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July 2013 Your Jeep - Tech Questions

Posted in How To on July 1, 2013
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Reading My Mind
I have an ’88 Wrangler with a 4.2L. I’m going to be swapping to a Motorcraft 2100 series carb. I am wondering your guys take on the Davis Unified Ignition Distributor (DUI) by Performance Distributors. Yay or nay? And will my stock cam gear get eaten by it? My Jeep has 52,000 original miles on it. Thanks for your help!
Doug Wickenheisser

It’s like you read my mind. I just swapped a Motorcraft 2100 on to my ’88 YJ’s 258ci (see “3K 3-Day YJ” in this issue) with help from Summit Racing. It was a great swap once I got an intake manifold that was not damaged and subsequently customized with epoxy. I also swapped in a Davis Unified Ignition distributor and Live Wire spark plug wires from Quadratec (“Number Two, Part 2,” June, ’13). So far I love both of these additions to my YJ and would recommend them to anyone with a 258ci-powered Jeep. The 2100 idles great off-road and the firepower that the DUI adds is awesome. So far I have had no problems with the DUI distributor eating cam gears, nor have I heard about this with 4.2Ls. Usually when a distributor damages a cam shafts’ gears or vice versa it is because the on one of these parts is harder than the gear on the other. I am certain DUI would not do this and would build their distributors with the correct drive gear that is of similar hardness to the cam gear.

Yep, Not a Good Idea
I have an ’85 CJ-7, with a small-block Chevy, TH400 tranny, Dana 300 case, 35-inch tires, stock axles, except for rear one-piece axles. I know the front and rear are not that strong. I don’t really want to spend thousands of dollars replacing them, but I do want lockers and deeper gearing. Since I don’t do any rockcrawling with the Jeep do you think I can get away with running lockers? I only occasionally hit the back roads and some mud. I’d like to get into rockcrawling it, but I just don’t have the cash to do so. I’m a family man with kids to feed. Any suggestions? If I had the cash to go hog wild, it would be a beast.

It sounds like you already know what we are gonna say. Especially with a small-block Chevy V-8 adding lockers is just gonna make it more likely that you will break an axle shaft or U-joint. You could re-gear both axles, add lockers front and rear and add chromoly axles with larger chromoly U-joints to your front Dana 30. You might be okay as long as you baby it if you get into rocks or areas where you have good traction, but you are gonna spend money buying parts and working on your stock axles that could go towards better/stronger axles. Of course you could build up your current axles and then sell them when you have saved up enough for bigger axles. You probably won’t have a hard time selling them if they are re-geared and are built with good components. The problem is that with lockers and 35s you are not gonna get to really use the power of the V-8 without worrying that you are gonna break something. Of course even without lockers a V-8, 35-inch tires, and a heavy right foot may break parts. I’d aim for 1-ton axles front and rear if I were gonna run a V-8, lockers, and 35s and use the throttle.

Drums to Discs
Back in 2007 Jp ran an article on upgrading from drums to disc brakes. I am assuming these will be manual discs brakes, and if so, can I still use the stock master cylinder or is there an upgrade for this swap? I will eventually go to a power booster, but not at this time. I’m having a hard time trying to find the caliper mounting brackets in the aftermarket, and I would rather go with new and not go to the bone yard unless I have to. Any ideas?
Dave F.
Via email

Dave, we’ve done several drum to disc upgrades over the years. Several years back I converted my Dana 25 then on my ’49 Willys to Chevy calipers and Ford rotors (“Timeless Tech, Drum to Disc,” April ’07). Mostly out of ignorance, I did not upgrade the master cylinder when I did this swap. I added an inline residual pressure valve to the front brake circuit and ran the stock master cylinder. Subsequently I got several letters from readers. Most loved the swap and wanted more details. Some said that without a master cylinder upgrade my Jeep would be a danger on the road. That was not the case. The Jeep stopped much better than it ever had before. Now having said that, on paper you should upgrade to a larger master cylinder with this swap to compensate for the larger volume of fluid that needs to be moved. I still have the flattie and still run my frame-mounted pedals with a custom- mounted Willwood master cylinder (“Braking Even,” Oct. ’12). Also, one of our friends is currently building a Flattie with the frame mounted pedals and he found a ’70s-era AMC car (like a Matador or Ambassador) master cylinder intended for manual disc front brakes and drums rear with ports on the right side (so you could mount it to the frame with some fabrication). Otherwise, if you have a later Jeep with the master cylinder mounted on the firewall, you can go to a CJ with manual disc front brakes.

As far as new caliper mounting brackets, I would have a look at Parts Mike, Somehow the company is able to keep new Chevy style caliper mounting brackets in stock and ready for mail order. Otherwise you can’t swing a dead cat without hitting a Chevy fullsize 4x4 with the caliper mounting brackets you’d need in the pick your part junkyards around here.

Soft Top Window Restoration
So I’ve got a fairly tattered old soft top for my Jeep, it gets used hard in the winter and then stored for the summer. The windows are getting really hard to see through, they are scratched and some are starting to turn reddish in some spots. Is there anything that I can do to get a few more years out of my top? I don’t know if you’ve looked, but the new ones ain’t cheap.
William McGillicutty
Via email

We’ve had pretty good results cleaning up the windows on an old Kayline top on our ’49 Willys with a clear plastic polish and cleaners from Meguire’s or Bestop. They help clean up small scratches and can help with reddish tint issues by helping the soft plastic windows clear up. The reddish tint won’t go away, but once the area is more see-through the tint is less of an issue.

