Brake booster rebuild kits available

[Max Lumens]

A couple of guys got preliminary bits and pieces earlier this year, and the full kits are available now. ALL of the replaceable interior components for the H31 hydraulic brake booster are available, so you can repair a simple leak or restore all the seals in the entire system. I haven't figured out pricing completely, but everything came in fairly reasonable, after a long wait for the teflon seals from Denmark. A simple seal and o-ring will be $6 plus envelope postage for 2 ounces on your SASE. Will publish full kit prices and rebuild instructions shortly; email inquiries welcome in the meantime.

More info at: http://bmw8.us/Brake%20Booster%20Rebuild.htm

[Benzz]

Hey I will buy one if this is available now

[Max Lumens]

Hey I will buy one if this is available now

Glad to oblige, but do me a favor; contact me by regular email at "e31parts@bmw8.us" or "booster@finemotoring.com". I can't track and archive online messages and emails.

For anyone who simply wants the primary oil seal and o-ring just to stop the obvious leak that these cars all have, what you do is mail $6 along with a self-addressed stamped envelope to:

Max Lumens
2458 West Shore Drive
Lummi Island WA 98262

Seems like the quick and easy way to handle it.

[fj60landcruiser]

I've got to comment on this one. Ordered it around the first of the year, high quality parts, and a great seller. There was a small snag with the parts and he handled it immediately, and with great customer service. Brakes feel great six months later, I would definitely buy from him again. Thanks

[bkmc]

I am interesting too.

[Max Lumens]

I need to make everyone aware that there is a defect in one of the seals in the booster rebuild kit. It's the one that goes in the rear position and seals against fluid going into the passenger compartment, over the brake pedal. When I had the kit made up, I sent an entire booster to the seal manufacturer. They recommended a polyurethane rear seal to replace the original rubber one. There is a chance that they can leak, even when installed well; their engineers made a mistake, and it would seem that poly is not a good choice for this application. If your existing rear seal is good and doesn't leak now, don't touch it; just leave it alone and use it again. All the other seals and o-rings are fine and work well; just don't go near the rear seal.

I'm having some NBR seals made up, but it's a slow process because a mold must be made. There are no other substitute seals nor any options besides buying a new cylinder (which, of course, is why I made the kits in the first place). I apologize for any inconvenience this has caused; in the future I will ask for multiple opinions on ANY engineering question.

[Marvis43]

That explains my delima, had shop rebuild booster and the next day it leaked from above the brake pedal. Not sure if they still have old seals so is there anything else I can do to solve my problem. I will call today to see if they kept old seals though.

[Max Lumens]

No current solution. Production quotes from ATE/Continental for the boosters start at 200 units, and there are two types for our cars. Seal is proprietary and they won't part with it, if they even have any on hand.

[smc850ci]

I was hoping to rebuild mine this summer, as the brakes are soft and there is a bit of a leak into the interior.
How long are we looking at in this "slow process"? BTW, what is NBR? Natural black rubber?
Thanks.

[frank735]

Are the kits still available Max?

[Prometheus]

Max, I will buy a full kit.

Please PM me if you're ever planning to stop by the portland area.

I would love to buy some parts, buy you a coffee & show you my project.

[macelius]

Anything like this for the e36 M3 (34312227466) BMC?

[56robbie60]

