You can swap your automatic for a manual. As long as you are going to use the factory AX-15 transmission, it's a bolt in deal. The problem is, there's a heck of a lot of bolts. Here is a rough list of the parts you will need for the swap:

AX-15 transmission with bellhousing, transfer case adapter, and shifter
Transfer case shifter linkage from a 4.0 TJ with AX-15
New flywheel, clutch assembly, and pilot bearing
Clutch slave cylinder
Clutch master cylinder and hydraulic hose
new pedal assembly from a manual trans TJ
New driveshafts
ECU from a manual trans 97 TJ w/4.0
New transmission mount

"I have a 1996 Jeep GC, with a Auto Transmission. My Jeep GC is in the shop because the RPM's would reach 3000 rpm between 15 to 30 mph. The mechanic tells me that the band has collapsed and the bearings are shot. So the transmission needs a complete overhaul. I've been reading alot of articles about the problems with this transmission. I have limited knowlege about transmissions, but am afraid I will have to bring the Jeep in again no matter how well it is maintained. What is your advise?"

You didn't mention which engine/trans combo you have or how many miles are on your Jeep, but it doesn't really matter. I haven't heard any complaints about the automatics in Grand Cherokee's at all. Have you installed larger tires without a gear swap? Do you tow trailers/vehicles very often? Have you changed the fluid and filter at no more than 30K intervals? I suspect either the failure was a one time fluke, or you've really been working your Grand Cherokee.

Either way, installing an auxilary transmission cooler is always a good idea. The cooler you can keep your automatic, the longer it will last.

"I have a 1985 S10 Blazer, with a 2.8L V6, 5 speed. What would be the result of replacing the rear 4.10 gears with 3.73s w/govloc positraction and leaving the front gears stock(4.10)?"

The result would be broken driveshafts, U-joints, transfer case or any number of other components in your drivetrain once you shift into 4wd. The axle ratios MUST match front to rear. If you replace the rear with 3.73's and left the front with 4.10's the rear tires would be trying to travel much faster than the front. The bind created in the drivetrain will lead to failure almost immediately.

"I have a 1998 Wrangler TJ Sport, with a 4.0L inline 6 w/ Dana 44 rear end (3.73). I have installed a RE 4.5" lift and 33x12.50s. I get around 12 miles to the gallon now and was wondering if I upgrade to 4.10 or 4.56 gears, would this help mileage or make it worse? I've heard so many different opinions, don't know what to think."

I would swap to 4.56's and I would expect a very minimal mileage improvement. I absolutely do not believe you will hurt your gas mileage with the swap. As your Jeep currently stands, you are most likely having to apply way too much throttle to maintain speeds on the highway. To bring the engine RPM's back to an efficient operating level, you'll need to bring the overall gearing as close as possible to stock, which means installing 4.56 gears. Even if the mileage improvement is minimal or non-existent, you'll certainly appreciate the increased performance of your Jeep.

"I have a 1997 Jeep TJ Wrangler, with a 4.0/5-speed. I am running four inches of lift and 33x12.50, axle ratio 3.55:1.  I would like to swap axle ratios as opposed to T-case gears (4:1) for obvious reasons (power, gas mileage, etc.)  I run Moab often and like the crawl-ability on the rocks.  I also like to get there from Salt Lake City in less than four hours.  Will 4.56's be low enough for serious crawling and if I swap in the new 4.88's (D30/D35c) will I be limited to a top speed of 65?  Also, will this put extra stress on an already weak axle?"

I'd go with the 4.88's. Your top speed will not be limited to 65 due to the gears. In fact, you're engine will be turning around 2950 rpm's at 75 mph. The 4.56's will work fine too on the highway, 2750 rpm's at 75 mph. I think the lower 4.88 gearing would be much appreciated when you visit Moab as well as just improving performance for around town driving. The strength difference between the two ratios would be negligible.

