An E21 I3MW rustoration

[HappyE21]

I think if I was to bolt it in I would have to drill holes in the rear strut towers, probably not too big of a deal, or I’ll just get a shop to weld it in real quick. So if I’m not mistaken, you just have to run a positive from the battery to the alternator and the fuse box and then ground it in the trunk?

TEP sells a battery cutoff switch with the kit so it that what you mean by circuit protection? I think the whole kit comes with the tray/brace, wiring and the switch for something like $250.

[I3MW]

I think if I was to bolt it in I would have to drill holes in the rear strut towers, probably not too big of a deal, or I’ll just get a shop to weld it in real quick. So if I’m not mistaken, you just have to run a positive from the battery to the alternator and the fuse box and then ground it in the trunk?

TEP sells a battery cutoff switch with the kit so it that what you mean by circuit protection? I think the whole kit comes with the tray/brace, wiring and the switch for something like $250.

Correct, there were two bolt holes on each side. Center punch and a drill should do the trick. I remember reading that some people were fighting to get the nut and bolt threaded with the rear struts on but I think they got it done and worse case dropping the struts to get your hand in there isn't too bad.

As far as wiring goes. Yeah you need one real beefy wire going up the alternator. I snaked mine behind the rear strut tower on the passenger side, down between the rear seat and the door card, underneath the carpet and out through a pass through on the passenger side. I also ran a separate skinny wire from the battery right to the fuse box but you could just have the skinny wire starting at the alternator and go to said fuse box.

I did two separate wires because I think it provides more specific circuit protection. Meaning I have a smaller fuse on my skinny wire that should never blow (unless there is a real issue) and I have a relay on the beefy wire that could/should trip if I ran the starter for a long time. That's really the only way to protect that beefy wire because starting the car is basically a short circuit for a few seconds.

[HappyE21]

Ok, thanks for the good info. I will let you know how it goes once I do it.

what’s the next project on your build?

[I3MW]

Ok, thanks for the good info. I will let you know how it goes once I do it.

what’s the next project on your build?

Sounds good, yeah keep me posted.

Right now my car looks like this:

end.jpg

This is because, between the banged up fender on the passenger side and my bumper being eroded at the corners I decided to get a straight fender and add metal to my existing bumper. You may recall I did shaved the bumper a while back. It came out fine but I didn't add metal to the corners. I don't know if the corners are supposed to be that way because the rubber trim covers that part or if mine rusted away (probably both) but I decided to finish where I left off.

Anyway, very time consuming but hopefully worth it:

metal weld PS.jpg

PS metal.jpg

DS metal origin fit.jpg

DS metal.jpg

[I3MW]

bondo early 2.jpg

bumper bondo.jpg

body finish.jpg

body finish 3.jpg

bumper prime 2.jpg

So that's that, I'm sending it to a body shop for paint in about a week

[HappyE21]

I just repainted my bumper, it’s really not in the best shape but it’s a lot better than it was before.
1B0AB087-E2CA-472D-B594-5CF3A601CFED.jpeg81027D36-6E52-4277-BA3F-DF099FDEAEF9.jpg58B0C109-F234-463F-8ACE-C5B0571EDADB.jpg

[I3MW]

Not bad, the lower portion would benefit from some bondo but other than that looks p good.

My car is at the body shop now, so lets keep our fingers crossed but I do have some more updates from this winter. I decided to dye my headliner with out removing it It's certainly not ideal but the off white really highlighted the stains and discoloration that have accrued over the decades. I think it will tie the interior together well, especially since I want to change to a black carpet.

As a sanity check, I dyed the sunroof panel first, then gave myself the green light. Masking things off and prep work is going to be key to offset the fact that I cant remove the headliner out of the car atm. I did remove the rear seats and shelf that holds the speakers. And any little handle, screw, rear view mirror etc. make sure the vinyl is as clean as possible before starting.


headliner prep 2.jpg

headliner prep 3.jpg

I'm only now realizing how bad I've been about taking pictures. Just been having a lot going on and running around like chicken with my head cut off. This turned out pretty good. Just about how I thought it would maybe even a little better. Worth doing to visualize what I want the interior to look like. The prep work I did was very tedious but totally worth it. I will take some more pictures when I get the car back.

cordovan headliner.jpg

[I3MW]

