Clutch Pedal Low After Replacing Brake Booster on S3 - Alfa Romeo Bulletin Board & Forums
 
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post #1 of 15 (permalink) Old 04-25-2016, 05:24 PM Thread Starter
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Clutch Pedal Low After Replacing Brake Booster on S3

I replaced my leaking brake booster on my 1987 S3 and now my clutch pedal is 2 inches below my brake pedal. Before the repair my clutch pedal was slightly lower than my brake pedal (~0.5 inches). The clutch still engages and I can change gears without grinding. When I changed the brake booster, I did not disconnect either the clutch or brake lines, but I moved them aside instead.

Last year I changed a broken clutch pivot with a reinforced one so I don't think that is the problem. Also, when I pull up on the clutch pedal it does not stay in a higher position.

2 1/2 years ago I changed the clutch slave cylinder and flexible line. I don't see any leaking clutch fluid from either the master or slave cylinder and the fluid reservoir is topped off.

Can anyone suggest what might be wrong? I appreciate any help that is offered.
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Kim - 1987 Spider Quadrifoglio (~170K original owner miles)
Huntsville, AL
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post #2 of 15 (permalink) Old 04-25-2016, 05:45 PM
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Originally Posted by bongju View Post
I replaced my leaking brake booster on my 1987 S3 and now my clutch pedal is 2 inches below my brake pedal. Before the repair my clutch pedal was slightly lower than my brake pedal (~0.5 inches). The clutch still engages and I can change gears without grinding. When I changed the brake booster, I did not disconnect either the clutch or brake lines, but I moved them aside instead.

Last year I changed a broken clutch pivot with a reinforced one so I don't think that is the problem. Also, when I pull up on the clutch pedal it does not stay in a higher position.

2 1/2 years ago I changed the clutch slave cylinder and flexible line. I don't see any leaking clutch fluid from either the master or slave cylinder and the fluid reservoir is topped off.

Can anyone suggest what might be wrong? I appreciate any help that is offered.

well... on mine the clutch master bolts to a bracket that is welded to the brake booster the position of that bracket relative to the bulkhead will determine where the pushrod clevis ends up... so... all that being true and assuming you didn't screw with the push rod length either the bracket is welded wrong or its the wrong brake booster or something... the fundamental issue is that the clutch master is now too far away from the pedal attachment. there is a lot of adjustment in that push rod but i don't know if its enough to fix your issue. if you DID screw with that during disassembly then thats where you screwed up putting it back.
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post #3 of 15 (permalink) Old 04-25-2016, 06:34 PM Thread Starter
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Thanks Steve. I didn't intentionally adjust the push rod, but I will check it's length vs. the service manual just to be sure. I will also compare the mount position of the clutch master on the old brake booster vs. the position on the new one.

Kim - 1987 Spider Quadrifoglio (~170K original owner miles)
Huntsville, AL
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post #4 of 15 (permalink) Old 04-26-2016, 02:28 AM
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Originally Posted by bongju View Post
Thanks Steve. I didn't intentionally adjust the push rod, but I will check it's length vs. the service manual just to be sure. I will also compare the mount position of the clutch master on the old brake booster vs. the position on the new one.
well... at the risk of being struck down by lightning, i would suggest that what the manual says at this point is irrelevant. if you have sufficient threads left at the clevis to wind it out a bit and not get too near the end , then use that to position the pedal where ever you want. you need at least 8mm of threads in the clevis when you are done and you don't want to be bottoming the piston in the cylinder by over throwing it.. either way, the solution should be quite clear once you look at it .
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post #5 of 15 (permalink) Old 04-26-2016, 12:33 PM
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They teachers at the factory Alfa classes told us to just adjust the clutch pedal height to match the brake pedal.

If an aftermarket booster was used. The rod inside the booster could be a different length then the original ATE booster.

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post #6 of 15 (permalink) Old 04-26-2016, 12:38 PM Thread Starter
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They teachers at the factory Alfa classes told us to just adjust the clutch pedal height to match the brake pedal.

