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 > 911 / 930 Turbo & Super Charging Forum


Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Registered User
 
proffighter's Avatar
 
Join Date: Aug 2007
Location: Switzerland
Posts: 2,185
Garage
930 Turbo brake problem

Hello to all

This is my first ever thread here, although I am member for more than a year (yes, shame on me)

So here is my problem:
Because I made a nearly race car (for street use), I relocated the master cylinder from top down to the pedal cluster, similar to old non boosted cars. I used the same cylinder (23.8mm as far as i know) that was fitted before.
Now, after one year of use, I feel like the performance is not that good. Brake feeling is very stiff, what I like. Until moderate speed, maybe 60km/h, it's OK, Pedal force needed is acceptable, even brake could be more agressive at beginning. But when I push more, performence does not increase much. At higher speed, it's driveable, but far away from that, what I exspect. Then I changed pads to Pagid oranges, slightly better, but still poor performance.
So my suspicion is, that the leverage of the pedal actuation is suboptimal. When I compare my selfmade version to pics i've found, it looks a bit different. But I can't check, because I haven't found some measures of the old pedal geometry. Here are some pics of mine



I have allready searched this forum for a solution, but I looks, like everyone, who remove the booster, use bias cylinder and left located at OEM position. On the website of VCI they offer a mercedes cylinder for non boosted cars, but to my question about the difference of the cylinder, they answered me, one is for boosted cars, how helpful
If someone of you know some solutions, please let me know. Of course you can ask me for more pics or details to my car.

Here is one from 2006, not current, but it looks allmost same today
Old 03-04-2009, 11:28 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #1 (permalink)
Registered User
 
Join Date: Dec 2001
Location: MA USA
Posts: 2,938
From your pics it looks like your master pivot is closer than the factory one for the boosted setup. Which would require more pedal pressure for the same brake pressure. So I would move the pivot outward more than the factory one and see if that helps.
__________________
Dean
911 SC turbo, 3.0L 930 motor, G50, 930 brakes, DTA EFI, 352 RWHP DynoDynamic dyno,
Old 03-05-2009, 04:47 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #2 (permalink)
Registered User
 
proffighter's Avatar
 
Join Date: Aug 2007
Location: Switzerland
Posts: 2,185
Garage
Thank you Dean.
To be more accurate, do you mean (concerning first pic), upwards or to the left? The pedal is not at same position on the pic than installed in car. When it's adjusted, the uniball center is allmost in right-angled to pivot of pedal to cylinder. Isn't the ratio best at this postition?
By the way, the reason for this position I choosed, was simply that the hole was allready there

So, where do you think the pivot should be exactly?

That's how I had adjusted



Old 03-05-2009, 06:26 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #3 (permalink)
OFF THE BOOST PIPE NOW...
 
A930Rocket's Avatar
 
Join Date: Oct 2003
Location: Mount Pleasant, South Carolina
Posts: 7,904
While Pagid oranges are a faily good pad for the track, it might be too much for the street, requiring heat to be effective. I'd try a pad that is more suitable for the street.

I know I lock up my Pagid blacks on the street until there is a lot heat in them, but at the track they work like a charm.

As mentioned above, your pedal geometry might be off as well.
Old 03-05-2009, 07:18 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #4 (permalink)
Registered User
 
Join Date: Dec 2001
Location: MA USA
Posts: 2,938
Measure the distance from the shaft pivot to the stock brake pivot. Then see what your hole measures. I would then increase the distance by say 10 mm. In other words I would fill your present hole and make a new hole a little more vertical of your present hole.

I agree that for the street I would use OE pads.
__________________
Dean
911 SC turbo, 3.0L 930 motor, G50, 930 brakes, DTA EFI, 352 RWHP DynoDynamic dyno,
Old 03-05-2009, 07:34 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #5 (permalink)
Registered User
 
proffighter's Avatar
 
Join Date: Aug 2007
Location: Switzerland
Posts: 2,185
Garage
Thank you for advices

Does anyone know the difference between the so called Mercedes M/C and the stock one, 23mm are 23mm, so what's the matter? Maybe other length for easier installing...?

