4L0 350LC rear suspension jack-up kit - anyone used it?

[dusty350]

Yes, I think longer will cause an issue. Not a problem on my twinshock bike obviously, but the clearance on the Lc passing through the muddie doesn't allow for much "tilt" on the shock, unless you modded the guard, but it's also chain run issues with top of the swingarm and exhausts.

[mangocrazy]

The YSS shock extensions have finally landed and I've been fitting them to the shock and trying out a couple of configurations. Here are the items in question, reclining on a wall:







The extensions as ordered and supplied are the ones with the longer nose, I just shortened one of them for testing purposes. I intended the longer nose ones to be used with the same type of slim locking nut that YSS use for the ride height adjustment, so if anyone wants to go down this route they'd need to buy one of the slim nuts. For my first test I used the extension as supplied with a second slim YSS nut (supplied by Firefox Racing). This is how it looked in position:







With the 'long' extension fitted I put the bike on its centrestand and realised immediately that it was never going to support the bike (at least, on level ground). It veered a long way left and right before coming to rest and was very unstable and not to be trusted at all. So I decided to shorten the nose of the piece by about 6mm so that the extension piece screwed fully home and flush with the shock body and dispense with the locking nut. This is what it looked like in this configuration:







The bike was still unstable on the centre stand, but not as bad as before, so I decided to use a piece of 18mm plywood I had to place under the centre stand and see if that stabilised the plot. I'm pleased to say it did - there was a few mm of clear air between rear tyre and ground using the 18mm ply, so that gives me the ability to adjust the chain more easily than on the side stand. Here's a pic of the bike outside on the plywood and on the centre stand (without tank and seat). It also gives an idea of how much extra the rear of the bike is jacked up over standard; there's quite a bit more fresh air between wheel and mudguard now...

It may not look like it, but the rear wheel turns freely and there is probably about 5mm between tyre and floor. As expected. when the bike is put on its sidestand it leans over appreciably more than previously, but this did not come as a surprise to me. I regard it as within acceptable limits, but it might be an idea to carry a sidestand puck around with you. At least it's not going to get blown off the stand by a gust of wind...  Here's a front-on pic to give you some idea of the angle of dangle:

As far as I can tell there is no fouling between the shock body and the mudguard/shock tunnel although I haven't ridden it anywhere, it's just been pushed in and out of the shed. I'll have to reserve judgement on that until I can test it, but for now I'm optimistic. I will be sticking with the short nose version of the extension as it gives me all the rear end lift I require. I will also be dropping the forks through the yokes (initially by 10mm) in an attempt to make the centre stand usable without carrying a plank of wood with me wherever I go...

[lcmarky]

Interesting read & I'd be cautious on dropping the front that much as it'll handle completely differently. Looks super precarious on the side stand. I made a new side stand for my hybrid given the change in ride height, but I've no centre stand given my pipes..

Once you're settled on the final ride height, how about tacking on some material to the stand feet to compensate?

[mangocrazy]

Mar 1, 2024 13:11:55 GMT 1 lcmarky said:

Interesting read & I'd be cautious on dropping the front that much as it'll handle completely differently. Looks super precarious on the side stand. I made a new side stand for my hybrid given the change in ride height, but I've no centre stand given my pipes..

Once you're settled on the final ride height, how about tacking on some material to the stand feet to compensate?

Yes, it's all going to be a case of suck it and see. I'm venturing a bit into the unknown on this, but experience with quite a few other old bikes leads me to believe that most of them respond well to being set up a bit more 'on the nose'.

And yes, once I've settled on the final ride height I'll either get a new side stand made up (or modify one to suit) and look at adding some material to the centre stand feet.

