Dreaded Tonti Weave

[Shrek]

After experiencing ill Handleing on many bikes over the years and in particular on my Lemans 1000 and California Stone.I thought i would share my experience as others i talk to and read about suffer the same dreaded Tonti weave while cornering.
My Lemans would gradually loose its renound stability from time to time.I would check the usual culprits,worn tyres,head stem bearings,fork action,swing arm bearings and tightness of all frame bolts etc

1 i have found that steering dampers,in particular the std black friction type fitted to many Tonti,s can cause bad handleing.They become worn and grabby,inconsistant friction,with age and dont allow a smooth steering action.Transferring unwanted forces back into the chassis.
In my opinion no Tonti(except maybe those with 16" front wheels) needs a steering damper.I have thrown all my dampers in the trash and have never experienced a tank slapper.Daytona included.
They dont improve handleing,they hinder it.If you insist on using one it would be wise to use a good quality oil damped type.

2 Badly worn,squared off rear tyres gradually decrease stability.

3 The most common cause of the dreaded Tonti Weave for me has been worn head stem bearings.
Too tight,can also be a problem.A little loose is not a problem.
This is not always obvious.Jacking the front wheel off the ground and rotating the steering stem,either by grasping the fork legs or handlebars doesnt always show a problem.
I have learnt to become very sensitive to feel for this check.
I hold the handlebar ends lightly with two fingers,close my eyes(it seems to help me for some reason) and very slowly rotate the steering from left to right, close to centered.
I am feeling for the slightest notch which will be felt with the wheel pointing straight ahead or a slight looseness as it centres followed by slight tightening just off centre in both directions.
Any abnormality felt,however small will indicate wear on the steering head bearings races.
Improved handling will be gained by replacing both bearings.
Dont be tempted to cheat by replacing the outer races only.They can be tapped out of the head stock easily,while the bottom inner race with rollers is a little more difficult and must be pressed,cut or pulled off.
Failing to replace all components wont resolve the problem as indentations will also be present on the inner races under the rollers.I tried being lazy,only having to do it all again.
The outer races will probably show dark vertical lines (as pictured above)where the rollers impact while the steering is centered.These can often be felt with your fingernail.
Replacing worn bearings will always improve handleing.
When cornering we turn the bars slightly until the required lean angle is achieved.The steering is offset slightly to retain this arc.If we have slight grooves in the bearings the steering wants to return to this looser worn spot,the steering straightens,but we want the bike to keep cornering so we make slight adjustments to the steering and it wants to slip back into its worn groove again........
This is my theory atleast.
If you are experiencing cornering flex or wobbles and havnt replaced your head stem bearings in say,the last five years or dont remember ever replacing them.
This is often the No 1 overlooked cause.

I replace my head stem bearings between 3-5 years and always notice an improvement.

My ill handleing 2001 California?
I rebuilt the forks with cartridge emulators,rebound mod and the correct weight oil.
Fitted new tyres.
Replaced Ikon shocks with Hagon Nitro,s.
These all improved the wobble but...
The biggest improvement i got in handleing was replacing the head stem bearings.
Yes,i have a short memory....

Fresh steering head bearings are the key for stable handleing Tonti,s

 

[Tony F]

Hi

I've got a 1979 SP1000 and my findings over many years are close to yours.

Steering dampers make a nice noise when they hit the bottom of the rubbish bin!

I found the SP to be particularly sensitive to rear tyre profile, a flattened tyre profile would induce a slow weave as the speed got up. Possibly the fairing contributed to this. This could happen at very low mileage depending on the tyre profile and tread pattern. Best results I've found is with tyres that don't have a straight central tread groove. Dunlop GT501 is one I've had good results and long mileage from.

Early tontis (79-82 approx.) with the wide fork spacing and plastic mudguards also benefit from a fork brace.

The factory tyre pressures of 29/34 don't seem enough on more modern tyres, I use 33/38.

I've had good life from steering bearings and haven't seen much wear but have replaced them a few times over the years.

Damping at both ends is obviously critical!

Tony

 

[Shrek]

Hi Tony

Yep i agree with everything you have experienced.

I love that sound.

Totally agree with squared off rear tyres affecting handling.My bikes handle good with new tyres and slowly deteriorate as the rear tyre wears.I only realize how bad after i fit a new one.Somehow slips from my memory...
I also think a worn front tyre also adds to the problem to a lesser degree.I do notice some weird imbalance from the front to rear,just feeling out of synce.It then dissappears with with two new tyres.
I am fitting a Bridgestone Battle Wing radial rear and Pirelli Angel radial front next time to see how that goes?Conti Radials on my Lemons have transformed its handling.
Conti Classic attacks...highly recommended!

