Ducati.ms - The Ultimate Ducati Forum banner
  • Hey Everyone! Enter your bike HERE to be a part of this months Bike of the Month Challenge!

1 - 15 of 15 Posts

·
Registered
Joined
·
29 Posts
Discussion Starter · #1 ·
Has anyone come across a drop in cartridge/spring upgrade for our old 38mm forks?

I know a few bevel racers are using modified Japanese cartridges with great success but they also have access to specialised machinery and skills.

Any clues out there apart from Race Tech Gold valves etc?

Cheers
Chris
 

·
Registered
Joined
·
29 Posts
Discussion Starter · #3 ·
Thanks, I already have. He thinks the cartridge setup is restricted by the dimensions of the tubing and suggests using the RaceTech setup on a 'bang for buck' basis.

I'm wondering what others on the other side of the pond think or have done.

Chris
 

·
Registered
Joined
·
2,447 Posts
Maxton in the UK fit cartridges to these forks, but there is some work to be done. I think most of the calssic racers use their forks.
 

·
Registered
Joined
·
29 Posts
Discussion Starter · #5 ·
Yes and they're very good from all accounts. Just a bit expensive.

I know of one racing Ducati in Australia that uses Honda VTR cartridges and another one using another Honda type. There's probably more.

I'm wondering if anyone has done any modifications to their road bikes either by paying a shop to do it or actually done it themselves.

Cheers
 

·
Registered
Joined
·
256 Posts
i fitted sliding bushings to a 38 mm Marzocchi to eliminate stick slip .
honed the inside of the bottom slider to 39 mm and machined room for the top bushing .

i used Kayaba parts from a Yam and Kawa
fork tubes are Yam FZ 600 and have some internal valving for compression
damping . i made up aluminum damperrods out of 6061 alu and had them
hard anodized

my brother did the same thing and fitted a cartridge from a Honda 600

Eldert
 

Attachments

·
Registered
Joined
·
29 Posts
Discussion Starter · #7 ·
Eureka, now we're gettin somewhere. You're a legend Eldert.

A few questions:

How hard was it machining the bottom of the slider and did you have trouble finding someone with a long enough mandril?

I take it you used Yamaha internals?

kawasaki bushes?

which Honda 600? Just in case I come across one instead of the other.

was it much mucking around mating the Jap stanchions to the slider?

and what did you use for fork caps?

Fantastic
Chris
 

·
Registered
Joined
·
256 Posts
Hi Chis

i use Marzocchi top caps , i had to shorten the Yam forks and cut Marzocchi treads in them on the lathe . for the aluminum demperrods i used the Kayaba pistonring . i found a guy that has a shop that specialises in honing , he has a big machine that goes up and down by itself . he made a jig to hold down the bottomsliders and mounted that to the machinebed . al he has to do is give the mandrel a few clicks so it expands and there goes the machine again . the bottom slide bushing you can get from Yahaha . for the top one Kawasaki is the supplyer

for the cartride i think i was from a Honda 600 from around 95/96
( my brother is on vacation , cant ask him )
but there are plenty more cartridges that should fit

we did a lot of 35 mm forks like this . here is a picture of a internal valve of a 35 mm Showa fork from a Yam RD 350 . the other picture is of a damperrod i made to mate a Ceriani bottom slider to a Honda NSR 125 fork tube

Eldert
 

Attachments

·
Registered
Joined
·
29 Posts
Discussion Starter · #10 ·
Eldert,

I can't thank you enough for sharing this.

This is particularly helpful for those of us who still ride, tour and thrash our bevels.

I'm on the hunt for bits now.

Cheers
Chris
 

·
Registered
Joined
·
26 Posts
I know exactly what you should use. I just don't know if you can get one. I roadrace in AHRMA, and I use a 38mm Marzocchi fork. Pierre Vaillancourt at Works Performance made me a custom cartridge insert for these forks that works perfectly. As good as any modern fork. Not sure he is still making these, however. This is sort of major surgery, not a simple drop in part like an Emulator, but the result is peerless.

And the fork springs I use on this bike are Works Performance dual rate springs, with an adjustable crossover--meaning it can go to the higher rate early, or late, in the travel, depending on what you want. The bike is light so these are 40-60 lb rate springs, but I think for a 400+ pound street bike, you will want heavier springs, so ask Pierre.

The alternative is to take the guts out of F3 or F4 600 Honda forks and graft them inside, then get springs to fit, but that is even more major surgery.

I use Emulators on the other, much lighter bike I road race, and they are good in that application, but these are really good on the heavier bike.
 

·
Registered
Joined
·
26 Posts
Is there a reason why you would not wish to use the BevHev Racetech cartridge kit?
Not sure I know what a BevHev Emulator is.

I do know that I raced at AHRMA Miller a couple weeks ago, and in the right hand "Satisfaction" turn (the second of a double rank right), the race cars had put bad chattery little bumps all the way around. On the bike with the Works Performance cartridge dampers in the 38mm Marzocchis, it tracked through it so perfectly I didn't notice those bumps were there. On the bike with the Emulators, 38mm FZR 600 forks with Emulators, pretty analogous to the Marzocchis, I had quite a chatter--enough to change where I rode and how I used the gas. Now, I get help from Matt Wiley at Race Tech and they are great guys and their product is really good, and I have just converted this bike over to 38's and Matt and I haven't yet gotten the chatter tuned out of it, but hey, I am just telling you what I experienced, and why I said what I said above. Direct comparison, same corner, same day, same rider.

And they were both good--no rap on the Emulators, I just don't have them completely tuned yet--I won races on both bikes.

I just bolted up the Works cartridge inserts (with some machine work) and they have worked perfectly. The Emulators may need some tuning. I suspect you will have a much easier time dialing in the Emulators with a heavier bike, my little 250 lb, 430 cc 70 hp Yamaha GP bike is really sensitive to Emulator settings; on the other hand, my street Darmah SS is almost 500 lbs, and my guess is, the Emulators will be easier for you to dial in on a heavier bike.

And, you should also remember, the Emulators are going to be much easier to put in, it only takes a drill and some wrenches.

On the other hand, I ride the heck out of my bevel twin on the street, and I never noticed the damping was a problem like I do on my race bikes, I just don't go hard enough on the street for it to matter. Here is what I did to the stock street bike: Stock damping, 20 wt fork oil (don't go lighter than 15, it will wallow and chatter), the oil level set 5 1/2 inches from the top with the springs out, 1 3/8 sag or so, and heavier Works fork springs is all I use on the street and it works fine. You might start there with just oil and new fork springs--the stock springs were so soft they made it misbehave and the stock oil level was so low it didn't have enough anti-dive--and changing only springs is a lot cheaper than damping changes to start with--but if you do decide later to change the damping, you will need the springs anyway, so no loss to start with springs, and oil.
 

·
Registered
Joined
·
13 Posts
Sorry about the shorthand ... I was referring to the Race Tech Gold Valve cartridge emulator sold by Bevel Heaven, for 38mm Marzocchi and Ceriani forks.
 

·
Registered
Joined
·
26 Posts
I figured that out later, sorry. Only thing I would say is, if you buy from Race Tech or Matt he can then help you dial it in, by phone or whatever. He is quite good at this. But then for the street try getting it working right with stock daming first, by changing springs and using the right fork oil viscocity and level, you might be surprised. If not, you will need the springs anyway for the Emulators.
 
1 - 15 of 15 Posts
Top