|
|
|
|
| Author |
|
|
Registered
Join Date: Sep 2005
Location: So. Cal.
Posts: 11,239
|
Strange Brake Caliper Issue
In support of construction efforts we run a fleet of International flat bed trucks. They are robust and stout as can be - they have 4 wheel disk brakes. The following photos are of the second caliper that has gone bad in the last six months. To our eyes it looks like the steel pistons have crystalized - the leading edges are dissolving into a powder. We have confirmed we are using the right brake fluid, and we have never had this problem with any other calipers in the fleet. Any ideas from the brain trust?
 
__________________
David 1972 911T/S MFI Survivor |
||
07-10-2012, 10:31 AM
|
|
|
Registered
Join Date: Jul 2003
Location: Valencia Pa.
Posts: 8,847
|
Are you sure they are stainless? . I have seen caliper pistons that look like that when the caliper stuck and overheated. Your dust boots do not look to have been overheated though. Is there any evidence of overheating, at either the rotor, pads, or caliper piston dust boots? How about the slides on the brake caliper bracket? Do they move free?
__________________
No left turn un stoned |
||
|
07-10-2012, 10:39 AM
|
|
|
Registered
Join Date: Jan 2005
Location: Minneapolis
Posts: 7,482
|
Looks like galvanic corrosion from dissimilar metals.
Are you running the o.e. pads?
__________________
I love you guys outside this forum  -Eric |
||
|
07-10-2012, 10:40 AM
|
|
|
Registered
Join Date: Sep 2005
Location: So. Cal.
Posts: 11,239
|
The dust boots are fine. We are running a variety of pads, but I certainly assumed all pads and pistons were steel. I have no doubt that they get hot, but these trucks are heavily loaded most of the time. I certainly agree with the galvanic corrosion, but I can't explain why it has just started now.
__________________
David 1972 911T/S MFI Survivor |
||
|
07-10-2012, 10:45 AM
|
|
|
Gary H 1978 911 SC
Join Date: Oct 2003
Location: Fort Worth Texas
Posts: 1,306
|
They look aluminum and have a bad case of galvanic corrosion. Put a magnet on them and see if they have any iron in them.
|
||
|
07-10-2012, 11:25 AM
|
|
|
You do not have permissi
Join Date: Aug 2001
Location: midwest
Posts: 39,846
|
Chinese pot metal. Everything goes in.
|
||
|
07-10-2012, 01:04 PM
|
|
|
|
Registered
Join Date: Sep 2005
Location: So. Cal.
Posts: 11,239
|
AS far as we know these are the stock calipers. I will check them out tomorrow and see if they contain iron.
Our local brake supplier says that he sees this often - that the pistons are of a material that does its best not to transfer heat to the brake fluid. What really bothers me is we have never seen this before. Will be checking all trucks in the fleet for the remainder of the week.
__________________
David 1972 911T/S MFI Survivor |
||
|
07-10-2012, 01:19 PM
|
|
|
Air Medal or two
Join Date: Jul 2003
Location: cross roads
Posts: 14,077
|
salt and aluminum..........they are Al.
__________________
D troop 3/5 Air Cav,( Bastard CAV) and 162 Assult Helicopter Co- (Vultures) South of Saigon, U Minh Forest, Delta, and all parts in between |
||
|
07-10-2012, 01:50 PM
|
|
|
Registered
Join Date: Sep 2005
Location: So. Cal.
Posts: 11,239
|
Salt. If you mean from ice etc we don't use that in So Cal.
__________________
David 1972 911T/S MFI Survivor |
||
|
07-10-2012, 01:53 PM
|
|
|
Unoffended by naked girls
|
I believe those pistons are some sort of phenolic plastic. GM used that material for a number of years.
__________________
Dan 1969 911T (sold) 2008 FXDL www.labreaprecision.com www.concealedcarrymidwest.com |
||
|
07-10-2012, 01:55 PM
|
|
|
Registered
Join Date: Sep 2005
Location: So. Cal.
Posts: 11,239
|
Plastic? Wow! Really?
__________________
David 1972 911T/S MFI Survivor |
||
|
07-10-2012, 02:04 PM
|
|
|
Registered
Join Date: Jul 2003
Location: Valencia Pa.
Posts: 8,847
|
Quote:
__________________
No left turn un stoned |
||
|
07-10-2012, 02:13 PM
|
|
1969 Porsche 911 T 2.0 L
