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  1. #1
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    F5 Custom parts

    Hi Guys! I'm pretty new here and this is my first forum thread of my own, here goes:

    I've got an F5 which I've always been pretty happy with, I live/ride in the UK with fairly tight, rocky or wooded and muddy courses in the main. I recently read about the new longer linkage piece being used to modify geometry and handling, but the exchange rate makes getting US made parts costly. So I thought I've have a go at making my own! The other problem with the linkage as it was is that the bushings seem to last me about half a dozen rides so I wondered about replacing the bushes with needle bearings of some kind.


    Started off with a nice piece of billet and a bearing or two.


    Bear in mind this wasn't CNC'd, it was cut and filed by hand! I'm very impatient so I rarely finish off any prototypes like this neatly.



    The finished item. Like I say, couldn't be bothered to take more pics in between, just wanted to get it on! It's pretty smooth, but obviously as it's hand made and a prototype I can't say how long it will last! (At this point I'll mention that the parts cost me about 20 or less ($30?), so as long as it lasts reasonably it should be a winner!)

    I also fancied trying a fixed brake mount for better rock clearance (and to save a little more weight):




    And last year I made this chain guide back plate to fit my preferences a little better (also cheap )


    Hope you like the parts, get tinkering! (don't forget to ride...)

    PS I just want to say that I didn't do all this to spite Chumba, they're great engineers. I'm just an impatient cheap skate!

  2. #2
    nerfherder
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    I think a lot of businesses get the starts from garage tinkering. Cool stuff. Keep it up.

  3. #3
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    you've got me thinking..... I might have to make my self a bearing link like that, my bushings are trashed and cash is tight.
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  4. #4
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    Quote Originally Posted by rollertoaster
    you've got me thinking..... I might have to make my self a bearing link like that, my bushings are trashed and cash is tight.
    Go for it, it's not that hard. Bearings are pretty cheap too! Ebay has loads of great places to get aluminium billet off cuts if you don't have ready access another way.

  5. #5
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    Well, some good news (I think!). Had my first ride with all the new parts on yesterday, been ridiculously busy with work of late so couldn't get out very far - took it to the local reclaimed quarry = nice and rocky The back end/linkage had a good work out and performed amazingly. The lower BB really helps in corners and makes the bike feel even more planted. Not missing the floater particularly either, though the tracks weren't very steep...

  6. #6
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    thanks for the inspiration. I started making a fixed brake mount tonight. I just happened to have a slab of 8mm thick aluminum laying around. The brake has been making such a racket lately I do my best to not use it. Might as well try a fixed mount and save some weight to boot. I'll post some pictures when I finish it.

    Any Idea if one of those needle bearings could be used to replace the bushing on the swing arm at the center of the link?
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  7. #7
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    I'm not a trained engineer, but I would hazard a guess that the size of needle bearing you could fit into the bushing spot on that link would die a violent death. As you may have seen the latest F5 linkage has bearing outboard of the swingarm mount hole and an axle which is press fitted through the whole lot, which is really the best way to do it. You *could* modify the exisiting bushing based linkage (by boring it out basically) to take needle rollers, which have huge load capacity. The problem with them is that they are very sensitive to dirt and sealing needs to be very good. I personally don't have the facility to do that kind of thing at home but if you have the tools, go for it!

    Looking forward to seeing your brake carrier, the difference is amazing. I'm sure yours will be neater than mine too!

  8. #8
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    I definitely wouldn't try to bore out the hole on the swing arm. I just didn't know if it was big enough to fit a sizable bearing into. Not that it matters but, I don't think dirt is much of an issue there. I just pulled mine apart last night for the first time in a year, and it was spotless. This is after several pressure washings, and very muddy races.

    I should have the brake carrier finished tonight or tommorrow, I can't wait to give it a try.
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  9. #9
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    It'll get the job done. Not the prettiest, but not bad for a grinder, jigsaw , drill press, and a sander. Saves about 200g. I still need to shorten the brake hose, but I want to ride it first before I commit



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  10. #10
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    Brake carrier

    Nice work! I'd be interested to know what you think of the performance now...my first test ride barely involved any braking as it's just not steep/quick enough. I mean, it works fine, but it's not really under the kind of conditions that a floating brake is supposed to help with. I have a feeling that I'm not going to miss the floater...

  11. #11
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    I got a chance to try it out this weekend. At first I felt like I was losing traction when breaking at the end of a long rocky dusty straight section turning into a steep section. But then I took a look at my rear tire, and the braking edge was pretty much gone. I through a new high roller on and I was unable to tell that I no longer had a floater. The suspension still remains active, and more importantly, it's quiet...