I think most older Guzzi,s also benefit from a fork brace.

Yes,i also prefer 34-36 psi front with 38-42 rear depending on which bike.

I agree about getting a good life out of steering bearings.but when my bikes start handling funny and the steering doesnt feel right.I change the bearings and there is always small vertical grooves in the bearing races.You can feel them with your finger nail and i believe these tiny grooves are often an overlooked cause of ill handling.
I now change mine at around 30,000 k,s or 5 years ish and always feel an improvement with sweeter steering and less wobbleing in higher speed corners.I just did the Cali,s and its much better to ride.
I was hoping this may help somebody out there who isnt happy with their bikes handling.
Or just a reminder for those of us who forget......

Adequate damping is a must.

Shrek

 

[Nordicnorm]

Glad I found this thread.
My '01 Jackal has occasionally suffered from this, especially as the front tire wears.
Adjusting the head bearings several years ago made a big improvement, but I think they had been left loose for too long. I also replaced wheelbearings, and checked forksprings for sag.
Time to follow your advice.
Can these bearings be sourced from the local bearing supplier, or are they a specialty Guzzi item?

 

[john zibell]

Glad I found this thread.
My '01 Jackal has occasionally suffered from this, especially as the front tire wears.
Adjusting the head bearings several years ago made a big improvement, but I think they had been left loose for too long. I also replaced wheelbearings, and checked forksprings for sag.
Time to follow your advice.
Can these bearings be sourced from the local bearing supplier, or are they a specialty Guzzi item?

They are standard bearings. The size numbers should be stamped on the race however I don't recall the size right now. Every bearing in a Guzzi is standard to my knowledge. Keeps manufacturing cost down. I replaced an upper frame on an EV some years ago. By careful assembly and paying attention to bearing adjustments she handled better than when new.

 

[Shrek]

As John states,they are a common bearing which can be sourced at a bearing shop.
The only problem is the bottom bearing usually needs to be cut off with an angle grinder,unless somebody knows an easier way than me?
This usually results in destroying the seal underneath it.
These seals are not as easily sourced.
While you can reuse a damaged one,try to find one or use none at all as i have done before.
To do the job properly i now purchase an aftermarket kit with two bearings and two seals from Allballs or another company which can be sourced on Ebay or bike shops.

If your headstem bearings are the originals,they will almost certaiinly have grooved races.

I usually wait until i need a new front tyre and change bearings while the wheels off.
While i am at it i usually rebuild the forks or replace the oil while they are out as well and check or replace pads and wheel bearings.
Then i know the front end is good for several years without having to do things seperately,coz i am lazy.

One more improvement i have done is to fit radial tyres to my Cali and Lemans.
The fronts improve steering response dramatically and aid stability a little.The rear mainly aids stabilty at higher speeds.makes leaning over more secure and gives me more confidence with handleing and improved feedback.
As GuzziGray says,His Conti Radials are night and day compared to the old rag rubber.
I am not saying crossplys are no good.I am just saying radials are better.

We dont have many to choose from in Tonti sizes but they are out there.
My Cali has
Pirelli Angel Gt 110/80/18R front
Bridgestone Battle Wing 140/80/17R rear
Lemons Has
Conti Classic attack 90/90/18R front Thats the only size 18 tyre they make unless you go to a 110 Road Attack.
Conti Classic Attack 120/90/18 rear
I highly recommend the use of Radial tyres on Tonti bikes.
My Daytona comes with Std Radial sized rims.

Good luck changing your head stem bearings NordicNorm.
P.S My daughter has just arrived here today from BC.
My partner is from Sayward along with a good friend whose shed is filled with Guzzi,s.

 

[Nordicnorm]

Thank you John,
A bit of "down time" here with the winter rains, so I'll get right at it.
It is my only issue with this bike, which has kept me engaged for longer than any other bike, any brand.
Here's to many more (s)miles....

 

[Nordicnorm]

Thank you Shrek,
We must have been typing at the same time.
I run BT-45s, and they are fresh, so they will be around (round?) for a while but they leave a little to be desired in the corners, so when the time comes, I would love to try radials. Never thought it was an option.
And yes, if you love Guzzis, Sayward is a "hot spot"!

 

[Shrek]

Bearing sizes 25x52mm tapered roller
Bearing No FAG 30205.inner and outer sometimes sold seperately.

