Later USD triple trees on 89/90 frame

discussion about the 750 Sport and '89/'90 900SS, which share many mechanicals with the Paso series
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bbeen71
Posts: 28
Joined: Tue Jan 21, 2020 2:18 pm
model: 900 SS
year: 1990
Location: Norway

Later USD triple trees on 89/90 frame

Post by bbeen71 »

I am fitting the triple trees from the later 900SS on my 89 and was adviced to use the 32005/26 bearings for the swap. They do indeed work, but the bottom bearing seems to recess further into the frame than the old bearing so the lower crown is hitting the frame. Has anybody else had this problem and how did You solve it. Additional spacer under bearing cup in frame or a spacer on the triple tree, or a bit of both?
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Bearing too far in so will not be able to get any preload on the bearing
Bearing too far in so will not be able to get any preload on the bearing
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ir_joep
Posts: 106
Joined: Sun Jul 26, 2009 7:35 pm
model: 750 Sport
year: 1989
Location: Haarlem, The Netherlands

Re: Later USD triple trees on 89/90 frame

Post by ir_joep »

Hi,

Currently I’m doing the same. I’m using the original stem pressed in the USD triple tree. That should allow the original bearings and spacers to be used. Not sure if the steering bumpers need to be removed/filed off.

Assembly is planned as the new bearings arrive somewhere next week.

Cheers Joep
bbeen71
Posts: 28
Joined: Tue Jan 21, 2020 2:18 pm
model: 900 SS
year: 1990
Location: Norway

Re: Later USD triple trees on 89/90 frame

Post by bbeen71 »

With the 32005/26 bearings the USD stem for fine in the frame. But will have to sort out the height of the lower bearings.
Speedmade
Posts: 49
Joined: Sun Jul 12, 2009 1:56 am
model: 906 Paso
year: 1989
Location: Minnesota, USA

Re: Later USD triple trees on 89/90 frame

Post by Speedmade »

I put a spacer under the lower race when I put a set of Showa forks from a 1995 900SS on a Sport
bbeen71
Posts: 28
Joined: Tue Jan 21, 2020 2:18 pm
model: 900 SS
year: 1990
Location: Norway

Re: Later USD triple trees on 89/90 frame

Post by bbeen71 »

Speedmade wrote:I put a spacer under the lower race when I put a set of Showa forks from a 1995 900SS on a Sport
To be sure; that means You put the spacer in the frame under the bearing race?
User avatar
ir_joep
Posts: 106
Joined: Sun Jul 26, 2009 7:35 pm
model: 750 Sport
year: 1989
Location: Haarlem, The Netherlands

Re: Later USD triple trees on 89/90 frame

Post by ir_joep »

If you use the original stem which matches the steering head, the location of the bearing part on the stem matches the locations of the bearing part in the steering head. That is of course if you use the original spacers.

I did try to use the later USD stem but could not get it it work. I tried spacers under the bearings in the steering head but ended up with the bearings not fully matching the machined parts of the stem where the bearing should sit. I felt that that was unsafe. It seems that the bearing location on a later USD stem are further apart then on the original stem, which are spaced closer.

I hope this helps.

KR Joep
bbeen71
Posts: 28
Joined: Tue Jan 21, 2020 2:18 pm
model: 900 SS
year: 1990
Location: Norway

Re: Later USD triple trees on 89/90 frame

Post by bbeen71 »

That makes sense. I am thinking about making some spacers underneath the bearing races in the frame and pushing them further apart. This will also move the lower crown down which I also need. If this doesnt work using the later stem is the next course of action I think ;)
Thanks
bbeen71
Posts: 28
Joined: Tue Jan 21, 2020 2:18 pm
model: 900 SS
year: 1990
Location: Norway

Re: Later USD triple trees on 89/90 frame

Post by bbeen71 »

Well, then its on. I ended up using the stem from the 91-97. I made a spacer under the bearing race on the stem (same height as the original). I also made spacers underneath the races in the frame and discarded the original ones. 5mm if I remember correctly. Had to grind away the sterring stops as they hit the lower frame rails. Only problem now is that the fork legs hit the upper frame rails and the steering stops in the frame doesnt hit the lower crown. I will get the lower crown welded so the it will hit before the fork legs touch the frame. Also fitted the front wheel after adapting the spacers. Waiting for calipers to see what I need to fo to make room for the discs :)
Pictures when I will find energy for tiresome resizing of pictures..
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