 Brakes don't Bite |
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| bkrantz |
 Sep 1 2022, 08:16 PM
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#1
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914 Guru  Group: Members Posts: 8,170 Joined: 3-August 19 From: SW Colorado Member No.: 23,343 Region Association: Rocky Mountains 
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As part of my rebuild I completely replaced the brake system:
calipers and rear pressure valve rebuilt by PMB new ATE 19mm master cylinder new hard and flex lines new disks and Porterfield R4-S pads I went through many (many!) episodes of bleeding, with different methods. The pedal feels very firm from the first push, and does not pump up. Rear clearance is set at .004". I went through the PMB bedding process, and have driven around a bit. But the braking force seems weak. When I get on the brake pedal, I do not feel any "bite". Another 914 friend drove the car and also agrees. Any suggestions? |
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Replies
| Montreal914 |
Sep 5 2022, 09:12 PM
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Senior Member Group: Members Posts: 1,725 Joined: 8-August 10 From: Claremont, CA Member No.: 12,023 Region Association: Southern California
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Mentioned before but the stock system was designed with a 17mm MC. The 19mm one is used on the 914-6 which has 48mm front pistons instead of the stock /4 42mm. In the back, the pistons are 38 for the 914-6 vs. 33mm for the /4. This is a pretty big overall surface difference!
Being that our beloved 914s aren't assisted on the brakes, I would think switching to 19mm while keeping the stock calipers must make the pedal feel pretty scary. (IMG:style_emoticons/default/sad.gif) |
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Posts in this topic
bkrantz Brakes don't Bite Sep 1 2022, 08:16 PM
Superhawk996 Brake feel is highly subjective.
The obvious thi... Sep 1 2022, 08:51 PM mgphoto 19mm master cylinder, push the pedal harder, they ... Sep 1 2022, 09:54 PM barnfind9141972 I did the same thing and also couldn’t get much ... Sep 1 2022, 10:27 PM Mikey914 The system is notorious for holding bubbles. You w... Sep 1 2022, 11:07 PM ChrisFoley
As part of my rebuild I completely replaced the b... Sep 2 2022, 07:55 AM
Superhawk996
Adjust the rear brake regulator to begin regulat... Sep 2 2022, 09:24 AM
ChrisFoley
[quote name='ChrisFoley' post='3026647' date='Sep... Sep 2 2022, 10:58 AM Superhawk996
[quote name='Superhawk996' post='3026665' date='S... Sep 2 2022, 11:17 AM Superhawk996
Add a master cylinder brace to prevent floorboar... Sep 2 2022, 09:28 AM JamesM
As part of my rebuild I completely replaced the b... Sep 2 2022, 09:27 AM Superhawk996
Can you lock the brakes up if you stand on them?
... Sep 2 2022, 09:31 AM jim_hoyland What MPH would the front lock-up test best be done... Sep 2 2022, 09:57 AM Superhawk996
What MPH would the front lock-up test best be don... Sep 2 2022, 10:06 AM emerygt350 I just went and tried Locking them up tonight (hav... Sep 2 2022, 06:32 PM bkrantz Thanks for all the replies.
Yes, I can lock up th... Sep 2 2022, 07:38 PM Superhawk996
But I still think I should feel more bite and urg... Sep 2 2022, 08:41 PM JamesM
Thanks for all the replies.
Yes, I can lock up t... Sep 3 2022, 12:44 AM Van B I love the motive pressure bleeder. I don’t kno... Sep 2 2022, 08:23 PM bbrock I have essentially the same setup as you and get r... Sep 2 2022, 08:26 PM iankarr It takes several bleeds to get air out of a totall... Sep 2 2022, 10:34 PM Geezer914 Pressure bleeding is the best way to bleed the Bra... Sep 3 2022, 05:20 AM jim_hoyland
Pressure bleeding is the best way to bleed the Br... Sep 3 2022, 06:23 AM gereed75 Different car but maybe a useful data point - I ha... Sep 3 2022, 09:51 AM Superhawk996
Not sure what type of compound the R4S is, but ... Sep 3 2022, 10:07 AM bbrock
FYI - get ready for things to get worse. Copper... Sep 3 2022, 11:12 AM 930cabman
FYI - get ready for things to get worse. Coppe... Sep 9 2022, 01:16 PM bbrock
Sounds as though the consensus is having the abil... Sep 9 2022, 03:16 PM Superhawk996
It was the early version of ABS @Superhawk995 :... Sep 9 2022, 04:47 PM PatMc
[quote name='bbrock' post='3026923' date='Sep 3 2... Sep 15 2022, 10:06 PM jim_hoyland What's a recommended for light daily driving ?... Sep 3 2022, 12:25 PM JamesM
What's a recommended for light daily driving ... Sep 3 2022, 12:49 PM bkrantz Thanks, again. I will try bedding again with some... Sep 3 2022, 08:09 PM michael7810
Thanks, again. I will try bedding again with som... Sep 4 2022, 06:36 AM ChrisFoley I used to sell KFP pads because I liked their perf... Sep 4 2022, 05:02 AM bkrantz I ordered a set of Textar OEM style pads for F and... Sep 5 2022, 07:57 PM jim_hoyland I just ordered the Pagids from PMB, Here’s the i... Sep 5 2022, 08:46 PM robkammer This is a thread I thought I would need to start. ... Sep 8 2022, 01:25 PM ChrisFoley
venting clearance of 3mm.
Hmm, what? Sep 8 2022, 03:17 PM Superhawk996
On my last spirited drive with lots of hard braki... Sep 8 2022, 03:50 PM robkammer Guys: Oops, not 3mm, .003". Clearance between... Sep 9 2022, 07:39 AM bbrock Hmm. I have PMB plated calipers that I rebuild my... Sep 9 2022, 08:12 AM robkammer Thanks All: Good comments all around. Still not su... Sep 9 2022, 01:14 PM bkrantz I replaced the pads with "stock" Textars... Sep 15 2022, 07:48 PM robkammer All: This is all great info. So, an update, last S... Sep 16 2022, 04:11 PM bbrock
All: This is all great info. So, an update, last ... Sep 16 2022, 06:41 PM Superhawk996
Going on two years and getting tired of screwing ... Sep 17 2022, 11:05 AM michael7810 For $35 you can try a set of Textar pads for ... Sep 16 2022, 04:25 PM ChrisFoley New caliper seals cause a long pedal which will pu... Sep 17 2022, 07:02 AM PatMc I would try a conventional bleeding method…one p... Sep 17 2022, 07:47 AM robkammer Thanks All! Have not checked the pedal box, bu... Sep 17 2022, 01:32 PM Literati914 Man this is frustrating, hate that you’ve not go... Sep 19 2022, 09:20 AM Superhawk996
Man this is frustrating, hate that you’ve not g... Sep 19 2022, 09:48 AM rfinegan Last week I rebuild all 4 calipers, Potterfield pa... Sep 19 2022, 10:08 AM scott_in_nh I very recently got around to installing the KFP 1... Sep 21 2022, 12:48 PM bbrock
I do notice they are getting better, but my quest... Sep 21 2022, 01:44 PM NARP74 The numbers are on the round barrel, mostly on the... Sep 21 2022, 01:59 PM NARP74 For the pedal box flex, I had someone press the pe... Sep 21 2022, 02:04 PM |
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