Jump to content

Cbr 954 upper. Fitment?


Bren

Recommended Posts

  • Member Contributer

I´ve started my SP1 conversion and have come across a rather odd thing.

gallery_12476_5185_305426.jpg

Cbr 954 Upper - Fitted

gallery_12476_5185_513276.jpg

CBR 954 Upper. 2.5mm difference.

At first I thought the worst. F%&k the forks are bent!! Then, the triples are bent! But no all is straight and proper. This I found out after I took it all apart checked everything and then put on the SP1 upper I have.

gallery_12476_5185_567463.jpg

SP1 & CBR Uppers

Here is the SP1 upper installed just to check that everything is fine.

Then I measure everything and there is a 2.5mm difference between the fork clamps and the steering stem hole of the two uppers.

I say odd because I´ve never heard this mentioned by anyone who has done the conversion before.

So is this a known issue and if so what did you do? The only remedy I can see would be to grind 3mm away from the front of the Upper´s steering stem hole to allow the stem to pass through. This I am thinking would not cause any structural problems as the upper is not fixed as such to the stem, only tightened down around it, its not an interference fit. Plus asthetically it will be covered by the top nut so wont be seen.

Anyone who´s done the swop care to chime in?

Bren

Edited by Bren
Link to comment
Share on other sites

  • Replies 84
  • Created
  • Last Reply

Top Posters In This Topic

Well, I hate to tell you, but something IS bent. The offset is the same for 929/954/RC51/CBR1000RR(04-06).

Does the RC51 clamp slip right on, or is there some resistance? Meaning, can you lightly push it into place, or do you have to lean on it/tap it on?

Link to comment
Share on other sites

Also, I don't know what the offset for the CBR600RR is, but that would seem irrelevant - your triple obviously has the older Honda emblem, so it must be a 929/954 clamp.

Try taking the clamp off, and placing it right side up on a piece of plate glass(or hold it against a window) and check it for straightness. The 2 clamp areas should sit perfectly flat, and the mounting area where the stem passes through should be perfectly parallel to them.

Link to comment
Share on other sites

  • Member Contributer

The SP1 upper slides on. I mean slides, no banging or swearing involved.

I´ve measured it Seb. There is a difference of 2.5mm between the two uppers, fork clamp to steering stem hole.

Thanks for the reply though.

Bren

Link to comment
Share on other sites

The SP1 upper slides on. I mean slides, no banging or swearing involved.

I´ve measured it Seb. There is a difference of 2.5mm between the two uppers, fork clamp to steering stem hole.

Thanks for the reply though.

Bren

I would still like to know if it's flat or not. Hard to tell from your pics.

Link to comment
Share on other sites

  • Member Contributer

I would still like to know if it's flat or not. Hard to tell from your pics.

I´m not near the bike again till probably next week but I´ll definetely try what you suggested. As I said seems funny to me as no-one has ever mentioned it before.

I did paint the triple but masked off the fork clamping surface on the upper itself, so no paint can skew the angles etc. Good thinking though :fing02:

Edited by Bren
Link to comment
Share on other sites

Just out of curiosity, did you paint the triple, or did you get it that way?

I can't think of any other US bikes from that era that got that gullwing triple, the only ones I know of have the same offset. But, being in Europe, you might be dealing with something we don't know about? Doubtful, but there's a chance I guess?

Link to comment
Share on other sites

  • Member Contributer

Just out of curiosity, did you paint the triple, or did you get it that way?

I can't think of any other US bikes from that era that got that gullwing triple, the only ones I know of have the same offset. But, being in Europe, you might be dealing with something we don't know about? Doubtful, but there's a chance I guess?

I suppose everything is possible, but....I did buy it as a 954 upper. Ebay so that of course means it could be anything

You might be onto something if the upper is flat or not. I´ll have to check that out. Thought maybe this was something that got left out of the previous build up reports.

I did paint the triple but masked off the fork clamping surface on the upper itself, so no paint can skew the angles etc. Good thinking though

Edited by Bren
Link to comment
Share on other sites

I suppose everything is possible, but....I did buy it as a 954 upper. Ebay so that of course means it could be anything

You might be onto something if the upper is flat or not. I´ll have to check that out. Thought maybe this was something that got left out of the previous build up reports.

