Register    Login    Forum    Search    FAQ



Board index » TECHNICAL » Wheels/Tires/Brakes Technical




Post new topic Reply to topic  [ 4 posts ] 
Author Message
 Post subject: Front Brakes Locking Up
 Post Posted: Tue Nov 28, 2017 5:57 pm 
Offline
Dragway Regular

Joined: Fri Jul 16, 2004 10:13 pm
Posts: 711
Location: Central Jersey
Seems like the proportioning valve is too much bias toward the front. The frt brakes are locking up much too easily.

Has anyone out there have a similar problem and could verify that it's the proportioning valve?

Thanks


Top 
 Profile  
 
 Post Posted: Thu Nov 30, 2017 5:23 pm 
Offline
Amateur Racer

Joined: Tue Jun 08, 2004 1:06 pm
Posts: 226
Location: Houston, TX
Most likely not the prop valve, but if the low pressure switch was triggered, you could have just the front brakes working and not the rear. This may be your issue.

I don't know your tire or brake setup, but if you have skinnier and/or shorter tires on the front than the back, your front brakes will lock up easier as you have less contact with the road with a skinnier and/or shorter tire than a wider and/or taller tire.

A smaller bore master cylinder would create more line pressure. Stock size is 24mm bore diameter. A smaller 7/8" bore size was also available and came equipped on early manual brake cars. You put a manual brake master cylinder on a vacuum boosted car, you will have super sensitive brakes. Same effect will happen with upsizing to a larger booster or upgrading a booster from single to dual diaphragm.

Also, going with a caliper with a larger piston area over stock will also make your brake more sensitive as the clamping forces will increase with more piston area. Going from a stock single piston, to a dual piston Blazer setup will make your brakes more sensitive as the piston area went up.

Pads could also be a factor as the front pads could be more aggressive than the rears causing the brakes to lock up easier.

Bottom line it could be multiple things.

What is your brake setup front and rear?
What pads are you using?
What has been changed out in your brake system?

_________________
David Schultz
MalibuDave
www.manualbrakes.com
https://www.facebook.com/manualbrakescom-576443512373024/


Top 
 Profile  
 
 Post Posted: Sat Dec 02, 2017 12:02 am 
Offline
Dragway Regular

Joined: Fri Jul 16, 2004 10:13 pm
Posts: 711
Location: Central Jersey
Thanks for responding.

235-60X15's all around, semimetallic pads, the rear wheel cylinders were changed to those used on S-10s with manual brakes., the frt calipers are stock. The rear brakes are working as when the drums were pulled there was brake dust. Going to check to see what's the rear line pressure at. Suppose it would be good ito know what the pressure is supposed to be?

The master cly is still original after 230k+miles. Could it be internally leaking?


Top 
 Profile  
 
 Post Posted: Sat Dec 09, 2017 9:31 am 
Offline
Amateur Racer

Joined: Tue Jun 08, 2004 1:06 pm
Posts: 226
Location: Houston, TX
Sorry for the late reply.

I could be the master cylinder. 230K is a lot of miles.

I am not sure what the rear line pressure should be, but with 7/8" bore S10 wheel cylinders, your rear drum brakes should be more sensitive than the front. It makes me think there is air in the line or your shoes are not adjusted out enough, but since the master cylinder has 230K miles, I wouldn't rule the master cylinder out either.

If you do replace the master cylinder, I would go with a newer master. There is a right hand drive S10 master cylinder that should bolt right up. Check the link at the top of the Brake Forum on maliburacing.com

http://www.maliburacing.com/forum/viewt ... 5&t=124945

If I needed to replace my master cylinder, I would go with the S10 master cylinder from the link above.

_________________
David Schultz
MalibuDave
www.manualbrakes.com
https://www.facebook.com/manualbrakescom-576443512373024/


Top 
 Profile  
 
Display posts from previous:  Sort by  
 
Post new topic Reply to topic  [ 4 posts ] 

Board index » TECHNICAL » Wheels/Tires/Brakes Technical


Who is online

Users browsing this forum: Yahoo [Bot] and 2 guests

 
 

 
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to: