Tonti Frame Changes - Question

[lazlokovacs]

Hi everyone,

during the life of the tonti bikes there were two major changes... swingarm length and headstock length...

Anyone know why they lengthened the steering stem?

what benefit does it bring?

[pete mcgee]

They did that for the look they wanted for the mk4 and 5 lemans.
Benefit?
IMO the bike looked taller, did it improve anything else? Questionable.
This was also a time when someone thought 16 inch front wheels were a good idea. So we're back to questionable benefits again.
Simply looks and marketing.

[Cdn850T5NT]

Hi everyone,

during the life of the tonti bikes there were two major changes... swingarm length and headstock length...

Anyone know why they lengthened the steering stem?

what benefit does it bring?

First brought in in late 1983 with the 850 T5... with a 16" frt and rear wheel. Used on the later T5, SP II, LeMans IV in 1985.  It is gusseted back to the top tube. A bit stiffer I suppose...

[Antietam Classic Cycle]

The California II preceded the T5 with the tall neck. It was for more strength in the steering head area.

[wirespokes]

I can see how a longer steering head could be more leverage against the forks tweaking. The brace, though, is on the back side so would make it stronger front to back . I wouldn't have thought braking forces would be a problem, and if it was cornering issues, bracing on the side would have been needed.

I'm curious how much of a difference in strength there really is. Do the bikes with taller steering heads handle better?

Besides the taller steering head and various brackets for different models, there's also the rear frame rails that kick up. Some kick up higher than others. And then there's the breather-in-the-frame system that came out sometime in the 80s.

Are there any other changes?

[guzzista]

Coil brackets that place coils in the middle of the engine V in V7 Sport through 850T,  removed in T3  to mount coils behind left side cover, as well as master cylinder mounts  added inside right side frame triangle. Also, no steering neck lock  and welded tab on steering neck sticking out forward in early models. And these are changes I am aware  of on short necks, alone, possibly missing others...

[Mr Revhead]

What about changes for the Californias? EV etc, I thought there were some tweaks there?

[Cdn850T5NT]

The California II preceded the T5 with the tall neck. It was for more strength in the steering head area.

Right you are re the Cal II (it came out before the first T5)...but then the early T5...the first series that came out (16" wheels, frt and back) did NOT have the long (and gusseted) steering tube...of that I'm sure. The late '84 (call it an '85 model year) T5 did have the long steering tube.

[rocker59]

What about changes for the Californias? EV etc, I thought there were some tweaks there?

2002 bikes received the wide swingarm.

[Groover]

The real reason for the tall head tube change is to fit the newer 17 number VIN 

[Testarossa]

My long-stem Mille does not handle better than my short-stem T.

[lazlokovacs]

My long-stem Mille does not handle better than my short-stem T.

Interesting data point, thanks...

Is one more comfortable than the other?

[LowRyter]

I am curious after reading this.

Are the Tonti frames built to the same dimensions and geometry with the distinction between models being different swingarms lengths?  Or are the frames themselves dimensionally different?

It would seem odd that my '98 EV would be the same as a 1000s or LeMans iV.  It might explain why the EV handles so well despite floor boards.

[Testarossa]

Is one more comfortable than the other?

Solo, the T feels smaller and lighter -- at 5'8" with a 29-inch inseam I prefer it. Two-up, my wife prefers the Mille. While I can flat-foot the Mille it looks and feels taller. I dropped the triple clamps half an inch so the handling feels as quick as the T.

[Groover]

Some have 1/2" wider back rails where the rear shocks mount. For example, the Le Mans 1000 is 1/2" wider on the rails than the V1000 G5. This is to line up better with the wider swingarms offered for that generation. The 2002+ EV I believe have an even wider swingarm, but I'm not sure if they also widened the rear rail on the frame as well or not. 

