R Nine T Front USD Front Fork in K100

[lumpus]

Hello Guys,

did anybody build up a K100 with a R Nine T USD Front Fork? Someone used a GSXR .... but R Nine T?

Thanks.

[racket]

I suppose this involves a scenario where you got front forks off a wrecked R nineT?

[MaraudeRS]

You mean these ones?
I thought about looking into these but not only do they look huge but I'm sure they'd cost more than the entire brick.


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[lumpus]

Yep! This one in black .... used from a wracked ... Could get it used for 700$

[MaraudeRS]

$700 isn't bad at all. I paid $620 for the gsxr set I bought.

Get the entire front end if you can. That whole setup would be sweet on a K100.

[racket]

You'd have to buy a custom triple tree set though to fit the K100 right?


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[lumpus]

Yes, I think so. Custom triple set is about 600$ in Germany ....

The main reason why I would like to use the R nine T fork is, that I can use BMW brake caliper..

What is the reason why many use the GSXR fork?

[racket]

So you're looking at like $1500 total? Better brakes are definitely nice, but you could get the BSK ECU kit for about that and get a serious increase in horsepower and performance. Or the 40mm throttle bodies. Just saying.

The main reason people go with GSXR forks is probably because there's a lot more of those than there are R nineT's.


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[Mike Flores]

I went with the GSXR 1000 setup for several reasons, primary reason being that I think the Showa forks with completely adjustable compression and rebound dampening are far more superior to the non adjusting R Nine T forks. Also, from the performance perspective, there are a lot more people tracking GSXR's than R Nine T's, so the performance parts aftermarket is also much larger.


Just my $0.02 USD


I would imagine that the R Nine T front end would be pretty plug and play though, as long as the steering stem is the same length as the K100's (which is the same as almost all of the airhead and oilhead R Bikes).

[rbm]

The GSXR 600 and 1000 forks have a triple tree where the length and diameter of the steering arbor are almost exactly right for the K100 headset, and the availability of headset bearings means it is easy to source over the counter races that fit, such that that little or no machining is necessary to adapt the parts.  Also the length of the GSXR forks is nearly the same as the K100's so that the steering geometry is not upset.  The RineT forks may not enjoy these advantages and you'd be in for a lot of fiddling to get things right.

[lumpus]

Thanks a lot for the detailed explanations ...  :2thumbup:

Yes.... the supply with R nine T forks is very thin ... and as I heard from some guys who drive a R nine T, the performance of the original setup is not the best ... all of them modified the forks ..

Is it possible to mount BREMBO caliper on the GSXR fork? How look the "original"?

[Mike Flores]

Is it possible to mount BREMBO caliper on the GSXR fork? How look the "original"?

2013 and newer GSXR front ends come with Brembo calipers stock.

[stomatomoto]

The GSXR 600 and 1000 forks have a triple tree where the length and diameter of the steering arbor are almost exactly right for the K100 headset, and the availability of headset bearings means it is easy to source over the counter races that fit, such that that little or no machining is necessary to adapt the parts.  Also the length of the GSXR forks is nearly the same as the K100's so that the steering geometry is not upset.  The RineT forks may not enjoy these advantages and you'd be in for a lot of fiddling to get things right.

Does this apply to K75's as well?

[rbm]

Yes, it applies to all classic-K's - k75/k100/k1100.

[lumpus]

Does it make a difference if I use a GSXR K7/8 or a K9/10?  ... little differences in dimensions ... anyway ... I need a custom triple  ...

K7/8 is Kayaba and K9/10 is Showa.

I can get a K7/8 in good condition for 230$.

[lumpus]

How long is your original K fork? Ich can't measure it because of the windshield..
The R nine T is 740mm... GsxR  is~730mm, right?!


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[lumpus]

The GSXR 600 and 1000 forks have a triple tree where the length and diameter of the steering arbor are almost exactly right for the K100 headset, and the availability of headset bearings means it is easy to source over the counter races that fit, such that that little or no machining is necessary to adapt the parts.  Also the length of the GSXR forks is nearly the same as the K100's so that the steering geometry is not upset.  The RineT forks may not enjoy these advantages and you'd be in for a lot of fiddling to get things right.

I'm not sure! Or I'm wrong? The K100 is 810mm. The R nine T is 740mm.

[Mike Flores]

I'm not sure! Or I'm wrong? The K100 is 810mm. The R nine T is 740mm.

It looks to me like you're measuring the fork tube diameter in that photo, not the length/diamter of the steering stem.


At the risk of sounding like a complete asshole, if you don't know the difference between those two things, a front end conversion might be over your head at this point in time.

[Laitch]

I'm not sure! Or I'm wrong? The K100 is 810mm. The R nine T is 740mm.

