rear drums to discs

[e30-320i]

i have the chance of a cheap 325i (rear accident damage)and am thinking of swapping my lump for the 325i but i have drum brakes at the rear so i would need to change them too how much work is involved in converting i guess i would have to change the fronts too both cars are facelift models

[DanThe]

Easiest way is to swap the whole rear beam over with everything intact, while its off you can get some new bushes in aswell!!

[Treeman612]

Have done the swap on my 320i - I agree with the idea of taking the whole axle/diff/susp.arm off the 325 donor and putting on to your car - also recommend braided steel hoses at the same time, as well as new axle bushes.

[jb81]

or you can just swop the swing arms, if all the wheel bearings,discs and pads are ok and your beam bushs are ok just bay new hand brake cables and 2 new steel brake pipes, remove hand brake cables and brake pipes, undo the shock bottom bolts and the 2 bolts holding each swing arm to the beam, then just build back up with new parts and bleed brakes, its not a bad job to do just take your time and think how it all fits together and give your shelf the full weekend for fuck ups, the front brakes are the same hop that helps

[Templ8e30]

Have a look at the tech article here http://www.e30zone.co.uk/modules.php?na ... htrail.htm

Cheers,

Iain T

[stuartgallafant]

you also have to take into account brake biasing...

discs have far greater brake efficiency compard to drums, therefore, if you send the same hydraulic pressure down the line thats intended for a drum, the discs will lock and the car will swap ends

i believe that using the master cylinder from the donor car will overcome this problem, but im not 100% sure...

safety first remember mate....

[6inline]

As said above - complete swing arms + handbrake cables. Do the bearings if you can while you are on. I didn't and have to do them now .
Another thing I've noticed - my 320i didn't have rear sway bar, so took it from the donor too. It makes a difference even before putting my rear top strut brace.

[Templ8e30]

you also have to take into account brake biasing...

discs have far greater brake efficiency compard to drums, therefore, if you send the same hydraulic pressure down the line thats intended for a drum, the discs will lock and the car will swap ends.

That's what I thought, the master cylinders are the same so I thought that I'd have to use a different pressure regulator but they are the same part numbers too.

I ended up leaving the hydraulics alone and have never had any trouble in the 18 months since I converted to discs. The front brakes always lock well before the rears even in the snow or when wet and greasy.

It might have something to do with the fact that the drums are large in diameter with quite a wide friction area ( looki at the tiny drums on golfs etc) as opposed to the disc which has quite a small friction are on the e30.

Anyway, The discs perform brilliantly without any hydraulic mods.

Cheers,

Iain T

[e30-320i]

thanks alot for all your advice guys. it doesnt seem such a difficult job as i was expecting i'm just weighing up how much work is involved in the conversion as i may just break the car and put the cash towards a 325i

[DanThe]

you also have to take into account brake biasing...

discs have far greater brake efficiency compard to drums, therefore, if you send the same hydraulic pressure down the line thats intended for a drum, the discs will lock and the car will swap ends

i believe that using the master cylinder from the donor car will overcome this problem, but im not 100% sure...

safety first remember mate....

A correctly working drum brake takes far less pressure/effort to operate than a disc brake, will slow you down quicker and is far more likely to lock than a drum

[6inline]

thanks alot for all your advice guys. it doesnt seem such a difficult job as i was expecting i'm just weighing up how much work is involved in the conversion as i may just break the car and put the cash towards a 325i

Probably the easiest and by far the best upgrade idea