[bowtieboy67]

Just finished up a swap on my 67 Beaumont with a mbm power brake kit.

Bench bled the heck out of the master cylinder, brakes, etc, tested the prop valve that came with the kit to check that its centered.

Now for my problem, you can visually see the calipers/pistons move on the front brakes. But as soon as you drive the car it seems all the brake pressure is being applied to the rear. It has a nice firm pedal as well.

Ive done a whole lot of googling and havent really come up with any problems that relate to mine.

Would a adjustable rear prop valve help my problem if installed after the current one?

Or would it be possible to run the front brakes straight off the mc and put an adjustable on the rear? If I were to do this would I be able to just plum the front lines off the mc as it has dual outlets?


Any input appreciated.

 

[NickeyChevelle]

First: reread the instructions, make sure you followed every instruction, completed every step. Second: call the manufacturer and ask them for help -- they won't stand behind it (liability-wise) if you mess with it.

 

[bowtieboy67]

We went over everything multiple times.

 

[bowtieboy67]

We went over everything multiple times. Still to no avail.

Ill most likely call mbm wed.

 

[novaderrik]

do you have the front brakes hooked up to the line at the master cylinder that goes to the biggest reservoir?

 

[bowtieboy67]

Yup

Hooked er all up the way the kit came which is the big bowl on the front.

 

[Andy's Auto Repair]

Are the bleeders on top of the calipers when mounted?

 

[driveshaft-texas]

It takes a few hurdred miles for frictions to mate to the rotors . Have you driven it enough to do this? If not, make a number of light -medium speed stops-don't make a lot of heat in the pads ,and see if it helps.

 

[novaderrik]

It takes a few hurdred miles for frictions to mate to the rotors . Have you driven it enough to do this? If not, make a number of light -medium speed stops-don't make a lot of heat in the pads ,and see if it helps.

i've done hundreds of brake jobs, and new pads and rotors- even the cheap stuff- will always stop the car pretty well even before being properly "bedded" in.

the pads will sometimes glaze over initially- a quick hit with some 80 grit on an orbital sander will take car of that..

 

[driveshaft-texas]

i've done hundreds of brake jobs, and new pads and rotors- even the cheap stuff- will always stop the car pretty well even before being properly "bedded" in.

the pads will sometimes glaze over initially- a quick hit with some 80 grit on an orbital sander will take car of that..

We don't know what he is expecting from all these new parts....he stated caliper piston is moving so SOME pressure is being applied,and petal is firm, and if the pad is a better quality(read "harder"), it make take some time to have good stopping power. A cheap soft pad might be a good experiment to see if it helps. Possible to have a bad PV but not likely...although in todays parts world and where(?) everything is built, chances are moreso

 

[bowtieboy67]

Got everything figured out, after a whole lot of reading I found out the following.

The m/c my kit came with was a 1" that could be used for manual brakes/power brakes

http://mbmbrakeboosters.com/index.php?page=shop.product_details&flypage=mbmflypage.tpl&product_id=159&category_id=10&option=com_virtuemart&Itemid=6

Read that most gm power brake vehicles had 1 1/8" bore m/c's. So i searched around my buddies junkyard and found that 70's GM trucks had exactly that. So I picked up a new one. Bench bled the crap out of it, fired that on, bled the brakes.

I now have a firmer pedal(how it should be i think) with good brakes, they seem to work pretty well. After 70 miles of driving the brakes seem to be getting better.

Thanks again.

 

[novaderrik]

i assume you called up MBM to tell them that their conversion kits are poorly engineered and dangerous to the general public, right?

 

[-SS454-]

the 1 inch bore should have given you more brake pressure, but a longer pedal. Were the brakes locking up before?

 

[bowtieboy67]

the 1 inch bore should have given you more brake pressure, but a longer pedal. Were the brakes locking up before?

Yeah guess I just used different terms to describe the situation. Only back brakes were. You could see the front calipers moving/stop wheels from rotating.

They just werent getting enough fluid. I believe if I put the manual set up back on the 1" would have worked just fine.

Pedal stroke is quite a bit shorter now as well.