Low speed brake squeal rant

The forum for all of your technical questions on your classic FIAT autos
User avatar
jseabolt
seimila club
Posts: 6074
Joined: Sun Jan 24, 2016 7:27 pm
Last Name:

Low speed brake squeal rant

Post by jseabolt » Thu Nov 08, 2018 9:18 am

Years ago some people were going on about how good Axxis metal master pads we're so I put some on my Fiat Spider and they squealed really bad under low speed braking so I went back to regular pads.

So my wife's 2016 Nissan Juke she bought used was doing the same thing. She had been on me for some time to replace the pads

So yesterday I replaced the pads on all four wheels with Advance Auto ceramic Gold pads. I also used some of that CRC disc brake squeal stuff between the pads and calipers for good measure.

No more brake squeal. I'm not sure which fixed the problem.

These pads must have been the original pads. They had only 2 mm of wear and had Nissan on them. The only thing I found different was the Nissan pads had a thin piece if sheet metal that goes between the backing plates and the calipers. I have no idea if this was what was causing the squeal or the type of friction material.

Is this squeal usually caused by the friction material or something else?

The only other time I've seen this low speed brake squeal was when using those metal master semi-metalic pads.

No sure if the Nissan pads we're semi metallic or not. The friction material looked the same as the Advance Auto pads.

Just curious.
User avatar
bartigue
cinquemila club
Posts: 5786
Joined: Sat Jan 23, 2016 11:49 pm
Last Name: Artigue
First Name: Bradley
Contact:

Re: Low speed brake squeal rant

Post by bartigue » Thu Nov 08, 2018 9:55 am

Squeal is vibration between the pad and the caliper.
-----------------------------------------------------------
Brad Artigue
1982 Spider 2000
I've restored, worked on, sold, bartered, and bled for:
1970, 1979, 1980, 1981, 1982 124 Spiders -- 1969, 1970 850 Spiders -- 77 X1/9
http://fiat.artigue.com
User avatar
rridge
tremila club
Posts: 3372
Joined: Sun Jan 24, 2016 9:18 pm
Last Name: ridge
First Name: richard

Re: Low speed brake squeal rant

Post by rridge » Thu Nov 08, 2018 2:42 pm

Brakes are inherently noisy. Few automotive complaints are as common and as universal across makes, models and years as noisy brakes. Rubbing brake shoes or pads against cast iron generates sound. A large pieces of cast iron, whether brake disc or frying pan is a near perfect noise amplifier. Using a lubricating spray on the disc or roughing up the disc or pad surface will usually make the sound go away for a short time but it will come back. Longer term solutions usually involve either preventing the pad from bonding to the caliper piston by using some kind of high temp material on the back of the pad or by changing the pad material or weight. Semi-metallic pads are particularly prone to brake noise.
Richard
'81 Turbo Spider
Rockville, MD
User avatar
Grothmanr
Posts: 12
Joined: Mon Oct 22, 2018 8:12 pm
Last Name: Grothman
First Name: Rob

Re: Low speed brake squeal rant

Post by Grothmanr » Thu Nov 08, 2018 8:48 pm

My Fiats haven't squealed, but I have placed a piece of duct tape between the pad and the caliper to eliminate low speed squeal. It works on Yamahas and Volvos.
Rob in Green Bay

1975 128 - RIP
1975 124 Coupe - Sunday Driver
1979 128 - Sold
1998 Jeep TJ - Daily Driver
User avatar
davedecker4
Posts: 543
Joined: Sun Jan 24, 2016 11:05 am
Last Name: Decker
First Name: Dave

Re: Low speed brake squeal rant

Post by davedecker4 » Sat Nov 10, 2018 1:27 am

Can you explain? Where exactly and how does it work?
Dave Decker
a 'couple' Fiats and Lancia's
User avatar
beek
Posts: 105
Joined: Mon Aug 28, 2017 7:53 pm
Last Name: Beeken
First Name: Randy

Re: Low speed brake squeal rant

Post by beek » Sat Nov 10, 2018 7:58 am

Being that I am a High School Auto shop teacher and this week we have been teaching brakes, Ill chime in...LOL

