20 replies to this topic

[philippe7]

I would like this thread to be a point of discussion about Rudi Kurth's extraordinary creations, and as an aside about the various Yamaha 3 cylinders machines, a concept in which Rudi's major imput is well documented. To start off with I collected as many posts as I could find on the subject in various TNF threads, and quoted them below, in an effort to bring them together and hopefully trigger off new discussions - specially since we are fortunate to have Dane Rowe on board now and hopefully she'll kindly take some time to add her first hand knowledge .

I realise Dane has her own dedicated "fan club" thread but I thought , for the sake of clarity and the benefit of potential researchers, that it would be better to have a separate thread carrying Rudi's name in full, and more oriented on the technical aspects of his career. However, if Twinny or others on here feel it would make more sense to merge the two threads and alter the thread title, please feel free to do so .

Here goes, then, in chronological order ( starting in 2004 ) .....

Edited by philippe7, 23 May 2009 - 01:15.

[philippe7]

Rolf Biland was indeed the first one to believe - and to win - with the " monocoque + whishbone" chassis , but I think that must have been in 1975 actually - he won the Deutsch GP at Hockenheim .

But the original "creator" of the concept was another Swiss maniac , Rudi Kurth , who had built such a chassis ( with a home made triple based on a 350 TZ with an extra cylinder ) quite a bit earlier.....but with no success, due not to the concept but to engine unreliability. Kurth was a real visionary in many ways , he had introduced the concept of very "low chassis" with wider wheels than the German's BMW kneelers quite before that , and had also equipped one of his outfits with a swedish Crescent outboard engine , opening the ways for the 2-strokes in sidecars for König then Yamaha ......

Dane Rowe NEVER "leaned out" of the chair. Rudi Kurth's inventive monocoque (WAAAAAY before the Seymaz and LCR) chassis was designed so that the passenger was just that, a passenger who was no longer involved in weight distribution. The first time Rudi and Rowe raced the outfit (Clermond-Ferrand in 1967 if I recall), it absolutely SHOCKED the public. It took him a while and several re-designs of the 3-cylinder Crescent-based, water-cooled two-stroke boat engines until he finally was competitive, but the basic design stayed the same and was then imitated by others. Kurth WAS the guy with all the ideas. Other followed.



But the actual very FIRST monocoque Rudi (or anyone else in sidecar racing ) built was a BMW-powered outfit in which I had the privilege (?) of being the passenger. Built of welded sheet steel, it was very light and extremely efficient. Driven by Frenchman Brejat, we won several hillclimbs with the thing and never got off, thanks God, making us some decent cash! Below is a relatively still young T54 (his nose still up in the breatheable air ) in the Rudi Kurth-built outfit, bearing the same Cromwell helmet I wore during most of the 1960's, before I discovered the greater safety of the Bell Star.



Regards,

T54

Bonjour T54

So my memories of Rudi Kurth were not too misty.....however, if he did build the first ever "monocoque" with BMW, then Crescent engines , those were still "conventional" ( ie Earles fork ) suspensions , weren't they ? I think his first design with the triangular car-like suspension was with the TZ Triple engine, in 1975 maybe ( French GP , Paul Ricard ? )

Oh, and is your friend driving the sidecar the same Dominique Bréjat who todays appears in historical bikes meetings in France with various exotic machinery , and who also is ( was ) chairman of the TZ 250 fan club ?

Yes indeed, his first chassis used a steel sheet fabricated modified Earles front suspension system and 3 10" X 7" Mini-Cooper alloy wheels with Dunlop CR65 tires. This advanced outfit had a kneeling position, a fairly recent development then. This when Max Deubel was still world champ with a "sit-down" style RennSport sidecar with 18" motorcycle tires.


T54

Edited by philippe7, 22 May 2009 - 22:38.