A while back I purchased an E31 Brake Booster Rebuild Kitfrom Max Lumens
A Buyer Beware would be in effectIMHO. I don’t know if this information has been posted or archived, but I wouldlike to caution on this particular product. By all means this is not an attackon Mr Lumens, however a caution on purchasing the complete E31 Brake Boosterkit from this source until a change or correction can be made. In reading onthe Forum, he has had the items made/machined. Now I can only speak for the totalRebuild Brake Booster Kit that I purchased from Mr Lumens and installed in my1991 six speed E31. I currently have 92000miles on the Bimmer. When the Brake Bomb failed I replaced the Bomb, and due tothe amount of miles I had on the original brake system, I decided to rebuildthe brake booster and service all I could reference the brake system. I decidedto rebuild the Brake Booster with Mr Lumens kit to ward off a future fail ofthe original OEM Brake Booster. Let me note my original OEM brake Booster hadnot failed, so I should have just left it alone. Upon purchasing the totalrebuild kit, installing the parts into my OEM Brake Booster, I went through thetedious task of reinstalling the part. Upon completion of reinstalling the BrakeBooster, power bleeding the brake system with Blue Dot 4, flushing out andbleeding the Hydraulic system with fresh cans of CHF 7.1, I believed I was allset. I took the ole girl out for a spin, and noticed immediately a slow return ofthe brake pedal and whine of the power steering if I turned the wheels left toright at slow speeds, or while stationary. I thought at first that since Iinstalled new seals and the aluminum front cup replacement part with seal, thatmaybe I needed to give the seals a lil time to break in. Now the 8 is not adaily driver and since installing the Rebuild Kit, I have put approximately700-800 miles on the car. As of last week and over approximately 12-15 months ormore since installation, I still have had the same issues” Slow Brake Pedalreturn to where in order to get the brake light off and release brake pad drag,I had to use my left or right foot to pull the brake pedal up to release thebrakes pad drag and turn off the brake light while moving from a stop, or experiencelag and brake drag. I would experience an up to 10 second lag sometimes, evenif the vehicle was in motion. So now tired of this unsafe situation, Ipurchased a refurbished Brake Booster and over the weekend installed it. Therefurbished Brake Booster worked like a charm. No more slow brake pedal returnor power steering whining. An “Immediate Fix”. What I spent on Lumens totalrebuilt kit, I could have put toward a new or refurbished brake booster. SinceI cannot use the rebuilt booster. Now upon reading through this Forum, as faras what people have mentioned about having the same issues with their brakingsystem after installing the parts or product(s) received from Mr Lumens, reference;slow to return brake pedal and steering whining. It has come to my logicalopinion that something is wrong or not right with what we are receiving fromhim to correctly rebuild our E31 brake Boosters. In doing research as to why abooster/pedal would slow return to its original position and whine the steeringunit, it has come to my understanding from reading/research that the whine iscaused by a pressure issue/blockage in the steering gear or return line causingthe slow pedal return. These hose and line connections are directly connectedto the brake booster. A pressure fault or problem within the brake booster willdirectly affect the pressure flow into these lines. Whatever the case may be, Ibelieve more research needs to be done with Lumens complete kit, before it isinstalled in to an 8 series brake booster since these slow to release pedalproblems are not isolated and an issue. My guess would be the culprit which iscausing this issues is the switching out the original black front cup assemblyfor the aluminum one. A Refurbish Booster or new booster has only the black plasticfront cup assembly and not an aluminum one. Folks correct me if I’m wrong’ no foul.

[Wuffer]

Have had 0 issues with the 1/2 dozen plus rebuilds I have done using Max's kit all with the aluminum front cup assembly. FWIW...
Have alerted Max to this post so he can chime in - he is a reasonable guy.

[Max Lumens]

The likeliest culprit for your scenario is the connecting rod between the booster and the master cylinder. Did you pay attention to which direction you installed it? Second likeliest culprit is the master cylinder itself; they bind sporadically when they're failing, and yours may still bind later on even with the "rebuilt" booster you purchased. (Which, if you got it from Cardone, is arguably "re-conditioned" rather than "rebuilt", based on the ones I've seen).

There are other possible failure modes, but please note that the kit I sell simply contains identical replacement seals and piston rings for the originals. Installed properly, there's nothing to fail in the manner you describe. Hundreds have been sold to owners of numerous types of vehicles without incident. The front cone is merely a static seal carrier. If your pedal is slow, check to see that the large spring is in correctly and that the teflon and rubber rings on the sliding pistons were installed correctly.

Note too that I pro-actively and immediately corrected early engineering deficiencies for the buyers who received those original kits many years ago.

[BMSman]

Wow! I have exactly the same issue with my car (1991 850i). Almost exactly the same scenario as well....

I installed Max's complete rebuild kit and my brake pedal no longer returns quickly or fully and my steering is noisy when maneuvering in my driveway. At the same time I did this job I also installed a rebuilt steering box and a brand new master cylinder. I had hoped the brake pedal would loosen up after a while but your post suggests not. I was meticulous in my rebuild (took lots of pics) and am quite certain it went back together in the same way it was dismantled. i installed the full kit with the aluminum cup. It was a lot of work and whilst I'm happy that you may have solved my issue I'm upset that nothing has been posted on this. This is the first time I have read of this but you suggest others have had similar issues? May I ask where you purchased the replacement? I had the top end apart when I did this job which made it much easier, now it's all back together

