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Newbie wanting help on engine and transmission choices for a cj7!

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8.7K views 29 replies 12 participants last post by  Boxcar  
2
#1 ·
Hi, i'm trying to redo my cj7 and was wondering first about the engine and transmission. Iv'e heard alot about jeep trannys going out at 30,000 miles quite alot on the newer wranglers thats why I decided on the cj7. I got a really good deal on a cj7 because the engine and transmisson were blown. I'm going to use it as my primary vehical and don't mind the noise and uncomfort of it.

So 2 things are important to me: Reliability and being able to drive 75 on the highway. So I need some expert advice on my engine and transmission options. But I don't want conversions I just want to choose from the factory choices for the cj7. Which transmissions are reliable and which ones are not? Same for the engine.

I tried researching on the net, but didn't find much from the reliability stand point. I would like input on both good and bad ones and some input on reliability of auto vs. clutch. I will be doing a combination of highway driving to work, and light off roading, so i don't need a hard core transmission that only goes 35mph.

Oh and side question, what is the top speed of the cj7? I know I asked alot but I really need and appreciate the help. Thanks in advance.
 
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#2 ·
For reliability I would say a 258 for sure, they are easy to find, have decent power, and near bullet proof. To be honest, unless you have a very finely tuned suspension, your probably gonna want to keep it under 65, these jeeps have a tendency to wonder at speed. Best trans for general street/light offroad would probably have to be the T176/177. The only overdrive trans would be the T5, which is a hit or miss. I've seen some handle hard offroading ok, and seen some blow up on the street. I prefer manual, but that's just me.
 
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#3 ·
x2 on the 258/T176 combo :thumbsup: I have that in my 80 CJ7, axles geared @3.08 and I can run 85 and still have pedal left. I don't do any rock climbing so the gearing is fine for trails and mud. I hope this helps :cheers2:
Good Luck
 
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#4 ·
Ok thanks for the great advice. Oh by the way the guy I bought it from said it had a 232 engine, but he wasnt sure of the tranny. More great advice will be appreciated, I would like more opinions on the matter and why 232 isnt as good as 258.

Are those the only factory cj7 trannys that are reliable? Any good auto's. I actually do prefer clutch but if the auto is more reliable, I would go for that. Oh and what would be a benefit of over drive? Thanks!
 
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#5 ·
I agree on the motor. The 258 is by far the best all around user friendly Jeep power plant. But not on the tranny choice mentioned. The T-18 is by far a better choice in Transmitions. wether you get the 6 to one or the 4 to one there is no compaering the two.And theay were a factory set up in both the cj5 and cj7. For autos the turbo 400 d-20 was also a factory option and a fairly bullet proof set up . early t-5s are adequite but I wouldn't go there. If your Jeep is stock it will drive fine at 70 mph . The problem is that most cj"s aren't stock. If you don't know what you are doing you can realy screw up the drivabillity of a cj with a poorly exicuted lift or poor maintanance.....1974 cj5 401,T-18,twin stick terra low d-20,44s,33s, lockers (detroit),10 point cage,warn 8274,
mallory unilight, 4" skyjacker lift, hooker headers (in frame) I don't have all day so I will cut the list short.... I do this for a living.......... What year 7 did you buy and what was the origanal drive train? As far as top speed Depends on your gears and guts...
 
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#6 ·
Ok the 258 as the engine is settled unless more people disagree. And we have a t-176, t-18, and th400 on the good list for trannys. I will pass on the t-5, is the t-4 a bad choice as well? What are transmissions to definetly stay away from?

To answer your question it is a 1982 and I bought it from the original owner that didn't know anything about mechanics, but it is all stock no lifts or anything. He said it was a 232 for the engine and he didn't know about the transmission, but its a clutch, I think axles are dana 30 and amc 20, I guess standard carbs and im not sure about the transfer case or differentials. Hope this helps.
 
M
#17 ·
bryce1974 said:
Ok the 258 as the engine is settled unless more people disagree. And we have a t-176, t-18, and th400 on the good list for trannys. I will pass on the t-5, is the t-4 a bad choice as well? What are transmissions to definetly stay away from?

To answer your question it is a 1982 and I bought it from the original owner that didn't know anything about mechanics, but it is all stock no lifts or anything. He said it was a 232 for the engine and he didn't know about the transmission, but its a clutch, I think axles are dana 30 and amc 20, I guess standard carbs and im not sure about the transfer case or differentials. Hope this helps.
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Your 82 has a 258 engine, It will run all day at 75 mph and is capable of getting 20+ mpg highway.