    I was having a pretty good race run yesterday and probably would have won my class if I didn't flat half way down. Oh well, that's racing, I rode it out to the finish because it was a double points race. Hopefully I didn't trash the rim, but it looks ok.
    Team _________

  12. #12
    BrassBalled DropbarNinja
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    some very inspiring things going on in this thread... XD

  13. #13
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    Just got back from Scotland, was riding the Fort William DH track today. It's one of the roughest full length world cup tracks around, the linkage piece I made seems to have stood up to it fine still smooth and no play. The only thing now is I want to get the BB down to about 13.5" with an even longer linkage (mine is not quite full 3.5, prob 3.45, might go to 3.575" or something), as the improvement to cornering has been amazing and the rocks have not given any problems yet...

  14. #14
    BrassBalled DropbarNinja
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    Quote Originally Posted by funkydrummer
    Just got back from Scotland, was riding the Fort William DH track today. It's one of the roughest full length world cup tracks around, the linkage piece I made seems to have stood up to it fine still smooth and no play. The only thing now is I want to get the BB down to about 13.5" with an even longer linkage (mine is not quite full 3.5, prob 3.45, might go to 3.575" or something), as the improvement to cornering has been amazing and the rocks have not given any problems yet...
    thats a really low bb... when full compressed... check to see how far the BB is from the ground... just saying... XD

  15. #15
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    Yeah, you're right. I always forget how much travel the bike has! I measured mine currently and it's at about 14.25", I'll probably just take it down to about 14" - I used to have an XC bike which I ran with 24" wheels for a short time. It was amazing for cornering and manoeuvrability but obviously not so hot for rougher high speed stuff, I just really like the low ground feel. As I say though, I rode Fort Bill yesterday which is essentially just a two mile rock garden and didn't have any grounding issues so far so I think low BB is the way forward! Again, thanks for picking up my technical issues!

  16. #16
    BrassBalled DropbarNinja
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    Quote Originally Posted by funkydrummer
    Yeah, you're right. I always forget how much travel the bike has! I measured mine currently and it's at about 14.25", I'll probably just take it down to about 14" - I used to have an XC bike which I ran with 24" wheels for a short time. It was amazing for cornering and manoeuvrability but obviously not so hot for rougher high speed stuff, I just really like the low ground feel. As I say though, I rode Fort Bill yesterday which is essentially just a two mile rock garden and didn't have any grounding issues so far so I think low BB is the way forward! Again, thanks for picking up my technical issues!
    the dogbone i got from chumba put my BB right at 14". Think thats the sweet spot cause when it's fully compressed front and back, you can pretty much see how close the bash guard is from the floor. It's like an inch or two or something... I'll see if i can find the pic...

  17. #17
    BrassBalled DropbarNinja
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    Couldnt find the one with the new link but here's a bottomed out pic with the original link...
    Attached Images Attached Images

  18. #18
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    My frame isn't the standard one (I have been helpfully informed by Alan at Chumba), it's a US hand-made one which used to belong to a racing team here in the UK. As I have found out during maintaining it, it's not quite the same as the standardised newer ones (or those made elsewhere, or an F4 etc). Maybe it's an earlier revision of the geometry?

    Part of wanting to make a slightly longer linkage is MKII of needle bearing seal system, However, until it dies I'm going to hammer MKI. When winter comes I'm going to resurrect my dad's lathe and make a proper version!

    PS nice photo - I take it you just landed a jump or something? It looks a bit like you're just bouncing on it!!

  19. #19
    BrassBalled DropbarNinja
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    Quote Originally Posted by funkydrummer
    My frame isn't the standard one (I have been helpfully informed by Alan at Chumba), it's a US hand-made one which used to belong to a racing team here in the UK. As I have found out during maintaining it, it's not quite the same as the standardised newer ones (or those made elsewhere, or an F4 etc). Maybe it's an earlier revision of the geometry?

    Part of wanting to make a slightly longer linkage is MKII of needle bearing seal system, However, until it dies I'm going to hammer MKI. When winter comes I'm going to resurrect my dad's lathe and make a proper version!

    PS nice photo - I take it you just landed a jump or something? It looks a bit like you're just bouncing on it!!
    aaaahhhh very cool. What were the differences in the frame if i may ask?

    Needle bearings... Talk about stiff eh? Haha

    yea, i kinda overshot the tranny on a step down... Bike looks funny fully squished... lols

  20. #20
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    Frame differences, as far as I know, it was basically shock and linkage hardware sizes, making it a bit awkward for replacements! Yeah, needle bearings in the linkage make it loads smoother...

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