Topic: Swapped forks/triple clamps, now it "feels funny"

[MJL]

I swapped in a '75 Goldwing front.  I left the 750 races in the head, and the GW races on the stem. Cleaned the races and ball bearings, new grease. GW disks and bolts went on the 750 wheel, along with the GW speedo drive.  Everything bolted right up. I used new low rise bars and the 750 gauges, plus rewired for the GW idiot lights to work with the 750.  The rest of the bike is stock, tires are Dunlop 404s.

Now, it feels like the bike wants to fall over, like it won't go straight on it's own. I checked alignment with the front wheel and I believe it's as close as I can get it. It rode fine before. I then slid the tubes up the clamps first a half inch, then a full inch. It seems to have helped a bit, maybe half as bad as before.

I spent some time searching, but I didn't find anything on this topic. Maybe my search skills suck today.

Is there anything I should check to make it ride better, or is it a case of bad geometry due to the different offset in the triples? I did set the bearings up on the tight side, perhaps I should loosen them a bit and see if that helps?

[eurban]

It is pretty much a no no to mix bearings and races.  I doubt you will ever get satisfactory results with 30+ year old ball bearings installed in a mix set of races.  Get yourself a new set of tapered roller bearings, install and adjust them properly, and I would bet your problem goes away.  My 78750K has a gl1000 front on it with the forks flush at the top of the trees.  Steering is perhaps a bit slower with the longer forks but the bike is dead stable. 

[fishhead]

It is pretty much a no no to mix bearings and races.  I doubt you will ever get satisfactory results with 30+ year old ball bearings installed in a mix set of races. Get yourself a new set of tapered roller bearings, install and adjust them properly, and I would bet your problem goes away.   My 78750K has a gl1000 front on it with the forks flush at the top of the trees.  Steering is perhaps a bit slower with the longer forks but the bike is dead stable. 

 +1 on the tapered bearing set.

 My 74 CB 750 with a 75 GL 1000 front end is dead stable also.

[MJL]

Thanks, I was planning on tapered bearings anyway, I just wanted to have it rideable. Will look for a parts supplier.

[Alan F.]

www.chaparralmotorsports.com has good service, and decent prices on the all-balls kits.

[mystic_1]

How much difference in the offset of the trees?  Changing offset definitely affects trail.  Know how to measure the actual trail of hte front end?  I'd do that, in addition to the new bearings.

mystic_1

[MJL]

Good question. It is noticeable, I'd say quite a bit. I'll measure the 750 top clamp and check the GL top clamp, I should have an answer tomorrow. 

[Bodi]

Changing the offset has a serious effect on handling. The offset has to work with the rake angle and the effective trail of the wheel to get fairly neutral steering: not falling into turns but not needing to be pushed hard to turn. SInce your rake will be the same and the trail is probably very close (same diameter wheel and the axles are both roughly in the middle of the fork tube) the offset must be different. This is why you'll often see instructions for using oddball combinations of fork tubes and triple trees for front end changes. The 400F likes CB450 triples as I recall, the offset is the same.

[MJL]

Just as an update, for anyone searching, the problem must have been in my fork bearings, because I installed a set of tapered bearings and the problem went away.

[mystic_1]

Excellent, glad you got that sorted.

mystic_1