BP 51 Suspension Rebuild Process (3 Viewers)

[Aslantarek]

DISCLAIMER: i am incredibly frustrated and angry.. so what comes next is aggressive but informative

Ok so i have been all over the internet looking for information on this frankly piece of **** company's flagship suspension system and any information on it.. and for some reason everyone on every forum is talking about the same old things, either its the clunk or how hard it is to adjust..

Honestly this is frustrating because its an issue that has been discussed to death.. WE KNOW ... THEY ******* CLUNK.. AND ARE HARD TO ADJUST..

just to answer a quick question everyone might be thinking.. "why not return it tlike we all do and wait months for replacements?"
answer: Greatt question.. 1 i dont have the luxury to wait months for replacements.. 2 im in a country where i cannot for political reasons import or export anything and if i try to leave with them in a suitcase they will either be taxed with their full price or taken completely because yes that's the country i live in... and you might be tempted to ask " dont you have an ARB dealership " .. Yes!.. Yes we do.. but they are completely useless and cannot do anything including importing proper inventory to sell.. i have no idea why they are actually a dealership..anyway

Now on to the actually important stuff.. how to rebuild them and the very least what to adjust in nitrogen pressure..

I have taken mine apart and rebuilt them and i am here to tell you all the information i have gathered.. Now.. the BP51s are FULLY serviceable and actually every single part in it is replaceable. i have recently blown the oil seals that are located under the Comp and Reb adjusters.. and thank god i had an older shock that was broken i use for spare parts.. that i decided to practice taking apart everything in before getting to work on the one on the car.. i will put photos of the tear down process.. and btw ARB will not sell you the oil seal rebuild kit.. because god knows why.. so just a piece of info that they probably wouldn't want you to know.. take apart the oil seals and go to any store that sells hydraulic oil seals and match them.. they will work just fine.. they dont want anyone else to rebuild them because they probably run RnD on all shocks that come back to them.

My rear left shock burst in 4 places as far as i can tell.. both sides of the reservoir hose and the compression and rebound adjusters stack.. now getting to those seemed impossible and i found NOTHING online because somehow its a more guarded secret than the nuclear codes.. BUT i found it and took it apart.. here are some pics..

So you take apart the shock as you would any other 2.5 shock.. then.. using the adjuster spanner that comes with the kit.. you rotate the compression adjuster all the way down then keep going as it will start rotating on its self like a bottle cap until it comes completely off.. there are 2 oil seals that are 2mm thick on tthe top of it and one also 2 mm i think or 3mm in the middle of the compression adjuster once taken off..

Then it would look like in the picture.... so to take apart the part where it shows the compression and rebound levels.. youll need a T10 hex screw set.. you will take off 4 screws that come up with shimlike spacers (2 on each screw). that twill then reveal a second layer of screws, same deal just take them out but becareful with the orientation of everythting going in and out because they have to align with the bypass tubes in a certain way.. here is a picture of the screwed ...

After taking both rows off. the whole thing comes out with the rebound adjuster that has 4 2mm oil seals 2 on the top and 2 on the bottom and as far as i can tell nothing in the middle... also here are simple pictures to understand the allignment

The 4 holes on top allign with the large bypass tube

and the 8 holes in the bottom allign with the small bypass hole..

I will still be working on the top part of the shock and reservoir hose ends..



Quick conclusion .. Honestly with the crap information around for these amazing shocks and the secrecy with treating the information on it by ARB and their refusal to give you any parts to fix it if you are in a part of the world that cannot deal with them in anyway.. and the dealers are pretty much useless when it comes to then even fixing it themselves.. i have to say that while i love them when they work.. i wouldnt with them on my worst enemy, i will be looking into selling them come summertime and buying a proper suspension system where dealing with it isnt literal rocket science and where i dont have to solve the davinci code just get to a part of it..


P.S: this shock was broken thats why i took it completely apart.. and btw they are charged to 250 PSI nitrogen incase anyone wants to test theirs.. i really think they can go down to 200 but ofcourse i cant be sure because NO ONE IS TELLING ANYTHING... i read on one forum it was 300.. but when i got the new one and tested it, it was 250 so there you go.

