Progressive Fork Springs, suggestions and experience. 1986 R80

[ltbiker]

Want to curb the front end nose dive when breaking. Also I am overweight so stiffer springs make sense. Progressive, Wilbur, Boxer2Valve etc. all have progressive fork springs. Anyone have any experience with them? The late model forks have the circlip holding the spring and wondering how difficult they make the job.

 

[pglaves]

Want to curb the front end nose dive when breaking. Also I am overweight so stiffer springs make sense. Progressive, Wilbur, Boxer2Valve etc. all have progressive fork springs. Anyone have any experience with them? The late model forks have the circlip holding the spring and wondering how difficult they make the job.

You probably need stiffer springs. But if that were my bike I would add 15cc or so to the fork oil in each leg. That reduces the volume of the air above the oil. So the air compresses more as the forks compress. This air spring component can significantly reduce dive but have little effect on the reaction to small bumps, adding to rider comfort. Try it.

 

[stevenrankin]

First

I would first try out Paul's suggestion. I wish someone had made it back years ago when I upgraded my front suspension from stock to Progressive springs. Mind you, I love the progressives, it took a bit of fiddling with the PVC spacers to get the right amount of preload, but they work well.

Getting back to Paul's suggestion, if someone had at the time of my change over, suggested his method to solve my problem, I would have jumped at it first rather than spending the money on new springs. If his suggestion of adding extra fork oil had not worked, then I would have purchased the Progressive springs.

So much information is now available on the internet and the forums have improved so much in the past years, information like Paul's is becoming much easier to access and distribute. A win, win for all of us. Good luck on whatever you decide to do. St.

 

[ltbiker]

You probably need stiffer springs. But if that were my bike I would add 15cc or so to the fork oil in each leg. That reduces the volume of the air above the oil. So the air compresses more as the forks compress. This air spring component can significantly reduce dive but have little effect on the reaction to small bumps, adding to rider comfort. Try it.

Thanks that seems a quick, easy and cheap fix. Will try it first.

 

[ccolwell]

The down side or progressive springs (in general, not just Progressive) is they dive initially under braking using up the soft part of the spring, then stiffen up. To be sure, it's more of a problem when trail braking (I blame Reg Pridmore for my tendency to do that). I'd look at Race-Tech springs. I put them on my R90S and was very happy.

 

[gregfeeler]

You probably need stiffer springs. But if that were my bike I would add 15cc or so to the fork oil in each leg. That reduces the volume of the air above the oil. So the air compresses more as the forks compress. This air spring component can significantly reduce dive but have little effect on the reaction to small bumps, adding to rider comfort. Try it.

Another vote for Paul's suggestion. I was able to effect big improvements on my K75s with this method.

 

[twinmeister]

What Paul said....

I also have a 1986 R80. When new, I had Progressive springs added. Later added more preload and a bit more oil. Better, but not great. About six years later added Racetech cartridge emulators - much better!

 

[stevenrankin]

Race Tech

From what I have read about going to Race Tech cartridges, I myself can't justify the greater cost of installing them on my bikes. I am in the process of a major overhaul and now would be the time for me to do it as the forks are apart. The people whom I have asked about the RT system kind of hedge a bit on just how great they are. Looking at the cost from my standpoint, they better be fantastic, not just better or slightly better than the stock system or a set of progressive springs.

Mind you, I am the type of person who many years ago was enthusiastic about trying all the different tires hoping for the magic combo to give me great handling only to find I myself could not tell the difference between the go fast tires and the touring tires. What has happened is I now buy my tires for wear and price, another thread but the same thinking in my case applies here.

Not being familiar with RT's system, what if any is the big deal? OK, from looking at their website, I can assume they are adjustable for preload and so forth, Great, progressive springs can be adjusted as well by changing the length of the PVC spacer.
Are they adjustable for dampening? OKAY, that is a big plus, but I don't see that in the literature from the company.

So for me, I don't ride aggressively enough to justify the major cost of the RT system upgrade. Adding 10 or 15 mis of fluid or a piece of PVC is my way to go. Cheers, St.

