Author Topic: New tires become suspension rebuild+...(Monza) FAC update!  (Read 19803 times)

Offline Tobit

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Re: New tires become suspension rebuild+...(Monza)
« Reply #30 on: March 30, 2015, 03:37:49 PM »
Excellent pics and procedural write up.  Dang, I miss my Monza.

Btw, our dishwasher died and my wife knows that if I replace it, the cost will be about $25,000 for new disposal, sink, cabinets, lighting, wall removal, appliance relocation and flooring.  Can't just replace the DW...

Just get me started....
Roman, '86 LM IV

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Re: New tires become suspension rebuild+...(Monza)
« Reply #31 on: March 30, 2015, 11:30:53 PM »
SED, thank you for taking the time to document the Marzocchi Strada rebuild. ;-T  I've seen Marzocchi's document but was a little cloudy on a few points. I've have them on mine too; they're not leaking and still damping okay but probably overdue for a change of the smelly oil. What weight oil did you use?

I had some Golden Spectro 125/150 for mtn bike forks and checked the viscosity rating and it appears to overlap the 5wt oil (http://bmwmotorcycletech.info/ShockOilComparo.pdf) that was recommended on the Laverda site so I went with it.  The Marz manual says Engler 1.8, Art. 52.46 and SAE 5 so hope I'm close. 
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Online SED

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Re: New tires become suspension rebuild+...(Monza)
« Reply #32 on: March 30, 2015, 11:33:16 PM »
Excellent pics and procedural write up.  Dang, I miss my Monza.

Btw, our dishwasher died and my wife knows that if I replace it, the cost will be about $25,000 for new disposal, sink, cabinets, lighting, wall removal, appliance relocation and flooring.  Can't just replace the DW...

Just get me started....
HaHa!  We just moved and the new house has a DW - do I have to worry??! 
1983 LeMans III
1981 Monza
1947 Ariel Red Hunter
1939 Ariel Red Hunter
1937 Guzzi GTV

Offline Groover

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Re: New tires become suspension rebuild+...(Monza)
« Reply #33 on: April 06, 2015, 08:11:34 AM »
I'm loving this thread, thanks for making it. I have a few questions... If I just want to remove the lower front legs to get them powdercoated for example and replaced the seals and dust covers, is this the only step required in my case to remove them (while the rest is all still on the bike)? Will oil come gushing out, or is the oil contained within the dampers?




Also, what size Avon RoadRider did you use. Tubed or Tubeless Conversion done?, and what color powdercoat did you use? Looks close to the factory color...

Great job on all!

Thanks!
« Last Edit: April 06, 2015, 08:16:52 AM by Groover »
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Re: New tires become suspension rebuild+...(Monza)
« Reply #33 on: April 06, 2015, 08:11:34 AM »

Online Antietam Classic Cycle

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Re: New tires become suspension rebuild+...(Monza)
« Reply #34 on: April 06, 2015, 08:36:34 AM »
I'm loving this thread, thanks for making it. I have a few questions... If I just want to remove the lower front legs to get them powdercoated for example and replaced the seals and dust covers, is this the only step required in my case to remove them (while the rest is all still on the bike)? Will oil come gushing out, or is the oil contained within the dampers?




Yes, removing that bolt allows the slider to come off without disturbing anything else. Unless you've drained the oil first, it will come flowing out as the bolt is removed. There are two separate areas with oil in those forks: the oil (atf) that lubricates the slider and tube (this is what will come out) and the oil contained inside the sealed damper cartridge (should not come out).
Charlie

Offline Groover

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Re: New tires become suspension rebuild+...(Monza)
« Reply #35 on: April 06, 2015, 08:46:08 AM »
Thanks, then I will do this soon! To refill the ATF fluid/oil, I'm assuming that done from the top of the forks (the large aluminum caps)?

EDIT: Found it in the manual! Thanks again!!

« Last Edit: April 06, 2015, 08:51:07 AM by Groover »
1981 Moto Guzzi V1000G5
1987 Moto Guzzi LM1000SE, a
1987 Moto Guzzi LM1000SE, b
1980 Piaggio Vespa P200E
1980 Piaggio Vespa P125X
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1980 Vespa SI Moped
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Online SED

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Re: New tires become suspension rebuild+...(Monza)
« Reply #36 on: April 06, 2015, 12:06:21 PM »
I'm loving this thread, thanks for making it.

Also, what size Avon RoadRider did you use. Tubed or Tubeless Conversion done?, and what color powdercoat did you use? Looks close to the factory color...

Great job on all!

Thanks!

Hey Groover,

Thanks for the nice comments.  Charlie's got you set with removing the lowers.  You just need to have your powdercoater mask and plug the lowers so no blasting grit or powder gets inside.

