LS1 Conversion Clutch Won't Disengage (1 Viewer)

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Hello, I am in the process of mating a 1999 LS1 to a factory 3 speed transmission. (yes, dumb) The FJ previously had an older SBC and the clutch worked well enough. I have gathered new parts, but now cant seem to get the clutch to operate correctly. Heres my setup:

Engine 1999 LS1
Transmission 3 Speed
Factory T-Case
SACHS K70318-01 Clutch Kit
SACHS NFW1050 Flywheel
Lakewood Bellhousing/Clutch Fork (from old SBC setup)
Throwout Bearing (was in good condition operational with old setup, unknown part number)
JT Outfitters Clutch Master/Slave kit (new)

When the throw out bearing is properly spaced from the clutch forks, the slave doesn't have enough distance to disengage the clutch. Anybody have experience with this clutch kit? Does it require more throw then the slave setup can give? Would the newer clutch require a larger diameter throw out bearing, or is there a standard size for chevy applications? If I overextend the slave rod to where it is contacting the fingers on the pressure plate, then push the pedal, it will disengage enough to where i can rotate the rear output on the T-Case by hand (no driveshaft). I had hoped since the bell-housing, clutch fork, and tbearing had all been working on the older engine setup that they would swap over with no problems.

Any thoughts on clutch setups with LS conversions using original Toyota transmissions? How could I get more movement on the slave? The pedal does go all the way to, and contact, the floor. Should it?
 

scrapdaddy

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Years ago (1978) I put a 327 in my 76 FJ40 and had to make a longer slave push rod in order to disengage the clutch, if I remember right.
 
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Thanks for the reply.
The only way I can get the clutch to disengage is by making the slave push rod "too long" as in so the throwout bearing always touching the pressure plate. The rod that comes with the JTO kit is adjustable. I did see that most all GM throwout bearings are the same diameter on the mating surface. I think my issue is that the SACHS K70318-01 is a 12" clutch that requires extra force to engage. I have not modified the length of the master push rod at the pedal, but as stated above the pedal hits the floor pan before the master maxes out.

Would running a universal Wilwood 260-6766 clutch master cylinder with a 1" bore give me more travel with the JTO late model slave cylinder? I've searched everywhere but can't find a definitive answer on how to get more throw from the slave.
 
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When I upgraded by transmission from factory 3 spd to NV4500 5 spd I knew I needed to up the bore of the clutch master as I was going to an internal slave. This is the part I chose:

DSC00578.JPG


It is actually a Toyota brake master cylinder (sorry I don't remember from what year) but has a 1" bore and was brand new and not a rebuilt. Now the reason I posted this picture is because it has a different front end. I was expecting one that looked like their image where the bolt on the front would allow the internals to come out the front but instead got this version. It works fine just looks different and wanted you to be aware. It gave me the extra volume I needed to get the necessary travel out of the slave.
 
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Nice! I've read multiple threads explaining how the older FJ brake master is too difficult to operate. Apparently the pedal is too stiff to be practical? Have you been running this setup? What slave are you using with the NV4500?
 
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I know nothing about a Sach clutch, but here's what I do know:
1. The stock Toyota hydraulics only produces about .420" of travel at the throw out bearing (slave cylinder travel lost due to shift fork pivot point leveraging).
2. A stock Chevy clutch takes about .500" of travel to disengage.
3. The popular LUK that many on Mud use only takes .400" of travel to disengage, but that's right out at the ragged edge of not working.
4. The "Chevota" clutch that I build (Downey Off Road Mfg. Clutch) only takes .375" of travel to disengage.

Soooooo, don't know if this is your problem, but something to think about- - -just saying.
 
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I was able to find a 99-00 Camero flywheel, older style truck clutch disc and pressure plate and it’s all supposed to bolt together. I’ll let you know when I try.

You have the long snout crank too?
 
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Nice! I've read multiple threads explaining how the older FJ brake master is too difficult to operate. Apparently the pedal is too stiff to be practical? Have you been running this setup? What slave are you using with the NV4500?

Stiff is a relative term. What is stiff for one person may not be stiff for another. However, the 1" cylinder moves more volume and yes it requires a bit more pressure. Other things that relate to added pressure is your pressure plate. When I first assembled my SBC conversion with 33" tires my clutch could not hold the HP from the engine and the traction of the tires. I switched from a pressure plate with about 1,400 ft. lbs. of pressure to a McCleod Workhorse unit that was double sprung to 2,800 ft. lbs. which did the trick for me. I still had the original clutch master and slave and YES this was a STIFF clutch. However, it would hold and I could spin the tires on dry pavement if I desired. My desire was not to do this on the street but have the ability in off road situations if necessary and not have the clutch go up in smoke.

So when I moved to the 5 spd transmission I simply had the McCleod clutch rebuilt. The original clutch master was marginal with the original slave which was being replaced with a RAM internal which needed more volume to move the throwout bear enough. That is when I found the 1" bore single reservoir brake master cylinder with the same mounting pattern as my clutch master. For me it was the logical choice because if kept the factory look and no adapters were needed.

DSC00754.JPG


No fancy pucks for the disc. The slave floats on the output shaft collar but is kept from rotating by a pin. You can just see the pin locater opposite the hydraulic lines. The covering on the lines are actually a heat shield. I also went with an internal slave because my original setup had an issue with boiling the fluid in the lines and I had to go to silicon fluid to keep air from forming in the lines and disabling the clutch.