[philippe7]

Thank You Macca . yes, there were plenty of "extended" Yamaha's , either 350's ( based on a 250 Twin ) or "500's " based on the 350 twin ;

I have read an interview by Ferry Brouwer, who created the Katayama (and Agostini) triple , who readily admits that the original creator of the concept was Swiss sidecar ace Rudi Kurth , who had been the first one to make such an engine , around 1974/1975. Of course he built it primarily to be put into his side-car outfit , but also fitted it in a solo frame : I perfectly remember visiting the Paris "Racing Cars and Bikes Show" , must have been end of 1975, and I noticed this stange Yamaha triple , and since Olivier Chevallier , who was organising the show, happened to walk down the aisle at the same moment, I was cheeky enough to stop him ( first time I ever spoke to a Grand Prix rider ! ) and ask him what it was , and he kindly explained the bike had been loaned by Rudy Kurth.

Fenchman Christian Bourgeois also later built a Yamaha "500" triple , which he called the CBR ( Christian Bourgeois Racing ) and fitted into a Moraco monocoque.

A warm welcome from France to Rod Scivyer !

Now maybe at last I am going to get the answer to something that has been puzzling me for years ! Rod, were you not associated with the "lowboy" Crescent/Monark 500cc GP racer that was built by Rudi Kurth , with the same ( ex-powerboat) 2-stoke triple that he used on his sidecars ? I remember a picture in "L'Automobile" of the launch of the "revolutionary" bike , with Kent Andersson sitting on it but the article was stating that the development was to be led by a certain Rod Scivyer.....I must confess I didn't know much about you at the time, but the name definitely stuck to my mind......is there any thruth in this story, and could you tell us more ?

Hi Phillipe and thank you for the welcome.

I did work with Rudi for a while and whilst with him I had the opportunity to ride the solo at the French GP at Paul Ricard.
It used the same engine as the outfit but suffered cooling problems due to the somewhat limited space for a radiator compared with the sidecar version. This lead to several exiting moments on the Mistral Straight when the cooling system reached bursting point and relieved itself through the radiator cap straight up under the screen and back into my face, the resulting steam cloud rendering me temporarely blind whilst flat out The wheels were six spoke Offenstadts with three spokes removed Due to its light weight and extremely low build the handling was superb, but the brakes, which I believe were Dunstall, were hopeless. The rear suspension was catilever using a modified Citroen car unit much the same as the three wheeler. The workmanship, as with all Rudis project was superb.
With further developement I think it would have been quite successful. Unfortunately the pressure of Rudis GP campaign and the fact that I left prematurely to join Kawasaki meant the end to my involvement.

[philippe7]

Doesn't the Scitsu look lovely? I have to confess I know very little about it. Anyone know of any info sources? One of a number of TZ threes, though I've not heard of the Zegers. I think the Katayama 3 was 'semi' works in as much as it came out of the Yamaha NV shop in Amstelveen, Holland, rather than Japan, Trevor Tilbury being the impetus behind it. One of the earliest was Rudi Kurth (sp?) who put his in a chair named the Cat. Dennis Trollope was also an exponent. One of the reasons that its a relatively simple creation is because the standard TZ crank has centre flywheels with a helpful 12 splines, making the creation of a 120 degree crank simple (I think!). Sorry for long post.

Chris

Nevertheless the "special triples" topic is also a fascinating one, it is now fairly broadly admitted ( on the continent at least ;) ) that Rudi Kurth was the first one to experiment with that for one of his sidecars CAT outfits in 1975 (?) - but also on a solo bike, I perfectly well remember spotting this very strange looking triple TZ at a "racing car and bike show" at Paris , must have been.... January 1976 maybe ? and as I was really wondering what the hell that was , here comes walking down the aisle none other than Olivier Chevallier, who was in charge of the "bike" part of the show... and I cheekily went up to him and asked him what it was , and he told me it belonged to Rudi Kurth ( first time I ever spoke to a Grand Prix rider I suppose )

Anyway, after that the Katayama - Ferry Brouwer World Championship winning special is fairly well documented, in France Christian Bourgeois also experimented with both a 350cc ( 250 Tz +1 ) and 500cc (350 Tz + 1 ) in Moraco-Droulhiole monocoque frames , that he called the CBR's .

However I'm surprised to see that Dennis Trollope tried the trick as early as 1975, that was almost contemporary with Kurth then , we could have an interesting piece of research to do there , who was first ?

[philippe7]

Here it is, October 1974.
I am pretty sure that Ted Broad had one in 1972/3? when Chris logs on I expect he can tell us!

Photo copyrighted to Graham Etheridge, racebikepics.

