July 2012 Techline Reader Tech QuestionsPosted in How To: Tech Qa on July 1, 2012 Comment (0)
Metric Tire Math
Could you tell me the math conversion for metric tires into inches?
Let’s use a 305/75R17 metric tire as an example. First you have to convert the width (305) to inches by dividing by 25.4 (this is the number of millimeters in an inch).
305/25.4 = 12.01 inches
Then you multiply this number by the listed aspect ratio (75% or .75). This gives you the sidewall height.
12.01 x .75 = 9.01 inches
Then multiply the sidewall height by two.
2 x 9.01 = 18.02 inches
And then add the wheel diameter (17) and you will have the height of the tire.
18.02 + 17 =35.02 inches
So the 305/75R17 tire is 12.01 inches wide and 35.02 inches tall.
2 By 4
I recently paid off my truck, an ’04 Dodge Ram 2500 with a 5.7L Hemi. I love my truck but I need four-wheel-drive. Is it possible to change a 4x2 over to a 4x4 or would it be cost-prohibitive? My job was infantry in the military, not mechanics, so I would probably have to outsource the work. Considering the cost of parts and labor does this make sense?
SSG Carter Chick
D 3/141 INF Via email
Unfortunately it’s cost prohibitive to take on a conversion like this. It’s generally less expensive to sell the truck you have and purchase a 4x4 version of it.
FSJ Suspension Question
What leaf springs are you running on your current ’73 J-2000 with the 37-inch tires? I would imagine the same could be run on a ’77 Wagoneer. My Wagoneer has the 360, a TH400, and a Quadra-Trac T-case with Dana 44 axles front and rear. I’d like to just put a lunchbox locker in the rear and install the least amount of lift to clear 35- to 36-inch tires.
I don’t have a problem trimming some sheetmetal and re-working the inner fenderwells. I like the idea of staying spring-under to fight axlewrap but I’m not really into the whole lift kit idea. I was thinking of going spring-over with a set of flat springs, like 52-inch Chevy truck leaves in the front and either 56- or 63-inch Chevy truck springs in the rear with a track bar. What’s your opinion?
Can you give me a rundown of what’s been done to your J-truck? What springs did you go with for the front? Did you use a block, shackle flip, or lift springs for the rear? Your truck is spring-over in the front. Did the J-trucks come that way or did you go spring-over with the stock springs to get the lift you needed? I’m assuming you have the 360? What gears are you running with the 37s?
Are you running high-steer up front on the Dana 44?
The main problem is that the suspension on my ’73 is altogether different than what is on your ’77 Waggy. My truck has what is known as “post-mount” suspension. All ’63-’73 J-trucks have post-mount suspension. The springs mount to posts that protrude out of the side of the frame. The front and rear suspensions are spring-over from the factory. The good news is you actually have more options than me. Your Wagoneer has lots of lift kit options that fit the ’74-’91 models. However, your rear wheelwells are less trim-friendly because of the rear doors and the general design of the inner wheelwell. Trimming the front will be sort of similar to my truck but still a little different.
My ’73 truck is suspended by Hell Creek (www.hellcreeksuspensions.com) 4-inch lift springs up front. In the rear I simply flipped the shackles and used the stock leaf springs. I think you will be better off going with a 4-inch lift kit front and rear along with some trimming. It may seem cheaper to do the spring-over, but the additional parts needed can add up pretty quickly. For example, you will probably need to find a way to combat axlewrap front and rear, as well as lengthen the driveshafts (among other things) with a spring-over.
My truck doesn’t have axlewrap, but it doesn’t flex as well as the setup you’re considering. My springs are quite a bit stiffer.
My ’73 J-truck runs a 360 V-8, T-18 manual tranny, and a Dana 20 T-case with a 32-spline rear output. Up front is a smallish closed-knuckle Dana 44 and out back is a swapped-in junkyard Ford 9-inch from a ’74-’86 F-150. The axles house 4.10 gears. With the non-overdrive transmission and the 6.32:1 First gear the 4.10 axle gears provide both decent on-road rpm and half-decent crawlability in the rocks.
My truck does not have high-steer. There really is no way to install it on a closed-knuckle Dana 44 unless you build something custom. I simply ordered and installed a drop pitman arm from BJs Off-Road (www.bjsoffroad.com). I’ll eventually swap out the closed-knuckle axle for a stronger open-knuckle Wide-Trac Dana 44 from a ’74-’79 Cherokee or J-truck.
Death Wobble Dodge
I have an ’04 1-ton Dodge Ram 4x4. The frontend has had death wobble numerous times. Is there a package deal that replaces all of the problematic components? The front end of this 1-ton just does not feel like a 1-ton and I would like to make it much stiffer and not wobble. Of course I’m also on a tight budget. I feel like I’m constantly looking for any help I can get on frontend information. I have installed a BD steering box, new ball joints, tie rods, and ends, it still wobbled until I put a stock Dodge track bar on it. In your opinion, what do you think that is telling me?
No, there is no kit that I’m aware of that includes everything you need, but I had the same issue on my ’07 Cummins Ram 2500.
I replaced the factory ’03-’08 Y-style steering linkage with newer ’08-up T-linkage from the dealership. That helped a little.
I also installed Dynatrac (www.dynatrac.com) ProSteer ball joints. That helped a lot.
Your unit bearings could be bad, but that’s not all that likely. Jack one front tire off the ground and grab a long length of tubing and (with one end of the tube on the ground) pry upward on the tire to see if there’s any movement in the unit bearing or ball joints.
On my truck I installed a new ’09-up steering box from PSC Motorsports (ww.pscmotorsports.com). You’ll need a new steering shaft from Borgeson (www.borgeson.com) to adapt the newer steering box. All of this really fixed my wobble problem.
My factory steering box had a ton of slop at the sector shaft. I also installed a hydro-assist ram from PSC since my box came drilled and tapped for the ram, but in my opinion, a regular ’09-up steering stabilizer will work fine in most cases. The ram was an experiment for an upcoming article in Four Wheeler.
If your box is worn or has slop, you should replace it with the ’09-up box, but if not, you can install a steering sector shaft brace from PSC Motorsports. Other companies carry them as well.
Some aftermarket track bars can wear quickly and they often develop a lot of slop. It’s hard to beat the factory track bar and control arms for long life. Whenever possible, I choose to retain these items. The bushings in the control arms will last over 100,000 miles easily and the track bars are forged steel with really durable tie rod end(s) and/or rubber bushings. If you had death wobble and the factory track bar fixed it, I think you found your culprit.
I have a ’73 Chevy ¾-ton 4x4 with locking hubs and an NP205 transfer case. Is it bad to leave my hubs in the lock position with my transfer case in the 2WD position when I’m out at the desert in the sand.
San Diego, CA
Nope, it’s not bad at all. In fact you could even run it down the highway like that. Depending on if your 4x4 has a lift or not you may or may not notice some extra vibration from the spinning front driveshaft. You may also notice slightly poorer fuel economy because of the parasitic drag. But other than those two things you should be fine to run the sand in 2WD with the hubs locked. fw
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