"I have a 1989 Comanche, with a 4.0/Puegot 5-speed. Recently my transmision went south, now I'm looking for something to replace it with. Dependable, and possibly a bolt-up, are what I'm looking for. Do you have any suggestions as to what I could do. Even if I have to swap out the old 4.0l."

We replaced the peugeot tranny in our Project 1989 YJ with an AX-15 transmission more than three years ago, and it's still holding up great. The swap is a super easy bolt in and costs much less than a rebuild of the Peugeot. For more info, see http://www.dirtroad.com/article.htm.

"I have a 1992 XJ Sport, with a 4.0/5-speed. Dear Grant, I have a few questions, all inter-related. I'm REALLY hoping SOMEONE can help me with this... I have a '92 XJ which I am about to spend some really tall dollars on to make it more offroadworthy. I was hoping to build it up with an OME suspension/31x11.5 tires, new D44 axle in the rear with 4.10's and an ARB locker. I ASSUME that the front axles would require the similar amount of beef that the rear has, as the transfer case does not discriminate (or does it??). It occurred to me that I could save SOME money in the front by using the Warn full-float axle kit in the front on my D-30. I'm guessing that such an installation would make an ARB locker in the front unnecessary, since an automatic (Detroit?) locker will only come into effect when I lock the hubs. Is this true? And why haven't I hear of anyone doing this to XJ front axles before? Won't it fit? Are there disadvantages to this? Do you have any recommendations for me? I want a bulletproof buildup so I won't have to worry about being stranded offroad. And yes, I will be building up all related drivetrain components also (Slip-yoke, driveshaft, etc.). Thanks."

I don't believe you'll need a Dana 44 axle up front. When in 2wd, the rear axle takes all of the power making a rear axle swap a worthy upgrade. However, when in 4wd you're splitting the available torque evenly between both axle assemblies. The most engine torque the front axle will see would be half that of the rear axle in 2WD conditions. The front axle of your XJ is already a full floating model, meaning the axle shafts do not carry any of the weight of the vehicle. All of the weight is supported by the wheel bearings. Warn does have a front hub kit for the XJ and installing it is an excellent idea, it's too bad the factory didn't do it in the first place. You could save a few dollars by using a Detroit Locker instead of the ARB in front as it would be disconnected as long as the hubs are unlocked and it would not cause any driveability problems.

"I have a 1995 Jeep YJ, with a 2.5 4 cyl. auto. I have just installed a Rubicon Express extreme duty 4.5" lift on my YJ. Upon completion, we noticed that the slip yoke was dangerously close to coming out of the tailshaft of the transfer case. I know that the ideal fix would be the slip yoke eliminator and CV driveshaft, but can't afford to go there right now. After confering with a fellow Jeeper that is quite knowledgeable, it was decided to add 1.5" to the rear driveshaft. Am I safe in doing this? I've heard that under full compression of the suspension you can drive the slip yoke right into the tranfercase if your shaft is too long. That is why we only added 1.5". What do you think?"

With your new springs I think it's almost impossible to bottom out your rear suspension. You will probably be able to have one side of the axle or the other actually contact the bumpstop, but due to the stiffness of the springs I don't think you could ever compress the suspension fully on both sides at the same time, unless you jump it...high. I would go ahead and lengthen the driveshaft so that it will have a safe amount of engagement in the output spline. Just to be safe, purchase some longer bumpstops as well to keep the springs from compressing to the point of bottoming out the slip yoke and damaging your transfer case.

"I have a 1988 Wrangler, with a 4.2 six. I understand a company called BDS (Big Dick Suspension) makes a product which allows the replacement of the vacuum operated front axle engagement machanism, with a manually operated cable driven mechanism. Do you have any infomation on this, or know of a place in Southern California where I can purchase this? Thanks."

The "Rock Lock" from BDS is a good way to eliminate the troublesome vacuum front axle engagement system on early YJ's and XJ's. It will also allow for 2WD low range for easier steering for anyone with a front locker installed since the front axle isn't automatically engaged when the transfer case is shifted. You can contact them directly to find the nearest dealer (517) 279-2135.

