Shugmobile upgrade - Now with throttle linkage photos.

[tut]

80 mph in 5th at 4000 rpm is the S1 or equivalent C/R gearbox, ie 20mph per 1000rpm.

tut

[Shug]

Also just noticed in Mikes - straight cut (I assume quaife as well)

[Shug]

You know when you wish you'd never started something?

Gearbox is in the car and the car's running. I can only get 2 gears...

Now, I'd be the first to admit I'm a dick if I hadn't tested it and just slapped it in, but we had the thing all torqued up ready to go in on the bench and we were very careful to select all of the gears by hand and make sure it was all working. Slotted in and out of all gears like a well oiled rifle bolt and they all spun freely with hand pressure on the input shaft.

Now it's in the car and full of oil... nah. I'd say it had jumped selector forks if it wasn't sitting fine in the neutral position. You have to move it over to the 5th/reverse plane to get 5th and reverse (which work fine - it'll pull off in 5th, by the way) but it won't select third or fourth, and it won't move over the gate to the 1st second plane.

First thing you think of is the linkage, so disconnected that and I can't get 1,2,3 or 4 using the selector on the box itself - 5th and reverse go in fine.

Looking at my spare box, I've tried to work out what could have internally jumped to let this happen, but the way I see it, if the selector input shaft had slipped it's finger and yoke connection then it'd be jammed in the 5th/reverse plane. It's not. The really confusing bit is that it will sit in the 3rd/4th plane fine, but won't select 3rd or 4th.

I had to leave, as there was a gallon of petrol and a box of matches that was looking very tempting... Not sure I can face taking the f**king box off again.

[Mikie711]

It sounds like the linkage to me. Might have to reset the linkage from scratch. I take it your gear lever is in the middle and vertical when in neutral as described in the manual.
Might be worth checking that all the cable retention clips are in the right place and holding the cable securely. Next have a look at the bellcrank pivot bracket and make sure it's not bent out of shape, did this with mine when fitting a gear box one time. I take it you have checked that the bracket that is pinned onto the gear selection shaft is the right way up as is the pivot brackett and adjusted correctly IYSWIM. Try adjusting the bellcrank tie rods length as this is what gives you the cross gate action on the box itself.
To me, because you can select all the gears on the selector shaft the problem must be in the cable mechanism. Be interested to see the out come as I will soon face the same problem when fitting mine. I did have similar problem when I went to a CR box from standard.

Mike

edit: just a thought, you have got the cables the right way round at the gearbox, they cross over each other once they come out of the floor.

[Shug]

Ah, but mike, it's the same when I try and engage gears by hand at the gearbox input shaft - with all the linkages disconnected. That's the real odd thing. It works fine on the bench, bolt it on the car without changing anything and it won't work...

[Mikie711]

OK, must learn to read posts more carefully.

I had the same problem on the bench, for no apparent reason it wouldn't change gear. It turned out to be the syncro rings getting "stuck" and not being able to spin to line up with the little gear teeth on top/bottom of the gears. I took them out and swapped some around so they weren't so tight.
One thing to try to see if it is this is to try and select the gear and hold it in place to lock the syncro ring in place. Now try turning a drive shaft and in turn this may turn the shaft enough to release the stuck ring. However, if the stuck ring is on the input shaft you will need to turn the engine over while trying to select the gear.
This is really hard to explain in writting, Shug, PM me your phone number and I will give you a call if you like.

Mike

[robin]

Agree with Mike - the issue is likely to be the splines not meshing ... I assume you're pressing the clutch in? Ordinarily the gearbox oil is warm, the output shaft is spinning at current road speed and the input shaft continues to spin with rotational inertia/drag from release bearing/clutch still being between the pressure plate/flywheel. This means that the syncro has an easier job - it just needs to slow down or speed up the free shaft to match the speed of the driven shaft - when the speeds get close, the splines will engage.

If you're trying to engage gears direct from the control shaft (i.e. no leverage) with cold gearbox oil, engine stopped, and clutch engaged and the splines aren't coincidentally lined up, you need the splines to rotate to a position where they can engage - if you brake one wheel and then turn the driveshaft for the other wheel slowly you will rotate the output shaft and hopefully will line up the splines.

You can (possibly) feel the selector shaft in action - if you apply pressure to the selector shaft to put the box into 3rd then before it goes in the syncro will be braking the output shaft against the input shaft - you might be able to feel the extra effort required to rotate the driveshaft during this phase. You might need to give yourself a bit more leverage - either hook up the linkage and use the gearstick, or perhaps use a small screwdriver through the eye in the selector shaft (I think there's an eye in there!).

Cheers,
Robin

[Shug]

Will investigate this further - had a chat with Mike last night (cheers mate) and we came up with a method that might free up the synchro on the car. That said, in his box when this happened (still on the bench, before going in the car) the synchro was pretty well stuck, so needed popped off with a screwdriver under it - so it'd be unlikely I could get enough force to free it while the box is on the car.

I did try on the car spinning a driveshaft with the other side braked (really by accident, as I'd had one side apart to take off the wishbone, so the other side had binded up) So if it's this issue (which very much sounds like it is) then the synchro is most definitely stuck and will need freed somehow. I did actually run the car up and down the drive in 5th and reverse to see if I could get the internals spinning up to line things up as I felt it was something to do with alignment rather than anything jamming - as, like I said, it had worked fine on the bench (a few days before fitting it to the car - which could explain the synchro becoming stuck on)

I'll try freeing it up on the car, but it's looking like this box needs to come out again - hopefully it'll be a much easier job now that I've done it once...

[Cisco]

Shug,

Feel your pain,

I had something like that when I replaced a 911 box which was an engine out deal..couldn't get 2nd or 3rd I think..felt like burning the fng thing...anyway I took the selector linkage back out and played around with it..result, all gears slotted in fine..hope this little story gives you a ray of hope

Take care,

Frank

[Shug]

Promised some shots - so here's the throttle linkage:



and that's all yer getting as the rest were sh*t. Might modify the gearbox/chassis mount to make it easier to get off this time and show that - not much else of interest that can be taken without a third pair of hands on a camera, while it's all going back together.

[Shug]

Have a new technique offered to me by Craig at MMC that has solved exactly this issue before in other boxes (and involves no brute force and ignorance style efforts) Will give that a punt tonight first.

Cross everything please

[Rich H]

Will do but it's going to make driving hoe difficult!
Good luck matey!

[Shug]

Okay partial success - ran out of time (and jump leads to start it weren't there) Changed gearbox oil...

Basically, it involves swapping the gearbox oil out with 0W40 and then running it up to temp, teasing the gearstick in between the stuck gears and the combination of heat in the box (engine running while this is going on) thinner oil and the repeated pressure on the synchros eventually pops them. Supposedly it happens quite a lot in other boxes that sit on the bench for a couple of days for whatever reason before fitting. Can take some time to get it all freed up, but it is quicker than taking it all apart again.

So, going to sit in my parents driveway with the car idling and trying to get gears for an hour or so tonight - may take a book...

Craig swore this worked 95% of the time with similar situations on other 'boxes he's worked with, so I'm keen to give it a try (especially as it doesn't involve forcing anything or pulling it all apart again.)

[Rich H]

Slap a big magnet on the drain plug while you are there, will grab any ferrous swarf the box build may have liberated and the thin oil circulates. Hard disc magnets work well.

[Shug]

There's already a big chuffing magnet in the bottom of the box. Cleaned it up when I was rebuilding it (although it was almost totally clean - box had seen negligible miles since rebuild.)