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Discussion Starter · #1 ·
Hello all its been a while since I've been on here, so far I'm liking the renovations that have been done. In 2018 I purchased a 4jb1 mated to a MUA5 for my 87 trooper ll. I installed the engine and trans and had my welder fab up the mounts, they are better than factory! I got the engine running and had my driveshafts resized, and.... that was it. life kicked in, I went to college 4 hrs away and hardly ever came home, and when I did I never had time to touch her. she's just been sitting at the farm waiting for a chance at life. Now years later, degree in hand I have come back home, and I have already begun the build. Here are the facts ( body and frame still in great condition, Engine once again runs, Mech oil pressure gauge shows good pressure at idle, electrical system works... kinda and the cab very surprisingly is dry.) Now I would have this scootin around the farm right now if it weren't for my clutch problem. As we know my trooper came with a mechanical clutch, the MUA5 is a hydraulic clutch, I have pedel boxes for the clutch and brake of a MUA5 trooper. I also have a master and slave cylinder. I even have the hard line with a damper on it ( after some research I believe this should be deleted?) Now if anyone has put an MUA5 into an 87 trooper or similar, I need some assistance. What's the best way to mount the pedal box? I know it will require drilling, I'm just curious how to get it lined up, I know the booster makes the space where it is supposed to mount very tight. the other option is something I have read only once, is to somehow convert the MUA5 to a cable system, although the process seemed intensive. It's good to be back in the Isuzu world and I look forward to once again engaging with yall!
 

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It is more difficult to install a cable cluch system and a cable system is not as good as a hydro system. Installing the factory pedal box is a waste of time and energy. Leave the original brake and gas peddle where they are and simply add a new clutch pedal with master cylinder. Wilwood makes a great peddle/master assembly that cost 150.00 bucks.
 

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Discussion Starter · #3 ·
Thanks for the info Shawn, what would be the link or PN for that assembly, and what would be the installation prosses?
 

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I don't have the part number memorized. Search SummiRacing website for Wilwood clutch pedal master cylinder.. many opinions will pop right up. Choose the one you like.

Install is nothing more than test fit & cuting a hole. Then bolt in place, connect hydraulic hose and bleed air from system. Nothing special about it.
 

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Discussion Starter · #5 ·
Ok, I found a few, could someone explain the benefit of this vs the petal and master cylinder I have on hand?
 

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Discussion Starter · #6 ·
Anybody else got recommendations? I really don’t have an extra $150 to spend on something I basically already have.
 

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'88-'91 Troopers have power disc brakes and a hydraulic clutch master cylinder mounted right there on the firewall.

I woudln't be surprised that the bolt pattern of the pedal box isn't all too much different than the one for a MUA5 trans with hyd clutch.

There's no difference in the size of the engine compt of an '87 Trooper than there is in the compts of a '88-'91. So things are gonna fit, even if they're tight.

Do you have any yards near you, where you could take a picture of a later-model Gen I to see how it looks?

If all the brake and clutch parts are removed, you could even make a template of the firewall. This might help you in transferring bolt holes.

Look at it this way, to do anything you've got to remove the existing pedal box. Once removed, compare the 2 pedal boxes side-by-side. You'll get a good sense if there's anything radically different.

You may even have a few bolt holes that line up. That'll help immensely with the mod. Bolt up the MUA5 pedal box and see what it looks like.

Anyway, that's pretty much how I'd go about it. You've got to pull what you're changing, compare to the new parts, check the fit, do what you need to do to make it work.

IDK how the (2) studs for the hydraulic clutch are attached to the firewall; they may be spot-welded, pressed-thru, etc.
Once you've mounted the MUA5 box in its new home, unscrew the "yoke" off the end of the clutch master cylinder's pushrod. That yoke fastens to the clutch pedal with a pin. Temporarily mount the yoke on the pedal (in its normal position, with a bolt that's about as long as the clutch cyl push rod you just removed the yoke from.

You can position the clutch pedal yoke and temporary bolt, and use the bolt as a guide to mark a center-hole thru the firewall. Very carefully lay that hole out, measure as you need to. Then drill a hole and see how the bolt aligns into the engine compartment. If you just drill a small hole for the bolt, you'll have room to adjust the center of the hole once you make sure the bolt lines-up well going thru the firewall & into the engine compt.

You might have to file or grind the hole out one way or another to get it lined up so it's going to hit the plunger on the clutch master cylinder, straight-on. That's the critical thing.

Once you have the center of that hole perfectly positioned, enlarge by grinding until the larger-diameter part of the master cylinder will fit thru the hole.

Then, with the clutch master cylinder strait up-and-down, you can use the holes in the mounting flange to lay out the mounting holes in the firewall.

After that, all you need to do is figure out how to bolt it to the firewall! One way that would be pretty easy is to use a "Star" washer between the bolt head and the firewall. Insert that bolt thru the firewall, from the inside. When you tighten the mounting nuts on the engine compt side of the clutch cyl, the star washers will "bite" into the bolt head and the firewall sheet metal, keeping the bolt head from turning. Then you don't even have to have a wrench on the inside.