 

[gregfeeler]

From what I have read about going to Race Tech cartridges, I myself can't justify the greater cost of installing them on my bikes. I am in the process of a major overhaul and now would be the time for me to do it as the forks are apart. The people whom I have asked about the RT system kind of hedge a bit on just how great they are. Looking at the cost from my standpoint, they better be fantastic, not just better or slightly better than the stock system or a set of progressive springs.

Mind you, I am the type of person who many years ago was enthusiastic about trying all the different tires hoping for the magic combo to give me great handling only to find I myself could not tell the difference between the go fast tires and the touring tires. What has happened is I now buy my tires for wear and price, another thread but the same thinking in my case applies here.

Not being familiar with RT's system, what if any is the big deal? OK, from looking at their website, I can assume they are adjustable for preload and so forth, Great, progressive springs can be adjusted as well by changing the length of the PVC spacer.
Are they adjustable for dampening? OKAY, that is a big plus, but I don't see that in the literature from the company.

So for me, I don't ride aggressively enough to justify the major cost of the RT system upgrade. Adding 10 or 15 mis of fluid or a piece of PVC is my way to go. Cheers, St.

Steven, I've studied the Race Tech cartridge emulators at length and in my opinion they are vastly superior to any of the conventional dampening rod forks found on all BMW bikes at least through to the end of production of the Airheads and Classic K-bikes in the middle '90's.

In the simplest of terms, dampening rod forks are not and can not be made velocity sensitive. They have fixed oil flow holes in the dampening rod, which are presumably optimized for someone's estimate of what will be the "normal" riding conditions for that bike. Within their design range for oil flow they can work well. However, their flow rate is determined by the orifice size (fixed) and the pressure of the fork oil (determined by the rate of movement of the forks - i.e. small bump vs. hitting a big bump as speed in combination with the fork oil viscosity). Under some combination of load, speed, and impact size, they can reach or exceed their flow range and then they approach hydraulic lockup and jar the crap out of you.

The RT cartridge emulators have three disks at each end of the emulator. One direction controls compression and the other rebound. These disks are large, medium, and small in diameter and work progressively like the leaf springs on the rear of a truck. The weakest disk allows low speed oil flow, and then when it reaches it's maximum flow rate, the next disk takes over, but requires even more pressure to open, and so on. By selecting different disks with different spring rates the forks can be tuned for just about any conditions, but at any point can accommodate a much wider range of oil flow velocity than any dampener rod design. The RT people are pretty good at what they do, and when you order for a given bike they have already specked the emulator you get for the best overall performance based on their experience.

Everyone I've talked to who has done this conversion has raved about it. However, I think it's important to note that Race Tech says you should also use their springs, their fork oil (they order in bulk and test viscosity and then re-label rather then trust the manufacture) and their method for determining the correct amount of oil to achieve the ideal air column in the forks. The people who have told me they did all those things have been the happy ones. I think in all cases if you don't follow the recipe you shouldn't be surprised with disappointing results.

 

[gregfeeler]

Steven, I've studied the Race Tech cartridge emulators at length and in my opinion they are vastly superior to any of the conventional dampening rod forks found on all BMW bikes at least through to the end of production of the Airheads and Classic K-bikes in the middle '90's.

In the simplest of terms, dampening rod forks are not and can not be made velocity sensitive. They have fixed oil flow holes in the dampening rod, which are presumably optimized for someone's estimate of what will be the "normal" riding conditions for that bike. Within their design range for oil flow they can work well. However, their flow rate is determined by the orifice size (fixed) and the pressure of the fork oil (determined by the rate of movement of the forks - i.e. small bump vs. hitting a big bump as speed in combination with the fork oil viscosity). Under some combination of load, speed, and impact size, they can reach or exceed their flow range and then they approach hydraulic lockup and jar the crap out of you.

The RT cartridge emulators have three disks at each end of the emulator. One direction controls compression and the other rebound. These disks are large, medium, and small in diameter and work progressively like the leaf springs on the rear of a truck. The weakest disk allows low speed oil flow, and then when it reaches it's maximum flow rate, the next disk takes over, but requires even more pressure to open, and so on. By selecting different disks with different spring rates the forks can be tuned for just about any conditions, but at any point can accommodate a much wider range of oil flow velocity than any dampener rod design. The RT people are pretty good at what they do, and when you order for a given bike they have already specked the emulator you get for the best overall performance based on their experience.

