Lowering rear end....help

Tim5779 · 08-20-2012, 10:33 AM

This may or may not be a stupid question, but does anyone know the spring rate of the rear spring? I know low and mean sells a rear lowering spring for roughly $190, but my thought was...can't I just buy a common die spring that is 1.5" shorter than stock, with roughly the same spring rate??? I'm an engineer by trade so this is the sort of thing I try to avoid, paying way too much for something I can make. I can buy a die spring for roughly $25...sounds like a no brainer to me, unless I'm missing something???

abonet · 08-20-2012, 11:13 AM

i took one of my stock springs and had a local machine shop take .125 off each end and it gave me 1.5 inches in back. keep in mind that the lenght doesnt change that much because you are at a pinion angle so lenght of swing arm plays into effect on mono shock application.

Tim5779 · 08-20-2012, 01:03 PM

wow, so taking .25" off gave you the 1.50" in the back? that's a heck of a ratio. do you have any problem with bottoming out or anything like that? i had thought of just modifying the stock spring as you did but was worried because that would definitely decrease the spring rate a little. Maybe that just makes for an easier ride?

abonet · 08-20-2012, 03:24 PM

i have not seen any change with over 4000 miles on it. remember 17th of an inch equals 1 degree. so across 15 inches of swing arm that = 1.470 drop.

Tim5779 · 08-20-2012, 05:07 PM

NICE...thanks alot abonet! That calc looks right to me, I'm definitely going to try this. I'll keep you posted.

cordkc · 08-20-2012, 06:35 PM

Quote:

Originally Posted by abonet

i have not seen any change with over 4000 miles on it. remember 17th of an inch equals 1 degree. so across 15 inches of swing arm that = 1.470 drop.

Hi Abonet
I am no math guy, so help me out here. If 1/17" = 1.47" drop, why did 1/4" = 1.5" drop on your mod. I am not asking to be a smart ass, I was thinking about slipping in a 1/16" washer on top of my shock in hopes of adding 3/4" to the height of my seat ,so I wanna try to understand the math.
Cheers

Sent from Gotham Asylum

abonet · 08-20-2012, 08:49 PM

No each angle equals .017 of an inch so by taking .250 off it changed the angle of the swing arm lowering it by 1.5 so yes if you put a spacer under it will go up .125 should take you up 3/4 of an inch.

cordkc · 08-21-2012, 02:28 AM

Thank you for the clarification. I will give it a shot,,, and will post how it worked out.
Cheers

Sent from my A100 using Motorcycle.com Free App

endres1979 · 09-04-2012, 11:52 AM

Hey Tim, did you shorten your spring yet? Abonet, do you ride with a passenger? If not, do you think a passenger would effect this mod?

Tim5779 · 09-04-2012, 12:57 PM

I did, it worked like a charm. I took the spring off and threw it on a surface grinder, took 1/8" off each side, threw it back on, and low and behold i just saved $200 (low and mean spring). The ride IS a little easier, and I haven't had any issues with a passenger. I've went over some pretty heafty bumps with a passenger and all is well. If it makes you feel any better, I did the calc for the stock spring rate, and as long as you keep the spring cool during machinging the rate will not change (the 1/8" off each side will not affect it). I've also read somewhere in here that there are safegaurds built into the bike that will not let the tire bottom out on the fender...I don't know if that is true or not, but I've read it a few places. Hope this helps, but in my opinion...this mod is well worth your time.