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Early AMX / Javelin Hydraulic Clutch Setup |
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shootist
AMC Addicted Joined: May/24/2012 Location: Triad, NC Status: Offline Points: 1023 |
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That circuit is low current. I did happen to measure the load before connecting because the original neutral safety switch has pretty beefy contacts (small wires still) but could have likely drawn 5-15 amps pretty easy. I never saw more than 1-3 amps of draw and most of the times well below 2 amps. Peak hold showed the spikes up to 3 amps for the first instant of relay engagement and sustained draws during the cranking cycle of 1.5-2 amps. I did notice that the longer you held the key in the start position the amps would creep upward slightly but it was always negligible and the highest creep I saw was after about 15 seconds of holding the key turned in the start position. All this said, I don't believe we have anything to be concerned with in our setups. Now if you look at the GM starters that have the bendix driven by the start signal I bet they could pull higher loads.
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304-dude
AMC Addicted Joined: Sep/29/2008 Location: Central Illinoi Status: Offline Points: 9082 |
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Hey guys... I am looking into a clutch master cylinder for my odd setup. I like the option to use a name brand universal kit offered by speed shops. But like most of my build I am doing over the counter parts. Want to have at least a 7/8" bore and 1" to 1.5" stroke.
Unfortunately there are few 7/8" units that are not plastic or require some odd bracketry to lock ring into place. Since I am not able to find stroke info, as I am interested in the 82 Grand Wagoneer unit, but leaning on the GM Yukon as it has remote reservoir already setup to use the brake's MC reservoir's shared fitting. Makes an easy and clean service. Is there some site that gives more details other than fitment that you maybe aware of? Thanks! |
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71 Javelin SST body
390 69 crank, 70 block & heads NASCAR SB2 rods & pistons 78 Jeep TH400 w/ 2.76 Low 50/50 Ford-AMC Suspension 79 F150 rear & 8.8 axles Ford Racing 3.25 gears & 9" /w Detroit locker |
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shootist
AMC Addicted Joined: May/24/2012 Location: Triad, NC Status: Offline Points: 1023 |
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Wilwood's site has bore and stroke listed for each of their units. The closest that I see to your spec is the Part No. 260-15092 which has a 1.25" stroke with a 13/16" bore. It is the GS Compact Remote Master Cylinder. You can mount a remote reservoir so angle of the dangle will make no difference. It is pretty much the unit that I am using aside from the bore size being different for mine.
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shootist
AMC Addicted Joined: May/24/2012 Location: Triad, NC Status: Offline Points: 1023 |
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www.wilwood.com/Pdf/Catalogs/TechCatalog.pdf go to page 65 of the adobe document page 61 of the catalog. They have one which is.813" bore and 1.4" stroke part no 260-11972 but you also would need to order a reservoir kit.
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304-dude
AMC Addicted Joined: Sep/29/2008 Location: Central Illinoi Status: Offline Points: 9082 |
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Thanks... After a bit of searching, of all things, pre 96 Corseca V6 has a nice 7/8" bore and long shaft, plus remote reservoir on the setup. May pluck one from our local salvage yard, If I am so lucky. Mid range manual cars are rare here. If it don't pan out your find may be an option, but I think I will need the extra volume for actuating large caliper rear disc brakes, since the e-brake is not an option with my custom rotor and caliper combo. |
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71 Javelin SST body
390 69 crank, 70 block & heads NASCAR SB2 rods & pistons 78 Jeep TH400 w/ 2.76 Low 50/50 Ford-AMC Suspension 79 F150 rear & 8.8 axles Ford Racing 3.25 gears & 9" /w Detroit locker |
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Greyhounds_AMX
AMC Addicted Joined: Nov/14/2009 Location: Kansas City Status: Offline Points: 1268 |
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Well for those of you still following, here's the thrilling conclusion. Everything is installed and working, shifting great, and no leaks. During my "Header Hack" episode I realized that to have enough room to snug the headers up under the car where I wanted it there would be no room for the stock Jeep type slave that I was planning to use. So I used a "pull-type" slave instead. These are used a lot in stockcars and kit Cobras for the same reason, they want low ground clearance and need to get the headers up where the slave would normally mount. In order to stick with the Jeep slave bore diameter and have enough travel based on my calculations, the only slave that would work was the Wilwood. They only offer one pull-type slave, so thankfully it was in the right bore size (7/8"). I had to make up a mounting bracket to hold the fixed end of
the slave, and that grabs on to two of the T5 tailhousing bolts and also bolts
through a tab that was on the side of the T5. Since it was all pretty close to
the header still, I worked up a heat shield that straps on to the slave
cylinder. |
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1968 AMX 390 w/T5
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Greyhounds_AMX
AMC Addicted Joined: Nov/14/2009 Location: Kansas City Status: Offline Points: 1268 |
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The only problem I had was with the surface finish of the piston rod in the Wilwood slave cylinder. That rod slides through a critical o-ring seal, if that goes you lose fluid and lose the clutch. But the slave I received had the rod in an "as-turned" finish, which was basically like running a fine file back and forth across the o-ring. Here's what it looked like under magnification, just for fun: Wilwood sent me another at reduced cost (as mine was out of
warranty), and it had the same issue although manufactured over a year later,
so I sent that one back to them and polished the shaft on the one that I had.