Everyone I've talked to who has done this conversion has raved about it. However, I think it's important to note that Race Tech says you should also use their springs, their fork oil (they order in bulk and test viscosity and then re-label rather then trust the manufacture) and their method for determining the correct amount of oil to achieve the ideal air column in the forks. The people who have told me they did all those things have been the happy ones. I think in all cases if you don't follow the recipe you shouldn't be surprised with disappointing results.

I should add that to upgrade to the RT cartridge emulators you drill out the dampening rod oil flow holes large enough (they tell you) to neutralize them. You still need the dampening rod to hold the fork together. The emulator is placed on top of the dampening rod and held in by the fork spring in a way that the fork oil has to flow through it.

 

[twinmeister]

I did not mean to sidetrack thread but let me add

I did use RaceTech oil and setup recommendations. A friend machined an adapter since RaceTech did not have exact size for fork inner dia. I actually have a little too much preload (with no spacer) and would prefer the shorter RaceTech springs.

 

[stevenrankin]

Jury is still out

Greg, did you install the system? Do you have a lot of miles on such a system and have you found the claims made by the company to be true? If you have installed the system, is it really so superior to a properly maintained OM system to justify the cost?

My most recent conversation with someone who installed the system was worded as he thought it was better planted than the OM system but it would take him longer to comment further on how it works.

To persuade me to drop the big bucks on the RT system I would expect someone who has installed the system to tell me how great it is not in extreme riding but average riding. I have read the brochures I see how it works on paper, great looking things don't always work as they should.

Anyway, this thread started out with one subject and perhaps I have diverted it to another. I stand by my first comment try Paul's advice, if that doesn't make a satisfactory change then the owner can go the other route of installing progressive spring or the RT system. It is his money he is spending and to be honest, I should stay out of it. St.

 

[gregfeeler]

Greg, did you install the system? Do you have a lot of miles on such a system and have you found the claims made by the company to be true? If you have installed the system, is it really so superior to a properly maintained OM system to justify the cost?

My most recent conversation with someone who installed the system was worded as he thought it was better planted than the OM system but it would take him longer to comment further on how it works.

To persuade me to drop the big bucks on the RT system I would expect someone who has installed the system to tell me how great it is not in extreme riding but average riding. I have read the brochures I see how it works on paper, great looking things don't always work as they should.

Anyway, this thread started out with one subject and perhaps I have diverted it to another. I stand by my first comment try Paul's advice, if that doesn't make a satisfactory change then the owner can go the other route of installing progressive spring or the RT system. It is his money he is spending and to be honest, I should stay out of it. St.

I have not installed the Race Tech kit, yet, but plan on doing so sometime by the end of next spring. Different people have different perceptions of suspension, tires, brakes, etc. I have one good friend who's criteria for tires is that they be round, black, and hold air. I've been known to pull of tires with lots of rubber left that didn't please me. So, to each their own.

 

[ccolwell]

FWIW, my experience installing emulators. https://forums.bmwmoa.org/showthread.php?42105-Gold-Valve-Emulator&highlight=gold+valve

 

[stevenrankin]

Coolwell

So, now you have these on your bike, can you honestly say they are worth the time and effort as well as money to install them? I mean, what was the final cost to install, I read your installation post, and I can well imagine my having the same problems and I am not a patient person so I am not amused by "improvement" projects that have the potential to irritate me. That aside, how about the cost? Dollar for dollar, do you still think it was worth it? And, finally not to be a jerk, but what condition were your forks in before you changed to the RT system? As I said to Greg, I am not saying you don't maintain your bikes, but, performance degrades over time with airhead forks, Are you in fact comparing now the new RT system with the old system while it was in good tune, ie, with fresh fork oil and good springs? For example, I myself am guilty of doing a tune up and suddenly the bike runs like new again and I am amazed I hadn't realized earlier the performance had dropped off noticeably. One of the things I try to do since getting burnt by this situation is to swap bikes with a friend or have my friend at his shop ride the bike. Sometimes they pick out things I have "gotten used to" and point them out.