 

[Erikytter]

I have also searched all over for rebuild information without sucess until i found this thread, have you continued the rebuild? Got any more info on the rest of the dissasembly? Or any info on the parts/whats leaking and how to fix it?

 

[Aslantarek]

I have also searched all over for rebuild information without sucess until i found this thread, have you continued the rebuild? Got any more info on the rest of the dissasembly? Or any info on the parts/whats leaking and how to fix it?

Hey, yea I finished it and everything works perfectly so let me know what you need and I’ll help anyway I can

 

[Erikytter]

Hey, yea I finished it and everything works perfectly so let me know what you need and I’ll help anyway I can

Perfect, did you pull apart and change gaskets at the reservoir hose? Did you find all gaskets at hydraulic stores or were there any gaskets you couldnt find?
Anything else that wasnt clear to take apart or buy parts for?

 

[Erikytter]

Perfect, did you pull apart and change gaskets at the reservoir hose? Did you find all gaskets at hydraulic stores or were there any gaskets you couldnt find?
Anything else that wasnt clear to take apart or buy parts for?

And did you need any special tools throughout the rebuild?

 

[Aslantarek]

And did you need any special tools throughout the rebuild?

Im not sure what you mean by gaskets.. but my hose was ripped in 2 but the end fittings both sides we fine so i went to a hydraulic factory and they were able to make me another hose that looked identical you couldnt tell the difference using the original fittings both sides.. same specs same length and i could have made it longer but i didnt for some reason.. would have been easier to fit the res somewhere safer.. but i dont think a hydraulic store would do cuz these need to be compressed to spec which only a factory can replicate
..
Honestly no special weird tools needed everything at the shop works

 

[sonji11]

Hey, yea I finished it and everything works perfectly so let me know what you need and I’ll help anyway I ca

Hey, yea I finished it and everything works perfectly so let me know what you need and I’ll help anyway I can

Hello mate! What fork oil and weight of oil did you use for your rebuild? And still 250 psi? Cheers!

 

[Aslantarek]

Hey I used Motorex 5W fork oil.. and yea right now I’m at 250 psi… got in contact with ARB and they said officially 290 plus or minus 15.. but anywhere down to 200 works but they recommend higher

 

[Lo2aY]

Not sure using hydraulic fluid is enough. The duty cycle on vehicle shocks is high compared to most machinery applications. Also the heat cycles will affect the fluid viscosity.

I would suggest contacting @cruiseroutfit. Kurt knows ARB more than anyone I know outside of ARB. If he can't sort it out, I'm not sure anyone else could.

It might be worth checking with him on this.

We resell ARB products here and we can't get an answer from our ARB reps in the middle east for repair kits. It's just crazy how the support is near non existing for the BP51s.

The shocks are great, when they work.

​

 

[sonji11]

Hey I used Motorex 5W fork oil.. and yea right now I’m at 250 psi… got in contact with ARB and they said officially 290 plus or minus 15.. but anywhere down to 200 works but they recommend higher

Thanks for the info mate! I just used motorex 7.5W. Should have used 5W instead, for sure would be better. I think for now, I need to compensate on my nitrogen pressure. Btw, when you get the psi per shock, is the shock loaded or unloaded with weight?

 

[Aslantarek]

Thanks for the info mate! I just used motorex 7.5W. Should have used 5W instead, for sure would be better. I think for now, I need to compensate on my nitrogen pressure. Btw, when you get the psi per shock, is the shock loaded or unloaded with weight?

It has to be unloaded.. so jack the car uptillthe shock is at full extension thats how you get a read and how you charge

 

[ChiChi]

Nice write up. Any other rebuild info you can send my way would be appreciated. Had my last flight with ARB, I’m done with them…..but the shocks are in good condition they just need a service.

 

[Aslantarek]

Nice write up. Any other rebuild info you can send my way would be appreciated. Had my last flight with ARB, I’m done with them…..but the shocks are in good condition they just need a service.

