SP: Spring Boxes (Rear) Thornton coil over spring rate.

Dave Hulstone

Well Known and Active Forum User
VOC Member
Hello all. I am very interested to find out what the consensus of opinion is regarding the spring rate of the rear Thornton coil over spring on a Comet? Laney supplied mine with a 260lb when I told him I weighed around 80kg with my clobber on, rarely take a pillion or carry luggage and am running the standard series C setup with the friction dampers. I have had mine on now for about 4000klms with a small cable tie fitted to give me an indication of travel being used, I have had to put quite a bit of extra pre-load on to keep it from been buried in the bump stop. The result being my rear stand is no longer kicking up slightly when it’s parked, but level?
I don’t see this very often on a Comet. I am thinking off having my spring rate checked by a spring supplier and going up a rate and lessening the amount of pre-load but before I do I would like to hear your valued opinions.

Dave.
 

davidd

Well Known and Active Forum User
VOC Member
Dave,

I don't think that AVO will be much help with the Works Performance springs, but you never know. I think it is important to know exactly what you have.

Rear Coil Over Springs.PNG


You are a pretty light rider (176 lbs)to be bottoming the heaviest spring. If you can measure the wire and count the coils, you should have an answer.

David
 

Dave Hulstone

Well Known and Active Forum User
VOC Member
Hello David. I should have known you would be the guru with this. I’m in good hands. I have just measured my spring dimensions and it’s definitely a 260lb, which until now I thought to be a ‘soft Comet’ spring, although I know the great Greg Brillus runs a 260lb also on his Rapide so I should have been suspicious. I must be reading my marker wrongly. As you say, there’s no way me being a light weight with no passenger or luggage I could be bottoming out. I need to speak to my friend Martyn Goodwin who also rides a Comet with a coil over but weighs in at least 200lbs, before iso, to see what he’s running, although the last time I followed him the only time it was off the bump stop was as he crested a hill. (Not sure how he bent his top axle )
Thankyou David. You are a font of knowledge. I will get a 215lb from somewhere and start again.
8DB00876-60A9-47DA-9A0F-224EA0CA748D.jpeg
 

Dave Hulstone

Well Known and Active Forum User
VOC Member
David, I’ve been thinking a lot about this. I definetly can’t go softer with my spring. There is so much travel at the minute I have to have my chain like a dirt bike chain or it restricts my travel. I’m going to back my preload right off and measure it in case it’s been creeping back.
 

davidd

Well Known and Active Forum User
VOC Member
No, I did not think that you could go softer, You just needed to check where you were. If you are overwhelming the 260, you do need to go higher. I would not be afraid to use all the preload and I will see if there is anything higher.

"Dave" in the note is David Malloy.

David
 
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