Brake Upgrades

[erzengel13]

Just a quick question. Well, not quick, but I was wondering? What are my options as far as upgrading the front brake calipers and rotors. I have a 1980 320i and I'm in need of some vented and gas slotted rotors with some bigger calipers. Now jcrook, I understand you used the Volvo 4 pot calipers, but what kind of rotors? Are they an upgraded version of the 77 rotors, or are they Volvo as well? And what it needed for doing the rear conversion from drum to disc? Any and all info will be much appriciated.

Matt

[jbob]

you use the 77 vented-rotors w/ the volvo 4-piston calipers.

for rear discs, you can either get 323i rear trailing arms, discs, & calipers (i've read that E30 rear disc brakes are an upgrade that fit on 323i rear trailing arms). or www.2002parts.com (Aardvarc Racing) sells rear disc kits that utilize the existing trailing arms.

IMO, w/ volvo-4pots, E12 master cylinder, axxis ultimate pads, & velvatouch rear shoes, the car stops really well. i'd only switch to a rear disc setup to shed some unsprung weight.

[jrcook320]

Ditto, I used the stock '77 rotors. I slotted the calipers 6-7mm so they would mount closer to the hub and contact more of the rotor. Someday I'd like have someone make me some floating rotors that are 14mm larger dia. so I can push my calipers all the way out.

I'm sure you've probably seen these posts, but here they are just in case:

Big brake writup

Proportioning valve

Edit: For rear brakes you may seriously want to look at the Aardvark setup. I went with used 323i stuff (over $200 on ebay) and didn't get so lucky. The rear parking brake assy's were total junk (over $150 just to replace the shoes and hardware), bearings were shot (another $120), calipers needed rebuilt ($30), and on top of all that, I had a bent stub axle. I found another 323i trailing arm with no caliper at a bmw scrap yard ($100 - I got raped but was desperate) and it ended up having a bent stub axle too, so I ended up buying a new axle and drive flange from Walloth & Nesch ($250). I would have been way ahead to go with the Aardvark setup.

[kdanielson]

Do you really NEED better brakes or are you going for the wow factor?? I run '77 vented rotors with stock calipers, Porterfield R4S carbon kevlar pads and stainless hoses-rear brakes are stock drums. This set up works VERY well at reasonable cost. The best rear upgrade is shoes redone with the R4S material, Porterfield will do that for you. Unless you are racing that's all you really need.

Having said that, I have some 323i rear trailing arms that will get a caliper upgrade.... the stock 323i rear calipers are patheticaly small-"toy like" is the best description I can come up with. I will use a set of Acura calipers with the parking brake built in along with e30 disks. Why, because I like to fab stuff...

ken

[jjgbmw323]

Do you really NEED better brakes or are you going for the wow factor?? I run '77 vented rotors with stock calipers, Porterfield R4S carbon kevlar pads and stainless hoses-rear brakes are stock drums. This set up works VERY well at reasonable cost. The best rear upgrade is shoes redone with the R4S material, Porterfield will do that for you. Unless you are racing that's all you really need.

Having said that, I have some 323i rear trailing arms that will get a caliper upgrade.... the stock 323i rear calipers are patheticaly small-"toy like" is the best description I can come up with. I will use a set of Acura calipers with the parking brake built in along with e30 disks. Why, because I like to fab stuff...

ken

What year acura calipers for the rear - and how are they different from 325i ones.

I have an upgraded set of front calipers that are ready to go on..when ever my car is done.

[kdanielson]

The rear calipers I have are from a middle '90s Acura. They are a single piston sliding caliper. They will require a custom mount and adapting to the parking brake cable.

ken

[jjgbmw323]

The rear calipers I have are from a middle '90s Acura. They are a single piston sliding caliper. They will require a custom mount and adapting to the parking brake cable.

ken

Hi Ken,
I go to the salvage yards all the time - so what model acura?
What is the advantage of using this over 325i calipers or the 323i ones.

And can you post pictures of the proceedure;
thanks
J

[Helmetboy]

There is a guy on Roadfly selling bbk's for 2002's, they look really nice too. You may want to run a search in the 2002 section for them.

[Madhatter]

If you plan any form of real racing the volvo setup wont hold up.

[jrcook320]

If you plan any form of real racing the volvo setup wont hold up.

Based on _____? They'll work far better than the factory setup.

[Al Canuck]

If you plan any form of real racing the volvo setup wont hold up.

