doosan parking brake groan

[kevman6]

We are trying to determine why our Doosan DL220-3 loader ser# DWGCWLATKD1010038 has a loud groan when braking. The sound appears to be from the parking brake during normal braking. The pads are worn, but not at minimum, and the disc is like new. The parking brake works fine when set. I am very familiar with brakes, but not with this loud groan. could weak magnets behind the pads cause this. I don't mind putting in new pads, just wondering what the cause is.

 

[Nige]

It seems strange to me that you suspect a noise from the parking brake when it is the service brakes that are being operated. What type of service brakes does it have.? Dry disc, wet disc, etc.?
If it has wet brakes has the axle oil been changed recently.?

 

[old timer]

Wet disc, change the axle oil first, use UTTO, best to use Doosan oil but I have used Chevron 1000 thf.
It is all in the additives.

 

[Nige]

Where is the parking brake mounted.?
If the noise is truly coming from the parking brake is it located at one end of a driveshaft.?
Is there a possibility that a bearing in the driveline is going out somewhere.?

 

[kevman6]

The noise is in fact coming from the rear wet service brakes. My mistake thinking the noise was resonating from that area. I changed the oil with J20c which the New Holland dealer said to use. The old oil was pretty dirty, and the noise was still there until we drove it a few hundred yards and applied the brakes hard several times. I then was perfect with no noise. We let it sit for two hours and moved it again and the groan is back. It only groans at near stop with light to moderate applications. It does go away again with warming them up with heavy application. If the incorrect oil will do this, I will change it again. The same oil was used in the front axle. It was quiet and still is.

 

[kevman6]

I backed off the parking brake to verify it was not coming from there. I was thinking there may have been a residual pressure problem holding the parking brake partially engaged. Parking brake is working fine They are wet service brakes. Dealer suggested when we changed the oil, to pour some diesel fuel onto the brake discs to flush old oil out. We did that. Still have a groan only when creeping with light application when cold.

 

[Nige]

Cat sell an additive to stop the noise. Can’t remember the part number off hand. Other OEMs probably do as well.

 

[kevman6]

Thank you Nige I will get some I'll let you know how it does

 

[old timer]

Yep... all about the additive.... if you are old enough, think older limited slip chevy axles.
ZF axles can sound like they are breaking apart if you touch the brake and turn. Sounds like the ACME boiler works at low tide.
Good to hear that you have it nailed down!

 

[kevman6]

I'll post results as soon as we find the additive. Thanks for the input

 

[Nige]

Cat Part Number is 1U-9891. If you go looking for an equivalent it's commonly known as an "anti-chatter additive for wet brakes". FWIW I would put it in both axles even thouigh you are only getting noise from one.

By any chance does your loader have a limited-slip differential in the rear axle.?

 

[kevman6]

Not sure, just got it a few months ago. I will put it both axles.