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Club Cafe' Cafe Racers; the Thruxton and other custom cafe styled bikes.

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Old 02-12-2011, 12:50 AM   #1 (permalink)
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GSX-R 1000 front end on a Thruxton. Surprisingly easy to do.

Hi all,

I've finally finished my latest modification, and I thought I'd share and post a couple of pics. This time round, I finished putting the front end from a 2007 GSX-R 1000 on my Thruxton. Apperance-wise, she's exactly what I was hoping for - a more aggressive, meaner looking Thruxton with USD forks and twin brake discs. And after surviving my first shakedown ride around the block, I'm also really happy with the handling. Here are some pics:






(that digital gauge is temporary, and it's all cracked and stuff because I spilled petrol on it. I'll be swapping it out for an analog gauge sometime soon).

This mod replaces the SV650 front end that I had on prior to this, and I have to say that the GSX-R front end was actually easier to do than the SV650. Surprisingly easy in fact, and I'll write a bit about how it was done for anyone who might be interested in doing the same.

Overall, I wouldn't mind if the GSX-R forks were a bit longer as the front is a little bit low, but this is something I'll compensate a little bit for with some shorter-than-stock rear shocks later in the year (I'm aiming for a slightly slammed look so I don't mind giving up a bit of steering geometry), and I've traded upright ergonomics for a more hunched over, racer's crouch. But the upside of that is I had an absolute blast on my shakedown ride, and I was still taking it very easy. When I'm confident the front isn't going to fall apart and I've scrubbed-in the new front tyre, I think my bike is going to be a ton of fun to ride.

I'll describe what was required to make this work, for those who are interested. The lower steering bearing is identical between the Thruxton and the GSX-R, so all that is required is a custom upper steering bearing, which you can get from here (The SV650 guys who upgrade to GSX-R front ends also need the same size bearing).

The GSX-R steering stem is just the right size, so no need to press it out and swap it with the Thruxton's. The GSX-R's steering stops are too wide, so you'll need to drill and tap a couple of holes to put in some bolts to act as new steering stops. And here's where the GSX-R front end swap is easier than the SV650 - you don't need to grind off the old steering stops on the GSX-R lower yoke whereas you do if you go for a SV650 front end swap. So, with just a custom steering bearing and two bolts, the whole GSX-R steering assembly will slide right into the Thruxton's steering tube.

Because I had a 2009 model Thruxton, all my switchgear was for a 1" bar, which meant a lot of rewiring to get the 7/8" switchgear connected. I think the earlier, clip on Thruxtons all used 7/8" clip ons, so if you have one of those you can use your existing switchgear to make life much easier.

I couldn't really come up with a good idea for mounting the headlights, so I reused the stock Thruxton's and made some ghetto brackets out of hose clamps:

Not the greatest, but for 4 x $1.50, they're not too bad.

The indicators (not stock, but some aftermarket ones I had spare) I mounted on a bracket screwed into the GSX-R's lower steering yoke, where the steering damper usually goes. Again, not the greatest, but they work fine.

The bar end mirrors are held in place by a tightening/expanding screw thing inside the 'bars. I used a stock SV650 clutch perch and lever and Brembo radial master cylinder (one of the best upgrades I've done). I also had to get new brake hoses.

My throttle cables are a bit too long, so I've had to rotate them in such a way to take up the slack. Really, the thing to do would be to snip the nipples off, shorten and resolder them. But you can make the stock throttle cables work if you're creative with the routing.

I think that's about it. Hopefully some of that will be useful to anyone else contemplating something like this.
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2009 EFI Thruxton (Red): GSX-R 1000 front end, SV650 rear wheel, other usual mods
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Old 02-12-2011, 01:28 AM   #2 (permalink)
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Wow, you've done a lot of work.
You obviously have the skills to do it.
Looks great to me, a unique Thruxton.
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Old 02-12-2011, 03:52 AM   #3 (permalink)
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First, nice job!

- but you gotta do something with those headlight brackets!
Aztec do some brackets for various size fork tubes - http://www.aztec8.com/catalog/c4_p1.html

Quote:
Originally Posted by grumple View Post
... Overall, I wouldn't mind if the GSX-R forks were a bit longer as the front is a little bit low....
06+ 600/750 are 18mm longer than the 1000's; also the offset on those triples is 30mm vs the 28mm of the 07/08 1000.
Those features would make for less difference from stock geometry and also more ground clearance.
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Old 02-13-2011, 02:28 AM   #4 (permalink)
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Quote:
Originally Posted by DEcosse View Post
06+ 600/750 are 18mm longer than the 1000's; also the offset on those triples is 30mm vs the 28mm of the 07/08 1000.
Yup. I think I read your very informative GSX-R fork matrix on the SV forums after I got the GSX-R 1000 forks, and didn't realise the 1000 forks were shorter. That's very good info though, and might be useful for anyone contemplating this mod.

I did specifically want the 1000 forks; my reasoning being that they'd be sprung for a heavier bike than the 600/750, and so the stock forks would be a better match for the heavier Thruxton, but I also didn't realise that the 600/750 had better internals (Kayaba vs. Showa).

