Bad brake piston

[Forssling]

Hi All, I have removed the pistons from my front calipers of my 71 911T.

One of them was a bit damaged. See photos.

1) Should I get a new one or is this damage "on the right side" of the seal?
2) If I should replace it, can I get OE pistons somewhere?
3) If I replace, do I have to replace both in the same caliper?

Thanks for any input!

Jörgen Forssling
Göteborg
SWEDEN

[DRACO A5OG]

Contact Bigg Reds in the U.K. if you race your car, contact Chris Seven here, he make Titanium pistons, also in U.K.

I just ordered rears from Bigg Reds, they are NLA here in the states.

[Forssling]

Originally Posted by DRACO A5OG

Contact Bigg Reds in the U.K. if you race your car, contact Chris Seven here, he make Titanium pistons, also in U.K.

I just ordered rears from Bigg Reds, they are NLA here in the states.

Thanks for your reply!

I guess this means I should replace the piston? Just the damaged one or both? Or all four in front?

//Jörgen

[trond]

Replace ! I just ordered new ones from Bigg Red in the UK myself. Even if your old piston should work after assembly it will cause trouble

[Forssling]

Originally Posted by trond

Replace ! I just ordered new ones from Bigg Red in the UK myself. Even if your old piston should work after assembly it will cause trouble

Replace the one or all?

//Jörgen

[trond]

Bigg Red

you will need to call them or e-mail them to find the correct part numbers

[Forssling]

I mailed them already! But what do you think about replacing all or just the one?

//Jörgen

[Discseven]

Jorgen... replacing all serves to maintain "balance" in the system. In other words, it is possible for a new part to behave differently than an old part. While that's acceptable in certain areas, it's undesirable where performance braking is concerned.

(If pistons are not looking good, what do cylinders look like?)

[Forssling]

Originally Posted by Discseven

Jorgen... replacing all serves to maintain "balance" in the system. In other words, it is possible for a new part to behave differently than an old part. While that's acceptable in certain areas, it's undesirable where performance braking is concerned.

(If pistons are not looking good, what do cylinders look like?)

Thanks!
I'm looking for a used piston to replace the damaged one. If I can't find one, I will replace all of them in the front.

The cylinders looks perfect actually. I think this damaged piston was put in by PO back when these cars were not so appreciated as now.

//Jörgen

[DRACO A5OG]

YES, replace all four pistons.

But if you are on a limited budget, then I understand, you have to do what you have to do.

Yeah, don't post the pics of your calipers here, others will or may not consider it perfect because if the PO gouged the piston/s like that and put them back in like that the walls could be damaged of the caliper/s. Just my 2 cents.

Good Luck with your repair.

[Forssling]

I will check the calipers thoroughly once I split them. Even though I'm on a budget I won't put in bad parts regarding the brakes.

//Jörgen

[DRACO A5OG]

Split? Sure you want to do that? Gosh, if you don't have to, I would not recommend that, some have issues sealing the caliper after a split.

Just make certain you can not feel any imperfections on the piston receiver walls. As far as the seal grove, I used an angle fitting for my dremel tool and used a the plastic wire wheel to clean the grove out before installing a new seal. Do not use a metal cleaning tool on the walls.

Good Luck Brother

[Forssling]

Originally Posted by DRACO A5OG

Split? Sure you want to do that? Gosh, if you don't have to, I would not recommend that, some have issues sealing the caliper after a split.

Just make certain you can not feel any imperfections on the piston receiver walls. As far as the seal grove, I used an angle fitting for my dremel tool and used a the plastic wire wheel to clean the grove out before installing a new seal. Do not use a metal cleaning tool on the walls.

Good Luck Brother

Thanks! I guess I need that. I'm going to replate the calipers and bolts so there is no other way than full disassembly.

Learning by doing...

//Jörgen

[DRACO A5OG]

I hear you Brother , well, POSITIVE thoughts for you and keep us posted on your progress.

Jim

[Forssling]

I will! Cheers!

//Jörgen

[LM3929]

always replace pistons, calipers,or brake pads in pairs as a minimum and by the way that piston is way beyond saving even for a paper weight.

Lorne M.

[DRACO A5OG]

LOL, I use my old one to keep the lid on the grease jar closed

[Forssling]

Originally Posted by LM3929

always replace pistons, calipers,or brake pads in pairs as a minimum and by the way that piston is way beyond saving even for a paper weight.

Lorne M.

Thats what I wanted to know.

Thanks!

//J

[Porboynz]

When you get them re-plated, I suggest you bolt the calipers back together with standard bolts to prevent the machined surfaces plating and also it prevent mix ups. You do not want to plate the original bolts. Make sure you source the correct Ribe socket to hold the head while torqueing up the nut and be very sure of your torque wrench accuracy, I suggest a 3/8 or even 1/4 inch drive torque wrench. I sourced replacement O rings from Mercedes, same part used in a Mercedes Unimog caliper, who knew? That piston is not re-useable, if the others are the same then replace all of them. By the time you strip, re-plate, new pistons and seals and re-assemble you should compare cost with aftermarket reproduction calipers. I did exactly what you are planning to do and now regret not sourcing PMB refurbished units. The plating finish ended up incorrect and many other hassles. I appreciate that sending cores to PMB and freight back is a killer from Sweden but take a look at the calipers from design911.com
One other tip is a local brake shop was able to rebuild my pistons with a stainless steel sleeve, but they were in better shape than the photo you posted, looks like they have been attacked with vice grips or worse. Good luck.

[Forssling]

Originally Posted by Porboynz

When you get them re-plated, I suggest you bolt the calipers back together with standard bolts to prevent the machined surfaces plating and also it prevent mix ups. You do not want to plate the original bolts. Make sure you source the correct Ribe socket to hold the head while torqueing up the nut and be very sure of your torque wrench accuracy, I suggest a 3/8 or even 1/4 inch drive torque wrench. I sourced replacement O rings from Mercedes, same part used in a Mercedes Unimog caliper, who knew? That piston is not re-useable, if the others are the same then replace all of them. By the time you strip, re-plate, new pistons and seals and re-assemble you should compare cost with aftermarket reproduction calipers. I did exactly what you are planning to do and now regret not sourcing PMB refurbished units. The plating finish ended up incorrect and many other hassles. I appreciate that sending cores to PMB and freight back is a killer from Sweden but take a look at the calipers from design911.com
One other tip is a local brake shop was able to rebuild my pistons with a stainless steel sleeve, but they were in better shape than the photo you posted, looks like they have been attacked with vice grips or worse. Good luck.

Lots of good advice there, thanks a bunch!

I have the right Ribe bits. And will follow your advice regarding plating the caliper assembled with other bolts.

The other pistons are fine, thats why I'm hesitating on putting in new. And the cost is what it is in this hobby. But I enjoy doing things myself and learning. There are firms here in Sweden that could do the caliper too.

Cheers,
Jörgen