Will This Work?
I’m trying to mate a NV3550 to a NP231J in my ’95 Jeep YJ anyone know if they bolt directly together?
Via forum

They should if the NV3550 is from a 4x4 Jeep or Dodge and your NP231J is from a six-cyl Jeep. If the transmission is from a late model 2WD Cherokee (which would be very rare) you will need a new tailhousing and maybe a new output shaft from a 4WD NV3550. If the transmission is from a 4x4 (Jeep or Dodge) it should have a large 6-bolt round rear mounting surface and a 23-spline output shaft (although T-case clocking may vary between makes and models). The mounting surface and output shaft should look like the photo below (of an AX15s output and mating surface).

If the T-case is from a four-cyl or ’80s-era Jeep, then it will have a 21-spline input gear that doesn’t work with the NV3550. If this is the case, you will have to disassemble the transfer case and swap in a 23-spline input gear or look for a different NP231J (with the 23-spline gear already installed). Now just to add confusion, there are different lengths of transmission output shafts and thus T-case input gears, so you’ll have to make sure your input gear on your NV231 is the 23-spline and should be the long input to match the short output of the NV3550. If your T-case is from a ’95-or-newer Jeep with a six-cyl that had a manual transmission, it should have the correct spline and length input shaft.

New Jeepers Welcome
I’m fairly new to the Jeep world. I recently purchased a stock ’97 four cylinder automatic TJ with the intent of it being a daily driver. The only modification from stock is I am running 30x9.50s on 8-inch wheels. I know! An automatic, yuck! But I have to have the auto due to medical issues. Where I live we have sand and mud, but mostly sand for off-road fun. I don’t know where to start with this build. I just want something simple so I can take the wife and kids out and get away for the day or weekend. Please help me get on the right path.
Noah Trevino
Avon Park, Fl

Hey man, one thing is for sure we were all beginners at some point. How you build your Jeep should be pretty closely tied to how it is gonna be used. But either way keeping it light weight is gonna be the best way to live with the underpowered 2.5L. Honestly if you are gonna keep it as a daily driver adding huge tires is not gonna help your gas mileage or highway speed. If I were you I’d stick to 30- or 31-inch tires, but look for some with more aggressive tread like a dedicated mud-terrain. Sure they will make more noise on the highway, but that’s part of the experience. You also could look into a budget-boost suspension lift to get your TJ a little higher off the ground. That will help with the occasional blast up the dune or through the muck. I’ve been running a Rubicon Express Budget boost with the company’s mono-tube shocks on my ’97 four-banger TJ for more than a year now with no complaints or issues. I’d spend more money on the upgraded shocks or look into some aftermarket shock absorbers like Bilsteins. Good shocks are nice and you use them every time you drive the Jeep, on-road or off. Also if you plan on playing in the mud more than the sand, get yourself a reliable winch. If you ever get really stuck out in the woods a winch can save your tail…especially if you have the wife and kids along for the ride. In the sand a winch is nice in theory too, but what are you gonna winch to?

It’s a ’75…er, ’76-’86 CJ
I just got the April issue and I love all of the CJ content! And yes, I want to be like Mike!

I have a ’75 CJ5 with a 304 V-8 I work on over the winter and drive in the summer.

One project I’m planning to tackle soon is a complete re-wire with a Painless kit. I would like to buy the CJ-specific kit to have the easiest, most plug-and-play time installing it.

Here comes my tech question: The Painless wiring kit says it’s for ’76-’86 (possibly because it is set up for use with the Duraspark ignition system?). I have a ’75 with the Prestolite ignition system. Will this Painless kit work by splicing in the proper, older style, ignition module plug? A lot of people recommend upgrading to the Duraspark system, but I’m not sure about that at the moment. There is the extra cost to do it, I already have a spare Prestolite module, my distributor/timing is all working well right now... I guess I’m just thinking “if it’s not broken, don’t fix it.” Can I simply splice in a different plug and keep the Prestolite system? Any other advice regarding this?
Darren Van Asseldonk
Via email

Thanks for the compliments. Mike is an awesome person and I am glad to have met him. After looking at the online Painless Performance catalog we found PN 10110 for ’75-’86 CJs. The catalog says several of the sending unit wires and the ignition wire are not pre-terminated for installation in various years with various power plants. They say the harness is not engine-specific so it seems like it will work with your CJ regardless of the ignition system. Just to be sure, I asked Jeff Abbot from Painless Performance who assured us this would work for you. He also told us that there are detailed instructions for wiring either ignition systems with PN 10110. Mike said he thought now might be a good time to think about adding a Davis Unified Ignition distributor and ignition. The HEI will provide more spark and power and only has one wire hook-up.

Get Bent…Er, Straightened
I have a ’79 J-10 with a 360ci V-8, T-18 tranny, and a Dana 20 T-case. The flange on the right rear axleshaft of my Dana 44 rear is bent. I’m having trouble finding a replacement shaft. All I can find are either five-lug or offset axles for a Quadratrac. Can you help?
Ray VanBuren
Shelby, NC

Well, you can keep your eyes peeled on where you can search for this and lots of other parts for your J-10. You could also check the “For Sale” section on which is a forum filled with FSJ information and like-minded FSJ fans. Even if a right-hand rear axleshaft is not in the for sale section, someone on the forum might know a good source for one. Another more expensive option is to pull your bent shaft and take measurements necessary to have a custom shaft built for your Jeep truck.

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