So as it stands, I have one glowing report for RT, one mediocre with the caveat of extra time needed to try it out, and several other unknown quality positives, unknown because I am not aware of the condition of the bike before the change to give in my mind a fair comparison.

I will add, I upgraded my charging system to an Omega 600 Watt system, When done, I found a vast difference in output over the stock system and as I use a lot of power for electrical clothing, it was to me money well spent, and in fact I also upgraded my other bike.

I installed a Corbin seat after my stock seat wore, out, rather than buying another stock seat. This has turned out to be the biggest mistake I have made. Despite the hype from Corbin, to me their seats are no more comfortable than the stock seat. Add to that, they have the worst customer service. I must catch myself, this is not about Corbin, sorry, as you can guess, the money I spent on their product was not even close to being worth it.

I could go on and on regaling you with tales in my life of believing the hype from manufacturers that hooked me and then disappointed. Fool me once shame on me, fool me twice, ain't going to happen. I DO, appreciate the dialog on this topic because despite my negative attitude, I still have a feeling it might be time to try the RT system. Now with my bike apart for overhaul it makes the best sense of time to do it. Perhaps someone will nudge me in one direction or another, time will tell. Cheers, St.

 

[gator]

RT gets a 10+

I spent way to much money on different springs, different weight oils, and spacer lengths over the years. Can not even count the number of hours. I was never happy with any of the outcomes. I have had the RaceTechs on my /5 for 6+ years and love how they work and how easy it is to make changes. Do the whole thing don't cheap out because the oil is more expensive or believe that your Progressive wound springs will work just fine.
Best bang for the buck of any mod I have done to my /5 and I have done plenty of mods to mine.
Gator

So, now you have these on your bike, can you honestly say they are worth the time and effort as well as money to install them? I mean, what was the final cost to install, I read your installation post, and I can well imagine my having the same problems and I am not a patient person so I am not amused by "improvement" projects that have the potential to irritate me. That aside, how about the cost? Dollar for dollar, do you still think it was worth it? And, finally not to be a jerk, but what condition were your forks in before you changed to the RT system? As I said to Greg, I am not saying you don't maintain your bikes, but, performance degrades over time with airhead forks, Are you in fact comparing now the new RT system with the old system while it was in good tune, ie, with fresh fork oil and good springs? For example, I myself am guilty of doing a tune up and suddenly the bike runs like new again and I am amazed I hadn't realized earlier the performance had dropped off noticeably. One of the things I try to do since getting burnt by this situation is to swap bikes with a friend or have my friend at his shop ride the bike. Sometimes they pick out things I have "gotten used to" and point them out.

So as it stands, I have one glowing report for RT, one mediocre with the caveat of extra time needed to try it out, and several other unknown quality positives, unknown because I am not aware of the condition of the bike before the change to give in my mind a fair comparison.

I will add, I upgraded my charging system to an Omega 600 Watt system, When done, I found a vast difference in output over the stock system and as I use a lot of power for electrical clothing, it was to me money well spent, and in fact I also upgraded my other bike.

I installed a Corbin seat after my stock seat wore, out, rather than buying another stock seat. This has turned out to be the biggest mistake I have made. Despite the hype from Corbin, to me their seats are no more comfortable than the stock seat. Add to that, they have the worst customer service. I must catch myself, this is not about Corbin, sorry, as you can guess, the money I spent on their product was not even close to being worth it.

I could go on and on regaling you with tales in my life of believing the hype from manufacturers that hooked me and then disappointed. Fool me once shame on me, fool me twice, ain't going to happen. I DO, appreciate the dialog on this topic because despite my negative attitude, I still have a feeling it might be time to try the RT system. Now with my bike apart for overhaul it makes the best sense of time to do it. Perhaps someone will nudge me in one direction or another, time will tell. Cheers, St.

 

[stevenrankin]

Tipping

Ah, I am starting to tip in the RT direction, LOL.

Gator, after you installed the RT system, do you find you have kind of set it and forgotten it, or do you change settings regularly? One of the selling points of the RT system is easier adjustment, OK, I can see how that is achieved, but, once you got the system dialed in, have you used it since?

