Pelican Parts
Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   Pelican Parts Forums > Porsche Forums > Porsche 964 & 993 Technical Forum


Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Registered User
 
Join Date: Jan 2009
Location: DC
Posts: 1,175
Garage
964/993 owners test your ABS and do it regularly.

Hello Friends

We just had some snow in DC and I have a 300 foot long driveway, Perfect place to test my ABS, I took my 965 out this morning did a few tests runs and my ABS seems to work, The pedal did what I expected just like my 2017 Jetta that I test just prior to compare , I even opened the door to see if the rear ABS was working , All good, back in the garage she went.

The exercise got me thinking. Firstly how many of us drive around not knowing if the ABS is working or not.. The only reason they would seize like this is because they haven't been operated on a regular basis?

Conclusion...test your ABS and do it regularly.
__________________
1986 944 turbo -first car
1997 993 Cab 6 speed-sold
1992 964 C2 turbo
SOLD, 911GT ,CIS, 428 fwhp 450 trq, Carrillo rods, 964 cams, TT retainers,7.5 comp 1.1 bar boost 320 ml black fuel head 009 injectors, 044 pumps, 60-1 T4/T3 dual scroll turbo

Last edited by heliolps2; 01-23-2018 at 08:29 AM..
Old 01-20-2018, 06:13 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #1 (permalink)
Moderator
 
Bill Verburg's Avatar
 
Join Date: Dec 2000
Posts: 22,823
Garage
Quote:
Originally Posted by heliolps2 View Post
Hello Friends

We just had some snow in DC and I have a 300 foot long driveway, Perfect place to test my ABS, I took my 965 out this morning did a few tests runs and my ABS seems to work, The pedal did what I expected just like my 2017 Jetta that I test just prior to compare , I even opened the door to see if the rear ABS was working , All good, back in the garage she went.

The exercise got me thinking. Firstly how many of us drive around not knowing if the ABS is working or not. Secondly, the pump and these pistons are 'dry'. They are not lubricated by brake fluid. The only reason they would seize like this is because they haven't been operated on a regular basis?

Conclusion...test your ABS and do it regularly.
The ABS pump is totally saturated w/ brake fluid, unless you get air into the system somehow. It couldn't work otherwise
__________________
Bill Verburg
'76 Carrera 3.6RS(nee C3/hotrod), '95 993RS/CS(clone)
| Pelican Home |Rennlist Wheels |Rennlist Brakes |
Old 01-22-2018, 05:58 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #2 (permalink)
Registered User
 
Nine9six's Avatar
 
Join Date: Jun 2004
Location: So Cal
Posts: 2,778
Garage
For brake and clutch slave fluid flushes, if you don't have a Bosch hammer, PST2, PIWIS diagnostics tool; or physically exercise the ABD and/or ABS systems as mentioned above by the OP, you will eventually end up with a non-functioning, gummed up system.

I would recommend exercising the abs/abd systems AFTER brake fluid flush to purge those components of the old brake fluid, and in the process refilling the system with the fresh brake fluid.

I would then, re-bleed the brakes to purge the system of the old brake fluid that was just exhausted by the ABS ABD systems components.

Here is an old Rennlist thread on the subject...

https://rennlist.com/forums/993-forum/489683-solution-for-soft-brake-pedal-caused-by-abs-pump.html

Just my $.02
__________________
If it flows, it goes. If its smooth, it moves. Any questions?
96 993 C2 (Current)
87 911 Factory Turbo-Look Cab (Sold)
85 911 Factory Turbo-Look Targa (Gone)

Last edited by Nine9six; 01-26-2018 at 06:37 PM..
Old 01-26-2018, 06:24 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #3 (permalink)
Moderator
 
Bill Verburg's Avatar
 
Join Date: Dec 2000
Posts: 22,823
Garage
Quote:
Originally Posted by Nine9six View Post
For brake and clutch slave fluid flushes, if you don't have a Bosch hammer, PST2, PIWIS diagnostics tool; or physically exercise the ABD and/or ABS systems as mentioned above by the OP, you will eventually end up with a non-functioning, gummed up system.

