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Discussion Starter · #1 ·
Help! I just purchased a crashed 2005 Thruxton and must replace the forks (plus more, tank, instrument, headlight wheel, disc...oh, what did I do???). Anyways, I love thiis bike and figure it was worth saving.
Can I swap forks and triples from other Triumph models with 41mm tubes? Say a Bonnie America?...or other models? Any insight is greatly appreciated. Thanks.

ps any links or help locating pieces and parts is appreciated too!
[email protected]
Thanks again,
Mike
 

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Help! I just purchased a crashed 2005 Thruxton and must replace the forks (plus more, tank, instrument, headlight wheel, disc...oh, what did I do???). Anyways, I love this bike and figure it was worth saving. Can I swap forks and triples from other Triumph models with 41mm tubes? Say a Bonnie America?...or other models? Any insight is greatly appreciated. Thanks. ps any links or help locating pieces and parts is appreciated too!
[email protected]
Thanks again,
Mike
Good man, saving a Thruxton! I own a 2007 Thrux, and I have been reading up a bit on the published specs, in particular the differences in wheelbase, front end rake and trail, etc., between the twins models.

It seems the Thruxton does indeed have a different set of triple clamps from the standard Bonneville with a different rake and trail. Also, the wheel sizes of 17" rear and 18" front, along with longer (14.25") rear shocks make a difference in overall handling characteristics. The Thrux rims are satin finish aluminum alloy vs. chromed steel on the other models.

The Thruxton also has pre-load adjuster caps on the forks, but you should be able to salvage them from your crashed bike and put them on your new forks.

So, in a nutshell, if you want to keep the same handling of the Thruxton you will need the OEM upper and lower triple clamps. That will necessitate the use of standard clip-ons unless you go with one of the new 2009 upper triple clamps which will accept a tubular handlebar. (I'm thinking about one of those for my bike but they are pricey...about $150 USD!)

I believe the 41mm fork tubes and sliders are universal across the model range. If anybody else has different info, please speak up!

Cheers, and thanks for saving a Thrux! I did the same thing for a poor old 1973 Honda CB750 four. It was in such pitiful condition I just had to buy it and bring it back to life...I'm very glad I did.

BLIGHT
 

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Discussion Starter · #3 ·
Thruxton Fork help

Hi Blight,
Thanks for your response and info on he rest of ther Thruxton's specs. The top of my triple tree yoke set up is OK, bottom part with the stem is tweaked. I guess I am wondering if all current (1999+) Triumph triple trees will fit?..lenght? ..diameter? ...bearing sets??
I have the opportunity to purchase a fork set up with trips from a 2004 Bonnie America...would this work? Also have seen a front fork set up from a 2003 Sprint ST for sale...wondering if this is an option too?..HELP!!
Trying to fix this on an extremely tight-low, what the hell do I think I'm doing in this current American economy state budget, so,... new parts are out of the question as you can imagine...thus my search for front end parts and set ups that are interchangeable.
..as for saving ths ol' Gal. I've always dreamed of owning a British twin, just damn sexy bikes. I even enjoy sitting in my garage with a cold beer just looking at it! Actually just getting back into bikes after a 22 year break raising a family. Looking forward to getting this one back together. Again, I appreciate all shared information.
Thanks again!
Mike
 

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Hi Blight,
Thanks for your response and info on he rest of ther Thruxton's specs. The top of my triple tree yoke set up is OK, bottom part with the stem is tweaked. I guess I am wondering if all current (1999+) Triumph triple trees will fit?..lenght? ..diameter? ...bearing sets??
I have the opportunity to purchase a fork set up with trips from a 2004 Bonnie America...would this work?
Mike
Hi Mike, here's an idea if you have the time... go to BikeBandit.com and look in the OEM part 'fiche' section for the Triumph Thruxton. Find their in-house part number for that piece and write it down.

