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My Moto Guzzi V7 III TT/NTX/Dual-Sport/Scrambler
Dirk_S:
Wishing to modify my V7 further to tackle questionable paths AND desiring shorter trail measurement for the sake of my arms when steering the sidecar, I decided to jump for some dual-sport forks with leading axle. The V7 models have used 40mm forks for many years now. I stuck with that size for my search, as I have no want in going to length and changing my triple tree like some Airhead owners do with their dual-sport conversions.
I initially looked at two options—the short-lived, rare (in the Western Hemisphere) V35/65 TT, and the early BMW GS bikes. The TT used smaller forks, so they got the boot. When the BMW R80 G/S evolved into the R80/R100 GS, they jumped up to 40mm forks. I searched and posted, but the few GS forks floating around were out of my price range. I saw one or two other dual sports that were 40mm, but they appeared to be even more obscure. Backtracking to the Guzzi, it turns out the TT’s replacement, the NTX 350/650, got the 40mm fork treatment. A few queries and posts of interest on ADVRider and Facebook over the course of a week led me to a few Italian sellers offering forks for sale. I purchased a set for $275 shipped a month ago, and they arrived one week later.
The forks look pretty straight, but I haven’t taken them apart to see what the internals are like yet--hoping to get to that in the next week. They carry an extra 4” or so in length.
Now Dirk, you might ask, won’t the extra 4” of travel take away the advantage of the reduced trail created by the leading axle and thus negate steering improvement for sidecar use? To that my response is “how did you even know that if you don’t ride sidecars?” But also, I BELIEVE I can raise the forks up in the triples to bring the bike back down and gain that benefit back. Yes…a whole 4” raised up in the triples. I think they clear the handlebars. Tell me why it’s a bad idea.
Anyway.
One advantage of the R80/R100 GS forks is the fork brace: the GS has four mounting points—2 front, 2 rear—for a more substantial hold, whereas the NTX forks utilize a little hoop in the rear that’s thin as spaghetti (crickets). I found that the NTX’s fork leg diameter measures at 57.5mm. The V7 triple sets the forks at 195mm apart, center-to-center, so off I went searching for an aftermarket brace. I discovered Tarzocchi fork braces, and see they make one for an older Yamaha with 58mm fork legs. A bit nervous about the 0.5mm diameter difference, when the brace arrived I tried it out, and it appears to clamp down well enough… hopefully.
The next step was to procure an axle. The NTX front utilizes a 17mm axle, the V7 uses a 20mm axle, so I had a decision to make. Wishing to not deviate too far from stock measurements, I chose to favor the V7 wheels, especially considering my sidecar uses a duplicate front V7 wheel, and that axle is also 20mm. I contemplated purchasing a used V7 axle and drilling out the axle holes in the NTX forks to fit the V7 spindle, but I decided to get an old NTX axle and just see how it fits. In addition to the diameter difference, the NTX forks are 15mm closer (180mm) than the V7 forks (195mm), so axle length could very well be an issue. Luckily on the NTX, the axle’s big end pops out 1-2 cm, so maybe there was a chance it could work.
Received the spare spindle from TLMN and tested it out:
Big end had to be driven all the way near flush with the fork, but it just fits! I lose the hole for easy removal, but I suppose I can just make due with some light taps on the small end to drive it out.
To bring the 17mm diameter of the spindle up to 20mm, I purchased a 20mm OD stainless tube that needed to be turned slightly for the bearings to fit onto. Had a shipyard engineer friend help me out with that one:
Onto figuring out centering and spacers for the wheel. Pretty fortunate that I have a spare front hub sitting around (soon to be used for a 21” wheel build). I looked at the spacers on my V7 and found the right side to be 4mm longer than the left side. Measuring everything on the front hub, I realized it’s not quite as centered as I assumed. There are a couple extra mm on the end of the brake side, which led me to realize I should be focusing more on bearing-to-bearing length. But then I was surprised to discover that the bearing-to-bearing placement isn’t quite centered either, compared to the spoke placement on both sides. Regardless of the centering find, I figured focusing on the stock spacers’ 4mm difference is all that needs to carry over to the NTX forks and axle.
Another tidbit that shows the gods slightly favor me—or at least like to build a story for an even better fail at the end—the big end of the spindle ends precisely at the hub bearing—when everything is centered. With one thread remaining outside the the small side’s nut, and the big side driven in nearly as far as it should go, that big end terminates perfectly as a spacer. All I did was make that side’s spacer (22mm KTM spacer) match the distance (28mm):
Spacers cut and cleaned up, it was time to mock it up.