I would recommend exercising the abs/abd systems AFTER brake fluid flush to purge those components of the old brake fluid, and in the process refilling the system with the fresh brake fluid.

I would then, re-bleed the brakes to purge the system of the old brake fluid that was just exhausted by the ABS ABD systems components.

Here is an old Rennlist thread on the subject...

https://rennlist.com/forums/993-forum/489683-solution-for-soft-brake-pedal-caused-by-abs-pump.html

Just my $.02
That's is true, the ABS working part is either 3 or 4 main pistons whose function is to connect or disconnect the pedal and individual caliper pistons from each other There are also a proportional # of aux pressure control pistons. All of the pistons create numerous pockets of normally stagnant brake fluid. The default is pedal connected to calipers until the wheel sensors signal an excessive difference in wheel speeds, at which point the brain tells an offending piston to disconnect that caliper from the pedal. Over time when not flushed a waxy substance and moisture builds up in the various piston bores, this substance interferes w/ and degrades ABS performance.

Here is a schematic of a 3 channel abs
__________________
Bill Verburg
'76 Carrera 3.6RS(nee C3/hotrod), '95 993RS/CS(clone)
| Pelican Home |Rennlist Wheels |Rennlist Brakes |
Old 01-27-2018, 06:43 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #4 (permalink)
Registered User
 
Join Date: Nov 2013
Location: Torquay , UK
Posts: 42
Garage
Interesting. Diagnostic tools are mentioned. Been meaning to get one to amongst otherwise things make bleeding of the C4 AWD solenoids easier. When it says they have ABS function does this mean the activation of solenoid valves mentioned above? Also, this from A Streathers book: 'Automatic ABS system self testing at 7 kph/4 mph can be felt by the driver, because the return pump in the ABS hydraulic united will run briefly.' This is apparantly testing the wheel sensors. Any light on this? How should it feel?
Old 01-28-2018, 07:34 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #5 (permalink)
Registered User
 
Nine9six's Avatar
 
Join Date: Jun 2004
Location: So Cal
Posts: 2,778
Garage
Yes.
I believe this will feel like when the ABS is actuated/working. (Quick pulsing/shuddering feel at the brake pedal).
__________________
If it flows, it goes. If its smooth, it moves. Any questions?
96 993 C2 (Current)
87 911 Factory Turbo-Look Cab (Sold)
85 911 Factory Turbo-Look Targa (Gone)
Old 02-09-2018, 05:07 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #6 (permalink)
 
Registered User
 
hkspwrsche's Avatar
 
Join Date: Jan 2004
Location: Richmond,Va
Posts: 910
Quote:
Originally Posted by Paperboy View Post
Interesting. Diagnostic tools are mentioned. Been meaning to get one to amongst otherwise things make bleeding of the C4 AWD solenoids easier. When it says they have ABS function does this mean the activation of solenoid valves mentioned above? Also, this from A Streathers book: 'Automatic ABS system self testing at 7 kph/4 mph can be felt by the driver, because the return pump in the ABS hydraulic united will run briefly.' This is apparantly testing the wheel sensors. Any light on this? How should it feel?
Never noticed
__________________
Harold
Old 02-15-2018, 04:24 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #7 (permalink)
Registered User
 
Nine9six's Avatar
 
Join Date: Jun 2004
Location: So Cal
Posts: 2,778
Garage
Quote:
Originally Posted by hkspwrsche View Post
Never noticed
Hmm, that's not a good sign...

I would take the car out onto some snow or wet surface and actuate the ABS by hard braking (hard enough to lock up the wheels).

I don't recommend doing this in the dry because if the ABS doesn't work, you'll end up flat spotting the tires.

If the tires need replacing, test to your heart's content.
__________________
If it flows, it goes. If its smooth, it moves. Any questions?
96 993 C2 (Current)
87 911 Factory Turbo-Look Cab (Sold)
85 911 Factory Turbo-Look Targa (Gone)
Old 02-16-2018, 04:10 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #8 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 06:46 PM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page
 

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.