"I have a 1980 CJ7, with a 304/ NV4500. I just put a NV4500 in my 1980 CJ7.  The vibration from the now 20-1/2" drive shaft is severe.  The shop that shortened the drive train says its the angle.  I think it is out of balance.  I have several jeeps and the 17 inch drive on a 1980 CJ5 is about the same angle as that on the CJ7.  I plan to send the drive shaft to another shop for balancing.  Any advice beyond this would help."

If it's a new driveshaft, are there any balance weights on the shaft to suggest whether they have attempted to balance the shaft or not? If not, have it balanced first. If they shortened your existing driveshaft, it still needs to be rebalanced. If it still vibrates after balancing, you'll need to measure the U-joint operating angles and determine whether they are correct for your style of driveshaft, eyeballing it won't get it close enough. For more information on how to do this, see http://www.dirtroad.com/articleb.htm

"I own a '97 TJ SE. The engine is completely stock with an automatic transmission. Tubular bumpers front 7 rear, plus a hardtop. I've been informed that thanks to the 4.11 gears, the four banger can roll 30" tires without problems. Is it true? I'm planning to get a K&N filter, and maybe a Borla or Gibson exhaust, plus Jeep's rims for the 30".

Is it true that I won't encounter any problems with the 30"? Hope you can help me."

Four cylinder TJ's with automatics were equipped w/3.73 gears, not 4.10/4.11 gearsets. Four cylinder/5 speed TJ's came equipped with the lower gear sets. You will notice a decrease in power with the larger tires. Some, if not all of this decrease could be made up with the modifications you are already planning.

Editor's note: If you think your gearing may have been changed, please visit our Determine Gear Ratio page to find out how to tell what ratio you have.

"I have a 1998 Jeep TJ, with a 4.0/5spd. Grant, my TJ has a Dana 35C w/Trac-Loc.  I'm thinking of going to a locker of some sort, and was wondering if I would need to change the carrier to an open diff type."

Your Trac-Loc differential serves double duty as the carrier as well, meaning the ring gear bolts directly to the Trac-Loc diff. The ARB air and Detroit "full-size" lockers also serve as carriers. If you choose one of these lockers, you won't need to buy a separate carrier. If you decide to go with an EZ Locker/Lock Right or the new Detroit Gearless Locker, you will need to purchase a new carrier with the locker. My advice would be to go with the Detroit or ARB. The price will be about the same using the Detroit (the ARB will be a little more due to the cost of the compressor) and you'll have a much stronger setup than using one of the "mini" lockers that only replaces the spider gears.

"I have a 1993 Wrangler YJ, with a 4.0L/5 speed. Hello Grant, I would like your advise on what type of lockers and what type of gear ratio I should have. I do alot of 4x4-ing in places like Death Valley and many other rough areas. I have a 4" lift with 33x12.50 MCII. I'm also a single parent so money is always a big factor.  Please help."

You've probably heard it before, there's a rumor that Jeep actually stands for "Just Empty Every Pocket". The installation of new gears and lockers is one of the most expensive modifications the typical Jeep owner will make. New gears and lockers will cost around $1500-1700 installed. I'd strongly suggest having the lockers installed at the same time as the gears. You could install an EZ Locker or the new gearless locker by yourself later, but the installation of the locker would have been free had it been done along with the gears. Here are a few more tips that might save a little money. Find out whether or not you will have to replace the carrier for your gear swap. This will depend on what gears you have now and which ones you want to install. If you do require a new carrier, than purchase a Detroit Locker. The Detroit replaces the stock carrier. Any money saved by purchasing an EZ locker (which fits inside the stock carrier) instead of the Detroit would be reinvested in a new carrier anyway. The Detroit would make for a stronger and more reliable setup at virtually no extra cost. If you don't need a new carrier for either axle, than you can purchase the EZ Locker or Gearless Locker later down the road and install them yourself. These tend to be a little cheaper than the full size lockers and you will avoid laying out a huge chunk of change all at once.

