Front BMW brakes locking front wheels all the time, why...please guys can i have your advice? Options

[budman5201]

I recently bought new rear calipers, redid the front BMW brakes up front and installed HAWK race pads up front. The braking has significantly improved! YES! but now i have one dilema......The front brakes lock up EASILY and the rears never at all..........I wish i could make all them lock up in emergency situations or at least more Braking in the rear.


Did i just significantly make the front brakes better by installing new race pads and BMW brakes? Can i adjust anything with the stock rear system to get more pressure to the back so i dont lock up the front VERY EASILY???

thanks guys i appreciate your help.....

Stock 1.7 liter GOING SUBARU 2.5 200 hp N/A soon!! Trying to make everything else PERFECT before i get my third Subaru done.....The braking was lacking on my last conversion......

thanks!

[Eric_Shea]

QUOTE(Brett W @ Nov 14 2008, 06:22 AM)

Toss the stock rear calipers and put the stock front calipers on the rear. Then add the T. That setup worked really well with PBR metal master pads all the way around. The fronts would lock up nicely and the rears would lock up shortly after that. Very controllable and predictable. What master are you running?



But then you have no hand brake, which is not only illegal, but many would call it dumb. The Cap'n

Couple things in there I would call dumb... especially for a Starbucks car. Sorry Brett.

* Fronts in the back - now you have a 43mm piston where a 33 used to be. Porsche didn't do this until 1984 with the 3.2 Carerra and they installed a P-valve in the 911 for the first time to compensate for this. 911 track guys have complained of squirrely handling when attempting to remove this as well. This is a narrow bodied, solid rotor street car.

* T Fitting - As explained. Saftey feature that prevents the rears from locking. Your statement that the "rears would lock up shortly after that" should scare the living hell out of anyone reading it. If the rears lock in any angle off dead center in a 914 you risk spinning like a top in a mid-engine car.

* Metal Masters - Those are the worst pads I know of. No noise, no dust, no stop.

Since many have made this "upgrade" (cause I guess Pelican isn't about to take that stupid article down anytime soon), I'll offer my recommendations of what I would do if I inherited this misbalanced setup:

1. Start looking for a nice 911T front strut solution and start saving lots of money for a proper rear solution.

**now that I got that outta the way** (IMG:style_emoticons/default/smile.gif)
2. Ensure that my rear calipers are working properly. Not just the venting clearance, make sure they're operating as many have stuck pistons etc.
3. Get the same pads all around.
4. Make sure the venting clearance is set to .004" not .008"
5. Get a 19mm Master Cylinder. Don't get the Chinese copies just yet because I hear there are problems still.
6. Get a cooling kit from AJ Racing/Alan Johnson Porsche. Very simple and very effective.
7. Finally - if you determine that your rear shut-off valve is coming on too early and shutting down your rears I would then attempt to adjust it.

In Budman's situation I doubt that's the case. I think he'll be in a different place once he gets the proper pads on the back and has them vented and bedded in.

I like the thread because it spells out a LOT of things:

1. BMW Calipers have 40% more pad area and will heat up your solid rotors and cause a mis-bias in the rear. This is not as crucial as it seems in this thread because Budman has good pads up front and old glazed bad pads in the back. Which leads me to my next reason I like this thread... (IMG:style_emoticons/default/biggrin.gif)

2. If you "really" want to upgrade your 914 brakes, GET REALLY AWESOME PADS... like our Buddy Budman did. This really goes to show how an awesome pad will make your car stand on it's nose. If you think $100 is too much to pay for pads, especially when you have $25.00 pads waved under your nose all day; think again.

Again gang, our 914's can lock up their brakes again and again and again with little or no fade. That being the case, you don't have a caliper problem. If you're not getting the braking performance you think you should be getting, check your pads and your tires.

[Solo914]

QUOTE(Brett W @ Nov 14 2008, 06:22 AM)

Toss the stock rear calipers and put the stock front calipers on the rear. Then add the T. That setup worked really well with PBR metal master pads all the way around. The fronts would lock up nicely and the rears would lock up shortly after that. Very controllable and predictable. What master are you running?



But then you have no hand brake, which is not only illegal, but many would call it dumb. The Cap'n

Couple things in there I would call dumb... especially for a Starbucks car. Sorry Brett.

* Fronts in the back - now you have a 43mm piston where a 33 used to be. Porsche didn't do this until 1984 with the 3.2 Carerra and they installed a P-valve in the 911 for the first time to compensate for this. 911 track guys have complained of squirrely handling when attempting to remove this as well. This is a narrow bodied, solid rotor street car.

* T Fitting - As explained. Saftey feature that prevents the rears from locking. Your statement that the "rears would lock up shortly after that" should scare the living hell out of anyone reading it. If the rears lock in any angle off dead center in a 914 you risk spinning like a top in a mid-engine car.

* Metal Masters - Those are the worst pads I know of. No noise, no dust, no stop.

Since many have made this "upgrade" (cause I guess Pelican isn't about to take that stupid article down anytime soon), I'll offer my recommendations of what I would do if I inherited this misbalanced setup:

1. Start looking for a nice 911T front strut solution and start saving lots of money for a proper rear solution.

**now that I got that outta the way** (IMG:style_emoticons/default/smile.gif)
2. Ensure that my rear calipers are working properly. Not just the venting clearance, make sure they're operating as many have stuck pistons etc.
3. Get the same pads all around.
4. Make sure the venting clearance is set to .004" not .008"
5. Get a 19mm Master Cylinder. Don't get the Chinese copies just yet because I hear there are problems still.
6. Get a cooling kit from AJ Racing/Alan Johnson Porsche. Very simple and very effective.
7. Finally - if you determine that your rear shut-off valve is coming on too early and shutting down your rears I would then attempt to adjust it.

In Budman's situation I doubt that's the case. I think he'll be in a different place once he gets the proper pads on the back and has them vented and bedded in.

I like the thread because it spells out a LOT of things:

1. BMW Calipers have 40% more pad area and will heat up your solid rotors and cause a mis-bias in the rear. This is not as crucial as it seems in this thread because Budman has good pads up front and old glazed bad pads in the back. Which leads me to my next reason I like this thread... (IMG:style_emoticons/default/biggrin.gif)

2. If you "really" want to upgrade your 914 brakes, GET REALLY AWESOME PADS... like our Buddy Budman did. This really goes to show how an awesome pad will make your car stand on it's nose. If you think $100 is too much to pay for pads, especially when you have $25.00 pads waved under your nose all day; think again.

Again gang, our 914's can lock up their brakes again and again and again with little or no fade. That being the case, you don't have a caliper problem. If you're not getting the braking performance you think you should be getting, check your pads and your tires.

Eric,
Since we are on the topic, and you have recommended the exact solution I have but I am still having problems maybe you can help.

I have rebuilt front calipers from you, rears that I have tested and seem to be in good working condition(adjusted), a new 19mm Master Cylinder, SS brake lines and Portfield R4S pads and I still can't lock em up. I have autocrossed and roadraced(specmiata) so I am familiar with brakes and typical bedding procedures but I have tried almost everything, checking for pad glaze, readjusting the rears, standard rebleed then tried bleeding with a vacuum bleeder etc. Could it be the proportioning valve? Could I not have bench bleed the new master cylinder well enough? I have the whole brake system apart right now(5lug swap, redrilled rotors and hubs) so I would like to get this taken care of. Any thoughts.

Kyle