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Post by icarus001 on Jul 9, 2013 20:17:41 GMT 1
How do you go about working out the correct geometry to set if you change the front end?
I.e. - I plan to fit a TZR250 front end and 17" wheels, initially I bought a TZR250 top yoke with bar mounts welded on, but this won't work because the TZR250 forks are much longer than standard LC forks, so the front will be about 6" higher unless I can slide the forks up quite a bit, but that wouldn't be possible with normal bars on because they'll clash, so I'll have to use clip-ons. No problem there, I suppose. Thats the easy bit.
I've got an NK modified standard swingarm that will take a 3.5" rear 17" wheel, but that will lower the rear, so how do I then match the rear height? Is it as simple as it sounds and just have a jack-up kit made?
How do I know what size to have the jack up kit made to?
My LC handles brilliantly, I don't want that to change, but I do want less unsprung weight and forks that don't flex like matchsticks, hence the wheels and forks.
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matt7
Thrash Merchant
Smell of the 2 stroke & the roar of the crowd
Posts: 445
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Post by matt7 on Jul 9, 2013 20:22:53 GMT 1
Have a look on YPM forum, one of the lads was running LC with TZR 2ma bits - he does come on here I think 'Higgsy' ? www.ypmrc.co.uk/forum/
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Post by icarus001 on Jul 9, 2013 20:29:16 GMT 1
Have a look on YPM forum, one of the lads was running LC with TZR 2ma bits - he does come on here I think 'Higgsy' ? www.ypmrc.co.uk/forum/Thanks, I joined there this morning, just waiting for the email saying my account is open. I might be having a crack at YPM at some point.
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Post by rich on Jul 9, 2013 20:34:59 GMT 1
Hi, a 3.5 x 17 rear wheel will run a 140/70-17 tyre so won't be very far off the standard 18 incher with skinny tyre so the ride height will be pretty close to standard. I run the same size rear in my hybrid with a Metmachex arm and haven't jacked it up although I do run the eccentrics so the spindle is at the bottom. And yes, 2MA forks are longer so do have to be slid through the yokes. If I were you, I would take some height measurements from the standard bike and get it as close as you can. It's a common conversion so I can't see you having too many problems and there's always plenty of advice available
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Post by icarus001 on Jul 9, 2013 20:55:29 GMT 1
Hi, a 3.5 x 17 rear wheel will run a 140/70-17 tyre so won't be very far off the standard 18 incher with skinny tyre so the ride height will be pretty close to standard. Yeah I suppose you're right, the 17" wheel is obviously an inch smaller but the 140/70 tyre should be taller. (Aspect ratio means 80% of 110 is less than 70% of 140) Doesn't look taller though
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goodpw
Weekend rider
Posts: 87
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Post by goodpw on Jul 9, 2013 21:42:15 GMT 1
I think you could probably preload the damper rod. I've done this before with other bikes, the fork just thinks it's shorter but spring rate might take some setting up. Take the fork apart releasing the damper rod from the bottom of the slider & leg, the bolt can be a little fecker & is soft as babyshite. When it comes out of the slider you should see a spring that rests on the under side of the damper rod 'crown'& acts on the inside bottom lip of the slider, this is for a bit of damping at full fork extension. Make a spacer of the same inner & outer diameter as the short spring & to the length of drop you're after. You'll probably need to shorten the main spring(long one... not the short damper spring)as well but I'd cut it 1/2" less than the spacer. 1" spacer = 1/2" of spring length removed, at least you may benefit from a bit of spring preload & then you can remove more if required.
PLEASE NOTE...I have not done this on an LC so have no idea about what dia/length spacer or spring length will be needed. Just saying that I've done it on other bikes to get round the problem you have. Hope it helps. Goody
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Post by icarus001 on Jul 10, 2013 18:57:01 GMT 1
This is going to turn out expensive, the forks I bought are like bananas, so I've just shelled out over £100 on some more, plus clip-ons. Plus new yokes.
I should have just bought a bloody RGV, lol.
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Post by jon on Jul 10, 2013 19:22:28 GMT 1
You mention the TZR forks are longer than an LC, so I assume you are wanting to fit them to an LC? You also mention you have a standard swinging arm modified by Nigel. Is it an LC swingarm modified for rear disk, or a TZR swingarm to fit in an LC? I have put TZR front and rear in my LC and am more than happy to tell you how I did it, and what worked and what did not. I believe Norbo's ride this year (the furry LC) also has this done. If you want any advise or photos about how I did it just ask. P.S. if your like me (6'4") RGV's are nice to look at, but impractical to ride
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Post by icarus001 on Jul 10, 2013 20:13:53 GMT 1
Hi Jon, yes I intend to put it into an LC. Its an LC standard swingarm modified by NK, although the only 'modification' is a lug welded on to accommodate a torque arm. I've had to pack the wheel off so the sprocket doesn't foul the swingarm.
