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Info ZXR USD -> FZR fork conversion

Discussion in 'Tech Tips' started by ruckusman, Jul 16, 2016.

  1. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Interested to see what you did with the triple clamps or are you using the ZXR items? The blue spots use steel pistons and the gold spots use alloy pistons (lighter). The Fizzer calipers are 4 piston anyway, yes? I'm going to fit 4 piston onto my Honda. Those opposing pieces of junk belong on a scooter.
     
  2. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    I literally searched the net till I went crosseyed looking for 40mm offset triple clamps for USD forks, and that is before taking fork spacing - stem length or anything else into consideration...

    I was making a rod for my back - potentially Triumph Speed Triple 1050 triple clamps in more recent years have a 40mm offset, but they are not commonly found for cheap - l'll keep looking though

    The ZXR250 triples and their fork tube spacing (200mm) do work out well for the brake caliper adapter plates - another reason to stop obsessing over 40mm offset triples.

    Yes fizzer calipers are 4 piston - they had enough grip to dive the original forks right to the bottom no problems.

    Then I did some calculations, 40mm offset reduced to 35mm takes my trail numbers from 87mm -> ~92.5mm.
    To remedy this I would need to take the rake angle from 24.5 degrees to 23.5 degrees.

    Second set of calculations on what change to get the rake angle to 23.5 degrees is a ~27mm drop of the forks - this calculation was very rough as I was guesstimating some numbers based on the wheelbase.

    Recall that I've already raised the rear slightly when fitting the R6 rear shock and making shorter dogbones than required to regain stock ride height on the rear.

    So till I measure the actual head angle I can deal with any slight increase in trail.
     
    Last edited: May 16, 2018
  3. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    A 5mm increase in trail is going to make the bike feel more stable especially on fast sweeping corners. Any loss of turning ability will be minimal because 92 is still quite short.
     
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  4. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    Try searching for 48Y/25YM bearing's, or 25x48x13, or 25mm x 48mm x 13mm
    https://www.ebay.com.au/sch/i.html?...Loc=2&_osacat=0&_odkw=48Y-25yM#item362a6ab29e

    Cheapest one with freight is this,
    https://www.ebay.com.au/itm/Motorcy...869598?hash=item362a6ab29e:g:zxoAAOxyJX1TF73h

    But it look's like there aren't too many maker's of them
    Same bottom bearing is used in the following model's
    1983-1985 YTM200 TRI-MOTO
    1983-1985 YTM200E YAMAHAULER
    1983-1986 YTM225 TRI-MOTO
    1982-1983 XT550
    1984-1985 FJ600
    1974-1976 RD200
    1973-1975 RD250
    1973-1975 RD350
    1976-1979 RD400
    1984-1985 RZ350
    1987 SRX250
    1980-1982 SR250
    1981 SR250T
    1981-1983 XJ550 MAXIM
    1981-1983 XJ550R SECA
    1976-1977 XS360
    1977-1981 XS400
    1982-1983 XS400 MAXIM
    1988-1990 XV250 ROUTE 66
    2009-2013 XV250 V STAR 250
    1995-2007 XV250 VIRAGO
    1983 XV500 VIRAGO
    1987-1999 XV535 VIRAGO
    1986-1990 YX600 RADIAN
     
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  5. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    Mostly I'm pissed that I got charged 200% for a really low grade product via All Balls and I didn't save any time over getting them from the UK - live and learn.

    I will be avoiding All Balls in the future I think

    Going to get the one from ebay :thumb_ups:
     
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  6. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    Small update on this...

    Made a new bearing spacer for the wheel, used the original FZR one for length and bought some 25mm diameter 3mm wall aluminium tube - I reamed it out to get it over the 20mm axle. The ZXR250 spacer is too short by several millimetres.

    The tube down the centre of the of the wheel hub is tapered and the 25mm OD tube won't go all the way down, so I needed to remove a small amount of material with a dremel - 5 minute job.

    Spacing is different but not radically so - for test fitting I re-used both of the 20mm ID 42mm OD 12mm wide ZXR bearings, the RHS bearing will stay the same, on the LHS with the 12mm wide bearing I needed ~5.2mm of spacers to get the wheel centred, so I opted for a 20mm ID 42mm OD 16mm wide wheel bearing for the LHS (Speedo).
    This will mean I need a 1.2mm spacer/washer to get it all centred.

    Using the FZR speedo drive as the cable end of the drive is different between the FZR and ZXR, as well as the length differing (shorter) on ZXR. The speedo drive also needed to be reamed out to fit on the axle.

    I've drilled two small recesses into the speedo drive so that the ZXR fork protrusions are untouched and a little filing sees it fit into place in the same orientation as it is on the FZR forks normally.

    I've made a template for the brake caliper adapters which will be out of 5mm stainless. I chose stainless because the forks aren't threaded, so wanted 5mm for the thread for the bolts, same amount of material the ZXR calipers. Then the FZR calipers, which are threaded, will be bolted to the adapter plates from the inside with low profile wide head allen bolts.

    Once they're done it's just bolt it all up once the other steering bearing arrives in the post.

    I'll take some pics once I've got the caliper adapters fabricated.
     
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    Last edited: May 19, 2018
  7. Adam Mc

    Adam Mc Member

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    Hi @ruckusman I found this thread and am interested wondering if you made any progress?

    Sent from my SM-G975F using Tapatalk
     
  8. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    My Bike:
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    I kept going around in circles, what I did discover is that Hyosung GT250R and GT650R triple clamps are 210mm spacing and 40mm offset.

