Brake page

 

Rear disc conversion

So ya want rear disk brakes. Well so do I! This is the setup I'm working on but have not tested yet and the crap I'm going through to get it right.

It all sounded so easy when I saw the parts list on the net:

2 brackets form A&A manufacturing (my source did not have part #s so I guessed, bad guess but I have better input for you :-) )

2 rotors from the front of a '90 Chevy K1500 truck

2 loaded front calipers from a '80 Monte Carlo

2 brake hoses Raybestos #38149 (theese list for an '81 Nissan 200sx but my supplier had to cross to a Beck Arnley part and I ended up with something that doesn't work, this issue is still up in the air) Update I just got the hoses for the '80 Monte front calipers Federated# 10-36847 (Bendix# 77227, Wagner# 106886) I will be making custom lines with my new double flare tool, SAE on one end and metric on the other.

 

OK, the fun begins:

 My first screw-up, bought the wrong brackets, no biggie I got tools. None of the brackets A&A has for the 3" tube will work as a direct weld-on deal. One flat bracket that bolts to the back side of the axle tube flange won't work either. You run into offset issues. One possibility would be to have the axle flanges cut down to fit inside Taco front rotors witch have more offset. At this point I got some 1/4x1" strap and "refabbed" what I had. The base of the bracket is welded (and bolted) to the backside of the tube flange. Then the ears that the calipers bolt to are welded to to the outside face of the bracket base.

If you go for the Taco rotor setup I would say go with the AA-113-A brackets and weld to the tube as needed. With the Chevy rotors I would get the #AA-056-A for the base and #AA-113-B to weld to it for the caliper.

The Chevy rotors must have the center hole machined to fit over the axle center.

Now comes brake lines. Like I said earlier the ones I have are poopoo and I'm stuck until Monday. Update Bought a double flare tool and a 60" x 3/16 steel brake line. I will be making custom lines with SAE on one end and metric on the other.

 

My wheel bearing tool:

Master Cylinder upgrade

It seems putting all these Chevy brakes has caused another problem, My little Toy master cyl doesn't push enough fluid and boost sucks.

The odd details:

The upgrade is a Chevy 3/4t master adapted to a Tundra booster.

In my case I'm using an adjustable proportioning valve for the rear from Wildwood. It only has 2 ports instead of 3 like the stock one so a little re-arranging has to be done. The stock "load sensing valve" has a third port tapped into the left front brake, this has to be eliminated. The left front line before the tee has enough extra line to be re-routed straight to the hose fitting. (this is temporary until the new front axle goes in)  I then ran one new line from the master to the new adjustable valve.

Old on the left new on the right. My drawing doesn't show it but the red line going to the tee on the frame rail has plenty of length to go in place of the pink line to eliminate the tee with the green rear line. (with careful bending)

The lines, oh the lines. Adapting a SAE threaded master into a metric vehicle is just too damn fun! Ok, it's not...... Adapting SAE lines to a metric master is easy but going the other way is a bit trickier. This takes deep thought............................ 

OK, the deal is:  it's easiest to replace the metric steel lines coming out of the master with SAE steel lines and use adapters to connect them to the metric fittings. You will also need a couple adapters at the master ends for thread size.

Parts:

Adapter- takes SAE standard 3/16 tube fitting (3/8-16 thread) and fits into m-cyl port with 1/2-20 thread for 3/16 tube Motomite #43390 from pep boys.

Adapter- takes SAE standard 3/16 tube fitting (3/8-16 thread) and fits into m-cyl port with 9/16-18 thread for 3/16 tube Edelman #258302 Everco #7830 Weatherhead #7911

Adapters(2)- takes SAE standard 3/16 tube fitting (3/8-16 thread) and fits into Toy style 10mm x 1.0 metric threaded fittings Edelman #270300 Everco #3025B Weatherhead #1443

Master cyl for 74 Chevy 4wd 3/4 ton pickup w/front disc.

Tundra power brake booster

Handful of 3\16 brake lines and adapters

Well one more little snag, the chevy master cylinder/tundra booster combo is not as easy as it first looked. The tundra master cylinder has a "snout" that sticks out into the booster, without the snout on the chevy master there is a big vacuum leak. So here's my answer:

Before

The poker

After

Many requests have been made for dimensions, here ya go:

These dimensions are for the Tacoma adjuster/plunger tip installed on the Tundra booster. One was longer than the other so this will change the hole depth if you don't swap that over. With it in place, the plunger should be 1/4" recessed from the face of the booster for a basic adjustment. 

Essentially you want this to be as close to the master cyl piston as possible without pushing it in. In other words, the least amount of clearance that allows the master cyl piston to fully return. This is critical for maximum performance. If the master piston cannot fully return, ports can be blocked not allowing brakes to release properly.

 

 

The other (maybe better) option:

While the jury is still out on my setup, here's a setup using a stock booster:

The Taco has a 75mm x 45mm bolt pattern. This plate is made from 1/2" steel or you can purchase one from Allpro offroad.

 

 

Misc. Part#'s:

Raybestos# BH23057 brake hose: takes SAE 3/16 steel brake lines w/inverted flare on each end and is made to fit into a frame tab with a 5/8" hole and is approx. 12" long.

good brake upgrade info

Stant brake line adapter listing

Stant inverted flare tube fittings

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