Anterior fork tuning

D

dr. bones

New member
Location
Roma
Hi to all, I have a sf1 Laverda with Ceriani 35mm forks and I would like to change these with  modern forks with a double disks braking system, is this operation possible twithout excessive technical difficulties?
And can someone tell me if there are forks models that can fit easily?
thank you
 
I found this special parts, can I use these alternatively?
https://store.bevelheaven.com/Chassis-Suspension/Fork-Leg-LEFT-HAND-PAOLI-35mm/
https://store.bevelheaven.com/Body-Dress-Up-etc/Forkleg-35mm-Paioli-Right/
 
I'd encourage you to leave the bike as it is. Those old drum brake Laverdas are classic. Sell it to someone who appreciates them as they are and buy a SF2 or SF3 that already has disk brakes. The rest of the bike is very similar.

But if you decide to go ahead with altering it, I'd suggest the easiest option would be to transplant a set of 38mm Marzocchi or Ceriani forks and triple clamps (with disk front end) from a later model (SF2 or 3). Laverda triples and Ducatis of the early-mid 1970s used similar front ends with 38mm forks, wire wheels and disk brakes, but you'll have to check that the triple clamp offset is OK. You could end up with money in your pocket after selling your drum setup. There are drum brake Laverda enthusiasts who would sell their children to get their hands on a good drummer front end.

PS: Welcome to the forum. Give my regards to Spock and Captain Kirk  :D

 
Sort of like this Dr Bones?

880SFCK%20Progress%20001_zps0uz3pios.jpg
 
dr. bones said:
Hi to all, I have a sf1 Laverda with Ceriani 35mm forks and I would like to change these with  modern forks with a double disks braking system, is this operation possible twithout excessive technical difficulties?
And can someone tell me if there are forks models that can fit easily?
thank you
Click to expand...

after Breganze Laverda went under, then production of a "new" line of Laverda's began that lasted several years, ending around 2001 (?), known as Zane Laverda's. The Zane Laverda's have top flight suspension and brakes, and I know several older Breganze Laverda twins have had complete Zane Laverda modern front ends grafted on to them. Worth looking at.

the one such conversion that comes to mind is Chris Haerter's 750, from Columbia Car and Cycle in British Columbia, Canada.  www.laverda.ca

I hate drum brakes myself, but many here will freak out over someone switching to disks from drums, as the early drum brake bikes have really been climbing in resale value.

Paul LeClair
 
Front end is 46mm Suzuki SV1000 and calipers, wheels are Duca:-X Sport Classic 1000 with stainless spokes and rear rim changed to 4.5" to fit a 160 tyre and offset 10mm when laced to get the correct chain run. So, 17" x 120 front and 160 rear.
Brakes are Metalgear 310mm. Rear brake setup is ZZR1200 with a spacer that I made up to suit the SV1000 Metalgear rotor.

Front end was an easy swap except for the top bearing. That headache lasted weeks, correct ID & OD bearings just weren't available. So I turned down the SV1000 bearing race OD over 22,000,000 beers and a similar amount of lathe tips.

I'm talking to Boba about using carbon Zane front guard, drum brake SFC tank, seat and fairing.

Red did the motor: 880cc Andy Wagner kit and all of Reds tricky bits (and a lot less crank) inside, not forgeting to 270deg twisted crank, and Ignitech ignition.

Finished to top engine mounts and am almost ready to weld up all the bracketry, paint frame and wiring.



 
 
Hi Chris

sounds great, looks fabulous!

a note. Having owned and ridden an 8000 series SFC 750 drum brake for several years, I hated that bloody tank. Too wide and sharpish at the back, bites into your inner thighs.. If you really want an SFC tank, think about the later and more slender tank, your thighs will thank you.

I am assuming that pretty much any modern fork upgrade is likely going to require going to 17 inch wheels front and rear, but gives a much better choice of tires ;)

Paul LeClair
 
Paul LeClair said:
Having owned and ridden an 8000 series SFC 750 drum brake for several years, I hated that bloody tank. Too wide and sharpish at the back, bites into your inner thighs..
Click to expand...

Yes, I already have one, but I have a major issue with the forks hitting the tank on even part lock.
The earlier one will fix that, I believe.
 
Hi Doc Bones
My Sf1 lost its drum brake in 1975 or thereabouts. Several yars with a coupe of nice TZ Yamaha 4 leading shoe monsters, but unfortunately too fragile for extended use (even on the original 250/350 racers). I was lucky enough to score motoddrob's old 35mm Ceriani disc lower forf legs (the first SF2 had 35mm forks) and made up a wheel from a Guzzi hub and Duke 860 4-bolt cast discs and std 08 Brembo calipers. From there I went to Marzocchi 38mm forks and 08 calipers, then M1R 38mm with goldline 08s. Hated those forks and went Japanese - I've since had a Honda VFR750 41mm Showa front end and triple clamps (easy mod to fit them) with the 08 gold calipers (easy fit with home custom adaptors), still on stock SF2 hub and 280mm discs. Then to early Suzuki GSXR-750 forks and triple clamps (also easy fit) with 4-pot Tokico calipers ... nice front end but a bit short with the 17" wheels I have since  fitted (stock SF2 front hub). Money was always an issue so there's been lots of experimenting with good and plentiful 2nd hand stuff.

Now in the process of fitting a Kayaba fully adjustable upside down forks and clamps from a Yamaha YZ750-RR with Yamaha R1 calipers (almost a straight fit) and 320mm Brembo discs from a 916-99? Ducati - will be machining adaptors for these - quite a big job.

