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GODOG
Samba Member
Joined: March 08, 2025
Posts: 4
Location: Canada
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 Posted: Sat Aug 02, 2025 11:59 am Post subject: 1972 and up front brakes |
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It would seem that my 1970 notch has the newer version front calipers and I'm having issues understanding what going on. They lock on and stay on until I crack the bleeders. Can someone tell me what the center pin in the piston bore does?
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 23193
Location: Oklahoma City
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| Posted: Sun Aug 03, 2025 6:52 am Post subject: Re: 1972 and up front brakes |
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Background.....the late type 3 uses the same rotor and caliper as the EARLY type 4 cars.
Putting aside the differences in pad thickness and caliper offset/spacing from early to late.....the biggest VISUAL difference is that early rotors do not have what is called a "hub-centric" cuff cast into the center of the rotor.
Here is the late rotor (not yours). Notice the ring around the center on the wheel side of the rotor.
https://www.autohausaz.com/pn/13660884-411407075B?...20QAvD_BwE
Now look at this one. This is the one you have.
https://www.autohausaz.com/pn/12872314-411407075?u...9EQAvD_BwE
The earlier rotors....yours....with NO "hub-centric" ring....were also thinner. Without the ring they also flexed more.
So, on hard cornering or high speed sweeper curves....the earlier rotor....yours....flexes and an sometimes squeel, but has a habit of cocking the pistons slightly in the bores. Over time it can cause leakage and wear.
The pins and the little clutch in the back of the piston is designed to keep the pistons straight in the bore. Ray |
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Dfasty
Samba Member
Joined: November 22, 2005
Posts: 544
Location: north bay,ca.
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| Posted: Sun Aug 03, 2025 8:25 am Post subject: Re: 1972 and up front brakes |
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The soft lines to the front calipers are probably collapsing. If they’re over 10 years old they should be replaced. They swell from the inside and act like a one way valve. Which is your problem.
_________________
70 fastback automatic 06 invader |
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GODOG
Samba Member
Joined: March 08, 2025
Posts: 4
Location: Canada
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| Posted: Sun Aug 03, 2025 10:39 am Post subject: Re: 1972 and up front brakes |
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So....to fix my issue, I replace the rotors, hoses, calipers....
Is there any standard measurements for the caliper bore ?
I'm kinda curious to see how worn the bores actually are... |
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Bobnotch
Samba Member
Joined: July 06, 2003
Posts: 23418
Location: Kimball, Mi
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| Posted: Sun Aug 03, 2025 1:42 pm Post subject: Re: 1972 and up front brakes |
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| Dfasty wrote: |
| The soft lines to the front calipers are probably collapsing. If they’re over 10 years old they should be replaced. They swell from the inside and act like a one way valve. Which is your problem. |
Yes, I dealt with that back in the early 90's when the internet wasn't around. My 70 Fastback had new rotors (with the hub centric ring that Ray says shouldn't be there on the 66-early 71 rotors), and new calipers. I replaced the master cylinder first thinking there was something in it that causing a problem (according to Bentley), then I replaced the hoses which had internally collapsed. Since then, whenever I do a brake job on a type 3, I replace the hoses right after having the calipers rebuilt or replaced (done at the same time, since I have the system open). Replacing the hoses allows the fluid to flow BOTH ways in the system.
OP, your first clue about opening the bleeders is telling you the hoses are bad. They aren't flowing fluid back to the master cylinder. Also, your brake pistons should be 42mm in diameter (Ghia calipers are 40mm, and are commonly sold as type 3 replacements). These don't really wear over time, but the seals can wear. Just something to think about. As for the pin, it was to help keep the piston from cocking in the bore when the car was in a turn, putting a load on the rotor (flexing). As time went on, that pin got eliminated.
I hope this helps.
_________________
Bob 65 Notch S with Sunroof
71 Notch ...aka Krunchy; build pics here;
http://www.thesamba.com/vw/forum/viewtopic.php?t=249390 -been busy working
64 T-34 Ghia...aka Wolfie, under construction... http://www.thesamba.com/vw/forum/viewtopic.php?t=412120
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| Tram wrote: |
| People keep confusing "restored" and "restroyed". |
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GODOG
Samba Member
Joined: March 08, 2025
Posts: 4
Location: Canada
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| Posted: Wed Aug 06, 2025 8:32 pm Post subject: Re: 1972 and up front brakes |
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Well.......I got some new hoses today. I put in some new quasi seals in the calipers, cleaned everything up, put a buff on my pistons and installed some new dust boots. After a quick bleeding session I now have brakes that work both on and off. No drag at all.
Thank you guys for helping me with the information.
Much appreciated |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 23193
Location: Oklahoma City
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| Posted: Fri Aug 08, 2025 5:37 am Post subject: Re: 1972 and up front brakes |
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| GODOG wrote: |
Well.......I got some new hoses today. I put in some new quasi seals in the calipers, cleaned everything up, put a buff on my pistons and installed some new dust boots. After a quick bleeding session I now have brakes that work both on and off. No drag at all.
Thank you guys for helping me with the information.
Much appreciated |
What are "Quasi" seals?
Ray |
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GODOG
Samba Member
Joined: March 08, 2025
Posts: 4
Location: Canada
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| Posted: Fri Aug 08, 2025 11:23 am Post subject: Re: 1972 and up front brakes |
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| Quasi seals is a loose term used in hydraulics for the square cross section o rings used in a "one direction" rod seal. |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 23193
Location: Oklahoma City
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| Posted: Fri Aug 08, 2025 12:46 pm Post subject: Re: 1972 and up front brakes |
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| GODOG wrote: |
| Quasi seals is a loose term used in hydraulics for the square cross section o rings used in a "one direction" rod seal. |
Ah....I think you mean "quad seal", also called an "X" ring.
The square profile o-rings in the caliper are usually called square profile or "lathe-cut" rings. Many o-ring manufacturers recommend that whenever possible, replace square profile rings with quad-rings/q-rings/X-rings as they are more aggressive at sealing than a square profile.
Ray |
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