DSC00755.JPG


As you can see this is also a 3 finger pressure plate instead of a diaphragm which also tends to feel heavier.


DSC00756.JPG


I've run this setup since late 2014 without any issues. Other than the boiling fluid issue which was solved with a fluid change I ran the old setup since the original conversion back in the mid '80's.
 
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Now we're getting somewhere. In reference to to Downey's response, I chose the Sachs Kit because of the other issues with alignment on a GenIII 5.7L. It was my understanding that modifications would have to be made to the flywheel/pins/etc... After reading post after post I found this thread, which is why I ordered these specific components. I reached out to the user who posted the part numbers to see what hydraulics he was running, but I haven't heard back.

I have looked at several internal slave options, but wasn't sure of the exact diameter of the bearing collar output on the 3 speed. I'm assuming its the same as most GM applications? An NV4500 swap is in my future, I just want to be able to at least drive the FJ this summer with the parts I have. This rig is far from factory, and the look means nothing. If I need a master out of a 2004 Chevrolet truck, then so be it. There's just less information out there on people running GenIII setups. Other than the older FJ brake masters, do I have anymore options that have been successfully used on an FJ?

The JTO kit came with the fancy braided SS line, I read that the threads on the older brake master weren't the same as the stock clutch master? Do you have a part number on the adapter I would need to use the SS line that I have?
 
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Sorry, no help with an adapter part number. I apparently didn't save or document that part of my conversion.

What you need to know is the thread size and pitch on the master cylinder and the thread size and pitch on the braided line. Using this info you will be able to find an adapter.
 
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Byron I read through your original post. I believe the FJ55 brake master has the proper threads I would need without an adapter. If you had it to do over again would you get the FJ40 brake master instead? I also noticed today that the slave linkage I am using is aimed towards the drivers side frame-rail. I know some forks have multiple "holes" so i believe that moving the rod contact point closer to the bell housing will help with the external slave leverage. I will remove the acorn nut and drill a hole further in on the fork.

I guess my best first step is to try the early brake master since I don't want to hack up my purdy firewall paint. Surely the Sachs kit doesn't require more movement than the GM original, and this will be sufficient.

IMG_9633.jpg


Full_Size_Render.jpg
 
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I wouldn't change any of the decisions I've made to this point.

With regard to your clutch fork and linkage don't drill a hole in your fork, purchase the correct fork. My old fork was one of these.

1960-72-gm-chevy-truck-10-30-series-blazer-clutch-fork-gm-3765372_282547509352.jpg


The part number is 376372 and they were used in '60 to '72 Chevy trucks and Blazers. As you can see it already has a second pivot point closer to the bellhousing. You can buy the "V" shaped pivot or do what I did and make your own. I took a scrap piece of aluminum and drilled a hole for the rod. I then cut tapers on the contact side to fit the groove. A washer and additional jam nut kept things adjusted.

DSC00399.JPG


Be aware there is supposed to be a spring in the pocket where the ball inside the bellhousing fits. It keeps the fork attached to the ball when not under tension like during assembly.

clutch-jpg.1385345
 
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Thanks for the response. I think I'm going to order this AISIN unit off ebay ($69 free ship) and see how it goes. It looks like the pedal rod connector will be easier than the Raybestos, and my line will thread in without an adapter. The reason I may have to drill out/notch my fork is because its an old Lakewood Racing scattershield bellhousing and the mount point of the pivot is different from the factory GM units I believe. Thanks for the pictures and helpful information. Hopefully I can pull the residual valve out of this master.

s-l1600.jpg
 
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John0089, you are correct on your post #9 above, I had forgotten (out of daily practice) that to use the Downey Chevota clutch on an LS engine you also needed our custom Flywheel #460535 with the dual bolt pattern, and you needed an AA #716155 1.707" pilot bushing adapter.
 
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So the part arrived and was not blue! WooHoo! It is noticeably larger than my 3/4" AISIN master. I disassembled it to remove a residual pressure valve and I don't see one? Do I need to modify this brake master at all to work with my clutch slave?
IMG_9703.jpg

IMG_9708.jpg
 
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So I think I figured it out. Here's a picture of the FJ55 brake master installed. Looks great, and was easy to adjust. The M10 threads on the end let me keep my SS line. The early FJ40 brake master has a M9 fitting. I noticed a little cup at the end of the cylinder once I had it apart and removed a couple pieces. I believe this is the residual valve system, once removed the pedal was easier to operate and the slave has enough movement to disengage my Sachs clutch! Super Happy!
IMG_9709.jpg
 

scrapdaddy

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So I'm understanding this correct, those pieces came out of the inside. They weren't in the end where the line screws in?
 
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On the AISIN BMT112 those parts were at the end where the brake line screws in. I did not see them at first inspection, but I had to use a wooden tool to pry them out from the inside. On the early FJ40 brake master I think you can unscrew the fitting side to get to everything.

The little holes on that end cap combined with a rubber flap were the only things that I saw that would restrict movement of the fluid in the system. With the restrictor removed, the pedal moved more freely and I nearly doubled my throw from the slave. I had to cut some of the pedal rod back and adjust to prevent the slave from overextending.
 
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I tried to post pictures to help anyone else out. I know this topic has been covered before, but old posts had conflicting information. From my understanding all drum brake systems have some sort of residual valve to maintain constant pressure. This just isn't necessary for the clutch operation.
 

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