Then, go back to the Bonneville and America and Scrambler sections to see if it is the same part number(s). My guess is that it is the same! The differences in rake and trail between models is slight, and might just be due to the wheel diameter differences and different rear shock length. Although the Twins range looks a lot different, it's basically the same bike underneath.

Let us know what you find out... I've been toying with the idea of putting a used (cheap) Bonnie or Scrambler upper triple on my Thrux so I could use a low, flat tubular handlebar (like my CB400F) instead of clip-ons.

Cheers,
BLIGHT
 

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Personally, I wouldn't mess with replacing the tubes with stock triumph parts. Get some CBR600F3 tubes & install them into your stock sliders...cartridge forks for less jack than you would pay for (used) stock triumph parts. FWIW, I bought mine for $50 off ebay.

The triple trees need to be purchased in sets, as previously noted, since the rake is different from bonnie to thruxton. The difference in rake isn't much, however, so get whatever trees come available on the used market. Don't go with speedmaster/america trees unless you plan on running the cast wheels...the spacing is wider on those & your spoked hub won't work.

Good luck.

Cheers,

--Rich
 

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The triple trees need to be purchased in sets, as previously noted, since the rake is different from bonnie to thruxton.
--Rich
The rake is not set by the yokes. It's set by the angle of the steering head in the frame. The Trail is determined by the offset in the yokes amongst other things like wheel diameter etc.
The difference in rake between the Thruxton and the Bonnie is because they have different length rear shocks with longer ones on the Thruxton standing the rear up higher which in turn steepens the steering head angle (rake).
 

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The rake is not set by the yokes. It's set by the angle of the steering head in the frame. The Trail is determined by the offset in the yokes amongst other things like wheel diameter etc. The difference in rake between the Thruxton and the Bonnie is because they have different length rear shocks with longer ones on the Thruxton standing the rear up higher which in turn steepens the steering head angle (rake).
I did some digging through the published specs and here is how the various 'new twins' compare rake & trail wise:

2001-2004 Bonneville & T100: 29 deg rake, 117mm trail
2005 on Bonneville & T100: 28 deg rake, 110mm trail
America & Speedmaster: 33.3 deg rake, 153mm trail
Thruxton: 27 deg rake, 97mm trail

Sooo... it appears with the trail varying so much that the triple clamps are different, on the America anyway. And, with the rake varying 6.3 degrees from America to Thruxton, the America must have a different steering head angle too.

Like blacktiger said, the other models are close enough in rake that the rear-shock lengths and wheel diameters would account for the rake variations of only a degree or two.

I would like to someday put a 17" front wheel on the Thruxton (wire spokes though) I know a couple of folks here have put cast 17" wheels front & rear on their bikes and said the handling was more responsive. I just like the look of the old-school wire-spoked wheels on these retro bikes.

However..the new SE sure looks sharp though with those 17 inchers front & rear! Hmmmm....

Cheers!
BLIGHT
 

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Discussion Starter · #8 ·
Thanks Guys, Blight, BeemerRich and Black Tiger.
Alot of usefull info. It looks like I have my work cut out for me, Looking at my forks tonight, I my need to get new tubes and springs...only, I hope. I plan on staying with the Thruxton triples, guess I'm affraid of altering the handleing characteristics of the bike. so off to ebay I go..any one know of another good Triumph salvage link?
Thanks again, you've all been real helpful.
Mike
 

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The rake is not set by the yokes. It's set by the angle of the steering head in the frame. The Trail is determined by the offset in the yokes amongst other things like wheel diameter etc.
The difference in rake between the Thruxton and the Bonnie is because they have different length rear shocks with longer ones on the Thruxton standing the rear up higher which in turn steepens the steering head angle (rake).
My point was that you cannot use a bonneville top tree with a thruxton lower yoke and visa-versa. If this is what you are implying, you are giving bad counsel on a public forum on this matter.

I know for an absolute fact that the triple tree sets cannot be mixed & matched...I've physically tried it and it does not work.

Regards,

--Rich
 
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