Member Contributer vfrcapn Posted December 27, 2009 Member Contributer Share Posted December 27, 2009 Spoke too soon guys. The steering stem has a diameter of 32 mm on the bottom and 30 mm on top (where the tapered bearing goes). I have to assume that the stem is either tapered from 32 to 30 mm or that there is a ridge inside the lower triple clamp and the steering stem shaft has a 32 mm section up so far from the bottom and then steps down to 30 mm. That would make me believe that Honda assembles steering stems by pressing the stem into the lower triple clamp from the bottom, not from the top downward. BTW, here's a pic of the RC AL stem. You can just see the ridge on the bottom, I assume all the Honda AL stems are designed similarly with a step at the bottom. I don't think pressing the stem down 3mm would solve any clearance issues, if you have one, the race will still set flat against the lower triple. It's the relationship between the race and triple that counts, assuming you have a clearance issue similar to the RC parts. Link to comment Share on other sites More sharing options...
Guest Posted December 27, 2009 Share Posted December 27, 2009 Spoke too soon guys. The steering stem has a diameter of 32 mm on the bottom and 30 mm on top (where the tapered bearing goes). I have to assume that the stem is either tapered from 32 to 30 mm or that there is a ridge inside the lower triple clamp and the steering stem shaft has a 32 mm section up so far from the bottom and then steps down to 30 mm. That would make me believe that Honda assembles steering stems by pressing the stem into the lower triple clamp from the bottom, not from the top downward. BTW, here's a pic of the RC AL stem. You can just see the ridge on the bottom, I assume all the Honda AL stems are designed similarly with a step at the bottom. I don't think pressing the stem down 3mm would solve any clearance issues, if you have one, the race will still set flat against the lower triple. It's the relationship between the race and triple that counts, assuming you have a clearance issue similar to the RC parts. I agree that pressing this stem 3 mm further down will not solve my problem now that I see the stem pressed out of the lower triple clamp. However, now that I see this, this gives me another "work around". I have a 7" x 12" lathe. I couldn't mount the stem with the lower triple in my lathe. Now that I see that the stem can be pressed out, I can mount the stem portion only in my lathe, lower the lip that the upper inner bearing race sits on, and achieve my 3 mm drop distance. That I think would be the cleanest and most straight forward solution of all. Link to comment Share on other sites More sharing options...
SEBSPEED Posted December 27, 2009 Share Posted December 27, 2009 I agree that pressing this stem 3 mm further down will not solve my problem now that I see the stem pressed out of the lower triple clamp. However, now that I see this, this gives me another "work around". I have a 7" x 12" lathe. I couldn't mount the stem with the lower triple in my lathe. Now that I see that the stem can be pressed out, I can mount the stem portion only in my lathe, lower the lip that the upper inner bearing race sits on, and achieve my 3 mm drop distance. That I think would be the cleanest and most straight forward solution of all. Pete, I'm not sure what you're trying to accomplish by machining the stem. By moving the stem in relation to the triple, you're doing more harm than good because you are decreasing the area of engagement on the stem. Take a close look at VFRCapn's pic, do you see that dark line towards the bottom of the stem(right under the race seat)? That's actually a machined step of about .015"; the stem gets that much larger in diameter at the bottom, and this is the area that mates/interferes with the lower clamp. I have experience with this issue as I've swapped stems twice now in converting modern forks to early VFRs. Have you tried to fit the entire lower triple in your bike yet? The people that are having issues w/ the lower interference are the folks that are using a COMPLETE RC51 LOWER. It seems you've determined that you have a 929 lower + RC51 stem. The gives you a different ball of wax to work with! As I said, you really shouldn't change any of the stem values. Your first idea of machining a nice washer was a much more sound solution, as this would buy you any clearance you need while still keeping the press fit engagement of the stem intact and also keeping the dust seal against the frame. Just a note, before someone else brings it up, is that Honda did use a smaller area of engagement on some of the older CBRs(thinner lower clamp), however, in those cases, both the stem and clamp were made of steel! I recommend AGAINST separating the stem from the triple unless absolutely necessary! Link to comment Share on other sites More sharing options...
Guest Posted December 27, 2009 Share Posted December 27, 2009 Seb: I couldn't agree with you more. I do need to do a "dry run" so to speak before doing anything. Just trying to think ahead here. The portion I was talking about machining is the minute step about about 3/4" below the lower threaded area. The area where the upper bearing fits has an O.D. of 26.00 mm. The area right below the step has an O.D. of 26.15 mm. I think you're thinking I'm going to do the machining at the bottom of the stem. Not so. It would be in the area 64 mm from the top of the stem. The stem/lower triple clamp engagement amount would remain unchanged. Pete Link to comment Share on other sites More sharing options...
SEBSPEED Posted December 27, 2009 Share Posted December 27, 2009 Seb: I couldn't agree with you more. I do need to do a "dry run" so to speak before doing anything. Just trying to think ahead here. The portion I was talking about machining is the minute step about about 3/4" below the lower threaded area. The area where the upper bearing fits has an O.D. of 26.00 mm. The area right below the step has an O.D. of 26.15 mm. I think you're thinking I'm going to do the machining at the bottom of the stem. Not so. It would be in the area 64 mm from the top of the stem. The stem/lower triple clamp engagement amount would remain unchanged. Pete Ok, gotcha. That's gonna take some fancy setup work, but I'm sure it can be done. :fing02: Link to comment Share on other sites More sharing options...
Veefer800Canuck Posted December 28, 2009 Share Posted December 28, 2009 Have you compared the two steering stems side by side to check those dimensions? Perhaps you don't even need to remove any material? In my earlier post, I alluded to the fact that IF the entire stem were, in fact, further UP (3mm), then the top bearing MIGHT bottom out on that step, but I don't know if that is a fact or not. :fing02: If you were to measure/eyeball the two stems side by each, you could easily confirm if that is the case. In my case, with the RC51 triple, I was more concerned whether or not the top surface of the lower triple would rub on the bottom of the frame neck more than anything else. (due to the 14mm Vs 17mm bearing thickness) Link to comment Share on other sites More sharing options...
Guest Posted December 28, 2009 Share Posted December 28, 2009 Have you compared the two steering stems side by side to check those dimensions? Perhaps you don't even need to remove any material? In my earlier post, I alluded to the fact that IF the entire stem were, in fact, further UP (3mm), then the top bearing MIGHT bottom out on that step, but I don't know if that is a fact or not. :fing02: If you were to measure/eyeball the two stems side by each, you could easily confirm if that is the case. In my case, with the RC51 triple, I was more concerned whether or not the top surface of the lower triple would rub on the bottom of the frame neck more than anything else. (due to the 14mm Vs 17mm bearing thickness) No, I don't know for a fact that there is a difference. Just kinda planning a head. I have definitely decided I want to go the CBR929/954 stem route. I like the fact that the 929/954 uses the exact same tapered roller bearings as the VFR. I've just got to get everything apart and start doing some dimensioning. Whoever had my front end before just buggered up every single piece of hardware on the forks, stem, etc. Bolts in the wrong place, etc. I have said it before and I'll say it again, I think the key to making these inverted fork installations work is to get the triple clamps/steering stem correct. If I have to, I'll buy a new 929/954 stem. I've already got feelers out on the Fireblades website for one. I stated it must be in excellent condition. The only thing that keeps my sanity going about this project is that RC-51 forks are scarce as hen's teeth and I got the whole package at a good price. You would not believe what people are wanting for low mileage, good condition RC-51's. Link to comment Share on other sites More sharing options...
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