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Reducing trail
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Bob Herman
Posted 3/22/2016 8:51 AM (#88365)
Subject: Reducing trail


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Hi Folks -
I've just joined this forum. I'm new to sidecars but have about 50 years of solo motorcycling under my belt.
I recently bolted a Velorex 562 to a 1975 Moto Guzzi T-3 for the sole purpose of bringing my dog along on camping trips.
Yes, I know the Velorex is intended for use with smaller/lighter bikes, and perhaps I'll upgrade the axle at some point. But for now this is the rig I have.
With just a few hundred miles on the rig, two issues have arisen that I think I'll want to address:
-A bit more power would be a good thing;
-A bit less steering effort would be a very good thing.

I live in the Colorado Rockies at 8000' where all engines make considerable less HP than at sea level, and I can add displacement with a 1000cc top end, but the steering effort issue is what I'm seeking advice for here. I've done enough research to learn that reducing trail is the route to lighter steering effort. I'd love to go with a leading link front end, but the cost for admission is breathtaking and not realistic for this rig. I've seen photos of a modification someone made to standard telescopic forks by bolting on plates to the fork stanchions which relocate the axle forward to reduce trail. This option might be doable for me, but I'd like some knowledgeable opinions about this.

Anyone have experience with such a modification - good news, bad news? Is there an optimum trail specification that I should strive for?
Thanks in advance for any perspectives on this or other means to reduce steering effort. I plan to put a lot of miles on this rig and want to enjoy it.
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VLAD
Posted 3/22/2016 1:05 PM (#88370 - in reply to #88365)
Subject: RE: Reducing trail



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Location: DENVER, COLORADO
I think it called Side Effects by www.sidecars.ca
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Rob D
Posted 3/22/2016 1:32 PM (#88371 - in reply to #88365)
Subject: RE: Reducing trail


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Posts: 37
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Location: Midcoast Maine

 

Hey Bob,

The Steerite / Side Effects is a nice unit as VLAD mentioned,  there is also the EZ Steer although I do not see a set for the Tonti Framed Guzzi listed ... http://www.championsidecars.com/ez-steer.html

They look to be a pricey little item also...  possibly look around for a used Unit Forks Leading Link assembly.  I was very fortunate to find one a few years ago for the EV Hack.

Might be worth a call though...

Best,

Rob ~ aka radguzzi elsewhere...  

 

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Bob Herman
Posted 3/22/2016 3:00 PM (#88377 - in reply to #88365)
Subject: Re: Reducing trail


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Posts: 42
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Thanks, guys. I'd love to find a used LL front end, but thus far have had no luck.
The modified triple clamps would be a viable solution, with the advantage that no mods. to the forks/brakes/etc. would be required. And I do have some extra Guzzi triple clamps. Do I understand that the Steerite process is to modify existing triples?

I was hoping to fix the steering issue for less than a thousand dollars. Not because it isn't worth that much but because if I need to spend that much, and also invest in some horsepower, I'll start wondering if I shouldn't sell the bike I have and get something already set up as a hack tow like a Ural.
The plates I was trying to describe are not triple clamps, but rather they bolt on to the fork stanchions, attach at caliper brackets and existing axle holes and move everything forward.
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Rob D
Posted 3/22/2016 3:41 PM (#88378 - in reply to #88377)
Subject: Re: Reducing trail


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Posts: 37
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Location: Midcoast Maine

Bob Herman - 3/22/2016 3:00 PM The plates I was trying to describe are not triple clamps, but rather they bolt on to the fork stanchions, attach at caliper brackets and existing axle holes and move everything forward.

 

I believe you intend to say that these plates would bolt onto the lower legs, not the stanchions.  I am not at all familiar with that set up but I guess it would work.   If you do that, is there bolting for the calipers still...?  Sounds good in theory but I would have to see the plates to discern just how rugged they are.  I understand you to say that they Essentially would move the axle forward accomplishing the correct or better geometry.

I cannot tell you how the Steerrite process works...  or whether that includes modification of the existing triples.   

 

Best,

Rob

 

 

 

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Hack'n
Posted 3/22/2016 4:35 PM (#88381 - in reply to #88365)
Subject: Re: Reducing trail



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What you are describing is what DMC used to call (and maybe still does) leading legs.

I would suggest sending your spare trees to Side Effects for modification.

Lonnie
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Al Olme
Posted 3/22/2016 5:46 PM (#88382 - in reply to #88377)
Subject: Re: Reducing trail


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Location: Minneapolis, Minnesota
Bob Herman - 3/22/2016 2:00 PM

<>Not because it isn't worth that much but because if I need to spend that much, and also invest in some horsepower, I'll start wondering if I shouldn't sell the bike I have and get something already set up as a hack tow like a Ural. <>


Bob, you just said Ural and horsepower in the same sentence. hehe! Changing the gearing on your Goose isn't easy since it's a shafty but lacing on a smaller diameter rim might be a cheaper way to get better performance with your sidecar.

