The S-10 manual brake conversion - factory parts

[440shorty]

After reading about manual brake conversions, I decided to check out the S-10 setup, which is far more common than the early A/G body ones. Here is what I found out, and how I modified the S-10 parts to fit my '81 A body Pontiac. S-10s were available with manual brakes as late as 1988, the year of the truck that donated its parts to my project. Usually they also are stick trucks, and often have manual steering too. At least in central PA, they are fairly common, and are being retired more often now.

Here are the parts that make up the manual brake setup:


Left to right: The A/G body pedal, with the S-10 stud already installed in top hole

The A/G body pedal hanger bracket

The S-10 pushrod and retainer assembly. Here is a breakdown of those parts:


The S-10 master cylinder with proportioning valve and bracket.

Minor modifications have to be made, but they are not difficult, and the result is a setup that can be serviced at the local auto parts store.


Since attachments are limited to three per post, I can detail each mod as a separate post.

440shorty

 

[440shorty]

Since the brake booster has studs, and the factory S-10 pedal hanger also had studs, I bought metric bolts at the hardware store and had them welded to the A/G pedal bracket so that they protrude into the engine compartment. That way, it still is a one-man job to service the master cylinder. The stock jam nuts are then used as before, only on the engine compartment side.


Also, it can been seen in the above picture that the pushrod stud in the top hole lines up with the top two studs where the master cylinder will be bolted.

The S-10 pedal was totally different than the A/G one:


The S-10 pushrod has a larger diameter hole for the pedal end than the booster's hole, but the stud diameter (once removed from the pedal) is actually smaller than the hole in the G-body pedal. This was easily overcome by carefully removing the stud from the S-10 pedal with a rotabroach, then a hole saw, then grinding off the remaining pedal material, leaving the stud with the mushroomed end intact. The stud was a tight fit, then I had it welded for good measure.

The firewall required minor trimming to fit the master cylinder at the top. The stock block-off plate was used as a template to mark the firewall, and snips were used to trim for clearance:


440shorty

 

[440shorty]

The S-10 pushrod was way too long, as can be seen below. It is actually hitting the brake switch bracket.


By mocking up the parts off the car, an accurate measurement was made from the back of the master cylinder to the pushrod stud on the pedal with the pedal held back against the brake switches, closing them. It was determined that 2.4" was to be removed from the pushrod and the pieces welded back together to make a pushrod measuring 3.8" from the master cylinder end to the center of the pushrod hole.

IMPORTANT The brake pushrod is hardened steel. The proper welding rod must be used to ensure a strong safe weld. My neighbor is a welder and used the proper rod. DO NOT just MIG it together!

Here is the pushrod subassembly with the shortened pushrod

440shorty

 

[440shorty]

The S-10 manual brake master cylinder has a smaller diameter piston and a smaller diameter register on the back, which fits the pushrod retaining cup. The A/G- body power brake master cylinder's larger diameter register will not fit the retaining cup, so an S-10 master cylinder must be used. I do not know if there is a manual brake A/G body master cylinder, but it probably would be iron anyway, like the original master cylinder that came on my '81.

Here is a picture, from the outside, of the S-10 parts installed, ready for the master cylinder:

I had already swapped an S-10 master cylinder and combination valve onto my Pontiac, eliminating the old combination valve down below on the frame rail. The rear brake line and combination valve had both gone bad anyway, so I took the opportunity to save weight with a cleaner factory install. The brakes worked great with the S-10 master cylinder and combo valve. The angle of the reservoir was not an issue.


The brakes work great now, except for the bad front brake lines. I'm glad that I found those before they let go (one is leaking) because a brake failure caused the damage that led to the Gold nose in the first place!

I can answer any questions and welcome comments. I do not mean to take away from anyone's business selling aftermarket parts. I drive my cars a lot and cross country, so I tend to try to use common factory parts whenever possible. Plus, I'm cheap. Happy parts hunting!

440shorty

 

[Toner283]

=D> Thanks Man, this info is very helpful. I plan on doing this conversion to my car & this helps a lot, it is always great to see it done & the pics are great.