This kit fits all Tonti models.

 

[Shrek]

My pleasure.
Ha ha,typing at the same time with family and friends from the same place.
Bt 45,s have been my favorite Tonti tyre for a long time.
As you say,they are quite good when new and grip really well.
However as the rear squares off and less so,the front loosing its profile has a very bad effect on handleing.
The dreaded Tonti weave.
My Lemans is almost totally devoid of any wobbles while cornering now.Except for some slight wiggles when hitting large bumps while fully leaned over above 160 k,s.
The Cali still has some slight wiggles above 120 under the same conditions.
But for the first time in 23 years i am finally happy with the handleing of the Lemans and the Cali is vastly improved.
Radials are now,definately a good option.When you get round to it

 

[GTM®]

I'll add/confirm all posted above. In addition to bearings and swingarm tension/bushings, geometry, suspension and tires will turn a decent Tonti, into an amazing one. Dropping the forks in the triples 20-25mm is immensely helpful to stability. Andrew fixed this with his de-raked frame.
I spent a decade perfecting my Jackal, though went overboard in the end with an inverted front end, V11 Sport wheels and crazy high $ shocks (Penskes highest offerings replaced the Ohlins). The result was a track day instruction machine that was a marvel to anyone who witnessed it. One handed stability at triple digit speeds, no steering damper. It's going to get a major refresh later this year.
As to stock rims: Saddest day is when Dunlop pulled the plug on the D205. The 205 was a police issue run flat, and an amazing tire.

 

[Nordicnorm]

Much good info here. Thank you guys.
2 years ago I lengthened the fork spring spacers from 80m/m to 92m/m. I could feel no noticeable effect or improvement, so back to stock.
Shrek, I was watching the "Tour Down Under" yesterday morning. Cuddly Creek and Corkscrew Road. I hope for your sake that you live in that area. Wow, nice roads!
BTW my front Originally Lazerteck, and later the BT45 (but not so much) has a history of cupping as they wear, aggravating the weave.
Could be a chicken and egg scenario, one leading to the other, but I am convinced my bearings have to go.

 

[Nordicnorm]

Todd, when I first joined here, you were offering "specially modified Jackal pegs, beveled for increased ground clearance".
I had a good laugh over that one.
Probably still in the old archives somewhere.

 

[Nordicnorm]

New bearings in hand from local spplier. I'll let you know.
Sometimes in the past I could ride with my hands off the bars, lately it starts in to a tank slapper immediately.

 

[Shrek]

I have an extra 13mm of preload added which is close to what you did.
I added preload to give me a little more travel since i have the forks raised 20mm.Although one mod probably negates the other.
Unfortunately i dont know those roads but i am close to the victorian high country which has dozens of amazing roads around the snowy mountains.So i am spoiled for good riding roads.
All of my crossply fronts,including Lazerteks and Bt45,s wore unevenly between tread blocks on both Guzzi,s.Fishscale looking wear.
You should see what a day at the track does do them.
Its normal.Small tread blocks deform easily under cornering forces.High pressures help a little 36front 42 rear.
Radial tread patterns generally have much larger area,s between grooves and suffer less.
I dont think you can ever cure this wear behaviour on crossplys
.RADIALS!
If you enjoy cornering enough,you can eventually make your own bevelled footpegs.Although it does slow your corner speed a little.

 

[Shrek]

You must have been typing at the same time again.
I hope it fixes your problem.

 

[GTM®]

Todd, when I first joined here, you were offering "specially modified Jackal pegs, beveled for increased ground clearance". I had a good laugh over that one.

Took a little digging but I found them...

 

[Shrek]

Ha
Are they still available for sale Todd?
Do you have a centrestand equivalant or do you modify your lifting technique once the foot tang wears through and falls off
I almost dislocated my knee yesterday when one of my new work boots got traction on the road and tried to stay there.

 

[GTM®]

Are they still available for sale Todd?
Do you have a centrestand equivalant or do you modify your lifting technique once the foot tang wears through and falls off
I almost dislocated my knee yesterday when one of my new work boots got traction on the road and tried to stay there.

Heh, sure. No center-stand, as I'd have been on my head more times then I can count. Road-race boots with toe sliders, and rolling your foot up (road racing habit) keeps it off the tarmac.

 

[Shrek]

I think its only a matter of time before the stand gets me.Heres hoping its on the low side.
Good advice.I underestimated the traction of my new work boots.
Balls of feet on the pegs today and alls well.
Hmmm...maybe i should remove it......thanks for the tip.