I'll be the 3205 guinea pig (Tonti 5 Speed Transmission )

[acogoff]

     I've decided to run these Austrian mfg 3205a c3 explorer skfs with the 9 balls per side just for grins in the T3. They have a retainer that is magnetic so I assume it is steel.  Also I measured up the end float that the old Main shaft(cluster) had with the worn falling out rollers thrust bearing and came up with .009 inch without the gasket. When the new thruster gets here I will attempt to maintain that .009 clearance. I have been unable to find any spec on this except for an overall length of the older 5 speed that I think have have the bushing instead of the bearing.
Does anyone have any thoughts on this main shaft clearance.



uploadphotos
 

[ITSec]

I have no thoughts on this, except that (unless one has context) this is probably the most confusing stream of gabble I have recently seen! 

[Tom]

 :1:  The OP user name is "ACOGOFF".    I surmise that it's trans. related but after that "Y'all gots me???"

[Testarossa]

SKF makes high-quality roller bearings.  I believe the post is about using an aftermarket bearing in a T3 transmission instead of the Guzzi OEM part.

[fotoguzzi]

[ITSec]

By the way, my intent was not to be unhelpful, but to note that the OP had offered what was a superb example of something that was extremely intelligent (if one had the context) and extremely confusing (if one did not). The photo helped a lot once I had opened the thread... 

[acogoff]

    Sorry,Guys, Yes, I was not clear what I was working on. The fog of age, maybe. It is a transmission off my 1977 850T3 that had broken the shifter spring and is being freshened up with new bearings, etc. as long as it is apart. The last part of my question is if any one knows how much end clearance is there supposed to be on the mainshaft (the middle one with all the fixed gears on it).  That spec is seems elusive. I know it has to move about a bit as it operates. 

[Orange Guzzi]

Somewhere I read that if the shaft moves forward and aft, it is too loose, if it will not rotate, it is too tight, if it will rotate and not move forward and aft, it is just right.  Do this by installing the shaft with other gear shaft and output shaft out and finger inserted into the output shaft hole.  Stack shims on shaft as needed.  You will need a selection of various thicknesses to mix together to get the right clearance.  I would do it with the gasket in place and a few screws installed and snug. 

[Tom]

Okay, my brain cells needed a little prompting.    You have a broken shift return spring and the bearings are loose.  So upgrading the bearings will help with making the shift spring last longer?  IIRC the replacement shift springs that are now available are made with better steel.  Anyone can correct.

[jvb]

"It is a transmission off my 1977 850T3 that had broken the shifter spring and is being freshened up with new bearings, etc. as long as it is apart"

Checking and replacing the bearings (as required) while the transmission is apart to replace the spring. I don't see any reference to loose/worn bearings being the cause of the breakage.

I think that's it anyway.

John

[n3303j]

The '60s BMWS used 0.000" +0.002" - 0.000" end play as their specifications for properly installed transmission shafts.

[acogoff]

The '60s BMWS used 0.000" +0.002" - 0.000" end play as their specifications for properly installed transmission shafts.

     Now we are getting some where. Between you and Orange Guzzi's feedback, at least now I have an idea that it should be a little tighter than it was. The old gasket that came off intact measures .005 + the slop I measured would put the end float at about .014-.015. A bit much, it seems.  It looks like the UPS man will be bringing me a few boxes of shims until I can get it to the not quite zero range. Thanks Guys.

[kidneb]

     Now we are getting some where. Between you and Orange Guzzi's feedback, at least now I have an idea that it should be a little tighter than it was. The old gasket that came off intact measures .005 + the slop I measured would put the end float at about .014-.015. A bit much, it seems.  It looks like the UPS man will be bringing me a few boxes of shims until I can get it to the not quite zero range. Thanks Guys.

That`s where you want it !
Last 5 speed I did was a helically cut one for my own bike after giving up on a failing straight cut one, and I did focus on the mainshaft end float to try minimise the for and aft movement.
I always use an used gasket when I`m shimming up a gearbox.
I think it was a 2,2mm support washer/shim I put in and found the shaft rotating quite freely, but with absolutely zero end play. I was a little nervous about leaving it that tight, as you dont want to put pressure on the ball bearing. I had a colleague with a magnetic table grinder (or what it`s called) shave off just a couple of hundred mm or so, just so I could feel a little end play.
That, together with shimming the drum, made for a very nice shifting gearbox. I was a little nervous about ending up with that infamous clunky stuff that people talk about, since it was the first time the LM3 was being equipped wth a helical one. But I was pleasantly surprised, it shifts very well, just as smooth as the straight cut boxes that I`ve been running. No clunk, nothing, and the neutrals between the gears are my friends.
I do miss the close ratios though, but that`s another story.

[acogoff]

     Thanks for the input Kidneb. Your reply confirms what the last two posters were talking about. And the fact that you have actually went through this with a good result is very encouraging.  As soon as the new thrust bearing arrives so I can see what actual thicknesses I am dealing with I can have at it.

[TOMB]

I thing that somewhere on this forum Pete Roper had a complete rebuild with pictures and clearances .
TOMB