1st motion shaft? issue

[5portsrock]

Hi ,
Im atempting to build up my remote change 4syncro CR gearbox but encountering an issue. All cr parts were good 2nd hand purchased individually.
Ive utilised the orginal gears and mainshaft from the box and added the cr laygear 22g1040 and a 18 tooth 1st motion shaft.
On fitting the laygear the box becomes very hard to turn over. The laygear is stamped 22g1040 so i know this is correct. Im suspicous of the 1st motion shaft primarily as if i replace it with a 17 tooth version the tightness goes away( im aware the mesh is incorrect for the laygear but trying to isolate whats causing the tightness).
The 1st motion shaft has 18 teeth and takes the 14mm bearing and has a 'S' stamped in it.
? Could this have the later A+ gear angles on it despite having the 14mm bearing ?
Any thoughts appreciated.

[Spider]

As far as I am aware, all the 18 tooth 1st motion helicals had the same tooth profile and helix angle. One way you can check for that is to remove the 1st Motion and the Laygear, then mesh them out of the box. If they are parallel, then there's a very high probability that they match.

The 'Input' Gear on this Laygear (22G1040) and the Std Ratio 22G927, have the same number of teeth (29), tooth profile and helix angle, the only difference between them being the diameter of this particular gear. The 22G927 'Input Gear' has a dia of 78.5 mm, measured over the tops of the teeth. If I get a little bit of time today, I'll measure the OD of the 22G1040.

[LuisM]

Can it be the input gear baulk ring "grabbing/sticking" onto your 18 teeth gear ?
was this happening with the pinion gear nut torqued all the way in? if not torqued up properly please do so and re-check.

Cheers
Luis

[Spider]

Of course, check as Luis has suggested.

If I get a little bit of time today, I'll measure the OD of the 22G1040.

The 22G1140 is 77.15 mm dia.

[Nick W]

when I built my c/r box ,the first I had done ,I spent hours puzzled why it was binding up .once torqued it was fine!

[rich@minispares.com]

id say luis is on the money

until both the large nuts are nipped up its impossible to check if the box is right

I tend to put the main kit in, drop the laygear in less its bearings, stick an old layshaft through it and lock the box in gears, then just nip the nuts, pull the laygear back out and then I can rotate the main kit and check it.

then, once im happy, I build the rest of the box.

[5portsrock]

Many thanks for the suggestions and measurements, much appreciated.
I shall re investigate at the weekend and report back.
Cheers.

[5portsrock]

Thanks for all the suggestions , parts measured and meshing checked. All ok

Refitted the mainshaft and laygear etc to the box. Torqued the retaining plate, 1st motion and pinion nuts. All spins beutifully.

Many thanks

[rich@minispares.com]

perfect result!

glad we were able to help!

[Spider]

Great result, thanks for letting us know how you went with it

[LuisM]

nice to know it worked, i had exactly the same trouble 1st time i did a gearbox!
After taking all apart 3 times.. i figured out he trick!

cheers
Luis