You are right, Graham. He first built his three in '71. I think it first raced in '72 as a 521cc. John Chisnel in Chelmsford built an aluminium monocoque chassis which it was housed in in '73 (i'm sure that frame has been in a pic on this forum, but it would just take too long to find it!). In '74 it was back to the good old twin loop frame - which was actually a road frame from a Yam YDS7, with a front wheel and disc from a road XS2(I posted a picture a couple of weeks ago of Ditch on it on the front row of the john player international at Silverstone). The final incarnation was in a too heavy TZ700 frame in '75 with Dave P on board. I still have the crankcases and various other bits of it in the shed.

Philippe, I certainly recall rudi Kurth's CAT being around at a simialr time, and remember my Dad having long conversations with him (seem to remember in the Assen paddock in particular) about how to make the thing work!

Chris, Rudi Kurth's first "CAT" outfit was powered by a Crescent 3 cylinder based on a powerboat outboard engine . He used that in 1974 and the chassis , although a very low monocoque , still kept the basis of the "classical" sidecars i.e a front "earles"-style fork . The later "CAT" outfit that I was thinking of was a totally different design , with just a central piece with the three wheels attached by triangular car-style suspensions....that was the one fitted with a Yamaha triple, he used it in 1976 I think....I would need to dig deep into my old magazines to set things straight in terms of chronology, I'm not certain now who first experimented with car-style suspensions on the sidecars, Rudi Kurth, Rolf Biland with his first Seymaz , or even for you Brits the Boret brothers with their Renwick König

Anyway, to come back to the original topic, from what you are saying Chris it does appear than the earliest Yamaha triple experiments indeed took place in Britain....you always learn something on this forum !

[philippe7]

Recently there was a bit of chat regarding the 3 cylinder Yamaha projects that were undertaken in the 70´s. I was researching something today and stumbled across this site. It might be of interest. Unfortunately, it´s in Dutch, so for us non Dutch speakers, a bit difficult to follow, but there are some wonderful pics which will be of great interest I am sure. Enjoy.

http://home.hetnet.n...kes/triples.htm

That's a brilliant find, thanks a lot ! Most of the projects we discussed are there ( except the British ones ;) ) and I'm happy that there are pictures yo illustrate what I was trying to explain re. Rudi Kurth's sidecar project - however the Yamaha triple machine is only in the "paddock" shots , the "track" ones are both from the earlier Crescent-engined CAT .

Right on the nail again Fu. I met him ( edit : Philippe Coulon ) when I was working in Switzerland '75 for Rudi Kurth. Late one night he turned up at Rudi's place and wanted to borrow my transporter to get to Imola as he had blown his up. Rudi took me on one side and told me to think very carefully before agreeing as he had blown multiple transporter engines!!!. I wanted to help so we came to an "arrangement" and I drove him to Imola. Whilst there the UK Kawasaki team had a major disagreement in their team personnel and I was approached by Mick Grant and asked If I would join them. After discussions with Stan Shenton, and with Rudi when I returned to Switzerland, I agreed. This lead to a 21hr drive through blizzards across France on the Monday night/Tuesday morning to get back to the UK only to be back on the continent by Thursday for my first meeting with Kawa at, I think, Tubergen?
I have to say that I was very grateful for Rudi and Danes understanding in insisting on my taking up the offer, wonderful couple

Rudi used a DS21 which the outfit sat on the roof. I think it was '75 when he replaced it with the CatVan. Rudi designed and constructed it from another DS21. the bike went in the CatVan which also incorporated a fully fitted kitchen.

Rudi Kurth / Dane Rowe DS21 Cat "transporter".

If you want to see what he and Dane are up to now http://www.catbikes.ch

He is truly an amazing engineer

More on Rudi Kurth and the amazing range of projects he has been involved with.

http://www.classic-m.../rudi-kurth.htm

A page about Rudi Kurth's designs
including this nice photo:

The 1967 Honda powered CAT, Rudi Kurth raced it with Jean-Claude Gudel in the IOM TT.

Edited by philippe7, 22 May 2009 - 22:48.

[HEMEYLA]

Absolute astonishing detailed pictures from the Cat III there ..... Link

Edited by HEMEYLA, 23 May 2009 - 00:06.

