Nc30 yokes to accept 675 forks

Post by **28hodge** » Wed Jul 16, 2014 6:31 pm

Before you read any further, the below information is from what I have read and understood on this forum and understood when I have spoken to people running the 675 front ends, I am happy to be told I am wrong on the details below.

Paul/mods if you are not happy with this post please delete it. Thanks

Hi looking for interest and opinion.

I am wanting to put some triumph 675 forks into my NC30 race bike, this is pretty easy to do in truth. The 675 forks share the same upper and lower yoke diameters as the NC35 forks. So to fit triumph Daytona 675 forks all you need is some NC35 triple clamps, then the RO adapter fitting kit. And you are good to go, you can use the nc30 wheel with the Triumph 675 spindle with no mods other than some additional spacers being turned up and a bit of fabrication to allow you to fit the front mudguard.

The use of the 675 forks allows a set of forks that actually have real adjustability and tuneability options being that they are a modern up to date cartridge fork. It also allows for the use of radial brakes again using the nc30 discs, there is a slight pad overhang as the disc are 296 whereas really the calipers should be used with 300mm discs, so periodically you many need to remove your pads and remove the excess pad that is not contacting the disc.

However, looking around NC35 triple clamps are expensive and rare, for what is a 20 year old item that may or may not be tweaked from crashes and 20 years of usage. They also require the addition of a RO fitting kit at additional expense.

What I’d like to do is have a set of NC30 yokes copied in all aspects with regards to rake trail and offset but with the ability to accept 52mm/50mm fork legs into the bottom and top yokes. They will have a NC30 stem in them to allow for them to be essentially a bolt on upgrade. The bonus of this is that if you do not want the expense of the 675 forks you could simply bolt in a set of RVF NC35 forks and away you go. I also believe that Triumph street triple forks are the same but are not equipped with radial caliper mounts and so are less desireable and hence cheaper. But please check that the forks used on the triumph street triple are 52mm lower mount and 50mm upper mount.

I understand (And agree) that NC30’s look better and correct with the RWU forks and a late set of NC30 cartridge forks with RO kit in them are a very good set up and adequate for the bike and its usage. I am purely after the additional performance gain that can be achieved on track from the use of modern bang up to date cartridge forks and radial brakes.

I have been in contact with a motorcycle engineer about this and it is something they specialise in, they are active members on another forum and anyone who is on PBmagforum will know them and agree that they are more than capable of doing this safely and correctly which to me is worth paying for, do you really want to be on your bike when the stem or triple clamps snap?!!?.

So is anybody interested in a set, they will look very similar to standard NC30 yokes but obviously made out of billet aluminium, I am not going to start requesting differences to each set of yokes what I have explained above is how they will come, there are no options on colours etc or offsets or concentric adjusters as this defeats the object, as the design time cad modelling and programming is the same if I get 1 set made or 10. So if I can spread that design cost through more sets it reduces the price if they are having to adjust and redesign for different requirements that cost saving is diminished. At the moment I have requested an price estimate based on 1 set and 5 sets.

I will not be making anything on these I will be passing them on at cost as I am really just trying to get some yokes for myself but spreading the design cost over as many units as I can.

I know there has been some issues to do with group buys so am happy to discuss postage of things and I am happy for you to contact the fabricator and have them send it direct to you if you wished

Post by **DocV400** » Wed Jul 16, 2014 7:08 pm

Seems an expensive way to do it to me, will the 675 Yoke stem not fit the NC Head-tube?
I machined up a simple extension piece for mine, to fit ZXR400L Yokes, I'd be surprised if the same couldn't be done for the 675 Yoke/stem . . .

Post by **28hodge** » Wed Jul 16, 2014 7:28 pm

Yes there probably is other ways around this, but nc30 yokes will not fit 675 forks so I am always going to need yokes, nc35 yokes go for, or people ask for ,daft amounts of cash, also as I purely ride on track billet yokes are stronger so less prone to bending and lighter which is always a good thing

Other thing is I what them to be as straight forward a bolt on upgrade as possible, simply fitting the 675 yokes will encounter ignition location problems, granted not an issue for me on my race bike. I've but will/may be for a road bike and also lock stops etc will need modifying potentially.

Post by **VFRkieran** » Thu Jul 17, 2014 12:56 am

What sort of money we looking at for one set mate?

Post by **28hodge** » Thu Jul 17, 2014 8:28 am

The machinist is coming back to me with an idea of a cost for a one off set and then a run of 5 sets. As soon as I get an idea I will update the thread so people can decide.

I have asked for them to have a new stem made rather than pressing out the old stem from NC30 yokes and then re pressing it into the new 52mm bottom yoke. Doing that would keep the cost down a little as its less items to machine, but it seemed a bit backward to me, pressing a 20 odd year old stem into new billet yokes just to save a few £ to me didn't make sense.

In addition I have asked for the ignition barrell holder to be made so that it is possible for it to be removed by unbolting it rather than having to cut it off if you don't want it, as 90% of track users would not want it whereas all the road users would, this will be bolted on underneath the top yoke so would not be visible and will not detract from the look of the yokes.

Below is the email I recieved from the machinist.

Hi Kurt,

We can definitely do that for you. I'm actually doing some street triple/daytona yokes at the moment for a street fighter race bike.

We can press out the stem or make a new one.

There will be a cost for design, setup time, & programming, so if you order more it would be cheaper as its spread over the quantity.

Sounds like a nice project, so let me work out some costs and get back to you. 1off and 5 off?

I would need a complete set of yokes with all the fasteners.

Hopefully if we can get a couple sets sorted it'll drag the cost down, but I dont expect them to be cheap, it may be possible for them to tweak the design to make standard NC30 yokes and then a couple sets of 675 fitment yokes and that may attract some more people.

But lets see what they come back with in terms of cost first.

Updates as and when I get them.

Goulime · Post by **Goulime** » Thu Jul 17, 2014 12:17 pm

Hi all,
Just to add my contribution to this post.
Jap4 already do this, i've ordered one few month ago, N30 billet yokes for NC35 fork and put 675 daytona fork in.
it's just plug n play.
As you've said you need 675 wheel spindle, custom made spacers. (i've used Nc30 billet spacers, larger one, i don(t remember if it's left or right one... and machined it ), and no problem with an 675 mudguard

Post by **28hodge** » Thu Jul 17, 2014 1:02 pm

Yeah I spoke to Gav at Jap4 a few months ago prior to going to Silverstone and he wasn't aware that the triumph forks slotted straight into 35 yokes, so I guess he looked into it and got some 35 yokes made up with 30 stems to allow this.

How much were they Goulime? I cant seem to find them on the website!

Goulime · Post by **Goulime** » Thu Jul 17, 2014 1:13 pm

Expensive ! 350£......
but so easy to fit.

Post by **28hodge** » Fri Jul 18, 2014 11:18 pm

Been chatting to a lad that has 675 forks on his nc30, and from his info and measurements this isn't going to work with a 30 stem.

Reason being the 675 legs are longer so to get the geometry correct you need to run the forks pushed through the yokes quite a bit, however the legs taper so once you have them through the legs and positioned into the top yoke to maintain the 30 geometry there is no ability to fit the 50mm clip on below the top yoke as the legs have begun to taper out from 50mm to 65m dia.

So it's either use a spacer sat below the top yoke or have the top yoke machined to incorporate this spacer as a machined part of the yoke.

But let's see what the machinist comes back with price wise!

Anybody know the difference in length of the 35 and 30 stems?

Post by **28hodge** » Fri Jul 18, 2014 11:21 pm

Goulime, I bet they are worth the expense though!