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914World.com _ 914World Garage _ Rear Brake Caliper Removal

Posted by: zoomCat Jun 8 2005, 03:58 PM

Hi everybody!

I'm in the process of trying to resurrect my Sleeping Beauty from her slumber. She's been asleep for a few years. I've changed out the oil and gas and got her started; ran like crap but I figured I'd have to rebuild the carbs anyway.

I'm now trying to get the rear brake calipers off but I'm having some difficulty. This is kinda embarassing, since 1) all the descriptions I've found make it sound pretty simple, and 2) I've done it before.

So I start by taking my 11mm flare wrench and go to remove the brake line from the caliper and I can't get the wrench onto the flare nut. Huh? Aft of the hard line the control arm is in the way, and forward of the line is a boss on the caliper itself as shown below (i hope).

It would seem that I have to split the hard line from the flexible line at the control arm pivot. It that correct?

Oh, and this is a factory /6, does that matter?

(i was going to post some pictures of her when i get her out of the garage and cleaned up a bit, but i thought i'd get some brakes working first....)

Attached image(s)

Posted by: skline Jun 8 2005, 04:14 PM

Just remove the caliper and then remove the hard line. I would also consider cutting the lines and replacing them anyway.

Posted by: ! Jun 8 2005, 04:50 PM

If those are stock 914/6 calipers....they are very rare. The Ferrari used them and the limited amopunt 914/6s...if you want to sell them, they will finance an upgrade for BOTH the front AND rear brakes.

Agree with Scott, pull them off and cut the lines, soak the nuts with a penetrant and remove them after a day or so. Get new ruuber and steel lines.

Posted by: zoomCat Jun 8 2005, 05:24 PM

I'm not entirely sure what the caliper in question actually is.

The car came with non-stock calipers from the PO, some 911 front setup with a vented disk but no parking brake. They started to stick, and I got a used pair from a vendor in the early/mid 90's that looked good, but had single bleeders only on the bottom. Volvo? Ferrari? Don't know. I might look into tapping another bleeder hole in them and using them in Some Future Project.

I then found a used set of what were purported to be actual /6 calipers that had been widened, and that's what I'm looking to put onto this car. Hopefully, I'll get vented rotors and a parking brake. This car has a 2.7 in it, so vented rotors are probably a good idea.

Looking at the purported /6 calipers I have they appear to have the same boss that's my problem above, and they were shipped to me with the hardlines still attached. I guess they come out by splitting them at the union with the flex line.

My confusion comes from the various threads and tech articles that say pretty consistently to remove the hard line from the caliper first before removing the caliper from the control arm. I guess my concern then is that I still don't have 914 calipers, either /4 or /6.

The good news is that the brake line broke free at the union without any struggle. Now I just gotta go buy a couple of quarts of brake fluid, suddenly realizing I don't have enough in house to handle this.

So, I guess the question I have now if I've got one or two pairs of calipers that won't work?

Posted by: SirAndy Jun 8 2005, 05:41 PM

QUOTE (zoomCat @ Jun 8 2005, 04:24 PM)
I got a used pair from a vendor in the early/mid 90's that looked good, but had single bleeders only on the bottom.

bottom? how are you supposed to get the air out then?

Andy

Posted by: ArtechnikA Jun 8 2005, 06:29 PM

we're gonna need better pictures ...

Posted by: zoomCat Jun 9 2005, 12:59 PM

OK, more pictures...

First is a pic of a caliper sold to me in the early 90's purported to be a used /6 caliper. I'm showing the inboard side of the passenger side caliper, with the bleeder highlighted. What I find interesting is that the hydraulic line and the bleeder are on opposite ends, which would put the bleeder on the bottom as installed in a 914.

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Posted by: zoomCat Jun 9 2005, 01:05 PM

And here's another, this one showing a comparison between the previous caliper and a caliper that was sold to me as a used /6 caliper. Note the highlighted bleeders.

Attached image(s)

Posted by: Eric_Shea Jun 9 2005, 01:08 PM

I hope you didn't cut the line...

QUOTE
I would also consider cutting the lines and replacing them anyway.

QUOTE
Agree with Scott, pull them off and cut the lines,

Those lines are NLA

The Ferrari caliper has the bleeder on the bottom. They will need to be retro-fitted with "dual" bleeders like the later 914-4 calipers.

The one's in the picture appear to be 914-6 calipers. They do not have the raised spine on the back.

Posted by: ArtechnikA Jun 9 2005, 01:09 PM

i have some 914.6 calipers in a box at home (doesn't everyone?) and i'll check 'em out for comparison purposes...

the widened (vented disk) caliper is out on the workbench, the stockers are in a box.
film at 11...

(well - digital pictures somewhere around 2100 EDT...)

Posted by: Eric_Shea Jun 9 2005, 01:11 PM

Here's a picture of a pair of factory 914-6/GT calipers. This shows the proper relationship of the bleeder and arm.

Attached image(s)

Posted by: zoomCat Jun 9 2005, 01:13 PM

Here's a shot of the width between some bosses that the disk fits between. Its also a shot of my latest manicure and my fancy-schmancy Harbor Frieght digital calipers.

Is this a widened caliper for a vented rotor, or will it need a solid rotor?

Attached image(s)

Posted by: ClayPerrine Jun 9 2005, 01:16 PM

I sold Rusty my factory /6 calipers. But I do remember that the bleeders are on top. Do the calipers have spacers for vented rotors already installed? If the bleeders are on the bottom, and they have spacers for vented rotors, then these are Ferrari 308 calipers. Don't worry, the 308 calipers and the 914 /6 calipers are identical other than the location of the bleeder and the spacer between the caliper halves. The Ferrari guys will buy 914 /6 calipers for their cars if they can find them.

