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My 964 C4 ABS booster pump has died on me, pic below is the part in question, for illustration purposes.
No stock in the UK or EU and they're on back order with the Porsche factory in Germany until the beginning of August.
Don't even know if they'll be available then, that's just the date for an update...
So I've been looking at used parts, as I'd like the 964 back on the road ASAP.
I also looked at rebuilds, but that's for a different thread as there is plenty of posts covering that.
The 964 part has been superseded by a 993 part number, see below.
ABS booster pump part# 96435590101 superseded by 99335595302 listed for 964: C4/RS/Turbo-look 993: C4/C4S/RS
ABS booster pump part# 99335595350 superseded by 99335595351 listed for 964: none993: Turbo-look/Turbo
I'm trying to find out exactly what the difference is between the two current part numbers 99335595302 and 99335595351
As the 993 Turbo is 4WD and so are the 964 C4 nd 993 C4 (obviously).
Can I use the 993 Turbo ABS booster pump on my 964 C4????
I've read elsewhere on Rennlist that there is a difference in the hydraulic assistance boost ratio.
964: C4/Turbo 993: C4/C4S/Turbo all utilize the hydraulic brake booster with a power boost ratio of 4.8 964: RS/Cup/RS3.8/RSR 993: RS/RSR/GT2 all utilize the hydraulic brake booster with a power boost ratio of 3.6 964 C2 as a comparison the vacuum assisted brake booster ratio is 3.0
Apparently the 3.6 ratio is the sweet spot, but the 4.8 lists both the 964 C4 and the 993 Turbo, so this can't be the only difference or someone has the details wrong
if dropping the ratio to 3.6 would not the ECU need 'updating' should it become confused from a different booster pump output pressure? Out of interest where did you read that 3.6 was the sweet spot?
First off, thanks for the responses guys, 240+ reads and only 2 responses so far...
I think this is a bit of a grey area!
Originally Posted by LM964
if dropping the ratio to 3.6 would not the ECU need 'updating' should it become confused from a different booster pump output pressure? Out of interest where did you read that 3.6 was the sweet spot?
I would test the switch , pulled the switch on mine and swapped and presto pump resumed operation , just an FYI , Bert
oh and yes wouldn’t hesitate to swap from a turbo , Bert
My Indy tested everything and said the booster pump was dead.
I ended up getting a new item at a reduced price from ECS in the states, great service from ECS for EU customers
Just waiting for it to be fitted and tested this week by my Indy...
With this partnumber, you should find some stuff. Had my pressure housing separated from the pump this spring and no fancy **** there... is tight again and works well. I was just curious what is inside and opened it... The Jag parts seems to be the same at the motor-side...
With this partnumber, you should find some stuff. Had my pressure housing separated from the pump this spring and no fancy **** there... is tight again and works well. I was just curious what is inside and opened it... The Jag parts seems to be the same at the motor-side...
Yea I found a few posts stating that Jag, Range Rover and Ferrari all used the same part, during the same period.
The Range Rover ones appear to be the cheapest!
Hi Guys,
I also have the interlock and brake lights come on.
So far, I replaced the R51 relay, but the warning lights still come on.
Would it make sense to replace the relays on the pump itself?
Thanks for any suggestions.
The failure point on these pumps, assuming your control electronics are good, is usually the locks (switching solenoids) or the relays.
I replaced my ABS pump (c2 however) with a take off I got on eBay for a fraction of the cost.
My original pump ran fine, and the front L/R channels worked fine, but the locks on the rear channel were frozen, probably from not bleeding the brake circuit to schedule.
You can try swapping the relays, they are pretty standard parts.
Just guessing here but the 993 turbo seems to be have a specific part number it might be due to 2 things switching from a 3 to a 4 channel ABS system and removing the power steering to its own system using the Pentossin fluid vs tapping off the brake system reservoir. Also the bias on the turbo is quite different with the 28mm x 2 rear piston size. Like I said just a guess.
Hi Guys,
I also have the interlock and brake lights come on.
So far, I replaced the R51 relay, but the warning lights still come on.
Would it make sense to replace the relays on the pump itself?
Thanks for any suggestions.
Q
What model 993 do you have?
Other than the warning lights coming on, are there any issues with the actual brakes?
My booster failure resulted in no braking assistance!
So the brake pedal went rock hard and I had to really stamp on the pedal to slow the car down... Scary.
Do you know anyone with a diagnostic tester as I believe you can test cycle the ABS to check if the different channels are working?
