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July 2013 Your Jeep - Tech Questions

July 2013 Your Jeep Tech Questions Jeep Wrangler Engine
Verne Simons
| Senior Editor, Jp
Posted July 1, 2013

Answering Your Top Tech Questions

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
Via facebook.com/jpmag

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.
dawson-williams
Via jpmagazine.com

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, partsmike.com. 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.

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