[philippe7]

Never knew the Cat-3 was powered by a Honda triple

But apart from that, nice pics indeed, and good to see the outfit restored and still there !

[picblanc]

The pic with the Cat on the roof of the Citroen, reminds me of the DVD Cheval De Fer (again sorry!!) there is an aerial type shot of an empty/emptying paddock after a GP, & smack bang in the middle is the Citroen with Cat on top.

Edited by picblanc, 23 May 2009 - 10:47.

[fil2.8]

Came across this in an old copy of MCW , if it's of any interest

[Herr Wankel]

Came across this in an old copy of MCW , if it's of any interest

Thanks for putting that one up mate.I was beginning to think I'd dreamt it.
HW

[Coupe Kawasaki]

Thanks for putting that one up mate.I was beginning to think I'd dreamt it.
HW

That is one seriously modded CB450! It can't have been very quick can it?



David

[7okai]

I guess that thre may have been some concurrent construction happening in opposite ends of the world.

Dad started building a 3 cylinder Yamaha based on the TR2 engine and chassis in 1971. With offset, de~stroked crankpins, the capacity came in just under 500cc. It originally ran as a typical 120 degree 3 cylinder configuration with what was considered state of the art Krober 3 pole ignition. First raced at Bathurst, Easter 1972.

Clutch problems were the biggest issue, as the TR2 was still an oil bathed clutch. Heavier clutch springs, and eventually, hydraulic actuation failed to 100% cure the problem.

The release of the new TR3, with 64 x 54 bore and stroke, 6 speed gearbox, dry clutch and CDI ignition offered a much better platform for reliable development. So, the project was eventually shelved. There was potential there, but very difficult to produce a reliable machine.

There were many TR3/TZ350 variants over the years.

One interesting project that we ran for part of the 1984 season in Australia was a 3 cylinder 350. Interesting by means of following a different engineering solution to the easier "graft an extra cylinder onto the timing side" that was so common.

We reversed the cylinders on a TZ250G, having the carburettors at the front and straight exhaust pipes out the back, finishing through a modified TZ500J seat. The interesting part was the 3rd cylinder crankcase was incorporated into a casting that was based on the original clutch side cover. The primary drive gear for the 3rd cylinder mated above the original. The cylinder had the exhaust facing forward and the carburettor at the rear, in the normal fashion. With this configuration, the 2 pistons in the reversed cylinder now thrust against the cylinder wall below the exhaust port, rather than rocking into the overly large inlet port that this model had. The 3rd cylinder crankshaft was running in the reverse direction and the same benefit applied here.

The crankshaft was de~stroked to make it conform with the 350 class rules.

The performance was an improvement over a standard TZ350. The power was actually spread over quite a wide range and the potential for a seriously fast 350 was certainly there.

In retrospect, my development skills and feedback were quite limited. There were some carburation issues that we should have been able to overcome, and these days, I am sure that we would have had far superior acceleration than we were getting. Also, a modern ignition would have been a godsend.

I do recall the late, great Len Willing passing a comment to me about the bikes speed..."when that thing gets going, it is fast" That was some compliment to me, and will never be forgotten.

Anyway, hindsight is a wonderful thing. I sometimes wish we could turn the clock back and do it "right", but really I am happy with what we did.

So, my brother had a ride on it at a club day at Oran Park. He was reving the tits off it, and the 3rd cylinder crankcase split. I maintain that the primary drive gears needed a groove in them to help stop the oil "pumping" the gears apart.

So, we had the rest of the year off, saved up and used the same very special PRP aluminium chassis as a reversed cylinder TZ350 twin for the 1985 season.

All good fun.

Here is a pic of me riding a loosely based 3 cylinder replica of the original 3 cylinder. Loosely based means TR3 engine.

Edited by 7okai, 08 February 2010 - 11:00.

[pushstart]

Here's my pic of Ditchburn on the Ted Broad triple at Brands. Cant really add any more info on this as I don't remember anything of it or even how long Ditchburn rode it for. So just enjoy the Photo.

[fil2.8]

Great pic , PS , just coming down to South Bank ??

[pushstart]

Yes, it was one of my favourite spots for both watching and pic taking.

