[Warking]

Hey everyone!
I'm Warking. A long time reader of Team-BHP, and finally a member of it.
I own a 2017 Bajaj Avenger Street 150 BS4. I recently got my bike service in June at the ASC in Gurgaon. The bike was due for its service for past two months, but wasn't able to make time for it.
I took my bike for its annual service. Got the engine oil replaced and both brake pads were nearing their end of life and hence got them changed. The rear brake being a drum brake was replaced easily. But when they were trying to remove the front caliper, it wasn't budging open, no matter what. They tried to pry it open with force, tried to open it by trying to open with a hammer, but it still didn't. They advised to get a new caliper.
They installed a fresh caliper. I verified the part number before installing. Now for the past one month, I've been noticing weird dust trail on my front disc. Looking at it, I felt something was off with the front brake pad and hence went to the ASC again yesterday.
When they pulled out the caliper, well the top half of the brake pad looked fresh, while the lower half, it crossed its half life. These pads were just 2500+km old and usually have a life of 18000-20000km.




After looking at the pads, I don't think I have ever seen this type of wear on them. Upon asking why this happened, the SA didn't have any answer and just said that it could be due to dust and water. He suggested to get the pads replaced and I gave them a go ahead to change new pads. Due to this uneven wear, there was a little uneven wear on the disc as well, which they manually sanded. When they were changing them, I had requested them to drive the bike to ensure this isn't happening again.

New pads vs old worn out pad


After rolling the front wheel few times and applying the brake so that the wear pattern can be shown on the new pads, the same pattern was discovered, as in the image below.


This caused both the SA and SA's Supervisor to go into blank mode as they failed to understand what caused this. They tried to check the caliper whether it was applying even pressure on the pads or not. Nothing wrong was found there.
Due to the closing time of the ASC they advised to continue using the old pads as they still have some life left and leave the bike for a detailed inspection as to what this is causing. Now, I don't have my weekends off, neither I've any fixed off days due to my work line, which makes it difficult for me to leave my bike for inspection nor I've another vehicle to leave this for inspection and use the other for my daily commute.
Has anyone seen this kind of wear pattern in their pads before, and what step should I take next?

[shancz]

Welcome to TBHP

Just looking at your pads its obvious that :
- They're not inserted properly, the entire pad surface should contact the disk rather than 50-60% in your case. Hence that distinct line where the disk ends.
- Since they've changed the pads and then the issue happened I am assuming they've messed something up then. Its obvious that something is pressing the brake pads to your disk continuously which can be the piston/caliper/disk(bent), master cylinder or some issue in the hydraulic line . This is something they've to check and fix.

Easy to test:
1. Rotate your front wheel while on the center stand and it won't rotate freely.
2. If it does then apply the front brake and then observe it should stop then and won't be rotating freely after that.

If only 2 happens then the have to check the master cylinder area as the pressure isn't getting released. If 1 happens then it could be either, start by checking if the one or both pistons aren't sticking out of their normal positions.
I expect this to be the cause but can't say for sure.
I also feel that the caliper which they changed wasn't needed as well. Calipers last very long. If they have that lying around then once the issue is resolved, test with that as well. They should return the caliper which they changed if its true.

A normal worn out brake pad should look like the one in the video below, right at the start.
Check it out more info on the process.
Credits to Providers :

YouTube : HeartBrokenBiker

[sagarpadaki]

The problem is in the brake disc/rotor. Not the pads. Changing the caliper was totally unnecessary. Looks like a warped rotor.

Bajaj sells complete caliper rebuild kits. Unless the caliper is structurally damaged, it need not be discarded.

[Warking]

Originally Posted by shancz

Easy to test:
1. Rotate your front wheel while on the center stand and it won't rotate freely.
2. If it does then apply the front brake and then observe it should stop then and won't be rotating freely after that.

While I was at the ASC yesterday, the did this. After the new pads were installed, the wheel rotated freely, but as soon as the brake was applied and let go, the freeness wasn't the same.
I did ask them to show me if both the cylinder were working the way they are supposed to before installing the caliper on the rotor and the cylinders were working well.

I agree that calipers last very long. And that is why initially I was opposed to it being changed. But even after trying every method for an hour, it didn't open,nor they were able to take the old pads out successfully. That is when I gave them a go ahead to change it.
As I had my caliper changed in June, they definitely won't be having it. But on my next visit, I'll ask them to change the caliper again as this could be a faulty one.

