Manual Brake Conversion with Pictures

malibudave1978

Amateur Racer
Jun 8, 2004
226
0
0
Houston, TX
I just finished up upgrading the brakes on my father’s 1980 El Camino. This is a daily driver that I am testing several different master cylinders for a manual brake conversion swap. His brakes worked good before exchanging out all the parts, but I wanted to take out most of the variables when testing master cylinders. First and foremost, I wanted to make sure this 1980 El Camino did not have quick take up front brake calipers. In my research, quick take up calipers will make it difficult do get good pressure to the caliper when using manual brakes.

Here is the rundown of the parts I used:
• Speedway Motors Big Bore Metric Calipers - PN# 91031040 $59.99 each
• Bendix Titanium metallic front brake pads (FF Rated) - PN# MKD154 $38.22
• Turned the stock rotors $30 Local Auto Parts Store $15 each
• Edelbrock/Russel Stainless Steel Braided Flex Lines PN# 692100 $54.80
• Wagner 7/8” Wheel Cylinders from an manual brake S10 PN# F110261 $13 each
• Wagner Thermo Quiet Rear Shoes (EE Rated) - PAB514R from O’Reilly’s Auto $32.99

The Speedway Motors big bore metric calipers (2.75” bore v 2.38” bore standard) came with brake pads, but the pads did not have a rating on them. I DID NOT want to use a brake pad that would need a lot of heat to be effective. The weight difference between the two calipers is less than ½ of a pound. This is a daily driver and not an autocross car, so I chose the Bendix Titanium pads because my research and reviews showed them to have good cold clamping friction. Based on the EE rating, the rear shoes should also have good cold stopping abilities. Look on the pads or shoes when you buy them to make sure they have a rating on them. The higher up the alphabet you go the hotter the pads will have to be to work effectively. Pads or shoes with no rating on them should be avoided.

It was surprising to me to find a 24mm strait bore aluminum master cylinder on this 1980 El Camino. I didn’t know they made aluminum ones with a strait bore for g-bodies. I had always been under the impression, because it was aluminum, that this was a step bore master for quick take up calipers. I do know for a fact that any NEW replacement master cylinders for g-bodies will for than likely be cast iron. So if you want aluminum master cylinder for power or manual brakes that bolt up to your brake lines, a rebuilt master cylinder may be your only option.

I changed out the 30 year old rubber brake lines with the braided stainless. The front lines were a little longer than the originals, but I routed them so they were not touching any suspension pieces. The rear was a little more difficult to replace because the clip that holds the rubber line to the frame was difficult to get at. The new braided rear line was fairly easy to install also.

The hardest part to the entire swap was installing the rear wheel cylinders. Getting the clip off was not too bad, but getting the clip back on was a pain. I did it with two c-clamp, and open ended wrench, and the lid off of an old battery terminal cleaner (don’t ask for these details because I do not recommend doing it this way. G-H-E-T-T-O).

After the system install, bleeding the fluids, and bedding in the pads and shoes I took it out for a spin to test the brakes with the same master cylinder and vacuum booster from the original test with the original brakes. Even though I was able to easily lock up all four wheels, it seems to have a little more pedal travel before you could feel the brakes start to grab. I believe this has to do with the increased piston area in the front calipers and rear wheel cylinders while using the strait bore 24mm master cylinder. The 24mm master cylinder will have more pedal travel to fill the extra volume of fluid required by the calipers and wheel cylinders.

If keeping the vacuum booster, it might be best to step up to the step bore master cylinders that are used on the 1981 and up g-bodies. The primary bore is still 24mm, but it also has a larger step bore of 36mm that will increase the volume of fluid to the larger calipers and wheel cylinders.

For the manual brake setup, I am going to test the original strait bore aluminum master cylinder with 24mm bore. Stay tuned for an update within the next month.
 

malibu795

Pro Stocker
Apr 17, 2005
1,497
4
38
spgfd ohio
Re: Upgraded Stock Brakes on a 1980 El Camino

I had a brain fart back. which port on the mg is for the front brakes?. o think I hotone backwards
 

malibu795

Pro Stocker
Apr 17, 2005
1,497
4
38
spgfd ohio
Re: Upgraded Stock Brakes on a 1980 El Camino

and of course i put them backwards...... with old straight bore mc didnt really matter... now i got a stepped mc of a monte carlo.
 

malibudave1978

Amateur Racer
Thread starter
Jun 8, 2004
226
0
0
Houston, TX
Re: Upgraded Stock Brakes on a 1980 El Camino

malibu795 said:
and of course i put them backwards...... with old straight bore mc didnt really matter... now i got a stepped mc of a monte carlo.

