Bonneville America Forums Forums Technical Forums General Tech Progressive Spring Install

OK all, I just got my Progressive springs in the mail. I want to do the swap early next week and want to change the fork oil too. Does anyone know what weight to use, and how much to put back in with these springs? I understand that they displace more oil than the stock fork springs. Any assistance will be appreciated, you guys haven't let me down yet!

Sorry to be blunt, but do a search. Pretty sure you'll find what you are looking for.

fork oil type, kayaba G10
fork oil capacity bonnie & T100, 484cc. speedmaster & america 548cc
fork oil level (fork fully compressed), bonnie&T100 120mm below inner tube upper surface. speedie& america 166mm below inner tubeupper surface.
as per the service manual, hope this helps

Wyrm74,
The job is pretty easy and straight forward. Just have someone hold the bars out of the way and it goes easier. Takes all of 15 minutes if your oil is nice and clear still.
Remove the two large caps on the tops of the forks, they are spring loaded so beware and hold on. Once you get the cap off, take a metal coathanger and bend a little hook in the end of it. Reach down inside the fork and hook the old spring and lift it out slowly, as not to spill the oil all over like I did. Check the color of the oil, if it's clear it's good still. Notice the positioning of the springs and spacers for reinstall. Put the new spring in with the compressed/tighter wrap spring part down in the bottom of the forks. Reassemble, tighten cap nuts and ride.
If you are going to change the oil, suck it all out with some vinyl tubing stuck on the end of a turkey baster. Cheap and easy to do. Then pour in the desired amount of oil, and check the oil height with a dowel rod stuck down the forks as a measuring guage. Get them both the same hieght (whatever the measurement is, mentioned above) and you're good to go.
By the way, there has been a lot of talk in the NTBF about this and they seem to think that a 50/50 mix of 10 and 15 weight is the ticket with the front progressive springs.
Good luck.

Yeah, I did all 10W, when I had the springs put in, and sometimes I get the feel that maybe it could be a little stiffer, especially now that those EBC HH pads give me so much dive under a good brake.

Ditto here, I have the EBC rotor and pads, and they grab!! I never changed the fork oil, it's on my winter list at this point unless I get bored at Pat's. He'd gonna have a 50gal drum of hazerdous waste by the time we're done with our mods and clean up after Yota.

I'm going to try to do it this Wednesday, and I'll let you know how it goes. Thanks for the advice everyone!

All right fellas, I must've done something wrong but I don't know what. Got everything apart, and the fork oil was a little cloudy/murky. Decided to change it, picked up 10w and 15w to mix at 50-50 and sucked all the old oil out. Put in the new oil and...the forks won't re-extend. Bike up on the jack, plenty of clearance between bike and floor. Tried everything, even taking the springs and spacers back out to try and extend those suckers. Nothing. My forks are stuck fully compressed and they won't budge. Could there be too much oil in there? The manual says that the level should be 166mm from the top of the fork when fully compressed. Unless my math is off (actually, my friend's math cuz I wouldn't even try to figure this out)that should be about 6.5 inches from the top of the fork tube. Well, that's what it is. I'm stumped here guys, any ideas? I hope it's just something stupid so feel free to let me know your thoughts. Jeepers...I can make anything simple into a fiasco...

Try sticking equal length broomsticks down the shocks and give them a whack with a 2x4 placed across both at the same time. Make sort of a "pi" symbol with them. Of course this is with no springs/spacers/washers in them. The oil is ok, just add a few cc's when done to each fork to compensate for the oil that will stick on the forks when done.
Just an idea. Can't really be too serious, probably just topped them out and the seals are holding/binding ever so slightly.

Dinqua rules! Thanks Pat! I actually used 1" dowel rod, a 2 X 4, and a dead blow mallet. 3 whacks and down they slid. I re-adjusted the oil levels in each side, put them back together, and went for a ride. I have to say, the new springs don't just soak up bumps better, the whole bike handles better. Cornering is now very similar to my buddies T100. It will never be as "quick" handling as his bike, but I gotta tell ya, my confidence sure is higher. I never even knew it was low! I guess it just seems like the front end is stiffer and much more stable. I used a 50/50 mix of 10 and 15 weight fork oil and that seems to be the ticket. I am much happier with the way my bike handles now. Rear shocks are next!