[diggerboy777]

Jan 25, 2024 5:39:47 GMT 1 masonmart said:

My overall thoughts on this are as follows. I have a good degree in Engineering and that included a lot of statics, dynamics and control engineering. No expert in bike design but I have some idea. If somebody asked me will jacking the rear suspension improve handling I would say no (or perhaps say, please define "handling?"), it will have the effect of making the bike turn faster but at the expense of stability in a straight line or longer corners. It will also increase the risk of tank slappers on bumpy corners. It can only ever be used as one component of setting and even then only under specific circumstances. By far the most important component is to have the suspension set up for a person of your weight. Is the standard suspension OK? Yes, it is fantastic for a wide range of conditions and as long as it is set up for you, I seriously doubt that any non-specialist could improve on it for a broad range of riding. The best money I ever spent was a Maxton drive in, new rear suspension, upgraded front springs and damping and all set up for me. The improvement was staggering.

Totally hit the nail on the head there, in my opinion,,, use a professional, bike set up for you, your wieght, your riding style.

[Tobyjugs]

I agree with Marky. Maybe two mm at a time and go for a good blast between adjustment.
As previously mentioned the back of Kees's bike was jacked up (because of clearance issues) and in the end the front end was also lifted slightly because he found the back end was losing grip in the bends after being jacked up.

I would also suggest when you have.found an adjustment you are happy with put a stripe over the extension piece locknut and shock so you can check if it comes loose.

[mangocrazy]

Mar 2, 2024 7:09:21 GMT 1 Tobyjugs said:

I agree with Marky. Maybe two mm at a time and go for a good blast between adjustment.
As previously mentioned the back of Kees's bike was jacked up (because of clearance issues) and in the end the front end was also lifted slightly because he found the back end was losing grip in the bends after being jacked up.

I would also suggest when you have.found an adjustment you are happy with put a stripe over the extension piece locknut and shock so you can check if it comes loose.

I think that, to avoid confusing myself unduly, I'll start with the back end. As it stands I'll set the spacer fully in (i.e. on minimum ride height) to see how it feels/handles initially. This equates to the third photo in my post above. That will increase shock length by 30mm over standard (340mm eye centre to centre as opposed to 310mm standard). If that feels excessive then I will probably forget the whole thing, and put it back to standard, but I'm hopeful that it will be an improvement. 

The stripe is a good idea, but the way the whole thing is bolted together means that it's very difficult (if not impossible) for anything to work itself loose, as everything is captive. A spot of Loctite on the thin black nut might also be a good idea once I've got it set up optimally.

As for getting the suspension set up professionally, there isn't a great deal you can do with standard non-adjustable LC forks that I haven't already done. I've had the forks fitted with YSS emulators and fork springs, and that work was done by a suspension specialist. I've also fitted the aforementioned YSS shock, which (as everyone who has fitted one knows) is a major improvement over OE and probably the best bang for buck mod you can do to the bike. What I'm doing here is less about suspension and more about tuning the handling and the bike's weight distribution and front/rear balance.

[mangocrazy]

Just a quickie to say that I have 5 extensions surplus to requirements and they are listed in the 'For Sale' section.

First come, first served.

Graham

[mangocrazy]

All extensions now sold. Thanks to all.

Graham

[mangocrazy]

Today dawned bright and sunny (as forecast) and so the LC was wheeled out blinking into the sunlight, had its tyres pumped up and we then went for an enjoyable little jaunt around some south Yorkshire/north Derbyshire scenery. This was the bike's (and my) first outing this year and it was the first time I'd ridden it with the lengthened shock and slightly softer shock spring (75 Nm as opposed to stock 80 Nm). I was also wearing new boots and helmet so was taking it steady until I had a few miles under the wheels.

But within a hundred yards or so it was obvious that the shock felt much better - more compliant and no sharp kicks up the spine over harsh bumps. To be honest the handling and steering didn't seem that much different with the longer shock, just a more composed and balanced feeling. You could definitely feel that the back end was higher but there were certainly no vicious tank-slappers or terminal instability, in fact the whole plot (if anything) felt more stable than previously. I'd been worried that I would turn the bike into a nervous, twitchy thing, but if anything it felt more planted than before I'd made the changes.

I did a full double check around the back of the bike to see if anything was fouling due to the increased ride height, but everything came up with a clean bill of health. The only thing I had to change was to unwind the rear drum brake adjuster as the lengthened shock had caused the rear brake mechanism to use up all of its travel. Apart from that all good...