Still, having said all that, with these forks just set to neutral at the moment (i.e. not dialed in yet), the front of the bike already feels really solid and confidence inspiring, and definitely a huge improvement over the SV650 front end (I'd upgraded the internals with cartridge emulators and .85kg/mm springs, but I think they were still undersprung for the Thruxton's weight). I'm happy with these stiffer forks, and don't know if I really would even notice the difference between the kayaba and showa internals.
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Old 02-13-2011, 02:56 AM   #5 (permalink)
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Quote:
Originally Posted by grumple View Post
...I did specifically want the 1000 forks; my reasoning being that they'd be sprung for a heavier bike than the 600/750...
Actually you might be surprised that the Black 750 Showa forks have the stiffest springs of all - 1kg/mm
Even the 06+600 have .900 springs.
The 07/08 1000 Springs are just a tad under the 750s at .976
05/06 1000 were .950.

I haven't tried the 07/08 1000 to be honest so not sure (or fair!) to compare; I do prefer the 750 Showas damping over the 05/06 1000 I had on the S3 previously.
(Had the Kayabas on originally and put the 750 Showas on my TL - when I was about to sell the TL I swapped them over when I realized my preference between them)

One thing, the 07/08 1000's are going to have a lot less flex (not that flex is noticeable anyway with USD) - the 1000's tubes are 56mm vs 53mm on the 600/750.

But honestly, they are ALL improvement over the OEM, so regardless of what you choose, sure to be better.
And LOOKS fanatastic also!
The choice could easily come down to purely aesthetics of the different colour combos - and there's nothing wrong with that either!

Sorry to detract from you super accomplishment - it really looks fantastic and I'm sure will ride really well also!
Again, congrats on a great job.
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Old 02-13-2011, 06:23 AM   #6 (permalink)
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Grumple;

Nice job, very cool and aggressive look. Now, I am all about looks so here we go

1. Could you strip the gold anodizing and go natural or anodize the fork tubes black (or balance it out with some gold Ohlins!)?
2. What about a smaller, alloy rather than chrome, headlamp?
3. Move the pee cup or replace with a smaller black alloy reservoir.
4. Add a small, round spedo or tach centered off the upper tripple clamp.

OK, I thought I was satisfied with my bike but as Spring approaches in Ohio, I now have a list of mods!D This is the worst addicition I have ever faced.

Love the look of your front end (and entire bike), well done!
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Old 02-13-2011, 10:07 AM   #7 (permalink)
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Super neat mod!

I would love to see someone do this though using the stock wheels - more machining and not a direct bolt on I know but interesting.
Thanks for doing this, brilliant!
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Old 02-13-2011, 04:54 PM   #8 (permalink)
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Quote:
Originally Posted by BuckeyeBike View Post
... Now, I am all about looks so here we go

1. Could you strip the gold anodizing and go natural or anodize the fork tubes black ...
The 07+ Showas are black and combined with the length and offset, may be a simple choice for your own project BuckeyeBike

Quote:
Originally Posted by Whitehurst View Post
... I would love to see someone do this though using the stock wheels - more machining and not a direct bolt on I know but interesting.
Probably easiest way would be to retain the 17mm axle and use spacer sleeves in the forks. That would be the simplest machining exercise and also preserve the OEM speedo drive.
The challenge would be whether the spacing of the rotor would be correct axially.
Center-line of rotor to center-line of wheel is 66mm on GSXR USD forks
- if narrower than this on the OEM wheel, add a spacer between rotor and wheel - if wider, gets a bit more complicated
(although there are alternative Suzuki triples that could be used to possibly alleviate that e.g using SRAD GSXR triple clamps - these are 7mm wider - that would put the caliper at 69.5mm on center from wheel center)
Additionally, regardless, would require a 10mm caliper spacer and longer bolts to accommodate the 330mm rotor.

But the twin rotors as per Grumple's great looking conversion are nice feature - both aesthetically and also functionally, give you a LOT more stopping power!

Here is a reference thread I created on our sister site SVRider which may be of benefit to anyone contemplating this - a lot of dimensional info available as well as what components mix/match between the myriad of GSXR models.

http://forum.svrider.com/showthread.php?t=135430

The special top-bearing that Grumple referred in first post is available from Zoran at TWFRacing

NONE of this is any criticism of Grumples choices - just to answer questions regarding different permutations. That's the nice thing about customizing - everyone has different perspective on what they want their end result to be. And there are many different combinations with Suzuki parts so they lend themselves nicely to USD conversion for this bike.
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Old 02-13-2011, 07:21 PM   #9 (permalink)
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Well said DEcosse . . . I applaud anyone who is willing to take a chance, try something new and then share it like grumple.

Thanks for the details.
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Old 02-13-2011, 09:11 PM   #10 (permalink)
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Yup, I certainly don't take anything other than possible suggestions and constructive criticism from the comments. I'm glad there's some discussion, and hopefully some inspiration too

Like DEcosse said, there's lots of options with these Suzuki parts, so it really is quite easy to mix and match based on aesthetics and/or functionality, depending on your preference. I'm really enjoying trying different things to get my bike where I want it - a modern, agressive, bratty, cafe racer. I like the mix of modern, high-tech parts (e.g. USD forks, upgraded braking) with a ratty and stripped down, 'just go' look (e.g. header wrap, 'MacGuyvered' headlight brackets). And then it all comes together into something that you can actually ride! Lots of fun.

Plus I'm planning on the 994, or if I don't talk myself out of it, the TPUSA 1087 kit later in the year, so I think upgrading at least the brakes before then is probably a good idea
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