The powder color is "Silverstone" - probably this: http://www.prismaticpowders.com/colors/PMB-847/SILVERSTONE/
It is bluer and darker than the LMIII wheels I was trying to match.  The LMIII wheel color looks lighter and yellower.  But it is a nice color and not glittery with metal flake. 

Guzzi left all paint off the outer lip of the LMIII wheels.  It would've been good to mask that lip on the Monza rims too because it is easy (very easy!  :() to chip the coating with the tire irons.

The RoadRiders are 90/90-18 and 100/90-18 (original size) with tubes.  They are a tight fit on the rims and impossible to seat the bead with normal air pressure so it would be good not to add powdercoating to the inside of the rim - so mask that too.
Cheers,
Shawn
1983 LeMans III
1981 Monza
1947 Ariel Red Hunter
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Offline Groover

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Re: New tires become suspension rebuild+...(Monza)
« Reply #37 on: April 06, 2015, 12:21:09 PM »
Great information, thank you. I made a note of it all!
1981 Moto Guzzi V1000G5
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Online SED

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Re: New tires become suspension rebuild+...(Monza)
« Reply #38 on: April 10, 2015, 09:42:47 PM »
FAC dampers on back order.  Word is a month away.  Ugh!  :(

So how 'bout them Guzzi dampers?  Might as well have a look.   :BEER:

Unscrew cap...


Cap fits nicely into rubber boot...


Pry out rubber boot with dental pick then pull with needle nose pliers...


Then pull out with needle nose pliers...  (looking a little cut up)


All the reachable parts...


Note that the rubber boot is deformed - especially at the "receptacle tip".  I think the way it is supposed to work is that the tip of the boot blocks the holes in the top of the damper (compression), but the deformation makes a poor seal. 



 
« Last Edit: April 10, 2015, 10:23:23 PM by SED »
1983 LeMans III
1981 Monza
1947 Ariel Red Hunter
1939 Ariel Red Hunter
1937 Guzzi GTV

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Re: New tires become suspension rebuild+...(Monza)
« Reply #39 on: April 10, 2015, 11:03:36 PM »
I cleaned the dampers out with light weight fork oil and decided they needed more damping so got 20w fork oil. 

I did a lot of pumping up and down on the piston and thinking more about how the Guzzi dampers are supposed to work...  (always dangerous!    :beat_horse)
and noticed that oil and air bubbles seemed to come up the center hole and returning oil went down the small outer holes.



The way the air bladder boot is made it probably only blocks the center hole increasing compression damping.  A benefit for suspension is that increasing air pressure in the boot during compression would increase resistance to compression - a (very small) increasing rate air spring.  The purpose of the boot is probably the same as the air bladder in the Marzocchi shocks - prevent air and oil from mixing and ruining the damping.

The boots were so deformed that they would not make a good seal at the holes and one was leaking oil and air.  Rationalizing  :pop that heavier fork oil would mimic air pressure in the boot, and that a leaking boot just takes up space for oil...  I cut the boots just below the top cap leaving a sealing ring for the top cap, filled the dampers with 20wt and cycled them 'til all the air was out, then filled the top reservoir about 1/2 full with the piston all the way down.  Pushing the piston all the way up increased the level in the reservoir to near the top but leaves a little air space.  Presumably (ahem!) air over the oil will be at 1atm full extension and pressurized about 4x at full compression.  Hopefully this will be OK.

So this brings up the question: what is so great about cartridge forks?  Why not use the whole fork as the cartridge with a large reservoir of oil and air in the stanchion (or slider in upside down forks) so it will build up little air pressure at full compression and put less load on the seals. (or is 4x atm not a big deal?)  It also has fewer parts because the cartridge duplicates a piston, seal and reservoir. 
1983 LeMans III
1981 Monza
1947 Ariel Red Hunter
1939 Ariel Red Hunter
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Offline kevdog3019

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Re: New tires become suspension rebuild+...(Monza)
« Reply #40 on: April 11, 2015, 06:10:02 AM »
I take it you want to know how a cartridge works differently from damping rod?  Short answer is the cartridge accounts for slow and fast internal pressures through a valve so you get an even feel for slow and fast damping. The older rod type which you have is an oil displacement type where the given holes in the system displace fluid (oil) while damping. Problem is that while going fast they are quite ineffective and you get a very stiff ride. At slow speeds there is time for the displacement to happen (think slow motion) and they sometimes feel rather mushy. It's a one size fits all to compensate for slow and fast and does neither end much service. A cartridge mitigates this with its efficiency.
« Last Edit: April 11, 2015, 06:38:34 AM by kevdog3019 »
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Re: New tires become suspension rebuild+...(Monza)
« Reply #41 on: April 11, 2015, 09:29:49 AM »
I take it you want to know how a cartridge works differently from damping rod?  Short answer is the cartridge accounts for slow and fast internal pressures through a valve so you get an even feel for slow and fast damping. The older rod type which you have is an oil displacement type where the given holes in the system displace fluid (oil) while damping. Problem is that while going fast they are quite ineffective and you get a very stiff ride. At slow speeds there is time for the displacement to happen (think slow motion) and they sometimes feel rather mushy. It's a one size fits all to compensate for slow and fast and does neither end much service. A cartridge mitigates this with its efficiency.

