Print Page | Close Window

620 Disc Brake Conversion

Printed From: Datsun Mini Truckin
Category: Datsun Trucks
Forum Name: 620's
Forum Discription: The Bullet
URL: http://www.datsunminitruckin.com/forum/forum_posts.asp?TID=2985
Printed Date: 19 Oct 2018 at 8:45pm


Topic: 620 Disc Brake Conversion
Posted By: ZacharyProhodsky
Subject: 620 Disc Brake Conversion
Date Posted: 25 Jun 2018 at 4:24pm
Hey guys

I've been searching around but cannot find an answer or fix to my problem.

I bought the disc brake conversion brackets off ebay, installed everything as every thread I've found pointed me to do. I got to the bleeding portion and no matter how I do it I cannot get resistance in my pedal!
I've done the 3 pumps and hold while releasing the valve. Used a mighty vac, dropped the front of the car down, I have run FOUR big bottles of brake fluid through the system now and still no pressure.
I've re-checked every fitting, Bled the cylinder, the LSV, each brake multiple times in different order and still nothing.
It does get to the point it starts to feel more stuff but then I let it sit for 30 seconds and it goes back to easy push to the floor.
I have also adjusted the brake pedal so it has no play. I took the cylinder off and measured everything to make sure I have the right cylinder for the booster. They are both new by the way. 
Is there something you are supposed to add for the disc brakes to work? Am I supposed to bypass the LSV under the passenger seat?. I am at a loss, my dad is at a loss, our friends are confused.
I beseech thee Datsun group! 



Replies:
Posted By: smooth620
Date Posted: 26 Jun 2018 at 7:45pm
Is the brake mc New? Did you bench bleed it?
If the pedal gets stiff after bleeding but soft after sitting you have a leaking seal in the mc or fluid is leaking into the brake booster.

-------------
Better to learn from other peoples mistakes than to make them yourself.-Anonymous



Posted By: ZacharyProhodsky
Date Posted: 26 Jun 2018 at 8:07pm
MC is new. did not bench bleed as it has bleeders on the MC. bled it from there? 


Posted By: smooth620
Date Posted: 27 Jun 2018 at 4:58am
When I bleed brakes 1 guy pumps 5 times then holds the pedal down while I purge the air out. Pedal pressure will increase after doing each wheel cylinder or caliper. Pedal should be firmer after bleeding. Should be more stiffer with the brake booster after starting the truck. It shouldn't get soft after sitting for a short time.

-------------
Better to learn from other peoples mistakes than to make them yourself.-Anonymous



Posted By: ZacharyProhodsky
Date Posted: 27 Jun 2018 at 11:57am
Yeah that is exactly how I've been doing it and it never gets firmer. I assumed it had something to do with the disc conversion. leaving the LSV.... i dunno at this point


Posted By: smooth620
Date Posted: 27 Jun 2018 at 6:08pm
Try this to isolate the issue.
Diconnect the front brake line from the mc and plug the hole with a brass plug. Bleed the mc and rear brakes. Is the pedal firm? Does it get soft after sitting?

-------------
Better to learn from other peoples mistakes than to make them yourself.-Anonymous



Posted By: silvercreekmotors
Date Posted: 26 Aug 2018 at 3:28pm
Hi, I just installed the same kit this week. I had the same problem and I feel pretty ignorant as to what my problem was. I installed the 300zx calipers backwards. left and right. They fit just fine backwards except the bleeder port is on the bottom of the caliper instead of the top so it wont allow you to bleed the air out. 


Posted By: silvercreekmotors
Date Posted: 26 Aug 2018 at 3:31pm
opps I just realized this is an old post. Hope you got it all fixed.



Print Page | Close Window