Rear Caliper Install Rotor Clearance Issue, 914-6 Options

[DennisV]

I have newly restored calipers from PMB. They look great. Front went on no problem. The rear have been a real bear. I've tried both sides and I can't get reasonable clearance between the caliper (no pads) and rotor. I wonder if I have the alignment of parts wrong. (IMG:style_emoticons/default/confused24.gif)

My understanding, working from outside in, is:
Trailing arm mount <- cover plate bracket <- caliper <- bolt
Meaning the cover plate bracket is sandwiched between the caliper and trailing arm. Do I have that right? I tried the reverse as well and it still didn't line up well. (IMG:style_emoticons/default/blink.gif)


Not sure what I'm doing wrong... Damn you Ian Karr and your videos that make this look so easy. (IMG:style_emoticons/default/biggrin.gif)

P.S. As you can see in the photo, the rotors are not vented so that should not be adding to any clearance issues.

[rgalla9146]

Is the stub axle tightened in the wheel bearing /hub ?
Is the rotor tight on the hub ?
The order of the caliper mount looks right.

[sixnotfour]

what's the PN on rotor ?

[DennisV]

what's the PN on rotor ?

I ordered 901-352-401-18 from PMB. They are Sebro.

If you're asking what number is stamped or engraved on the rotor itself, I didn't see one. I wasn't really looking for that though. Wouldn't hurt to check when I get back to the car.

[DennisV]

Is the stub axle tightened in the wheel bearing /hub ?
Is the rotor tight on the hub ?
The order of the caliper mount looks right.

Stub axles are not installed yet, so I literally have some wiggle room.

The rotor is tight on the hub. 2 retaining screws installed. Both sides.

[porschetub]

Is the stub axle tightened in the wheel bearing /hub ?
Is the rotor tight on the hub ?
The order of the caliper mount looks right.

Stub axles are not installed yet, so I literally have some wiggle room.

The rotor is tight on the hub. 2 retaining screws installed. Both sides.

,
Your order is off on assembly and is real important ,you won't address your issue unless its all back together as things will change when final torque of the axle nut is completed..250ft/lbs if I remember right ,cheers .

[mate914]

Axle has to be installed.
Matt

[nditiz1]

Does the axle need to be installed???

The bearing sits inside the carrier. The hub is pressed into the bearing. It seemed to me OP was only replacing the caliper and the rotor.

Can you post a pic with the caliper installed? I just went through this with my conversion. New hubs, bearings, rotors, calipers. I do not have clearance issues, maybe 2mm on each side of the caliper face to the rotor face.

[Superhawk996]

Warning. - do not roll the car around without those stubs installed. It will damage the wheel bearings. Suspect that hasn’t happend because the car is still on the hoist but don’t do that if the temptation arises.

[davep]

Stub axles are not installed yet, so I literally have some wiggle room.
The rotor is tight on the hub. 2 retaining screws installed. Both sides.

Therein lies the problem. The interface between the rotor and hub has to be perfectly clean in order that the rotor runs true. You may even have to clock it to find the best balance. The retaining screws just keep it from falling off while working on the assembly; they are not enough to ensure the fit is sufficiently tight. You need the wheel nuts torqued down to be certain. You also have to have the stub axle in place and torqued to spec to be sure the assembly will be fitted correctly. Only then should you install the caliper.

[DennisV]

Your order is off on assembly and is real important ,you won't address your issue unless its all back together as things will change when final torque of the axle nut is completed..250ft/lbs if I remember right ,cheers .

Hrmm. OK. I am blending topics a bit, but here goes. I stripped the car of engine, suspension, brakes, and fuel components. I did a post about order of assembly operations and the most popular path seemed to be installing the engine before stub axles for better clearance.

So long story short, I left the stub axles off as I haven't installed the engine yet. So I have to do the engine and stub axles before I can complete the brakes? (IMG:style_emoticons/default/confused24.gif) I would have thought the rotor would wobble in the caliper, but not prevent it from being installed.

The car is on jack stands. I had planned to drop it on its wheels once I get the brakes done.

[mepstein]

Like others said, torque the stub axles. It will make a difference.

[davep]

Never roll the car without stub axles torqued down

[Superhawk996]

The car is on jack stands. I had planned to drop it on its wheels once I get the brakes done.

warning - if you put weight on those bearings without the stubs installed and torqued, you might as well order another set of bearings right now.

Life of the bearings will be degraded just by putting weight on them without the stubs installed. The rear bearings are a split race, double row ball bearing. They are not designed to support load without having preload on the bearing (via the stub).

Note: you can still install the axles after the stubs install and before the engine goes in.

[DennisV]

warning - if you put weight on those bearings without the stubs installed and torqued, you might as well order another set of bearings right now.

Note: you can still install the axles after the stubs install and before the engine goes in.

Thank you for the warning about the bearings. I was not aware of this.

Stubs separate from axles. Lightbulb moment from me. I rebuilt my CV and axle and assembled them with stub. It didn't occur to me that I could install the stub (aka Drive flange in parts catalog), separate from the axle (aka drive shaft). Though I'm guessing getting those bolt attached inside the trailing arm is not fun.

Curse you Ian Karr and your make it look easy videos! (Completely meant in jest Ian. Your videos are great.). He went down the same path as me. Installed the caliper without the stub. It worked for him!

[Superhawk996]

Extra long socket with triple square or hex drive bits are readily available depending on what fastener you’re using.

It really isn’t that big of a deal to install engine with the axles installed to the stubs. Just cover trans side CV with baggies and manipulate them to keep clear during engine install. I’ve done it both ways. Each has some pros & cons.