    There are other issues, the Hyosung lower triple clamp tube diameter being 54mm -v- 52mm for the ZXR250, easily solved with shims material to make up the difference.

    I have a set of Hyosung triples to be installed.

    I have swerved again as I got '05 ZX6R forks which take radial calipers, working through the rest as I've also got a TZR250 3" wide front, to be matched to a 4" wide rear

    So depending on what you want to achieve as to which direction to take.

    A simple change is entire ZXR250 front end, accept that the ZXR250 brakes are whet they are, or swap calipers/wheels etc

    Happy to discuss and share what I have learnt along the way if it can help you avoid mis-steps ;)
     
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  9. Andych

    Andych Moderator Staff Member Premium Member Contributing Member Dirty Wheel Club

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    I have also seen Later Aprillia front end grafted onto SRX250 which might be an option as well..
    The SRX and the FZR250 share the same bearing sizes and centre distance on the headstock.. No idea on what the Aprillia is though.
     
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  10. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Last edited: Mar 31, 2022
  11. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    There probably are some other USD triple clamps with a 40mm offset, I had quite a list of potential candidates, Triumphs, Ducatis and Aprillias among them, BUT getting a page which gives actual measurements is HELL

    If I'd bought every triple clamp that I put onto my evilbay watchlist as a potential candidate I'd have a garage full by now

    Someone would ask can I transplant this front end from this years bike and responses were weird and varied, almost no-one takes actual measurements

    Remember offset AND spacing come into play if you're swapping just forks and transplanting wheels to keep a consistent look, that's the downside to the ZXR250 transplant, the rear is 18" and I didn't manage to find a similar style wheel in 17"
     
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  12. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Which is why I label my entries at https://litetek.co/Guide_USD_ForkDatabase.html from unsubstantiated to proof supplied.

    Because they have no idea in hell what they are doing.
     
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  13. Adam Mc

    Adam Mc Member

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    So can you use zx250r usd forks and keep fzr front wheel and maybe put r6 or r1 calipers on?

    Sent from my SM-G975F using Tapatalk
     
  14. Adam Mc

    Adam Mc Member

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    Or use any use with oem wheel and r6/r1 calipers

    Sent from my SM-G975F using Tapatalk
     
  15. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    Yes, that's doable reasonably simply, you'll need to swap out wheel bearings for 20x42 bearings for the 20mm axle and make spacers, both between bearings and outside of wheel bearings to forks
    There are various 20x42 bearing in different widths

    Speedo drive can be drilled & reamed to fit 20mm axle, which is something that I have done

    Axial calipers will need adapter plates, I would recommend putting 20mm helicoils into the fork lug where the calipers bolt up then adapter plates can be bolted from the outside to the forks as are the calipers, which have threads

    This also means that the caliper adapter brackets are basically flat as opposed to ones that are Z shaped, simpler to make with much less work

    When it stops raining here I'll take some pics of calipers [I have MT07 axial calipers] placed where they should be so you can see what I mean

    When I remove the wheel I can give you measurements, may be a week at least with the current rainy weather
     
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  16. Adam Mc

    Adam Mc Member

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    That would be great thanks , look forward to seeing the photos

    Sent from my SM-G975F using Tapatalk
     
  17. Mike Green

    Mike Green Well-Known Member Premium Member

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    Nudge . . . . . . .
    I'm considering suspension improvements for one of my FZR chassis bikes and am interested in how this has ended up.
     
  18. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    I disassembled the forks - removing the mudguard was revealing - the chrome stanchions were scrubbed though the chrome on both sides to the size of a 50 cent piece and one tube was bent - not worth repairing or replacing IMO

    That then basically became a bust - very annoying - ZXR250 triples have 35mm offset, that triple does fit without too much fuss - just different bearings - as we've mentioned - forget the ZXR250 brakes - YUCK!

    If you want to keep the 40mm offset for steering geometry - hyosung GTR250 or GTR650 - I've put 2004 ZX6R forks into those triples with shims for the different tube diameters (smaller) - spring rate 0.85kg.mm which is very close for my enlarging and broadening backside.
    I got the whole enchilada forks, CBR1000 calipers and a radial master cylinder for a good price.

    It was down to what was available at the time I was looking that was close.

    Brake discs then need to be spaced out - due to no possibility of changing the spacing on radial calipers - that's achieved with hub spacers at the disc mount, BUT I've got to a TZR250 3" front with a 10mm wider hub - if you've got a lathe and can make disc rotor spacers that gets easier.

    Other option '99-'02 R6 front end - 40mm triple clamp spacing and forks have a very good reputation, I believe for period racing P6 they're a favourite with FZR400 pilots to keep within the rules

    I just never came across any locally for a decent price
     
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  19. Nathan Shore

    Nathan Shore Member

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    Hey guys got a question for the brains trust on some information i need/want.
    Ive got a 2012 ninja 250 that I engine swapped with a 2013 ninja 300 and running gear and for my next project want to replace the front work with a 1995 zxr250 tripple clamp and fork with the wheel. Im wanting to know if there are any 4Pot brake calipers on the market or even off of other model bikes that bolt directly into the fork without any modification or even with very little modification.
    thanks guys in advance.
     
  20. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    Some good info here
    https://www.litetek.co/Guide_USD_ForkDatabase.html

    Without considering anything else - the 45mm bolt spacing on the ZXR250 is problematic, however I saw someone had made some excellent adapter plates for different calipers with different bolt spacing on here recently.

    There are Brembo calipers with 40mm bolt spacing, but I would buy a set without knowing if they'd even go close to being able to fit.

    Hopefully they will chime in.
     

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