A while back I purchased an E31 Brake Booster Rebuild Kitfrom Max Lumens
A Buyer Beware would be in effectIMHO. I don’t know if this information has been posted or archived, but I wouldlike to caution on this particular product. By all means this is not an attackon Mr Lumens, however a caution on purchasing the complete E31 Brake Boosterkit from this source until a change or correction can be made. In reading onthe Forum, he has had the items made/machined. Now I can only speak for the totalRebuild Brake Booster Kit that I purchased from Mr Lumens and installed in my1991 six speed E31. I currently have 92000miles on the Bimmer. When the Brake Bomb failed I replaced the Bomb, and due tothe amount of miles I had on the original brake system, I decided to rebuildthe brake booster and service all I could reference the brake system. I decidedto rebuild the Brake Booster with Mr Lumens kit to ward off a future fail ofthe original OEM Brake Booster. Let me note my original OEM brake Booster hadnot failed, so I should have just left it alone. Upon purchasing the totalrebuild kit, installing the parts into my OEM Brake Booster, I went through thetedious task of reinstalling the part. Upon completion of reinstalling the BrakeBooster, power bleeding the brake system with Blue Dot 4, flushing out andbleeding the Hydraulic system with fresh cans of CHF 7.1, I believed I was allset. I took the ole girl out for a spin, and noticed immediately a slow return ofthe brake pedal and whine of the power steering if I turned the wheels left toright at slow speeds, or while stationary. I thought at first that since Iinstalled new seals and the aluminum front cup replacement part with seal, thatmaybe I needed to give the seals a lil time to break in. Now the 8 is not adaily driver and since installing the Rebuild Kit, I have put approximately700-800 miles on the car. As of last week and over approximately 12-15 months ormore since installation, I still have had the same issues” Slow Brake Pedalreturn to where in order to get the brake light off and release brake pad drag,I had to use my left or right foot to pull the brake pedal up to release thebrakes pad drag and turn off the brake light while moving from a stop, or experiencelag and brake drag. I would experience an up to 10 second lag sometimes, evenif the vehicle was in motion. So now tired of this unsafe situation, Ipurchased a refurbished Brake Booster and over the weekend installed it. Therefurbished Brake Booster worked like a charm. No more slow brake pedal returnor power steering whining. An “Immediate Fix”. What I spent on Lumens totalrebuilt kit, I could have put toward a new or refurbished brake booster. SinceI cannot use the rebuilt booster. Now upon reading through this Forum, as faras what people have mentioned about having the same issues with their brakingsystem after installing the parts or product(s) received from Mr Lumens, reference;slow to return brake pedal and steering whining. It has come to my logicalopinion that something is wrong or not right with what we are receiving fromhim to correctly rebuild our E31 brake Boosters. In doing research as to why abooster/pedal would slow return to its original position and whine the steeringunit, it has come to my understanding from reading/research that the whine iscaused by a pressure issue/blockage in the steering gear or return line causingthe slow pedal return. These hose and line connections are directly connectedto the brake booster. A pressure fault or problem within the brake booster willdirectly affect the pressure flow into these lines. Whatever the case may be, Ibelieve more research needs to be done with Lumens complete kit, before it isinstalled in to an 8 series brake booster since these slow to release pedalproblems are not isolated and an issue. My guess would be the culprit which iscausing this issues is the switching out the original black front cup assemblyfor the aluminum one. A Refurbish Booster or new booster has only the black plasticfront cup assembly and not an aluminum one. Folks correct me if I’m wrong’ no foul.

[jcs1966]

My first thought when reading this was the pedal linkage as well. I haven't had this issue, and many others haven't. It might be interesting to do some R&D to try and replicate it. Just my thoughts.

[56robbie60]

Wow! I have exactly the same issue with my car (1991 850i). Almost exactly the same scenario as well....

I installed Max's complete rebuild kit and my brake pedal no longer returns quickly or fully and my steering is noisy when maneuvering in my driveway. At the same time I did this job I also installed a rebuilt steering box and a brand new master cylinder. I had hoped the brake pedal would loosen up after a while but your post suggests not. I was meticulous in my rebuild (took lots of pics) and am quite certain it went back together in the same way it was dismantled. i installed the full kit with the aluminum cup. It was a lot of work and whilst I'm happy that you may have solved my issue I'm upset that nothing has been posted on this. This is the first time I have read of this but you suggest others have had similar issues? May I ask where you purchased the replacement? I had the top end apart when I did this job which made it much easier, now it's all back together

