• Welcome, Guest! We hope you enjoy the excellent technical knowledge, event information and discussions that the BMW MOA forum provides. Some forum content will be hidden from you if you remain logged out. If you want to view all content, please click the 'Log in' button above and enter your BMW MOA username and password.

    If you are not an MOA member, why not take the time to join the club, so you can enjoy posting on the forum, the BMW Owners News magazine, and all of the discounts and benefits the BMW MOA offers?

  • Beginning April 1st, and running through April 30th, there is a new 2024 BMW MOA Election discussion area within The Club section of the forum. Within this forum area is also a sticky post that provides the ground rules for participating in the Election forum area. Also, the candidates statements are provided. Please read before joining the conversation, because the rules are very specific to maintain civility.

    The Election forum is here: Election Forum

Progressive Fork Springs...seem stiff

R

rbryson

New member
After years of weak and diving fork springs I finally (and happily) upgraded to Progressive. Bombar Beemers did a great job! No more diving, but forks seem stiff, even though they do a good job of keeping the rubber to the road. I put in the full spacer and am wondering just how much a difference I would feel if the spacer were cut in half. I prefer a smooth ride, but don't want to sacrifice too much handling. I am a 55 year old teacher, not a racer, so that should tell you something about my riding style. My question is, do most people that convert from stock to Progressive springs use the full spacer? Thanks in advance for any opinions.:wave
 
On my airheads I usually cut the spacer in half (through the center, not lengthwise!):) even with a jammer hanging on it and been very happy with the setup. I found that is was too stiff with the spacer at stock length.

RM
 
#7.5 by mixing #5 and #10 equally. Guess I could replace with #5 to reduce stiffness. Thanks for mentioning the fork oil weight. I had overlooked that simple solution completely.
 
You could also try reducing the fork oil volume a few mms. If you're going to change oil anyway, I'd start with a volume that is maybe 15-20 mm lower than requried. After trying that out, you could add a little bit, 5 mm or so. Try that out, etc. Easier to add than take out!!
 
cutting the spacer in half will help, pre 81 forks will do great on 5wt, as in all older forks when were they last taken apart ,cleaned and had the bumpers renewed?
 
I installed Progressive springs in my R80 about a year and a half ago. After the rebuild I initially thought something might be wrong. When I took it off the center stand with the old springs, the bike would "bounce". When I rolled it off with the Progressives installed, it felt like the forks wouldn't move, at all. I also used the full spacer. I have found they have loosened up a little bit, but not a whole lot. I've heard a number of comments on the Airheads list about the springs being too stiff, though. Personally I'm rather happy with them, but I ride my R80 pretty hard and I'm only 29. The bike does stay planted very well, though.

I'm not sure changing the fork oil will make a big enough difference. I'd go for cutting the spare in half, or you could also try to eliminate it, completely.
 
Spacer dimensions are going to primarily impact suspension sag (how much suspension drops from resting position when you climb aboard the bike). IIRC, sag should be about set to about 1.6", both at front & rear. (if someone else has different numbers, please post).
Sag needs to be set correctly before any other facets (compression and rebound damping) can be addressed. Compresion damping (how quickly the fork compresses upon impact) is adjusted by oil weight, oil amount and number & size of holes in the damping rod, as well as by spring characteristics. Rebound damping (how quickly forks extend back after being compressed) is addressed primarily by the oil & hole characteristics.
Set sag first, then be sure that all mechanical conditions are correct. Once you're good there you can start digging into minor/major adjustments via amount & type of fork oil, modifying or changing damping rod, etc.
Were the springs purchased by you, and are they the proper ones for the weight of you and bike and gear?
 
Are you sure that isn't 1.63" ;) What I've read is that the sag should be between 2.5 and 3 inches, measured with the wheel completely off the ground and suspension fully extended, to the point where you're sitting on the bike, with gear and a tank of fuel. You can put a plastic zip-tie on the stanchion when off the ground, then see where it goes to when you put it back on the ground and return to on the center stand again.
 