Story time: you may have read that my rear seats never seemed to fit quite right. Only to discover that they are probably E30 seats so when an E21 finally popped up at the "near" by junkyard I jumped on it. RIP poor E21. I should've been better equipped for the excursion but pick and pulls are basically non existent near me. OF COURSE the E21 was about as far away from the entrance as possible and it had rained quite hard for the past two days:

junky.jpg

So yeah furthest away, walk through the mud, and then try to play temple of doom getting into the car without getting my sneakers soaked.

junk close.jpg

Rear seat came out easy. This car was DISGUSTING.

jiunk un.jpg

Huge shout out to the other E21 enthusiast who showed up while I was trying to get upper portion out without a drill. At first I thought we were going to have a stand off but we both wanted different parts so we got along. I tried to convince him to join the forum, I think the forums reputation proceeds us but I swore the E21 section is just like 12 people who at least know ass from our elbows.

Anyway after sterilizing and fumigating the hell out of theses seats, I move on to color matching. Finally this interior is coming together. I still have a few tricks up my sleeve.

E21 rear seat tan.jpg

e21 rear seat diy.jpg

[I3MW]

21 bench partial.jpg

21 bench full.jpg

These went in after I dyed the headliner. I also painted the metal portion of the e-brake the same color brown. I think it was a nice touch. I'll have to get more pictures.

int w new rear seat.jpg

[HappyE21]

Seats look great! That black headliner is really the icing on the cake, may have to do that some day.

[I3MW]

Seats look great! That black headliner is really the icing on the cake, may have to do that some day.

Thanks! The headliner and sun visors are actually brown, exact same color as the seats. The side pieces down the front windshield stayed OEM black. I left the sunroof crank and grab handles factory black as well. I'll take better pictures shortly!

[I3MW]

She's back:

new f.jpg


frwash.jpg


Before:

raw bumper.jpg








After (disregard all the dust on the hood, this was before the car wash):

othersideclose.jpg

[I3MW]

So I'm almost there. Car drive great except the BRAKES. I noticed this after I bled the system for the new clutch slave. It seemed to be leaking and fluid had been disappearing prior to the install but brakes had always been good prior as well. The system appears to be designed such that the clutch hydraulics will get low on fluid before the brakes. Kind like how on my subaru wagon you know winshield washer fluid is low when the rear wiper has no more fluid but the fronts still spray. Anyway. After the new clutch cylinder and power bleeding the clutch setup feels great. But it looked like 10-15 PSI on the motive power bleed caused the brake master cylinder to leak - fluid dripping out where the BMC bolts to the booster (near the firewall). So ok I thought lets get a new BMC, seems easy enough (spoiler alert, I've never done one). Removal is easy but slow for me. A few locations I could get a socket with an extension but most places I needed a box wrench (my ratcheting ones wouldn't fit either). Got it off, decided to clean and paint this rusty bracket. And chase all the threads on everything. M10 and M8 IIRC.

bracket.jpg


paintbr.jpg

Now take a look at the old and new BMCs:

cylindercomp.jpg

See how the old one has a "thread adapter" on it. In my infinite wisdom I assumed the PO had done another stupid think and hard to repair threads or something. I was wrong about that, more on this later.

Installing the BMC went pretty quick (because I missed the memo about bench bleeding) but I figured it out pretty quick once I tested the pedal and it was even worse than before. I then proceeded pressure bleed the system both by first cracking open the hard brake line connections right at the BMC and then power bleeding the connections at each brake drum and caliper (Rear PS, Rear DS, PS, DS last). No bubbles from the calipers/drums but overall it was a noticeable improvement. But pedal feel still kinda sucks. I repeated this a bunch, pumping the brakes etc. Nothing, at this point the pedal feel is what it is. The car stops ok but I can no longer lock up the brakes and there is more pedal travel before engagement.

I started to suspect that the "thread adapter" was in fact a proportioning valve. Sure looks like it:

brake val.jpg

Now here's the problem. That thread is larger than the brake line thread and therefore won't screw on to my new BMC. When I google "Brake Proportioning Valve" for our E21s, something totally different comes up. SO can anyone shed some light? I really can't find any info on this. It appears I got the "right" BMC or at least the common one for our cars. The only place I could find one that looks right is ebay:

https://www.ebay.com/itm/40360970096...4AAOSwGzJiXVX5

and I don't even know if that will solve my problem? Feel free to chime in!

[jakub421]

It's not a proportioning valve, its actually a "residual check valve".

