dats-injin Posted April 28, 2010 Report Share Posted April 28, 2010 Hello you all, I looked in the search are but could not find any information on my problem. Anyways, my question is I changed my from brakes over to disk, the master is the original from the drums but I am having an issue, when I apply my brakes it doesn't seem to want to release. A friend told me that there is a valve that I need to remove or something. Any of you guys know what I need to do? I was thinking of getting a master from a 280z, but if there's a valve in line I would still need to find it. I followed the hard lines from the master and it runs on the firewall to a copper T-block that splits to right and left brakes. Is there a valve inside the T-block or do I just need the 280z master or better option? Quote Link to comment
dats-injin Posted April 28, 2010 Author Report Share Posted April 28, 2010 Sorry, here are pics of truck, I am new so not sure if the pics will show. I have a photobucket account with the pictures in there. 1 Quote Link to comment
sycloned916 Posted April 28, 2010 Report Share Posted April 28, 2010 Sorry, here are pics of truck, I am new so not sure if the pics will show. I have a photobucket account with the pictures in there. Nice truck those rims look bad ass on it. On the brakes i think most people swap to the 280 master i think and some use the power booster if i remember. Quote Link to comment
motavated Posted April 28, 2010 Report Share Posted April 28, 2010 I was not sure of keeping my truck Mustard. But after seeing your truck. I want to keep it the same! ITS ALLLLLLL RIGHT! For the awesome pics. I present you a thread were a guy had a similar problem. Good luck! :D http://community.ratsun.net/topic/11707-gustavs-1975-low-620/page__p__156042entry156042 Quote Link to comment
motavated Posted April 28, 2010 Report Share Posted April 28, 2010 http://community.ratsun.net/topic/3908-broken-brakes/page__view__findpost__p__51477 Quote Link to comment
kaoss Posted April 28, 2010 Report Share Posted April 28, 2010 God I wish they still made those wheels! Quote Link to comment
SHADY280 Posted April 28, 2010 Report Share Posted April 28, 2010 the problem is that the drum brakes use residual valves to hold pressure against the drum to help reaction time. you can fix that by installing a 78/79 620 master. this will retain the rear drum residual and have no residual on the front. you may need to replace the factory rear bias valve with a manual one to set the balance. this is found under the passanger seat. if you use a 280 master, you wont have the rear residual valve built in, this causes the rear brakes to work a bit slow, also causing increased panic stop distance. Quote Link to comment
SHADY280 Posted April 28, 2010 Report Share Posted April 28, 2010 the problem is that the drum brakes use residual valves to hold pressure against the drum to help reaction time. you can fix that by installing a 78/79 620 master. this will retain the rear drum residual and have no residual on the front. you may need to replace the factory rear bias valve with a manual one to set the balance. this is found under the passanger seat. if you use a 280 master, you wont have the rear residual valve built in, this causes the rear brakes to work a bit slow, also causing increased panic stop distance. Quote Link to comment
dats-injin Posted April 28, 2010 Author Report Share Posted April 28, 2010 Thanks guys for your fast response to my post. I read the post you all hit me up on and totally agree with adjusting the push rod. I had forgotten all about that when I did the disc conversion because it worked great for a week until today when it really started getting noticeable tighter. Come to think about it, I installed some new pedal plates and had to drill through the old plates to mount the new ones and do remember having to really push down to drill. I am sure that helped in creating the added pressure that I am experiencing. Yeah, the mustard color isn't the most likeable color out there but in my case it makes the truck pretty unique and original paint is always better, hehe. Thanks, I will get back with results tomorrow after I adjust push rod. I am 100% sure that is the problem because I remember that happened before on friends honda afte new booster/master install. Quote Link to comment
herculesinwyoming Posted April 28, 2010 Report Share Posted April 28, 2010 great looking truck, the door dings must piss you off, i have them in all 4 of my vehicles. people just dont care Quote Link to comment
dats-injin Posted April 28, 2010 Author Report Share Posted April 28, 2010 Tell me about it, I am not liking them holes. They were from the previous owner using them triable bar with those huge rear merrors. I want to fix them but then that would mean repainting the whole truck and I want to keep the original paint. O well, it just adds to the originality of the truck, hehehe.... Quote Link to comment
