ooooooooooo

Odd Problem - Brakes Soft After Climbing Incline

th797

New member
Joined
Aug 18, 2021
Messages
19
Points
3
Location
Sault Ste. Marie, ON, Canada
Roxor Ownership
Roxor Owner
Hi all,

I've had my 2018 Roxor for about 1 year and it has ~1,000 miles / 125 hours. I have a consistent problem that occurs when I climb an incline and it's immediately after on the next stop my brake pedal nearly goes to the floor as if there's air in the system. It took me some time to notice as I didn't drive it in the winter. The master cylinder reservoir is topped up and the brakes work perfectly in normal driving. I have searched and haven't seen anyone encounter similar issues. Any ideas are welcome.

Thank you in advance.
 

44Bogger

Member
Joined
Oct 2, 2018
Messages
64
Points
18
Location
DeRidder, LA, USA
Roxor Ownership
Roxor Owner
I
Hi all,

I've had my 2018 Roxor for about 1 year and it has ~1,000 miles / 125 hours. I have a consistent problem that occurs when I climb an incline and it's immediately after on the next stop my brake pedal nearly goes to the floor as if there's air in the system. It took me some time to notice as I didn't drive it in the winter. The master cylinder reservoir is topped up and the brakes work perfectly in normal driving. I have searched and haven't seen anyone encounter similar issues. Any ideas are welcome.

Thank you in advance.
I have had the same issue crossing ditches. Make it to the other side and zero brakes.
but they come right back after leveling off. That’s about all the incline we get in south Louisiana.
 

th797

New member
Joined
Aug 18, 2021
Messages
19
Points
3
Location
Sault Ste. Marie, ON, Canada
Roxor Ownership
Roxor Owner
I

I have had the same issue crossing ditches. Make it to the other side and zero brakes.
but they come right back after leveling off. That’s about all the incline we get in south Louisiana.
Very interesting - sounds like the exact same issue. Hopefully we can figure it out.
 

MikeT

Active member
Joined
Jan 27, 2019
Messages
117
Points
28
Location
Montpelier, VT, USA
Roxor Ownership
Roxor Owner
Two things would cause this. Air in the line or a master cylinder problem. If you are not losing fluid there probably isnt a hole in the brake lines, but there could be some air in there. Bleed the brakes as its inexpensive.
Look at the master cylinder to see if fluid is on it.. again you said its full so probably not. The roxor mc is vacuum assist so check the air hose leading to it for cracks or loose fittings. Look at the mc assembly also to see if there is a leak in the housing. Im thinking the shift in components due to the incline or bounce opens an air leak.
its possible but doubtful that the mc itself has an internal leak.
 

Dan H.

Active member
Lifetime Member
Joined
Jan 5, 2021
Messages
129
Points
43
Location
Yuba CIty Ca.
Roxor Ownership
Roxor Owner
Roxor #
2019
Could the master cylinder be at a bad angle allowing air to enter somewhere when on a incline?
 

MikeT

Active member
Joined
Jan 27, 2019
Messages
117
Points
28
Location
Montpelier, VT, USA
Roxor Ownership
Roxor Owner
Doubtful in this case only because it would have to replace fluid with air. The master cylinder is full according to TH and no signs of leakage.
A possibility is the air line to the mc is partially obstructed or losing integrity ( going from round to flat) under an incline load.
 

1BB

Member
Joined
Nov 9, 2019
Messages
47
Points
18
Location
Church Point, LA, USA
Roxor Ownership
Looking to buy
Hi all,

I've had my 2018 Roxor for about 1 year and it has ~1,000 miles / 125 hours. I have a consistent problem that occurs when I climb an incline and it's immediately after on the next stop my brake pedal nearly goes to the floor as if there's air in the system. It took me some time to notice as I didn't drive it in the winter. The master cylinder reservoir is topped up and the brakes work perfectly in normal driving. I have searched and haven't seen anyone encounter similar issues. Any ideas are welcome.

Thank you in advance.
Have you figured out what's wrong yet?

How steep are the hills you're climbing when this happens?

And it ONLY happens after negotiating a hill, correct?

What I'm thinking is, if the master cylinder is sitting at an angle already when the vehicle is on the level, and the hill you climb exaggerates that angle, you could be having a small amount of brake fluid leaking past your pistons and back into the MC reservoir, and now when you apply your brakes, the fluid in your primary or secondary circuit under the MC reservoir may not be there, and your pedal will go down a lot further than normal.

All MC's have a 60/40 braking ratio. You have 60% on your front wheels and 40% on your rear wheels.

Your front brakes are being applied before your rear brakes so you can maintain steering.

Once you step on your brakes, the primary piston creates hydraulic pressure to apply your front brakes, AND also create hydraulic pressure to be applied against your secondary piston for your rear brakes. Once your rear brakes start to be applied, the pedal gets hard. Thus you have your 60/40 braking ratio in a working system.


Okay, if the front or primary brake hydraulic system fails to build up pressure, you have a steel rod that will EVENTUALLY make connect with the secondary piston and now the mechanical connection starts to push and create hydraulic pressure for your rear brakes.....and the pedal has to go a loooong way before for this to happen.