I'd suggest at least running 4.56:1 gears in the axles. There's supposed to be a new 4.88:1 gearset coming soon for your axles, so you may want to hold out for those. Play around with some of the formulas at gears.htm to determine which gearset you'll be most comfortable with.

"I have a '97 Jeep TJ, with a 2.5L /5 speed. What gear ratio would you reccomend if I plan on using my TJ for a daily driver with 33x12.5's on it? Its the I-4 with the 5-speed.  Also I may occasionally run 35's for the trail."

I'd recommend the absolute lowest you can go with your existing axles, which is 4.56:1. Even 4.56's aren't low enough to bring your Jeep back to it's original 4.10 and stock tire gearing. You'd need something in the neighborhood of 4.88's to offset the increase of a 6" taller than stock 33" tire.

"I have a 1984 Jeep CJ7, with a AMC 150/4 speed. Will I actually see better performance if I switch to a replacement carburetor?  The ads say 'up to 18% increase in horsepower.'  What is your experience?"

You're wise to be doubtful of such huge performance gains with a simple carburetor swap. If you wish to purchase an aftermarket "performance" carb, feel free. Just don't expect a huge improvement in performance (assuming your existing carb is tuned properly). Any power gains that may be had will most likely occur at the peak of your engine's operating range where your engine is likely seldom used anyway.

"I have a 1985 CJ7, with a 258/T5. I just purchased my Jeep for a very low price, but the T-5 transmission has several broken gears. I would like to know if the Borg Warner T-5 is the same T-5 that is put in the Mustang and will it work in my CJ-7?"

The Mustang and Jeep T5 transmissions are very different. The Mustang T5 can be modified to install into your CJ, but the expense far outweighs the benefit. Custom adapters would have to be purchased along with some internal modifications to the transmission in order for it to work. Even with that accomplished, the gear ratios in the Mustang T5 are biased to street use and would greatly degrade the off road capability of your CJ.

"I have a 1974 Jeep CJ5, with a 304 T-15. Can you tell me excactly how much horsepower the 304 has?  Mine is stock and I was just wondering. Thanks."

According to my reference, your '74 with a 2bbl carb produced 150hp@4200 rpm and 245 lb. ft. of torque at 2500 rpm with an 8.4:1 compression ratio.

"I have a 1999 Jeep Wrangler, with a 4.0/5spd. Hey Grant, I've got a real stumper for you.  My 99' 4.0 TJ is rated at 181hp and 222lb-ft of torque. The 4.0 Cherokee is rated at 190/225 respectively, and the Grand Cherokee 4.0 is rated at 195/230 respectively. My question is:  Why and How? Are these the same engines or not? Is it possible to do whatever it is they do to the Grand Cherokee to my Wrangler? This would be a big increase to the already potent 4.0 in the Wrangler. Your words of wisdom would be greatly appreciated!!"

My understanding is that the difference in power ratings between the XJ and TJ is entirely in the exhaust system. A quality aftermarket exhaust should bring your TJ up to the XJ level with little effort. Check out some of Turbo City's dyno proven products. The new Grand Cherokee (WJ) engine is an entirely different story though. Chrysler made some huge changes to the 4.0L for the WJ only. The displacement is the same in the WJ, but they don't have much more than that in common.  For the scoop on the new WJ and the it's much improved 4.0, check out www.dirtroad.com/articleg.htm.

"First off I just wanted to say thanks for a great web site and a great magazine.  Secondly, I have a question about my '94 Cherokee Sport.  I have been upgrading the 4 litre engine with the normal mods (K&N filter, Jacobs Omni Magnum ignition and a Gibson Cat Back) but I really want to put headers on.  Some people have told me that I would be wasting my money on headers because the computer and O-2 sensor would compensate and adjust the fuel curve negating any power increase I would see normally.  Is this true?  Would a high performance chip and headers be the way to go to see the most power increase, or will the headers perform fine by themselves with the factory computer?  I really am at a loss for answers here and any help would be greatly appreciated. Thanks from a loyal Jeepster."

