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Discussion Starter · #1 ·
I'm getting parts together for a NV 4500 swap (no I'm not made of money I'm using the credit card then figuring how to pay for it) and I have the option of using either the Jeep mechanical linkage or a new hydrolic setup. I like the mechanical linkage and the problems that I have had I've been able to fix on the trail in minutes so why would I want to put a hydrolic linkage in? I figure it would be more difficult to install, but most, if not all, new manuals are using hydrolic so is it worth it? Any insight or smart remarks are welcome. Thanks.

Tim Springer
1980 CJ7
WALSTIB/wwwthreads_images/icons/wink.gif
 
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Discussion Starter · #2 ·
I have an heavy duty clutch in my jeep that takes a very strong leg to engage. My wife would like to drive it more but the pressure of the heavy duty clutch for driving around town is almost to much for her. I plan on changing to the hydrolic just for this reason because the leg pressure to engage the clutch will be greatly reduced and have the strong holding ability for the trails. Hope this will give you some direction or insite for your setup.

79 CJ5 258 firecracker red
 

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/wwwthreads_images/icons/tongue.gif It's a mistake for anyone to ask a clutch question during my normal waking hours/wwwthreads_images/icons/crazy.gif There is NO WAY I would use a hydraulic clutch. The only reason for doing it would be if the linkage was so complex or the clutch was so far removed as to make a manual clutch out of the question. Hydraulic clutches.....and this is ONLY my opinion, mind you....are trouble. Heat affects them...I've even seen the fluid boil in rigs which had headers...fluid leakage can put them out of comission....and master/slave cylinders need rebuilding from time to time. The notion that you can gain mechanical advantage through the hydraulic system is fantasy. Mechanical advantage is simply this: "How far does your foot move for each inch of movement of the throwout bearing." That's it! If the clutch is too stiff, you need to change the geometry so that the EFFECTIVE stroke of the pedal is longer, to give you more mechanical advantage. I have driven Full-Size GM pickups for years, and their HUGE problem is the 12" Borg & Beck clutches. You just cannot hold them down at a stoplight. After breaking EVERY piece of linkage...fulcrum pins...throwout forks....and every other darn thing, I got tired of pulling that bellhousing and finally reduced the spring tension by cutting one spring out of each of the three groups, going from 12 springs to only 9. It is STILL enough clutch to hang the truck vertical, and at least now it isn't wearing out the crank thrust surface from so much dis-engagement pressure. We used to put 12" B&B clutches behind big Chryslers that had some REAL torque and HP. Having a clutch like that on a SB 350 Chevy is really overkill, so the reduction in spring tension works just fine. We used to refer to the clutches as "Percent Beef"...that is with ALL springs in place, it was 100%...with 9 out of 12 it was 75% beef. Rarely, if ever, did we use a 100% beef clutch behind any stock engine./wwwthreads_images/icons/smile.gif

CJDave
Quadra-Trac modified by the crack moonguy/wwwthreads_images/icons/wink.gif/wwwthreads_images/icons/smile.gif/wwwthreads_images/icons/tongue.gif transfer case team.
 

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I can see using a hydraulic clutch for 2 reasons. The first is like swcobb mentioned earlier, the second is if it's already there. I have the hydraulic setup on the Scrambler, but it came stock. I have blown 3 lines, had to rebuild the master, and replace the slave. All totalled it's about $120 to throw in a hydraluic new. My lines blew due to the engine torquing and weakening the line. I solved this by putting a short flex brake line near the slave. The heat is also a problem, even with the small 4 cyl I'm running, but I solved it by sleeving the exhaust. Guess where the leaking brake fluid goes, yep, right onto the hot exhaust pipe, resulting in one fire, luckily I was carrying the recommended fire extinguisher so it wasn't a problem. I had the line go so often and in such places I actually bought a flaring kit to keep in the jeep. I had it go on top of Mt Pleasant in Maine once and even got NAPA to deliver a new line to me (OK, so he was my brother in law and liked a challenge, but it makes a good story).

