11 replies to this topic

[spiguy]

Hi,

 

I was browsing some old posts, and found a thread discussing 3 / 4 synchro gearboxes. There were two things about that which made me wonder - firstly, I didn't realise there were two different types, are the later minis (I have a '92) all 4 synchro?

 

Secondly, something that Guessworks said :

 

 

The reverse gear in all mini gearboxes is also a crash gear, hence why you can't change into reverse while the car's moving, and is also a good indicator of clutch wear.

 

 

I wondered how the reverse gear could be used an indicator of clutch wear?

[Spider]

Minis when first manufactured in 59 were fitted with a 3 syncho box, the gearsets more or less came from the A30, though these were some differences. These were 'up-graded' over the years, then in 68-ish, the 4 syncho gearbox was introduced, though externally, they were similar in appearance to the 3 syncho. Then in 73-ish, the Rod Shift (4 synchro) gearbox came in to the range. This too has undergone a few changes over the years, the last major one being around 83-ish.

 

I'm guessing here what Guessworks is getting at is Reverse has no synchro, so if the clutch isn't releasing properly, it will tend to grind in to reverse.

[Guess-Works.com]

Pretty much so...

 

If the clutch is dragging then the gearbox 1st motion shaft and laygear will be rotating.. this means when the reverse idler is slid across by the selector, it'll try and engage with a rotating gear, which will mean either a clunk or a grind depending how badly the clutch is dragging.

[spiguy]

ah right. OK. Thanks for the explanation. That makes sense. I misunderstood a bit and thought it meant you could somehow determine clutch plate wear using reverse.

[nicklouse]

Nah you use the hand brake for that.

[spiguy]

Nah you use the hand brake for that.

Can you elaborate?

 

Thanks

[Guess-Works.com]

 

Nah you use the hand brake for that.

Can you elaborate?

 

Thanks

 

 

Half jokingly, but basically it's a stall test... put the handbrake on and try and pull away, you will soon get an idea of how the clutch is fairing, by the amount of slip and also the pedal travel to bite point.... Don't overheat the clutch as you will make matters worse...

[spiguy]

Thanks. What gear is best to use for this?

[Guess-Works.com]

Seriously ?

[spiguy]

don't laugh!  I have heard of the handbrake method before, but I'm sure the person who told me said to use 4th - ie handbrake on and let the clutch out quick, but in 4th gear.

[Guess-Works.com]

Just pull away as though you were doing a hill start, so bring the clutch up to the bite, that gives you where the bite is on the pedal travel, and then keep coming and the car should stall, or if you handbrake is not up to a suitable performance level, you'll pull away..

 

In general the higher the pedal the more worn the plate is.

[spiguy]

Thanks. I will give it a try. Of normal, ie if sitting with the engine on and in gear, I can let the pedal up and the car will start to crawl forward with the pedal release only about half way or slightly less, although of course this is only a light loading, so I guess the method above will be a better test.