Single rail pull down

[LJDB 103]

how difficult is a single rail to strip down. Mine recently developed a noise at idle so I swapped it out for a spare I had laying around, only to find the spare one crunches 2nd on down shift. Would it be difficult to strip the 2 and use the good parts or better off buying another good one?

[gerg 10,871]

They're a pretty simple box. You do need to pay attention to how the layshaft goes in/out, I think there's a small taper to it so one way in and out (can't remember which way). Also the needle rollers need to be arranged neatly and held in place with grease. May need a press to get bearings off.

 

Syncro on second is very common due to the driver revving it out in 1st and slamming it into 2nd all the time. Worst on wide ratio boxes with big rpm differences between gears, works the syncro harder.

 

What exactly was the noise at idle? If it's just gear chatter then that's harmless. If it bothers you too much go with a thicker oil.

[LJDB 103]

it developed a noise at idle after a good thrashing and got worse the hotter it gets. I pulled it down and change the input shaft/bearing over from one to another and checked it over. The bearing was noisy so i just changed the shaft over. It took me a couple goes to get it all back in, first i put the lay shaft in first and couldnt get the input shaft back in. Then 1 input shaft roller fell in so i had to pull it all back out. The syncros looked goo in both boxes. What should i look for in a worn syncro?

[gerg 10,871]

The syncro clutch (cone) should still have grooves in it for oil release, if worn this would give slow/baulky shifts. It could also give crunchy shifts due to insufficient clutch bite for the baulk teeth to work.

 

The baulk ring teeth themselves should have a nice taper either side of each tooth, coming to a point on the front of the tooth where it meets the shift collar. This taper both guides it in and also holds it out of engagement until the dog and shift collar are spinning together. If the baulk teeth are excessively worn, they'll have this taper flattened off, causing difficult or crunchy shifts.

[Trevor 326]

Generally 2nd gear is dodgy because it is generally your 'cornering' gear, and people pull them back into 2nd at a speed too high (using the gearbox them as a brake, to "slow them down") and thus wearing the synchro's overly

 

You see exactly the same thing in truck synchro gearboxes, generally it is 4th in them

[gerg 10,871]

Yeah in trucks these days they get anyone behind the wheel with a HV licence and they drive it like it's their wife's Hyundai. You can tell the ones who learnt on road rangers, the syncros are still there after 500,000 km.

[Trevor 326]

all too quickly people blame the gearbox, but nearly all issues with transmissions are caused by the operator not driving them appropriately. pushing them beyond what they are designed to do

[Trevor 326]

We have run a single rail in our XE track car for over 7 years, other than a rear seal it has given us no problem

[deankxf 20,288]

My Dad machined down the shifter shaft(one in the shift housing) a d made new brass bushes and that made a massive difference to the shift feel(along with new horseshoe bush)
it wouldn't surprise me if this wear causes the selector seal to get chewed out..

anyone with a single rail should check if it has oil in it and if not, change the selector seal, when i got several of My cars with single rails, they had no oil. and topping them up lasted 500km max before they were empty again due to that seal. (they work surprisingly well with no oil)

[gerg 10,871]

Mine had the brass plug fall out the back of the shifter housing, and dirt and shit got in and wore it out. Had to weld some metal back on the knuckle and grind to shape. I just ran grease in it after that. Worked better than factory! One thing that is hard to fix is the reverse detent bar (the one that makes you push down to engage). If this wears out you can accidentally grab reverse on the move.

[deankxf 20,288]

Mine had the brass plug fall out the back of the shifter housing, and dirt and shit got in and wore it out. Had to weld some metal back on the knuckle and grind to shape. I just ran grease in it after that. Worked better than factory! One thing that is hard to fix is the reverse detent bar (the one that makes you push down to engage). If this wears out you can accidentally grab reverse on the move.

that reverse issue is why mine needed re bushing in the housing now i think about it. was all good after that. and reverse lights coming on during gear changes and not in reverse etc.(i have filed the reverse switch face down in the past to get them to work also)(so it screws in a fraction further)

one of mine also had the welsh plug at the back missing, i wonder if this was the one(it had the best thread for the stick of all i had anyway is why i used it)

 

[gerg 10,871]

Lol on a cortina you can move it over into the reverse gate but not into gear, and bring the lights on while driving. If you have a dickhead tailgating, you can flash behind with your reverse lights.

 

Done the reverse switch trick too like you did, but on a Transit at work, and on a lathe. The shaft and ball wear out so it trips too early. Machining the switch face brings them further into engagement.