Manual Brake Conversion on a 1980 El Camino

[pontiacgp]

we used a chrysler manual master for our circle track car and used the stock 2nd gen camaro calipers in front with stock wheel cylinders in back...rules limit what upgrades we can do. The brakes work great. If you have trouble with the pads backing off you can install a 3 lbs residual valve in the front brake line...the drum brakes use a 10 lbs residual valve located in the proportioning valve.

 

[nawlins-tim]

keep 'em comming!!! One question though. Is there any way to tell( from the outside) What type of Master Cylinder you have? Step bore or straight? And the bore size? Did you disassemble the master to look at the internals? Keep us posted. Good "sticky" when you get done!!

 

[malibudave]

keep 'em comming!!! One question though. Is there any way to tell( from the outside) What type of Master Cylinder you have? Step bore or straight? And the bore size? Did you disassemble the master to look at the internals? Keep us posted. Good "sticky" when you get done!!

GM step bore master cylinders came in cars and trucks starting in the 1981 models. I don't know exactly when they stopped useing them, but I suspect sometimes in the 1990s.

They step bore master cylinders that came on rear drive cars and trucks look like this one from an S-10:

If you look at the base of the master cylinder where it bolts to the fire wall, there is an increase in diameter of the cylinder. The bore in that area is larger than the bore toward the front of the master cylinder. If you look at the reservior, you can see that it also steps up.

If you compare it to a strait bore master cylinder below, you can see the differences. Smaller diameter at the base with a flat bottom reservior.

 

[malibudave]

UPDATE:

I had trouble getting the brakes bled. I bench bled the system, but for some reason I couldn't get any pedal after I installed the system. I am going to use a bleeder kit to push brake fluid up to the master cylinder from the wheel cylinders and calipers. I will not be able to get to it until January 21st or 22nd, so stay tuned in until then.

Let me know if you have any questions.

 

[malibudave]

I want to let everyone know that there has been one issue with the calipers that I recommended from Speedway Motors. Its the Speedway Motors Big Bore Metric Calipers - PN# 91031040 $59.99 for each.

Here are the links that describe the issue.

http://www.maliburacing.com/forum/viewt ... 2&t=111382

viewtopic.php?f=14&t=35367

I have not had any problems with the ones I have bought. I have been told that these calipers are made by U.S. Brake when I first bought mine from Speedway Motors.

There are other options for big bore calipers, but they are a little more expensive from Wilwood.

http://www.speedwaymotors.com/Wilwood-G ... 24192.html

 

[malibudave]

Here is a link to a person that carries new Proportioning Valves for Ford, GM, and Jeep.

http://proportionvalves.com/

Here is a link to a disc/drum PV for a g-body from the http://proportionvalves.com/ site.

http://www.carolinaclassictrucks.com/78 ... u-PV2.html

Here is a link to a disc/disc PV for a 2nd gen f-body that looks like it will work with g-body brake lines if you convert to rear disc brakes. Please call to confirm it will bolt in.

http://www.carolinaclassictrucks.com/79 ... M-PV4.html

MOPAR MASTER CYLINDER RETROFIT
I may have found a way to retrofit a 7/8” mopar (1993 Dodge Shadow) master to a g-body for manual brakes. I have not tested this yet to see if this works.

For the Front Brake port on the Proportion Valve:
Edelmann 258350 - Adapter-Standard To Dual Master Cylinder - 3/16" Tube - 3/8-24 Female Inverted Flare Seat x 1/2-20 Male Inverted Flare

For the Rear Brake Port on the Proportion Valve:
Edelmann 258340 - Adapter-Standard To Dual Master Cylinder - 3/16" Tube - 3/8-24 Female Inverted Flare Seat x 7/16-24 Male Inverted Flare

I don’t know the length of the brake lines from the proportion valve to the mopar master, but flared lines are less than $10 each from the auto parts stores. It should be about 2 to 3 foot of line. A coat hanger can be used to find the actual length needed.

If this setup works, this will be the cheapest way to get an aluminum master cylinder retrofitted to a g-body.

Let me know if you see any issues with what has been posted above.

 

[malibudave]

A Wilwood master cylinder will not work with the angle of a g-body firewall if the Wilwood master cylinder is bolted directly to the firewall. It physically bolts up, but there is a hole at the bottom of the master cylinder that regulates the fluid from one reservior to the other. When bolted directly to the firewall, the angle will let all the fluid run to the back reservior and the front reservior is left almost empty.