How did you have the the lines reversed? They are two different sizes.
 

malibu795

Pro Stocker
Apr 17, 2005
1,497
4
38
spgfd ohio
Re: Upgraded Stock Brakes on a 1980 El Camino

malibudave1978 said:
malibu795 said:
and of course i put them backwards...... with old straight bore mc didnt really matter... now i got a stepped mc of a monte carlo.

How did you have the the lines reversed? They are two different sizes.
ripped the entire rusted out brake lines off the car and started with a roll or 3/16, 5/16 line and rusell braided brake lines.
 

Wile E

Dragway Regular
Aug 11, 2003
1,075
0
0
Central WISC
Re: Upgraded Stock Brakes on a 1980 El Camino

Hey malibudave1978, nice post. Question... you wrote:
The Speedway Motors big bore metric calipers (2.75” bore v 2.50” bore standard)
I thought the standard bore was 2.38", so wouldn't the 2.50" also affect the brake bias-and peddle travel?, and the 2.75" even more? Or did some later year G-bodys use the larger 2.50" calipers?
Did not know the s-10 step up bore size was 31.5, that may be the direction I'll go also.
Good job posting those part #'s
Let us know how this turns out.
 

malibudave1978

Amateur Racer
Thread starter
Jun 8, 2004
226
0
0
Houston, TX
Re: Upgraded Stock Brakes on a 1980 El Camino

Wile E said:
Hey malibudave1978, nice post. Question... you wrote:
The Speedway Motors big bore metric calipers (2.75” bore v 2.50” bore standard)
I thought the standard bore was 2.38", so wouldn't the 2.50" also affect the brake bias-and peddle travel?, and the 2.75" even more? Or did some later year G-bodys use the larger 2.50" calipers?
Did not know the s-10 step up bore size was 31.5, that may be the direction I'll go also.
Good job posting those part #'s
Let us know how this turns out.

I thought stock was 2.50", but since you measured them, stock is 2.38"

The manual brake conversion went well when using the manual brake hole that is already predrilled in the factory vacuum booster power brake pedal. I kept the stock , 31 year old, 24mm master cylinder that came with the stock power boosted brake system. I kept the 24mm master, for now, because I upsized the front calipers and wheels cylinders. It stopped the car ok, but I felt I still had too much pedal travel and I couldn't get the front brakes to lock up. I am going to rebleed the calipers, unbolted from the spindle, to point the bleeder screws up at the 12 o'clock position. If this doesn't do the trick, I will bolt on a brand new manual brake master cylinder from a 1978 to 1980ish g-body. This master cylinder has a smaller bore which should give me higher pressure at the pad.

Before manual brake conversion:
IMG_0317.jpg

IMG_0318.jpg

IMG_0319.jpg


After manual brake conversion:
IMG_0345.jpg

IMG_0346.jpg

IMG_0347.jpg
 

Wile E

Dragway Regular
Aug 11, 2003
1,075
0
0
Central WISC
Re: Upgraded Stock Brakes on a 1980 El Camino

Well it looks like 2.50" will be an tiny upgrade for me if I go with stock style calipers, I mic'd my original ones and the caliper piston does come out to 2.38", o.d. If you do go with the s-10 master cylinder, I'm curious to see how that works out.
Nice work.
 

malibudave1978

Amateur Racer
Thread starter
Jun 8, 2004
226
0
0
Houston, TX
Re: Upgraded Stock Brakes on a 1980 El Camino

Wile E said:
Well it looks like 2.50" will be an tiny upgrade for me if I go with stock style calipers, I mic'd my original ones and the caliper piston does come out to 2.38", o.d. If you do go with the s-10 master cylinder, I'm curious to see how that works out.
Nice work.

I stand corrected. I was under the impression that it was 2.50".
 

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