Installing Hyperpro Springs Confusion - BMW G310 R/GS Forum
 1Likes
Reply
 
LinkBack Thread Tools
post #1 of 16 (permalink) Old 01-29-2019, 08:38 AM Thread Starter
Senior Member
 
Kris's Avatar
 
Join Date: Dec 2018
Location: India
Posts: 676
Installing Hyperpro Springs Confusion

Does anyone have experience with opening the left fork? I tried to install the hyperpro springs, and while it is all normal on the right side, I have no idea how to access the spring on the left. There is some strange contraption there that requires some special tool to open. I tried to do it without a oem tool, but that thing just does not want to move. I have opened many forks, and never have I seen such a thing! I would appreciate if someone has some knowledge here!
Kris is offline  
Sponsored Links
Advertisement
 
post #2 of 16 (permalink) Old 01-29-2019, 09:37 AM
Senior Member
 
Join Date: Oct 2016
Location: Montreal, Qc, Canada
Posts: 138
Have not done this. Did you check with Hyperpro for assistance ?
You can also consult the Rally Raid site for their document on their upgrade.
bbbelanger is offline  
post #3 of 16 (permalink) Old 01-29-2019, 09:54 AM Thread Starter
Senior Member
 
Kris's Avatar
 
Join Date: Dec 2018
Location: India
Posts: 676
Quote:
Originally Posted by bbbelanger View Post
Have not done this. Did you check with Hyperpro for assistance ?
You can also consult the Rally Raid site for their document on their upgrade.
I did install the Rally Raid rear shock, but in their front modification, the left shock is not touched, so they cannot assist with it. I will try tomorrow to improvises and open that thing. I think, I have little chance to get hold of the proper tool. I saw no mentions of that tool in google. It is called HP-T65
Kris is offline  
post #4 of 16 (permalink) Old 01-29-2019, 09:02 PM Thread Starter
Senior Member
 
Kris's Avatar
 
Join Date: Dec 2018
Location: India
Posts: 676
I found some info in this thread: https://www.g310rforum.com/forum/370...velopment.html

apparently, the inner cap in the left fork is hard-glued and one has to use a heat gun to open it. I will give it another try, even though I have to improvise, not having the proper tool.
Kris is offline  
post #5 of 16 (permalink) Old 01-30-2019, 08:09 AM Thread Starter
Senior Member
 
Kris's Avatar
 
Join Date: Dec 2018
Location: India
Posts: 676
so I have solved the problem. i used a 'special' tool, a leatherman pliers . First I heated the inner nut with the heat gun, and then with little force the nut unscrewed. can you believe that this nut is glued with red loktite? what are they thinking? sooner or later you need to change oil there; mine was already very dirty. in fact, it is always better to change the oil early, because all the parts are bedding in.

I noticed that there is a confusion in the forum as to what is inside the left leg. actually, there is the same spring as on the right side. there is just no damping.

I wonder how it works with RR kit. if the springs do not have the same length, the axle rod will not slide in smoothly. this what happened to me, when I fitted hypepro on the right side and left the stock one on the left (because I could not open the inner nut yesterday).

anyway, the front is now excellent, very stable and accommodating. no more front diving.

by the way, I filled both legs with nice synthetic 10W motul fork oil, viscosity 36.0. I personally would not go for higher viscosity.

Last edited by Kris; 01-30-2019 at 08:38 AM.
Kris is offline  
post #6 of 16 (permalink) Old 01-30-2019, 10:52 AM
JMo
Senior Member
 
JMo's Avatar
 
Join Date: Feb 2018
Posts: 237
Quote:
Originally Posted by Kris View Post
so I have solved the problem. i used a 'special' tool, a leatherman pliers . First I heated the inner nut with the heat gun, and then with little force the nut unscrewed. can you believe that this nut is glued with red loktite? what are they thinking? sooner or later you need to change oil there; mine was already very dirty. in fact, it is always better to change the oil early, because all the parts are bedding in.

I noticed that there is a confusion in the forum as to what is inside the left leg. actually, there is the same spring as on the right side. there is just no damping.

