Ceriani cartridges?

Unfortunately the DPO put a Ceriani front end on the Norton and having recently got the old girl club rego'd and back on the road, I'm finding the front end is really not up to scratch. Lots of challenging hilly roads down my way that easily show up the limitations of a damper-rod fork. I've been thinking of gutting the forks and putting cartridges in them and wondered if anyone had any advice in this area.

Another bizarre thought was to experiment with making a leading-link front-end myself. "Earles" I believe is the common name for them, something like what used to be used on the old BMWs. I know you're going to ask "why" and the answer is, simply because I would enjoy the engineering challenge! Hell, the bike's far from standard, so why not explore such options further.

davamb said:

Lots of challenging hilly roads down my way that easily show up the limitations of a damper-rod fork. I've been thinking of gutting the forks and putting cartridges in them and wondered if anyone had any advice in this area.

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Fit a set of Lansdowne Engineering dampers: http://www.lansdowne-engineering.co.uk/three_3.html

Yup ! huge improvement, reasonable cost, good support !
Craig

davamb said:

Unfortunately the DPO put a Ceriani front end on the Norton and having recently got the old girl club rego'd and back on the road, I'm finding the front end is really not up to scratch. Lots of challenging hilly roads down my way that easily show up the limitations of a damper-rod fork. I've been thinking of gutting the forks and putting cartridges in them and wondered if anyone had any advice in this area.

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Dave - in the Ceriani forks, the fork tube is prevented from separating from the slider by the piston coming up against a register in the bottom of the tube, usually held in by a circlip and cushioned by a top out spring fitted under the piston.

If you fit Lansdowne cartridges, the fork tubes (stanchions) will be prevented from separating from the sliders on full extension only by the damper piston coming up against the underside of the cap on the damper cartridge. This may be sufficient in practice, but discuss this with John Bould if you decide to go this route. The hydraulic stop at full compression needs to be considered too. This would need to be custom made to fit snugly inside the bottom of the Ceriani fork tube and the bottom end of the slider. What does the bottom of the fork tube on your particular Ceriani look like? It might need to be machined so that it slides smoothly over the taper at the bottom of the damper cartridge on full compression. You will also need John or someone to make new top nuts with a fine metric thread.

So even if the cartridges may fit inside your forks, you will probably need an engineering shop to fit the cartridges to your forks to precise specifications… unless you post the whole lot over to England (!).

I remember comparing the internals of your forks with the ones that I had in mine in a previous post. I think that because yours are more primitive, I doubt Race Tech cartridge emulators would be worth fitting. If you could get some of the later damper internals with a rebound check valve, then Race Tech valves would be worth considering.

davamb said:

Another bizarre thought was to experiment with making a leading-link front-end myself. "Earles" I believe is the common name for them, something like what used to be used on the old BMWs. I know you're going to ask "why" and the answer is, simply because I would enjoy the engineering challenge! Hell, the bike's far from standard, so why not explore such options further.

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I have been thinking along the same lines. The inverted front forks on my bike work really well but I sure am tired of replacing fork seals.
Tony Foal front end.

Thanks for the feedback chaps, much appreciated. Yeah, I gouged out the wire C-clip some time back Dave and replaced it with a proper C-clip that I could remove and replace at my convenience. Last weekend I made up some adjustable pre-loaders out of some stainless coach bolts and nylocks. I've cut an M10 thread through the fork caps. They replace the spacer washers previously fitted when the forks were rechromed. The mod improved the front-end dive under braking somewhat and allowed the front-end sag to be setup. I still find the bike marginally unstable in some corners which I'm beginning to think is a result of there being no damping at the initial stages of the compression.





(Pardon the lazy cat...)

What I don't know is whether a standard Norton with Roadholders is any better - having never ridden another Norton! Perhaps I'm silly trying to punt it around like a modern bike and maybe I should just let it be. Could take away what makes it a classic in the first place. Just can't help thinking it should be better than it is!

Interesting piccy there Jim. More food for thought. Not being a suspension expert and being a long way from any one that is, a leading-link system might provide a lot of scope for adjustment. I'm thinking of knocking up a 3d cad model and seeing what comes out of that.

Got some 89 FZR 600 forks on my Commando Special , they work very well + the twin discs that came with them 8)

davamb said:

Unfortunately the DPO put a Ceriani front end on the Norton and having recently got the old girl club rego'd and back on the road, I'm finding the front end is really not up to scratch. Lots of challenging hilly roads down my way that easily show up the limitations of a damper-rod fork. I've been thinking of gutting the forks and putting cartridges in them and wondered if anyone had any advice in this area.

Another bizarre thought was to experiment with making a leading-link front-end myself. "Earles" I believe is the common name for them, something like what used to be used on the old BMWs. I know you're going to ask "why" and the answer is, simply because I would enjoy the engineering challenge! Hell, the bike's far from standard, so why not explore such options further.

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Maxton, in the UK, take these forks, gut them, discard all internals and replace them with top notch custom made internals. Most top level classic racers over here use Maxton front and rear.
Down sides are: not cheap, long lead times.
Can transform a bike though.

Earles[edit]
The Earles fork is a variety of leading link fork where the pivot point is behind the front wheel, which is the basis of the Earles' patent.[6] Patented by Englishman Ernest Earles in 1953, the design is constructed of light tubing, with conventional 'shock absorbers' mounted near the front axle. The Earles fork has a very small wheelbase change under braking or under compression, unlike telescopic forks. Their construction is much stronger than teleforks, especially against lateral deflection caused by hard cornering (as when racing), or when cornering with a sidecar.[6] This triangulated fork causes the front end of a motorcycle to rise slightly when braking hard, as the mechanical braking forces rotate 'downward' relative to the fork's pivot point — this action can be disconcerting to riders used to telescopic forks, which have the opposite reaction to braking forces ('brake dive'). Several motorcycle manufacturers licensed the Earles patent forks for racing motorcycles in 1953, such as MV Agusta and BMW Motorcycle, while other companies (such as Douglas motorcycle) used the Earles design on their roadsters or off-road machines. BMW is best known for their use of Earles forks, as from 1955 to 1969 they were featured on every BMW motorcycle.

davamb said:

What I don't know is whether a standard Norton with Roadholders is any better

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Probably not.