The factory header on the 94 XJ's is actually quite good. It is not the old, crack prone cast iron manifold found on older non HO 4.0L engines. The 94 manifold is stainless steel and an exceptionally efficient design considering it is a factory piece. I'm sure there are other aftermarket headers available that may produce another pony or two over the factory piece. I personally don't think they are worth the labor effort, and certainly not worth the expense, when replacing the factory HO manifold. However, if you're wanting to squeeze every last bit of horsepower from you 4.0L than it may well be worth it for you.

Your computer will compensate for any airflow increase made available through a new header. Rather than work against you, the computer will actually be your ally when making minor performance mods. The computer acts as a professional tuner, perfecting your air fuel ratio. It takes readings from your O2 sensor and others to ensure the proper fuel mixture for the current operating conditions, regardless of altitude, attitude, engine speed, or engine temp. Try that with a carburetor! If a new header allows more airflow out of the engine (and consequently into the engine as well), then the 02 sensor will automatically "tell" the computer to add more fuel to match the increased amount of incoming air. The greater the airflow through an engine, the more fuel you can burn, and the more power you can make.

I'm not a real big fan of "high performance" computer chips for a couple reasons. The majority of the chips available through the aftermarket do little more than advance your ignition timing and enrich your fuel mixture. This is why all of them specify 92 octane fuel after installation. Advancing your timing can create more power, but at the risk of "pinging" or detonation. A high octane fuel is less likely to cause detonation than a low octane fuel, therefore allowing more ignition advance. Running a rich fuel mixture does little more than burn more fuel and create more emissions. Again, you can gain a couple horsepower by running a slightly rich fuel mixture, but you're going to pay for it out the tailpipe in two ways. The gas you're burning is expensive super unleaded, and you're burning more of it.

The fuel mixture is changed by either modifying the signal from the computer, or installing a very cold thermostat. Your stock computer will automatically enrich the air/fuel ratio when the engine is cold to prevent stalling and aid in smoother running. The stock computer will also advance the ignition timing when the engine is cold for the same reasons, but it will only advance the timing when the engine is cold since a detonation problem is much less likely with a cold engine. The "performance" from these chips comes from fooling the computer into thinking it is cold, and adding a high octane fuel to cover up the lie.

"I have a 79 Jeep CJ, with a 258 6cyl. What was the stock horse power and torque rating for the 258 ci 6cyl?"

The output of the 258 varied through the production years. According to my reference, the '79 258 produced 114 hp@3600 rpm and 196 lb. ft. of torque @ 2000 rpm.

"I have a 1991 Ford Bronco, with a 351 W/Auto. I recently had my fuel regulator, oxygen and another SMOG sensors replaced, but now I have a little hesitation in the acceleration.  It will also, on occasion, do a little rough ideling, it tries to rev from about 700 to 1100 RPM's when I come to a stop.  The fuel gauge or sensor is broken (being repaired next weekend).  Was wondering if you knew what could be causing this?  Would a new brain help?  Is the gas gauge sending a mixed signal?

Also, it has a tendency to shift hard between 1st and 2nd gear when I'm on the throttle hard, but shifts smoothly between all the other gears and shifts smoothly when I'm not on the gas too hard.  What is this caused from? Torque converter going out? 

Thanks for any and all help!!

Oh, yeah, I'd like to get a Jacobs electronic ignition, would you recommend this?  If so, which one?"

Ford makes it very easy to diagnose their EEC-IV EFI systems. Go to your local bookstore and purchase a book called "How to tune and modify Ford fuel injection". Then purchase a hand held code scanner available from your local parts store for around $30. Read the self diagnostics section in the book, then hook up the scanner to find any problems with any sensors, valves etc. The Ford's diagnostics are very thorough, and the book will be a very good tool to help you solve any problems you will most likely find with the scanner. In the unlikely event that the scanner does not produce any error codes, check the manifold for a vacuum leak. The gasket between the upper and lower intakes are notorious for leaking.