Posted by: Eric_Shea Jun 9 2005, 01:20 PM

Now... back to your question.

QUOTE
the question I have now if I've got one or two pairs of calipers that won't work?

They'll "all" work. One pair with less effort than the other. If you need to use the other it would still be less expensive to install the second bleeder than it would be to buy another pair but seeing as how you have a second pair...

So, the rusted one looks to be from a Ferrari. The silverish one is from a -6. To install vented rotors with the -6 caliper you will need to install 10mm factory spacers, get custom pad pins (10mm longer in the center) and custom 5mm rotor spacers made. The Ferrari calipers should have had the spacers in them. My guess is someone took them out. (unless you're currently sitting on vented rotors.

We just finished a set for Tom Krueger and the total was $527.70 ($245.00 of which was a standard -6 rebuild) The ones pictured above are off Tony Samojens GT.

Posted by: Eric_Shea Jun 9 2005, 01:21 PM

QUOTE
Is this a widened caliper for a vented rotor, or will it need a solid rotor?

That's for vented. It has the 10mm spacers in it.

Posted by: zoomCat Jun 9 2005, 01:35 PM

It looks like both sets I have have the 10 mm spacer already installed.

So it looks like the guy who sold me the used /6 calipers (forget his name, it was a while ago...) spoke the truth. I've also got some new vented rotors lying about, now I just need to find/fabricate spacers. Is my memory correct that it should be 5mm?

Is it too naive to think I could just find some flat stock, take a hack saw and my drill press....

Oh, i still find myself looking back at the pics of your handiwork Eric. That stuff is gorgeous.

Posted by: Eric_Shea Jun 9 2005, 01:41 PM

Thanks! Your's can look like that

QUOTE
Is my memory correct that it should be 5mm?

Is it too naive to think I could just find some flat stock, take a hack saw and my drill press....

Yes.

and... yes

Actually, depending on how handy you are with the old hack saw and drill press... maybe. You need to space out the rotor because, as you already know, there's not much room to move the caliper back.

Posted by: zoomCat Jun 9 2005, 02:28 PM

So looking around the usual sources I find a lot of wheel spacers, but no hub spacers. Is there something I'm overlooking or are these things that unusual?

Or can I just use wheel spacers, just stick them behind the hub? I'd expect the tolerances to be a bit tighter for hub spacers....

So, anybody got any favorite source?

Posted by: ArtechnikA Jun 9 2005, 02:37 PM

i'll go measure my spacers, but IIRC, they're 3mm (near 'nuff - 1/8"). i don't think i ever actually measured the thickness of the caliper spacers themselves - i just had the work done and bolted it all up when i got the parts back. and they all worked great...

since the face of the hub is flat, and the inside face of the 911 disk hat is flat, almost any reasonably hard alloy of aluminum should work just fine. you have the full clamping force of 5 lugs keeping things tight.

Posted by: Eric_Shea Jun 9 2005, 04:33 PM

QUOTE
Is there something I'm overlooking or are these things that unusual?

Or can I just use wheel spacers, just stick them behind the hub? I'd expect the tolerances to be a bit tighter for hub spacers....

These things are unusual. Custom made at this point.

Wheel spacers are too large to fit "under" the rotor but you could turn them down if you find them in the proper size.

Posted by: ArtechnikA Jun 10 2005, 09:47 AM

back from the garage, dial caliper in hand...

the spacer in my caliper is 0.396" (10mm).
the hub spacer is 0.125" aluminum (i.e. - 1/8")

Posted by: zoomCat Jun 10 2005, 11:07 AM

By my thinking, a 3mm spacer would cause the outboard piston to extend 4mm farther than the inboard piston, but no more than 2mm farther than it normaly would. You'd loose 2mm of use when the inboard pad wore out first, so the outboard piston would never see more than 2mm or extra travel. I think.

If it works for Mr. Herzog, it would probably get me around the block safely....

So, is 5mm or 3mm enough to require longer studs? Or switching to steel nuts from the alloy? Actually, if limiting the thickness of the spacer to 3mm would allow the use of the stock studs that might be sufficient reason to forgo the correct symmetry...

Anybody got a source for hub spacers of either size (3 or 5mm)? Or a couple lying around?

Posted by: ArtechnikA Jun 10 2005, 11:31 AM

QUOTE (zoomCat @ Jun 10 2005, 01:07 PM)
You'd loose 2mm of use when the inboard pad wore out first, so the outboard piston would never see more than 2mm or extra travel.

If it works for Mr. Herzog, it would probably get me around the block safely....

So, is 5mm or 3mm enough to require longer studs? Or switching to steel nuts from the alloy?

2mm of rear brake pad is a LOT in any street car, and i don't think anyone preparing a track car would let it go anywhere near that point. if that's my cost, it's one i'm prepared to pay.

i had no qualms (or any lack of braking) at Willow Springs, Holtville (notoriously hard on brakes) and Riverside.

on my car, with Mahle alloys, the stock studs were close to too short. Fuchs might be a little thinner in the cup, but i don't have any here to check. IMO slightly longer studs are a good idea, because you'd have more choices on spacers, and no track car should use alloy nuts anyway.

slightly longer studs aren't much more expensive than the stockers...

1/8" aluminum plate should be readily available and none of the dimensions is especially critical. you can drill "big enough" holes for the studs with a drill press, the outside circle with a saber saw, and just a bit of time with a dogleg deburring tool should have you in the ball game quickly.