I did paint the triple but masked off the fork clamping surface on the upper itself, so no paint can skew the angles etc. Good thinking though

Of the many swaps that have been done, at least one person would have commented on having to grind the triple by now. That would discount the entire mod, IMO, it's just not sound or a good idea at all. I've done some of these swaps and I know that the triple should slide right on.

BTW, which lower triple are you using?

Link to comment
Share on other sites

  • Member Contributer

I suppose everything is possible, but....I did buy it as a 954 upper. Ebay so that of course means it could be anything

You might be onto something if the upper is flat or not. I´ll have to check that out. Thought maybe this was something that got left out of the previous build up reports.

I did paint the triple but masked off the fork clamping surface on the upper itself, so no paint can skew the angles etc. Good thinking though

Of the many swaps that have been done, at least one person would have commented on having to grind the triple by now. That would discount the entire mod, IMO, it's just not sound or a good idea at all. I've done some of these swaps and I know that the triple should slide right on.

BTW, which lower triple are you using?

Lower is SP1. The SP1 upper slides nicely on. Strange

Link to comment
Share on other sites

  • Member Contributer

I think the answer is clear - use a matched triple clamp set. I've not seen anyone try to use an RC51 lower with a CBR upper as you are trying to do. What is the purpose for this?

Link to comment
Share on other sites

  • Member Contributer

Well after further research the rake and trail of both bikes is different.

Honda RC51/SP1

Rake: (Caster Angle) 24.5 degrees

Trail: 100.5mm (3.96 inches)

Honda CBR954

Rake (Caster Angle): 23.45°

Trail: 97mm (3.8 inches)

Honda CBR 929

Rake: (Caster Angle) 23.8 degrees

Trail: 97mm (3.8 inches)

This must mean the offset is different and therefore the upper triples must be different. Hence my 2.5-3mm difference.

Bren

Link to comment
Share on other sites

I think the answer is clear - use a matched triple clamp set. I've not seen anyone try to use an RC51 lower with a CBR upper as you are trying to do. What is the purpose for this?

To the contrary, using the drop-style CBR upper is common among people who have done the RC51 front end. The purpose is to gain length in the fork below the lower triple.

Veefer800Canuck, toktokkie, Toro1, and others have done this exact setup. I have used CBR1000RR lower/954 upper.

See attached spreadsheet.

Link to comment
Share on other sites

Well after further research the rake and trail of both bikes is different.

Honda RC51/SP1

Rake: (Caster Angle) 24.5 degrees

Trail: 100.5mm (3.96 inches)

Honda CBR954

Rake (Caster Angle): 23.45°

Trail: 97mm (3.8 inches)

Honda CBR 929

Rake: (Caster Angle) 23.8 degrees

Trail: 97mm (3.8 inches)

This must mean the offset is different and therefore the upper triples must be different. Hence my 2.5-3mm difference.

Bren

Rake and trail is a culmination of headstock angle, triple offset, and fork length, so your assumption is not necessarily correct.

Link to comment
Share on other sites

  • Member Contributer

I think the answer is clear - use a matched triple clamp set. I've not seen anyone try to use an RC51 lower with a CBR upper as you are trying to do. What is the purpose for this?

That is the de facto set-up. SP1 lower triple with the CBR929/954 upper.

Check all the SP1/2 swaps, they have gone this route.

I thought you´d know this, Jamie, as one of the suspension Pro´s around here?

One example

Link to comment
Share on other sites

  • Member Contributer

Well after further research the rake and trail of both bikes is different.

Honda RC51/SP1

Rake: (Caster Angle) 24.5 degrees

Trail: 100.5mm (3.96 inches)

Honda CBR954

Rake (Caster Angle): 23.45°

Trail: 97mm (3.8 inches)

Honda CBR 929

Rake: (Caster Angle) 23.8 degrees

Trail: 97mm (3.8 inches)

This must mean the offset is different and therefore the upper triples must be different. Hence my 2.5-3mm difference.

Bren

Rake and trail is a culmination of headstock angle, triple offset, and fork length, so your assumption is not necessarily correct.

True, I think, fork offset could actually be the same if rake and trail are different but that would also mean the relevant holes in the uppers would be at different angles to suit the rake and trail. Therefore the upper could quite easily slide onto the forks but because of the angle would not fit over the stem (?)

I´m no expert, just trying to figure this out.

Thanks all for the input :fing02:

Link to comment
Share on other sites

  • Member Contributer

Rake and trail is a culmination of headstock angle, triple offset, and fork length, so your assumption is not necessarily correct.

Nor necessarily incorrect.