"I own a 97 4.0L TJ I running 35" Thornbirds and I want to add a Detroit E-Z locker in the stock dana 35 in the rear to hold me over for a few years until I get a Dana 60. Would this work and last, or do you have any other recommendations?

Also I was looking at a mile marker winch and I was wondering if they are that much better than the electric winches."

I wouldn't recommend the EZ locker with 35" tires. Detroit has just introduced the "gearless" locker that is quite a bit more stout than the EZ locker but can still be installed in your driveway. Look for a summary of the Gearless Locker in our "Project 94 XJ" very soon.

I don't think the Mile Marker is necessarily "better",  it depends on what your needs are. There are big advantages and disadvantages to each. The Mile Marker hydraulic winch does not work if your engine stalls, period. Even if your engine quits running, the electric winch will still get you out of your predicament and give you a decent spot to repair your engine to operating status again. On the other hand, the electric winch is a huge drain on your vehicles electrical system when in operation. You may need to add a second battery (a good idea anyway) and/or a higher output alternator. Personally, I still lean toward the electric winch.

"I have a 1993 Wrangler YJ, with a 4.0/5 speed. How can I find out what my axle, gearbox, and transfer case gear ratios are?"

The only 5 speed offered in a 4.0L powered YJ was the Aisin AX-15. The AX-15's ratios are as follows:

You have an NP231 transfer case, it's low range ratio is 2.72:1. The ratio is also stamped in the ID tag on the back of your transfer case. Your axle ratio will either be 3.07:1 or 3.55:1 depending on which options were ordered with your Jeep. The easiest way to verify the ratio is to check the ID tag on the front differential cover, one of the above ratios will be stamped in it. If the tag has been removed then you'll have to count the number of driveshaft revolutions per tire revolution. To do this, raise one end of the vehicle so that the tires are off the ground. Place a chalk mark on one of the tires and a similar mark on the driveshaft. Rotate the driveshaft by hand, counting the number of revolutions required for one full tire revolution. If you turn the driveshaft 3 times, you have the 3.07:1 axle gears. If the driveshaft turns 3 1/2 times, you have a 3.55:1 ratio.

"I have a 86 CJ7, with a 258 I-6/T-5. I am interested in swapping my 258I6 with a 242 I-6 instead of adding an aftermarket MPI system to my 258 I-6.  Upon rebuilding a 242 I-6, I am wondering if it is possible to place the crank from a 258 I-6 into a 242 I-6 increasing the 242 I-6 stroke from 3.41" to the 258 I-6's 3.90" stroke?  I am assuming that the vibration dampener and fly wheel would require replacement. Any other adjustments necessary?  Thanks for your input Grant!"

The 4.0L and 258 cranks do share many of the same journal dimensions, but that's not the only thing to consider. The deck height of the block and valve clearances are just as important. Use of a 258 crank with stock 4.0 rods and pistons would cause more than a little interference between piston and cylinder head. It can be done though, but you'll need to confer with some experts in the Jeep I6 field first. Hurley Engine Service (205/251-1472) has been using 258 cranks in 4.0L blocks to produce 4.7L engines for some time with hp and torque results equalling that of small block V8's. Even if you don't want to purchase their stroker kit, I'm sure they'll be willing to share some more info with you.

"I have a 1984 CJ7, with a 258/4sp manual transmission. My engine seems to be in rough shape (and with only about 70k miles on it.) I just need to know the best way to go, fix it or replace it with something else.  Here's a list of the problems I'm aware of: There is a knocking underneath that seems to come from a rod bearing. The engine uses about a quart of oil every 200 or so miles. (Half of it seems to be leaking out near the bottom end) In addition, oil is getting into the air filter from the vent hose attached to the valve cover. The oil pressure gauge jumps between 5 and 40 psi erratically. I'm not sure how good the power in the engine is because I have no basis for comparison, but it's doing good to get me to 70 mph on the interstate. Also, the engine likes to shut off in cold weather. This CJ is my daily driver - I have a 180 mile daily commute, and every once in a while would like to take it off road.  Its clear to me that the previous owner did not take care of this one, but I want to make sure its reliable and runs as well as possible.  Should I have the engine rebuilt, put in a remanufactured one, do an engine swap, or what? Thanks a lot!"

