently. no matter how farf the clutch is pressed. and i did do a search but only found "credit crunch" stuff, here and tech section :lol:
is this a common problem with the 4 speed boxes?
cheers! :)

Re: Crunchy 4 speed(s)?

Posted: 09 Dec 2010 10:09 pm
by sven360
Have you checked the linkage for problems??

Re: Crunchy 4 speed(s)?

Posted: 10 Dec 2010 12:41 pm
by Ride_on
Normally the reason for crunching is a sticking clutch but that is more noticeable in 1st or 2nd. The synchro-mesh should stop the crunching so maybe it is worn out or broken off. Certainly not a normal problem, the gearboxes are the same in the 5 speeds, 5th gear is an additional box, and the design is originally from the 240. The gearbox are usually considered bom proof. I've broken an early diff once (pre-82), but all my exuberant driving has never yielded any gearbox problems in 340s or 360s.

If you have 2 cars with the same have you considered the common part they share..the driver? Try pushing the gear lever in more slowly, the synchro-mesh needs a short time to change the speed of the drive shaft. I usually find 2nd is a bit slow in these cars, 3rd less of a problem.

Re: Crunchy 4 speed(s)?

Posted: 10 Dec 2010 05:49 pm
by valman
Ride_on wrote:Normally the reason for crunching is a sticking clutch but that is more noticeable in 1st or 2nd. The synchro-mesh should stop the crunching so maybe it is worn out or broken off. Certainly not a normal problem, the gearboxes are the same in the 5 speeds, 5th gear is an additional box, and the design is originally from the 240. The gearbox are usually considered bom proof. I've broken an early diff once (pre-82), but all my exuberant driving has never yielded any gearbox problems in 340s or 360s.

If you have 2 cars with the same have you considered the common part they share..the driver? Try pushing the gear lever in more slowly, the synchro-mesh needs a short time to change the speed of the drive shaft. I usually find 2nd is a bit slow in these cars, 3rd less of a problem.
yeah even when giving it a good 10 second like coasting up to a round about, still crunches.. and i know what youre saying about the driver, but ive not had a single crunch with the 5 speed! and it is ONLY 3rd gear. on both a reg and e :/ it doesnt do it all the time, but quite often. how do i tell if the linkage is at fault? just usual things like bolts etc?
cheers!

Re: Crunchy 4 speed(s)?

Posted: 10 Dec 2010 06:57 pm
by Ride_on
Don't know how the linkage could be responsible, if you don't hit the gate it won't engage anyway. The linkage is just a longish (hollow) rod that can get bent, with a universal joint at both ends (I think). If that can be a problem, then gearbox/diff mountings (340 only) could also be a responsible.

On another thread we have learnt that the 5 speed main box is slightly different in that it has longer shafts, but otherwise I would expect the 3rd gear synchro/gate to be the same.

Re: Crunchy 4 speed(s)?

Posted: 10 Dec 2010 11:42 pm
by Speedy88
Just sounds like you've been unlucky to land with 2 worn boxes. I'm sure you could transplant the syncros from the 5 speed box if you're not using it?