slowdown Posted April 28, 2010 Report Share Posted April 28, 2010 heck ya keep it original!!! what color was the truck that always had to take a crap... musturd Quote Link to comment
Jersey Posted April 28, 2010 Report Share Posted April 28, 2010 nice looking truck...love the color and the wheels! Quote Link to comment
nis720 Posted April 28, 2010 Report Share Posted April 28, 2010 God I wish they still made those wheels! I always wanted Timeless 6 wheels too. Quote Link to comment
motavated Posted April 28, 2010 Report Share Posted April 28, 2010 I always wanted Timeless 6 wheels too. They were on cragslist for a while. Maybe a week? They came of a white 620 I believe with a crazy paint job. I think that truck is in ratsun as well.... Quote Link to comment
nis720 Posted April 28, 2010 Report Share Posted April 28, 2010 They were on cragslist for a while. Maybe a week? They came of a white 620 I believe with a crazy paint job. I think that truck is in ratsun as well.... This truck was at the SWDP BBQ last year. Quote Link to comment
kaoss Posted April 28, 2010 Report Share Posted April 28, 2010 I'd love to have them if you ever want to sale them. What size are they? Quote Link to comment
budsaipan Posted April 28, 2010 Report Share Posted April 28, 2010 Where did you get the front valance? Quote Link to comment
dats-injin Posted April 29, 2010 Author Report Share Posted April 29, 2010 Sorry, the wheels aren't going to be for sale. I've had the wheels on the truck for a long time now, if ever, they will go with the truck, hehe. The rims are 8x18, I have 215/35/r18 on them, I wanted the stretch look and was also concern about rubbing the fenders. These rims aren't from that truck unless he sold them to me about a yr ago. I have been slowly working on my truck for a while now, been reading here but never register as a member until I ran into this brake problem and couldn't find the anwser. Most of the other stuff was just cosmetic which I can handle. The valence I made from a peice of sheet metal I had laying around. It didn't cost me much but time, skin, elbow grease, and sum blood. I did split the master from the booster and turn the push rod all the way in on the threads, essentially making it shorter. I hope that's the right direction but I haven't had a chance to drive it enough to see if its made a difference. I drove it around the block and the only noticeable difference is I have to step deeper before I could feel the brakes working. I played around with the clip that bolts behind the pedal to the rod that goes through the booster but only difference I could see there is that it just moves my pedal down or up, so I just left it alone. I will drive it to work tomorrow and hope it doesn't lock up on me. I really didn't notice any changes. Quote Link to comment
mklotz70 Posted April 29, 2010 Report Share Posted April 29, 2010 I could be wrong, but my understanding is that the residual valve is built into the bottom of the m/c, right where the line connects. That really big nut is holding it in. If you use a m/c of a disc/drum 620 or 280z, it should work fine, but I'd put an adjustable proportioning valve in the rear circuit. The biggest difference between the 620/280 m/c's are the bore....280 has a 15/16" bore...your pedal will be firmer and not travel as far. Quote Link to comment
dats-injin Posted April 29, 2010 Author Report Share Posted April 29, 2010 Thanks for that bit of info, I was looking for someone to tell me where that valve was located. What I did probably isn't going to change my condition. Looks like I am going to have to get me a 280z master and proportioning valve. Will the booster from the 280 bolt up? What booster should I get? Quote Link to comment
dats-injin Posted May 8, 2010 Author Report Share Posted May 8, 2010 Well, just wanted to close this post. I went with a new 79 booster and master. I had to grind the spacer between the booster and master in order to make it work. Did some adjustments of the push rod and everything is looking good. I got good brakes, yeeeehaaa!!!! Quote Link to comment
SHADY280 Posted May 8, 2010 Report Share Posted May 8, 2010 yes the valve is in the master where the big nuts are. thats why you cant use a 280zx master for rear drums. you may still need the bias valve. go find a gravel parking lot, take a friend. the rear should lock just before the front, like 1/4 second before. if not adjust the bias with said valve. Quote Link to comment
Grey_Matter Posted June 3, 2010 Report Share Posted June 3, 2010 how did you swap the 73 to front discs? i cant find a write up anywhere. i did read the 620's with discs front suspension parts arent interchangeable Quote Link to comment
Grey_Matter Posted June 3, 2010 Report Share Posted June 3, 2010 N/M i found my answer http://community.ratsun.net/topic/10169-73-620-disc-brake-swap/page__hl__disc+brake+conversion__st__20 Quote Link to comment
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