Thanks Kev,  ;-T  Don't know much about them so was thinking that the cartridge worked like the damping rod.  It must be possible to engineer the fork with a cartridge-like valve and reduce the duplication of parts - probably only for racers and weight weenies.   ;D
1983 LeMans III
1981 Monza
1947 Ariel Red Hunter
1939 Ariel Red Hunter
1937 Guzzi GTV

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Re: New tires become suspension rebuild+...(Monza)
« Reply #42 on: April 11, 2015, 09:55:05 AM »
A few more updates while waiting for parts.

Paint stripper results:


Sanded, masked and 1st coat with self etching primer:


Final results:


Also cleaned the speedo drive parts and found that the worm threads (top center) were quite worn.  This may have been caused insufficient lube and because its retainer - the brass bushing top right - had slipped out several mm.


The worm wheel is held into the casting by a pressed in stamping so just cleaned with solvent and packed it with moly grease.   


There is a rubber seal (not an O-ring) between the drive tang and the rest of the drive:


Had to crimp the mouth of the casting to hold the bushing, but the drive turns smoothly:


Hopefully this helps someone!
1983 LeMans III
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Online Chuck in Indiana

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Re: New tires become suspension rebuild+...(Monza)
« Reply #43 on: April 11, 2015, 10:46:32 AM »
 ;-T
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Offline kevdog3019

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Re: New tires become suspension rebuild+...(Monza)
« Reply #44 on: April 11, 2015, 11:44:05 AM »
Thanks Kev,  ;-T  Don't know much about them so was thinking that the cartridge worked like the damping rod.  It must be possible to engineer the fork with a cartridge-like valve and reduce the duplication of parts - probably only for racers and weight weenies.   ;D

I can't help you there, but I would say those forks aren't worth messing with as they are pretty low quality parts Guzzi used.  They flex like toothpicks and that's their biggest downfall, not the dampening IMO.  Put your front brake on and push on them back and forth (not up and down) and you'll see what I mean about why things wallow in turns.  An upgrade to better quality forks is the best thing you can do.  I did and it's HUGE how stable these little guys can feel.  It's the single best upgrade for rideability I found.
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Re: New tires become suspension rebuild+...(Monza)
« Reply #45 on: April 11, 2015, 12:26:04 PM »
An upgrade to better quality forks is the best thing you can do.  I did and it's HUGE how stable these little guys can feel.  It's the single best upgrade for rideability I found.

I hear you Kev,
The stanchions on my mtn bike forks are the SAME diameter!  :o  And it's a light weight cross country bike - about 350lbs less than the Monza!  If it were a downhill bike the stanchions would be bigger.

I do have hopes of finding a V65 and doing an engine/transmission/fork transplant into the Monza - someday!   :)

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Offline Muzz

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Re: New tires become suspension rebuild+...(Monza)
« Reply #46 on: April 11, 2015, 05:28:26 PM »
.  An upgrade to better quality forks is the best thing you can do.  I did and it's HUGE how stable these little guys can feel.  It's the single best upgrade for rideability I found.

What forks did you use Kev?
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Online SED

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Re: New tires become suspension rebuild+...(Monza)
« Reply #47 on: April 13, 2015, 11:10:43 PM »
Not sure if anyone cares about trying to make the original forks work on the V50III  & Monza, but with the FAC dampers at least a month away I thought it was worth a try.

As you recall from our last episode the air bladder was removed from the original dampers, then purged and refilled them with 20wt fork oil. 

Stanchions were cleaned out by pulling a rag through them.
 


Per Guzziology, the lower spring seat was dropped into the sliders with the its locating pin 180 degrees from the notch to receive it, then turned with a long screwdriver.  You can feel it drop into place.  If you have marked a line on the top you can also confirm that it points toward the notch which corresponds to the drain screw.



