Clutch throw adjustment question

Matt McGrain · **Posted:** Tue Mar 01, 2011 11:59 pm

I think I found the culprit for a bad occasional 1-2 shift grind under high rpms. Apparently shortening the throw manually can eliminate this, but my question is, couldn't this be detremental to clutch life when you're basically applying additional pressure to the cylinder? Kind of hoping not...

Quick photo diy from the 8th Civic forums

-Matt

Karl Shultz · **Posted:** Thu Mar 03, 2011 8:51 pm

Matt, I don't think you'd be applying additional pressure; you'd just be moving a larger amount of fluid. Pressure in terms of line pressure, I believe, would be the same, or nearly so.

Matt McGrain · **Posted:** Thu Mar 03, 2011 10:05 pm

That's actually what I found out is the case. I tightened it up a touch and the pressure is a tad firmer but I still managed to grind second gear (starting to think the shift has to be a little precise positionwise) doing an autocross style 1-2 near the redline. We'll see if it helps but it did take out some of the 'slop'.

DickRasmussen · **Posted:** Thu Mar 03, 2011 10:26 pm

???
I'm confused. The only reason I can think of for increasing clutch travel is if there isn't enough to allow full release.

Are you sure this isn't the common problem of "beating the syncros" with a FAST high rpm upshift? Especially if the syncros are worn from lots of up or down shifts with big rev differences between gears due to high rpm. Been there, done that, got to replace syncros in my Lotus when one too many high rpm downshifts took a syncro past the wear limit. When that happened even upshifts had lots of grinding unless I shifted slow enough to let the gears "spin down".

Dick (who double clutches on the street to save the syncros for when there is no time to double clutch)

JamesShort · **Posted:** Thu Mar 03, 2011 10:29 pm

Matt, maybe you didn't see my 8th civic post. I have 12 qts of Redline MTL arriving tomorrow. When I do my konis, you should come over and let's put some good fluid in your gear box. That OE Honda shit shears and looses it's add-pack fast. I'm going to do my trans fluid yearly. I owe you 2 qts of MTL for using all your V710s up at the TnT

.

Charlie Guthrie · **Joined:** Thu Aug 28, 2003 8:14 pm **Posts:** 832

I took a look at the link to the Honda forum and all that they are doing is compensating for wear in the linkage by adjusting the push rod clevis on the brake master cylinder. There is a danger in doing this if there is inadequate free play in the pedal because the clutch will not fully engage and will be slipping slightly. Also you run the risk of hyper extending the clutch pressure plate if the resulting travel at the slave cylinder is too great (that's why many high performance and race cars have clutch pedal travel stops).
In my experience you are $ ahead by making sure that the free play and the travel are in accordance with the factory specs. I have had to re-bush a few clutch pedals and replace the pin and/or the clevis on the clutch master cylinder to take out the looseness. This used to be a real problem with MG cars (and most British cars).
Charlie G

Steven Carter · **Posted:** Thu Mar 03, 2011 10:50 pm

Karl Shultz wrote:

Matt, I don't think you'd be applying additional pressure; you'd just be moving a larger amount of fluid. Pressure in terms of line pressure, I believe, would be the same, or nearly so.

True. Threaded adjustable clutch rod is similar to what my old Z has. When I restored it, the "OEM exact specification" rod was, in fact, not. Went to engage the clutch and had zero resistance in the pedal. Adjusted it until it could move a large enough volume of fluid to engage the hydraulics and move the clutch. IMO, little risk to wearing out clutch components.

edit: Charlie, that's a good point about the PP. I think, though, the risk to the synchros/transmission with a high rpm 1-2 shift would be greater than wearing out the spring steel on a replaceable (and cheaper) pressure plate. But what do I know? My car shifts like buttah with its Legacy GT gears. But the engine blows up at random times, so there's that.

Charlie Guthrie · **Joined:** Thu Aug 28, 2003 8:14 pm **Posts:** 832

OH yeah, one more thing...don't put wear inhibitors in your gear oil. The synchros work on friction and viscosity shear. I made the mistake of adding powdered graphite into a manual gearbox since it had done such wonderful wear inhibiting duty in the engine of my Sunbeam Alpine. The gearbox would not shift into any gear at any speed without grinding gears. A quick flush of the gearbox and fresh gear oil and everything was back to normal.
The same goes for molybdenum sulfide (MOLY) lubricants...they're just not for synchromesh transmissions.
The suggestion to change the tranny oil may be a very good suggestion, especially if the oil has some age on it. Viscosity modifiers can break down after a while.
Charlie G

DickRasmussen · **Posted:** Thu Mar 03, 2011 11:23 pm

Interesting technical info from Redline.

