Selector mod

npaisnel · Post by **npaisnel** » Thu Jun 12, 2008 6:19 pm

[EDIT] Just found the correct name for the modified part in the PDF of the g/box manual. "Selector Rail Gates" are the part refered to, I have gone through and edited the posts to show this.

Here is a usefull mod if you ever need to have work on your gearbox. I had to rebuild mine, the top layshaft bearings had all collapsed and I need to re weld the corner where the gearstick plate bolts to.

Our local farm mechanic (retired) had a spare pair of new Selector Rail Gates, the bits that the ends of the gearstick sits in.

What the chap that gave them to me said, was that before fitting them back, weld some 'ears' to them. Use bolt heads that fit are 7/16th across the flats. Hold the shank of the bolt, weld the head on then cut the bolt off the head. Obviously you need 4, only 2 shown in picture.

Re welded corner, right had bolt in picture...donor cast material from scrap gearbox

You can just see the bolt heads, under the grease

Tmac · Post by **Tmac** » Fri Jun 13, 2008 2:11 am

What did you do about the sledge hammer hole in the bottom??

)

Post by **Oscar** » Fri Jun 13, 2008 5:54 am

Thanx for the photos

! What is the added value of the "ears"?

npaisnel · Post by **npaisnel** » Fri Jun 13, 2008 7:24 am

The one with the hole in the bottom was the one that donated bits of cast material to make the repair on this one. Also seem to remember it donating the odd gear wheel and selector fork.

The value of the added ears is to stop the bottom of the gearstick slipping out and jamming between the two gates. This used to often happen if the gearchange was not done with accuracy. I had also built up the end of the gearstick, but that has been done before many times in its life and this was never quite enough to totally cure the problem.

To un-jam the gearstick would mean removing te gear levers, putting the g/box in neutral with a screwdriver then replacing the gearlevers. A spanner for this was always carried, in our 'second' toolbox under the seat. (Extra seat supports welded either side of the main seat frame)

The repeated removal and replacing of the set screws was the cause of the damage to the corner of the housing. Years ago one of the staff overtightened/crossthreaded one bolt and cracked the corner off.

The gear lever getting jammed like this was a relatively common problem as they aged and the gearstick rounded out on the corners and the insided of the Selector Rail Gate edges became worn. Result; a straight gearlever movement became angled, and jammed the end of the gearstick between the two gates.

Post by **Oscar** » Sat Jun 14, 2008 8:19 am

All Dextas with a lot of hours on them suffer from this problem. Like you, I always used to carry some tools with me to avoid having to drive home in, say, reverse

. It's not immediately obvious to me how the ears solve the problem, but if it works then it works

. Looks like an easy mod to do, so thanx for sharing it with us!

npaisnel · Post by **npaisnel** » Sat Jun 14, 2008 8:58 am

Just done quick drawing in paint to try and explain it

The ears stop the end of the gearstick from slipping out the gap when the gates are not aligned when it is in gear[/url]

Post by **Oscar** » Sat Jun 14, 2008 12:21 pm

Ah, now I get it! That's very clever!

npaisnel · Post by **npaisnel** » Sat Jun 14, 2008 1:11 pm

Diagram often the best way....how much explaining would it have taken in text!