I have seen the linkage on regular clutches bind and not work off camber or twisted up, but heim linkage would cure that. I have my hydrualic setup and everything is fairly new, so I'll stick with it (too lazy to convert), but if you have a choice, stick with the manual.

JEEPN
'81 CJ-8 Scrambled!
GM151/SM465/NP205 twinstick/7"Lift/33"TSL's/IHC D44's 4.10's Lock'd
 

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/wwwthreads_images/icons/tongue.gif Actually, Mark...the only way that cobb can gain is if he can set it up so that the master cylinder bore is undersized and using Bernoulli's Principle, would required that more pedal travel be used to displace the slave cylinder enough to disengage the clutch. Otherwise, as I mentioned, there IS no mechanical advantage inherent in the hydraulic clutch system. OR.....and this is REALLY crazy....cobb could use a POWER BRAKE setup to control the hydraulic clutch slave cylinder. That way his Jeepchick would have power brakes AND power clutch. LEVE is doing a frame-off right now to install a fiberglass tub, and a while back we kicked around some POWER CLUTCH ideas for his Jeep since his clutch leg is the one that does not work very well. We basically were working with the "Suspended Vacuum" type of system, actuated with a lever similar to a motorcycle brake handle that attaches to the shift lever. A totally hand-actuated, power-operated clutch/wwwthreads_images/icons/smile.gif

CJDave
Quadra-Trac modified by the crack moonguy/wwwthreads_images/icons/wink.gif/wwwthreads_images/icons/smile.gif/wwwthreads_images/icons/tongue.gif transfer case team.
 

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I thought Bernoulli's principle was that the air traveling over the top of a wing travels faster and created lift.

With regard to the clutch, I thought (sure I read this somwhere) the pedal ratio was different on a hydraulic vs mechanical clutch pedal. I'm sure I have it at home in one of my books.

As to the hand clutch, what an awesome idea! Have the clutch level mounted to the side of the shifter, so when you grabbed the stick you could engage/disengage it. Either that or set up the jeep with motorcycle handlebars /wwwthreads_images/icons/wink.gif.

JEEPN
'81 CJ-8 Scrambled!
GM151/SM465/NP205 twinstick/7"Lift/33"TSL's/IHC D44's 4.10's Lock'd
 

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/wwwthreads_images/icons/tongue.gif Drat it Mark! Now you have ME second-guessing.....actually you're right about Bernouilli developing the upthrust concept from his basic EQUATION of hydrodynamics.....not to confuse the famous Bernouilli's Equation...bedrock of hydrodynamics...with the Bernouilli Principle, which together with Pascal's Law, is the Hydraulic Jack....little piston much movement=big piston little movement. IN ANY CASE....the pedal HAS to move farther or it's useless, and since the geometry doesn't suffer from bell cranks going too far over center like they can do in a manual setup, hydraulics MAY be an advantage from a design stand point. I have noticed that some manual clutch linkage does go "over center" and get easier to hold in once it is in all the way. If you were to really bear down and sweep out all the corners, you could build the perfect manual clutch linkage. Do you understand the "suspended Vacuum" concept as applied to pwr brakes?/wwwthreads_images/icons/crazy.gif

CJDave
Quadra-Trac modified by the crack moonguy/wwwthreads_images/icons/wink.gif/wwwthreads_images/icons/smile.gif/wwwthreads_images/icons/tongue.gif transfer case team.
 
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Discussion Starter · #8 ·
Bernoulli's principle talks about airflow or hydraulics (i learned with air) through a tube being decreased in diameter thereby increasing thrust. The Army taught me that and its been awhile. All I can remember is the diagram. They talked about this on the show where the kid builds rockets. He used the principle for the rocket thrust discharge.

Can you fix it?
I got a welder and a grinder. Heck yeah I can fix it./wwwthreads_images/icons/cool.gif
 

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No, I guess I missed that part of the post, read right over it. It was there when I reread it though, but it lost me again. Can you explain a little further, sounds interesting. Gotcha on Bernoulli, I should retake a physics class or two. You know, use it or lose it. Been thinking of taking a few chemistry classes as well, just to keep up on stuff.