Why do you think the engine or tranny is blown? I got mine cheap because the engine was 'blown' and oil was puking into the air filter like 'blowby' on a blown engine. That symptom was fixed by simply fixing the PCV system and the emissions canister. Basically the emissions system just needed a tune up.

Trannies are also hard to 'blow' on a stock machine, real hard. Usually the symptoms of not being able to shift without grinding can be fixed by using the correct 'special' GL4 gear oil. Folks use the stuff off the shelf (GL5) end up with syncros that don't work. A fast oil change fixes that. Or the clutch has gone bad...

You should take some photos of what you have and post them to a free site like photobucket so you can post the links here for us to go see.
 
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J
#7 ·
The big question here is what year did you buy? There's two 'generations' if you will, 1976-1979 and 1980-1986. While you can most certainly swap parts back & forth between them, you have to do a little finagling to deal with the different t-case setups and get the skid plate/crossmember mounted up. The T-18 is an excellent trans, however it is basically a 3 speed since 1st gear is a crawl gear and of little to no use on the street...you definitely won't use it in everyday driving. If you have an 80-86, it's not a direct bolt up to the t-case. The 232 is basically the predecessor to the 258...I don't recall that it was ever used in the CJ-7 and am eating dinner right now so I'm not going to go look it up...you can check out www.jeeptech.com to see what was used when and common swaps & fixes. The 258 is bulletproof and with some carb & ignition tweaks can make a nice daily driver powerplant. Reliabilty is going to be up to YOU...it's an old, used vehicle, so you're going to have to build in any reliability.
 
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J
#8 ·
T-4 is basically a T-5 without the overdrive. For your use, while it's not the most durable trans, the T-5 is probably the best choice since it has overdrive. It's fine as a street trans if you aren't abusive and take proper care of it. TF999 would be your choice for an auto, that was the stock unit for your year. The TH400 was only used with q-trac (full-time 4WD) pre-'80 so it would require adapting to your Dana 300 t-case or you'd have to get one out of an older FSJ that's mated to a Dana 20 t-case (which then gets you into fitting it up to your later model frame). You're going to need to spend some time and money on the suspension & steering at those speeds.
 
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B
#10 ·
Wrong again as I mentioned earlyer the t-18 is available in both 6-1 or 4-1 1st gear Most cj5s came with the later wich maks it a 4 spd it was also mated to the d-300 in the 80s as an option which is what your jeep most likely has in it. Now
I am not just ringing the t18s chimes But you must realize THIS IS THE MOST utilized transmition ever used in light trucks VERRY available- Used in every thig Fords Jeeps Corn Binders And yes even some chevys. It will work in an 82. Your jeep is pas side drop so you need eather a d-20/ or a d-300 transfer case. By the way it has a 258 if it is stock .... the t-176 is an ok tranny .You will not find as many out there on say craigs list or ebay becaus thay are not as universal. The TH-400 you can find in most Wagoneers from say 72-76 STAY AWAY FROM THE QUADRATRACS. If you do opt for the T-18 You will pay more for the 6-1 and it will more than likely be a Ford tranny . You will need to use a conversion carrier bearing and a Ford 11" clutch disc to mate this to your engine. You may also need a mid year (76-80's) Bellhousing. Look on the Novac web site thay will provide you with all the info you need to inst. a T-18 into your Jeep......Boxcar
 
J
#12 ·
Boxcar said:
Wrong again
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Again? When was I wrong the first time? ;)

as I mentioned earlyer the t-18 is available in both 6-1 or 4-1 1st gear Most cj5s came with the later wich maks it a 4 spd it was also mated to the d-300 in the 80s as an option which is what your jeep most likely has in it.
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The T-18 by every account was not used past 1979 in the CJ and was never mated to the Dana 300...you'll have to provide a source for this one. It's certainly *not* most likely what he has, the T-4 or T-176/177 is. The only T-18/D-300 combos I've ever seen or heard of were either Scouts for the single year that they used a Dana 20 compatible Dana 300 or they were Ford T-18's that were adapted to the Dana 300.
 
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B
#11 ·
I forgot to mention the venerable T-15 three speed . It was a factory set up in most cj5s and cj7s equiped with v-8s great reliable tranny. Not very exciting to most Jeepers and very cheap. You should be able to find a good one mated to a d-20 for a couple of hundred bucks.. As far as reliability I don't think anyone will argue that this isn't one of the most reliable trannys Jeep ever used.....Boxcar
 
J
#13 ·
That would be a T-150, used as the stock tranny up until '79 (the T-18 was an option *then* not in the 80's). SR4, T4, T5, T176/177, TF999 are the 80's offerings.
 