[Two Checks]

IIRC the early  "16 front wheel models with tall necks handled too quickly and they put on longer forks which slows the steering.
I have the SP II w 16" wheel and a Cal III with the w i d e bars so I can't tell if one turns quicker. Its easier on the Cal III due to more leverage.

[mtiberio]

at some point in the California evolution, probably when they went with the high offset "long" u-joint, they moved the entire engine/trans assembly to the right to get the output shaft of the trans slightly right so the wider tires could still be on the bike centerline. the actual changes might be limited to the removable lower frame rails and/or spacers.

[Cdn850T5NT]

IIRC the early  "16 front wheel models with tall necks handled too quickly and they put on longer forks which slows the steering.
I have the SP II w 16" wheel and a Cal III with the w i d e bars so I can't tell if one turns quicker. Its easier on the Cal III due to more leverage.

Two Checks - what make/model/size of frt tire do you have on your SP II? What about rear? Do you find windy day stability a challenge? What about lousy pavement (re stability)?  Seems that with fork mounted fairing + 16" frt wheel you could have a fairly sensitive steering stability at speed...?

[Two Checks]

Quote from: Cdn850T5NT on Today at 04:33:04 PM

Two Checks - what make/model/size of frt tire do you have on your SP II? What about rear? Do you find windy day stability a challenge? What about lousy pavement (re stability)?  Seems that with fork mounted fairing + 16" frt wheel you could have a fairly sensitive steering stability at speed...?

IIRC its a 110-90 but in honesty I haven't ridden it in some years but it's going out to be made roadworthy soon.

That is one damn stable mount at 80 in a moderate rain. Some mods could be made but it's a good foul weather fairing.

[80CX100]

I am curious after reading this.

Are the Tonti frames built to the same dimensions and geometry with the distinction between models being different swingarms lengths?  Or are the frames themselves dimensionally different?

I'm very curious on this as well.

My CX100 Lemans (ll), just doesn't appear to be as big and roomy to me as my G5. I'm not sure if it's just as a result of different body styles, fitment and construction, but working on the bikes I felt like there was a lot more room and space on the G5.

I had a biatch of a time fitting a pair of big blue Bosch coils on the 1980 CX100, but when I look at the 1979 G5, I think I could probably easily install a couple of pair of them, no problem, optical illusion or not?, IDK.

I'm particularly interested in the similarity of the lower frame rails. I picked up a mint set of lower frame rails,floor boards, stands, linkages etc from Ed Milich and when I install them on the G5 (no I won't sell the pegs, lol), I'd love to somehow use the now spare, extra big police style side stand on my CX100. I removed the oem SS a long time ago, it was a hazard more than anything else, fwiw.

Is the lower frame rail with SS from a G5 a simple swap over to a CX100 (Lemans ll). The huge(ugly) welded bracket for the SS looks like it might interfere with the tighter lines of the header pipe.

Has anyone done or seen that swap, if so any issues or cautions?

Interesting comment from Groover about the wider California Tonti frame tails, IDKT.

If I'm stiff&cold or it's early in the season, breaking in the old muscles etc, it doesn't matter if it's my Cal Vin or the CX100, as soon as I sit and get going on a Tonti frame bike, it's a good possibility that I'll get a cramp in my hip from the crowded short foot to hip space; yet the bikes are a completely different feeling; the CX100 I'm sitting on it like a bike, but the Cal Vin feels like I'm sitting on a couch, fwiw.

Tia

Kelly

[rocker59]

Are the Tonti frames built to the same dimensions and geometry with the distinction between models being different swingarms lengths?  Or are the frames themselves dimensionally different?

It would seem odd that my '98 EV would be the same as a 1000s or LeMans iV.  It might explain why the EV handles so well despite floor boards.

John,

Basically, yes.  They're "the same". 

There are running changes and detail variations model to model, but your '98 EV has a frame that is very much like the original, 25 years earlier.

That's why the 1990s and 2000s Californias handle so nice.  They're direct descendents of the V7 Sport and 850 LeMans.