I had my stock system dialed in pretty darn good before this overhaul and it was working very well for my riding style. I may be tipping in the RT direction but I am not there yet, Has anyone changed over from the stock system on a 84 year bike in good working order to the RT system, and if so, was the conversion worth the money? Is there such an improvement to justify me going out and spending hundreds of extra dollars in this system?

I know, I am being pig headed, but it is my money, on bike maintenance and replacing parts, I don't skimp or go cheap. Performance stuff, is another story, I take any company's brochures with a grain of salt, sad to say, I have in the past on other things wasted money on performance upgrades.

You guys are the real deal, you along with the people I see at my friend's shop are the information I need to tap into to make for me a big buck change. Only by grilling you, and writing you, can I get to the kernel of truth regarding this change. I very much appreciate your patience and understanding in working with me. Hey after all, the more detail, dialog and follow up in threads, the more we learn from each other.

Bear with me, I am tilting. Who is going to knock me off the bench? LOL, Cheery bye St,.

 

[nickrides]

To counteract the front end diving; along with adding some more fork oil I'd increase the viscosity also. Thats cheap and easy and just might get you there.
Maybe go 2 levels up on the viscosity.
So easy to try.

 

[gator]

I had an 83T that I put RT fairing on only thing I have ever owned that would qualify as an RT. so most of my airhead experience has been naked bikes. I could never really get them Dialed in.
So if you really think your dialed in the money may not be worth it for you, however do you still get nose dive? does the riding over patches of poor asphalt make you crazy from the ripple bounce?
Those are the things I could never get right and the RaceTech system fixed all that.
Second question Last year I went to the next weaker spring as it was a bit harsh. After the dial in I don't mess with it anymore.
One thing of note if you look at oil Viscosity specs you will find a large amount of variation. In other words Viscosity is a measurement of how much oil will flow thru a certain fissure at a certain temperature. So your basic 15wt. oil may be close to 10 one time and close to 20 the next. All within Spec. RaceTech says this is what the spec is for our 15 and they don't really care that the 12 is "within spec" it is brought up to 15. This gives you much better control over what you are really doing. In my book if I were not using their parts I would still be using their oil. Seems expensive on the surface but control makes adjustment much easier. honestly dialed in how often do you change that pint of oil? If your happy with someone else's 15 that is really a 12 and change oil and it is closer to18, that is a pretty big jump and changes things alot.
Gator

Ah, I am starting to tip in the RT direction, LOL.

Gator, after you installed the RT system, do you find you have kind of set it and forgotten it, or do you change settings regularly? One of the selling points of the RT system is easier adjustment, OK, I can see how that is achieved, but, once you got the system dialed in, have you used it since?

I had my stock system dialed in pretty darn good before this overhaul and it was working very well for my riding style. I may be tipping in the RT direction but I am not there yet, Has anyone changed over from the stock system on a 84 year bike in good working order to the RT system, and if so, was the conversion worth the money? Is there such an improvement to justify me going out and spending hundreds of extra dollars in this system?

I know, I am being pig headed, but it is my money, on bike maintenance and replacing parts, I don't skimp or go cheap. Performance stuff, is another story, I take any company's brochures with a grain of salt, sad to say, I have in the past on other things wasted money on performance upgrades.

You guys are the real deal, you along with the people I see at my friend's shop are the information I need to tap into to make for me a big buck change. Only by grilling you, and writing you, can I get to the kernel of truth regarding this change. I very much appreciate your patience and understanding in working with me. Hey after all, the more detail, dialog and follow up in threads, the more we learn from each other.

Bear with me, I am tilting. Who is going to knock me off the bench? LOL, Cheery bye St,.

 

[stevenrankin]

Hey Gator

You have seen my point gator, I have my RT dialed in pretty well and really have not seen any bad problems with the stock system. Maybe it is just the fact I have gotten used to it and accept it for what it is? As for upgrading from a stock /5 or /6 suspension to race tech's system, I have never ridden one of those bike to know how they compare to my newer bike's suspension. I can imagine a change from 50's and 60's suspension technology to a more modern type would make a difference. I only have to look at the ride and handling differences between my bike an the new bikes.

Just for my information, I have sent a note to RT to see just what they say converting my bike to their system will cost. I am still on the fence. St.