As Fast Eddie says, Maxton will make you some cartridges, but you could be without the forks for months and get a big bill, including the carriage to and from Australia.

Surely there has to be someone in Aus who can do a job on your forks?

daveh said:

Surely there has to be someone in Aus who can do a job on your forks?

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Not that I'm aware of - and I've had a decent search.

Snorton74 said:

http://www.cosentinoengineering.com/index_files/Page450.htm

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Thanks for that SNorton, I'll send them an enquiry, see if they have something off-the-shelf.

Query sent with all the pics I have of the guts. Be interested to hear what they have to say.

I once rode an R69S BMW. Under braking the front end would rise. The geometry on most bikes is set so that they are stable under brakes. I have strong doubts about the BMW with leading link forks. What happens if you brake when cranked over ? It is never so simple as just bolting on a set of forks, it takes virtually nothing to create a nasty bastard.

You can get race tech emulators for Ceriani forks. There are quite a few places in Aus who sell them and fit them.

However I used a place in Melbourne which I wouldn't recommend to my worst enemy. He was 'kin useless. Took ages and charged me for parts he didn't fit.

Thanks John, I'll look into them too.

BTW, DPO put Konis on the rear and I took them to a certain place not far from Westall station for an overhaul. Told the chappy when I wanted them back (a period of almost 2 months) and all seemed fine, indeed he seemed quite happy to chat on for quite a while. Rocked up on the due day during my lunch break and was treated with utter contempt. Had not even commenced the rebuild and what the hell was I doing in his shop without calling to say I was coming! Told him I needed them by close of business that day as we'd agreed and that I'd be back to collect then. He was seriously not pleased about this. Dunno if he actually did anything to them, the lower mount rubber on the LHS wasn't in great shape due to chain muck slowly degrading the rubber - that was returned as supplied. Would have imagined that was the first thing you'd attend to. Anyways, thought it was just me and that I was being a little too hasty about it all so I figured I'd give him a go with the forks. A month later I swung by to see how things were progressing - he hadn't even taken them apart to send the legs off for rechroming! Said I'd take them back and polish up the alloy bits and return them when I'd finished. Decided never to go anywhere near the place again.

Place that did the forks was up in Knox somewhere, looked a very professional business and did what I asked on time. Long way from where I am now, but perhaps worth another call.

davamb said:

Thanks John, I'll look into them too.

BTW, DPO put Konis on the rear and I took them to a certain place not far from Westall station for an overhaul. Told the chappy when I wanted them back (a period of almost 2 months) and all seemed fine, indeed he seemed quite happy to chat on for quite a while. Rocked up on the due day during my lunch break and was treated with utter contempt. Had not even commenced the rebuild and what the hell was I doing in his shop without calling to say I was coming! Told him I needed them by close of business that day as we'd agreed and that I'd be back to collect then. He was seriously not pleased about this. Dunno if he actually did anything to them, the lower mount rubber on the LHS wasn't in great shape due to chain muck slowly degrading the rubber - that was returned as supplied. Would have imagined that was the first thing you'd attend to. Anyways, thought it was just me and that I was being a little too hasty about it all so I figured I'd give him a go with the forks. A month later I swung by to see how things were progressing - he hadn't even taken them apart to send the legs off for rechroming! Said I'd take them back and polish up the alloy bits and return them when I'd finished. Decided never to go anywhere near the place again.

Place that did the forks was up in Knox somewhere, looked a very professional business and did what I asked on time. Long way from where I am now, but perhaps worth another call.

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I just looked at a map of Melbourne and it seems to be the same guy.

I sent my Marzocchi forks to him when I was racing in the Bears series ( and leading the vintage class).

He said it would be two weeks and took several months. I missed a couple of rounds of the series and lost any chance of winning it.
I ended up contacting the Office of Fair Trading to help get my forks back. I had fill up his inbox with hundreds of e mails to get him to reply to me.

When I finally got them back, he charged me for a pair of Race Tech springs but when I stripped them down again ( 'cos they were no better than before ) I found he had put my old springs back in.



I had a totally different experience at suspension improvements at Slacks Creek in Qld.

I called him and explained about my forks and who had worked on them. He asked me to bring the valves to him to look at. He then told me that I needed to drill an extra bypass hole and fit racetech silver springs onto the valve. He gave me the springs FREE and charged me nothing for the advice.

Hello John, Steve is a good bloke and has pride in his work.
Please say the name of the business in Vic to avoid, might save others the same waste of time and money.

Graeme

GRM 450 said:

Hello John, Steve is a good bloke and has pride in his work.
Please say the name of the business in Vic to avoid, might save others the same waste of time and money.

Graeme

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The place I used in Vic was Pro Mecha . I can't say bad enough things about him.

Can I ask what model Ceriani forks you have fitted on your Commando? I've got a set of 35mm GP Cerianis that I was considering fitting to a Commando special I plan to build (mainly coz they look fabulous). The 35mm Cerianis seem to be very widely used in classic racing, so I would think they should be workable on the street. I'm in Canberra (but please don't hold that against me!) and would be interested in hearing of anyone who could uprate the forks to make them more suitable/better for street use. Cheers. Bill