Ideally you could tack weld the bolt heads to the firewall. That's pretty handy only if you have a welder, and it's pretty tight in there so you risk damaging other components when welding.

Or, maybe the clutch pedal pushrod will line up with the old clutch cable hole. I wouldn't be surprised if it did. And the Power brake booster may fit the spot occupied by the old one.

Anyway, that's more-or-less what I'd do. It's a process of discovery, you dig into it, then lay the new part in where the old part was, and see what it's gonna take to get it in there. It helps to have an eye for that stuff, but that comes with experience.

Once you get the old pedal box out, stick 'em side-by-side and take a pic. Post a few different shots here and we can all scratch our heads together about "What Next".

Hope that helps, you just gotta dig in there!.............ed






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Discussion Starter · #8 ·
Ed, I really appreciate the write up, very informative, I’ll dig into it sometime this week. Good call about the template, unfortunately I haven’t seen any troopers in Yards for a while, besides the one I bought 😂. If anyone reading this has an 88-91 trooper with all that taken off, I’d really appreciate a template.
 

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Do these help? From an 89 - 91 Trooper. I removed the clutch assy to use on an auto to manual conversion I was working on. Looks like there may be a reinforcement plate? Not sure how it compares with a cable clutch firewall.

Mike



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Discussion Starter · #10 ·
Gruff, I appreciate your reply, these pics shed a light on what I'm going to need to do. I appreciate you taking the time to grab them. I'm not sure what your affiliation with this trooper is, but would it be at all possible for you to remove the booster and mock me up a template? I would of course pay you for your effort as well as cover the mailing.
Garrett
 

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Should not be a problem as long as you're not in a big rush. This time of year is one of my busiest times, not much free time. And I'm trying to get my Trooper back on the road, too. It's been down way too long.:( I may be able to chip away at it a little here and there, let me see what I can do. Basically what you need is the location of the clutch mounting holes in relation to the brake mounting holes? From the engine bay side? (Much easier access from the engine bay)

Mike
 

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Discussion Starter · #12 ·
That’s exactly what I need Gruff, the engine bay is where my space is the tightest, so that would be perfect! I can wait a little, I got other things I can work on. Let me know about when you can get it and how much I would owe you.
 

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Discussion Starter · #13 ·
Also the location of the booster and master cylinder holes would be awesome as well.
 

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Looked at it this morning. Master cylinder already off, so just have to pull the booster. Think I can get by with leaving the brake pedal assy in place. I had planned on a sketch showing the layout of both the brake and clutch holes. Maybe try to place a piece of paper/cardboard against the firewall and marking the holes from the inside. Won't know til I get in there. As far as when, I'll do my best to get it as soon as I can, just don't know when that will be. As far as how much? Well, I've got a buddy that says "if you have to ask, then you can't afford it". :LOL: Unless it's a lot more trouble than I think, we'll consider it my contribution to the forum for all the knowledge and help I've rec'd here.

Mike
 

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Discussion Starter · #15 ·
Cardboard would be awesome, and at least let me cover mailing.
 

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OK, Dirt. I had a chance to work on this. Here's a pic and a sketch w/dimensions. Hope it makes sense. If not, ask. I don't think tracing it to a piece of paper or cardboard is gonna be accurate enough. There's an offset in the firewall that will make it hard to mark, so I measured as best as I could. I used the underside of the pinchweld as a vertical reference point for both. The distance separating them side to side is hard to measure because of the offset, but I think I'm pretty close. Even if you were off an 1/8" either way, I don't think it would make a big difference. I did compare it to an '87 with a cable clutch. Hard to tell exactly as the '87 was still intact, but I'd bet good money that both the hydraulic and cable clutches are on the same vertical axis. I'm guessing the hydraulic center is about 1 3/4" lower than the cable center. You can confirm the 5 clutch holes in relation to each other by measuring the hydraulic clutch bracket while it's in your hand. The large center hole is centered between the two outboard clutch mounting holes. After looking at both Troopers, I don't think you'll have a problem fitting the clutch master cylinder in that space. I've read that the firewall is a weak link with the cable clutches, in that it will develop cracks. Maybe Isuzu addressed that on the hydraulic clutch models by adding a reinforcement plate? So it may be wise to beef up the firewall with an additional stiffener plate between the clutch pedal assy and the firewall similar to the fix for a cable clutch firewall. Then, the hydraulic clutch may not stress the firewall like a cable clutch, but they put that stiffener in there for a reason. Let me know if you need any more info. Oh, and a suggestion. Don't know if it's possible to change the title of this, but something like "Converting cable to hyd clutch" would make it easier to find for those using the search function in the future. Again, just a suggestion. Good luck!!

Mike

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Discussion Starter · #18 ·
Thanks, gruff, sorry I didn't message sooner, I have had my hands full with other problems. The pinion on my daily went out.🤦‍♂️ I really enjoy a limited run factory modded offroad truck until you can't get a used diff because they are different from the other models.🙄 But I can't thank you enough, I hope to jump back in soon. As for the title, yeahhhh I made it in the heat of frustration, thought it would catch someone's eye😂. I wish I could change it, but I don't know how. if anyone can enlighten me, I would be very appresiative.
 
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