[sagarpadaki]

I am facing an issue with the front brake lever on my Wego which has a disc brake setup. The brake lever becomes hard to press when parked for a few hours. After using the brakes for a while, say 10 minutes of riding, it regains its original firmness and smoothness in operation.

I have bled the brakes, greased the lever, rebuilt the master cylinder assy. The problem gets resolved but reappears after a couple of months. Last time, my trusted mechanic removed and lubed the piston in the MC with a silicone grease. That also worked but now the problem is back after 3 months.

My mechanic is also clueless now.


Please help me out in resolving this issue permanently. Thanks

[vigsom]

I'm no bike expert but based on my experiences on cars, believe that servicing the pistons using only brake fluid is the best way out.

Do you see any pitting or polymeric substance on the piston(s)?

[saket77]

If you’ve rebuilt the master and the problem is still there, you can try servicing the caliper. Also, lubricating the caliper pins is a good idea.

@ VigSom: sir, there are some grease available in market that are compatible with brake fluid. They can be safely used in master cylinder and caliper assemblies. Though not sure, if the mechanic used it.

Regards.

[Researcher]

Originally Posted by sagarpadaki

The brake lever becomes hard to press when parked for a few hours.

I have faced a similar issue with two of the older BS3 Access (front drum) in our family, although your cause maybe entirely different. The front brake becomes hard to press but only when the handle is turned to right. Additionally, the accelerator cable seems to the pulled somehow internally when turning the handle right. This has aggravated a lot in this lockdown, but again seems to go away after a few kilometres. The mechanic confirmed that this is a design flaw in the scooter which requires checking the cables and replacing if required. This solves the issue for a year or two when it again returns. Since you have checked everything, I will suggest to check the cables as well in case in case you haven't already, although I am guessing its fluid in cables of disc compared to wires in case of drums.

[2000rpm]

Originally Posted by Researcher

I have faced a similar issue with two of the older BS3 Access (front drum) in our family, although your cause maybe entirely different. The mechanic confirmed that this is a design flaw in the scooter which requires checking the cables and replacing if required.

This is not a design flaw with the Access, I have an access for more than 7 years now. You should try to change the cables with OEM parts and not local parts. That will solve the issue.

[Researcher]

Originally Posted by 2000rpm

This is not a design flaw with the Access, I have an access for more than 7 years now. You should try to change the cables with OEM parts and not local parts. That will solve the issue.

Thanks for confirming that you do not face this issue. Both the vehicles are serviced with Suzuki itself with parts from them only. I blindly trusted the guy's explanation for the 2-3 times he changed the cables over the last 8-9 years, especially when both our vehicles had the exact same issue! I will check other Accesses at the service centre next time I visit.

[sagarpadaki]

Originally Posted by vigsom

I'm no bike expert but based on my experiences on cars, believe that servicing the pistons using only brake fluid is the best way out.

Do you see any pitting or polymeric substance on the piston(s)?

The piston is smooth and clean. Bajaj sells a silicone grease along with the MC rebuild kit. I had some left over . The mechanic used the same.

Originally Posted by saket77

If you’ve rebuilt the master and the problem is still there, you can try servicing the caliper. Also, lubricating the caliper pins is a good idea.

@ VigSom: sir, there are some grease available in market that are compatible with brake fluid. They can be safely used in master cylinder and caliper assemblies. Though not sure, if the mechanic used it.

Regards.

I serviced the caliper recently, removed the caliper assy and cleaned every parts, including the slot for the pins with APC and brake cleaner, dried everything up, used fresh brake caliper compatible silicone grease and assembled everything back.

Apart from the brake hose and rebuilding the caliper assy, I think I have tried everything.

Any suggestions on doing something differently or trying out something else, I am open to them

[srini1785]

Originally Posted by sagarpadaki

I am facing an issue with the front brake lever on my Wego which has a disc brake setup....

I am not familiar with TVS Wego firsthand so my reply comes with riders.

A hydraulic brake system ( as in wego) breaths air in the master cylinder as the piston moves in and out. If for some reason the air is not exhausted out but remains trapped in either the caliper or the cylinder then the brakes becomes very hard. As you push through the lever , air is slowly forced out (or in) and there is space available for the fluid to move and subsequent actions become more easier.

Unlike a pneumatic circuit , which exhausts used air through the valve silencers, hydraulic system is a closed loop system with the fluid returning back to the chamber. if the chamber has trapped air, then the fluid encounters resistance to movement.

