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Bluto Tuning Thread

187K views 699 replies 165 participants last post by  nstelemark 
#1 ·
I know this is a more limited group, but for any/ all Bluto adopters, where are you running your fork? I am having to drop my pressure way below recommended to get any good action out of the fork and get full travel. Even at 75psi, I get 15% sag and the fork feels super stiction-ey. Dropped it down to 65 to try later today. I'm 165- 170 all kitted up, so should be 100+ psi.
 
#478 ·
friend of mine would like to upgrade his bluto to RCT3 damper. he just needs to purchase the 'pike' RCT3 damper right? no other parts needed? has it been determined what the correct oil volume is? And a related question -- I've seen a post saying 'factory bluto RCT3' but SRAM's website still only shows the RL version....?
 
#480 ·
I did a quick 9 mile ride this morning before work. !st ride out with my new 120 Bluto on the Fatboy. After going through this thread a few times I decided on adding two pucks and starting out at 90 PSI. I'm probably about180 geared up. I also dropped the stem one spacer from the factory setup. Here are my initial thoughts.

- I had no issue what so ever with a light front end on steep climbs
- Steering response is a slight bit lazy compared to the stock ridged setup but not a problem at all
- I ran 10 PSI up front compared to around 6 or 7 rigid so pretty much all of the self steer was gone.
- Small bump compliance was good, didn't bottom out but also didn't have any bigger hits. I'm going to play with pressure slightly
- Didn't even check the factory rebound setting and it seemed very good.
- No stiction issue at all
- Realized I can motor through the rock gardens pretty fast with the fork so I now need to up the rear tire pressure a bit to protect the rim

I'm pretty much a set and forget kind of rider. Reading this thread seems to have helped me find the setting I need for the terrain I ride and my riding style. I'll play with pressure slightly but it felt so good I may realize my starting pressure is where I need to be.

As I read this fork completely transforms this bike. If you're on the fence as I was, don't wait any longer to do this upgrade. Each day you wait is another day you'll miss out on all the benefits of this fork. Merlin Cycles is selling the 120 Bluto right now for $386 shipped. That's what put me over the edge. Thanks Merlin!!
 
#481 ·
Help - my bluto is sticky. :(

It appears to be sticking on the bushing. It was sticky so I rebuilt the fork thinking maybe the foam rings needed more lube (they did), but when I put the lowers back on, i noticed that it still sticks quite a bit even before the push rods for the air spring or the compression/rebound damper are even engaged. There are two bushings in each leg that make contact with the upper legs. I was concerned that maybe I didn't properly lube these, so I took the fork apart again. I visually inspected the inside of the lowers and didn't see anything that would make me concerned, and I saw oil from the open bath had coated the inside of the legs including the bushings.

I looked at the uppers and they look ok, too. However could they be bent? or could my bushings be damaged? or and I just missing something obvious. (i am really hoping I am just a dumass, and somebody will say - do this and it will be butter smooth.)

Thoughts?
 
#482 ·
Help - my bluto is sticky. :(

It appears to be sticking on the bushing. It was sticky so I rebuilt the fork thinking maybe the foam rings needed more lube (they did), but when I put the lowers back on, i noticed that it still sticks quite a bit even before the push rods for the air spring or the compression/rebound damper are even engaged. There are two bushings in each leg that make contact with the upper legs. I was concerned that maybe I didn't properly lube these, so I took the fork apart again. I visually inspected the inside of the lowers and didn't see anything that would make me concerned, and I saw oil from the open bath had coated the inside of the legs including the bushings.

I looked at the uppers and they look ok, too. However could they be bent? or could my bushings be damaged? or and I just missing something obvious. (i am really hoping I am just a dumass, and somebody will say - do this and it will be butter smooth.)

Thoughts?
Did you notice if the inside of dust seals had grease? If they were dry and you didn't re-grease them I could see that being source of stiction. I use slick honey on the seals when servicing the lowers.
 
#484 ·
@ kwarwick - I did grease the seals. I was out of slick honey, so I used so lithium grease I had available. I plan to rebuild before the season with the ETR kit, so I wasn't too concerned as I only used the lithium grease on the seals. Maybe that's it, but I wouldn't think so as it seems really stiff when I first engage the lower bushing with the uppers when reassembling the fork. Prior to that when the wipers are fully wrapped around the uppers, it moves smoothly.

The reason I was taking the fork apart because it hadn't been performing well. I had determined that the first thing I needed to address was the fact that I had air trapped in the lower. I determined that because when I let all of the air out and I still had a fully extended fork that would rebound.

@bdundee. I rode on it from last november. 3-4 hours/week in the winter. Less starting in May. So maybe 75 hours? I rebuilt it once in February because it was very sluggish in cold weather. I didn't do the ETR, but I rebuilt with slick honey. That helped.