If an aftermarket booster was used. The rod inside the booster could be a different length then the original ATE booster.
Yes, I used an aftermarket booster from Vick Auto. So are you saying the rod inside the booster may have raised the brake pedal?
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post #7 of 15 (permalink) Old 04-26-2016, 12:49 PM
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Yes, I used an aftermarket booster from Vick Auto. So are you saying the rod inside the booster may have raised the brake pedal?
That would be my guess since its the only thing you have change.

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post #8 of 15 (permalink) Old 04-26-2016, 01:21 PM
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The bolt that attaches the booster to the brake pedal arm has an offset shoulder, meaning there are two ways to install it, and this affects the position of the pedal arm.


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post #9 of 15 (permalink) Old 04-26-2016, 01:23 PM
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That would be my guess since its the only thing you have change.

the brake pedal has a positive stop for the return , doesn't it ? no way that could be higher and if that arm is too long it collapses the cylinder past the fluid return ports and will soon lock the brakes solid as you drive ( i have seen this and boy were THOSE people confused ) ... and if the brake pedal were higher , thats the first thing your leg would notice when you get in the car... you would say... " gee why does THIS feel so much different..."
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post #10 of 15 (permalink) Old 04-26-2016, 06:07 PM
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Some aftermarket boosters the arm that attaches to the brake pedal is adjustable. If this is the case in yours this would be the cause of your pedal being higher.

1969 1750 Spider Veloce w/dual webers, 1969 1750 Berlina, 1971 1750 Spider Veloce w/ dual webers, 1985 Spider Veloce 23,000 orig. miles, {Two} 1986 Spider Veloces, 1987 Spider Veloce bought new, 1988 Quadrifoglio, 1991 164S, Plus several more. I think they are breeding.
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post #11 of 15 (permalink) Old 04-27-2016, 02:56 AM
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Some aftermarket boosters the arm that attaches to the brake pedal is adjustable. If this is the case in yours this would be the cause of your pedal being higher.
even if the arm is longer, how can that move the pedal up if the pedal is already up against a rigid positive stop ? if the arm is longer then that extra length MUST get absorbed into the cylinder by moving the piston off its standing return position .
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post #12 of 15 (permalink) Old 04-27-2016, 07:31 AM
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even if the arm is longer, how can that move the pedal up if the pedal is already up against a rigid positive stop ? if the arm is longer then that extra length MUST get absorbed into the cylinder by moving the piston off its standing return position .
stevesxm has a good point here. The brake light switch limits the upward movement of the brake pedal. Once that switch reaches the limit of its travel - e.g., turns the brake lights off - you can't move the pedal any higher without bending the switch bracket.

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post #13 of 15 (permalink) Old 04-30-2016, 11:35 AM Thread Starter
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I finally had time to look at the clutch push rod today. The locknut against the clevis was loose so the threaded rod may have rotated. The total length was less than 5 inches and the specification is 5.28 inches. When I set the clutch push rod to the correct length (and tightened the locknut), the clutch pedal came up to near the brake pedal, which is the same position as before I started this repair.

Thanks for all the help and suggestions.

Kim - 1987 Spider Quadrifoglio (~170K original owner miles)
Huntsville, AL
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post #14 of 15 (permalink) Old 04-30-2016, 11:43 AM
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I finally had time to look at the clutch push rod today. The locknut against the clevis was loose so the threaded rod may have rotated. The total length was less than 5 inches and the specification is 5.28 inches. When I set the clutch push rod to the correct length (and tightened the locknut), the clutch pedal came up to near the brake pedal, which is the same position as before I started this repair.

Thanks for all the help and suggestions.

ok kids, whats the object lesson here ?

hint... ALWAYS look at the way things are BEFORE you take them apart so .... ????

hint number two... so that they go back together the same way...
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post #15 of 15 (permalink) Old 02-06-2017, 03:35 PM
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I'm not sure if this was resolved but I've just changed the booster in my Super and had the same issue with low clutch pedal. The reason is the clutch master cylinder mounting bracket is in a different location on aftermarket boosters. Its set back a bit so if you do not change the distance of the clutch clevis, your pedel will be too low.
The booster in the photos is from Classic Alfa and works great.
Top photo - after market


Original booster

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