The brakes of my 964 C4 are fine. It seems the pump takes a little longer to do its work before I start and when I use the brakes prior to when this process is done, the Interlock and Brake warning lights come on.
They randomly go off and on, while I drive...I replaced the R51 relay thus far, but this didn't change much.
It could be the accumulator. Mine was losing enough pressure overnight, it would beep for about 10 seconds at start-up. Ended up being a tired accumulator (or bomb, as some say). Changed it and no more beeping.
The brakes of my 964 C4 are fine. It seems the pump takes a little longer to do its work before I start and when I use the brakes prior to when this process is done, the Interlock and Brake warning lights come on.
They randomly go off and on, while I drive...I replaced the R51 relay thus far, but this didn't change much.
During most of my ownership of my C4 the pump used to take a while to get up to pressure.
If I was impatient and started the car before the pump switched itself off, I'd get the warning lights come up on the dash as I drove off.
It's definitely better since replacing the booster, as it came with a new pressure switch too.
So yours may be pressure related as suggested by 968norway...
My 964 C4 ABS booster pump has died on me, pic below is the part in question, for illustration purposes.
No stock in the UK or EU and they're on back order with the Porsche factory in Germany until the beginning of August.
Don't even know if they'll be available then, that's just the date for an update...
So I've been looking at used parts, as I'd like the 964 back on the road ASAP.
I also looked at rebuilds, but that's for a different thread as there is plenty of posts covering that.
The 964 part has been superseded by a 993 part number, see below.
ABS booster pump part# 96435590101 superseded by 99335595302 listed for 964: C4/RS/Turbo-look 993: C4/C4S/RS
ABS booster pump part# 99335595350 superseded by 99335595351 listed for 964: none993: Turbo-look/Turbo
I'm trying to find out exactly what the difference is between the two current part numbers 99335595302 and 99335595351
As the 993 Turbo is 4WD and so are the 964 C4 nd 993 C4 (obviously).
Can I use the 993 Turbo ABS booster pump on my 964 C4????
I've read elsewhere on Rennlist that there is a difference in the hydraulic assistance boost ratio.
964: C4/Turbo 993: C4/C4S/Turbo all utilize the hydraulic brake booster with a power boost ratio of 4.8 964: RS/Cup/RS3.8/RSR 993: RS/RSR/GT2 all utilize the hydraulic brake booster with a power boost ratio of 3.6 964 C2 as a comparison the vacuum assisted brake booster ratio is 3.0
Apparently the 3.6 ratio is the sweet spot, but the 4.8 lists both the 964 C4 and the 993 Turbo, so this can't be the only difference or someone has the details wrong
Can anyone shed any light on this please...
Hi George,
You have an interesting question. I have a 993 Turbo here in my shop at the moment with a burnt out pump motor. I also have a 993RS and a failed pump from a 964 Carrera 4.
As we know, the C4 and RS have the same pumps and the Turbo pump is particular to that car.
I've pulled both pumps apart as far as practical and there is no differences that can be seen. The brake pump switches are all the same, the switching and operating pressures are the same. I'm convinced the pumps are the same.
The next thing I am going to try is fitting the RS pump into the Turbo to confirm.
I'm sure the booster ratios you speak of are in the booster part of the master cylinder, not the pump itself.
Neither pump is available from Porsche at the moment and there is no ETA....
Best,
Darren
Hi George,
You have an interesting question. I have a 993 Turbo here in my shop at the moment with a burnt out pump motor. I also have a 993RS and a failed pump from a 964 Carrera 4.
As we know, the C4 and RS have the same pumps and the Turbo pump is particular to that car.
I've pulled both pumps apart as far as practical and there is no differences that can be seen. The brake pump switches are all the same, the switching and operating pressures are the same. I'm convinced the pumps are the same.
The next thing I am going to try is fitting the RS pump into the Turbo to confirm.
I'm sure the booster ratios you speak of are in the booster part of the master cylinder, not the pump itself.
Neither pump is available from Porsche at the moment and there is no ETA....
Best,
Darren
Cool, I look forward to hearing your findings...
If you do need a booster pump, check out ECS Tuning in the US as they had stock.
Cheaper that Porsche too...
06-27-2023, 02:53 PM
ABS Booster Pump differences...
if dropping the ratio to 3.6 would not the ECU need 'updating' should it become confused from a different booster pump output pressure? Out of interest where did you read that 3.6 was the sweet spot?