It's working much better after the recent rebuild. I got the trapped air out and I made sure I had 5 ml of oil in each leg. I used RS 15 wt. But its not supper smooth. I still get a bunch of stiction compared to my reba xx. I don't expect it to be xx calibur, but really the difference should be in damper. I know the reba is dual air, and the bluto is solo - so the springs are not the same, but I wouldn't expect a solo air to be sticky.

I may just have to rebuild again with the ETR kit and make sure I SRAM butter the heck out of everything.
 
#485 ·
@ kwarwick - I did grease the seals. I was out of slick honey, so I used so lithium grease I had available. I plan to rebuild before the season with the ETR kit, so I wasn't too concerned as I only used the lithium grease on the seals. Maybe that's it, but I wouldn't think so as it seems really stiff when I first engage the lower bushing with the uppers when reassembling the fork. Prior to that when the wipers are fully wrapped around the uppers, it moves smoothly.

The reason I was taking the fork apart because it hadn't been performing well. I had determined that the first thing I needed to address was the fact that I had air trapped in the lower. I determined that because when I let all of the air out and I still had a fully extended fork that would rebound.

@bdundee. I rode on it from last november. 3-4 hours/week in the winter. Less starting in May. So maybe 75 hours? I rebuilt it once in February because it was very sluggish in cold weather. I didn't do the ETR, but I rebuilt with slick honey. That helped.

It's working much better after the recent rebuild. I got the trapped air out and I made sure I had 5 ml of oil in each leg. I used RS 15 wt. But its not supper smooth. I still get a bunch of stiction compared to my reba xx. I don't expect it to be xx calibur, but really the difference should be in damper. I know the reba is dual air, and the bluto is solo - so the springs are not the same, but I wouldn't expect a solo air to be sticky.

I may just have to rebuild again with the ETR kit and make sure I SRAM butter the heck out of everything.
Hmmmm... tough call. I know my first Bluto RL seemed pretty sticky too... never took it apart to figure out why as I ended up replacing it with a newer RCT3 model. The RCT3 seems better, but still not as smooth as my other RCT3 forks (Revelation, SID).

I think that some of the perceived stiction might be due to the tires on a fat bike, having so much more air volume and less pressure, tend to compress a lot before the shock is forced to move. This inertia makes it seems like the fork is stickier.... just a theory.
 
#486 ·
Have any of you had issues with the QR? I have a Salsa Hub with QR and noticed today when I would rotate the QR to release the axle, nothing happens, it just spins (QR)
Funny thing is the fork was just brought in for a tune up to my LBS and now I'm having issues with the QR. Talk about BS!!
Besides taken it back to the LBS, what else can I do to release the axle?
 
#493 ·
OK, I've had 2 Blutos now and had the same issue on both, they both worked fine at first, but then after a VERY short time air apparently migrated into either the neg air chamber or the lowers, causing the fork to stick a little when first compressed but then drop to about 1/2 travel with NO real increase in linear force application.

From what I'm reading flipping through this thread, it's that RS just messed up and undersized the O-rings? Not riding in the cold, just 70 and sunny in San Diego. Love the Bluto when it's working fine but honestly RS should have recalled these POS's.... aside from this issue the fork performs fine. Bought the one fork as OEM from Bikesdirect.com so I'm a little leery of the PITA it will probably be to have my LBS warranty it for me- I'd rather just fix it myself- especially since I bought the 2nd fork used. Should the Turnagin Orings solve the issue? Thanks!
 
#494 ·
Both my brother and myself have the Bluto 100mm both pumped up to 120psi. On mine the sag is about 17% but when I push down hard on the bars I can get the red ring to go to the top, but when I get on my brothers bike sag is around 30% and I can't get the red ring to move to the top.
Any ideas why 2 Bluto's set up the same would be performing so differently?
 
#497 ·
Paying $55 for three o-rings, two crush-washers and some lube - makes me wonder what exactly I'm supposed to be using the lube for.

I suspect all they did was spec alternative material o-rings (viton VS buna) or something similar.

Turnagin - sorry, but @ $55, I'm not going to be using your lube.
 
#498 ·
So is there a solution to the air leaking into the lowers or is it just something we all have to live with? Tried to find a RS parts list from 2014 to see if there was any difference between the original o-ring P/Ns and the ones in the 2015-2016 Parts list- but couldn't find a prior year Parts list.
 
#504 ·
I will investigate that, but I kinda doubt that's what I have going on. I'm assuming the hole you are referring to it the transfer port between +and- spring chambers?
Even if that is the case the seal head shouldn't be dumping air into the lowers.

Sent from my SAMSUNG-SM-N910A using Tapatalk
 
#508 ·
So what happens if you remove or add tokens to the bluto? My 80 mm has two tokens stock. I have a new 100mm air sleeve and a bag of tokens ready to install. Not sure of which way to go more or less tokens.

Thanks,

urmb
Basically they make the fork more progressive to so it doesn't bottom out on bigger hits yet able to run a lower psi to help in small bump compliance. There is no set number on how many to use it is more rider specific for what you weigh, how you ride, and how you want your fork to perform.

