Rear brakes in bad shape. Replace or upgrade?

[Vicleonardo1]

I was concerned about upgrading the rears to E21 drums and keeping the front stock. My mechanic who had done dozens wasn't concerned in the least. I really haven't found much bias at all with the change. But I haven't really done a full "Leonardo Lockup" test just yet. I am not running hard mountain roads or play much rally boy driving on the back roads so I haven't really put mine to the test. 

 

I figured the same as AVG, I would upgrade my front pads to some Porterfields first if I did experience a problem. 

I didn't have much of a problem getting new E21 drums and brake components from Rock Auto. Not expensive. 

 

But again, really didn't change much for me after doing it. I did feel better having fresh components put in. 

Edited May 10, 2020 by Vicleonardo1

[Son of Marty]

The real upgrade with the e21 brakes is you get rid of that damn w spring and the bleeding it causes?

[jimk]

17 hours ago, Vicleonardo1 said:

But I haven't really done a full "Leonardo Lockup" test just yet. I am not running hard mountain roads or play much rally boy driving on the back roads so I haven't really put mine to the test. 

You should take time to do it.  In an emergency you might have to brake hard and a surprise is not a good thing.

[Vicleonardo1]

12 hours ago, jimk said:

You should take time to do it.  In an emergency you might have to brake hard and a surprise is not a good thing.

Oh, I definitely plan on it. My car is in the shop more than I would like. Never felt safe enough on some of these roads near me to try it out (especially on wet pavement)- hey I live in Oregon and don't want to end up in a ditch, ravine, hazelnut orchard, pot farm (mind the booby traps), etc. 

If/when I get it back, I will give the pedal a stomp when I can. 

Edited May 12, 2020 by Vicleonardo1

[chargin]

On 5/9/2020 at 3:33 PM, Seth Horwitz said:

People spent a bunch of money (because over and above the brakes you had to get bigger wheels) just to get some red calipers. 

That's why it's so easy to find Red rattle can brake paint

 

On 5/10/2020 at 11:08 AM, jrhone said:

DONT upgrade to bigger rear brakes and not bigger fronts or you will lock the rears more easily and imagine stop on the brakes while cornering and the back locks up...not fun.

True?

 

That being said.....When I got my car +5 years ago it needed All Brakes redone. I replaced the Master with a cheap eBay replacement, rear cylinders with oem. My car was pulling to the right when braking, I then noticed I had 2 different calipers from "some" PO. With the cost of sourcing a matching pair of calipers I just paid the upcharge for the complete IE Volvo kit and Tii rear cylinders. A few weeks later I noticed the pedal still felt spongy, So I bled the brakes, then the next day I bled the brakes, then the next 3 days I bled the brakes, After shining a flash light into the booster I could see the new Master was leaking. I sourced out a Tii booster to get some extra engine clearance for the future (That's a different story) and ordered a new Tii Master for much more $$. I drove it for a few more months and wasn't happy with the "feel" on inspection I found one of my new rear cylinders had a very small leak, I could have warrantied it but decided the "RestoMod" gods had called me out so I purchased the rear Rabbit Kit from IE.

SOOO, after 4 years what do I think? Willwoods look cooler and may stop better but my Volvo/Rabbit/Tii master works REALLY well, I live next to the first freeway ever built in SoCal, this means I drive at 72mph and decelerate onto a 10mph offramp regularly so I get to Brake Check almost every day I drive the 02. 

 

Red Brake Rattle can used, stock vs Volvo:

 

Sourced Booster:

Rabbits on with new E-Brake cables:

 

 

 

 

 

[Einspritz]

I will speak in very general terms now as to optimize the brake system of your choosing involves much calculation involving an analysis of the hydraulic pressures F/R, the area and Mu of the pad and shoe material and a few other data points.

 

That said, BTDT with Volvo type calipers and 250mm rear drums from a 320i using off the shelf pads (Metal Masters) and generic shoes, and did find the rears lock up rather easily under hard braking. Never again.

 

Consider this discussion has not addressed that the 320I system, as with the E9 and Turbo used an automatic brake bias valve, seen here:

 

https://www.wallothnesch.com/en/pressure-valve-2002-turbo-you-need-1-for-1-car-34-17-09.html

 

Curious enough, the knee point is the same for all those cars.

 

or you can simply install an in line generic (e.g. Tilton or similar) adjustable valve in line to the rear.

 

Of note, is that the brake bias is partially dependent on the F/R weighting.....remember, BMW used a car with a full tank of gas, 4 people in the car, and "junk in the trunk" for their set up.

 

So, if you are running different to that, the bias will change, hence with an adjustable unit; you could change the knee point pressure to suit your driving needs. I'm not one that wants to bother with frequent changes for differences in street driving...too fiddly to calibrate.