Tonti's frame was a good design that endured from 1971 to 2011.   40-years!

 

[Cdn850T5NT]

Quote from: Cdn850T5NT on Today at 04:33:04 PM

Two Checks - what make/model/size of frt tire do you have on your SP II? What about rear? Do you find windy day stability a challenge? What about lousy pavement (re stability)?  Seems that with fork mounted fairing + 16" frt wheel you could have a fairly sensitive steering stability at speed...?

IIRC its a 110-90 but in honesty I haven't ridden it in some years but it's going out to be made roadworthy soon.

That is one damn stable mount at 80 in a moderate rain. Some mods could be made but it's a good foul weather fairing.

Yes, I've heard that the SPII fairing, provided that you are not too tall, really has great coverage against the weather.

This Youtube video:  https://www.youtube.com/watch?v=_hGRHazmi3w is a rather longish 20 minutes or so.  It compares the SP to the SP II.  The fellow from Australia seems to poo-poo the 16" front wheel on the Guzzi.  I do note that he does NOT have the original style of front tire tread, comprising a straight groove down the middle of the tire.  I also note that the OEM tire fitment had this same central groove for both front and rear tire.  I think they were Michelin A48, M48, front / rear.

Some have said that tire tread pattern does not seem to matter.  Others have said that it DOES matter.  Mostly front tire tread pattern... but also rear.

YMMV.

Cheers and Thanks!

[LowRyter]

John,

Basically, yes.  They're "the same". 

There are running changes and detail variations model to model, but your '98 EV has a frame that is very much like the original, 25 years earlier.

That's why the 1990s and 2000s Californias handle so nice.  They're direct descendents of the V7 Sport and 850 LeMans.

Tonti's frame was a good design that endured from 1971 to 2011.   40-years!

Thanks Mike.  They say there's something about a Harley that you can't know until you ride one.  I have and didn't get it. 

But OTOH, there is something about Italian bikes.  Guzzi and Ducs just handle and have the right feel to them.   Even the bikes that don't have huge power numbers, seem to have a great power curve to match the gearing.   I guess it's hard to quantify.  Ride Japanese, Brit and German bikes and they just don't give the pleasure or confidence that Italian bikes give.

Frankly, I don't think a Tonti bike would be out of step for any bike designed in 2020 for the same range of power and handling.  It works.  And works well.

[rocker59]

Frankly, I don't think a Tonti bike would be out of step for any bike designed in 2020 for the same range of power and handling.  It works.  And works well.

I agree.  It's really too bad that Guzzi didn't expand on the Bellagio idea.  Tonti frame with CARC swingarm.  It had all sorts of possibilities!

[LowRyter]

I agree.  It's really too bad that Guzzi didn't expand on the Bellagio idea.  Tonti frame with CARC swingarm.  It had all sorts of possibilities!

Really, I find no need for a CARC on my EV.  I guess they got the tires and length and stiffness of the drive shaft to match the torque curve, because the rear end of the bike is totally benign and stable.   

[rocker59]

Really, I find no need for a CARC on my EV.  I guess they got the tires and length and stiffness of the drive shaft to match the torque curve, because the rear end of the bike is totally benign and stable.

The EVs are good, but mainly the longer travel with the mono-shock CARC on the Bellagio would be better on rough roads than the twin-shock Californias.  Add USD forks to a Bellagio and WOW!  Great fun! 

Well, a guy can dream, can't he?

[LowRyter]

The EVs are good, but mainly the longer travel with the mono-shock CARC on the Bellagio would be better on rough roads than the twin-shock Californias.  Add USD forks to a Bellagio and WOW!  Great fun! 

Well, a guy can dream, can't he?

Hard to believe there have been so many Guzzi defeats that have been snatched from the jaws of victory.    I don't know how much feet you have left when keep shooting them.  Enough metaphors, I am thinking of two Flying Fortresses in the shop since the summer awaiting some nickel and dime parts preventing them from being repaired and back on the road again.