I have a similar setup to Bren and mine was a very tight fit too (954 upper). Since everything was used but sold as "straight", I just assumed something wasn't. Also like Bren, I had another one (in my case a cbr1000rr upper) that slid on smoothly. I run a cbr1000rr lower.

Again since everything I have is used, I can't say with 100% certainty what is correct but I'm now leaning towards the 954 is a tad different.

Jamie, the early cbr1000rr uppers are gullwing and will work but they are "cosmetically challenged" because of the electronic steering damper mounting points.

Link to comment
Share on other sites

  • Member Contributer

Rake and trail is a culmination of headstock angle, triple offset, and fork length, so your assumption is not necessarily correct.

Nor necessarily incorrect.

I have a similar setup to Bren and mine was a very tight fit too (954 upper). Since everything was used but sold as "straight", I just assumed something wasn't. Also like Bren, I had another one (in my case a cbr1000rr upper) that slid on smoothly. I run a cbr1000rr lower.

Again since everything I have is used, I can't say with 100% certainty what is correct but I'm now leaning towards the 954 is a tad different.

Jamie, the early cbr1000rr uppers are gullwing and will work but they are "cosmetically challenged" because of the electronic steering damper mounting points.

Good to hear, I was starting to think I was the only one and/or something was seriously "unstraight".

So Foto what did you use in the end, the 954 or 1000rr? If the 954 Hammer or Grind?

Bren

Link to comment
Share on other sites

Rake and trail is a culmination of headstock angle, triple offset, and fork length, so your assumption is not necessarily correct.

True, I think, fork offset could actually be the same if rake and trail are different but that would also mean the relevant holes in the uppers would be at different angles to suit the rake and trail. Therefore the upper could quite easily slide onto the forks but because of the angle would not fit over the stem (?)

I´m no expert, just trying to figure this out.

Thanks all for the input :fing02:

I don't know of any honda triple clampo setups that don't have perpendicular holes; they all look like this from the side: |_ Not like this \_ Angle comes from the headstock/frame and fork length.

Rake and trail is a culmination of headstock angle, triple offset, and fork length, so your assumption is not necessarily correct.

Nor necessarily incorrect.

I have a similar setup to Bren and mine was a very tight fit too (954 upper). Since everything was used but sold as "straight", I just assumed something wasn't. Also like Bren, I had another one (in my case a cbr1000rr upper) that slid on smoothly. I run a cbr1000rr lower.

Again since everything I have is used, I can't say with 100% certainty what is correct but I'm now leaning towards the 954 is a tad different.

Jamie, the early cbr1000rr uppers are gullwing and will work but they are "cosmetically challenged" because of the electronic steering damper mounting points.

Agreed.

Link to comment
Share on other sites

  • Member Contributer

So Foto what did you use in the end, the 954 or 1000rr? If the 954 Hammer or Grind?

I'm running a cbr1000r lower (non-gullwing) and 954 upper with sp2 forks. I used a rubber mallet to make it work. :goofy:

Although mine looked like it was new out of the box, it could just be a coincidence that we both got tweaked 954 uppers. OR the 1000rr triple tree has a slightly different offset. :fing02:

Next time I have the front end apart, I'll try the 1000rr upper. It's not that ugly, really. :goofy:

Link to comment
Share on other sites

Something is definetly not straight. I can attest to both those triples being easily interchangeable without any force nor modifications as I've had both in hand and swapped them back and forth on the bike with forks in place and everything buttoned up.

I suspect the gullwing triple is at fault, as if it were anything else, stem, bearings, frame, then you'd have the exact same problem with BOTH triples.

Link to comment
Share on other sites

  • Member Contributer
The de facto set-up [is an] SP1 lower triple with the CBR929/954 upper.

Check all the SP1/2 swaps, they have gone this route.

The CBR929/954 lower works as well. I had an SP-1 lower whose top nut threads gave out - replaced with a CBR lower.

Link to comment
Share on other sites

  • Member Contributer

Something is definetly not straight. I can attest to both those triples being easily interchangeable without any force nor modifications as I've had both in hand and swapped them back and forth on the bike with forks in place and everything buttoned up.

I suspect the gullwing triple is at fault, as if it were anything else, stem, bearings, frame, then you'd have the exact same problem with BOTH triples.

I´m thinking you and Seb may be on to something.

Will have to check and report back.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...

Important Information

By using this site, you agree to our Privacy Policy.