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Post by icarus001 on Jul 10, 2013 20:34:51 GMT 1
And here is what I mean about the yokes, you can't slide the forks up because they'll foul the bars, so the front end would be too high unless I chopped the forks down and thats a job I just don't want to do. I've bought new clip-ons that arrived earlier and new forks are on their way, as I said the ones in the job lot were so bent I expect they'll start talking like Larry Grayson soon.
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goodpw
Weekend rider
Posts: 87
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Post by goodpw on Jul 10, 2013 22:01:52 GMT 1
I think you could probably preload the damper rod. I've done this before with other bikes, the fork just thinks it's shorter but spring rate might take some setting up. Take the fork apart releasing the damper rod from the bottom of the slider & leg, the bolt can be a little fecker & is soft as babyshite. When it comes out of the slider you should see a spring that rests on the under side of the damper rod 'crown'& acts on the inside bottom lip of the slider, this is for a bit of damping at full fork extension. Make a spacer of the same inner & outer diameter as the short spring & to the length of drop you're after. You'll probably need to shorten the main spring(long one... not the short damper spring)as well but I'd cut it 1/2" less than the spacer. 1" spacer = 1/2" of spring length removed, at least you may benefit from a bit of spring preload & then you can remove more if required. PLEASE NOTE...I have not done this on an LC so have no idea about what dia/length spacer or spring length will be needed. Just saying that I've done it on other bikes to get round the problem you have. Hope it helps. Goody Solution as mentioned before. Goody.
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Post by jon on Jul 11, 2013 18:58:36 GMT 1
You original thread has a photo of the calliper bracket which you now seem to have removed. I would guess this was not done by Nigel. from memory there were two things wrong with it. 1) the metal removed was from the inside face (thus moving the calliper itself nearer the disc and un-centralising it. 2)There is no mount for the torque arm? As far as the fork height is concerned, Goody is saying you should cut the fork internals about and thus lower the tube into the stanchion. This is the best route aesthetically, and will probably not effect the fork behaviour (but that is unknown). As you say you have a bent set I would definitely practice on them with this method. As I have adjustable ride height at the back, I went a different route and bought some clamp on risers so I could fine tune the ride height front and back to suit me once I had it on the road. I think mine is probably about 1" raised front and rear (it could be more?). The only problem is I had to make a centre stand from scratch to raise the back wheel when on it. I could talk you through in detail what your going to have to do with the back end, but basically: 1) Ensure wheel(tyre) centre is in line with swingarm pivot centre after installing rear wheel spacers. 2) You are eventually going to have to have top hat spacers made (once you have size) to go inside either grease seal. 3) Set calliper bracket to correct distance from disc. Weld (or affix) a torque arm bracket. 4) Check front and rear sprocket alignment. Your rear carrier looks un-machined. Expect around 9mm difference with this setup (every bike is different). This means you need to measure offset (twice at least) machine the carrier and get an offset front sprocket. If you go for an offset front sprocket to desired offset for this setup in an LC expect to start sawing the frame in half with the chain. P.S. From memory a 130/70 on a 17" is only about 1.5% smaller rolling circumference than standard LC (so it is negligible). P.P.S. I see you have primered the wheel and tyre. I hope you are brave enough to go for a different colour scheme on the tyre, everybody seems to be boring and pick satin black for some reason.
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Post by icarus001 on Jul 11, 2013 20:14:50 GMT 1
You original thread has a photo of the calliper bracket which you now seem to have removed. I would guess this was not done by Nigel. Yep done by NK. I did phone him and ask why he'd done certain things but to be fair to him it was done in 2007 and he can't remember, and said he'd probably just done what the customer asked for. I have top hat spacers, thats all sorted, NK machined the cush drive/sprocket carrier and swapped the bearings to take a standard LC spindle, plus supplied spacers, I have the receipt from NK for the best part of £300 worth of machine work. I've measured the rear sprocket alignment when I mocked it up as per the pictures above and I can position the rear sprocket exactly the same distance in from the side as the standard one, so alignment *should* be ok. So, one would hope that all that work was done to ensure alignment. The forks in the job lot are bolloxed, so I've bought new ones, along with a new top yoke and clip-ons. I'll put the clip-ons on upside down, so they won't be far off the position of renthal bars. The calipers have gone off for media stripping, full refurb and recoating, so they will be like new. My only concern is lining up the calipers and disks (but the rear should be ok, as I said the work NK did appears to cover sprocket and caliper alignment) and then geometry/setting up. I'll convert to 520 while I'm at it, I've got all the sprockets and chain I need.
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Post by icarus001 on Jul 11, 2013 20:19:50 GMT 1
Oh, and as for the wheels being sprayed...they were in shit state, over the winter I'll send them away for a proper finish, but for now I've done it with a rattle can just to make them look passable from 10ft away.
