Has anyone taken out a Low Rider or Street Bob fork spring? I’m not entirely displeased with the dampening of the DBV forks, but I need higher rate springs for my fat ***. So instead of dropping the grand or so on Ohlins carts and springs, I’m thinking about simply swapping the stock springs for some racetechs.

But I need to know the length of the stock springs. Yes, I could open up my forks and measure, but I’m lazy and it’s easier to ask here first.

So so let me know if you know.

Thanks.

 

I have not taken my springs out. I'm about 225lbs which is heavier than the average they design bikes for. My FXLR front end seems stiffer and higher than what would be ideal. I have no complaints about the damping. My theory is that the oil level was slightly overfilled on mine. There are three ways to stiffen up a front end,
1 higher rate springs
2 preload spacer
3 higher oil level (increased air spring)

 

What I’m hoping to accomplish is finding out the dimensions of the stock springs and seeing if Racetech has a set or can make a set for my weight and drop them in.

Otherwise I think I have a set of adjustable preload 49mm fork caps that may fit. I suppose I could try them out.

 

43.5mm (OD) x300mm 1.10kg Spring rate

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These are the things you need to know about only:

1. Outside diameter of the springs because, unlike a cartridge system HD uses the ID of the fork tube to captivate the spring. That is what prevents the spring from kinking. Unfortunately your springs are always rubbing against the fork tubes producing micro steel partials that pollute your fork oil to assure premature wear.

2. Spring rate.

3. Adequate stroke with your spring pre-load added to the LOA. ie: Stroke 130mm (example of your fork capability) + spring pre-load to add to get your sag + add safety adjustment length. You than make up the difference with a spring pre-load tube. An adjustable fork cap is a good thing so you can tune your forks while on the road for changing road conditions.

~~~~ or ~~~~~~

Simplify but you would have to use your head and skill to think outside of the box.

Use a sport bike set of fork caps by buying a set of bent/trashed forks that have the correct fork cap OD for the 49mm fork tubes. Use the center damper rod receiver in the fork cap than make a damper rod. Make a piston with a replaceable piston ring (buy the Teflon ring). Get your spring pre-load tube and size it to your piston ring by taking this to a machine shop that can hone. Once the piston length is known, make a Delron spring guard and size the available damper rod length so your spring can not kink and can not rub on your ID of your fork tube. Make a seal head to limit the rebound length. Install a top out spring below the the seal head and above your piston on the damper rod shaft. Make sure you have enough length to allow for an adjustable compression valve found commercially of your choosing. Make two spring pre-load mounting adapters for the spring pre-load tube. Make the top spring pre-load adapter to allow for the adjustable pre-load fork cap mechanism to apply pre-load to the spring. The spring is what keeps everything tight enough with your body weight. Depending on the quality of your design & machine shop, your results make for a much better fork for the $25 ~ $30 for materials and the price of your new springs. This does not include your time to fabricate as this is a hobby. I did the first prototype exercise for HDF member mosterblaster. Have fun.

 

Hi Howard. Those are the stock spring dimensions for the new softails? Can you order springs like that but at 1.25 or .30? (That’s what Racetech specs their Dyna springs for my weight). Saving for a house and don’t want to drop the grand on the FKC carts at this point Am looking for a less expensive solution for a year or so.

Thanks.

 

What are you talking about (1.25 or .30) what? 43.5mm (OD of the springs) x300mm (length) 1.10kg Spring rate.

 

1.25kg spring rate is what I need for my weight according to a chart on RaceTech’s site.

 

Just ordered springs from RaceTech. Happily I found in my closet a pair of Burley Brand 49mm preload adjusters. I'll use them as well.

Ordered a 30mm socket for the Burley's and a 1 3/8 for the stock caps. I'll probably line them with painters tape to try and minimize the scuffing of the black preload adjusters.

Lastly I'll need to make new preload tubes for the new springs and to compensate for the preload adjusters. Anyone know what size PVC tube I need?

Thanks