nc gearboxes

[bodge]

the lower case has dm on the right side the upper case has dm (as opposed to md) on the left hand case which i assumed meant it was an italian 5 speed but waiting for jon to get back on that.

i got a set of 4 speed clusters with the 4 speed cases but the output shaft is too tight in either of the bearings sprocket bearings in either of the cases no noticable differance on my calipers just wont go ?

[double diamond]

Have a look at this post: viewtopic.php?f=3&t=1703&p=12429#p12429
This will help you determine which type of 4-speed transmission you have (early or late). Since you apparently have both the early and late 4-speed cases you should be able to use the 4-speed transmission you have in the appropriate case once you determine which type of driven 1st gear you have. As far as the output shaft not fitting in the right side bearing, have you tried heating the cases to about 250 degrees F and freezing the shaft? If the ID of the bearing and the OD of the shaft are the same, you probably just need to use the heat/cool method and the shaft will fit with perhaps a light tap. Same with the input shaft if need be. Assembly lube on the shafts where they fit in the bearings would be good. Make sure everything is ready to assemble because it sounds like the shafts won’t come back out easily. Matt

[Rick]

I think you mentioned that some of the parts you bought were from a 175- there were 2(at least) different 4-speed ball bearing kick/first gear component sets- the early 175s had the parts at the left in this photo-

kick gears.jpg

Rick

[bodge]

thanks dd,nick, very informative kickstart post if ide come across that previously it would have saved me buying a 5 speed gearbox for my late 4 speed cases and a set of four speed cases as i thought i didnt have one,oh well stuff happens.
somewhere on this site i read 5 speed cases are identified by having dm on the left hand case,which it appears is only partially true hence my very expensive error.
im aware of the process of heating and cooling interferance fit parts bot isnt it unusual to have to do it for the inner race? my 5 speed output shaft fits with gentle persusion in either output bearing the 4 speed one doesnt at all just wondering if something else isnt going on tho i havent seen gearbox sprockets listed by model i assume all output shafts are the same ?
are early and late 4 speed boxes totally different or is it just the first speed driven gear and kickstart mech thats different?

[Rick]

I've never had it happen to me, but I've been told that if the clearance between the bore in the crankcase casting and the bearing OD is way out of spec, then the outer race can collapse on the balls, and the balls put pressure on the inner race, and the whole mess becomes distorted. Have you tried fitting your shaft to a new bearing- not installed in the crankcase?
Rick

[bodge]

not yet rick,just test assembling parts from various sources atmo but ill bear it in mind,may have to invest in a micrometer, i think it may be that the end of the shaft/one of the splines maybe fractionaly distorted do you know if the early and late 4 speeds are the same apart from the drven first gear?

[Rick]

I'm not sure if the other parts all interchange, but I'd suspect they do- Ducati changed the part numbering scheme in the catalogs, so the part numbers are different.
I have these transmissions- I'll find them and compare, but can't do it for a while.
I've found the 175s have the most parts that are unique to them- the 5-speed 250s are much easier to rebuild from a pile of Ebay parts.
And, I also thought all the 4-speed models had the DM250 stamp in the timing side case, so it appears that even the early 250s might be a problem when trying to interchange parts.
I hope that for you, like me, this is a hobby, and learning as you go is more enjoyable than frustrating.
Rick

[bodge]

thanks rick,atmo im finding it more frustrating than anything else tho im sure that will change when ive got one to ride,