If your front brakes are working and building up hydraulic pressure, but your rear or secondary circuit has failed, again the pedal will go all the way down until it hits its mechanical stop, and it can build up full hydraulic pressure for your front brakes to be completely applied, but again the pedal has to go a loooong way before this happens.


Now when you release the brake pedal, it comes back to its resting position, BUT it also sucks brake fluid back into those primary and secondary circuits and refills them from the reservoir, and everything is good to go again, and you have normal braking....until the next steep hill.

In any case this is not normal at all, and it "COULD" indicate your MC "COULD" be having leaking issues, and "COULD" fail if the brakes are slammed in an emergency stop.

Next time you go up a steep hill, when you get to the top, apply your brakes rather HARD, not slam them but as you would if you had to make a very quick stop, and see if the pedal goes to the floor again, BUT also see if your front end dips. If it does, your front brake circuit is working, but if it does NOT dip, and you go to the floor and still slow down, your rear brakes are working. All you're doing is trying to figure out which braking circuit could have a possible bleed back issue and do further inspecting and troubleshooting. I would also turn around and go down the same hill and see if it happens again.

It's one thing if you can't start and you can't go, but it's another thing when you can't stop or you can't steer. Both systems have mechanic backups in case of hydraulic failures, and brakes have three really since it has TWO separate hydraulic braking circuits, and a hand brake or emergency brake, but still, it's scary and the ole pucker factor is running a 110% and you couldn't pound a pin up your ass with a jackhammer when it happens.

I would also check my hand brake and make sure it's in working order just in case. It's good to exercise that system every time you drive to keep that cable from rusting up. Just get in the habit of always setting the hand brake when you park, and you'll be fine, and it will be ready if you need it.
 

th797

New member
Joined
Aug 18, 2021
Messages
19
Points
3
Location
Sault Ste. Marie, ON, Canada
Roxor Ownership
Roxor Owner
Have you figured out what's wrong yet?

How steep are the hills you're climbing when this happens?

And it ONLY happens after negotiating a hill, correct?

What I'm thinking is, if the master cylinder is sitting at an angle already when the vehicle is on the level, and the hill you climb exaggerates that angle, you could be having a small amount of brake fluid leaking past your pistons and back into the MC reservoir, and now when you apply your brakes, the fluid in your primary or secondary circuit under the MC reservoir may not be there, and your pedal will go down a lot further than normal.

All MC's have a 60/40 braking ratio. You have 60% on your front wheels and 40% on your rear wheels.

Your front brakes are being applied before your rear brakes so you can maintain steering.

Once you step on your brakes, the primary piston creates hydraulic pressure to apply your front brakes, AND also create hydraulic pressure to be applied against your secondary piston for your rear brakes. Once your rear brakes start to be applied, the pedal gets hard. Thus you have your 60/40 braking ratio in a working system.


Okay, if the front or primary brake hydraulic system fails to build up pressure, you have a steel rod that will EVENTUALLY make connect with the secondary piston and now the mechanical connection starts to push and create hydraulic pressure for your rear brakes.....and the pedal has to go a loooong way before for this to happen.

If your front brakes are working and building up hydraulic pressure, but your rear or secondary circuit has failed, again the pedal will go all the way down until it hits its mechanical stop, and it can build up full hydraulic pressure for your front brakes to be completely applied, but again the pedal has to go a loooong way before this happens.


Now when you release the brake pedal, it comes back to its resting position, BUT it also sucks brake fluid back into those primary and secondary circuits and refills them from the reservoir, and everything is good to go again, and you have normal braking....until the next steep hill.

In any case this is not normal at all, and it "COULD" indicate your MC "COULD" be having leaking issues, and "COULD" fail if the brakes are slammed in an emergency stop.

Next time you go up a steep hill, when you get to the top, apply your brakes rather HARD, not slam them but as you would if you had to make a very quick stop, and see if the pedal goes to the floor again, BUT also see if your front end dips. If it does, your front brake circuit is working, but if it does NOT dip, and you go to the floor and still slow down, your rear brakes are working. All you're doing is trying to figure out which braking circuit could have a possible bleed back issue and do further inspecting and troubleshooting. I would also turn around and go down the same hill and see if it happens again.

It's one thing if you can't start and you can't go, but it's another thing when you can't stop or you can't steer. Both systems have mechanic backups in case of hydraulic failures, and brakes have three really since it has TWO separate hydraulic braking circuits, and a hand brake or emergency brake, but still, it's scary and the ole pucker factor is running a 110% and you couldn't pound a pin up your ass with a jackhammer when it happens.

I would also check my hand brake and make sure it's in working order just in case. It's good to exercise that system every time you drive to keep that cable from rusting up. Just get in the habit of always setting the hand brake when you park, and you'll be fine, and it will be ready if you need it.
Thank you so much for the detailed response, this is very helpful. I will be out in the Roxor this weekend and will try it - it sounds like I could be in for a new master cylinder. I will post any updates here. Thanks again
 
Top