Everything looks good so far, and the hub’s centered.
Next up—disassemble/inspect the forks, and begin mocking up the caliper adapter. Looking to keep the V7’s Brembos on for convenience—why bother changing them up?
Anyway.
bigbikerrick:
Wow, Dirk, Im impressed! That was alot of work, getting things to fit and work properly. I really like how your bike is coming together.
Rick
Pescatore:
Whaaaat? Off-road sidecar? Reminds me of the Vespa trail races.
Interested to see the forks sticking up from the triple. Hopefully still below the top of the handlebars.
Are the clamps strong enough? Usually the forks have a stop at the top triple.
Dirk_S:
A year and a half later of distractions and procrastination, and I have enough of an update to share! Note that I changed the title of this thread; the previous title was solely focused on the forks.
Last weekend was yet another rainy one up in Maine. I had recently finished a poster and t-shirt design for Phoenix Cycle Shop’s Blood, Sweat and Gears moto show:
Looking forward to doing a linoleum cut and maybe a full color illustration in time to sell at the show and elsewhere.
With some time to kill in the apartment, I decided to jump back on this V7 ADV build I’ve been slowly working on. Plus, I’m riding out to OH for my former Amish sister’s wedding, and I’d very much like to take the V7 in its finished chubby enduro guise.
I already had the axle figured out back in 2023, having realized the original NTX axle will JUST fit through the forks distanced out to the V7’s specs; the nut/threaded end leaves one extra thread exposed when torqued up, and the other end sits perfectly flush with the axle clamp.
A couple modified end spacers—one off a V7, the other for a KTM—and a long one to make up for the differences in wheel bearing sizes (keeping in mind I chose to stick with the V7 hub for the 21” wheel).
I built the front and rear wheels last year in my new apartment in Maine. Thankful my roommate can handle me occasionally building wheels in the dining room:
For the fork brace, I first tried out a Tarozzi brace. It came too close to the tire, so I added spacers. It still didn’t quite work out, so I searched elsewhere, scanning the webs for bikes that matched the V7 fork distance and NTX leg diameter. Discovered the old T120 and T140 Bonnevilles were right about the same, and found a couple aftermarket options. Went for the Russell James / British Fork Co. fork brace made for those bikes, though I had to get the clamp diameter milled out by a millimeter or so. The fork brace is hefty, adjustable in the right way, looks classic, and has the perfect arch rise for the 21” tire:
For the brake caliper, I’m keeping the V7’s stock 4 pot Brembo on. When comparing the caliper positioning over the brake rotor, I found the NTX caliper tabs sit 3-4mm farther back from the hub than the tabs on the V7 forks, and the NTX tabs are spaced apart differently from the V7’s. Originally I planned to make a single adaptor machined out of aluminum stock that would recess in 3mm while providing mounting holes for the new caliper position, but once I hit the Bridgeport with a friend, I realized that using two plates cut to shape, the right thickness to recess the caliper, and sandwiching the NTX mounting tabs would be WAY simpler. However—though simpler, it still required some trial and error, multiple mockups. Cardboard and plastic sheets to the rescue. This was the step I JUST finished last weekend:
I know I should’ve taken the forks apart, but I was too anxious and simply trusted the seller that they’re in good condition. When I drained the old oil, added the new 20w Motul fork oil, and began compressing, I get a noise on both forks—not sure if this sound is normal or not. Video link below:
https://youtu.be/Z5EUgzzUMxU?si=WUTeAFdOUnAO_QVB
And so, everything is built and ready to install:
Today I gave myself a 3-hour lunch break to do just that in between rainy sessions. Only got to the front section:
Rocking a bit of a chopper vibe with only the front done. I completely forgot about the speed sensor, so until I make a mount for it, it’ll just be tied up to keep from dangling. I discovered a few years ago that removing / disabling the front wheel speed sensor will disable ABS / traction control as expected, but retains the speedometer function, unlike removing the ABS fuse, which cuts off the entire dash.
Hoping to have time before the weekend to throw on the 180mm Hagon shocks and the 18” rear wheel.
Parashootist:
Nice work. I just picked up a 2015 v7 special and would like to build it into a scrambler. The 18/21 wheels and longer suspension are definitely things I'd love to do. I wonder how long you can go in the rear before experiencing issues with the joint for the shaft drive?
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