Gearbox synchroniser hubs

[miked]

Please see inside of new hub sleeve.
One side has parallel teeth. The other side has what looks like either wear or the form machined in that is a mirror of the dog teeth on a gear. I will try post other side next to try and get a good view. Bit hard with file size. When zooming and brightening I am stuggling with file size.
If you click on the photo you can see what i mean about the difference in the teeth each side. I can't expain it any better. It all implies that these have a correct direction of fitment.

My point is that I have some sychro sleeves that are perfectly parallel both sides. Show no wear or preformed shape. Direction does not come into it when you buy a complete hub with blocker bars and springs as the inner hub dictates fitment.
Cheers Mike

[miked]

Craven,

I have seen many in the past with etching marks but there seem to be lots with none. I spent ages looking for them on all the old bits of kit i have.

[2cams70]

See if you can get some close up pics. of what you are describing as "worn" and "unworn". See if you can get a picture too of the corresponding dog teeth on the straight cut gear the hub is mating with. Can you set the camera on minimum resolution before taking the pic.?

[miked]

Thanks for reply, left home until Monday. Will pick up again.
The straight cut example is well gone. Cured with new full hub. I binned the old hub for the grief it caused me. Was sat on shelf fir two years, pity. I was just mentioning that to make a point.
Still i have examples of many worn ones.
What do you think of the new hub sleeve photo with different sides and my point about fitting one way around or the other.
Cheers Mike

[2cams70]

So you want to confirm which way around the 3/4 synchro sleeve should be fitted given that the internal splines are not symmetrical around the centre? I'll have a dig around and see what I can find but unfortunately it's been a while since I've rebuilt a gearbox and memory fails me somewhat. When I rebuilt my 2000E box many years ago I did it by combining all the best bits from 2 boxes. One box was the later single rail type out of a 1600GT Ford Capri I found at the wreckers (oh the joys you could find in wrecker's yards back then!!). It had excellent condition later type hubs that I swapped over into the 2000E box.

[joe7]

The last picture shows the incorrect way to fit the hub. The drill mark goes to the rear. On later type hubs without the drill mark the way to tell is that the hub has a "ridge" where 3rd engages, also the same on the hubs with the drill mark. The 4th gear side does not. Also if you compare the location of the shift fork "groove" with the hub installed correct VS incorrect you will note that there's about .050 difference, which if installed incorrectly maybe why its jumping out of gear. Also you should be sure that the 3rd gear stop tube is installed and has the correct specs of zero when 3rd gear is engaged. In some cases early model don't have the tube, later models have the tube but the clearance is incorrect and requires a washer (see manual) next up has a tube but uses a clip to obtain the zero clearance and finally the late models have the correct length tube.

[Craven]

This is a later type Mk1 Mexico box 1/ 2 hub, clearly machined differently. Unfortunately don?t have a good front hub.

[2cams70]

Unfortunately I don't have any gearbox bits around to lay my hand on at the moment. I suspect the coupling dog ends are different either side of the sleeve because the synchro rings are different either side of the sleeve. When the rings are initially pushed forward onto the corresponding gear cones during gear engagement due to the friction they rotate slightly relative to the 3 blocker bars. This puts the dogs on the synchro ring out of alignment with the dogs on the synchro hub so gear meshing is prevented. The shape of the dogs in the hub are designed such that the dogs on synchro hub and synchro ring are out of alignment under these conditions. As the speed of the hub and the gear being engaged synchronize (the friction acting between the synchro ring and the cone of the gear being engaged does this) the ring becomes free to float slightly around the blocker bars. Under these conditions the 3 sets of dogs (on synchro hub / on synchro ring / on gear being engaged) come into line and so the hub becomes free to slide forward and lock onto the gear being engaged.
All very hard to describe in words but I expect if you have all the bits in your hand and place them together with some imagination you'll see how it works. Incorrect synchroniser assembly is more likely to result in gear clashing than jumping out of gear. Jumping out of gear is more likely to result from wear or incorrect manufacture of parts.

[normanjsmith]

Back in the late 60's I replaced synchro rings, bearings and layshaft in my c/r gearbox. Unfortunately, it jumped out of third gear. The problem was that the outer hub was around the wrong way, As Joe says, the drill mark should face rearwards.

[2cams70]

Ok point taken. The sides of the dog teeth are probably different angles either side of the hub then and not just straight. That's the only way a lateral force could be imparted on the sleeve under load pushing it off the gear. I don't have any bits to look at at the moment unfortunately.

[Greg Foster]

IN NO WAY do I have expertise in this area.....but.....my 2 cents for what it's worth....did you check the dimension of the detent springs as per the manual? Just a dumb thought.

[Craven]

Superficially these gearboxes look the same, but when it comes to replacement parts or like many laymen that have thought they could swop this good looking part from another box, they are a minefield.
There have been many design changes over the +20 years of production some major like the change in helical gear angle, most have been to address gear selection rather than power handling capabilities.
These points have been covered on this forum before but here are a couple of examples.
1. How the synchro rings have been strengthened and change in dog tooth pattern, requiring the correct syncho hub.
2. Changes in the detent size on selector rods, requiring ball spring shim to improve selector fork stability.
There are many more, improved rear main bearing oil supply, blocker bar changes and so on, any amateur, and I include myself here, who mix and match parts could quite easily inadvertently build in problems.
FWIW

[miked]

Apologises for late reply, just got back.
Thanks guys for the help. Yes, i am an amateur but always willing to dig in and learn.
Also not frightened to ask questions if i dont understand. Also if i have made a mistake, happy to own up.
The answer you gave, Joe, answers exactly what i was after. The drill mark and the line cut in on the later hub. I see what you mean about the hub example on the photo being put together wrong. I have measured those rail stop tubes in the past and seen the different type and the circlip that makes up the short one. To ensure correct stop I have selected 3rd gear and watched the detent groove to ensure the stop centres it.
Looks like I made my own problem with the straight cut example.
Interesting about the 50 thou offset, i was trying to measure it and see now what you mean about it setting the position correctly
As regards the detent springs, i have seen shims and made my own many times as even the new ones are not as long as the books specifies. I have punched out 60 thou alloy ones. Whilst they give a snicky positive click of engagement, when i did the straight cut one wrong it was a actully driving out of gear under power with my hand pushing on the solid lever. No detent spring or ball would have held it. My error.
I have spares of the early and late synchro ring and hubs, different blocker bars and the rear bearing carriers with improved oil ways etc
Thanks for the help.

Cheers Mike