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Forks and yokes and shocks

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    Forks and yokes and shocks

    I want to do a front end swap and new rear shock on my bros, what are my options in regards to fork/yoke (triple tree) combinations? Obviously if I go down the custom machined route I can have whatever I want, but

    Assuming I don't go the custom fabrication route, I would need something that could fit the bike even if it requires a bit of modification, but I don't want to loose the agility that it has - and I guess changing the rake, trail and going to wider tyres would do that xD

    What combinations have you used? Which ones do people like? What are your overall opinions so I can start forming a sense of direction on what to do with the chassis part of my build?
    Look out, a beer!

    #2
    A lot of Honda frontends are bolt on, many others can be fitted with a simple stem swap. So what do you want? Here are some random buzz-words:

    Fork/yoke offset, fork leg spacing, brakes, wheels, trail, rake, tyres, stering stops...

    To be more specific in answering your question I have been using CBR600F3, NSR250 SP ( MC28 ), upgraded Hawk and Bros frontends, a mix of CBR600F3/CBR400RR NC23/CBR1000RR/CBR600F2 parts together with some aftermarket parts to build a nice frontend, another setup was using CBR600RR PC35 with PFM brakes and Dymag wheels and Ohlins 25mm cartridges. Now I am looking at fitting some Ohlins FKS cartridges to see what they are like...

    Others have fitted CBR1000RR frontends (various years), CBR600RR PC40, VFR750, VFR800 etc. Lots and lots...

    One important thing to consider is that most other modern frontends have shorter offsets than the RC31, so without compensation there will be even more trail.

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      #3
      For shocks I have been using stock, modified CBR900RR SC28, various Ohlins, Penske, Nitron - all modified. I think the one I like best is the Penske I built based on a 8987 originally for a R1, then probably my modified Ohlins - but today it is easiest to just buy a new Nitron (outside US) or a Penske (in the US). Very fine products ready to bolt on...

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        #4
        Ohhh wow thank you so much for the detailed reply! lots of googling and ebay-ing for me to do tonight! I don't have access to a garage for too long so I need to really plan my rebuild to maximise my use of time.. Probably going to be asking lots of silly questions here though xD
        Look out, a beer!

        Comment


          #5
          Jan covered it pretty well. Ducati triples have threaded in or pressed in stems....easy to swap in a Honda stem if you're handy..I used a 749 frontend....kinda equates to...cbr954 in spec.

          Comment


            #6
            right, I guess as a follow up on this and for posterity (since I've been reading so so many forum threads after JanM's replies, keywords really helped btw!):

            I decided to go with an aftermarket shock. I spent a good while looking at modifying a CBR900RR shock because you can get one used for cheap, but after getting quotes on how much it would cost to get it re-sprung and re-valved, aftermarket was not too dissimilar (and well, new). Im going with either Wilbers or Nitron.

            As for forks, BTT's comment opened a new path for me that I haven't considered. Unfortunately I'm not completely decided yet because my BROS already has emulators in it (thank you PO). I like USD for looks and dual disks, but its going to be an expensive swap. I'm happy to go with aftermarket clocks, it will take time to get the funds but I always planned to swap them. Right now im thinking either 05 or 09 CBR600RR front end, as I can get either for fairly cheap, but a pair of ducati 749 and 999 forks both have become avail for the same price (each with both yokes). I'm considering ducati because it looks like they have larger offsets..

            Any further input will be much welcomed
            Look out, a beer!

            Comment


              #7
              If you go with the Duc 749, including wheels, there are a couple members that have modified spindles to fit the Duc rear wheel.
              '89 Hawk a.k.a. The RallyHawk (my son's now!) | '89 Hawk a.k.a. The Deuce | Spare Parts/Dented Learner Bike | '13 Tacoma | '69 Falcon (currently getting reassembled! )

              I've spent most of my money on women, beer, cars and motorcycles. The rest of it I just wasted.

              Comment


                #8
                I always wanted to try the VFR800 yokes with CBR600F4 forks... or VFR750 yokes with CBR600F3 forks...

                The 749 frontend is very nice with a slightly softer setup, massive brakes.

                Comment


                  #9
                  Originally Posted by JanM View Post
                  I always wanted to try the VFR800 yokes with CBR600F4 forks... or VFR750 yokes with CBR600F3 forks...
                  Explain. Is this because they have a different offset than the forks they are meant for (i.e. VFR800 different from CBR600F4 offset)?

                  Comment


                    #10
                    riot, I think a lot of VFR's have 40mm offsets (trying to confirm which years atm), so i guess this way you could do the fork swap without adding trail?
                    Look out, a beer!

                    Comment


                      #11
                      Yes, more offset for less trail by using the VFR yokes. Fork spacing is the same for VFR/CBR 41mm tubes and VFR/CBR 43 mm tubes, so the complete CBR front fits in the VFR yokes for same diameters.

                      Comment


                        #12
                        Originally Posted by JanM View Post
                        Yes, more offset for less trail by using the VFR yokes. Fork spacing is the same for VFR/CBR 41mm tubes and VFR/CBR 43 mm tubes, so the complete CBR front fits in the VFR yokes for same diameters.
                        Very interesting.I admire your meticulous approach. I figured ONE of the 749 discs was enough.....especially with the big 6pot.
                        Let's clear something up.....More trail =slower steering(like a Flat-track bike) Less trail =quicker.......Have I got that right?
                        Last edited by behindthetimes; 03-12-2018, 09:26 AM.

                        Comment


                          #13
                          Originally Posted by JanM View Post
                          I always wanted to try the VFR800 yokes with CBR600F4 forks... or VFR750 yokes with CBR600F3 forks...

                          The 749 frontend is very nice with a slightly softer setup, massive brakes.
                          JD built these for me and you're exactly correct.We left the stock springs in there and installed Penske GoldValves.They are stiff/plush on my 315lb Hawk with me at 165 full suit. They compliment my Ohlins with 1300lb spring perfectly.

                          Comment


                            #14
                            Originally Posted by JanM View Post
                            Yes, more offset for less trail by using the VFR yokes. Fork spacing is the same for VFR/CBR 41mm tubes and VFR/CBR 43 mm tubes, so the complete CBR front fits in the VFR yokes for same diameters.
                            Oh neat. Can anyone confirm what the exact offsets are for the 43mm forks? I have an F4 front end, perhaps the VFR triples can help me avoid pestering WW about adjustable triples again. Any other options?

                            Comment


                              #15
                              Originally Posted by behindthetimes View Post
                              ...Let's clear something up.....More trail =slower steering(like a Flat-track bike) Less trail =quicker.......Have I got that right?
                              Yes. But working with geometry you can't change one thing without changing something else at the same time - in the case of adding offset to get less trail for a quicker steering, you also get a longer wheelbase, which requires more lean angle for the same turn and speed. For the RC31 there is already a lot of trail, and by fitting a lower front and a taller rear everything quickens up. If using a more modern front with less offset the change also gives more trail. Having the option of using more offset is just another parameter.

                              The focus on trail is usually related to setting up modern racebikes, when you add a longer shock and taller rear tire trail goes down, and this is bad on a racebike as it takes away the front end feeling midturn and usually leads to the front washing out and a crash. Too little trail is bad, too much is sluggish...

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