Hi all, I hope you've enjoyed the Summer weather. (Here in the UK we apparently have a national emergency if the ambient exceeds 30C )
Anyway, the TT1 project has been very slow lately with a crazy amount of time spent trying to get a UK manufactured fairing to fit my not-so-sleek exhaust..
Attached are some photo's.
I did have a mild heart attack when the stepped drill went one step too far on a single hole of my oil cooler aeration exercise. You can have fun trying to spot which one!
But here are my questions for some upcoming work:

1) Have people found an approximate target front / rear weight distribution for track use? I have 18" wheels and currently, (with complete exhaust), oil but no fuel and minus rider, I have 64.2kg Front and 65.3kg Rear. (49.6% F and 50.4% R) I think my bike does look a little high at the front and could probably do with dropping down through the forks and / or raising the rear a bit anyway. I understand that this should all be done with fuel and rider in all the gear etc. but if there are some target ratios that would be helpful.

2) I'm pretty sure my 41.7mm M1R forks are from a 750 Paso, as they have the right slider fitments for P08 calipers. The original springs are very stiff so I replaced them with some Hyperpro (Dutch) ones, which are supposed to be progressive from 6.5 - 12.3 N/mm. These required a fair bit of preload just to fit, and have ended up feeling not much different to the originals TBH.
Does anyone have experience of re-springing these forks for a track TT1/2? Looking on-line it seems like something around 8.5 N/mm might be a reasonable starting point (e.g used on some SV650 race bikes etc.) , but from my experience with the Hyperpro ones I'm thinking something less stiff might be better?
I can go back and weigh the wheel, subtract from the overall front weight, estimate sag required etc. but again, if there's knowledge already out there, this would help as a starting(?) point.
I also know you can pay for complete replacement internals from various suppliers but I was keen to try to get the original ones to work if I can.

3) Also, I'm now looking at mounting the front blade type mudguard / fender. Looking at the YouTube video of the Tony Rutter bikes, it seems they were mounted using spring loaded bolts into the fork sliders. Do you think this was to allow adjustment for different front wheel sizes? Or maybe just a way of not stressing the fibreglass too much? Just a point of interest really.

Thanks as ever for sharing all the knowledge here.
I'll keep you informed of further progress. (I still haven't stripped the engine to confirm the cause of the oil foaming issue...)

All the best
Rob S

You may have overwhelmed us with detailed questions.

I believe that the 750 Paso forks are the longest of the many (how many) variants of M1Rs. So, often, there is a lot of stanchion showing above the top triple clamp when put on these frames. I use between 20 and 20.5 inches measured from center of the axle to top of the lower clamp for these forks, with the bike just sitting upright all by itself. Just depends on how twitchy, or not, you want it to feel.

You can also experiment with the fork oil weight if they feel too stiff. Only the left leg controls compression. I just put some 7wt in a set that will be on the street.

I am not an expert with these now-oft-maligned (compared to modern) vintage forks. Cranky probably is. Have you seen the old two or three-page article about working with these? If not i have it on a computer somewhere and can find it - see PS: It may help a bit.

Recently the issue of proper swingarm angle came up, and the range was between 12 to 15 degrees. So you have wide latitude there, depending on how much you want to “tip” the bike. In the old days that was’t a lot.

I have never seen a fender mounted on springs. Odd thing to me, and a detail somehow missed. That photo does not really look like it is from a vintage TR TT bike to me. Just off on a few things. But then i wasn’t there.

Your work looks really good Rob. Yes, i can barely see the bigger hole.

MikeV

PS: See marzocchi M1r thread starting April 7, 2018 in F1 Technical section.

I can't see any reason for a spring mounted fender, might actually be dangerous. What I do see is a convenient way to hold the fender in position and adjusting it for height before making the solid spacers.
Flattop.

Thanks Mike and Flattop for the replies and info.
I'll read all the previous thread, take some measurements and adjust the forks accordingly.
FYI here is the video of the original Rutter machines with the strange fender mounting:
https://www.youtube.com/watch?v=YL-TkaTbHa0

Hey Desmorob... I watched the video. It looks like stacked cones. Add or subtract a few and change the height of the fender for different wheels or tires. Pat Slinn would probably know.
Flattop.

My suspicion is that this is the one and only time these bikes had those particular parts.

It is not unusual to see a fender jacked up off M1R forks, often with round spacers of some kind. I have used aluminum tubes, or nylon spacers. You just have to do what is necessary to get some good tire clearance. And rim/tire combinations from 16 to 18 inches make them all unique! So you are free to design your own.

MikeV

Hi Desmorob, does your lower triple clamp hit the frame tubes? Most of these TT frames use a spacer at the lower stem above the lower triple clamp so it doesn't strike the frame much. Anywhere from 5-10mm aluminum. Zoom in on the lower. This might help with your lock to lock range. Agree with the guys on the sprung fender. Lou

Hi Folks, thanks again for the feedback.
Yes, I can see you're right - they are stacked shims rather than a spring mount on the forks. Apologies for not seeing that myself! But at least it's a great YouTube video to watch

Hi Lou, no the lower clamp doesn't hit the frame tubes (just!) but I may have to limit the steering lock (or modify the fairing) as my fork centres are (I think) a bit wider than Pantah ones, at 19.5 cm, and the tubes clash with the fairing quite quickly. Currently the steering lock is only limited by the steering damper, so I need to revise the arrangement.
I probably need something like the Italian Iron bolt-on...

Once I've got all the fibreglass parts ready for painting, next will be to fabricate the exhaust silencer. So I'll be learning how to TIG weld soon!
I'll let you know how it goes.

(Then I can remove the engine and investigate the oil foaming )

Keep well all.
All the best
Rob

Yep, Lou spotted the triple-clamp problem. You might want some of those ribbed rubber tank bumpers placed on your frame rails behind the fork tubes, before you smack that nice paint. And maybe under the tank. Or even some radiator hose as a temporary fix. MikeV

MIG works too. Good luck.

I went back and measured the three bikes i have with 18-inch wheels, all Pantah frames, and they are +/- 21.5 inches from axle center to top of lower triple clamp - or just a tad below the steering stem. That is without the spacer Lou mentioned. The figures i gave before were from bikes with 16 or 17 wheels, TT or F1 frames, with steeper rakes. MikeV