I really can't tell you whether you should do an engine swap or not. Engine swaps tend to be extremely expensive and can lead to a whole host of other problems such as broken transmissions, axles, or driveshafts due to the added power. When considering an engine swap, you have to consider all of the other components behind the engine as well. Considering your long commute, it may be best to find a reputable engine shop in your area that is familiar with the 258 to perform a rebuild on your existing engine. During the rebuild, the shop could perform some performance modifications to your engine to improve power over stock. With a healthy and warmed up 258, you should have better mileage than with a V8 swap (not to mention a lot more cash in your pocket), and enough power to exceed 70 mph without a problem.

"I have a 1995 Jeep YJ, with a 2.5L/Manual. I've seen a lot of Dana axles advertised in the four-wheel mags.  I just wanted to know what exactly "Dana" is?  (Is it a type of axle or a brand name or classification?)  And are my Jeep axles "Dana"?  If so does my boyfriend's truck (Mazda '89 B-2600i)have one?  His rearend is going out, would it be better to switch out a Toyota axle in its place, if so, would he have to change out the gear ratio in the front?  Thank you --Annette"

"Dana" is a brand name. Yes, your YJ is equipped with Dana axles: Dana 30 front, Dana 35C rear. With Dana axles, the greater the model number (i.e. "30" or "35") the greater the load capacity of the axles. As for your boyfriends Mazda, (is he dating you because he'd really rather own a Jeep?) his rear axle is not manufactured by Dana. Rather than get into any swap complications, he should just rebuild his existing Mazda axle. Better yet, he should sell it and buy a Jeep.

"I have a 1981 Jeep CJ7, with a 258/auto trans which I purchased used and have dissassembled to the frame. The vehicle came with a Quadratrac transfer case and I assume that the axle is an AMC 20. (I'm aware that this drive train was not available on '81 models so is it possible there were changes made?). I plan on using the Jeep for mostly highway driving and some offroad trails in AZ. I'd like to put in a 4-spd. manual trans and a positrac rearend. I have a Dana 44, T-18 man. trans, and model 20 transfer case from an earlier model CJ7 available to me. I'm considering also switching to a V8 motor (Chevy 350 or Ford 302) for added horsepower. I would like to know if changing the rear axle has any impact on the front axle such as gear ratios and what would be a good combination? Also, I did a compression test on the motor I have now and it's in good shape, so would it be more economical to outfit it with a fuel injection unit and headers, and could I achieve comparable horsepower to a stock V8, or does it make more sense to do the engine swap? Any recommendations ? Thanks for your help."

If you remove the Model 20 rear in favor of the Dana 44, you will need to check the gear ratios of your front and rear axles to ensure they match. If they don't match, engaging four wheel drive would guarantee the breakage of at least one driveline part as the front and rear wheels would be trying to travel at different speeds. If your front axle ratio is 4.10:1 and the rear is 4.09:1, you're fine. If the front is 4.10:1 and the rear is 3.07:1, you're going to have to switch the gears in one of the axles so they will match. I really can't recommend a specific ratio for your Jeep without knowing what tire size you intend to run and just how much highway travel you intend to do in your CJ.

You can build the 258 to produce comparable torque numbers with a stock V8, but getting 200 hp out of one is going to cost a considerable amount of money. Since you already have your Jeep completely stripped to the frame, and the rest of the drivetrain that you intend to use is capable of handling stock V8 power for the long term (with the possible exception of your front axle), I'd recommend the engine swap. There's not really a clear as to which manufacturer's V8 to use in your case. The Ford and AMC engines would be very easy (i.e. cheap) to adapt to the T-18, but the Chevy is the cheaper engine to obtain parts for. The choice is yours.

