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View Full Version : DYI: Squishy brake pedal fix!



HeresMyMind
05-04-2009, 11:18 PM
Ok so after upgrading all new pads and new fluid my pedal was still squishy and it was aggrivating me. last step was SS brake lines. But that can get kind of expensive... So i found out the proper way to fix this. it is actually how you adjust the brake booster rod on the pedal itself! here is a write up I copied from nhluhr on scooby mods, all actual write up applauding goes to him. I just did this at 11:00pm at night in 3 minutes and OMG the brakes feel amazing, just what i wanted!

-B

In the quest for a firm, responsive brake pedal, many people will spend lots of time and money on new pads, stainless steel lines, high end fluids, and even bigger master cylinders when it is very possible that they have overlooked the simplest little thing that will make a huge change to how the pedal feels underfoot. The best part? It's FREE!

Adjust your Brake Pedal's Free Play!

Tools Needed:
14mm Open-ended wrench (for adjusting brake light switch)
17mm Flare-ended wrench (for loosening locknut on booster rod)
Pliers (for turning booster rod to adjust)

https://sl-i.net/FORUM/images/imported/2009/05/tools-1.jpg

Before making any adjustment, first determine if this adjustment will help you. If you feel that your brake pedal travels a long distance before you get braking force (and it's not air in the line), you may have too much freeplay. Test freeplay on a car that is NOT running by first pumping the pedal several times to get rid of booster vacuum assist, then with approx a 2 lb force (easy press with 2 fingers) move the brake pedal. You will be able to feel an initial tiny slop in the linkage mechanism (from the clevis pin) and then the freeplay of a few mm, then you'll feel pressure from the master cylinder preventing you from pushing it further. The distance the pedal moves during the "freeplay" part of this movement is what you are trying to adjust. The spec is from 0.5mm to 2mm according to the service manual:

https://sl-i.net/FORUM/images/imported/2009/05/test_freeplay-1.jpg

https://sl-i.net/FORUM/images/imported/2009/05/view_of_parts-1.jpg
https://sl-i.net/FORUM/images/imported/2009/05/view_of_parts1-1.jpg

Use your 17mm Flare Wrench to loosen the locknut on the booster rod.

https://sl-i.net/FORUM/images/imported/2009/05/adjust_locknut-1.jpg

Use your pliers to turn the rod until freeplay is minimized. Don't go too far or your brakes will drag. You MUST maintain at least 0.5mm of freeplay to prevent dragging brakes! Remember, if you're trying to get less freeplay, you need to turn it so that less of the end of the rod sticks through the bracket on the back of the pedal.

https://sl-i.net/FORUM/images/imported/2009/05/adjust_rod-1.jpg

After adjusting rod, tighten the locknut down to keep the setting.

Then, test your brake lights to make sure they activate when you apply light braking pressure (if you are using light brakes in traffic and your lights don't come on, some moron will plow you). If you need them to activate sooner, adjust the position of the brake light switch by loosening its locknut and turning the other nut the proper direction to pull the switch up and back a little. This will increase the freeplay a bit. The key is to end up with between 0.5 and 2mm of freeplay between the switch and rod adjustments. Be sure to tighten the locknut down again after adjusting.

https://sl-i.net/FORUM/images/imported/2009/05/adjust_brakelight-1.jpg

That's it. Go get used to the new feeling of your brake pedal.

This method can also be used to adjust the relative height of the pedal to the other pedals, as well as adjusting the clutch pedal height!!

chuckthefuk
05-07-2009, 01:08 PM
Thank you very much for this great "DYI"... err... ummm "DIY" :grin:
- Chuck

nipper
05-07-2009, 01:29 PM
only adjust the brake rod lebgth after you have ruled out everything else. As an automotive engineer and a tech i rally can't endorse this. It can cause brake drag if not done properly, especially if it is a issue that is recent.

Squishy brake pedal can be a frozen or sticky caliper.


Also if you brake lines are soft enough to affect braking, your not fixing the issue, you are just hiding it.

nipper

2.5GT
05-11-2009, 08:36 PM
"Performance" brake pads, rotors, DOT 4/5 brake fluid, stainless steel brake lines...and call it a day. or upgrade to STi brembos.

Brakes aren't something to mess with when you're going 100mph and try to stop....