JEEPN
'81 CJ-8 Scrambled!
GM151/SM465/NP205 twinstick/7"Lift/33"TSL's/IHC D44's 4.10's Lock'd
 

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/wwwthreads_images/icons/blush.gif Man....I must be having a "Senior's moment" here....I just went and looked it up and you are right! And so is Mark! The hydralic jack system most closely resembles Pascal's Law....which states that "fluid pressure acts equally and on all sides", thus giving rise to the hydraulic jack theory and the resulting potential for mechanical advantage. Bernouilli's Principle is the effect that high velocity has on pressures, as in a venturi, and the kinetic energy of non-compressible fluids as changes in velocity occur mainly due to pipe diameter changes. Oh well.....looks like I need to get those books out again.(It's only been....lessee...35 YEARS! Yeek!) You know, as time goes on, you use more and more "short cuts" in figuring losses, and you sometimes forget the root theories that your short cuts were DERIVED from. Like I always use .7854 instead of PiR2 when figuring tanks and pipe volume, even though it is a derivative of that very formula/wwwthreads_images/icons/crazy.gif Glad to se SOMEBODY is paying attention/wwwthreads_images/icons/blush.gif

CJDave
Quadra-Trac modified by the crack moonguy/wwwthreads_images/icons/wink.gif/wwwthreads_images/icons/smile.gif/wwwthreads_images/icons/tongue.gif transfer case team.
 

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/wwwthreads_images/icons/tongue.gif "Suspended vacuum" is a way of speeding up vacuum assist. Because it takes time to evacuate a cavity and cause the diaphram to move, they came up with a way of applying vacuum to BOTH sides of the diaphram, then "breaking" the vacuum on one side to cause the diaphram to move, since breaking a vacuum is quick. So "suspended" vacuum is diaphram-neutral but under negative pressure, just waiting for one side to be released. That also provides for "emergency" application of vacuum trailer brakes for example when the service line is broken in an accidental breakaway. In the old days, we had to flip the trailer brake valve two blocks in advance to get the brakes to hold in time on the old vacuum semis and trailers/wwwthreads_images/icons/frown.gif On LEVE's clutch scheme, we took advantage of high manifold vacuum as you let off to shift to help release the clutch, and low accel vacuum to engage./wwwthreads_images/icons/smile.gifMan...do I ever hate Chemistry. Took about 35 units and still didn't learn it/wwwthreads_images/icons/frown.gif

CJDave
Quadra-Trac modified by the crack moonguy/wwwthreads_images/icons/wink.gif/wwwthreads_images/icons/smile.gif/wwwthreads_images/icons/tongue.gif transfer case team.
 

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Dave, you've forgotten more than I'll ever know, but I'll never stop learning.

What an awesome concept! It's those things that help someone retire when they're 30. One less idea to come up with and one more item of knowledge stored away for suture use. Of course, I'm still on the manual brakes, haven't dared enter that arena yet, but all in good time.

Chemistry is like anything else. "Let's see, mix these two, oops, smoke, OK, don't mix those two again". Of course, the trial and error mothod only gets you so far, then you get killed. It's interesting, wish I had more time to explore it further.

JEEPN
'81 CJ-8 Scrambled!
GM151/SM465/NP205 twinstick/7"Lift/33"TSL's/IHC D44's 4.10's Lock'd
 

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WOW,
I hope there wont be a quiz on this stuff later.
As far as the mechanical vs Hydraulic clutches, I know Im planning on going to mechanical when I do my next motor swap, probably in the winter,(unless my present motor knows something I dont).
I had the slave cylinder in my 89 get so hot durring a fast charge through Claw Hammer last summer, that it melted the bushings and dumped all of my hydraulic fluid. Left me with a winch and starter, 1st gear self extraction(untill the starter went). The simpler the better for me, next time. I think I will use a Landcruiser set up.

Jeff
89 Wrangler
If at first you dont succeed, your replacement will try and try again.
 
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