I wonder how it works with RR kit. if the springs do not have the same length, the axle rod will not slide in smoothly. this what happened to me, when I fitted hypepro on the right side and left the stock one on the left (because I could not open the inner nut yesterday).

anyway, the front is now excellent, very stable and accommodating. no more front diving.

by the way, I filled both legs with nice synthetic 10W motul fork oil, viscosity 36.0. I personally would not go for higher viscosity.

Hi Kris - if you are looking for an answer, I can tell you ;o)

The length of the spring does not dictate the travel, it is the length of the damper rod - and in both instances those remain unchanged (unless there is a manufacturer who is making a replacement cartridge kit for both legs).

As you ascertained, all the main 'functionality' is in the right hand leg of the G310 models - it's increasingly common practice for both cost and weight saving to split the damping and springing functions between legs - for example, the majority of dirt bikes have a compression [damping] cartridge in one leg, and the rebound cartridge in the other; while on budget bikes like the CRF250L for example, the spring is in one leg and the [combined] damping cartridge in the other - much like the majority of mountain-bikes these days too.

In the case of the G310 series, both the damping functions and main spring are in the right hand leg - the left leg has a simple rod (no actually damping control) and second 'helper' spring to match the travel length of the right hand leg - but all the primary function is in the right hand leg, which is probably why BMW used red Loctite to fix the components of the left hand leg together, as there is no need to split/change them, and the fork can be simply inverted to empty the oil as and when you need to change it (note. the oil in the left leg is primarily for lubrication, not damping, so it's weight and volume is not so specific as it is for the right hand side).

This is why (if you consult the Rally-Raid fork kit fitting instructions) you only need to change the spring in the right hand leg and set the oil lever [for the damping], and why their preload adjuster is only on the right hand leg.

You don't need to worry about forks being 'uneven' - particularly with USD forks - you could run them with nothing in the left if you wanted and it wouldn't affect the handling - the axle keeps everything parallel.

note. for info. the Rally Raid LEVEL 2 fork kit does not offer more overall travel (since the OEM damper rod remains unchanged), it simply moves the to of the damper rod down so that more chrome fork leg is showing/raises the front of the bike to match the extra travel and ride-height of the rear shock, but the actual swept length remains the same at the front - it is only the LEVEL 2 shock that offers more travel as well as an increase in ride-height.

Hope that clarifies things!

Jenny x
G0MYW likes this.
JMo is offline  
post #7 of 16 (permalink) Old 01-30-2019, 11:31 AM Thread Starter
Senior Member
 
Kris's Avatar
 
Join Date: Dec 2018
Location: India
Posts: 676
Quote:
Originally Posted by JMo View Post
Hi Kris - if you are looking for an answer, I can tell you ;o)

The length of the spring does not dictate the travel, it is the length of the damper rod - and in both instances those remain unchanged (unless there is a manufacturer who is making a replacement cartridge kit for both legs).

As you ascertained, all the main 'functionality' is in the right hand leg of the G310 models - it's increasingly common practice for both cost and weight saving to split the damping and springing functions between legs - for example, the majority of dirt bikes have a compression [damping] cartridge in one leg, and the rebound cartridge in the other; while on budget bikes like the CRF250L for example, the spring is in one leg and the [combined] damping cartridge in the other - much like the majority of mountain-bikes these days too.

In the case of the G310 series, both the damping functions and main spring are in the right hand leg - the left leg has a simple rod (no actually damping control) and second 'helper' spring to match the travel length of the right hand leg - but all the primary function is in the right hand leg, which is probably why BMW used red Loctite to fix the components of the left hand leg together, as there is no need to split/change them, and the fork can be simply inverted to empty the oil as and when you need to change it (note. the oil in the left leg is primarily for lubrication, not damping, so it's weight and volume is not so specific as it is for the right hand side).

This is why (if you consult the Rally-Raid fork kit fitting instructions) you only need to change the spring in the right hand leg and set the oil lever [for the damping], and why their preload adjuster is only on the right hand leg.