Show us a photo of what you are measuring taken at a distance that includes all of the object.

[bocutter Ed]

Looks to me like he's measuring forktube c/line to c/l

[lumpus]

Hi Guys,

I measured from the end of the inner tube (black cap) to the center of the axle hole. This is a metric meter rod. The length of the fork is 81cm....

If the GSXR, according to sam's chart is ~730mm, my K fork is 8cm longer.

[lumpus]

This is the measurement...


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[rbm]

Below, I'm posting all the information I've collected from various sources on the net about fork swaps for K-bikes.

K75 Headset Dimensions

Pivot Stem:
Length from top of lower triple clamp to top of threads:  176mm
Length from top of lower triple clamp to where tapering begins:  128mm
Diameter (to fit inside bearings):  28mm
Note that I ignored the portion of the steering stem that goes into the lower triple clamp
The K1200 axle is 20mm dia. and the k1100 axle is 25mm dia.

Frame:
Steering head length: 165mm
Steering bearing seat diameter:  52mm (BTW, this matches the outside diameter of the bearings I bought for the 1992)
Standard headset bearings (upper/lower) are 28 I.D. X 52 O.D. X 16 thick

Please also note that I used an analog calliper; it's possible that some rounding to the nearest mm occurred.



Friend's Experience with ’96-’06 Ninja ZX7R USD forks on K-bike
My friend uses a Ninja ZX7R front end on K75 stock headset.  Requires different 52mm bearings, but stem length is right on.  Uses Standard 20mm axle just like K100, only needs wheel spacers.  Uses 52/34mm roller bearings W24??? need to turn stem down only few 1/10 mm to size for bearing. Press out steering stem, turn on lathe, reinstall in lower triple.  Advised to pin stem for security.  Can also use aftermarket triple with adjustable offset.  Simpler to machine stem.  Standard Nisin brakes fit 320mm disks on K100 wheels.

Useful information from Triumph forum on Triumph Sprint conversion to USD fork
http://www.triumphrat.net/hinckley-classic-triples/164910-zx7r-96-03-usd-fork-conversion-legend.html

I've a set of forks & yokes on the way. They have a matching 25mm axle & take a variety of 4 pot or 6 pot (90mm, T3, Suzy TL/'Busa) mount axial calipers, aligned for a 320mm disc(s). So I plan to keep my Legend spoked front wheel.


*The ZX7R has some of the longest USD forks fitted to a sport bike at 30", much longer than Suzuki options. I expect a net lowering around 20mm. That will steepen rake, but less offset on the Kawa yokes will likely net out with a little more 'trail' - keeping things on the stable side.*


* edit: It turns out the ZX7R forks are 28.5" (73cm)
The ZX9R (early, B model) forks are ~ 30" (76cm)
However, the shorter length works fine when using the Kawa stem & top yoke.

http://www.triumphrat.net/t3-sport-touring-forum/164297-tokico-six-pot-measurement-needed-3.html

Fork length to axle c/l is 30". Offset is 30 to 35mm. Stem length 235mm. Axle is 25mm & the ZX7 used a mechanical speedo drive, so should have room for mine.
The tricky bit is the top which needs an OD of 52mm for the T3 frame. 30mm ID bearings are available, but not 35mm it seems. I've found just one supplier of a 34/52 taper roller - Pyramid, who seem to market fork seals & other stuff. There quality is a bit of an unknown? Presumably the 34/52 size fits some stock bikes & there would be an oem option, but I've no idea what machines.

The other option for the top is a double row angular contact ball race, 52mm OD, 40mm ID. It has the same load rating as the stock single row ball race on T3s. I figure a sleeve would be an easy fab - I have a mate with a lathe & he says no problem. Usefully this bearing is only 12mm deep, so might be handy if the stem length is tight - it's hard to be 100% about this not knowing exactly the respective depths of Kawa & Triumph top yokes, stem nuts etc. google_ad_section_end

Some ZX7R stem dimensions. The lower bearing mount diameter is 35.00mm, the upper 34.95mm. The top of the Legend headstock tube will be level with the top of the adjustment thread section, point 'A'. The lower seal will locate on the 6.4mm x 43mm diameter section.
The height of the headstock tube is 183mm, with bearing recesses top-18.8mm & bottom 17mm.

[lumpus]

Hi Guys!

I have now a like new R nine T USD with 900km in absolut perfect condition. Also a R1150 front wheel.
But now I regognized that the axle for the R nine T fits in a 6205 bearing with 50x25mm. The bearing for the 1150 is 47x20mm.  :mbird

Has anybody a solution for that???

Thanks

[bocutter Ed]

Your 6205 is 25x52x15 mm

I'll guess you need a 6304 which is 20x52x15 ...