It's easy to do - once disassembled you can chuck it up in a drill press and
use varying grades of wet sandpaper to smooth it out, 600-1500-3000 etc. After
that the rod was mirror smooth. |
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1968 AMX 390 w/T5
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shootist
AMC Addicted Joined: May/24/2012 Location: Triad, NC Status: Offline Points: 1023 |
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Holy quality control Batman! That should never be an issue with a supposed quality name brand. Thanks for sharing I will be sure to pay closer attention.
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304-dude
AMC Addicted Joined: Sep/29/2008 Location: Central Illinoi Status: Offline Points: 9082 |
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Here i thought you had that all completed... i guess it was until you did the final of the header install.
And yes, that machined finish is no good on a rod! You want them smooth as silk for the best seal life. Though being that low and facing forward, you may look into making a shield or boot to cover the open pin eye. Dirt and debris may knock up into the mechinism and gum up the works. Though i am only looking at it from the photo point of view. Your keen enough to know what to look for, Edited by 304-dude - Feb/14/2019 at 2:39pm |
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71 Javelin SST body
390 69 crank, 70 block & heads NASCAR SB2 rods & pistons 78 Jeep TH400 w/ 2.76 Low 50/50 Ford-AMC Suspension 79 F150 rear & 8.8 axles Ford Racing 3.25 gears & 9" /w Detroit locker |
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Greyhounds_AMX
AMC Addicted Joined: Nov/14/2009 Location: Kansas City Status: Offline Points: 1268 |
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When I spoke to Wilwood they had no idea that the rod
surface finish was an issue at all, or maybe in their opinion it isn't an
issue. It's apparent that they used to hone/polish them, as I found pics online
from a Cobra kit car site where a guy took his apart and you can see that the
entire length of the larger OD section of the rod that contacts the o-ring had
a polished finish when compared to the smaller diameter portion. So either their current supplier is skipping steps and Wilwood isn't catching it in their QA process, or Wilwood purposely stopped finishing the rods in an effort to cut costs. Another issue is that the inside of the housing is anodized
black just like the outside, and anodizing breaks down in break fluid, so it's
constantly leaching black particles into the fluid. I thought it was the o-ring
breaking down at first, but after researching I found that anodizing simply
doesn't hold up against brake fluid. I'm not sure if the result is abrasive,
but it's certainly worse than clean clear fluid. While the slave was apart I
should have taken the time to soak the inside with brake fluid and let it site
for a while then scrub it out a bit and give it a fine sanding as well, maybe
with a brake hone. Bygones. One other aspect of these that's pretty sad is the complete
lack of a guide bushing for the rod where it passes through the housing. All
that's there to support the rod is the o-ring, so any minor side loads will eat
the o-ring up and then it leaks and strands you. Again. But before everyone decides that the Wilwood unit is the Devil's own work let me point out that it's the only pull slave with machined pockets in both the piston and the housing to help minimize the pedal force. When you apply the clutch the slave has to compress a small trapped volume of air on the side of the piston opposite of the fluid side. The amount of force required to compress that air is dependent on the original trapped volume versus the displaced volume, and by adding the two pockets they've increased the initial volume. The end result is that is only takes about 17 lbs of additional effort instead of 25 lbs, as you would have from the Speedway, Howe, CNC, or Coleman units. It also has longer travel than all of the other units. It amazes me though that they put that much effort into the design and then pooch up the finish machining. If Wilwood was to make a "Super Duty" version of this thing from stainless with a chrome plated rod, a bushing in the end to support the rod, a real u-shaped seal (or two) on the piston, etc. they would corner the market. I know lots of guys who have had internal hydraulic throwout bearings fail, and many would happily run an external pull slave instead if it was really high quality. That way if it ever did start to leak they'd have easy access to it. I even pitched this to the Wilwood guy I was dealing with, but it was pretty obvious that this was just another job for him. |
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1968 AMX 390 w/T5
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