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Brake Booster


jchristians

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Who here has a brake booster on their 521 and which one did you use?...620 booster? Any Wilwood recommendations? Got my front discs installed...but, still not stopping how I'd like it to! Thanks!

 

I have a power brake booster on my 69 datsun 521 diesel kingcab truck, but I can't remember anymore what it came from, I thought it was from a early ford courier, but went out and looked at that booster, wasn't that one. I also used a 79 620 brake M/C, when I do it again, which I will, I am going to try the ford courier booster with the ford M/C it came with, as it was made for front disc/rear drum brakes with approximately the same weight vehicle. Here is my thread with photos of the booster, it might even say what booster it was in there, and how I put it in there.

http://community.ratsun.net/topic/22928-1969-datsun-kingcab-project/page__view__findpost__p__375219__hl__wayno__fromsearch__1

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There is limited space for the booster to fit above the steering column and beside the clutch master. The 620 is very similar to the 521 in this regard and a 620 booster shoud fit. You will need the 620 pedistal between the booster and the firewall to spaceit outward for the proper clearance.

 

Did the 521 have dual masters? Maybe it was my '68 dime I converted.

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Here is what I did, I used a 720 pedestal and modified it, I didn't know the 620 pedestal would fit in a 521, I thought the two masters were farther apart in the 620, I am going to have to look into this.

DSCN1144.jpg

DSCN1143.jpg

DSCN1145.jpg

As you can see, the clutch master sits on the 720 pedestal also, helps keep the brake pedestal in position, as the bolts holding the brake master side had to be repositioned. Originally I used the 521 brake master(single reservoir), but I had to remove the internal residual valve, as it was made for drum brakes all around, and was causing the front disc brakes to seize up, it also had suction issues, when the brake master is bolted to the firewall, it has a rubber cap to keep the dust out of the internals, when you bolt it up to a booster, you have to take the rubber dust cap off, it then makes a seal that it normally doesn't have, so when you try to bleed the brakes, it pulls air threw the seal from the booster around the shaft when you step on the brakes, but when you let off the pedal, instead of the air going back into the booster cavity, it builds up enough pressure to push the air threw the M/C seal, introducing air into the brake system, what a pain that was to figure out, I found if I drilled a small hole in the groove where the dust cap mounted on the master, no more problem, as the pressure created exited out of the small hole.

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  • 2 weeks later...

Wayno, I just realized that I just built a setup very much like yours here, but used a series 1 240Z booster that I had(paid $400 for it years ago and never used it).

What size is the master cylinder you used? Mine is a 7/8" but I might need bigger for the huge Chrysler calipers on my front axle.

 

 

2011-11-10%25252011.19.51.jpg

 

 

Still have to mount it to the 521 firewall

 

I'm thinking about using a standard clutch master cylinder such as a Maxima/ Z car one since they are much easier to find parts for.

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Wayno, I just realized that I just built a setup very much like yours here, but used a series 1 240Z booster that I had(paid $400 for it years ago and never used it).

What size is the master cylinder you used? Mine is a 7/8" but I might need bigger for the huge Chrysler calipers on my front axle.

 

 

2011-11-10%25252011.19.51.jpg

 

 

Still have to mount it to the 521 firewall

 

I'm thinking about using a standard clutch master cylinder such as a Maxima/ Z car one since they are much easier to find parts for.

 

Mine is a 13/16 bore, it's for a 1979 datsun 620, as they are the type of brakes I have on my KC 521 at this time, the 620 and early 720 have the same brake package, but as time goes by, I will change over to the 85-86 vented rotor/caliper type, as I have that vented type on my 521 work truck now, and I now beleave it seems a little better in the braking department. As you can see in the photos, I did not relocate the clutch master, I just flipped the pedestal upside down, and bored the hole in the proper place for the clutch master, and mounted it onto the pedestal also, this helped to solidly mount the pedestal so I didn't need any side pressure braces for the booster connected to the inner fender, I hope this makes sense to you. If you look close, you can see I also relocated the mount bolts to above and below the centerline of the brake master, as i was having steering column interfearance issues also, but it works great.

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