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2017-01-06 Tiburon - Clutch Hack

By
booneylander
840

So right off the hop, the car's clutch felt super wonk. I knew the clutch was nearing the end of it's life because it would engage right at the very top of the pedal travel. However, there was something else, an intangible disconnection from the pedal, the action always felt kind of inconsistent. When I had inspected the car before buying, I had noted that the clutch fluid looked more like a stout than a DOT4, so I figured moisture and junk in the fluid was the culprit.

I initially flushed the system out with fresh fluid, but the pedal action felt identical.

Whilst searching for some way to adjust the clutch travel so that I could hopefully get a tad more life out of the poor worn clutch disk, I came across this hack mod and decided it was worth a shot.

To gain access to your clutch slave cylinder, you'll remove the airbox lid by undoing the clamp at the MAF, and cutting your airbox-lid retaining ziptie (the car came without spring clips - don't worry, they're in the mail). Next remove your air filter and undo the 2 remaining bolts in the bottom of the airbox. I say remaining because my 3rd bolt was missing. I ordered a new one, then noticed during this procedure that whatever bracket it would have been fastened to under the airbox was missing. Normally these cars come with a resonator box deal which on mine had been replaced with a straight-pipe, so I'm guessing that's my missing connection.

Now you can remove the lower half of the airbox and you'll see your clutch slave cylinder sitting there.

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Now you'll want to remove the slave cylinder from the car. To do this, pull the clip out from the pin where the pushrod is attached to the lever arm. You'll notice in my second pic the configuration of the clip - this wasn't mentioned in the guides I had seen online and I initially pulled on the clip and went "why isn't this thing coming out", until I had a closer look and noticed that it locks into the pin. To remove it, just spread the outside wire that goes around the pin then pull back on the end. Easy peasy.

Next you'll want to just crack the banjo bolt loose while the slave cylinder is still firmly attached to the car. Apparently, as you can see in the pics, I think someone had already attempted this procedure using most likely an SAE box end wrench or something, which Americans are prone to do because they can't get their heads around the metric system, and they'd stripped the head just about completely round. With a little patience and a 6-pt socket in the proper size (11mm) I managed to crack the banjo loose without just going round and round.

Now you can go ahead and undo the 2 bolts that fasten the slave cylinder to the transaxle. To my surprise, as soon as I took the second bolt out, the slave jumped back by as much as you can see in the pic, and the pushrod extended from the slave by the same amount. I can only assume they've spring-loaded the slave cylinder to make the clutch pedal feel lighter, but annoyingly, this means that even when you've let the clutch out completely, there is still a bit of preload on the lever arm and therefore, on the pilot bearing and the pressure plate... I'll address this later as you'll see.

With the slave loose, pull the pin from the pushrod/lever and pull the slave out of the car. At this point you can remove the banjo bolt and feed line completely. If you have any fluid in the reservoir, it's all going to come out the hose unless you fasten it up so the tip is above the reservoir. Make sure the lowest part of the hose is below the reservoir though, or you'll back-feed air into the master cylinder.

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Now that you have the slave cylinder off, use a magnet to fish out this little cap and spring setup. Now, what this does is, when you push the clutch pedal down, the fluid compresses the spring and fills the slave, disengaging the clutch. But then when you release the clutch pedal, the cap presses itself against the banjo bolt and restricts the back-flow of fluid into the master cylinder. The effect that has is, it slows the return of the slave, and slows the engagement of the clutch.

Now, if the clutch in the car was new and the friction point was low in the pedal travel, and/or if I was a rookie at using a clutch, I can totally see how this could make the car easier to drive. For someone that just dumps the clutch every time, it would soften the engagement and keep them from neck-snapping their passengers or stalling the car. But, in my case, where the clutch engages right at the top of the travel, if I push the pedal to the floor and then release it back out to where it should be engaging, there is a significant lag before the slave cylinder catches up the where my foot is, so in that time, I'm left thinking "how come I'm not starting to hook up here, maybe I need to ease the clutch up a bit further than I thought" so I do, and keep inching my foot up, until the clutch starts to engage. Problem is, by the time it starts to hook up, my foot is now well past the friction point, so it starts to hook up more than I want it to , meaning that I have to push the pedal back in somewhat to compensate. All this shenaniganry translates into a clutch that feels super inconsistent.

Pulling this cap and spring out means that as soon as I feed the pedal out I'll get the enagagement I'm looking for. Sean happy.

Now after reading my rant, you can re-install your line and banjo bolt and snug it up a bit before fastening it back to the transaxle and giving it a final snug.

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Now it's time to get a little crazy. I know Q20V and Ripcurl in particular will love what I'm about to do to my OEM parts.

So, remember the preload I was talking about? How when I undid the slave cylinder it popped back an inch? Well, when I manually pressed the slave towards it's mounting point, I observed that the lever did move somewhat, meaning that the clutch was always sitting with a tiny bit of preload on the pressure plate. Remember my clutch was worn right out? Yeah this is how we're going to get a little bit more life out of it.

Simple really. I just took a hacksaw and cut the tip of the pushrod off. Now normally I'd use some more powerful tools, but I'm in Hawaii and pretty limited as to what I have on hand. I just took a bit off. But enough to significantly reduce how much preload was on the lever, in effect, letting the pressure plate travel just a teeny tiny fraction of a bit closer to the clutch disk and apply just that teeny tiny fraction of a bit more pressure on it.

Now I wanted to match the rounded profile on the tip of the pushrod, but having no power-grinding tools, I had to perform the match by hand using just a file. So, I sat on my porch in the Hawaiian jungle, not unlike Tom Berenger in the jungles of Panama in Sniper, just filing away at the tip of my bullet until it was just the way I wanted it. I followed up with some sandpaper to give me a nice smooth finish that would undoubtedly unlock about 8hp or more. I greased that mofo up and stuck it back in there, and now the clutch is much better, in both feel and holding power. I'm still going to drive it like a grandma mostly because I want to make sure the clutch hangs in there until I sell the car, but at least the holding power is there in case I need it, and it will prevent it from slipping a tiny bit and killing the disk prematurely. Woot!

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This one time, circa 1999, I noticed some surface rust on my buick's strut tower. I thought I should really take care of that, otherwise it will inevitability pose an irreparable safety issue. Then I looked at how to remove rust, and I would have needed to grind away OEM metal. I thought to myself, I cant do this. I'll just wait for a clean donor car where I can grind/drill out the tack welds and replace the whole assembly. 14 Buicks and 15+ years later that day never came. - ripcurl January 19th 2017
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Oh yeah! Once you get that sucker back in by reversing the removal process, make sure you give it a good bleed. I used a Mityvac that I purchased just for the job. I'm not really very impressed with the mityvac to be honest, but oh well, I got the job done. To bleed, just pump the clutch pedal several times, then hold it down either by throwing an assistant at it, or by doing what I did which is to adjust an extendable paint-rolling rod to the correct length to wedge it between the pedal and the door latch, then crack the bleed screw to evacuate the fluid. Then re-pump the clutch pedal and do it again until the action feels good and the fluid coming out is clear and free of bubbles.

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