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HPP PRX Se pedal problem

Kek700

Premium
I have some HPP PRX pedals, I really wanted to see if all the positive reviews are justified about hydraulic pedals.
Unfortunatly mine have a lot of initial stiction, you could say a notch‘y start.
After that they are rather good, but every time I press them I have to go through a notch‘y start.
This is very annoying, it spoils their overall affect.
Has anyone got an answer, I have tried silicon spray, i just put it on the master and slave push shafts to some affect, soon back to that notch’y start.:mad:
 

stigs2cousin

Premium
It looks like there is a thread on the pushrod so you can adjust the freeplay between rod and piston.
Be carefull to leave a little gap so the piston can return to it´s endposition.

If there is no mechanical play ( gap) try to bleed the cylinders next.

MFG Carsten
 
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I am only a one day expert, as far as I can tell there is no bush, at least mine does not have one.
If the piston moves too far forward it will leak as shown in yours.
Easy job, remove master cylinder after disconnecting the pressure sensor from the electronics board, photo it first to see where they go.
Remove the four bolts from the slave cylinder, pull it apart including the piston with spring.
Now pull the master cylinder piston out with its spring.
Now check for scoring in both cylinders, should be none.
Though cleaning, then tip the unit so that the master cylinder is vertical after replacing the slave cylinder piston and spring with the four Allen bolts, making sure to lubricate the bore with a low viscosity oil, I used 0W40 mobile1.
This is what you are going to use, not brake fluid.
Open the bleed nipple, removed mine, fill the master cylinder with oil.
It will virtually bleed itself, tighten the bleed nipple.
Push the master cylinder in release the bleed nipple slightly and with the piston push the fluid through making sure all the air has expelled.
Tighten the bleed screw.
The master cylinder piston should be about flush with the master cylinder housing, bolt it back and you are good to go.
If your bores are scored, the above is of no use, you can buy honing stone for this bore diameter from eBay.
Then apply the above.
I have short cut the description because it will all become apparent as you go.
Took me about an easy hour to do the above.
May i ask why we use motor oil and not brake fluid other than brake fluid being nasty to work with?
 
Upvote 0
I am only a one day expert, as far as I can tell there is no bush, at least mine does not have one.
If the piston moves too far forward it will leak as shown in yours.
Easy job, remove master cylinder after disconnecting the pressure sensor from the electronics board, photo it first to see where they go.
Remove the four bolts from the slave cylinder, pull it apart including the piston with spring.
Now pull the master cylinder piston out with its spring.
Now check for scoring in both cylinders, should be none.
Though cleaning, then tip the unit so that the master cylinder is vertical after replacing the slave cylinder piston and spring with the four Allen bolts, making sure to lubricate the bore with a low viscosity oil, I used 0W40 mobile1.
This is what you are going to use, not brake fluid.
Open the bleed nipple, removed mine, fill the master cylinder with oil.
It will virtually bleed itself, tighten the bleed nipple.
Push the master cylinder in release the bleed nipple slightly and with the piston push the fluid through making sure all the air has expelled.
Tighten the bleed screw.
The master cylinder piston should be about flush with the master cylinder housing, bolt it back and you are good to go.
If your bores are scored, the above is of no use, you can buy honing stone for this bore diameter from eBay.
Then apply the above.
I have short cut the description because it will all become apparent as you go.
Took me about an easy hour to do the above.
I did the bleed procedure like u said and it solved my issues.
Thank you again.

While we are on the topic of these pedals.
If anyone has the clutch pedal for these PRX Se pedals and is willing to sell it separately please message me. I'd be very interested as I would like to make the 2 pedal kit I bought a complete set
 
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Here is the issue I'm having. Sorry for the **** quality of video.

There is a substantial amount of movement in the pedal before the hydraulics engage the slave cylinder to pull the rod of the slave cylinder.


Yes this is exactly what mine are doing (not as severe yet). A notable about of free play before it engages. So bleeding in the fix?
 