In industrial hydraulic power packs , the hydraulic fluid tank usually has a vent to atmosphere to enable the fluid back to the chamber.

Just my guess.

[vrprabhu]

Have no idea which brand of brakes are fitted on the Wego, but by any chance, could there be a problem with the air bleed screw? Are its threads OK and is it sitting flush? (had a similar problem once; the fluid in the caliper was turning gel like, because of moisture creeping in!). Please also check whether the rubber cap on the reservoir is OK.

There is definitely some air getting trapped in the circuit - a leakage would have resulted in loss of fluid.

Another thought - is the fluid used of the correct specification (dot 3 / dot 4?)

[vrprabhu]

Originally Posted by sagarpadaki

.... Apart from the brake hose and rebuilding the caliper assy, I think I have tried everything....

Originally Posted by srini1785

... If for some reason the air is not exhausted out but remains trapped in either the caliper or the cylinder then the brakes becomes very hard. As you push through the lever, air is slowly forced out (or in) and there is space available for the fluid to move and subsequent actions become more easier ...

Another thought just occurred to me -
check the routing of the rubber hose from the cylinder to calipers and ensure that they are not getting crimped (for lack of a better word). There would be at least a couple of rubber bushes with metal clamps to hold the hose secure - could these be the culprits? If so, the problem is most likely to occur when the steering is locked only on one side and not locked either ways.

[sagarpadaki]

Originally Posted by vrprabhu

Another thought just occurred to me -
check the routing of the rubber hose from the cylinder to calipers and ensure that they are not getting crimped (for lack of a better word). There would be at least a couple of rubber bushes with metal clamps to hold the hose secure - could these be the culprits? If so, the problem is most likely to occur when the steering is locked only on one side and not locked either ways.

Using DOT 4 fluid. Flushed with fresh fluid 3 months ago when the master cylinder piston was removed and greased. The brake hose is not pinched anywhere. It has the rubber bushes that route the hose along the body from the caliper to the master cylinder and it is unhindered.

The problem occurs when I start to ride after the scooter is idle for a few hours or overnight. If the hose was getting pinched then it should occur only when the scooter handle is turned to one side, right?

The bleeder/air screw looks fine to me. The dust cap is present. When I last bled the brakes the brake fluid was neat and runny. No gel formation was observed

[vrprabhu]

Wild guess -

(1) Could it be a problem of sticky brake pads? Did you check the pads? Running the bike heats up the disc, which results in the pads sticking to the disc once it cools down?

(2) Retraction issues with the piston - more likely if it is a twin pot caliper, where the scenario is one works and the other isn't.

(3) Check the caliper mounting bolts (on the fork) - there should be no play. The bolts have a copper washer - to ensure that the bolts are clamped correctly.

[vrprabhu]

Any updates on this, Sagar. Is the issue identified and resolved?

[Rahul Bhalgat]

Originally Posted by sagarpadaki

I am facing an issue with the front brake lever on my Wego which has a disc brake setup. The brake lever becomes hard to press when parked for a few hours. After using the brakes for a while, say 10 minutes of riding, it regains its original firmness and smoothness in operation.

Hi sagarpadaki,
If the issue is still persisting, you can check the following.

Does the hard feel on the lever vanish because of repeated pulling on the lever in those 10 minutes or does it vanish because of wheel rotation in those 10 minutes? You can find this out by pulling the lever for around 100 - 200 times in the morning with the scooter stationary. Please pull the lever gradually, like you pull while braking. Don't be fast or jerky.

And do you think that the problem is less severe (or the hard feel vanishes earlier) in the summer than in the winter? I mean, does the hard feel ease out because of warming?

This shall give you a clue about possible cause and location of the problem.

[sagarpadaki]

Originally Posted by Rahul Bhalgat

Hi sagarpadaki,
If the issue is still persisting, you can check the following.

Does the hard feel on the lever vanish because of repeated pulling on the lever in those 10 minutes or does it vanish because of wheel rotation in those 10 minutes? You can find this out by pulling the lever for around 100 - 200 times in the morning with the scooter stationary. Please pull the lever gradually, like you pull while braking. Don't be fast or jerky.

This shall give you a clue about possible location of the problem.

Yes the issue persists when the brake lever is pumped when stationary and even when the scooter is ridden around a while.

I am planning to change the brake fluid hose this week. The caliper is fine and is not binding. It moves freely. Hopefully, this should solve the issue.