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J
#14 ·
Bryce. also need to ask what your skill level is (mechanics, fabrication). I have my own ideas based upon what you've posted, but I've been wrong before...
I try to tailor my advice to the audience. What I would recommend to a newbie is not what I would recommend to a seasoned wrench monkey and vice versa.
 
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J
#16 ·
In that case I would suggest either a 4.0 or 4.2 w/4.0 head & EFI backed by an AX-15 or NV3550 for stick (5-speed OD's from Wranglers) or 32RH (newer designation for the TF999) or AW-4 (4-speed OD from an XJ) for auto. Alternately, GM 4.3 V6 backed by a TH700R 4-speed OD auto. There's other more advanced stuff out there too like Mopar Magnum swaps and Northstars that would work nicely for your usage. Pretty much boils down to time, money & skill level, but none of it is rocket science. Tackling things like this is what brings your skill/experience level up...you don't get there by not doing them. You just have to spend the time to do the research and consult with folks who've done the same swap.
 
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B
#19 · (Edited)
I was refering to his "d300 "ad being stock
The t-18 was available through 1980 mated only to the d20 and only in cj5s and only an option in early 1980 (not standard) . I own one. Look I don,t need to get into a technical "I'v read moor mags than you " argument over this .The Jeep you have will axcept a mirad of drive train combos. Most of what has ben mentioned on this forum will work in your jeep .And most of the setups mentioned are the first thing replaced by most profitiont builders. I havent bin posting for 5 or ten years.But oh yea, I have bin building Jeeps for 30 years. Not in my back yard or on paper .If you are going to build a Cj. Do it right the first time. Use the strongest and if you can most available parts ,Not just what came in the Jeep by year. Don't fall for fads< like switch blades. Or cheap shackal lifts or excesive body lifts ALL JUNK.( I'm going to date myself here) But I have noticed over the years That most people that come to us to build there jeeps are trying to convert a newer jeep into a 72n to 76 cj by removing all the ofending pats that have found there way into the Jeep over the years. And replacing them with "what used to come in stock Jeeps".A perfect example of this is the AMC 20 rear end Or the dana 35 . Almost allways are swaped for a 44 . The ax5 , or t-176 Tranny. The 231 transfer case. The vacume actuated dana 30 front end.The list is long, and sullied. Look for a set up that is over kill. Not just adiquit. Or you will become a very profitiont REbuilder of jeeps Due to repitition. Or the need to rebuild what you have previously done. I have allways strived to build bullet proof rigs. No matter what the owner plans to use it for ( Plans chainge). Parts don't . For most people, it is better to wheel than wrench. If I have ofended any one I am sorry (and so is my spelling) I guess old guys can't spell , or at least this old guy. For a given budjet it is no more expensive to do this job in a manner that will run for years then to just put it back the way it was. You probubly have a 258 , T-176 , d-300, amc-20, d-30 set up now .AND IT HAS FAILED........ Take a hint . Listen to all advice (It's free) weed out the (well thats what I run guys) the ( I can out spend you guys) the (techno warriers) And in allot of cases the old guys like me who should be at the shop working on a carb not sitting here trying to type. Look for sound advice from people who are proud eanough of there work to post pics in the profile section. Or if thay heve the time and know how a (build thread) verry cool. Then you can se the proof of there labors. Good luck and most of all have a good time. Get to know your rig . And if possible, do as mutch of it as you can yourself . You will gain an understanding of how your rig works so if it does break you will know how tio fix it. By the way the aformentioned crossmember conversion is probubly the easyest one on the entire jeep. I still stand behind the 258-T-18 d-20 (or d-300 with addapter) drive train it is as close to bullit proof as you will find...........Boxcar Owner of "Resurection Iron Works" We build Jeep's
 
#24 ·
Boxcar said:
The t-18 was available through 1980 mated only to the d20 and only in cj5s and only an option in early 1980 (not standard). I own one.
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I think what you own is a leftover 1979 CJ-5 that was sold as a 1980 and that the reason it was an "option" is because they only had a limited supply of leftovers left.

Bryce, I agree with the 258/T-5/D300 recommendation. I had an 85 CJ-7 through college that was my daily driver/cross-country driver which never grew beyond 31's until after I got out of school and got a real job. Kept in good tune and the trans maintained, that combo with 3.31 axles yielded 20mpg and neer failed me until I parted it out. The T-5 now lives on in another JF member's CJ. Just don't go too tall on the axle gearing. I got away with 3.31, but if I did it again I would make 3.54 the minimum.
 
