Triumph Repair: Mk3 gearbox, s spline, hub assembly

Question
I have no problemen  putting the car in 1st 3nd or 4th
2nd gear grinds 4out of 5 times .The cover has since been removed and there is no visable ware onthe gears that can be seen
The only ware visable is on 1st and2nd slector fork legs

Answer
Hi Ken,

That tends to rule out the clutch as a problem and points to several possible causes. 2nd gear syncro ring receives the most ware in gearboxes due to the straight line shift from first.

The brass syncro ring's job is to get 2nd gear spinning at the same speed as the sliding hub assembly that is trying to engage it with when shifting into 2nd gear. Most people tend to make the 1st to 2nd shift too quickly, not allowing the gear and hub time to grab (syncros are cone shaped clutches)and that causes the splines to clash (the grinding you hear and feel)

However, there are other issues. Because the gear teeth are beveled there is a constant side load on each gear when under load. This wares the spacers between the gears and hubs. When a spacer wares too much the hub assembly has a hard time reaching the spline that it is trying to engage so it does not fully engage the gear's spline and thus it is kicked out and will not engage. (causing a grind)

The third issue that you have already noted is the shift fork. When a shift fork wares down it can not fully move the hub assembly far enough to engage it's gear.

My advice is to look in your manual for the side clearance of the hub assembly on the main shaft and use a feeler gauge to check it. If it is excessive, I would disassemble the gearbox and install new spacers, syncro rings and the worn shifter fork. While you have the main shaft apart closely examine with a magnifying glass, the splines of the 1st/2nd gear hub assembly and the 2nd gear splines for any sign of damage due to the gear clashing. If you are not familiar with what to look for, look at a hub and gear spline of one of the good gears (3rd or 4th).

If you have any problems let me know. Also, you should read my tech tip on how to make a straight stick gearbox last.  http:mg-tri-jag.net/tech4.htm

Howard