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Brampton coil-over damper.

Albervin

Well Known and Active Website User
VOC Member
Very informative gents. From memory I have a 130 or 140lb spring mounted over a modified Koni. It is mounted onto the headlight stay bracket. My original girder link had a reinforcing plate brazed on but my new (post crash) one does not. Mike Breeding was quite happy to say his links will withstand the forces so I feel confident in that area. The coil over has been fitted to the Rapide for over twenty years although it was slightly altered when I purchased the bike. The previous owner rode it across Australia in 1997 and I have probably put nearly 20,000 miles on it since. As you can see, there are some differences between it and the Thornton unit.
DSC00001.jpgDSC00007.jpg
 

Peter Holmes

Well Known and Active Website User
VOC Member
I was always under the impression that the main criticism levelled at the Koni damper was that it was really to stiff to operate well with the Girdraulic fork, even in the early days when you could purchase a softer version for the front, and set to the lowest setting, did it work well with the Brampton forks, I guess the answer is yes or you would not still be using it. I have two of the Koni 76F1239 dampers and did a deal with a brilliant Vincent owning engineer who was going to convert the two dampers for use with the Brampton forks, keep one for himself FOC and return the other back to me fully converted, unfortunately the dampers were returned to me as for some reason the work could not be done satisfactorily, do you know who did yours?
 

Albervin

Well Known and Active Website User
VOC Member
Peter, I certainly do know who did mine but sadly he has passed away. I was always taught soft springs and firm damping. This has worked well for over 20 years. I do not know what setting the damper is at but the springs are only about 130lb as against the standard 180lb for and "A" or "B". The new forks seem to be a bit stiff at the moment but I hope they will bed in over the next couple of hundred miles as the bushes settle.
 

Oldhaven

Well Known and Active Website User
VOC Member
Rather than hijack a recent thread Albervin has started to assess interest in building a few of his version of a Brampton coil over, I will move any more discussion of the Works version I have here. Here is a picture showing the area of the rod where the fracture occurred. As you can see, turning the 1/2" rod down to use a 3/8-16 thread removes a lot of the strength of the rod, and if you consider that the minor diameter of the thread is just under .300" that is a lot of strength gone, (plus the stressed area at that corner).

Quite a few of these Works Performance units are used as Thornton versions on C and B Vincents front and rear, and other Brampton applications have covered thousands of miles with no difficulties. As far as I know mine is the only one to have failed other than one instance described of improperly locking up the mounting so it could not rotate. My mount was bushed and double nutted so it could freely rotate. I can only think that I may have overlooked something like the clearance of the Works spring seat to the Brampton spring lug or something obscure.

With my apologies to Ted Leno who I think drew it, I have posted the drawing he did of the conversion. since Works went out of business I don't think we will see many more of these adaptations.

IMG_1732.jpgbrampton damper001.jpgIMG_1733.jpg

I so liked the improved ride of the conversion that I am going to give it a try again by repairing the Works shock, but will make my own damper rod of a much higher grade of stainless and will thread it either 1/2-20 or 12mm to preserve more of its integrity.
 
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oexing

Well Known and Active Website User
VOC Member
Looking at your type of dampers I would not want any Clevis ends on my dampers at all. How can you know that all bores for the Clevis screws are dead parallel to each other ? If not so your damper will get side loads resp. bending loads on the damper rod - which is bad for the rod but more so for all seals inside ! I do not believe the crack was only due to blocked rotation in the clevis end but possibly from bending load from questionable components with their bores. So as mentioned elsewhere I will definitely have spherical bushes in the damper ends like is standard in Fournales air shocks and the clevis type on the Brampton forgings - not like here shown just wrongly designed. Remember, most typical shocks got rubber/steel bushes in the damper ends exactly for this reason so I would not want to keep the same flaw when repairing the strut.

Vic
 

Gene Nehring

Well Known and Active Website User
VOC Member
Has anyone tried to come up with a twist on bottom clevis to mount to the existing spring attachment point?

It seems to me that in terms of geometry and strength it would make sense to try to use the factory mount?

Interested in thoughts.
 

Albervin

Well Known and Active Website User
VOC Member
Has anyone tried to come up with a twist on bottom clevis to mount to the existing spring attachment point?

It seems to me that in terms of geometry and strength it would make sense to try to use the factory mount?

Interested in thoughts.
If you go to the new thread there is more information there. Clearances are very tight. I also doubt there is any significant difference in stresses between the claw and the headlight mount. Take a very close look at that area and there is a lot of metal. Anyway, after twenty years and no dramas I can only say it works for me.
 

Oldhaven

Well Known and Active Website User
VOC Member
For future reference here is my Brampton/Works spring over conversion prior to assembly after I made a new piston rod and lower spring mount. I used 17-4 PH H900 ground and polished rod using a 1/2-20 thread to replace the smaller portion of the original rod that snapped. The spring seat is thicker than the original that disappeared during the incident, and has no assembly slot since the spring can be changed by removing the upper spring seat and lock ring. The spacer on the rod is to limit travel so no interference with the Brampton structure can happen at full extension. The clevises are slightly modified products from Midwest Control Products Corp.


233666AD-1153-46B0-877B-42929C475407.jpeg
 

Mike T

Well Known and Active Website User
VOC Member
Hi, here's a video that Ted Leno posted back in 2010 of his Brampton coil over . I also have some clips of the unit on his B Rapide with Brampton's if you would like to see. Just let me know and I would be happy to post. Cheers, Mike

 

Albervin

Well Known and Active Website User
VOC Member
For future reference here is my Brampton/Works spring over conversion prior to assembly after I made a new piston rod and lower spring mount. I used 17-4 PH H900 ground and polished rod using a 1/2-20 thread to replace the smaller portion of the original rod that snapped. The spring seat is thicker than the original that disappeared during the incident, and has no assembly slot since the spring can be changed by removing the upper spring seat and lock ring. The spacer on the rod is to limit travel so no interference with the Brampton structure can happen at full extension. The clevises are slightly modified products from Midwest Control Products Corp.


View attachment 41673
From what I see the upper and lower mounts are not bushed.Yes? No?
 
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vibrac

Well Known and Active Website User
VOC Member
Has anyone tried to come up with a twist on bottom clevis to mount to the existing spring attachment point?

It seems to me that in terms of geometry and strength it would make sense to try to use the factory mount?

Interested in thoughts.
Yes my coil over uses the original clevis so a coil spring could be remounted plenty of pics on here (use search)
I have it on my Comet I no longer worry about medium potholes and with a rear coil over its a very good set up
 

Oldhaven

Well Known and Active Website User
VOC Member
The upper mount uses a girdraulic pad bolt in the clevis, (I forget the number). It is threaded into one side through a tight clearance in the other side and is locked solid with a nut since the shock body is bushed from the factory at that place. There are two oilite bushings in the lower clevis mount, but nothing in the Brampton headlight bracket/mount. The double nutted pivot bolt is shimmed to a close fit to the bracket with brass washers. The original lower spring mount is still there so The Brampton spring can be refitted if desired, and I have it on the bike now until I get around to refitting the coil over. There is little rotation in use, but enough to warrant bushings.
 

vibrac

Well Known and Active Website User
VOC Member
Here is a general picture of my unit I think the originators did not think that a headlamp lug was not man enough to take a full bump hit having seen what happens when a normal spring breaks I would rather be safe than sorry
1619426667961.jpeg
 

vibrac

Well Known and Active Website User
VOC Member
Its the stop light pull on the front brake beam. Stuff the back brake one, (Dont belive them when they say tthe series D was rubbish it did get at least one thing right! :eek:TIC )
 

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