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Laney Thornton suspension

davidjoyner

Well Known and Active Forum Website User
Non-VOC Member
Does anyone have a copy of the assembly instructions for laney Thornton units. I bought mine in '97 and have been riding it ever since. Last few years have started touring with panniers etc and the rear bottoms out. This really began after taking the friction dampers off and putting new seat stays on to the footrest plates. I was sent a rear damper piston mod by Laney but never installed it. Upshot is I'd like to now and have got a box of bits and various springs that I can't remember what to do with! Would also like to reduce the friction on the spring boxes as they are trying to cock. Any one have any experience of drilling air holes in the rear springboxes? Incidentally the suspension has done about 20.000mls without any problem and it is a big improvement on Stevenage's originals
 

clevtrev

Well Known and Active Forum Website User
VOC Member
You will not reduce the friction in the springboxes, because the springs are compressing through an arc, so will always be forced outwards. The job of the springbox is to control this. All you could do is line the box with an anti friction material, nylon for example.
 

davidd

Well Known and Active Forum Website User
VOC Member
Yes, I can email you a copy. There is an inner spring that is left wound, assuming the outer spring is right wound. You can add one or one in each spring box to increase the spring rate. I will PM you my email.

David
 

Robert Watson

Well Known and Active Forum Website User
VOC Member
When I lined my rear spring boxes with nylon, to a reasonably tight tolerance, the following happened.

On the way home from a rally, about a 350 mile run, we get to about 60 miles from home, when she starts to complain about a rather rough ride. Just getting a bit tired says I. I'll have a look when we get home. Next day take off a spring box and try to pull it apart. Not going to happen. Clamped one end in the vise, hooked the crane on the other end, picked up a rather heavy bench. Oh dear. Managed to finally persuade separation. Ah, the penny drops --- 300 miles in pissing rain, and nylon is hygroscopic. 15 thou clearance is now about 10 thou interference.

New liners made in UHMW polyethylene. Been in there now some 15 years or more.

Don't use nylon with any kind of tight tolerance.
 

vibrac

Well Known and Active Forum Website User
VOC Member
What are spring boxes?
DSC00284.jpg

:eek:
 

davidd

Well Known and Active Forum Website User
VOC Member
Have you got any idea as to why they do not buckle under compression, not enough movement or what?

I had a buckling problem. I made a extended inner spring boxed for the rear so that the Thornton springs would work properly because they were so much longer. I was racing at Deland and I came into the pits and Sam Manganaro noticed that the left side inner spring box had come completely off the the end of the spring and cocked. I put it back on and checked the other side and found that the inner spring box had worn through the top of the outer spring box and as it went through its motion it was sticking on this metal to metal contact. This was seemingly caused by the added bending of the longer rear springs. After the race I set about making a coil over. I decided that the springs and spring boxes were too much, too high maintenance and too heavy. On my street bike I used a UHMW slip ring to steady and hold the box in place with the longer springs. Justin MacKay-Smith made these for a few years about 15 years ago and they were quite good at the job. A few years later, Thornton started making coil over rears and this is the best solution for the rear suspension. I understand that many prefer the stock look instead.


David
 
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