e28Goodies.com Brake Booster Upgrade

E28 technical advice asked and given! Troubleshooting, modifications and more.
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Yojedi
Posts: 143
Joined: Oct 18, 2016 1:42 AM
Location: Orange County, CA

e28Goodies.com Brake Booster Upgrade

Post by Yojedi »

I was browsing e28goodies.com website yesterday and came across this Brake Booster Upgrade DIY article;

The “must-have” budget e28 brake upgrade
https://e28goodies.com/the-must-have-bu ... e-upgrade/
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I am already doing the caliper upgrade as suggested. But what really hat caught my attention was the using of an E34 double-diaphragm brake booster to eliminate the infamous E28 brake bomb. I have yet to see one of these double-diaphragm boosters up close but judging from the picture the booster appears to be too big to fit in place of the existing e28 booster.

The subsequent brake boosting improvement is a plus, but being able to completely eliminate the brake bomb is supreme! I am curious if anyone here has done this upgrade. Would love to hear your feedbacks.
M5BB
Posts: 1530
Joined: Jun 13, 2007 10:13 AM
Location: Peachtree Corners, Georgia

Re: e28Goodies.com Brake Booster Upgrade

Post by M5BB »

Myself and some friends have had bad experiences with e28Goodies.
Items don't arrive for months or are so badly packaged that they are damaged or parts missing.

Do some searching and you will see complaints.

Just trying to save you some hassle.
demetk
Posts: 8244
Joined: Aug 09, 2007 8:58 AM
Location: CT, USA

Re: e28Goodies.com Brake Booster Upgrade

Post by demetk »

I'm using one of these boosters in my conversion. You can get them on ebay. The nice thing about them is that if you use the spacer on the back you don't need to relocate the heater valve. You can see the Lucas part number on it. IIRC the only thing I did was put some more threads on the connecting rod to the brake pedal.

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Bonsaibacker
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Location: Savannah GA

Re: e28Goodies.com Brake Booster Upgrade

Post by Bonsaibacker »

M5BB wrote: Jan 04, 2021 10:05 PM Myself and some friends have had bad experiences with e28Goodies.
Items don't arrive for months or are so badly packaged that they are damaged or parts missing.

Do some searching and you will see complaints.

Just trying to save you some hassle.
I agree. Some of their advice is hackish. Interested in this one though.
Yojedi
Posts: 143
Joined: Oct 18, 2016 1:42 AM
Location: Orange County, CA

Re: e28Goodies.com Brake Booster Upgrade

Post by Yojedi »

demetk wrote: Jan 04, 2021 10:18 PM I'm using one of these boosters in my conversion. You can get them on ebay. The nice thing about them is that if you use the spacer on the back you don't need to relocate the heater valve. You can see the Lucas part number on it. IIRC the only thing I did was put some more threads on the connecting rod to the brake pedal.

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This is exactly what I wanted to see. Thanks very much for the tip on using the spacer. One question about the conversion though. The Double-Diaphragm Brake Booster REPLACES the E28 Single-Diaphragm Booster + DS Regulator + Brake Bomb. With the DS Regulator gone which also means its two pressure switches gone, what did you do with the pressure switch input wires? NO CONNECT as they are no longer needed?

On brake performance do you notice any improvement or different feel at all?

Sorry but I couldn't quite make out the LUCAS part number. Can you please identify it?

Thanks,
adam_poll
Posts: 76
Joined: Jul 23, 2014 8:19 PM
Location: Kitchener, Ontario, Canada

Re: e28Goodies.com Brake Booster Upgrade

Post by adam_poll »

On my mainly track car E28 I also eliminated the hydraulic brake booster, not because it didn't work but because the assist was too much and was very hard to be consistent with on track threshold braking. Basically with the hydraulic setup instead of pedal pressure determining how hard the brakes were being applied it was more of how far the pedal was being pushed down.

I used a standard E28 brake booster from a 528e which cleared the M30 without any issues, it did require the heater valve to be moved though (I am running an E46 valve at this point Anyway). The assist level is less than with the hydraulic setup but still plenty for my needs which is what I wanted with a nice firm pedal when you get on them hard.

I just disconnected the pressure switch wiring from what I remember and do not have any lights because of it. For the power steering reservoir I just looped a line between the two unused ports, at some point I'd like to get a 528e reservoir though to eliminate that potential leak. I also needed a new power steering line from the steering box back to the pump which was just a 528e part as well. For the vacuum I modified the idle control circuit plumbing on the manifold side to get my source from there, that was easier then trying to tap into the intake manifold for a dedicated vacuum line.

My brake setup on my car now uses E34 540i/E32 750il calipers and rotors front and rear with stainless braided lines, an e32 25 mm master cylinder along with the 528e vacuum booster setup.
demetk
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Re: e28Goodies.com Brake Booster Upgrade

Post by demetk »

Brakes are immediate and precise with great feel. The engine is making plenty of vacuum for the booster to operate. And when the engine is making little to no vacuum, like when it's under high load or when the turbo is boosting, the brake booster has sufficient reserve vacuum capacity for quite a few brake presses, although if you think about it, I doubt if there would ever be a situation where you would be accelerating and using the brakes at the same time. :)

The pressure switch connections you would just tape them up and tuck them away since they're not needed.

One other mod you would need is to drill and tap the manifold for the vacuum line to the booster. One way brake booster check valves are crazy cheap on ebay so there's no need to buy a BMW valve.

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demetk
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Re: e28Goodies.com Brake Booster Upgrade

Post by demetk »

We should create a separate thread and move this information over.
M5BB
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Joined: Jun 13, 2007 10:13 AM
Location: Peachtree Corners, Georgia

Re: e28Goodies.com Brake Booster Upgrade

Post by M5BB »

Not to mud up the story but there are other ways.

I rebuilt my E9 3.0 CS with a souped up motor and triple side draft Webers.

It had a huge vacuum brake booster that was in the way of the Webers.
A 2002 Tii vacuum brake booster is smaller and used that for a couple years till I got to the rebuild.

A popular "upgrade" for an E9 is to use the booster system we are so familiar with in an E28.
I knew those problems and cost of parts and stayed away.

I went to a GM based Hydraboost system that still used the power steering pump as power, uses a GM master $75.
They also make an electric version which might be good for a track car.
http://www.hydratechbraking.com/
Other companies as well have similar systems. This company was very helpful with calculations for pedal pressure and connections.

Gary
Yojedi
Posts: 143
Joined: Oct 18, 2016 1:42 AM
Location: Orange County, CA

Re: e28Goodies.com Brake Booster Upgrade

Post by Yojedi »

demetk wrote: Jan 05, 2021 11:42 AM
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Can't seem to locate this Lucas part anymore. Nothing but rebuild services popped up in search. Only option is going with genuine BMW part which costs nearly $700. Anyone has an OE souce?
Yojedi
Posts: 143
Joined: Oct 18, 2016 1:42 AM
Location: Orange County, CA

Re: e28Goodies.com Brake Booster Upgrade

Post by Yojedi »

demetk wrote: Jan 05, 2021 11:42 AM
One other mod you would need is to drill and tap the manifold for the vacuum line to the booster. One way brake booster check valves are crazy cheap on ebay so there's no need to buy a BMW valve.
Got lucky and scored a brake booster and brake master cylinder off an '89 E34 at the local yard. All for $55. Where on the manifold did you tap for the vacuum line fitting? Not sure if the the center area of the manifold has enough material thickness for tapping. Would appreciate your comment.
Last edited by Yojedi on Jan 13, 2021 6:45 PM, edited 1 time in total.
demetk
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Re: e28Goodies.com Brake Booster Upgrade

Post by demetk »

I drilled here. Seemed like a good place to keep the hose short and out of the way. Used grease on the drill bit to catch the shavings.

Image

cheers.
Yojedi
Posts: 143
Joined: Oct 18, 2016 1:42 AM
Location: Orange County, CA

Re: e28Goodies.com Brake Booster Upgrade

Post by Yojedi »

demetk wrote: Jan 13, 2021 6:35 PM I drilled here. Seemed like a good place to keep the hose short and out of the way. Used grease on the drill bit to catch the shavings.

Image

cheers.
Demetk,

Roger that. Booster replacement looks like a straight forward install. However once the DS Regulator/Brake Bomb is eliminated, did you have to make a custom high-pressure power steering line running from PS pump to PS gear box directly since DS Regulator was the intermediate between PS pump and PS gear box?
demetk
Posts: 8244
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Location: CT, USA

Re: e28Goodies.com Brake Booster Upgrade

Post by demetk »

Yojedi wrote: Jan 15, 2021 10:45 AM Demetk,

Roger that. Booster replacement looks like a straight forward install. However once the DS Regulator/Brake Bomb is eliminated, did you have to make a custom high-pressure power steering line running from PS pump to PS gear box directly since DS Regulator was the intermediate between PS pump and PS gear box?
Good question. I forget. :) Let me take a look at what I did for the hose. I may have used pieces of the existing hoses into one hose to fit.
adam_poll
Posts: 76
Joined: Jul 23, 2014 8:19 PM
Location: Kitchener, Ontario, Canada

Re: e28Goodies.com Brake Booster Upgrade

Post by adam_poll »

This is the exact part I used as mentioned above, it's the high pressure line that goes directly from the pump to the steering box for a 528e. The original routing had a high pressure line from the pump to accumulator and then another down to the box.

https://www.rockauto.com/en/moreinfo.ph ... 2183&jsn=2

You will need to do something about the extra return ports on the reservoir as well, I just looped the two unused ones together but the better solution is a different reservoir without them such as the one on a 528e.

Adam
Yojedi
Posts: 143
Joined: Oct 18, 2016 1:42 AM
Location: Orange County, CA

Re: e28Goodies.com Brake Booster Upgrade

Post by Yojedi »

adam_poll wrote: Jan 15, 2021 5:18 PM This is the exact part I used as mentioned above, it's the high pressure line that goes directly from the pump to the steering box for a 528e. The original routing had a high pressure line from the pump to accumulator and then another down to the box.

https://www.rockauto.com/en/moreinfo.ph ... 2183&jsn=2
I'm not familiar with 528e engine bay. So I assume 528e and 535is have same PS pump placement?
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