Topic: CR750 / Dick Mann replica - replica front forks from GL1000 forks ?

[voxonda]

This is a pic of one of the works bike from Daytona, 1970.  I don't know if this is the Mann bike or not.

The problem you are going to run into is that not all of the works Hondas were the same.  Most of the attention is focused on the Mann bike but there were 3 other bikes that can claim to be authentic Daytona CR750s and they are not identical.  I know you are trying to replicate the Mann bike but what is the benefit of having alumium and steel replicas of magnesium and titanium one off race parts.  Like the French bike, your forks may look close but underneath they are still GL1000 forks.  My advice would be to replicate the kit bike because the end product will be much closer to what it is supposed to be.
 
Scott

+1 that. Seen a lot of "Mann-replica's" in life but not one could stand in the shadow of the real deal. They all had their own flaws. No problem and some of them are beautiful bikes but do not call it 'an exact copy of the original'. There are only few people who actually saw the real thing, sadly I am not one of them, so all we have is these pictures. Just make your own CR or CB750R and enjoy it.
Yoshimura used to have the 4 bolt Ti lowers in their program according to catalogue I have.

Rob.

[Sam Green Racing]

As Rob says, build what you can and enjoy, I doubt anyone could build a Daytona replica since they have all vanished and I know for a fact that four of the origional team would have big problems remembering all the details of the bikes.
One of the origional mechanics is crewing for me at a meeting in September, he asked me to remind him nearer the time. If he can't remember whats coming up in a few months time, how's he expected to remember bikes that he worked on for just a few weeks forty years ago. (no disrespect Steve if you read this)
I started the Daytona thread some years back to try and entice three of the riders and a few mechanics from the UK to put some of the stories to bed, none have responded despite several request over the years. One of the stories was about the 68 bike. It has been writen that the bike was built by Texas dealer Woody Leonne as a back up bike for Dick, When Ralph Bryans crashed and burnt his bike, it was writen that the bike was rebuilt and raced by him. The fact is he rode Bill Smiths bike and Bill rode the Woody Leone bike.
This is just one story that has been confirmed to me by two of the team, can you remember fine details of things you did from forty years ago.

Sam.

[lordmoonpie]

+1 that. Seen a lot of "Mann-replica's" in life but not one could stand in the shadow of the real deal. They all had their own flaws. No problem and some of them are beautiful bikes but do not call it 'an exact copy of the original'. There are only few people who actually saw the real thing, sadly I am not one of them, so all we have is these pictures. Just make your own CR or CB750R and enjoy it.
Yoshimura used to have the 4 bolt Ti lowers in their program according to catalogue I have.

Rob.

+1 to what Rob says, just build your version and enjoy it. I've held a set of the four bolt Yoshi magnesium fork legs in the past but couldn't afford them - massive money even 2 years ago if you can find them.

On Doctor_D's comments about Ti fork legs, I guess the thing to bear in mind with the CR750s of the era is they were the best of the best at that time. now, things have moved on so much a lot of the original designs are proven to be flawed. I had a set of kit pistons a while back and sent them to the wonderful people at Arias to re-create a brand new set for me. They refused stating that the metallurgy and design was below their minimum standard and they actually commented that they believed teh design was dangerous in their opinion as it was not mechanically sound at the revs I wanted to put through it (My CR is a 750 cc bike not 823cc). Point is, you can go too far with the replica idea and make something more expensive and less "good" as a result...

[754]

Is the Mann bike, right side shift.. looks like it in the one pic?

[H2Eric]

The Mann bike looks like the discs are thinned, is that correct?

 Around 72 ish in a bike mag, I found an ad for Magnesium,  4 bolt clamp..lowerlegs with dual disc mounts for Honda sohc.

 But I think they were for CB500, and I think the name was Checkered Flag Racing. Also I think there was an article converting to dual disc,back around that time which used a kit that came with a lower leg with correct mounts..

 Mainly bringing this up because, it appears there was either 2 places made 4 bolt lower legs,in America.Either that or the place I mentioned, made the Mann legs..

Correct 754
I had a set of the 'Checked Flag Racing' fork legs for my CB500 in 1973/74. they were advertised in the Yoshimura catalog at the time (which I still have) and came as part of a kit for a dual disc conversion ($189.50). The bottom sliders were made of magnesium and you can imagine what the British salt laden winter roads did to them.