R
#20 ·
If I was building a CJ7 to be my primary driver that would only see very little dirt I would swap in an AX-15 from a 1988-1999 jeep if I were you. I believe It will bolt right up to the 258 or you could swap in a whole 4.0L, Ax-15 from a donor YJ. The adapter to mate it to the Dana 300 is only $120 from Novak

However, if you plan on any wheeling or bigger than stock tires I would consider an upgrade above just good enough. I agree with boxcar on the T18, I like overkill so when my T5 kicked the bucket I swapped in the Ford T18. It isn't that bad on the street either. I drive my jeep almost every day and its nice to have one less thing to worry about in my Jeep. But I don't drive on the interstate with my Jeep, so I only need to go up to around 60mph.

go to Novak's site: Novak Jeep Conversions - Home
They have all the info you need on swapping Jeep trannies.
If its worth doing, its worth overdoing.
 
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#21 ·
I appreciate all the helpful advice, I believe I have enough info to put me on the right path. Like mike mentioned I should take it to a mechanic to see if the engine and tranny are really blown, that is something I should definately do before I throw a ton of money at this, since the guy I bought it from had no mechanical skills he could have sold me something that could be reasonably priced to fix. I cant get it to start.

I do have one other question, boxcar why do you say stay away from the quadra-trac... is it unreliable? full -time 4wd sounds good. Thanks.
 
J
#23 ·
bryce1974 said:
I do have one other question, boxcar why do you say stay away from the quadra-trac... is it unreliable? full -time 4wd sounds good. Thanks.
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It uses an offset rear axle, very inefficient fuel consumption-wise without a part-time conver$ion kit, most of the time doesn't have low range (you'd have to find a donor that has it), limited production, parts are hard to find and costly when you do find them, chain drive and the chain wears out/stretches. It's not the AWD/full-time 4WD of today. The TH400 auto that came mated to it is bulletproof and can be adapted to your Dana 300.
 
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J
#22 ·
No 'I've read more mags' argument going on (I've personally got about 25 years at this). Misleading info was given and I cleared it up...no need for anyone to be put off by that. If you'd seen some oddball factory T-18/300 combo, I wanted to hear about it (look at the wording of your post again). What tends to happen when people have amassed YEARS of info is that when they explain things to someone in a short format like these forums, they cross things up/mis-speak..I've done it before myself. Now let's move on with helping the guy out.
 
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B
#25 · (Edited)
To answer your question about the quadratrack. Jeepscate coverd it prety well. It is a dated system that never worked vary well . It also creates allot of drag (rotating mass ) which leads to bad bad gas mialage.Not to mention the loss of ground clearence caused by the HUGE transfer case If you deside on the ax15 you could save a bit of money (most take off piles have one in it .Thay were(in most cases) mated to the 231 tranfer case . Yes an adapter is available to mate it to the d-300 but if your going to spend money on an adapter and a tranny and by the way DRIVELINES to install the ax15 you could do better....... No my 80 is an 80 not a 79 Dec of 80 to be exact it was probly specialy orderd,I have allways thought so any way. It is kind of an odd duck. But it is as delivered..38000 miles.. It will be my daughters grad. present if she makes it......HA HA . Also you guys need to realize I am on the extream west coast actualy any ferther north and west and you will be swimming . Rigs delivered especialy in the 70s and 80s vary from coast to coast.Could be caus we are so close to Canada. A tall mountain on the east coast is a speed bump out here......Boxcar. PS: By the way I just pulled a t-15 (71-75) NOT A T150 (76-80) diferent tranny, from a 74 today including the d-20 and long bell housing. Won't be reusing it if any one needs it. Its prety fresh.Oh and I am sorry for the disagreement with you Jeepscate. I don't read manny mags nor do I ever see the need to respond to them. With jeeps I have found that due to the many owners of the Jeep name and the mirad of manufacturers.Published info conserning Jeeps is scetchy at best NOTHING suplants expieriance........ Boxcar
 
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#26 ·
Boxcar said:
No my 80 is an 80 not a 79 Dec of 80 to be exact it was probly specialy orderd,I have allways thought so any way. It is kind of an odd duck. But it is as delivered..38000 miles..
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Not trying to get into an argument or anything...just stating what I know.

My all original 1980 CJ5 was built in Dec. of 1979 and is equipped with a D300 & T176 4 spd. I know it's build date because it's never been repainted and the build sticker is still there on the inside of the tub.

You have an odd duck indeed.

FT
 
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