Definitive answer for adjusting engagement point of clutch?

[Dano]

Test drove a CB the other day and was amazed at how far off the floor the clutch pedal was before it hooked up, never drove one that had the pedal come up that far - I was concerned that maybe the clutch was worn so tried to get it to roll of a stop in third, and it stalled, which is the normal test I use for clutch wear if I'm not feeling obvious slipping or chatter.

It wasn't that the period of engagement took a long time on its way up, more so where it occured (high).

Tried to do a bit more research, and am a bit confused - some posts say that it's a pedal or pushrod adjustment issue, and others say it's a sign of a clutch that's on it's way out - can someone have the last word on this? I mean, if there is adjustment on the pedal and it's way up, is that becuase there's not much material left on the clutch, and adjustment is just a bandaid before the clutch completely goes? Or is this a normal adjustment item like rear brakes?

Also, one of the posts stated that one has to be really careful with the pushrod adjustment to not have the clutch permanently dragging, does anyone have anymore info on acceptable adjustment limits or specs?

These are the threads I found:

http://www.cb7tuner.com/vbb/showthread.php?t=157649
http://www.cb7tuner.com/vbb/showthre...=adjust+clutch
http://www.cb7tuner.com/vbb/showthread.php?t=197797

[reklipz]

I believe the clutch hydraulics are auto-adjusting. That means that as the disc wears, the slave cylinder piston sits a little bit further out, and the master cylinder automatically allows a little bit more fluid into the line to allow this.

You can put more pressure on the slave cylinder by extending the master push rod, effectively allowing you to get that last little bit of the clutch disc as/before it starts slipping.

Adjust the push-rod and pedal height to spec, and if the clutch slips, it's time for a new clutch disc.

--

Edit: Sorry I don't have any specs off-hand. I can look tomorrow if you remind me.

[oyajicool]

------You can put more pressure on the slave cylinder by extending the master push rod, effectively allowing you to get that last little bit of the clutch disc as/before it starts slipping.------------

Changing length of rod does not increase operating pressure. Doing so changes the height of clutch pedal.
See below,,,,,,,,,

[reklipz]

Changing length of rod does not increase operating pressure. Doing so changes the height of clutch pedal.

I was thinking one could make the clutch pedal height as high as possible, and extend the push rod as far as possible. This would give you a longer throw than "stock," effectively pushing the slave piston further out, or increasing the pressure (because the slave piston will be held constant at some point). Thinking about it though, this won't allow you to get any extra clutch material, because when the clutch slips it's because the pressure plate springs can't apply anymore pressure (reached their limit; the clutch disc is too thin), nothing to do with the hydraulics/disengagement mechanism. Brain fart!

My clutch has always seemed mal-adjusted, so today I tried to adjust it to spec. Presently, when releasing the clutch, there is a bit of a "hinge-point"; sometimes I have to help the clutch pedal the "rest of the way" out, about an inch until it's end of "extended" travel. You can feel this "hinge-point" when pressing the pedal as well. Anyway, this is what I was trying to eliminate.

First, I couldn't get the specified 8.27 inch pedal height. This is with the switch all the way backed out, and the master push-rod disconnected from the pedal.



I figure this was due to "old parts", and perhaps the bracket/pedal have sagged/warped from 20 years of use. I gave it a good push/pull/wiggle-waggle and was able to get ~9 inches of pedal height. Next was adjusting the push-rod length and ensuring a bit of master piston/push-rod play (1 to 7 mm). Here's what I ran in to, first half is how the pedal acted before adjustment, and the second half after adjustment (I extended the push-rod just a tad). It's hard to tell from the video, but for the first half, every time the pedal "snaps" all of the way out, that is because I help pull it with my hand/thumb after a moment of it sitting still.



So, I wasn't able to eliminate the hinge-point, but I was able to keep it from "sticking" at the hinge-point. The pedal travels an inch to 1.5 inches from extended to this hinge-point, and during that travel, the push-rod moves ~0.5 cm total. If I adjust the push-rod the other direction (shorten it), the hinge-point just adjusts in closer to the floor, and I have to assist the pedal to return from it (like before). It also obviously adjusts the pedal height to be shorter than the specified.

Next up was to check the pedal throw. This is about 6 inches if you include the 1-1.5 inches of throw before the "hinge-point." The disengagement point is also below the specified 3.54 inches. Here's another video, apologies again for the shaky-cam.



So, how can I eliminate the "hinge-point" piece I'm describing? Is this simply how the mechanism works and it was mal-adjusted before, or are my parts out of alignment and I need a new pedal/pedal bracket?

[oyajicool]

[QUOTE=reklipz;3150821]---------------------------First, I couldn't get the specified 8.27 inch pedal height. This is with the switch all the way backed out, and the master push-rod disconnected from the pedal.

-------------------[QUOTE]

It doesn't appear that you are measuring the height correctly.
Compare your photo and the page from the manual again.

I have no clue about "hinge-point".

I adjusted my clutch pedal height to suite my taste, without reading what the manual says. It's been great for I don't know how long,,,,,,. I'm sure you can do the same. There's not much to adjust anyhow.

[reklipz]

It doesn't appear that you are measuring the height correctly.
Compare your photo and the page from the manual again.

Holy hell, talk about a brain fart. I seriously thought they meant drop a plum bob to the floor. I see now that the minimum engagement height spec is measured to the "floor" as well, and I knew they meant the back angled panel of the floor, not the... floor.

I suppose I will have to see if I can readjust and get both measurements within spec. The "hinge-point" thing may disappear after that, though I doubt it. I will take a better video of different push-rod adjustments to better explain if I still have the problem.

Thanks for the clarification there oyajicool.

[oyajicool]

You are welcome and good luck with your work.

[Mishakol129]

Holy hell, talk about a brain fart. I seriously thought they meant drop a plum bob to the floor. I see now that the minimum engagement height spec is measured to the "floor" as well, and I knew they meant the back angled panel of the floor, not the... floor.

I suppose I will have to see if I can readjust and get both measurements within spec. The "hinge-point" thing may disappear after that, though I doubt it. I will take a better video of different push-rod adjustments to better explain if I still have the problem.

Thanks for the clarification there oyajicool.

I too am having this same thing happen, I don't know if its normal or not. Just like your video there is too much play (or seems to be too much) in the clutch pedal spring (or whatever). I tried adjusting the pedal but both all the way out and all the way in, it did nothing. Perhaps its normal? I don't know.


EDIT:

Nevermind, I fixed it.

[oyajicool]

why don't you tell him how you fixed it?

[Carolinasfinest]

maybe undo the spring so it wont pop back up? i was doing that adjustment to mine this morning and all it did was give me HELLA free play. all i really wanted to do was make the clutch pedal and brake pedal even. so i just put it back cause its just a bitch to be under the dash like that.