The "leading legs" are a viable option but remember that they put extra stress on your fork tubes. A big part of the reason to go to a leading link is the extra stiffness and strength your get to accomodate the side loads that you experience driving a sidecar rig that you don't see on a solo bike.

Doesn't it just suck that everything is a compromise?
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Bob Herman
Posted 3/22/2016 6:16 PM (#88383 - in reply to #88365)
Subject: Re: Reducing trail


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Posts: 42
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Rob, you are right of course about lower legs vs. stanchions. And yeah, Ural and horsepower may sound oxymoronic. Truth be told I want to make this Guzzi rig work optimally, not replace it.
Al, very good point about the added stress to my fork tubes. And given that these old tubes are only 34 or 35mm, I wouldn't want to stress them more than I can help. I've been thinking a fork brace is called for if I retain the original forks. But I happen to have the forks (and all front end parts) from a Yamaha FJ1200. Much stouter, and with better brakes to boot. I guess I could go that way and get the FJ triple clamps modified by Side Effects.
Lonnie, I'm new here but I suspect by your signature you are an expert on these things. Thanks for your advice.
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Lloyd
Posted 3/22/2016 9:14 PM (#88387 - in reply to #88365)
Subject: Re: Reducing trail


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Location: Columbiaville, MI.
I had a set of modified triple trees made by Side Effects, one difference between theirs and others on the market is that they add one degree of camber plus the normal 4-5 degrees of rake. They make them for sidecar rigs, others make them mostly for trikes. Give Brock Smith a call at Side Effects and see if he has them available for your ride. He even loaned me the correct socket to fit my steering head nut, and I sent it back to him with my stock trees, and recommended the correct fork oil for my set up, as he couldn't ship it with the trees from Canada. They are great people to work with.
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Bob Herman
Posted 3/22/2016 10:50 PM (#88390 - in reply to #88365)
Subject: Re: Reducing trail


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Lloyd, thanks for that.
Bob
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Bob Herman
Posted 3/23/2016 9:05 AM (#88394 - in reply to #88365)
Subject: Re: Reducing trail


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Posts: 42
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So here's another idea: why not find a pair of forks with axle ahead of the stanchions' axis - such as BMW airhead - and slide them into stock Guzzi triple clamps? That will reduce trail, though without taking measurements and doing arithmetic I don't know offhand if that would be enough change in trail to make real difference in steering effort. Anyone have an answer on this idea?
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jaydmc
Posted 3/23/2016 10:28 AM (#88396 - in reply to #88365)
Subject: Re: Reducing trail


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We use to make clamps that go on the top end of the fork to move the entire fork forward. We no longer offer these however they would be fairly easy for some one to have made. We were thinking about an inexpensive way to make them again, just got to busy with other things. We were going to work with a company that claims that they can water jet cut them out of one inch think plate aluminium. All we would have for your bike are proper not "universal" mounts as well as we do offer aleading link front end as the one we make for the G5 / Convert should be the same.
Jay G
DMC sidecars
www.dmcsidecars.com
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Bob Herman
Posted 3/23/2016 11:27 AM (#88400 - in reply to #88365)
Subject: Re: Reducing trail


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Jay, I'm trying to envision clamps that "go on the top end of the fork..." I gather you're not talking about modified triple clamps, or you would have described them as such. So can you briefly explain what you mean?
I would love to have a leading link front end. That would be optimal, certainly. But what I'm working with is a 40-year old Guzzi worth not much more than the cost of that conversion - and with a shed full of other vintage bikes and a humble retirement income, it's hard to justify that kind of investment. Hence my earlier comment about weighing the cost of any trail-reducing mods etc. against selling the T-3 and biting the bullet for a dedicated hack rig.

And while I'm at it: I notice at the DMC website you offer triple clamps for the Guzzi EV bikes. Anything for an old tonti bike kicking around?