Iordered the Brake Booster online from Parts Geek http://www.partsgeek.com
Iwas taking a chance on it and it works flawlessly. Replacing the Booster was myonly option in a first step to troubleshoot the issue since I did not have theissue until I installed the Booster Kit from Max. It is an A1 Cardoneremanufactured OEM product. Max wasright on that, part # 1158-05003618condition remanufactured to OEM specs. I don’t know if Max’s kit rebuildsto OEM specs. I have been working on cars since I was at least 15 years old. Iam in my fifty’s now. I do know how to read and follow directions. I am mostlikely a perfectionist when taking things apart and putting them back togetheragain. There is others on this forum who have mention that they have orderedkits from Max and they worked perfectly, and the same person again noted on another rebuild they experienced the slow brakepedal return and the steering whining. That is what leads me to believe thatthese are not isolate incidents and that something else is taking place or iswrong with something in this kit when installing this complete particularrebuild kit. Hit and miss maybe. I probably would not have taking the time to mentionthis if I didn’t read of others having this same problem. We all can’t be wrongor have somehow screw up when putting the booster back together againexperiencing the same symptoms. I’m simply saying yes I believe there is anissue here that's need to be looked into. The full rebuild kit that Max offersis not cheap. Satisfaction has to be the result.


- - - Updated - - -

Wow! I have exactly the same issue with my car (1991 850i). Almost exactly the same scenario as well....

I installed Max's complete rebuild kit and my brake pedal no longer returns quickly or fully and my steering is noisy when maneuvering in my driveway. At the same time I did this job I also installed a rebuilt steering box and a brand new master cylinder. I had hoped the brake pedal would loosen up after a while but your post suggests not. I was meticulous in my rebuild (took lots of pics) and am quite certain it went back together in the same way it was dismantled. i installed the full kit with the aluminum cup. It was a lot of work and whilst I'm happy that you may have solved my issue I'm upset that nothing has been posted on this. This is the first time I have read of this but you suggest others have had similar issues? May I ask where you purchased the replacement? I had the top end apart when I did this job which made it much easier, now it's all back together

Sorry Folks don't know why computer bunched up the words.
Resubmitting;

I orderedthe Brake Booster online from Parts Geek http://www.partsgeek.com
I was taking achance on it and it works flawlessly. Replacing the Booster was my only optionin a first step to troubleshoot the issue since I did not have the issue untilI installed the Booster Kit from Max. It is an A1 Cardone remanufactured OEMproduct. Max was right on that, part # 1158-05003618 condition remanufacturedto OEM specs. I don’t know if Max’s kit rebuilds to OEM specs. I havebeen working on cars since I was at least 15 years old. I am in my fifty’s now.I do know how to read and follow directions. I am most likely a perfectionistwhen taking things apart and putting them back together again. There is otherson this forum who have mention that they have ordered kits from Max and theyworked perfectly, and the same person again noted on another rebuild theyexperienced the slow brake pedal return and the steering whining. That is whatleads me to believe that these are not isolate incidents and that somethingelse is taking place or is wrong with something in this kit when installingthis complete particular rebuild kit. Hit and miss maybe. I probably would nothave taking the time to mention this if I didn’t read of others having thissame problem. We all can’t be wrong or have somehow screw up when putting thebooster back together again experiencing the same symptoms. I’m simply sayingyes I believe there is an issue here that's need to be looked into. The fullrebuild kit that Max offers is not cheap. Satisfaction has to be the result.

[Max Lumens]

There is a repair manual procedure for adjusting the brake pedal linkage in sections 34 and 35, with the correct pedal height called out in the specifications section. What do you make of this wording? "Caution! Stroke restriction must take place in the master brake cylinder and not, for instance by the brake light switch".

Once again, the parts in my rebuild kit are identical in every respect to the parts that ATE put in the booster when they built it. I can't guess at the failure mode for a 2mm x 32mm NBR o-ring. How do you suppose it could go wrong, Robbie?

