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Front to rear brake bias question


schwarz75
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My '73 2002 has Volvo front calipers with vented '77 E21 320i rotors, and E21 320i rear 250mm drums. Currently I have 185/70-13 Yokohama T-4 tires.

On hard braking the front brakes are more powerful than the rears. I know that matching disc brakes with drum brakes is not ideal, but I don't want to upgrade to discs in the rear.

What is the best way to improve the front to rear bias. What have other '02 owners installed and where within the brake lines. I don't want to install an adjustable bias. The car isn't a race car and has a new/full interior.

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that is the way they are supposed to work...;-) you never want the rears to lock first..makes for very scary stopping.

but, you can use different wheel cylinders in the rear to increase rear brake power. which ones are you using now? and are your rear brakes fully adjusted correctly?

and the huge factor is what brake pads are you using up front vs in the rear?

braking technique is also a big factor. if you just mash the brake pedal the fronts will always lock first as the suspension does not have a chance to shift weight forward.

i have the same physical setup and have to use a much more aggressive track pad on the front when on track to offset a slight rear bias.

and...your tires bascially suck. ;-) they do not have enough grip. your better brakes can easily over power their limited capability magnifiying any other issue.

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I have mine with stock disks , calipers and pbr pads in front and 320 drums in back with porterfield shoes and 79 e12 master . This set up

has a nice slight rear bias and if I set the rear drums slightly out I can tune

it out to a more front bias. I like it . 2002s always lock the front so easy into slow tight corners . the rear bias helps to set and rotate the car . I would not recomend it for anyone for street , but I do and like it that way . I am a nut case and like to do auto x and TTs at a big gocart track and it works good.

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Thank you for the information. I'm not sure what front pads are on the car, and yeah I know the tires don't provide adequate grip. I don't recall having the issue with 195/60-14 tires.

Let me know what wheel cylinders would provide a little more braking action. Also, let me have your thought's about rear shoes available, as well as pads up front.

I use spacers to draw the rear drums up - as a wheel would - when adjusting the drums, so I think that they're alright in terms of adjustment.

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The easy way to get more rear bias (I'm not going to get involved in the discussion about if you should or not) is to use the rear wheel cylinder from the 2002 Turbo/2800 CS BMW part number 34 21 1 103 392 It is 22 mm and bolts right up. Try Ireland www.bmw2002.com, www.jaymic.com or www.wallothnesch.com they can be had for about $40-45 each I believe.

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BEFORE YOU DO ANYTHING ~

adjust the rear drum shoes to the slightest 'free dragging'

clearance. re bleed the brakes - be sure no bubbles

are visible from the rear slave cylinders and drive it some more.

By careful adjustment to maximize the rear braking action -

you should be fine as others suggest. The rears should not lock up.

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There are actually at least 3 diameters available-

17, 19, and 22.

I THINK 17 were stock.

19 seemed to be a good upgrade without too much rear

22 will give you too much rear without some sort

of rear pressure reduction for 320 drims

IF you have a relatively aggressive shoe back there.

(Carbotec green and Hawk blue was my 'mix' for this discovery...)

But so much depends on shoe/pad choice it's just not funny.

hah hah

t

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I ran 19 mm rear cyls with the 320mm rear drums with the TII/ventilated calipers and 320i rotors in front and it was still a bit too much front bias. I went to disc rears so never tried the 22mm cyls but if it is too much a adjustable inline bias valve would be the ticket. I put the valve in my car when I put the discs on just in case.

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