I also need new tyres, someone has put a 120 section tyre on a 3.5" wheel, its almost flattened out.
To be honest if I knew what I know now I wouldn't have bought the bits, half of them are knackered, but I'm commited now, so I'll finish it. Worse case is I'll put the LC back to standard, sell the good bits and use the wider wheels on a TZR250 I'm building.
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Post by jon on Jul 11, 2013 21:36:39 GMT 1
You'll feel much more of an achievement fitting those wheels (properly) into an LC rather than simply bolt them into a TZR you have. Really it's not that difficult. Ask questions or PM me if you want further advice.
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Post by icarus001 on Jul 11, 2013 21:49:45 GMT 1
You'll feel much more of an achievement fitting those wheels (properly) into an LC rather than simply bolt them into a TZR you have. Really it's not that difficult. Ask questions or PM me if you want further advice. Cheers. You're right, I'd like it to work, the idea was born out of wanting to reduce unsprung weight, I couldn't believe how much the standard wheels weigh. The TZR125RR wheels feel loads lighter, it will be interesting to see the overall weight loss, but up to 10kg wouldn't surprise me. The standard rear LC wheel with drum brake feels incredibly heavy. And the front with twin disks and heavy caliper is a fair bit heavier than the 125 wheel with single disk and much lighter 250 2ma caliper. As you say the mechanics of it aren't too difficult and I have a machine shop at work I can use, fully loaded with milling machine and lathes. But sometimes whilst these things sound good on paper they don't translate well into reality - I really like how the LC handles and moves, if this set-up doesn't improve it significantly then I'll just put it back to standard and move onto the next project, no complaints, there are worse things to own than a standard LC. Thanks for the help, I'll ask away if anything crops up.
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paulh
L plate rider.
Posts: 38
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Post by paulh on Jul 12, 2013 8:47:23 GMT 1
Hi, a 3.5 x 17 rear wheel will run a 140/70-17 tyre so won't be very far off the standard 18 incher with skinny tyre so the ride height will be pretty close to standard. Yeah I suppose you're right, the 17" wheel is obviously an inch smaller but the 140/70 tyre should be taller. (Aspect ratio means 80% of 110 is less than 70% of 140) Doesn't look taller though 18" on left with Avon, 17" on right with Dunlop - 17" is still lower overall
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Post by jon on Jul 16, 2013 21:39:11 GMT 1
Paulh, your picture of the two tyres does show an overall diameter difference, but the two tyres look a similar width also.
The 17" is Definately not a 140 section, as a 3.5" rim will take. This will make it near a dam it the same diameter.
The TZR wheel (and indeed swingarm) is very much lighter than that of an LC.
My advice is try it (I doubt you'll go back if your not concerned about having a standard LC?).
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Post by icarus001 on Jul 16, 2013 23:25:12 GMT 1
Paulh, your picture of the two tyres does show an overall diameter difference, but the two tyres look a similar width also. The 17" is Definately not a 140 section, as a 3.5" rim will take. This will make it near a dam it the same diameter. The TZR wheel (and indeed swingarm) is very much lighter than that of an LC. My advice is try it (I doubt you'll go back if your not concerned about having a standard LC?). The TZR swingarm is lighter? How easy/hard is it to fit? I'm planning on running the standard swingarm, simply because its easier, the TZR125RR wheel I have has been machined to fit. But I would put a TZR swingarm in if its not too much hassle.
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paulh
L plate rider.
Posts: 38
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Post by paulh on Jul 17, 2013 13:43:38 GMT 1
Paulh, your picture of the two tyres does show an overall diameter difference, but the two tyres look a similar width also. Its a 130 Avon v a 150 Dunlop - the 3.5 inch rim pinches it it a bit. Probably should have said the pic is track rather than road tyres, which probably confuses the issue.
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Post by jon on Jul 17, 2013 20:22:51 GMT 1
paulh, you need all 3 tyre dimensions to know its physical size. Inner diameter for rim size in inches, width and aspect ratio which you do not mention. The width is in millimetres, and the aspect ratio is the height as a percentage of the with (e.g. 140/70 is 70% of 140mm high).
Icarus, yes the TZR swingarm is a hell of a lot lighter. It needs a hoop welded on to fit an LC. I got mine done by NK racing with a height adjuster included.
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Post by icarus001 on Jul 17, 2013 21:56:56 GMT 1
Icarus, yes the TZR swingarm is a hell of a lot lighter. It needs a hoop welded on to fit an LC. I got mine done by NK racing with a height adjuster included. Really? Wow, I thought the standard one was quite light as it was. I might have a look for one now then. I expect NK has done loads of them and knows the machining and welding needed without me having do any homework. If I see one for a reasonable price on ebay I'll grab it.
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