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!tom · Posted: Wed Jun 15, 2011 12:25 pm Post subject: 5-lug question

I've got a question regarding the rear brake callipers on a 5-lug setup.

The callipers end up displacing towards the outside of the car as the brakes wear, as it is a floating calliper design. This means that as the car is used, the brake line that attaches to the calliper must flex.

On the bits that I have, it's a hardline in this location.

It seems to me that this should be a flex line.

In everything I've seen about this, including PET, there is a hardline in this location.

What's up with this? How is the brake line bent in order to minimize the lack of flexibility as it applies to brake drag, and fatigue issues? Are there any good pictures of a stock brake line shape/routing in this location?
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78 924 NA
5-lug

Ozzie · Posted: Wed Jun 15, 2011 1:57 pm Post subject:

One side of the caliper is fixed.
This should be the side the piston and brake line is on.
The other side floats.
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Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

!tom · Posted: Wed Jun 15, 2011 3:38 pm Post subject:

This isn't how it appears to me that it works.

The piece with the arrow is bolted directly to the suspension arm. It has a big hole in the middle through which the calliper piston protrudes. It also has the pins (part 6) on which the pads ride to keep them in position relative to the rotor (part 1).

This piece that the arrow is pointing to is the calliper cylinder and bracket which holds both pads. As the outer pad wears, the entire bracket shifts towards the centerline of the car. The brake line is attached to the calliper cylinder, thus it must flex as the outer pad wears.

Too bad there isn't a better picture.
Edit: Fixed pictures
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78 924 NA
5-lug

Ozzie · Posted: Wed Jun 15, 2011 4:39 pm Post subject:

as both pads wear the piston takes up the difference on one side and the floating keeps the cylinder central to the hub. ,eg. no movement.
(as long as each pads wears at the same rate.)
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Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

!tom · Posted: Wed Jun 15, 2011 11:26 pm Post subject:

The piston works its way out to compensate for inner pad wear; what works its way in to compensate for outer pad wear?

On my callipers it's the floating calliper assembly that works its way inwards to compensate for outer pad wear, including the brake line.
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78 924 NA
5-lug

ptheskil · Joined: 03 Aug 2004 Posts: 128 Location: Essex, UK

Brockoli · Posted: Fri Jun 17, 2011 3:40 pm Post subject:

I just rebuilt my 5-lug brakes and the rear hard brake line is very long and I had no problem moving it around when it was disconnected to the caliper. I do not believe the hard line is attached or bolted down to prevent it from moving. I believe there will be sufficient movement so the brake line shouldnt break.
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'80 924 M471,Wideband O2, Full coilover susp,23/19 sways,Bilstiens,KLA Strut Brace,Roll Bar,Test Pipe,BBS RS, Willwood BBK

25% of a '87 944 Chumpcar http://straightpipe.ca/forums/showthread.php?t=2454

'79 924 Sebring Edition(Sitting)

edredas · Joined: 09 Dec 2004 Posts: 861 Location: Charlotte, NC

On my S there's a clip that holds the brake line up while allowing it to travel back and forth.
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'84 944 -White, Brown interior
'84 944 -Red, Automatic
'86 944 -Garnet, Fully loaded, Koni suspension
'87 924S -Red, 300hp 951 swap
'87 924S -Red, Project Car
'88 924S -Red, Daily Driver

!tom · Posted: Fri Jun 17, 2011 3:59 pm Post subject:

Thanks for the pic! I was wanting a picture so I knew how the hard line should run. A bend like what you show should allow easy calliper movement -- a straight shot from the back of the calliper would not.
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78 924 NA
5-lug

!tom · Posted: Sat Jun 25, 2011 6:29 am Post subject:

Can anyone confirm if the above pictured calliper is assembled properly?

I used the above picture as a guide for which pot goes on which side.

With my car's butt sky high and the suspension fully extended, it looks like the bleeders aren't at the top, but assembling the callipers so that the bleeder is inboard of the bracket (swapping the pot from the right side of the car into the calliper pictured) looks to me like it would put the bleeder at the top.

I'm in the assembly stage, and I'd rather sort this out now than after I get everything else put together.

Thanks!
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78 924 NA
5-lug

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

Bleeder to the rear is correct.
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Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

!tom · Posted: Thu Aug 11, 2011 1:44 am Post subject:

I haven't been driving my car much with the 5 lug brakes yet because I've been away and there are a couple issues.

One major issue is occasional pad knockback. The front bearings are correctly adjusted; I've traced the problem to the rear. The rear hard brake lines rub the inner fender, so much so that the caliper is pushed over releasing the brakes.

This with brand new pads too; as the pads wear, the caliper will work inwards, exacerbating the problem.

Is this a problem anyone else has? I was certainly not expecting this issue. I'm not sure if the solution should be to modify my existing brake lines, bend new ones, or whack the fender with a hammer.

It looks like the above picture, except the brake line hits the fender with the suspension loaded.

Tips? Thoughts?
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78 924 NA
5-lug

fiat22turbo · Joined: 18 Jan 2006 Posts: 4040 Location: Portland, OR

Your brake line isn't in the right spot then. Gently tweak it so that it clears the inner fender, just be careful you don't crimp the bend into the calipers. If you don't have the clips on the trailing arm to hold them in place, use zip ties and leave them a little loose to allow for some float.
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)

!tom · Posted: Tue Jun 04, 2013 3:00 pm Post subject:

An update, as this was an unexpected development with my 5-lug conversion.

I ended up bending the inner fender a little bit on each side for more clearance, and the brake lines are a bit mangled too. I have on my to-do list bending up new brake lines, but what's on the car now is sufficient.

Is the inner fender a different shape on the earlier shells?
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78 924 NA
5-lug

ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

It wouldn't surprise me if that were the case. What year is your shell? Can you get the rear end up in the air, and then take a pic of each of the inner fender wells? Then we can compare to the 78, 80, and 81 chassis I have at the shop.
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erstwhile owner of just about every 924 variant ever made