You don't need to worry about forks being 'uneven' - particularly with USD forks - you could run them with nothing in the left if you wanted and it wouldn't affect the handling - the axle keeps everything parallel.

note. for info. the Rally Raid LEVEL 2 fork kit does not offer more overall travel (since the OEM damper rod remains unchanged), it simply moves the to of the damper rod down so that more chrome fork leg is showing/raises the front of the bike to match the extra travel and ride-height of the rear shock, but the actual swept length remains the same at the front - it is only the LEVEL 2 shock that offers more travel as well as an increase in ride-height.

Hope that clarifies things!

Jenny x
Jenny, that's very interesting. But there is still a spring in the left fork, and the rate of that spring affects the front suspension as the whole, doesn't it? So why not to change that spring in conjunction with the right leg fork spring as well? When I fitted the hyperpro spring only on the right leg, the bike was still front diving, and with both springs it is not.

so you are saying that if the axle rod is not sliding properly due to the both fork extending in a different manner, it is not a problem, one can just force that rod anyway? doesn't it create some kind of stress on the axle?

I do have crf and because it was too soft, first i installed ohlins spring on the right fork, but since it was not enough, I fitted an additional spring in the empty left leg, from Race Tech, and it fixed the problem.

and one more thing - in which way these two systems differ - RR and hypepro? one just changing the right leg spring, and the other, the changing both?
Kris is offline  
post #8 of 16 (permalink) Old 01-30-2019, 12:16 PM
JMo
Senior Member
 
JMo's Avatar
 
Join Date: Feb 2018
Posts: 237
Quote:
Originally Posted by Kris View Post
Jenny, that's very interesting. But there is still a spring in the left fork, and the rate of that spring affects the front suspension as the whole, doesn't it? So why not to change that spring in conjunction with the right leg fork spring as well? When I fitted the hyperpro spring only on the right leg, the bike was still front diving, and with both springs it is not.

so you are saying that if the axle rod is not sliding properly due to the both fork extending in a different manner, it is not a problem, one can just force that rod anyway? doesn't it create some kind of stress on the axle?

I do have crf and because it was too soft, first i installed ohlins spring on the right fork, but since it was not enough, I fitted an additional spring in the empty left leg, from Race Tech, and it fixed the problem.

and one more thing - in which way these two systems differ - RR and hypepro? one just changing the right leg spring, and the other, the changing both?
Hi Kris - it depends on what you've changed the spring rate to - if the spring in the right hand leg is now stiffer than before (and stiffer than the one in the left leg), then the left leg spring isn't going to have any effect on the rate of the new [main] spring.

Traditional fork design (with a pair of springs) typically changes the rate of both springs [equally] as the load was shared between the two legs - but in modern USD designs, this isn't necessarily the case anymore (such as the CRF250L example I mentioned above, there is only one spring, in one leg only).

I don't know what spring rate Hyperpro are using in their kit, but it's possible [particularly if they are progressive rate] that the reason you felt your front end still diving with only one of their springs installed was because the initial rate was still very soft (and needed to be boosted by having their other spring installed) - as I say, the OEM left hand spring is really only there as a 'helper' for the main spring - so it's possible that Hyperpro have decided to share the spring load across two springs, rather than one (as per the OEM set-up and the RR upgraded parts), which is why yours still felt soft until you'd changed both springs.

There is nothing wrong with using their 'shared load' approach of course - however, as you experienced, it is very tricky for someone in their garage to disassemble the left hand internal assembly compared to the right hand side - something I presume Hyperpro didn't full consider perhaps?


As for your forks sliding at 'different rates', unless you have some kind of bushing or alignment issue, it should not make any difference - the forks tubes are designed to slide up and down with no discernible resistance, and the axle diameter of a USD fork braces the two lower [stanchion] parts anyway - this is one of the reasons why USD forks tend to have much larger diameter axles than older conventional forks used to have (which also sometimes had additional braces of course). As I say, there will be no discernible stress on the axle unless you are suffering stiction or an alignment issue with the fork legs/bushes.


Regarding your CRF front end - I can only imagine that the fork kit you initially fitted (in just one leg) did not have a sufficiently high enough spring rate for your intended application. I have a friend with a CRF250L rally with the Ohlins shock and fork kit, and that is very nicely dialled in - plush, but will little dive when you start to press on.