The Wilwood master should work on a TRZ or TNT adapter plates because these adapter plates correct the angle of the firewall and allows the master cylinder to sit horizontal (level) to the ground.

 

[malibudave]

I have purchased 3 different metric calipers for comparison:

**CCP big bore 2.75" bore (2.565" piston diameter) metric cast iron caliper – WEIGHT 6 lbs 11.2 oz bare with slider bushings installed
**US Brake standard bore 2.5" bore (2.376" piston diamter) metric cast iron caliper- WEIGHT 6 lbs 4.7 oz bare with slider busings installed
**Wilwood small bore 2.0" bore (1.981" piston diameter) metric cast iron caliper - WEIGHT 4 lbs 1.7 oz bare with NO SLIDER BUSHINGS INSTALLED.

A while back I purchased NEW the $59.95 each, big bore calipers from speedwaymotors.com. There was some manufacturing issues or problems with these calipers and they sent me replacement calipers. The replacement calipers are NEW CCP big bore metric calipers. PN CP412526. Online, these are the same price of $59.95 each from classicperform.com. They look exactly the same except for the paint on the calipers. The originals where painted/powder coated silver. These are painted/powder coated black. The caliper housing, compared the standard bore US Brake 2.5” calipers and 2.0" Wilwood calipers, are a different casting. The piston looks to be stainless steel and comes with a dust boot installed. The piston diameter is 2.565" in diameter. These calipers came loaded with pads, slider bolts/pins, and hose fittings. You should be able to bolt these to your car, bleed the brakes, and drive. The piston cylinder side of the caliper is roughly the same size as the as the standard 2.5” bore caliper.

I recently purchased NEW, US Brake/Afco branded 2.5” standard bore metric calipers. They are $45 to $50 each online. The casting is not painted or powder coated. They come in a right PN 7241-9003 and a left caliper PN 7241-9004. They cannot be interchanged from side to side. The piston looks to be a cast steel/iron, unlike the CCP 2.75” and Wilwood 2.0” bore calipers. They are also 2.376" in diameter which matches stock advertised piston/bore sizes. The casting looks to be a stock casting and comes with a dust boot installed. It has all the markings of a stock calipers. This caliper came unloaded with no pads, slider bolts/pins, and hose fittings. It does come with the bleeder screws and bushing inserts for the slider bolts/pins. You will have to reuse your slider pins from your stock calipers and hose fittings. You will need to purchase new pads or reuse the ones you have on your car.

I also recently purchased NEW, Wilwood 2.0” small bore metric calipers. PN 120-9333. The price is round $80 each online. It is also a different casting from the other two. Visually the casting looks better and it looks to come with a stainless steel piston that is 1.981" in diameter. The casting comes bare with no paint or powder coating and they can be interchanged from the right and left hand side of the car. The piston cylinder portion of the caliper is physically smaller than the other two because of the reduced size of the piston. The piston bore and stainless steel piston look to have a better, tighter fit. The clearance is so tight there is no dust boot installed around the piston like the 2.75” and 2.5” bore caliper above. These calipers only come with a bleeder screw. It does not come with any other hardware. You will have to supply the slider bolts/pins, slider bolt/pin bushing inserts (I need to make sure this is possible), brake pads, and hydraulic hose fittings. All hardware should be able to transfer over from your original caliper. Please refer to this web page for more details. http://www.wilwood.com/PDF/Flyers/fl176.pdf

Out of the three calipers above, I was most impressed with the Wilwood calipers. These calipers have a very clean casting that weigh at least 2 lbs less than the other two calipers. The Wilwood website list a 2.75” bore version also that weighs just 5 more ounces than the Wilwood 2.0” bore versions (4lb 6.4oz v 4lb 1.6oz). These Wilwood iron calipers weigh roughly 1lb more than the Willwood comparable aluminum metric caliper with the 2.38” bore (4lb 6.4oz v 4lb 1.6oz v 3lb 6.4oz). I also suspect that the piston to bore clearances are just as tight as their 2.0" verson which will give the 2.75" version of the Wilwood caliper a larger piston that that of the CCP version. It theory this gives more clamping force.

 

[malibudave]

Pics of the CCP 2.75" Big Bore Metric Caliper

 

[malibudave]

Pics of US Brakes / AFCO 2.5" Driver's Side Metric Caliper