"I have a 1959 FC 150, with a F4-134/ 3spdT90. I want to swap the stock axles on my Forward Control from the original 5.38 to make it more drivable, top speed being about 48mph.  The front axle is a Spicer 44-IF and the rear is a Spicer 44-1 both front and rear ratios are 5.38.   It would be easier to swap the ring and pinion, correct?  What would be compatable with the stock Spicer running gear.  I am looking to make this my daily driver and have to make it more driveable.  Any thoughts, comments, I need info. Thanks"

New ring and pinion gears are still available for your Jeep. A swap to a 4.10 ratio may bring your top speed up a bit, but your Jeep is going to feel as if it's lost a little power due to the taller gearing. On older Jeeps, there is a better method to gain higher top speeds without losing the existing low gearing. For a little more than the  cost of a ring and pinion swap in your Jeep, you can purchase a Saturn Overdrive unit. This overdrive attaches to the back of your transfer case, is fully synchronized, and won't require any driveshaft modifications. To make the deal even sweeter, you can install it yourself in your own driveway. The Saturn offers a 27% overdrive; the same effect as having a 3.92:1 axle ratio when engaged. For more information on the overdrive unit, contact Advance Adapters (www.advanceadapters.com)

"I have a 1987 XJ Wagoneer, with a 4.2L? I bought this truck about a year ago and have a question about the VIN coding. My VIN number (1JCMR7513HTxxxxxx) indicates that the truck has the 4.2L engine, according to my reference.  Could that be correct?  I have not heard of the 4.2L being installed in the Wagoneer and suspect that my reference book is incorrect. If you could shed some light on this it would be greatly appreciated."

The 4.0L engine was introduced in '87. If you have a fuel injected inline six cylinder in your XJ, than it's the 4.0L. The 4.2L engines were always carburetted from the factory and were never used in the XJ.

"I have a 1985 CJ7, with a 4.2, 5 speed. Keep it up! My Jeep has the model 20 rear axle, and all we hear is that they are not very reliable. Is there a way of knowing, without tearing the whole thing apart if it is in bad shape. It runs OK, and I changed the oil in it before putting it asleep for the winter, the oil was clean. I run 32-inch tires and do a bit of offroading nothing really serious. Is it worth a swap?"

Without tearing it apart for an inspection, you'll just have to look and listen for tell tale trouble. If the seals aren't leaking, the axle tubes are straight,  it doesn't display excessive slop, and runs quietly, call it good.

The model 20's weakness and poor reputation was not generated by the gears themselves. The model 20 actually has a slightly larger ring gear than the Dana 44.  The trouble is in the OEM axleshafts. The original axleshafts were a two piece design that used a pressed on outer hub flange. It is very common for the hub to "strip" resulting in a loss of power to the wheel. If you have the original axleshafts, I would strongly recommend upgrading them to an aftermarket one piece design. There are numerous manufactures of these kits and price ranges from $300-350. With the one piece axles in place, your model 20 should give years of trouble free service considering your stock drivetrain and intended use. Unless your planning any engine swaps soon, I would not recommend spending $1200 dollars or more on a new axle assembly.

"I have a 1997 Jeep Wrangler SE, with a 2.5/Standard 5 Speed. I bought my Jeep brand new, and instantly I noticed that when I shifted into 5th gear, there's a rattling noise, and the dealer just told me it was common with the 4 cylinder motors, but now it getting worse. The 4th gear is making the same noises, and I'm just barely hearing it in 3th gear. The Jeep has about 25,000 mi. and has had all the drivetrain fluids changed at 15,000 mi. Any tips or answers would be a great help. I do plan to take it to the dealer to have it check out again."

When you return to the dealership, insist that they look into the problem more carefully. Blaming the transmission noise on the fact that you have a four cylinder engine is ludicrous.

---

Dirt Road Magazine is sponsored by Turner 4WD Parts Co.