Your final question I hope I have answered already in my description above - basically the Rally-Raid fork kit replaces the OEM main spring with a stiffer rate spring - which essentially overrides any effect from the left hand OEM 'helper' spring, making the contents of the left leg essentially redundant with regard to the actual support and springing of the front end.

With the main spring rate now correct (ie not too soft as many people feel the OEM set-up is), you can dial in the sag correctly using the RR preload cap on that main spring, and set your oil weight [viscosity] and volume to suit your preference - for info. TracTive [who developed the front and rear suspension with Rally-Raid] felt that although still quite rudimentary, the OEM damping control was actually pretty good - certainly once their revised main spring was installed and the oil weight changed to match.


Certainly from my own perspective, I would have to agree - while I never covered many miles on an OEM set-up, the RR LEVEL 1 kit (that is standard travel and ride height) I have on my own bike feels very well composed over all surfaces. It's a pretty simple (and easy to fit) solution.

Hope that clarifies things a bit!

Jenny x
JMo is offline  
post #9 of 16 (permalink) Old 01-30-2019, 12:31 PM Thread Starter
Senior Member
 
Kris's Avatar
 
Join Date: Dec 2018
Location: India
Posts: 676
Quote:
Originally Posted by JMo View Post
Hi Kris - it depends on what you've changed the spring rate to - if the spring in the right hand leg is now stiffer than before (and stiffer than the one in the left leg), then the left leg spring isn't going to have any effect on the rate of the new [main] spring.

Traditional fork design (with a pair of springs) typically changes the rate of both springs [equally] as the load was shared between the two legs - but in modern USD designs, this isn't necessarily the case anymore (such as the CRF250L example I mentioned above, there is only one spring, in one leg only).

I don't know what spring rate Hyperpro are using in their kit, but it's possible [particularly if they are progressive rate] that the reason you felt your front end still diving with only one of their springs installed was because the initial rate was still very soft (and needed to be boosted by having their other spring installed) - as I say, the OEM left hand spring is really only there as a 'helper' for the main spring - so it's possible that Hyperpro have decided to share the spring load across two springs, rather than one (as per the OEM set-up and the RR upgraded parts), which is why yours still felt soft until you'd changed both springs.

There is nothing wrong with using their 'shared load' approach of course - however, as you experienced, it is very tricky for someone in their garage to disassemble the left hand internal assembly compared to the right hand side - something I presume Hyperpro didn't full consider perhaps?


As for your forks sliding at 'different rates', unless you have some kind of bushing or alignment issue, it should not make any difference - the forks tubes are designed to slide up and down with no discernible resistance, and the axle diameter of a USD fork braces the two lower [stanchion] parts anyway - this is one of the reasons why USD forks tend to have much larger diameter axles than older conventional forks used to have (which also sometimes had additional braces of course). As I say, there will be no discernible stress on the axle unless you are suffering stiction or an alignment issue with the fork legs/bushes.


Regarding your CRF front end - I can only imagine that the fork kit you initially fitted (in just one leg) did not have a sufficiently high enough spring rate for your intended application. I have a friend with a CRF250L rally with the Ohlins shock and fork kit, and that is very nicely dialled in - plush, but will little dive when you start to press on.


Your final question I hope I have answered already in my description above - basically the Rally-Raid fork kit replaces the OEM main spring with a stiffer rate spring - which essentially overrides any effect from the left hand OEM 'helper' spring, making the contents of the left leg essentially redundant with regard to the actual support and springing of the front end.

With the main spring rate now correct (ie not too soft as many people feel the OEM set-up is), you can dial in the sag correctly using the RR preload cap on that main spring, and set your oil weight [viscosity] and volume to suit your preference - for info. TracTive [who developed the front and rear suspension with Rally-Raid] felt that although still quite rudimentary, the OEM damping control was actually pretty good - certainly once their revised main spring was installed and the oil weight changed to match.