Cheers
Eric

[Sam Green Racing]

How's your bike coming along Eric, any pictures yet, Mikes itching to see who has the big block running first.

Sam.

[lordmoonpie]

Is the Mann bike, right side shift.. looks like it in the one pic?

Yep - right side shift with a linkage through the rear of the frame. The Japanese version of the race bike uses a single piece dogleg reverse lever off the gear shaft on the left....just like this...

[CR750]

Hi Guys,

@ kos thanks for the offer on the magazine ! (Pm sent)
@ naopleon; I guess we look at the same stuff, thanks for identifying ;-)
@ srook thank for your input and images !

@ everyone
Thank you all for your kind advise and wise words. I definitely can see what you're all trying to say ( and it seems you all kind of agree; that's nice   ), but at the same time also feel it needs some response/motivation.

My believe: everybody is entitled to, and should live/work by their own belief (within reason... before we go completely off-topic !).
It is my opinion I want to build an accurate replica, either of a cr750kit or the Dick Mann bike (both like seen in the previous mentioned 1970 cycle magazine).
Part of the fun for me is the hunt/search for info, the other part is coming up with (smart)plans to remake/resemble original parts and doing so.
I have no unlimited budget, so I need to make choices. If it will be a kit replica or a Dick Mann does not matter for now, either way I will not be buying all the original parts simply because I can't (afford it) anyway, so I will only buy parts which are essential/I can not replicate/are cheaper to buy then make.

My replica parts need to function and look like the original, but things on the inside or under a coat of paint (materials) are sacrificable for me if it will become too expensive ( + sometimes we also have better materials now ). I want to make a nice bike up to my standards (high) which will be very close to the original for the eye of the beholder, because that's why I build a replica. In my mind if I you start to plan building a "replica"' of something it does not make sense to me to make it look a 'bit' like the original. Especially when/if you could do it properly when studying the original, unless of course forced by budget or imagination. The argument "it will never be an original so why bother" will therefore never be part of vocabulary, because I am building a 'replica' to begin with. Because of this 'vision' I for one do not understand why some people go to great length to get, let's say (fictive example), the correct rear drum brake on their cr750 replica (> 2000 euro), and then put the wrong seat (150 euro) on their bike....because it's obviously not a budget choice. But it of course all matters how serious you take things and what idea you start with in the beginning. If I would want to build a cr750 inspired cafe racer, I would happily combine an aluminum CR look-a-like gas tank with some modern cbr900 front forks...

Let's get back on on topic:
For reasons mentioned above I am studying an evil plan to use Gl1000 donor forks.
I think most people will not be able to tell the difference between chromed titanium and chromed steel or painted magnesium or aluminum  .
So.... does anybody have any first hand experiences on welding front forks or seen examples ? Does anybody have a better plan ?... I can use all the info !

Sander

[bwaller]

There have been some here that have welded brackets or lugs to forklegs and claim not to have caused any distortion. I wanted to do the same thing a couple years ago and my weldor pal said "no way" that warping was inevitable. He's done this his whole life but maybe he is wrong.

I don't mean to add useless dribble without first hand knowledge,  but it appears that this is being done succesfully.

[754]

I would be a lot more comfortable doing any major welding on a fork leg.. if, I had the proper hand/finishing reamer of sufficient length, to run through the leg, when finished.

 I know they are expensive, but I do actually have them for some Standard sizes, that I lucked into. I also started making some fork legs(not for a 4), but cheated, and bored from both ends, then used screwon bottom..

[ttr400]

I agree 100% to cr750's last post.

I am also undertaking the building of a D Mann replica, and yes I am sure you other guys have also spent many hrs studying the original photos from the day. In fact it is starting to make my head hurt.  

Why not build a replica to as close as can be to the original in looks, In fact the replica will probably be a better engineered machine than the original. As for never recouping the cost if one was to sell these machines...I disagree, look at the exotic sports car market, the replicas are worth a great deal of money. ( a D type Jag comes to mind) My reason (as I'm sure with others) to build a replica is I could never own an original, I believe replica's of famous machines (bikes and cars) will keep the history alive in many years to come.

OK, to my plan for the 4 bolt forks. I have decided to use xl350 forks (35mm) which I am going to weld the correct mounts to the legs. My welding buddy has done welding on fork lowers many times. I asked him about the strength on Saturday when we were fitting up the exhaust (thanks Simon), His reply was that they do not warp as the quality of the aluminium is very good.
I will be machining up the mounts to the design of the DM CR, I'll make extra if anybody needs them. No lead time as yet as I have quite a few parts to make, including the caliper mounts.