Well there is honestly and i just rebuilt a friends shock because of a broken bolt.. so tell me whats your issue and ill help you through it as much as i can

 

[ChiChi]

I was looking for any seals you used with part numbers. Parker’s hydraulic catalogue looks like they have everything I need, issue is I have to tear the shocks down and match the seals etc, trying to avoid to much down time. I was hoping that I could have some of consumables before I start the rebuild. Three of the shocks are leaking oil and nitrogen. I have gathered the Schrader valves and the stuff I need to replace the reservoir to shock body lines.

 

[Sandman614]

@Aslantarek thank you for your work! ARB told me

The serial numbers provided states that this suspension is the early production released BP51's.

The BP51 internal parts and reservoirs have been updated and unfortunately are not interchangeable with the early models. Therefore, new rear suspension would need to be purchased since the current rear BP51's on your vehicle are no longer rebuildable and have exceeded their serviceable life span.

My hose I suspect is leaking. I had taken them to a shop and they said no they'd give it a shot but no warranty because no OE parts were available. Well I get them back and the hose is still leaking after driving on the street, no offroad.. I'll take them to a hydraulic shop and see what they can do. Saving this thread before big secret shock manufacturer takes it down.

 

[Aslantarek]

@Aslantarek thank you for your work! ARB told me


My hose I suspect is leaking. I had taken them to a shop and they said no they'd give it a shot but no warranty because no OE parts were available. Well I get them back and the hose is still leaking after driving on the street, no offroad.. I'll take them to a hydraulic shop and see what they can do. Saving this thread before big secret shock manufacturer takes it down.

View attachment 3710225

hehe no surprises there.. ofcourse they would say that.. listen man there is no magic to it and there is no secret codes.. ARB is just really stupid when it comes to that stuff.. the hose does not have to be from ARB, it just has to be hydraulic. the hydraulic hoses are rated up to 350 BAR.. so it can EASILY handle a 300 psi suspension system.. just get proper insulated and pressure safe hosing and your good.. i actually once made hoses in a factory that are indistinguishable from the ARB one that the people at the authorized dealership couldnt tell the difference.. so theres that.. just make sure you dont bend the hose too much because they can break when bent if they are exactly like the ARB one... you dont need to buy new ones or anything.. just make sure all your seals are good and the pressure is good and you are good to go

 

[Sandman614]

hehe no surprises there.. ofcourse they would say that.. listen man there is no magic to it and there is no secret codes.. ARB is just really stupid when it comes to that stuff.. the hose does not have to be from ARB, it just has to be hydraulic. the hydraulic hoses are rated up to 350 BAR.. so it can EASILY handle a 300 psi suspension system.. just get proper insulated and pressure safe hosing and your good.. i actually once made hoses in a factory that are indistinguishable from the ARB one that the people at the authorized dealership couldnt tell the difference.. so theres that.. just make sure you dont bend the hose too much because they can break when bent if they are exactly like the ARB one... you dont need to buy new ones or anything.. just make sure all your seals are good and the pressure is good and you are good to go

Do you by chance know the thread and banjo size on the hose? I'll be taking mine off to measure but figure you might have beat me to it.

 

[Aslantarek]

Do you by chance know the thread and banjo size on the hose? I'll be taking mine off to measure but figure you might have beat me to it.

I redid it for me and a couple of people before but honestly I don’t remember the size.. I went to the hydraulic factory where they make them with everything and we fitted everything there so they can clamp the fitters and make sure everything is pressure tight…I recommend you do the same

 

[Sandman614]

I didn't see oil capacity measured, so here's what I could get out of my one that leaked(just over 12oz after getting the hose all the way off and cycling the shock more). These were "rebuilt" by a shop already so this isn't factory capacity.

And the fittings measure to be oring m10x1.0

 

[Sandman614]

While I wait on the hydraulic shop for my hoses, they said they'd have to special order the fittings..

The previous shop had a hell of a time getting these caps off and mangled the pin holes. Since they had them off, I figured this would be much less hard for me.. Or maybe they didn't actually get them off.