They make a bunch of these that you can put inline with your rear brake line if you can't find one that screws in to the master cylinder.

[I3MW]

It's not a proportioning valve, its actually a "residual check valve".

They make a bunch of these that you can put inline with your rear brake line if you can't find one that screws in to the master cylinder.

Thanks, I was able to at least find information regarding the topic by searching for that. Still not a lot of documentation surrounding our cars. It sounds like it's often used with rear drum brakes to provide "better feel" and decrease pedal travel. I see a lot of 2002 guys that say you don't need to use it when they retrofit our brakes.

I just bought the BCM in the link above. I'm going to swap the whole thing and see if that makes a difference.

[I3MW]

So I haven’t been able to find a solution to this residual check valve problem. I doubt I can source the correct BRake Master Cylinder so I think I have three options:

1. Rebuild my old BMC and use the existing Residual Check Valve.

2. Just convert the drums to caliper earlier than I had planned and budgeted.

3. Retrofit an RCV to my current setup.

I think option 3 makes the most sense but I need some help. Research indicates that there isn’t a good adapter for the OEM RCV to this other style of BCM, and even if I could adapt it I doubt it would fit without fabrication/cutting the brake lines. Can anyone confirm if the RCV is 2 or 10 psi? Anyone have advice? There’s not a lot of room to piggy back what I believe would be an M6 threaded RCV to the existing brake line. don’t know how I’m going to do it without fabricating a new brake line which seems like a big hassle, at that point I’m like should I just do the GTI REAR calipers?! I’m going to start researching how to rebuild the BMC, maybe that’s the move?

[Clio320i]

Based on what these guys are saying, it sounds like it's 10psi (have you seen this thread?) https://www.bimmerforums.com/forum/s...pressure-valve

Wish I had advice. Can't remember when my BMC was new but it's Ate brand, and it has that valve on it. Doesn't seem like those are available anymore aside from that Ebay one you found. What happened when you installed that?

[I3MW]

Thanks, I did see that thread. I thought I’ve also seen 2psi mentioned else where but 10psi seems to be more common. But yeah the BMC that I showed from eBay showed up and was not the one they pictured. It was all M6 ports, wouldn’t work with the RCV. I’m going to return it. Perhaps I’ll give it one more go, and seek out an ATE BMC.

heres a picture of the 2nd one I bought, looks like everyone has the same supplier:

455C03AF-E04B-409F-B613-756A9C6FB354.jpg

[Clio320i]

Every single BMC I'm seeing anywhere seems to lack that valve (realoem calls it a "pre-pressure valve"). That said, seems to me all the parts houses are listing P/N 34311120032. So I guess you could try the other P/N which is 34311151850? I found this: https://www.ebay.com/itm/224935653252. That one has a circle with the number 10 in it just like yours.. so maybe?

BTW I'm super inspired by your thread, particularly the rust repair. I have a zypressengrun car as well and it's pretty dang rusty, and I'm hoping to get started on some rust work this year.

Oh hey, do you know if that black E21 is still lurking in the boneyard? Maybe it has something you could use...

[I3MW]

Every single BMC I'm seeing anywhere seems to lack that valve (realoem calls it a "pre-pressure valve"). That said, seems to me all the parts houses are listing P/N 34311120032. So I guess you could try the other P/N which is 34311151850? I found this: https://www.ebay.com/itm/224935653252. That one has a circle with the number 10 in it just like yours.. so maybe?

BTW I'm super inspired by your thread, particularly the rust repair. I have a zypressengrun car as well and it's pretty dang rusty, and I'm hoping to get started on some rust work this year.

Oh hey, do you know if that black E21 is still lurking in the boneyard? Maybe it has something you could use...

Great suggestion, I'm going to give this one more try and buy 34311151850.

Thank you for the kind words, always happy to hear someone benefiting from this thread! Zypressengrun is a pretty cool color and in my opinion worth restoring.

[okieflats]

My car does not have one of those residual check valves; so I'd say you don't need it. I gather it keeps the pressure to the rear drums at 10 psi minimum, even after you let your foot off the brake pedal. The pressure to the front calipers goes to zero, but the pressure to the rear drums drops to 10 psi and doesn't drop below that.

I could be wrong about that.

Anyway you have some other problem, either trapped air or too much slack in the brakes. Rear brake shoes not adjusting, not close enough to the drum, so they have to move too much before making contact, so makes for too much pedal travel, and feels soft.