You're still gaining experience, young man. I've been mauling cars since I was 13 and I'm 62 now. You'll get the hang of it eventually 8^)

[56robbie60]

Lol !!
Max I guess it’s ok to agree to disagree. I cannot considerreferencing a manual for adjusting the brake pedal linkage. I didn’t have thatissue before I installed your kit and that issue doesn’t exist with the remanedbooster. If that was the case, then I would still have a linkage adjustmentproblem upon installing the newer booster remaned by Cardone, and would nothave needed to purchase another booster if that was the fix, but it wasn’t. Also the issue of the whine has beeneliminated with the installation of the newer booster. Again all the problemsthat I was experiencing when I installed your kit ceased upon the installationof the newer booster, that I didn’t have before until installing your kit. Andagain others have experienced the same issue I was having. This is not anattack on you Max, just info in reference to this particular issue that neededto be put out there. The cause of the problem Max” I have no clue, but its an unsafeone and an annoyance, and I cannot trouble shoot the issues of the old booster,it had its chance to work properly. It will no longer be used. I can send it toyou if you like, if you have a way of troubleshooting it. Something good maycome from it. If we are experiencing problems with our cars, good or bad, isn’tthis the place to brain storm it? I purchase this product from you and trustedthat it would work, it didn’t. So in all fairness shouldn’t it be brought toyour attention? Oh and by the way thank you for the age complement, being thatyou are only six years older.Just athought this problem may be isolated to the 1991 e31 six speed manual. Howeverthe tangible problem does exist.
A solution is better than an argument.
I can’t say or addanything more pertaining to this, because at this time the problem and fix withthe old booster is unknown, other than what I have already done, replace theunit, and got a total fix. I can drive the car safely now:)I will post some photos of other 8 projects Ibelieve the 8 community may be interested in at a later date. Have to drop thegas tank to find out where this Gas Leak is coming from! Only happens if I fillup the tank. Other than that anything at or below ¾ tank no leak.

BMSman Thank You!!!
In re reading your post plus all post again, logic would have to dictate that If you didn't have the issue before the rebuild, then it’s something in the rebuild you and I installed. Can't blame it on working parts that were fine before. And again no one is commenting on what is causing the steering whine. Why is it with a complete replacement the symptoms are gone that Lumens kit created? Just a thought. In reference to this issue, it’s not the master cylinder bake thing part" especially if you have a new master cylinder.

[cartoonz]

The likeliest culprit for your scenario is the connecting rod between the booster and the master cylinder.

That'll do it. Easy to mix up too.

[BMSman]

I don't think that is the problem. It is very easy to differentiate the two ends and the instructions are quite clear as to which end faces the master cylinder. I can say this because I am having exactly the same issue with mine and my connecting rod is definitely in correctly. In my case the seals are much tighter than I would have expected but I've only worked on this one so I don't have anything to compare it to. And it's not the aluminum cup either.

One thing that bugs me is the seal on the actuator shaft (bulkhead side).... It is very tight and impossible to push the actuator through (from the inside) without some sort of a mandrel. Yet in all the write-ups I have seen I don't recall this ever being mentioned.

[BMSman]

I did some more work on this this evening and believe I have identified the problem (brake pedal not fully returning when released). If you saw my video in the main section the input shaft was extremely tight. So I removed the seal on the input shaft and without it, the piston moves smoothly with about the resistance I would expect.... The large internal spring will easily return it when the brake pedal is released.

This prompted me to go looking for the seals I removed when I rebuilt the unit which fortunately I had kept. Below is a pic of the original input shaft seal on the left and the seal I received in Max's kit on the right.
001.JPG
As you can see, the replacement seal is much larger than the original - which made it extremely difficult to press the shaft through from inside (I had to make a special tool to do so). It grips the input shaft so tight the internal spring can not completely overcome the friction. Hopefully this was just an oversight and Max can supply the correct seal.

In my frustration with this I too ordered a replacement brake booster today now hopefully I won't need it!

[Max Lumens]

BMSman, What is the diameter of your input shaft?

- - - Updated - - -

Robbie, you don't need to drop the gas tank; save yourself some toil by searching the archives. There's pretty much no symptomatic reason to ever drop the tank.

I'm glad to hear that buying a Cardone unit solved your problem. Since you wouldn't "consider referencing a manual" about the brake pedal linkage, I guess we'll never know what the problem was. You should still check to see that there's some slack in the pedal rod at full extension.

[56robbie60]

Max I will reference the manual about the brake pedal linkage : ) but I'm thinking I may have the same seal BMSman, mentioned since we had the same issues with the booster, reference rebuild. I will dismantle the older booster and let you know. I haven't dropped the tank yet wasn't quite looking forward to that task Lol!!. I have researched other's write ups as you have suggested and will put them to practice. The gas tank leak issue is the last issue/problem in an almost total restoration.


See new post on Double Din and E46 Arm Rest installation. I'm still getting use to navigating through this site.