Kevin

[CPHjimm]

Lordmember1 welded brackets on his forks and says they didnt warp. http://forums.sohc4.net/index.php?topic=70333.50 but I would use a reamer after the welding. A normal length reamer would work with an extention.

[lordmoonpie]

Lordmember1 welded brackets on his forks and says they didnt warp. http://forums.sohc4.net/index.php?topic=70333.50 but I would use a reamer after the welding. A normal length reamer would work with an extention.

So did I  - big old bracket welded on to accommodate my AP lockheed caliper. raced for 6 years afterwards with no issues - it can be done successfully...

[voxonda]

Instead of welding the bracket. You can think about welding the 4 bolt clamps to the oem lowers. Has been done before. But no matter what it is kind of cheating. 

[CR750]

Hi Guys,

that's all good input !

@ 754:
Yes, a pass with a reamer seems like a good idea anyway, even if it does not seem to warp.

@ttr400:
Are the xl350 forks properly dimensioned (not too long ?) Any reasons why you choose them over gl1000 or were you not aware of those at the time ?
Let's keep in touch on our experiences and builds !

@CPHjimm:
good lead; I've just read his thread and it seems a good result, will try to get in touch with him about it.

@ Moonpie:
That's encouraging, I think I will do a test run on some old bend ones i have laying around and if that turn out decent just go for it.

@ Voxonda:
Thats another option I considered, but when I looked at it it seems you would have to build everything up with welding/ or cut of the bottom and weld the gl bottom on it.
Then I started to think... and I thought i'd rather risk loosing my front brake(s), then my entire front wheel if you make me choose:

http://www.youtube.com/watch?v=V8COCPyB-go



Poor guy.... you see him think; is my welding holding up ?

[voxonda]

Hey cr,

I would not consider both! I always wondered about the 4 bolt clamps, think they contribute very little to the total rigidy imho, if used with the oem axle. The 2 bolt with 20 mm axle does a better job. Again imho.

Rob

[754]

 A few thoghts..

 If you do go clamp on mounts, turn the fork leg in a lathe, and true up where it sits...keeps everything square..small shallow keyway would not hurt if its thick enough.
 K3 and later 750 forks have greater wall thickness as they do not use a sliding bushing on the fork.
 I think that person was looking at XL 350 forks because they are 35mm, and fit stock trees.

 The lower caps are diecast, not machined, IIRC, but fork lower end is machined.. so I could see how it can squirm around and a 4 bolt cap may be of some benefit..

[Ricky_Racer]

CR750, FWIW Yoshimura did make a run of CB500/550 magnesium fork lowers that had a four-bolt bottom. Finding a set might be difficult, but I've attached a couple pics in case you run across something that looks like these. Good luck on your project; it will take time and effort.  It took Vic World almost ten years to build his CR750 but every part he used was original CR. I don't think Menani was making the CR750 replica rear brakes back then, though.  RR.

[ttr400]

CR750..Yes the XL forks are 35mm, I will shorten the tubes to get the correct length etc. Did not want to mess around trying to match the 36mm of the Daytona bikes, plus I think to the eye they will not look out of place.

Kevin

[Phil]

I have GL1000 forks fitted to my Dresda GL1000! They are fitted with AP Racing callipers and lapped the IOM at 102mph in 1975. They can't be too bad!

[Phil]

For interest - Sumiya's bike.

[kos]

That last pic is of Sumiya bike Daytona 1973. Those forks are the latest version from Honda kit parts, 4 bolts, yes, but not the Dick Mann type. part number 51400-300-971. Fork tubes with no changes in diameter as they go up to top triple clamps. How do I know this? My friend from Colorado has the spare 1973 bike in his basement.+
 Same forks as bike that was posted on CR750 thread months ago that was for sale at swap meet in UK.

KOS

[Ricky_Racer]

I have GL1000 forks fitted to my Dresda GL1000! They are fitted with AP Racing callipers and lapped the IOM at 102mph in 1975. They can't be too bad!

Phil, do you have any photos of the GL1000/AP front end you can post?  Thanks!  RR

[voxonda]

Hey Ted,

Here a pic of such combo, hope you do not mind Phil?


Cheers, Rob

[Phil]

Of course Rob! I will take some better pics but for now ...