That's a very odd statement.

[RDAvena]

Based on _____? They'll work far better than the factory setup.

I am curious as well.

I have the same set up and have run quite a few hot laps in the car and the calipers have yet to reduce in performance like the stock 323i calipers.

Inquiring minds want to know....

[Madhatter]

Based on _____? They'll work far better than the factory setup.

2 laps before the pedal went to the floor Kinda scary heading down a straight at 200km/h into a fast sweeping right hander with a massive sand trap that is known to roll cars staring right at you. Go to grab the brakes and find understeer then no brakes at all

Much better than the stock setup for street use, if you plan to track the car you wont survive more than a few laps. There simply isnt enough surface area to provide efficient, prolonged braking.

[blitzed310]

Much better than the stock setup for street use, if you plan to track the car you wont survive more than a few laps. There simply isnt enough surface area to provide efficient, prolonged braking.

Is it possible you didnt have the correct pads for the situation? Or is it possible you boiled the fluid due to the wrong fluid for the circumstances? Is it possible that you dont have SS brake lines?

Or did you have all of the above? What pads were you using?

[Madhatter]

Lets see.

Mintex pads (m1144 compound). castrol stuff. And yes, it had braided lines Maybe you guys arent going fast enough

[jbob]

I put on 160 minutes of track time on the volvo calipers over a weekend (track temperatures were from 80 to +120 degrees), and had no problem w/ the brakes whatsoever. This 1.5 mile track only has 4 brake zones for my car, 3 of which i really had to hammer down on the brake pedal (locked it up a couple times trying to go deep into this sharp hairpin). There was a hint of brake fade on the last run of both days, but i'm putting that blame on the brake pads (PBR deluxe @ the time).

[Madhatter]

only 4 and 1.5 miles? thats a pretty basic circuit

[jbob]

it is a pretty basic circuit....uses 1/2 of a nascar oval, tho the infield is a bit more technical: decreasing radius U-turn, into a few chicanes, to a mini 'carousel', then a sharp hairpin back onto the nascar oval.

but the volvo calipers get my approval for future track use.....they did hold up fine for 160 minutes of track time (roughly 120 laps) on a couple of pretty hot days (the air reached just over 100 degrees).
by the end of each day, i had about a 1/2 tank of gas to fill & some partially melted tires

[RDAvena]

if you plan to track the car you wont survive more than a few laps. There simply isnt enough surface area to provide efficient, prolonged braking.

Comparing the pads side by side there is definately more than enough surface area:



couple this with the added mass of the calipers. And I was using the cheap Metal Masters pads not some special race composite.

[jjgbmw323]

only 4 and 1.5 miles? thats a pretty basic circuit

I have the so called "hartge" really volvo 4 piston calipers.
I got them - from a german seller..

How are wildwoods..I think they can be adapted to fit 15 inch rims..

[Madhatter]

Comparing the pads side by side there is definately more than enough surface area:



couple this with the added mass of the calipers. And I was using the cheap Metal Masters pads not some special race composite.

Errr, no, All you have done is increased the size of the pad while running stock rotors. You need to increase the surface area of the rotor to increase heat dissipation, increasing surface area of the pad without increasing radial height does nothing for cooling.

Either you increase the thickeness, you increase the diameter and/or you increase the radial area of the pad. None of this has happened, the rotors are stock, the pad has an almost identical radial area compared to the standard pads, from a cooling stand point, nothing has changed except when you changed the fluid. The only differnce is the pad compound has a higher temperature range where it can still maintain good friction with the surface of the rotor. Exceed the temp between frictional surfaces, the pad compound is essentially rendered useless and braking ability deminishes very quickly.

Without increasing any of the above so you suffer the same problems encountered with the stock setup. If you do any serious racing you will 1) crack/ "warp" (suffer from DTV actually) the rotor 2) boil the fluid as they dont cool very well, they retain massive amounts of heat for long periods of time.

The only thing saving you from experience braking problems is the higher boil point of the better quality brake fluid and the higher temp range of the pad frictional material. Go to a different circuit with sharper, low speed corners following long straights and you will see the short comings the setup has. Deep, prolonged braking = big trouble when racing the volvo setup.

[jjgbmw323]

Errr, no, All you have done is increased the size of the pad while running stock rotors. You need to increase the surface area of the rotor to increase heat dissipation, increasing surface area of the pad without increasing radial height does nothing for cooling.

