Booster push rod length adjustment - Chevelle Tech
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post #1 of 3 (permalink) Old Sep 3rd, 06, 9:07 PM Thread Starter
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Join Date: Sep 2006
Posts: 254
Booster push rod length adjustment


Car = 1970 chevelle SS 396

Bought the Delco Booster and new master cylinder that got repopped under the GM license. The manufacturer stopped sending the proper booster push rod. They send you the long one and not the shorter one. In the past, they sent you both rods and you just used the proper rod for your application. Their directions say that you should have an adjustable rod (I only had one solid rod), so the directions are not 100% helpful. I called the manufacturer, they said that the reason for the one rod is to save money. I told them that I would have gladly paid $5 for the proper rod!

The "tech" guy told me the shorter rod was 2 9/16 inches (he kind of measured one while I was on the phone). I did some of my own measuring and it seemed to be correct. This would allow the rod to just touch the master cylinder. So I cut it, rounded off the edge and assembled everything all the while checking and measuring. The rod just barely touch the back of the cylinder if at all.

Keep in mind that the brake system was compeletly restored. New lines, rotors, calibers, cylinders, etc. (I did not replace the proportion valves)!

I did have to remove the rod that was too long after it mistakenly got installed. Ok, my mistake. I had no pedal, something was obviously wrong. My GM mechanic neighbor verified that the rod was too long. The call to the manufacturer tech department verified the problem..

The car is on the road now and it just seems like I have no power brakes. I get immediate response when pressing the pedal, it just seems like its manual brakes and not power. Doesn't feel like my truck brakes, nor my daughters new Chevy nor my girlfriends 12 year old toyota for that matter.

I'm wondering if the rod is too long still? The car does stop evenly and quickly, I just don't get that cushy feeling that I associate with power brakes.

Is there a way of "testing" a power booster? I was wondering if I messed it up while removing the rod the first time. Is this just the way the brakes should be and I'm being too picky? I do not have another chevelle to compare it to.

I'm sure you folks can appreciate the hundreds of hours we put into our cars, I'm just trying to get it right.

Any advice is appreciated.
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post #2 of 3 (permalink) Old Sep 3rd, 06, 9:26 PM
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Join Date: Mar 2006
Location: Michigan (The Orange Barrel State)
Posts: 202
Re: Booster push rod length adjustment

I believe you did the right thing. I put a disc brake conversion kit on my '71 in August and had the same problem. I asked the guys on here, got the measurements and cut it, rounded it off and installed it. It works great!!! I measured 2 7/16, but I measured from the end to the o-ring seal, that's probably where you are getting the 1/8 in.

As for the "cushy" feeling. Mine doesn't have it either, it's very responsive, not much pedal at all. I love it!!! After driving the car for 17 years with drum brakes that didn't work any better than Fred Flintstone's brakes, not to mention the squirrley left and/or right pull the first few times out of the garage in the spring.

Sounds like you got it!!!

Jimmy Hotrod
Drive it like you Stole it!!!
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post #3 of 3 (permalink) Old Sep 3rd, 06, 10:43 PM Thread Starter
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Re: Booster push rod length adjustment

Thanks for the words of assurance Jimmy. Just got the car tags this Friday past. Took it out for its madien voyage this afternoon since the weather cleared up here after the hurricane.

Shook out a minor problem or two. She seems to be dialed in nice. Just want to replace the plug wires. Went to set the timing and the number one wire kind of fell apart. I put it back together and it was smoking after my first trial runs. I don't think it was firing correctly. Besides after seeing the wire all apart, the whole thing was pretty damn cheap.

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