MTL is appropriate for trans which use gear oil.
http://www.redlineoil.com/content/files ... 20Info.pdf

However, lots of manual transmissions including Tremecs in Pony Cars, specify ATF.
Here is what Redline recommends.
D4 ATF can be used where the manufacturer
calls for an ATF as the D4 has GL-4 gear protection
and provides the best low-temperature shiftability.

D4 ATF - synthetic ATF for use where Dexron III or
Mercon is recommended. A higher viscosity allows optimal
operation at 40°F higher temperature, providing
better torque converter efficiency. Provides wear protection
of a GL-4 gear oil. Perfect for all modern automatic
and manual transmissions which call for Dexron III or
Mercon ATFs. Superior stability allows high-temperature
operation without varnishing valves and clutches
which causes failure. Provides the far better low-temperature
operation compared to a conventional ATF.

http://www.redlineoil.com/content/files ... 20Info.pdf

Michael Westerfield · **Posted:** Thu Mar 03, 2011 11:36 pm

JamesShort wrote:

Matt, maybe you didn't see my 8th civic post. I have 12 qts of Redline MTL arriving tomorrow. When I do my konis, you should come over and let's put some good fluid in your gear box. That OE Honda shit shears and looses it's add-pack fast. I'm going to do my trans fluid yearly. I owe you 2 qts of MTL for using all your V710s up at the TnT

.

Has something changed with Honda transmissions in recent years? I don't know much about the newer 6 speeds, but the older cars really preferred gm (pennzoil) synchromesh.

JamesShort · **Posted:** Thu Mar 03, 2011 11:45 pm

MTL is functionally equivalent to Honda OE fluid (75w80). MT90 is a tad more viscous. I ran both white cap Honda MTF, RL MTL, and RL MT90 in my 98 DX civic and both RL products were superior to OE and the MT90 was too thick for 20degF mornings, but MTL was great year round.

JamesShort · **Posted:** Thu Mar 03, 2011 11:56 pm

Charlie Guthrie wrote:

OH yeah, one more thing...don't put wear inhibitors in your gear oil. The synchros work on friction and viscosity shear. I made the mistake of adding powdered graphite into a manual gearbox since it had done such wonderful wear inhibiting duty in the engine of my Sunbeam Alpine. The gearbox would not shift into any gear at any speed without grinding gears. A quick flush of the gearbox and fresh gear oil and everything was back to normal.
The same goes for molybdenum sulfide (MOLY) lubricants...they're just not for synchromesh transmissions.
The suggestion to change the tranny oil may be a very good suggestion, especially if the oil has some age on it. Viscosity modifiers can break down after a while.
Charlie G

Yep, I'm with you there Charlie. A lot of 'gear oils' have friction modifiers meant for clutch based LSD to make them lockup more gradually...this is for daily driving. Most performance drivers want the LSD to lock ASAP! But when running said gear oil in a synchronized transaxle with a helical (TBD) LSD, then no FMs are necessary to reduce friction.....you WANT friction so that the sychros, well, synchronize

. Luckily Redline makes 75w90 with FMs (regular) and without FMs (75w90 NS) for transaxles.

Karl Shultz · **Posted:** Sun Mar 06, 2011 12:33 pm

Amsoil Synchromesh has been fantastic in the S2000, and I've used Redline with excellent results. I also change the car's transmission fluid at intervals that would cause James to develop a facial tick. :lol:

JamesShort · **Posted:** Sun Mar 06, 2011 6:50 pm

Karl Shultz wrote:

Amsoil Synchromesh has been fantastic in the S2000, and I've used Redline with excellent results. I also change the car's transmission fluid at intervals that would cause James to develop a facial tick. :lol:

Nah, I changed the tranny fluid in the WRX 3 times in 15k miles but I guess given it was a Subaru 5MT, that's a different story than yours

.

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Clutch throw adjustment question

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