Soft tail conversion

[CJC]

Hi all I am looking for some advice about soft tail conversion of my wife's trike. As it is a bit on the hard side for the type of roads we use. The trike has a full IRS system other than the locking bars fitted to make it a hard tail. After removing this bar I tried fitting a set of Harley 1200 shocks unfortunately they appear to weak as the trike bottoms out instantly. I may be fitting the shock wrong and would be grateful for any advice.
thank you for reading my first ever post.
regards chris

 

[Loner]

Can you give us some dimensions (eye-to-eye length, width of mount point if enclosed)? Maybe we can suggest a coilover set that will fill your bill.

 

[CJC]

Hi loner thanks for your quick response to my post. The eye centres are 350mm and they attached on one side only. Can you give me an idea as to what an over spring is and how it works. If you have any pictures they mat help me to understand. Thank you once again I look forward to your reply.
regards chris

Can you give us some dimensions (eye-to-eye length, width of mount point if enclosed)? Maybe we can suggest a coilover set that will fill your bill.

- - - Updated - - -

Thank you for your welcome I await with baited breath any responses.
regards chris

 

[Mrmri]

Did you put the 1200 shocks under the bike in the original place of the shocks or on the IRS? The original placements the shocks work opposite of a conventional shock and would bottom out right away. Just my $.02.

 

[CJC]

SoFt tail

Did you put the 1200 shocks under the bike in the original place of the shocks or on the IRS? The original placements the shocks work opposite of a conventional shock and would bottom out right away. Just my $.02.

Hi put them in the original position set at 45 degree angle out to the irs on each side.
regards CJC

 

[Phu Cat]

What about calling a couple shock manufacturers, telling them what you'd like to accomplish and giving them your measurements, and see if they can make a recommendation?

PC

 

[Loner]

OK, humor me for a few of your minutes and let me see if I can add anything usable here :cxtv: . Let's approach the problem through a logical sequence to see if we can yield any help toward a solution.

First, we need to separate the functions of the hardware we are considering. A shock lends virtually nothing to supporting weight on a vehicle. A shock is a ride dampener which adds a controlled bit of resistance to quick extension/compression strokes thereby smoothing the dynamic ride of the platform (in this case, trike). The second function is that of a spring - that is the load-bearing hardware of your suspension setup which has its rating beginning in a static measurement. On a motorcycle, the two functions are often combined with the shock absorber in a conventional cylindrical form encircled by a winding spring coil around the outside which acts as the spring. The set of these two is generally referred to as a 'coilover shock'. Integrated hardware, but still two distinct functions. The coilover shock is the type used in virtually all Harley configurations.

With that said, let's look at your specific design. Convention would tell us that if you install basically the same shocks that came on the bike before conversion then it would only need a ramped up spring rating to suspend the additional weight added by the trike framing and body. However, you say that you have now mounted the shocks/springs at a 45 degree angle to accomodate the IRS. So, we go back to the drawing board for some more geometric physics (sounds daunting, doesn't it?). A spring's rating is established and measured in a vertical plane, or 90 degrees from the horizontal plane of a motorcycle's platform. For every degree of tilt (moving by degree from 90 to 0), the spring's effective strength is diminished by a proportional amount. So, if you tipped the springs from their stock angle of maybe 10 degrees to 45 degrees, the strength of the spring would be effectively diminished by about 44% and then add to that the extra spring strength required for the additional trike body weight, and it is no wonder that it collapsed when the 1200 springs were installed. Possible solutions? First you could get technical data about your suspended weight over the rear wheels, design sketches and dimensions, etc. and let a professional spring manufacturer provide you exactly what you need ($5-600 US for a pair of chrome/polished coilovers). I have worked with Aldan Shocks here in the US in the past and have always gotten a successful product. Or, you bring your spring rates up to the needed range by doubling your capacity by using two matched HD coilovers on each side.

My most important statements of all - All my babbling above was predicated on a very few stated facts, and there is great potential that I don't have those facts correct in my tiny mind. Before anything is done tangibly on this project, much more information should be revealed. Conversion type for the trike differential/suspension, a good sketch of the shock mount points (stock and modified), how much suspended weight is now on the rear suspension, etc.

Sorry for rambling, but I get lost in trying to put my deranged logic to paper. Some of this stuff I can hardly reread and understand where I was going. So fellow forum techies, please try not to totally crucify me - read for what it's worth and go on to something more interesting. I often wish some of our fellow members could just line up outside my garage and let our techie teams get together periodically and provide some hands-on solutions - that's what I enjoy most! :xzqxz: