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951 brakes issues

Hello,
I have a VW 1303S onto which I want to install 951 brakes. I bought front spindles, rotors and Brembo calipers and a complete rear axle, which was disassembled. During the weekend I tried to put the rear axle together, and I got a problem: the calipers are hitting the rotors. It seems that there is a ~3mm mis-alignment. The rotors are correct (951 352 041 02), they came down from the same axle. Is there a spacer between the caliper and aluminum arm? I have read on one topic that somebody had a similar problem and somebody else asked if the 3mm spacers were put back into place. I added 2.5mm washers between the caliper and arm, now It does not hit anymore, but it seems 3mm would get everything right.

I have also read that the front strut mounting flange is different, thicker and the holes are at a different position? I can elongate one of the holes on the strut if it is so. Is the strut angle the same, or do I need to add more camber?

Now I also have the problem that I have 15" Cookie Cutters that hit the calipers, but the interference seems to be very small, I hope I can solve that with a 3-5mm wheel spacer. Or homologate bigger wheels, which is harder in my country (Romania).
Old 09-04-2017, 01:47 AM
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Quote:
Originally Posted by Tzepesh View Post
Hello,
I have a VW 1303S onto which I want to install 951 brakes. I bought front spindles, rotors and Brembo calipers and a complete rear axle, which was disassembled. During the weekend I tried to put the rear axle together, and I got a problem: the calipers are hitting the rotors. It seems that there is a ~3mm mis-alignment. The rotors are correct (951 352 041 02), they came down from the same axle. Is there a spacer between the caliper and aluminum arm? I have read on one topic that somebody had a similar problem and somebody else asked if the 3mm spacers were put back into place. I added 2.5mm washers between the caliper and arm, now It does not hit anymore, but it seems 3mm would get everything right.

I have also read that the front strut mounting flange is different, thicker and the holes are at a different position? I can elongate one of the holes on the strut if it is so. Is the strut angle the same, or do I need to add more camber?

Now I also have the problem that I have 15" Cookie Cutters that hit the calipers, but the interference seems to be very small, I hope I can solve that with a 3-5mm wheel spacer. Or homologate bigger wheels, which is harder in my country (Romania).
I can't say on your first question. You can look in the parts catalogue (PET). You need to know what year car your parts are from. Lots of components changed for the 1987 model year.

As for the strut mounting flange being different, to what are you comparing? They changed through the years and I've never memorized why and when.

As for the wheels, I don't know if spacers solve that issue. I can say that the early-offset 15"x7" Phonedials (951 part number) are the only factory 15" wheels to fit over the Brembo brakes. I think Jongbloed makes a 15" wheel that also clears the brakes.

If you happen to have Turbo S brakes (from the 928 S4), then 15" wheels do not fit. Only certain 16" wheels.

I would recommend you post your question in the main 924-44-68 forum here (it gets more views). Even better, post on Rennlist's 924-44-68 forum here: https://rennlist.com/forums/924-931-944-951-968-forum-70/ . They should know more about your first two questions.

Last edited by FrenchToast; 09-04-2017 at 02:40 PM..
Old 09-04-2017, 02:38 PM
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Well, I asked here because these brakes come from a 951, not from 924/944/928. They are not brakes from the S4.
Is there an online parts catalog?
I am comapring to normal 944 spindle, with sliding ATE brakes (this is what I have now on my car). I was refering to the spindle mount of the strut, not the top mounting flange.
For the wheels hitting the calipers, I have to make a trial with some shims and see how it goes. I just put the wheel on and it seems to be flush with the rotor, but it still touches a bit the caliper, this is why I think it will work.
Thanks for the suggestion on rennlist, I will also write there.
Old 09-04-2017, 11:17 PM
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Yes, there are spacer washers that go on the rear calipers on the late offset cars.

PET has the correct part from Por$che if you want, but matching thickness from a hardware store will work the same.

You can do what you mentioned for the fronts, but you have an early/late mismatch for your struts and spindles. Camber will be limited with this "fix" as well, as I recall.
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Old 09-05-2017, 05:05 AM
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I agree PET could have it, most probably PN 999 025 131 01. But I only got the vague information that the spacer is ~3mm. I need the real value, the shims from hradware store I used now just for testing are ~2.5mm and it seems that the caliper is not in the correct position, not more than 1mm. If I get the real info, I can make my own spacers, instead of making a 4$ order from abroad...
Old 09-05-2017, 05:27 AM
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Originally Posted by Tzepesh View Post
I agree PET could have it, most probably PN 999 025 131 01. But I only got the vague information that the spacer is ~3mm. I need the real value, the shims from hradware store I used now just for testing are ~2.5mm and it seems that the caliper is not in the correct position, not more than 1mm. If I get the real info, I can make my own spacers, instead of making a 4$ order from abroad...
The thickness of the shim is just enough to center the caliper over the rotor. The measurement and calculations are left as an exercise for the student.
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Old 09-05-2017, 08:16 AM
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I got a relpy from Rosepassion, the spacers are 3.5mm. I will order from them, because I also need 911 valve adjuster screws.
One more question that has been asked many times: what 15" wheels fit the 951 brakes? I have read many threads but I still do not have a sure info. It seems that phone dials are the only ones that would fit, but what ET, early 23mm or late 52.3mm? My cookies hit the calipers and only a wide spacer seems to solve the issue (I tried 5mm, more is needed). I don't want to homologate 17" wheels.
Old 09-10-2017, 11:19 PM
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Quote:
Originally Posted by Tzepesh View Post
One more question that has been asked many times: what 15" wheels fit the 951 brakes? I have read many threads but I still do not have a sure info. It seems that phone dials are the only ones that would fit, but what ET, early 23mm or late 52.3mm? My cookies hit the calipers and only a wide spacer seems to solve the issue (I tried 5mm, more is needed). I don't want to homologate 17" wheels.
You need early 15x7 Phonedials. Offset of 23. They must have the 951 part number (I think all 15x7 ET23 phones do, but not sure).

The only other wheel I know of that I may fit is the Jongbloed 15x8 (500 series). I'm not sure if anyone has tested it but the rep seemed to think they would clear.

I doubt 15x7 Fuchs would clear. Fuchs are not known for their ability to clear big brakes. But, it is possible. If originals don't fit but you really want Fuchs, there are several companies that make replicas. Sometimes they've been redesigned to provide more brake clearance. You would need to take measurements based on the hub surface and centerline, send them to the company and ask if they fit. Or ask someone with a 944 Turbo (with the same year hubs and spindles as you, they changed them) to take measurements.

Last edited by FrenchToast; 09-12-2017 at 01:22 PM..
Old 09-12-2017, 01:14 PM
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Thank you, this is the kind of info I needed. I am looking for stock 15" wheels, not aftermarket. Phone dials sound good, I do not like Fuchs. I'll look for 7x15" ET23, I'm sure I can find a set somewhere.
There was a topic I read some time ago, on wheel size and offset changes over the years for 944/951, but I can not find that topic again.

Last edited by Tzepesh; 09-12-2017 at 11:54 PM..
Old 09-12-2017, 11:47 PM
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Small update: 15" Phonies, ET23, PN 95136210400 do fit over the calipers, front and rear.
I will, however, try to fit my Cookies. On the back they are fitting right, on the front I can make them fit with 20mm spacers.
One more problem: I tried to remove the front rotor and it does not come out (rusty I think). It is the late version, rotor is held by the hub by two small Philips screws and I do not need to remove the hub to dis-assemble the rotor. Any tricks on how to get the rotor off, except pure force? I already soaked the interface in WD40.
Old 10-09-2017, 03:45 AM
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I soaked the rotor to hub interface in penetrating oil, applied some heat and some force and the rotor came out. However, it cracked near the two threaded holes used for pulling the rotor.*
Another question now: can I use the later front hubs, rotors and Brembo calipers on early spindles? This way I can use the stock struts. I also have a flip kit for tie rods installed in the ealy spindles, so I can use them in the VW Bug, and I wouldn't machine the late spindles if I can use the old ones.
Old 10-13-2017, 11:07 AM
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I am not sure what you are trying to do, but usually a production change like the turbo the suspension is built stronger to handle the added power and better braking. Trying to piece parts on an older model leaves a weak spot somewhere. struts on 87 on cars have a wider gap where the spindle bolts up because the spindle is stronger and the hub takes larger bearings. The left side is weaker because of the hole for the speedo cable. Racers with these early cars often broke the spindle. ask me how i know...A later car had electronic speedos with sensor on trans. Good luck, LA
Old 11-02-2017, 10:53 PM
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What cracked? The hub or the rotor? If the rotor, easy, toss it and get a new one. If the hub, then you can get a new hub. Should be plenty of used ones around, just ensure it is free of cracks and matches in part number.

If replacing just the hub, you probably want one off the same side. Further, I do not know if like some engine internals they should be matched (not mixed). The hub and spindle have worn accordingly over time, and installing a different, used hub could cause strange wear.

If this does matter, I would recommend getting a new hub (brand new from Porsche). It's probably cheaper to get an entire used spindle/hub assembly.

Quote:
Originally Posted by Tzepesh View Post
Another question now: can I use the later front hubs, rotors and Brembo calipers on early spindles? This way I can use the stock struts.
No. If the "early spindles" are from an '86 Turbo, the brakes would bolt on but that is all. The hubs and rotors are different.

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Originally Posted by acar24 View Post
The left side is weaker because of the hole for the speedo cable. Racers with these early cars often broke the spindle. ask me how i know...A later car had electronic speedos with sensor on trans. Good luck, LA
I think the hollow spindle is only on 944s up to 85.5. And likely all 924s.

Last edited by FrenchToast; 11-03-2017 at 11:49 PM..
Old 11-03-2017, 11:36 PM
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If you really want to use the later parts just have the spindles machined where they mount in the strut, it is a very beefy area anyway and I am sure it won't weaken anything there to take .5 mm off or whatever the diff is.
Old 11-04-2017, 08:46 AM
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wheel

The problem with wheels is usually the center hole isn't machined big enough to clear the larger grease cap/hub. If they work with spacers this is what usually is wrong, if you have a friendly machinist you could increase the back side of the center hole to clear if you are set on a wheel style.
Old 11-04-2017, 08:57 AM
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