Upvote 0

Kek700

Premium
@Jrehm

At first I used brake fluid, but it had a lot of initial stiction that you had to overcome + HPP recommend thin oil.
I chose 0W40 because it was available, after bleeding with this 0W40 oil most of the stiction was gone + it is nowhere as nasty if it leaks and working with motor oil is better.
There are fluids that are specifically made for hydraulic system that try and remove slip stick, ie stiction. In fact I think they use a rotating seal in an attempt to remove this problem In hydraulic systems were this is a problem.
But in the end I was reasonably happy with the motor oil.
I may if the mood takes me buy some, I think it is called Renolin hydraulic fluid, the initial stiction is irritating. :(
 
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Yes this is exactly what mine are doing (not as severe yet). A notable about of free play before it engages. So bleeding in the fix?
i dont think it fixed it 100%but it did help.
i contacted mark at HPP to get his thoughts so hopefully i will get a reply back shortly
 
Upvote 0
Can someone do me a Favour if possible.
Can they take a photo of the plug connection for the brake pedal to the circuit board. Which wires go where.
i took a picture before disassembly but some how i accidently deleted it i think.
Throttle pedal works and will calibrate in IRacing, But the brake wont do anything.
I placed the red wire on the 5V pin,
Black on Ground
And white on the Signal pin.
 
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Kek700

Premium
[
9B837793-0BB4-42E5-A3AF-C6C875A662A0.jpeg


The brake is the first one , top.
 
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Kek700

Premium
As long as the bores are good and the seals are good, you should have no problem with bleeding them.
I have bought seals from Germany, waiting for them to turn up,
but will use them as spares, my bores were in perfect Condition.
The bleeding process will very easily remove all the air, you need the master cylinder to be vertical
just pour the oil in allowing it to flow out of the bleed nipple, I removed mine,, then replacing ithe bleed nipple when all air is expelled, just a couple of seconds should do it.
Then fill the master cylinder to the top, break open slightly the bleed nipple this time when putting the piston into the master cylinder with its spring, a jet of oil will fly out of the reservoir hole, then keep pushing the piston with the bleed nipple slightly cracked open until the piston is level with the master cylinder body, tighten the bleed nip,e.
Took 10 times longer to explain than it does to do it.
Done this many times, when experimenting, it is fool proof.
if you are having problems then I would suspect bores or seal, both are easy to diagnose visual,y.
 
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Wierd that ur brake is starting on the 2nd row and u have nothing on the first row.
I didn't disconnect the throttle and never had an issue with it..
 
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Kek700

Premium
You can put it anywhere, there are a lot of vacant spaces not used.
It just happened that was how mine was connected, remember I have a clutch.
 
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Kek700

Premium
A video of the bleeding process would be a huge help if anyone is up for it please.

It is really easy, if I did not have to strip it and mess from the oil was not a problem, I could do it in 5 minutes.

It is nothing like bleeding a cars braking system.

It virtually bleeds itself
 
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Kek700

Premium
Just one note to cover my back, if you are being very specific and really want every drop of air out of it.

Then you can easily manipulate the master and slave cylinder to ensure every drop of air is gone.
I have bleed it 5 times as described, without any problems.
 
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Anyone know if it's possible to purchase a new pressure sensor from?
i've narrowed it down to either the wiring in the sensor or the sensor it's self being the reason why i cant calibrate the brake in IRacing.
i dont have a multimeter at home to test it tho, so i might have to wait till tuesday to get my multimeter from work to properly test it
 
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Kek700

Premium
I wonder if the tunnel to the sensor that is blocked, knowing how much gunge was coming from your pedals.
I am of the opinion that your sensor is probably ok.
Have you removed it to see if it is blocked. :)
 
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i havent removed the sensor yet just because i dont want to un-bolt them from the rig and bleed the system again lol. it is very possible though to be honest
 
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Kek700

Premium
My last comment on this ( i have bleated on enough :roflmao: ), you should really from looking at your photos, strip, check, clean and bleed them.
otherwise you are storing up problems for the future, you never know, if you leave them you may be doing damage to the irreplaceable cylinders.:unsure:
 
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