Edited by Bob Herman 3/23/2016 11:42 AM
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DirtyDR
Posted 3/23/2016 2:15 PM (#88407 - in reply to #88365)
Subject: Re: Reducing trail



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Where are you at in Colorado Bob? I am up in Edwards.
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jaydmc
Posted 3/23/2016 2:29 PM (#88408 - in reply to #88365)
Subject: Re: Reducing trail


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You keep the original tree's in place. You then slide in some old fork tubes cut down such that they are a bit longer then the distance between the tree's. Then the clamps clamp onto the salvage fork tubes and your original forks clamp to the other side of the clamps moving the entire forks forward by about 2 inches with out changing their angle.
Nothing for the Toni frames, we are set up to rework the tree's on Eldorado's which is what my wife runs. I have attached a photo of clamps we use to make for the G-5 / Convert.
I could not find photo's on the bike.
Jay G
DMC sidecars
www.dmcsidecars.com
866-638-1793



(motoguzzitripletree.JPG)



Attachments
----------------
Attachments motoguzzitripletree.JPG (257KB - 3 downloads)
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Bob Herman
Posted 3/23/2016 3:40 PM (#88413 - in reply to #88365)
Subject: Re: Reducing trail


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Posts: 42
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Jay, thanks for the clarification and photos. I wonder if I could get a competent and bored machinist to make me up a set like that?

Dana: I'm in Crestone, down in the Sangre de Cristo Mountains just north of the sand dunes.
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Rob D
Posted 3/24/2016 7:13 AM (#88419 - in reply to #88413)
Subject: Re: Reducing trail


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Posts: 37
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Location: Midcoast Maine

Bob Herman - 3/23/2016 3:40 PM Jay, thanks for the clarification and photos. I wonder if I could get a competent and bored machinist to make me up a set like that? Dana: I'm in Crestone, down in the Sangre de Cristo Mountains just north of the sand dunes.

 

Bob,

IF Jay would release the drawing on the triple tree extension, I can turn you to a great machinist and Guzzi Guy in South Dakota.

 =========================

 

Jay,

That is a great idea...

 

Best,

Rob

 

 

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Bob Herman
Posted 3/24/2016 7:47 AM (#88420 - in reply to #88365)
Subject: Re: Reducing trail


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Posts: 42
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Thanks, Rob. It so happens I know a machinist here in Colorado who recently lightened a Guzzi flywheel for me, and I would be happy to bring him a project like this.
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Bob Herman
Posted 3/24/2016 8:15 AM (#88421 - in reply to #88408)
Subject: Re: Reducing trail


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Posts: 42
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Jay: I like the simplicity of this idea. Two questions:

-Structurally, has this modification proven up to the stresses of long term use?

-Is there an inherent advantage or disadvantage to moving the fork legs forward without increasing rake?

Thanks for sharing your knowledge, I really appreciate it.
Bob
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jaydmc
Posted 3/24/2016 10:37 AM (#88422 - in reply to #88365)
Subject: Re: Reducing trail


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This set up works fine and has held up long term. As a clarification. Even with triple tree's we are not changing the "rake" it may look like we are but we are not. To change rake the angle of the head stock on the bike would need to be changed. All we are doing is reducing trail. To reduce trail very much over simplified all you need do is move the front wheel forward. In the case of the clamps we do this by moving the entire fork assembly. I do not have drawings on this. It has been a very long time since we built these and we had a flood a dozen years ago that wiped out our hard drive and the drive that was backing it up. No idea why we still have this photo which was taken sitting on the hot tub of my old house which we worked out of back in 1998-1999 time frame. Figuring it out is not all that hard, you need to measure fork tube diameter, fork tube spacing and figure out how much you want to reduce trail by. In general most people like to have trail end up at about 2 inches although unless you live in the flat lands I like to go a bit more. If you bike now has 4 inches of trail and you want two inches then move the forks forward by 2 inches. A less expensive way to possibly make these rather then machining them from billet is to have them water jet cut at which point making one or making 100 there is not much difference in the machining cost just more material cost.
The reason we developed these is simply because they are cheaper then most other methods. We also did them for air head BMW's (my wife's R100S we dropped down to 1.2 inches of trail) and the GL1000
Jay G
DMC sidecars
www.dmcsidecars.com
866-638-1793
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Bob Herman
Posted 3/24/2016 10:48 AM (#88423 - in reply to #88365)
Subject: Re: Reducing trail


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Posts: 42
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Thanks, Jay, for taking the time to explain all this. And sure: coming up with the dimensions is no problem. And a hot tub is a great place to mull over such things!
So, to clarify: when you modify triple clamps, you're moving the fork legs out but they are still at right angles to the the triples? So yeah, no change in rake.
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jaydmc
Posted 3/24/2016 10:55 AM (#88424 - in reply to #88365)
Subject: Re: Reducing trail


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Yes, no change to the angle at all which is why these should be able to be made by a really good water jet company. But again, even if we changed the angle of the forks in the clamps we would not be changing the rake! Rake is the angle of the head set not the angle of the forks.
Jay G
DMC sidecars
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Bob Herman
Posted 3/24/2016 10:56 AM (#88425 - in reply to #88365)
Subject: Re: Reducing trail


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Gotcha.
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