Switching rear drums to calipers is not the answer to this. It should be simple to fix once you figure out what needs to be done.

[okieflats]

What is a residual valve?

Definition & Description
A Residual Pressure Valve is a special type of one-way check valve. They are used to keep a small amount of pressure in the brake lines. This helps the brakes engage more quickly and reduces pedal travel.

There are 2 basic types of residual valves, 10-psi and 2-psi.

How are they used?
A 10-psi Residual Valve is used with drum brakes. The valve holds 10 psi in the brake lines going to the wheel cylinders. This keeps pressure against the return springs inside the drum. This means the brakes engage faster with less pedal travel.

Most disc brake systems do not require a residual valve. However, a 2-psi Residual Valve is used when the master cylinder is lower than the calipers.

When the master cylinder is mounted on the firewall, it is usually higher than the calipers. Gravity keeps the fluid from flowing backwards. In this case, a residual valve is not required.

In some vehicles, the master cylinder is relocated to a lower position. This could be under the floor or on the frame rail. In this design, a residual valve is required to prevent fluid back-flow. Without a residual valve, the pedal could feel “spongy.” It would also take more pedal travel to move enough fluid to engage the brakes.

Notes
When converting from drum to disc brakes, remove the 10-psi valve.
The constant line pressure causes the brakes to drag.
This will cause overheating and premature wear.



https://help.summitracing.com/app/an...idual-valve%3F

[I3MW]

My car does not have one of those residual check valves; so I'd say you don't need it. I gather it keeps the pressure to the rear drums at 10 psi minimum, even after you let your foot off the brake pedal. The pressure to the front calipers goes to zero, but the pressure to the rear drums drops to 10 psi and doesn't drop below that.

I could be wrong about that.

Anyway you have some other problem, either trapped air or too much slack in the brakes. Rear brake shoes not adjusting, not close enough to the drum, so they have to move too much before making contact, so makes for too much pedal travel, and feels soft.

Switching rear drums to calipers is not the answer to this. It should be simple to fix once you figure out what needs to be done.

Yeah I agree switching to calipers is not the answer but it is on the to do list lol. But for now the simplest solution would be my first choice. All I know is the brakes worked well before I did the clutch job. Power bled the system to get air out of the new clutch slave and suspected a leak from the master cylinder (as well as the old clutch slave). I think that is what caused the clutch/TOB issues in the first place. Now my brake pedal feel is worse (clutch pedal and trans feel great btw) despite bleeding the entire system, and not even seeing a single bubble from any of the calipers, just straight fluid.

What is a residual valve?

Definition & Description
A Residual Pressure Valve is a special type of one-way check valve. They are used to keep a small amount of pressure in the brake lines. This helps the brakes engage more quickly and reduces pedal travel.

There are 2 basic types of residual valves, 10-psi and 2-psi.

How are they used?
A 10-psi Residual Valve is used with drum brakes. The valve holds 10 psi in the brake lines going to the wheel cylinders. This keeps pressure against the return springs inside the drum. This means the brakes engage faster with less pedal travel.

Most disc brake systems do not require a residual valve. However, a 2-psi Residual Valve is used when the master cylinder is lower than the calipers.

When the master cylinder is mounted on the firewall, it is usually higher than the calipers. Gravity keeps the fluid from flowing backwards. In this case, a residual valve is not required.

In some vehicles, the master cylinder is relocated to a lower position. This could be under the floor or on the frame rail. In this design, a residual valve is required to prevent fluid back-flow. Without a residual valve, the pedal could feel “spongy.” It would also take more pedal travel to move enough fluid to engage the brakes.

Notes
When converting from drum to disc brakes, remove the 10-psi valve.
The constant line pressure causes the brakes to drag.
This will cause overheating and premature wear.



https://help.summitracing.com/app/an...idual-valve%3F

This is a great, succinct, answer.

[I3MW]

So the other part showed up and... no dice all m6 ports. I realized there's a fourth option. I can try to just drill out the port to M8. It seems kind of sketch but should actually be pretty easy? I will probably give that a shot, but if you think that's a terrible idea, I'm all ears.

[jakub421]

At this point I would just splice the 10 psi residual pressure valve into the drum brake line...
You can install it pretty much anywhere between the rear before the two lines split off and the master cylinder.