ChrisK, I have had practically no probs with top bearings (easy to machine down the top of a stem or sleeve it, but not so the bottom). Have hit a snag with the big Kayabas as the lower bearing is 35mm ID ... will need to extend the head tube and allow for larger OD ... may even make up a new head tube. I could sleeve the bottom clamp and reuse the Suzuki stem but want the length that the longer head tube will give me. My bike just got lower and lower with every mod I've made and I need to get it back up off the ground again!! BTW, what is that swingarm in your pic? I have a chunky Yamaha FZR1000 Deltabox one in the shed, but think it's too much hassle and will stick with the stock SF steeler for now. And your shockers? What be them?

Dr Bones, basically you can get all sorts of alternatives and make them work. If you want 'originality' go the stock Ceriani SF2 setup - they are excellent forks, top notch. I like Paul's idea of the Zane front forks, but really you can find a load of stuff that will work - stick with the 18" wheels and try to get the length close to the orig SF1 (you can machine up extender fork caps and get an inch there - I mount clipons atop them, a-la RGS and many other modern bikes - ergonomically very very good. Agree that keeping the drum is great for resale - store it away but fit twin discs and enjoy real braking while you spend years thinking about how you'll never sell the bike  8) You can easily convert back.

I virtually gave my drum brakes away, the SF1 and the two TZ Yamaha 4ls's - worth a small fortune they would be now, but I have no regrets - I want to ride my Laverda and have never seen it as a collector's item - it's my bike!
 
Piranha Brother 2 said:
will be machining adaptors for these - quite a big job.

I have a chunky Yamaha FZR1000 Deltabox one in the shed, but think it's too much hassle and will stick with the stock SF steeler for now. And your shockers? What be them?
Click to expand...

To fit the Duca :-X front hub to the Suzuki forks, I had to machine up two 7.5mm spacer/adaptors as well. It took a while to work it out but Mark 2 worked fine.

The swingarm is an FJR1300 item. I shortened it by 120mm at the front. Too much hastle, I agree, but when I did it I had more time on my hands. I was tempted to make up my own chunky steel one from 42mm tube, but reading Steve Battisons account of making his own swing-arm, I feared it would stretch my patience. I may even have a go once it's on the road.

Shockers are NOS S&W's that I had tucked away from when I had more hair.  :o

Bones, I actually like the convensional forks. I have 10 weight oil in them, but they are way to hard for the road and will experiment with my own concoction, I'm thinking 7 weight, but time will tell.

I have no problems with a few subtle modifications and am in no way a purist, though, if I had an original SFC I could be swayed.  ;)
 
chrisk said:
I have no problems with a few subtle modifications and am in no way a purist, though, if I had an original SFC I could be swayed.  ;)
Click to expand...

Hi Chris

for the several years I owned the SFC 750 8000 series drum brake I treated it like I do my other motorcycles, rode it hard, rode it often, rode it in the pouring rain, etc., etc. However, after a full restoration and even converting the front brake to an era acceptable new old stock Ceriani four leading shoe brake still left me wanting more stopping power, and the riding position was bloody unbearable for more than a couple of hours. As its financial value and "collectability" soared, I had John Wilson of IIS build me one of the very few ignitions he did for 750 twins, added Pertonix flamethrower coils, took off the crappy Amal's and fitted 36 mm Dellortto's, swapped one crappy front drum brake for a slightly less crappy front brake, then began plotting to swap on a dual disc front end, carve up the stock original fiberglass fairing to be able to raise the bars, etc. At that point, and just before I was going to take a Sawzall to the precious original bodywork, Wolfgang kind of read me the riot act, borrowed the bike for a few weeks to measure and photograph as it was so factory original other than my limited modifications, then suggested I might be happier if I moved the bike on to a real collector who would undo my so far minimal and reversible modifications and preserve the bike in it's originality. I took Wolfgang's advice and sold it. Piece of motorcycling history, but what a horrible bike to ride on the street for any period of time or any real distance, all due respect to Rob Berryman and his later SFC of course...... On the other hand, the bloody thing shook the ground, the exhaust pulses hit you hard you in the chest from 20 feet behind the bike when it was idling, and that awesome, awesome sound........ I don't understand collectors who don't run their bikes :o :o

Paul LeClair
 
You had absolutely the right idea, Paul, but Wolfgang's advice was very good; just the wrong bike for what you actually needed - and simply too rare and valuable to fork around with. To be honest, you can build a better handling, more comfortable, faster Laverda twin out of an SF anyway - building SFC replicas is all good fun, but you still end up with the kind of bike you describe. You can even get the same noise and boom from a well fettled SF ... and then some! Ask Steve Battison  :D

I've now got enough stuff for two SFs, one I'll continue to heavily modify and experiment with, the other I'll probably build as a less modified allrounder. But ... I could never live with several issues on stock SFs (drum front brakes being #1) and will always 'modify and ride' ... simple things like light clutch (yes and I WILL cut the groove in the selector cover!), quick action throttle, lighter carb springs, no junction box (sorry Piet  8)), laid forward shocks.

Quentin
 
I find the Dam conversion overly light and lacking in feel when letting the clutch out. Went back to the original clutch arm and it gave a much better feel. Not a fan of the other type of extension either but then I have no issue with standard clutch pull on a properly maintained system.
The clutch action on POP is similar to the feel on the Corsa, the only change on both is a modern dog leg lever ratio, much less obvious than cutting a slot in the sprocket cover or having a series of angled bends exiting the inspection hole.
 
Hey Quentin, I got your email, and have been mulling over what you asked, I'm not ignoring you. Just trying to get my thoughts together, before putting them into written words.
 
Cool nanas, Chris. I actually thought my PM must have dissolved in the ether cos I couldn't find a copy in my PM Inbox. Good to hear you did get it. Look forward to a good read. Don't worry, I'll have yet more questions to hit you with  :D
 
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