[picblanc]

Here's my pic of Ditchburn on the Ted Broad triple at Brands. Cant really add any more info on this as I don't remember anything of it or even how long Ditchburn rode it for. So just enjoy the Photo.

great photo!, he rode it till he went to Kawasaki, then Dave Potter took over in 1975 by then in a TZ700 chasis I think?

Photo Copyrighted to Graham Etheridge, racebikepics.

[Helvetica]

Absolute astonishing detailed pictures from the Cat III there ..... Link

Hi everyone, Dane here, Rudi's other half. The CAT at that 2008 Concours d'Elegance was in the possession of a very long-time friend in the USA, who had three CATs (CAT II, CAT III and the CAT Monark 3-cylinder solo) in his living room. He showed them at Concours all over the USA and southern Canada. We were incredibly sad to hear that he died of a heart attack in mid-January. The CATs will be coming back home to Switzerland.

[tonyed]

Nice to hear they are coming home 

Raced a 3 cylinder 500 Crescent myself in 1976/77 won a couple of championships on it.

Came across some 500 Crescent engines recently where the top of the cylinders have been machines of and new cylinder heads reattached with external threads on the cylinder jacket to establish a much tighter swish than the originals which was one draw back with that engine.

Why Yamaha never built a 500 3 themselves to market to club and national class racers the same that Suzuki never made the TR500 water cooled twin available I do not understand other than either ignorance of the probable market or conceit marketing only the much more expensive 500 fours I will never understand.    

[philippe7]

Hello Dane, very sorry to hear that your friend Donald passed away. I had many e-mail conversations with him about 10 years ago, exchanging pictures and informations of various Cat projects, and he was always very gracious and helpful. I seem to remember he was a member of this forum, but I just can't remember under which alias he posted ....

 

 

 

edit : I found it - he actually posted under his real name, Don Ludewig . May he RIP

 

https://forums.autos...30-don-ludewig/

 

https://forums.autos...rch_app_filters[forums][searchInKey]=&userMode=content

Edited by philippe7, 17 February 2022 - 17:24.

[Helvetica]

Me again. I just noticed an old posting about the Yamaha 3-cylinder 350cc which was ridden in Grands Prix by Katayama-san.

The story of that bike is this - Rudi built our 3-cylinder Yamaha engine after trying normal 2-cylinder engines - one borrowed from Philippe Coulon and another from the English  "milord", Piers Forester, a lovely and very humourous bloke, who died so tragically a couple of years later. Anyway, when we were up at the Assen TT, with our 3-cylinder Yamaha, we had a paddock visit from Tanaka-san, who was the Yamaha Race Manager at the time, based in Amstelveen. He was very interested in the 3-cylinder and how it was put together and asked if Rudi could make a 3-cylinder for them to try. First Rudi just built the engine for them, then they asked whether Rudi could make an entire bike for them, with a monocoque frame, like the Monark solo. Which he did.

But I have seen some later mag reports which don't mention Rudi at all - I won't mention who they say built the bike, but it wasn't him at all - he was only a rather braggy workshop manager and mechanic who had nothing at all with the construction of the bike, nor with the contact or relationship between ourselves and Yamaha. It rather pees me off to see someone else taking the credit for that beautiful machine.

Yamaha was so incredibly generous - I remember whether we asked Tanaka-san whether they could spare us just two 2-cylinder blocks for ourselves as spares, and a few days later this huge lorry from Hostettler (Swiss Yamaha importers) pulled up and I thought, crikey, our little box must be right at the front somewhere - no, the driver unloaded a fork-lift thingy and started wheeling crate after crate into our workshop - engines, carburettors, gearboxes, electronics...

 

And when we visited Tanaka-san at home a couple of months later, we got another gift - a little black cat called Kuro (Japanese: "black") who went with us to every race, travelling in the Catvan and wandering around the paddock to visit friends like Barry Sheene, Heinz Luthringshauser and Rolf Steinhausen. He (Kuro) always knew when racing was over and it was time to come back to the Catvan. Since then we have always had a black cat and they have always had Japanese names. Our current second moggy is a tabby, called Kenji, in honour of Tanaka-san's son, who was just a toddler at the time.

 

(Sorry for nattering on.... )