Either you increase the thickeness, you increase the diameter and/or you increase the radial area of the pad. None of this has happened, the rotors are stock, the pad has an almost identical radial area compared to the standard pads, from a cooling stand point, nothing has changed except when you changed the fluid. The only differnce is the pad compound has a higher temperature range where it can still maintain good friction with the surface of the rotor. Exceed the temp between frictional surfaces, the pad compound is essentially rendered useless and braking ability deminishes very quickly.

Without increasing any of the above so you suffer the same problems encountered with the stock setup. If you do any serious racing you will 1) crack/ "warp" (suffer from DTV actually) the rotor 2) boil the fluid as they dont cool very well, they retain massive amounts of heat for long periods of time.

The only thing saving you from experience braking problems is the higher boil point of the better quality brake fluid and the higher temp range of the pad frictional material. Go to a different circuit with sharper, low speed corners following long straights and you will see the short comings the setup has. Deep, prolonged braking = big trouble when racing the volvo setup.

So I am unclear what you are saying - Matthatter? Do You mean that in addition to the 4 pot upgrade in caliper to Volvo ones, and larger brake pads, you need to get a Larger rotor to brake better?

I have thought of this, its just I dont drive my 323i so I dont brake right now either.

Matt on the e21 email digest uses Coleman racing two piece rotors, and wildwood brakes. The main problem: How large can u make the rotors with 15inch rims?

According to Matt - who has the designs of several rotors - you have your work cut out for you..running 15 x6.5 BBS front rims and making massive brake/rotor combinatins fit.

FYI while we are on the subject of brake upgrades.. Pete - aka - Redmist has talked in the past about fabbing out of alliumiun the mounting brackets to adapt wildwoods to the e21 spindle.

[RDAvena]

Errr, no, All you have done is increased the size of the pad while running stock rotors.

True, this is all that I have done. Still driving with the stock rotors although the calipers have been modified so that all of the pad area is contacting the rotor. I have driven(hard), a 2.4 mile course as you had described with all of the deep braking ect, even with the pads boiling smoke at the end of the session and still have yet to come across your type of experience.

Guess the saying is true: "What works for some does not work for others", but I seriously doubt a blanket statment of that "they all do not work" would be justified by one expirience.

See, now you went and scared Joe ...he is going to have to start reciting "Who's on first"

[jrcook320]

Errr, no, All you have done is increased the size of the pad while running stock rotors. You need to increase the surface area of the rotor to increase heat dissipation, increasing surface area of the pad without increasing radial height does nothing for cooling.

Either you increase the thickeness, you increase the diameter and/or you increase the radial area of the pad. None of this has happened, the rotors are stock, the pad has an almost identical radial area compared to the standard pads, from a cooling stand point, nothing has changed except when you changed the fluid. The only differnce is the pad compound has a higher temperature range where it can still maintain good friction with the surface of the rotor. Exceed the temp between frictional surfaces, the pad compound is essentially rendered useless and braking ability deminishes very quickly.

Without increasing any of the above so you suffer the same problems encountered with the stock setup. If you do any serious racing you will 1) crack/ "warp" (suffer from DTV actually) the rotor 2) boil the fluid as they dont cool very well, they retain massive amounts of heat for long periods of time.

The only thing saving you from experience braking problems is the higher boil point of the better quality brake fluid and the higher temp range of the pad frictional material. Go to a different circuit with sharper, low speed corners following long straights and you will see the short comings the setup has.
Deep, prolonged braking = big trouble when racing the volvo setup.

Makes perfect sense. In laymens terms, the diameter of the rotor has a greater effect on stopping power than the surface area of the pad. Since everyone is using the stock rotor, the "radial area" is the same. Put a larger pad on the stock rotor and the rotor will get too hot and warp. This does increase the friction available for this rotor size, but friction=heat. Put a smaller pad on huge rotor and the pad material will get too hot. A larger rotor basically gives the pad a larger "moment arm" (like a cheater bar on a wrench), but to take advantage of this, or for the pad to be as effective when it's spaced out further, the pad surface area will also need to be increased. I still think the volvo setup is the biggest bang for the buck as far as breaks for the E21. Plus, the volvo calipers will fit over a rotor that is 14mm larger than the stock rotor, if you can find a supplier.

[blitzed310]

You could always cut a hole in the floor board and use the tried and trued method of Barney Rubble. You dont even have to worry about boiling the fluid, and if you have a passenger you got instant tractor brakes, BooYaa!