Type 9 5 speed box - Speedo and getting jammed in 3rd

[Toby S]

Hi All

I've got 2 problems which have developed over the last month or so and want to check if they are possibly linked;-

1. Speedometer, which runs off the gearbox (1992 Supersport with type 9 5 speed), has started to waver up by circa 5-6 mph at up  to 60 mph and then holds steady once above this speed
2. Following this, a few weeks later (last weekend and again this weekend whilst on reasonably long blats - 50-100+miles) I've had 2 or 3 occasions where the box has jammed in 3rd at fairly high revs  when I'm going for a change up to 4th. Engine seems to be fully disengaging with the clutch action, and once I've scrubbed off enough speed and the engine revs have dropped a bit and I've dipped dipped the clutch a few times again, I have be able to change gear both up and down as normal and proceed as normal

I've managed to get under the car to a certain extent this evening (although only high enough through trolley jack and axle stands and I'm no slim Jim) and felt the speedo cable and angle drive which don't seem that tight into the gearbox (can certainly wiggle them around a bit), but whilst doing this noticed it seemed pretty oily around the gearbox and angel drive and cable.

I was wondering whether it may be possible that the angle drive for the speedometer has managed to get dislodged and lose an oil seal or something and I have lost oil, and the gear jamming problem is resulting from resultant low oil levels in the gearbox.

Planning to get it up on the ramps of a friendly garage so I can get it high in the air to have a proper look, but thought in advance I check on your collective knowledge gentlemen whether I'm may be on the right track or whether its more likely they aren't linked and something more sinister is causing the gear jamming.

P.S. Thrust bearing on the clutch has always been a bit noisy/rattlely when foot off the clutch - I've never been that comfortable with it, although its done more than 12,000 miles like that and I've had no engagement or disengagement or indeed clutch slip problems and that's still the case

Thanks for any thoughts in advance

 

[7 wonders of the world]

speedo is driven from a gear on th mainshaft, oil leakage is common form this area as the tiny seal get a hard life.

Is your speedo  cale drive or eletronic sensor and wires..?  

Selectors are in the maincase of the box, 3rd is pretty common for syncro breakages especially on std ration boxes as when driven hard they get a very hard time, higher mileage boxes can suffer form worn hubs too, and worn blocker bars and ans hub springs are not uncommon.

The rattle noise your hearing with the engine running ns foot off the clutch is most likely to be the laygear chattering - once the clutch is depressed the drive thro the box ceases and all goes quiet, again under drive conditions also as the gears are loaded.

Steve @ SPC in Redditch is the place to take the box if needed might even be a good oppertunity to upgrade to some better ratios... 

[Wrightpayne]

The speedo drive often weeps a little and attracts road detritus so can look messy. If its not dripping then I wouldn't worry. The drive is only held in with a circlip so will move around. Just check the collar on the cable holding it to the angle drive is hand tight and same for the angle drive onto the brass 'top hat' fitting that is held in the gearbox by the circlip.

I seem to remember reading that the speedo drive gear on the output shaft of the gearbox can come loose/move though would expect more that a momentary needle wobble! 

[Jonathan Kay]

You can improve access to the speedometer drive and the oil seal by loosening the engine and gearbox mounts and yanking the tail of the gearbox to the side.

If it's a mechanical cable drive you might be able to localise the fault by disconnecting the cable from the gearbox drive adapter and spinning the inner cable with an electric drill.

Jonathan

[Toby S]

Cheers guys

Yes its a cable drive speedo (VDO speedometer) not electronic - I'll get it up in the air and take a better look

Good idea re speedo Jonathan

[blueyedbiker]

Possibly the first sign that the cable is on its last legs.

[Alastair B]

+1 for cable on the way out, mine did the same

[ECR]

My (frequent) experience is that the third gear synchro ring breaks but stays in place. This makes selecting third gear difficult. After a while the synchro ring becomes dislodged and then you either can't get it into gear or it gets stuck In third. In any event, it's box out and a rebuild I'm afraid. I broke a few rings (track use) and it's the reason that I run a dog box now (no synchro rings)