20774 said:
Are you sure that isn't 1.63" ;) What I've read is that the sag should be between 2.5 and 3 inches, measured with the wheel completely off the ground and suspension fully extended, to the point where you're sitting on the bike, with gear and a tank of fuel. You can put a plastic zip-tie on the stanchion when off the ground, then see where it goes to when you put it back on the ground and return to on the center stand again.
Click to expand...

there are actually 2 sag settings. one is the difference between wheels off ground (suspension extended) and bike standing upright, unladen (suspension slightly compressed). the other is "static sag" and that is the difference between bike unladen on wheels and bike in ready to ride condition (with rider and gear on board- suspension partially) I think the 2.5 to 3" you mentioned is a combination of both settings, and the 1.6 (or so)" i mentioned is just the static sag setting.

one of many writeups on the subject..http://www.sportrider.com/tech/146_0006_sag/index.html
 
something that happend to me, put in progressive springs ( and nos konis on the back) when I put the springs in , I also swithced to a heavier oil
guess what,
I think it was too much for the "system" as then I developed a fork seep
what should I guess, its a 30 year old system and I just bumped it up a bunch
this winter project........replace all the seals in the forks
but all that said, the above stuff and a tellafix brace made the bike a totally differnt bike and I am happy with the changes
 
I just replaced the original springs with progressive on my R75/7. It transformed the bike, reduced the braking dive to almost nothing and improved the handling.

We were at a BMW open house and they had a suspension specialist. he rocommended the heaviest fork oil I could get. I used #15. I thought it would be to heavy but it seems fine and I am enjoying the bike even more
 
Progressives

Rbryson:

I used to own an extensively modified RS, and when the Progressives / Konis (f/r) went in, it was very stiff. I got used to it, the bike handled very well, and the springs eventually softened up.

Rinty
 
I bought an RT allegedly with Progressives in the front forks. The handling felt off, so i did the billet upper triple, and really greased up those steering head bearings. Now it handles like a whole new bike.
The heavy Progressive springs, i think, do not make up for that flimsy upper triple
 
What type bike to do you have? It's best to always list your bike and year when asking for advice. Most of what I've read, riders on naked bikes find progressive springs stiff; however, the springs are good for with farings. I have an 88 R100RT, and I find the progressive springs adequate. As far as the spacers go, I shortened the spacers to make the overall length (spacers and springs) within the preferred range as indicated in Clymers.

Also, did you make sure there is no stiction with the forks? See the following link for a quick and easy way to test for stiction.

http://w6rec.com/duane/bmw/stiction.htm
 
Fork alignment

I have read the Randy Glass article on fork alignment. I have no doubt that proper alignment is critical to a good ride, but his proceedure seems excessive. I also remember reading a more "quick and dirty" approach to fork alignment where elements of the triple tree, fender brace and axle were loosened and retightened in a certain order, bouncing the suspension in between each tightening. Is this generally adequate? Any one remember the thread where this was posted?
Thanks,
Theo Marks
'74 R75/6
'01 1150GS
 
Theo -

I don't recall a specific thread here or in other forums, but I've always done the "quick and dirty" as you imply. With everything assembled with loose fasteners (large axle nut tight but not the pinch bolts), I've done the bounce process and then tightened the pinch bolts at the lower triple tree. Bounce again, move down to the fender bolts. Bounce one more time, tighten the axle pinch bolts. I've not had any problems with stiction...that I'm aware of...

One thing to be aware of is that when tightening the fender bolts, there shouldn't be any tendency to draw the forks or fender one way of the other. It may be necessary to add, subtract, or move washers on either side of the fender so that it's a good fit. Otherwise, during the tightening process, you'll be putting undue stress into the sliders.
 
put progressives in the tubes of my old 83 R80RT. felt like a friggin' dirt bike. replaced with h/d bmw units, much better.
 

Attachments

  • DSC01477xx.JPG
    DSC01477xx.JPG
    115.7 KB · Views: 100
I put the Progressive Springs in my 86 R80 and felt that they were much better than stock, but also too stiff. I did cut the spacer down incrementally until the circlip just touched the spacer with no load. Since the springs are progressively wound, the preload takes out the softer part of the spring first. Cutting the spacers down certainly helped and the bike has a good sporty feel.

My next experiment will be with reducing the amount of 7.5 wt during this winter's fork oil change.
 
You must log in or register to reply here.

Similar threads

gtgt_bangbang
Race Tech Cartridge Emulators "gold valves". Reading list & my set up (78 R100 )
Replies
9
Views
941
kbasa
kbasa
gtgt_bangbang
fork brace fork clamp - installation notes
Replies
1
Views
617
gtgt_bangbang
gtgt_bangbang
L
Progressive Fork Springs, suggestions and experience. 1986 R80
2
Replies
23
Views
4K
20774
20774
P
Mild to moderate lowering of a 2019 R1250GS Adv.
Replies
9
Views
1K
armycopter
armycopter
mhines
r1100s windscreen replacements
Replies
11
Views
576
mhines
mhines
Back
Top