Has one of you pics/measures of the older brake pedal (non-boosted M/C), best side view, so I can compare the pedals to determine optimum ratio

Regarding the pagid oranges, I felt they have better performance even cold than OEM, but thanks for any suggestion. I am 99% certain, that the ration of pedal is the key to my request

P.S. It's very nice to be part of this helpful forum
__________________
Roland

930 Turbo '81 Too many modifications to list
Old 03-05-2009, 10:35 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #6 (permalink)
 
Registered User
 
Join Date: Dec 2001
Location: MA USA
Posts: 2,938
I would post your request for a pic on the regular 911 forum. Do you have any junk yards around your area with 911's. You could go and measure one yourself.

Good luck
__________________
Dean
911 SC turbo, 3.0L 930 motor, G50, 930 brakes, DTA EFI, 352 RWHP DynoDynamic dyno,
Old 03-06-2009, 03:35 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #7 (permalink)
MEMBER # 930
 
waynesco1's Avatar
 
Join Date: Dec 2007
Location: Olympia Wa
Posts: 347
Safety Wire your hardware /
__________________
MEMBER # 930
Old 03-06-2009, 04:59 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #8 (permalink)
Registered User
 
proffighter's Avatar
 
Join Date: Aug 2007
Location: Switzerland
Posts: 2,185
Garage
@ Waynesco

What do you mean I should safe? (Sorry for asking, my english is not that good)?

@ Dean

That's a good Idea
__________________
Roland

930 Turbo '81 Too many modifications to list
Old 03-06-2009, 05:31 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #9 (permalink)
Moderator
 
Bill Verburg's Avatar
 
Join Date: Dec 2000
Posts: 23,473
Garage
The ends where the m/c bolts up are different and incompatible between boosted and non- boosted m/c

There are 2 boosted m/c used on all 911 from '77-89, 20.6mm for normal cars and 23.8 for 930s. These 2 m/c's are interchangeable.

there are 2 master cylinders used on all 911 from '69-77, 19.05 used on most and a very rare 20.6 that was used for half a year but hasn't been available in decades. There is also another ATE m/c sometimes called the Mercedes Benz truck m/c that is 23.8mm. All three of these are interchangeable.

W/ 930 brakes you want a 23.8mm m/c. You will have to expect much higher pedal effort when going from a boosted system to a non boosted system.


The mechanical advantage in the pedals is part of the boost, From memory the old non boosted setup had a mechanical advantage of ~4:1(but I'd need to look that up, I can't now because I'm using a secondary laptop) You can measure the arms on your setup to determine the mechanical boost that it has.

Pads also can be an issue, some have more initial bite than others and street pads will bite better than track pads when they are cold. I do not like Pagid Orange at all, though I don't think that is your issue. I used them for a while and felt that cold bite was acceptable. You might try a performance street pad like Pagid blue
__________________
Bill Verburg
'76 Carrera 3.6RS(nee C3/hotrod), '95 993RS/CS(clone)
| Pelican Home |Rennlist Wheels |Rennlist Brakes |
Old 03-06-2009, 06:28 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #10 (permalink)
Moderator
 
Bill Verburg's Avatar
 
Join Date: Dec 2000
Posts: 23,473
Garage
Boosted mount


Unboosted mount
__________________
Bill Verburg
'76 Carrera 3.6RS(nee C3/hotrod), '95 993RS/CS(clone)
| Pelican Home |Rennlist Wheels |Rennlist Brakes |
Old 03-11-2009, 08:21 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #11 (permalink)
Registered User
 
proffighter's Avatar
 
Join Date: Aug 2007
Location: Switzerland
Posts: 2,185
Garage
Here how I fit the m/c:



__________________
Roland

930 Turbo '81 Too many modifications to list
Old 03-11-2009, 09:26 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #12 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 09:43 PM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, 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.