Brake pads are constantly trying to follow the rotor when they are in touch with the rotor. The pad bracket keeps them in place. For brake pads to work effectively the have to be able to return to the "rest" position. Meaning not stick when pushed towards the rotor. So there is built in slop in the system. So the pads are basically vibrating in the direction of the rotors motion and then returning back to the bottom of the bracket. This happens very fast as you could imagine. The caliper is mounted to the bracket and also has the ability to slide and has some slop up and down as well. these motions combined cause harmonics. These harmonics are known as "squeal" the frequency is high because of the rapid actions taking place. Once the brakes are applied hard the parts become less able to move and the "squeal" goes away. Manufacturers address this "squeal" in various ways. They use anti vibration clips, they can use an additional backer on the pads, and some use a membrane. Some use more than 1 way. Disc brake quiet works very well, It creates a sticky membrane between the pad and caliper which dampens the vibration. Duct tape will also work, It creates a membrane between the pad and caliper.

I hope this was helpful. There are a few other technical nuances at play but this is the basics of it.
2018 Abarth Spider, Daily
2016 500X wifes daily
2014 500L daughters daily
1982 Zagato (+2 parts cars)
1978 Spider Sons daily
1975 Spider Restored
(5) 1976 Lancia Scorpions, 3 that are being worked on to drive
(5) spider parts cars.
User avatar
Grothmanr
Posts: 12
Joined: Mon Oct 22, 2018 8:12 pm
Last Name: Grothman
First Name: Rob

Re: Low speed brake squeal rant

Post by Grothmanr » Sat Nov 10, 2018 8:55 am

What Beek said.
Rob in Green Bay

1975 128 - RIP
1975 124 Coupe - Sunday Driver
1979 128 - Sold
1998 Jeep TJ - Daily Driver
User avatar
rridge
tremila club
Posts: 3372
Joined: Sun Jan 24, 2016 9:18 pm
Last Name: ridge
First Name: richard

Re: Low speed brake squeal rant

Post by rridge » Sat Nov 10, 2018 10:07 am

My Spider has had a tendency to squeal the rear brakes on light application after they have warmed. I've noticed that this is a common Spider characteristic.

New calipers, pads, and discs have not changed the squeal for very long. What's puzzling that that the same rotors, pad materials and brake hardware are used on both front and rear yet I never hear the front brakes squeal. Nor have I noticed it on X1/9's which share a lot of the same hardware.

When I've disassembled and inspected I've found the rear pads glazed. Removing the glaze takes the squeal away but only for a short time. I've thought about experimenting with softer organic pads on the back, which would also help the parking brake hold a little better but have never acted on it. Unfortunately new rear pads are usually a tight fit on a Spider which doesn't much room for playing with coatings or shims on the back of the pads.
Richard
'81 Turbo Spider
Rockville, MD
User avatar
jseabolt
seimila club
Posts: 6074
Joined: Sun Jan 24, 2016 7:27 pm
Last Name:

Re: Low speed brake squeal rant

Post by jseabolt » Sat Nov 10, 2018 4:40 pm

I was going through a box of stuff a few minutes ago and found that box of Axxis metal master pads! Or at least the box they came in. Assuming they are the same pads I removed. I can't understand why I saved the box. I guess my hoarder mentality!

You would think as much R and R Nissan puts into their cars, brake squeal would be something simple.

The Advance Auto pads and the CRC stuff seem to be doing the trick.
User avatar
beek
Posts: 105
Joined: Mon Aug 28, 2017 7:53 pm
Last Name: Beeken
First Name: Randy

Re: Low speed brake squeal rant

Post by beek » Sat Nov 10, 2018 7:40 pm

if you decide not to use the metal master pads I am interested in them, I love the way they work
2018 Abarth Spider, Daily
2016 500X wifes daily
2014 500L daughters daily
1982 Zagato (+2 parts cars)
1978 Spider Sons daily
1975 Spider Restored
(5) 1976 Lancia Scorpions, 3 that are being worked on to drive
(5) spider parts cars.
Post Reply

Who is online

Users browsing this forum: No registered users and 5 guests