Here's what I do starting with no tokens. Set the sag in whatever rider position you want, beat the crap out of it, and if you don't use all the travel or close to it release a little air and repeat. If it bottoms out to easy add a little air, if feels to harsh after adding air go lower psi and add a token or two and beat the crap out of it again and check travel and feel
 
#515 ·
I'm pretty sure you need to replace the entire compression lock mechanism to the remote lock version. You can't just convert the knob. It should be easy, but it isn't cheap. Last time I poked around they were going for $80-100. Did a quick eBay search and don't see any for sale, might need to get your lbs to order.
 
#517 ·
I was just searching around for a 100 mm air shaft to reduce travel from 120mm for winter riding. Apparently, air shafts are now available in 80mm, 90mm, 100mm, 110mm, and 120mm, so now you can really fine tune your travel preference. Treefort bikes had all the different sizes listed.
 
#518 ·
120mm Bluto stiction solved!

I have a 120mm Bluto RL on my Foes Mutz and have been underwhelmed with its performance to say the least. It has always had a ton of stiction on initial movement along with inconsistent damping and bottoming. My first rebuild included switching to Slick Honey grease and 7wt oil set at highest level and no Tolkens. It was a big improvement but I had noticed something odd while I had it apart. The damper shaft has a groove around it at the top where it is clamped to the valve body, this is what holds them together, nothing strange here until I realized that when the shaft is fully extended (topped out) the inner o-ring on the white plastic seal assembly sits in this groove and causes the initial stiction. You can feel it just by sliding the seal up and down, its nice and smooth until it reaches the top and the inner o-ring seats in the groove and makes it harder to slide back down.
I recently bottomed my fork pretty hard on a 4' drop off and it never felt the same so time for another rebuild. This time I decided to address the o-ring issue so I installed another small o-ring at the top of the shaft to keep the seal from traveling up far enough for the inner ring to fall into the groove. Problem solved, the fork is so much more responsive and smooth. I know this only has an effect on bumps after the fork has fully extended but to me its noticeable throughout the ride not to mention it was almost impossible to set the sag properly. Now the fork moves with the slightest pressure on the bars and settles into 20% sag nicely. I also used 10wt oil set to 70mm height, no air spacers and I get full travel with no wallowing or diving like it was originally.
I assume this isn't a problem with shorter travel settings since the seal wouldn't come close to the groove.
 

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#576 ·
I have a 120mm Bluto RL on my Foes Mutz and have been underwhelmed with its performance to say the least. It has always had a ton of stiction on initial movement along with inconsistent damping and bottoming. My first rebuild included switching to Slick Honey grease and 7wt oil set at highest level and no Tolkens. It was a big improvement but I had noticed something odd while I had it apart. The damper shaft has a groove around it at the top where it is clamped to the valve body, this is what holds them together, nothing strange here until I realized that when the shaft is fully extended (topped out) the inner o-ring on the white plastic seal assembly sits in this groove and causes the initial stiction. You can feel it just by sliding the seal up and down, its nice and smooth until it reaches the top and the inner o-ring seats in the groove and makes it harder to slide back down.
I recently bottomed my fork pretty hard on a 4' drop off and it never felt the same so time for another rebuild. This time I decided to address the o-ring issue so I installed another small o-ring at the top of the shaft to keep the seal from traveling up far enough for the inner ring to fall into the groove. Problem solved, the fork is so much more responsive and smooth. I know this only has an effect on bumps after the fork has fully extended but to me its noticeable throughout the ride not to mention it was almost impossible to set the sag properly. Now the fork moves with the slightest pressure on the bars and settles into 20% sag nicely. I also used 10wt oil set to 70mm height, no air spacers and I get full travel with no wallowing or diving like it was originally.
I assume this isn't a problem with shorter travel settings since the seal wouldn't come close to the groove.
Hmmmm, are you sure this wouldn't be an issue on a 100mm fork? I seem to be having the same issues; stiction and sag is only a few mm with low air pressure for my weight. Assuming my pressure gauge is accurate anyway.
I think it's time for a rebuild anyway so I think I'll try the extra o-ring and see if it works. Couldn't hurt anything.
 
#519 ·
The top pic shows the additional o-ring I installed, you can see the groove above it that interferes with the inner o-ring of the seal. I the pushed it past the groove so it rests against the spacer. Now the seal doesn't travel up far enough for the inner o-ring to fall into the groove.
For suspension fork newbies, the chrome shaft is attached to the lower fork leg and moves up and down with the lower legs and wheel, the white seal sits at the bottom of the inner leg and keeps the oil from draining into the lower leg. The piston at the end of the shaft is what does the actual damping as it moves through the oil
It actually feels like a normal fork now. At first I thought it was designed like this for a reason but I cant imagine why. Its so much better this way
 
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