Then time to drive in the new seal:



Slather everything with assembly lube - use a long finger to wipe it on the aluminum bearing surfaces down in the in the slider:



Smear a thin layer of lube over the surface of the stanchion and insert.  Wear marks indicated the bleed hole had been at the front so turn it 180 degrees so it bears on a fresher surface.  (maybe just superstitious  ::))
 


Smear a little lube around and slide the dust seals over:



Assemble the spring on the damper rod.  Notches at the bottom retainer engage the notches in the lower spring seat to keep it from turning while tightening the lower retaining bolt:



Slather the spring and damper with assembly lube (more superstition) and lower it into the slider, then insert and tighten the bottom retaining bolt with its aluminum gasket:




Check that the lower bolt is tight and the drain plug installed and then fill the fork lowers.  There is very little room between the damper cartridge and the stanchion.  A large syringe (feed store item) makes it relatively easy to fill with the correct amount.  The oil goes in slow and needs time to drain down past the cartridge.  If you give a good squeeze on the syringe it will quickly overflow and drip on your shoes (ask me how I know!  :P).  Pumping the stanchion up and down encourages the oil to drain into the slider.



Pull the stanchion up out of the slider and screw the damper top into it - after lubing the threads and o-ring of course!

1983 LeMans III
1981 Monza
1947 Ariel Red Hunter
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Online SED

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Re: New tires become suspension rebuild+...(Monza)
« Reply #48 on: April 14, 2015, 12:05:26 AM »
Now time to install the triple clamps with their new ball bearings.  Tighten the bearings correctly, but don't tighten the pinch bolt in the upper triple clamp.



It's worth doing a test fit of the fork legs in the triple clamps.  Friction holds the stanchions in the clamps so nothing has to be tightened yet: 



By far the most tedious part is inserting the stanchions through the headlight bracket and clip-ons while routing the cables correctly.  It is worth marking every cable and wire bundle with tape to know whether it goes above or below the headlight bracket, and around or behind the stanchions.   I failed to do this and had to disassemble the twist grip/switch assembly to reroute the throttle cables.  Opening the grip/switch pod broke a wire off one of the incredibly fragile switches so now looking for a replacement.  Any suggestions?



I found there was plenty of room between the upper and lower triple clamps if I loosened the pinch bolt that clamps the bearing lock nut and raise the upper clamp as far as it would go (see arrow above).


The twist grip is impossible to assemble with two hands.  My solution is to clamp a vice grip over it to provide some tension while one hand puts some tension on the cables and the other two install the screws.  Works every time  :BEER:



Eventually everything goes together.  Install the axle and gently tighten the pinch bolts in the fork lowers to align them vertically, then tighten the rest of the pinch bolts and it's almost done! 



Ready for a test ride! 
1983 LeMans III
1981 Monza
1947 Ariel Red Hunter
1939 Ariel Red Hunter
1937 Guzzi GTV

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Re: New tires become suspension rebuild+...(Monza)
« Reply #49 on: April 14, 2015, 12:10:22 AM »
I would say those forks aren't worth messing with as they are pretty low quality parts Guzzi used.  They flex like toothpicks and that's their biggest downfall, not the dampening IMO.  Put your front brake on and push on them back and forth (not up and down) and you'll see what I mean about why things wallow in turns. 

Kev, Here's photographic evidence of the size of 375lb Guzzi forks compared to 28lb mtn bike forks - Yikes! 


Better clean up the mtn bike...  ::)
1983 LeMans III
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Re: New tires become suspension rebuild+...(Monza)
« Reply #50 on: June 14, 2015, 02:06:39 PM »
FAC dampers finally arrived and have been installed - WOW!   :thumb:

The whole bike feels more "planted" on the road and is much more confidence inspiring on old uneven concrete.  There was a big improvement after the rear shocks were rebuilt, but the new dampers are great - what fun!

Compared to the original dampers the FACs have much better rebound damping and very little compression damping (no air).  Divots no longer jar the bike, and the uneven road surfaces in corners are not very noticeable.

I used Antietam Charlie's method for replacing the dampers and it took about 1.5 hours.

Block up sump and pull dampers from the stanchions.
 



Pull pinch bolts and axle, drain oil from one side then pull the lower fork bolt on that side:



Pull the damper and spring assembly out and swap dampers: (FAC top)



Insert new damper spring assembly into fork leg, rotate until notch in spring retainer seats in the bottom of the fork leg and re-install lower fork bolt.  At this point the manual suggests you dribble fork oil down into the leg between the damper and stanchion - this is tedious and messy and time consuming.  Instead use a syringe with a fat o-ring or piece of vacuum hose (see pic) over the nipple and inject the oil into the drain hole.   Finish filling from top if necessary.
 


Back from test ride:



1983 LeMans III
1981 Monza
1947 Ariel Red Hunter
1939 Ariel Red Hunter
1937 Guzzi GTV

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