 

I agree that the stock system is good enough for the street, but perhaps pads with a higher Mu AND at a low temperature and a higher Mu for the rears (IIRC generic Textar are at ~0.35 Mu or less) you can achieve "better than stock" without going down the rabbit hole of a BBK.

 

Porterfield makes some great compounds to fit the 2002.

 

Hope this provided some insight.

 

 

[chargin]

22 hours ago, Einspritz said:

or you can simply install an in line generic (e.g. Tilton or similar) adjustable valve in line to the rea

this may be a future project for me, thanks

[TobyB]

Quote

 using off the shelf pads (Metal Masters) 

 

So how did it work when you used actual brake pads, rather than metal pucks?

 

No, I take that back- if you install a metal bastard backwards, the steel backing plate has a higher coefficient of friction.

 

t

from experience.

[John_in_VA]

14 minutes ago, TobyB said:

So how did it work when you used actual brake pads, rather than metal pucks?

No, I take that back- if you install a metal bastard backwards, the steel backing plate has a higher coefficient of friction.

 

t

from experience.

Don't hold back - tell us how you really feel, Toby!!  ?

[Conserv]

31 minutes ago, TobyB said:

 

So how did it work when you used actual brake pads, rather than metal pucks?

 

No, I take that back- if you install a metal bastard backwards, the steel backing plate has a higher coefficient of friction.

 

t

from experience.

Ouch! 
 

[Vicleonardo1]

I got confused and painted my rear drums red..

Really didn't look cool at all.

[Vicleonardo1]

7 hours ago, TobyB said:

 

So how did it work when you used actual brake pads, rather than metal pucks?

 

No, I take that back- if you install a metal bastard backwards, the steel backing plate has a higher coefficient of friction.

 

t

from experience.

 

Good news: No Brake dust. 

Bad news: Sparks. 

[Einspritz]

I say "if you can't laugh with me, you can laugh at me"

 

This set up was recommended in the 1980s as an improvement over the stock Tii setup in the BMWCCA.

 

Remember those days? There were few options back then, and I took it that whomever "engineered" that system knew what they were doing.

 

When I observed the lock up condition, I thought who "engineered" that?

 

I then endeavored to understand braking systems by buying books, SAE papers, did the math by hand and then found software to do an analysis by weighing then dimensioning the car, noting such things as pedal leverage on the MC, MC diameters, system pressures, and the effects on the wheels given choices in pad and shoe material, sometimes calculating in the Mu of the tire's grip.

 

Done this for the E30 M3 as well.

 

Just getting the Mu curves of the pad and shoe materials is a chore as even to this day manufacturers don't want to tell, as it might divulge "the secret sauce"......and the marketing guys just want you to trust that they have the best thing for your needs. (Porterfield is the exception.)

 

Not so fast (or slow). Generally they aren't, as each car is different, weighting F/R is different, and the wants / needs / "feel of the car" to the driver are all different.

 

And, I have observed, that most wanting something different generally just want "a fix" and not to understand the whole ecosystem as it were, of the cars.

 

This holds true for other systems of our cars; the suspension, the steering, the injection system on Tiis and Turbos, electrical, etc.

 

i went through a similar time when I trusted that Steve Dinan sold "The One" suspension system ('spensive) upgrade for the 2002. He drove my car at a CCA track event and said "this drives like crap (it did), who put this together?"; to whit, I replied "you". When we arrived at the pits, he got out of the car and walked away. Nuf said.

 

That experience again endeavored me to learn about the suspension systems in the manner above to understand the dynamics of the car. Hours upon hours of learning, modeling, testing with more sophisticated software, a bit of data collection, and mentoring by some gifted automotive engineers. What I came up with was a system with springs unlike those offered by the "go fast" suppliers, Bilstein shocks valved to my specification and a few other minor mods that enable me to keep up with the more modern (OK '90s) M cars on the track and retain a comfortable ride on the street. It works for me.

 

The understanding of the Tii and Turbo injection systems and steering boxes followed a similar path. The electrical system is pretty easy- Volts and Ohms.

 

The fact is I now really don't implicitly trust that ANY "go fast" supplier knows their stuff, even Bilstein themselves notwithstanding (I argued with them for 6 months to get the shocks the way I wanted them, and even they didn't know their own shock rates for HD and Sport as comparison, HUH?). I would rather do the Math myself, and take the hit if I am wrong. If the supplier or FAQer can contribute their reasoning on why their system is great, with facts, then I'm all for that; we can then discuss the merits.

 

Finally, i am not one to tell you what is best, but offer my opinions on this FAQ what you should consider; the best is what works best for you.

 

Glad to have been a source of humor to you all, we need more of that!