[shancz]

Originally Posted by Warking

As I had my caliper changed in June, they definitely won't be having it. But on my next visit, I'll ask them to change the caliper again as this could be a faulty one.

I don't think the problem is in your caliper. It should be somewhere else and I would say check the disks for warping as mentioned by sagarpadakki. But discount the issues with misadjusted pistons before moving away from the calipers.

If you have the bike then you can try rotating and look for abnormalities with the disks. Have someone hold the handlebar straight and observe the rotating disk if you notice any deflections. Also share a picture of your discs and the brake system.

Did they bleed the brakes or replace the brake fluid in that service?


Also do check this link out and dive straight into the multi quote feature (How to MULTI-QUOTE (when replying to a thread) on Team-BHP) to avoid overburdening the mods

[tanayr]

Can you put in a picture of the right fork and caliper (from the side)? I have a feeling the Bajaj svc guys replaced your caliper with maybe a 220 one...

[SS-Traveller]

Originally Posted by Warking

They advised to get a new caliper.
They installed a fresh caliper. I verified the part number before installing.
...
Has anyone seen this kind of wear pattern in their pads before, and what step should I take next?

This is a case of wrong / mismatched caliper & disc combination. The caliper and pads are wider than the available disc surface, so the outer part of the pads is not engaging with the disc at all, The central mark on the pad is actually where the edge of the disc is.

Get your service centre to fit matching discs, calipers and pads.

[shancz]

Good point by SS-Traveller above.
Somehow didn't occur to me that a mismatching part was fixed at an ASC, my bad.
It could just be a case of a larger and possibly thicker (incompatible) caliper-pad setup which is causing the issue.
Since you weren't having the issue prior to the change this seems to be the culprit and not the master cylinder etc.

[sagarpadaki]

Bang on SS-Traveller.

Good analysis.

I think the Bajaj service center have installed a caliper for some other Bajaj bike onto the OP's bike.

[MaheshY1]

Looks like your bike has a smaller disc than it should have. Compare with other Avenger models in the service center. It looks like it has a 1cm smaller disc. Figure out which disc will fit and buy a new one to replace this disc. This should solve the problem. When you replace the disc, also replace the pads for full contact.

[Chandrahas]

I think it's due to a mismatch between the rotor and the brake pads. Avenger 220 comes with a 280mm disc while the Avenger 150 with a 240mm disc, so they might have used the pads of the 220cc Avenger.
Also, if you see, the unused portion is around 20% of the used portion.

[rayvonnee]

You can check 99rpm.com so as to understand the part numbers in a better way. The part diagrams for Avenger Street 150 are available.
Kindly check this - https://www.99rpm.com/bajaj/parts.ht...cat=625#page=1

[arijitkanrar]

Originally Posted by Chandrahas

I think it's due to a mismatch between the rotor and the brake pads. Avenger 220 comes with a 280mm disc while the Avenger 150 with a 240mm disc, so they might have used the pads of the 220cc Avenger.
Also, if you see, the unused portion is around 20% of the used portion.

It sounds plausible. The images even support.
But wouldn't the brake caliper size also differ? Also if the calipers are of smaller size, then how would it fit larger brake pads?
If the calipers have the same size for the larger and smaller brake discs, then this is definitely a good thing to check.

[Chandrahas]

Originally Posted by arijitkanrar

It sounds plausible. The images even support.
But wouldn't the brake caliper size also differ? Also if the calipers are of smaller size, then how would it fit larger brake pads?
If the calipers have the same size for the larger and smaller brake discs, then this is definitely a good thing to check.

Same calliper can house different pad sizes. For ex : the calliper size is same for all the KTMs.

[VijayAnand1]

Originally Posted by Warking

They advised to get a new caliper.
They installed a fresh caliper. I verified the part number before installing. Now for the past one month, I've been noticing weird dust trail on my front disc.

I think somewhere here things have taken a turn for the worse. You're either running an incompatible caliper or a brake pad/caliper combo that isn't sized for your rotor. Is your vehicle a new one or a used one? Have you replaced your disc rotor?

Usually pads wear unevenly to an extent owing to piston pressure and how well the caliper slide and return, this, to an extent is normal. Having a perfect arc dug into the pads, as in your case, can be done only by the outer circumference of the rotor constantly grazing and digging into the pads. There is no other way something can dig and eat into a pad other than a rotor edge constantly subjected to braking and grazing.

Start off with the parts catalog, make sure the rotor, the brake pad, and the caliper are as per the model and not a new updated model. Kick it off from there, good luck.

Cheers!
VJ