Need Brake Booster and Master Cylinder 1972 CS 3.0

J

Jamison

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Greetings Bimmer Friends:

Please help me stop!

My mechanic is stating that I need a replacement master cylinder and brake booster for me 1972 3.0 CS.

If you have parts in good condition and for sale, kindly reach out to me. I reside in NJ USA.

Alternatively, if you can recommend a reputable source for aftermarket or NOS solutions, please advise.

Thank you,

James
 
Reach out to @sfdon these are parts he may be able to help you locate. Neither of these is cheap unfortunately. Another option is to reach out to @halboyles at his 2002sonly.com website, he has a modified 2002Tii which is intermittently in stock
 
www.wallothnesch.com

Brake force booster for 2800 CS for all years of production, 3.0 CS up to serial number 2231194, 3.0 CSI up to serial number 2262255 and for 3.0 CSL up to June 1972 only for LHD models (only in combination with push-rod 34 33 1 103 601) you need 1 fo

Brake force booster for 2800 CS for all years of production, 3.0 CS up to serial number 2231194, 3.0 CSI up to serial number 2262255 and for 3.0 CSL up to June 1972 only for LHD models (only in combination with push-rod 34 33 1 103 601) you need 1 for 1 car
www.wallothnesch.com www.wallothnesch.com
 
You should attach a picture of what your brake booster. Looks like there were two available. It’s important to find out which one you have in your car.
 
It is funny that we are all looking for this part.

My brake assist/booster is not functioning. It is the small 7” diameter unit versus a large 10 inch diameter unit. Paragraph

so I talked to a friend of mine that has forgotten more than I know about old BMWs. I have an order a brake booster from a 2007 to 2010 E9X style car.

It was about 85 bucks from eBay

I’ll let you know how the retrofit works.
 
IMG_3322.jpeg
The e9x brake booster.
 
IMG_3320.jpeg
Down below, you can see the old brake booster.

Obviously, the master cylinder has been removed.

I can make the E9X brake booster fit into place. I can make adjustments in the long brake pedal shaft.

What I’m having trouble with is retrofitting the old E9 master cylinder to this new E9Xbooster.
 
IMG_3329.jpeg

The brake line diameter on the E9X automobiles is much longer not to mention there are only two ports on the E9X master cylinder. so, use of the E9X master cylinder is not an option.

Our E9 master cylinder has five ports. Two for each front wheel and one port that goes to the back brake lines. Obviously the brake lines that I have fabricated for the car work well with the existing E9 master cylinder.

I’m going to search for an old master cylinder. I will cut the silver extension shaft off of the donor master cylinder. Then, I will see see if I can make the internal shaft length longer by welding a shaft extension onto the existing e9 shaft (top picture),

Wish me luck.

Your thoughts and words of encouragement are greatly appreciated.

RP
 
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Oops, by the way, I’ve already pulled the old brake booster off. I made the assumption that it was bad.

I shouldn’t have assumed as much without testing. What should I have done to test the old master cylinder?

The problem with the car was that it would stop, but there was very little brake assist. You had to plan well in advance that you were going to reduce the speed to zero

Thank you,RP.
 
If you HAVE an old brake booster then I would just have that rebuilt. Far easier than trying to retrofit this part. Power Brake Exchange as listed in the FAQ did mine and did a good job. There's also a place up here in Washington called Power Brake Boost Exchange that focuses on older muscle cars but may be able to do the work. They apparently also can rebuilt master cylinders. As someone who has done some "upgrading" of parts vs rebuilding, there are times the upgrade seems to have been worth it but I also have instances in which it has made the job way more difficult and I should have just done the rebuild. This seems to fall into that category.
 
Booster operates on vacuum. It should keep vacuum to be able to support. To realize that the membrane inside should be without any cracks. Also the inside should be free from rust. You may look with the inspection camera.

Applying vacuum with hand vacuum pump with vacuum meter should help too to check if it operates freely and keeps vacuum.
 
I have a booster that I took off my car, put on a tii unit, was working perfectly.
Please PM .
Best,
Alberto
 
Just a thought, where are you pulling vacuum from? You appear to have ITB's? If you are only pulling vacuum from one cylinder, you will simply not have enough to give you boost. I would have thought you need to pull vacuum off at least three (but preferably all six) cylinders.
 
Thanks e9Leveque.
I canceled the E9X master cylinder experiment parts idea.

I spoke with the gentleman at Power Brake Booster exchange (Washington state guys) and I’ve sent my old core to him. He was super helpful on the phone.Hopefully he can rebuild it.

Again, thank you.

RP
 
Patton said:
Thanks e9Leveque.
I canceled the E9X master cylinder experiment parts idea.

I spoke with the gentleman at Power Brake Booster exchange (Washington state guys) and I’ve sent my old core to him. He was super helpful on the phone.Hopefully he can rebuild it.

Again, thank you.

RP
Click to expand...
I have a large original booster from my 72 3.0CS. I am switching to the Tii booster. LMK if you are interested
 
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