Certainly from my own perspective, I would have to agree - while I never covered many miles on an OEM set-up, the RR LEVEL 1 kit (that is standard travel and ride height) I have on my own bike feels very well composed over all surfaces. It's a pretty simple (and easy to fit) solution.

Hope that clarifies things a bit!

Jenny x
Jenny, thank you for that explanation! And yes, I was upset that Hyperpro did not include the left fork tool, and just left their customers in dark. From my past experience, they do not even agree to 'reveal' the viscosity of the fork oil the provide, other than vague description on the bottle '10W or 20W'. They just refuse to answer this question, hence I did not use their fork oil.

just to clarify. if both legs are fitted at the same hight on top, and yet the axle rod does not slide freely, this isn't a problem?

and one more question if you don't mind, which I asked in different thread - if the rear shock is stiffer than oem as the one provided in RR, shouldn't it change the equation in the chain adjustment?
Kris is offline  
post #10 of 16 (permalink) Old 01-30-2019, 12:53 PM
JMo
Senior Member
 
JMo's Avatar
 
Join Date: Feb 2018
Posts: 237
Quote:
Originally Posted by Kris View Post
Jenny, thank you for that explanation! And yes, I was upset that Hyperpro did not include the left fork tool, and just left their customers in dark. From my past experience, they do not even agree to 'reveal' the viscosity of the fork oil the provide, other than vague description on the bottle '10W or 20W'. They just refuse to answer this question, hence I did not use their fork oil.

just to clarify. if both legs are fitted at the same hight on top, and yet the axle rod does not slide freely, this isn't a problem?

and one more question if you don't mind, which I asked in different thread - if the rear shock is stiffer than oem as the one provided in RR, shouldn't it change the equation in the chain adjustment?
Hi Kris - ok, are you saying you've got both fork leg tops/caps at the same hight in the top triple-clamp, but you seem to be experiencing some kind of stiction through the fork stroke? If so, I imagine that is a bushing or alignment issue somewhere - are the fork legs straight and both triple clamps parallel for instance?

If the fork legs are a slightly different hight (I mean a couple of mm) it shouldn't make any difference until you reach the absolute limit of travel when the fork is fully extended - ie. the wheel off the ground, or fully compressed - then the 'stop' will be dictated where the shorter of the two damper rods is - eg. during full extension, the leg that is slightly higher in the triple clamp (more leg poking through the top of the triple) will dictate when the fork stops - even if the other leg has a few more mm to slide since it is lower in the triple - do you see what I mean?

Once the bike is floating on it's suspension somewhere between the two extremes, you shouldn't be able to notice it - so if you are experiencing some sort of stiction or binding, it is more likely worn bushes or fork/triple-clamp alignment.

note. be aware that when you do remove the front wheel, the two fork bottoms can appear to be misaligned when trying to slide the axle back through - this is likely due to the tolerances of the respective rods inside each fork (one being a damper rod, the other being essentially just a 'connector'), and certainly when John had the forks apart originally during the initial development, he noticed one rod was slightly longer (would extend further) than the other, which is why some bikes suffer with a top-out clunk noise under full extension, as one rod is reaching it's maximum extension before the other - essentially as I describe in the previous paragraphs.


I haven't seen the other question [thread] but essentially no - the stiffness of the rear spring has no baring on the chain adjustment setting since the amount of free play recommended at rest will have been based on when the swing arm is directly in line with the pivot and front sprocket (ie. maximum tension) and that wont change due to spring stiffness.

However, if you've fitted a longer travel shock [ie. LEVEL 2] - then the rest position (that is with the bike unloaded on the side stand when you'd be checking your chain tension) will have moved slightly - although in practice, it doesn't make any difference as the relatively short travel (and long swing-arm) on this bike means it's not moving through a huge arc anyway. If you're worried at all, alway err on a side of slightly looser rather than too tight when adjusting your chain.

Hope that helps!

Jenny x
JMo is offline  
Reply

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Similar Threads
Thread Thread Starter Forum Replies Last Post
HyperPro Shock Installed G310GS Lowered 2.5” klouseau BMW G310 GS General Discussion 21 08-23-2019 08:15 PM

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome