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Old 05-30-2017, 06:21 PM   #1
CMG
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Daily Driver E30 Sedan w/ M50...Practicality of 5 Lug Swap?

I basically have lots of bimmers and lots of parts and trying to set up my latest acquisition to be my daily driver. It's a 1989 BMW 325i w/ 1993 M50 swap. Right now it has the E21 brake booster with stock brakes and a z3 steering rack. It uses the stock suspension with Ground Control conversion coilovers. I need to refresh all the suspension and wheel bearings and add reinforcement tabs, and I already have most of the necessary E36 parts for the conversion, and I have multiple 5x120 wheel sets, so that is why I am considering swapping. The lack of wheel options does suck, but my main thing is wanting better braking. I'm all about performance, but keeping this car mild and going for practicality and reliability. Some of the questions I had were:

-What options are there for just a better bolt on stock 4 lug brake set up (including booster/BMC)?

-Right now I have zero rub lock to lock using 15x8 and 195 tires, will using bigger wheels with smaller sidewalls and the z3 rack most likely rub at full lock or rolled fender?

-I read that the z3 rear hub is a direct bolt on for 5 lug in the rear, but that it extends out slightly farther, is this correct? Is the e36 318ti considered the "proper" way to do the rear. I want to retain e-brake.
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Old 06-10-2017, 02:57 PM   #2
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Never mind. I've been looking into it and just gonna keep stock brakes and 4 lug and look into a better booster/cylinder set up. The stock E30 brakes are more than sufficient for normal use, and 5 lug costs more to install and to maintain in the long run.
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Old 06-12-2017, 11:43 AM   #3
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5 lug really messes with suspension geometry (offsets specifically) too unless you do the E30 M3 route.
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Old 06-12-2017, 07:12 PM   #4
CMG
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Yeah the only benefit I saw was for better wheel selection, and bigger wheels are required to clear brakes anyways. I actually have a complete e30 m3 suspension, but it's a spare for the other cars. Been looking into ways to improve brake pedal feel but seems like it's pretty pricey.

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5 lug really messes with suspension geometry (offsets specifically) too unless you do the E30 M3 route.
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Old 06-12-2017, 07:33 PM   #5
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I don't know anything about the e21 booster, but pad material has a big effect on braking in general. What pads are you using and what are you trying to improve?
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Old 06-12-2017, 10:38 PM   #6
CMG
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The problem is not the pads or discs, it is the pedal feel due to the E21 booster (and I believe 325ix BMC?) required for the m50 swap. It works fine, but you have to push down halfway to engage and it's kind of a vague feeling, you can't really feel the pads bite. It's basically something that you can get used to if you drive it regularly, but if you just jumped into it and drive it you would notice it. Only other possibility I can think of is that the BMC has to have the shaft cut and modified to fit, so maybe it can be cut a little shorter or adjusted some.
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Old 06-13-2017, 04:10 AM   #7
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Booster has an effect on pedal effort, not throw, what you're describing could be caused by poorly adjusted clevis or maybe improperly bled brakes. I have an e21 booster on my racecar and it feels pretty good, but I have a big master cylinder and e46 m3/325i brakes with race pads... Not sure how it would feel on the street with less-bite in the pads.

I think for a street-only car, e36 m3/Z3 stuff is the way to go. For a track car, I don't like the geometry changes you end up with in the front. E30 M3 is the way to go for sure, but the sleeve kits people are selling now are kind of a happy medium. You lose some offset in the front and end up somewhere in between e30 m3 and e36 m3 stuff, but you still use all e30 components.
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Old 06-13-2017, 12:02 PM   #8
earthwormjim
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Quote:
Originally Posted by CMG View Post
The problem is not the pads or discs, it is the pedal feel due to the E21 booster (and I believe 325ix BMC?) required for the m50 swap. It works fine, but you have to push down halfway to engage and it's kind of a vague feeling, you can't really feel the pads bite. It's basically something that you can get used to if you drive it regularly, but if you just jumped into it and drive it you would notice it. Only other possibility I can think of is that the BMC has to have the shaft cut and modified to fit, so maybe it can be cut a little shorter or adjusted some.
I thought you could fit the stock booster by redrilling holes and shifting it over a bit?
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Old 06-14-2017, 06:15 AM   #9
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the 325ix master cylinder is exactly the same size as the RWD cars, it just has a different bolt pattern. And the ix booster actually has more chamber volume IIRC. Maybe the E21 booster is too small.
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Old 06-14-2017, 10:40 AM   #10
CMG
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I was recalling off the top of my head the parts used when doing an M50 swap. I believe it's the E21 booster and 325ix BMC that has the shaft cut and re-threaded to make it shorter. JB, you might be on to something, I was planning on checking the adjustment. When you say you are using the bigger brakes that is with 5 lug, correct? I read that there were no bolt on big brake upgrades for stock e30 4 lug. I have multiple BMWs so I can really tell the difference in pedal feel, especially compared to E30 M3 and E36 M3. The pads bite fine, I just have to push harder and further in than I would normally expect, and there is not as much resistance pushing back. The car has an ABS system, but I have yet to get to the point of it engaging. Could the ABS being non-functional be part of the problem and how would I check that?
FYI there is a OEM BMC upgrade for the E30 M3, I believe it is from an E31 850i, much bigger cylinder, and direct bolt on. Anybody know if there are difference between the E30 M3 booster and BMC and non M3?
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Old 06-21-2017, 09:57 PM   #11
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http://www.massivebrakes.com/brake-systems.php

Brake upgrades for 4lug...
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Old 06-22-2017, 06:19 AM   #12
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Quote:
Originally Posted by CMG View Post
The problem is not the pads or discs, it is the pedal feel due to the E21 booster (and I believe 325ix BMC?) required for the m50 swap. It works fine, but you have to push down halfway to engage and it's kind of a vague feeling, you can't really feel the pads bite. It's basically something that you can get used to if you drive it regularly, but if you just jumped into it and drive it you would notice it. Only other possibility I can think of is that the BMC has to have the shaft cut and modified to fit, so maybe it can be cut a little shorter or adjusted some.


I have thought about doing the E32 Master Cylinder upgrade to my car. It is a direct bolt on for the M20 however, I came across this thread awhile ago which notes you can use the E32 MC and brake booster with a little modification (a remote reservoir) with DOHC swapped cars.
http://www.r3vlimited.com/board/showthread.php?t=274637
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Last edited by Zeemz; 06-22-2017 at 06:41 AM.
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Old 06-24-2017, 04:39 PM   #13
CMG
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The main issue with M50 swaps is booster clearance to intake manifold, and I'm pretty sure my car has the '88 325ix booster. The E32 BMC is pretty much bolt on to all E30 boosters except for ix, making it that much more complicated to swap in the right components.
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Old 07-30-2017, 06:55 AM   #14
Brian697
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I was looking for a "firmer" pedal so I installed the e38 master cylinder when I did my s52 swap (and moved stock booster over .5").

As has been noted by others, it resulted in a much firmer feel, but the effort to get the same braking results went up considerably.

At some point, I will probably change back to the stock master cylinder.

Edit: from e32, not e38

Last edited by Brian697; 07-31-2017 at 07:18 AM. Reason: Correct error
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Old 07-30-2017, 10:41 AM   #15
CMG
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Yeah as I've driven the car more I've gotten used to it. I'm pretty sure the ABS is not working on the car. The feel is different, but still sufficient.
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