upgrading your square with a hydraulic clutch

[GreaseDog]

i've had several guys ask me about swapping a hydro clutch into an automatic truck, or a truck with a factory mechanical clutch. so i thought that this post could be useful in the future.

for starters, you need the proper 85-87 hydraulic belhousing. the hydraulic belhousing from an IFS truck may work, but the slave cylinder is on the wrong side. you'll also need the specific hydraulic clutch pedal assembly, and the support rods that go between the pedal pivot and the firewall. everything else is available, as they're wear parts. some parts may be tougher to find, but they are available. i've heard of guys having problems finding a hydraulic line to go between the master and the slave. IIRC they are available from Napa.

the studs on the end of the supports are used to mount the master cylinder. proper positioning of these support rods, and the master cylinder are critical to proper geometry and operation of the clutch. fortunately the wiper motors are positioned the same on all trucks in the same position away from the brake pedal, so you can use the bolts for the wiper motor as a refrence point to accurately drill the proper holes.

here are the measurements to locate the master cylinder and the support rods.

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on trucks 84 and newer, you will often find dimples in the firewall where the center of these holes will be, if you find them, you can just use them and drill the holes to the proper size and be done with it.

the measurements are courtesy of TJ (aka big83chevy4x4)

See Post #22 for further template info: http://www.gmsquarebody.com/forum/showpost.php?p=230533&postcount=22

 

[MrMarty51]

I do not understand why anyone would want to convert from a mechanical clutch linkage to a hydraylic clutch.
From working on so many pickups and cars with the hydraulic clutch system and all the problems they bring,I just would never think about doing such a troublesome downgrade to one of My pickups.
Sometimes these hydraulic systems wont allow the throw out bearing to fully release,thus causing premature failure of the T.O. bearing.

 

[MrMarty51]

OK,I reead the other thread,about headers and such,so,I do now unnerstand the reason for wanting to go wit the hydraulic system.
Keep them master cylinders in "REAL GOOD CONDITION" as You will not notice them leaking all over the carpet until they quit working,then it is too late and the carpets`ll be all soaked with braking fluid.
Whenever I am completely rebuilding a haydraulic system,rather it be brakes or clutch,I ALWAYS go into them with DOT-5 fluid.it is not as messy as DOT3 and it does`nt eat paint.
ALWAYS, when switching to the DOT-5, put a statement to that affect where it is very visible,next to the hydraulic systems,just as a reminder to that affect.
Let us not start a big debate over Your preferences of using the 3 or 5 fluids,If someone wants to bring in that debate then fire up a new thread in the brakes section of the forum.

 

[HotRodPC]

I do not understand why anyone would want to convert from a mechanical clutch linkage to a hydraylic clutch.
From working on so many pickups and cars with the hydraulic clutch system and all the problems they bring,I just would never think about doing such a troublesome downgrade to one of My pickups.
Sometimes these hydraulic systems wont allow the throw out bearing to fully release,thus causing premature failure of the T.O. bearing.

I'm like you and think the same way, and wanted to go Z bar manual linkage with my 85 and I probably would if it were a 2wd, but on 4wd it does make sense to go hydraulic. Consider Frame twist when wheeling, what's going to happen with your Z bar linkage as this happens? Also consider lift body lift kits if you're going to use them and lengthening rods etc. Hydro clutch and a flexible line avoids all those issues.

When I do mine, depending on the fittings, I'm hoping to have a braided line made with a bit of extra line

 

[GreaseDog]

No mechanical linkage to wear out... Z bar parts are stupid expensive to buy. I'll see if I can remember to get some pics of my clutch linkage in my 80. Every single piece is shot.

With the hydraulic setup, all of those exterior moving parts are eliminated. No greasy connections to attract dirt and grind away at them. No linkage to jam. No return spring to rust away.

If you look at the layout of the system, soaking your carpet with clutch fluid is almost impossible, as the matter cylinder angles downward. If it were to fail, must of it would drip off the end of the natter cylinder outside the cab.

And then there are those of us who like to use or trucks on something other than a perfectly flat, level surface... With the frame flexing independent to the body flex, and rubber mounts between the two, jamming up that complex linkage becomes a huge issue. Hydraulic hose doesn't even flinch.

 

[Jake_S]

I'd rather have a hydraulic clutch set up over a mechanical. Less moving parts to fail when you're in the middle of nowhere.

Jake

 

[HotRodPC]

I won't buy that theory on clutch linkage. I can macgyver clutch linkage to work, but once a slave or master loses a seal, piston, cup or hose, your jacked and there is no fixing that to get home. But then again, I don't need a clutch pedal to get home. Done it several times. A couple in my own vehicles, and many times for others who don't know how to do it.

 

[GreaseDog]

Power shifting? Or just one gear?

 

[HotRodPC]

Power shifting? Or just one gear?

Not sure what you mean, just one gear, but certainly not power shifting. I call it float shifting. Go thru the gears both up shifting and down shifting without using the clutch pedal just by self synchronizing the transmission with the engine rpm and know when to shift with the timing of letting off the gas pedal.

You only need a clutch pedal to take off and to come to a stop. There's ways around that too, just hope you have a good battery and a good starter.

 

[Driver4r]

Not sure what you mean, just one gear, but certainly not power shifting. I call it float shifting. Go thru the gears both up shifting and down shifting without using the clutch pedal just by self synchronizing the transmission with the engine rpm and know when to shift with the timing of letting off the gas pedal.

You only need a clutch pedal to take off and to come to a stop. There's ways around that too, just hope you have a good battery and a good starter.

Its called Rev-Matching.

 

[HotRodPC]

Its called Rev-Matching.

Really? Been doing it for over 28 years and never heard it called that. But then again, I never did graduate high school. Think I'll stick to "float shifting" so everyone around here knows what I'm talking about.

I know I've seen 2 guys who tore up transmissions thinking they could do it. One of them being 3rd gear in the C6500 after I started driving the Pete.

 

[HotRodPC]

The diagram is a great addition. Anyone who currently has a Hydro manual truck and takes off their Clutch Master for repair or swap, please gets pics with and without the Clutch Master in place and post pics to this thread. They'll be great to have for a visual to compare to.

 

[GreaseDog]

Better yet, anybody with an 84+ truck, preferably automatic, who can locate the factory dimples and get pics of them.

 

[HotRodPC]

Better yet, anybody with an 84+ truck, preferably automatic, who can locate the factory dimples and get pics of them.

hmmm I only 5 of those, 84, 85's & 86 that are all auto's. I'll have to check them out. In fact going to look at my pics now.

 

[GreaseDog]

They might be kinda hard to see off you're not focusing on them, and I have seen them with the factory seam sealer over them, making them completely undetectable.