3 speed vs 4 speed - JeepForum.com
 
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post #1 of 15 Old 05-15-2008, 08:22 PM Thread Starter
crawdad
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3 speed vs 4 speed

I am looking at another CJ and wanted to ask a question. This is a '79 model with a 3 speed tranny. I'm a little turned off by the fact that it is a 3 speed rather than a 4 speed, but then I've never owned a 3 speed so I'm not a very good judge. What are the advantages, if any, of the 4 speed over the 3 speed transmission. Thanks.


1984 CJ7, 258, T176, Dana 300-A Work In Progress
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post #2 of 15 Old 05-15-2008, 08:33 PM
ReconRabbit
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It would probably be the T-150 three speed. It is a very strong tranny and a good candidate for a V-8 swap.

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post #3 of 15 Old 05-15-2008, 08:36 PM Thread Starter
crawdad
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Quote:
Originally Posted by nzirbel View Post
It would probably be the T-150 three speed. It is a very strong tranny and a good candidate for a V-8 swap.
This CJ already has the 304 engine in it.

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post #4 of 15 Old 05-15-2008, 08:37 PM
SuB8HaVeN
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Yes, the T-150 is one of the best transmissions used in a CJ. You really don't lose anything with a 3 speed instead of the 4 speed. After all, they will both be 1:1 in their final drive gear (3rd/4th gear for 3spd/4spd). Some of the older AMC CJs (1977-1979) with the 4 speed will be a T-18A with a granny gear which is pretty desirable as it is 6.32:1 in 1st gear. You won't really be able to use 1st on the T-18A with normal driving, but it's great to have for crawling and towing. Other than that you'll find yourself doing better taking off from 2nd.

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1961 Willys 4x4 Wagon L-226 I6 T90 (restoration also in progress)
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post #5 of 15 Old 05-15-2008, 08:38 PM Thread Starter
crawdad
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One of the reasons I was asking is that I'm also looking at a 1980 model and it has the 4 speed in it. Not sure what model tranny it is but I'm guession T176. The 80 model has the IL 6.

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post #6 of 15 Old 05-15-2008, 08:41 PM
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If it's original a 1980 would have either the Tremec T-176 or Warner SR-4. The I6 came with both. If it is a straight stick above the boot it is a T-176, but if it has a bend about halfway it will be the SR-4. The SR-4 isn't the greatest transmissions, but should hold up behind the I6 as long as you don't beat on it.

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1961 Willys 4x4 Wagon L-226 I6 T90 (restoration also in progress)
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post #7 of 15 Old 05-15-2008, 11:01 PM
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The only advantage to a 4 speed over the 3 would be either the granny gear that T18 has or closer gearing like the 176. A little tighter gearing will help keep the motor in its powerband and not let the rpm's drop as much between shifts. The granny gear is usually only useful when towing or climbing a hill. The wider ratio 3spd won't hurt you any unless you're racing. I've got the T150 3spd and love it. I do a lot of mudding and have to rock it from 1st to rev and back to get myself out of trouble. it's much easier with the 3spd shift pattern. Ran it hard with my 258 with no problems. put in a 360 last summer and still ride it pretty hard and it hasn't missed a beat. But when it comes down to it, there are lots of other things I would look at before making a decision to go 3spd or 4. Mainly condition of jeep, price, engine, etc

77 CJ-7- AMC 360, Edelbrock cam, MC2100, Fenderwells, CJ T18/D20, Chevy D44/EB 9" rear, Trutrac f/r, 4.11, SOA, 1.25 lift shackles, 35x12.50 BFG KM2s, Shackle Reversal
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post #8 of 15 Old 05-15-2008, 11:24 PM
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My first CJ was a 79 CJ 5 with the 304 V-8 backed by a three speed. It has already been mentioned that the 4 speed trans. is nice due to having the extra low first gear, but in my experiences I would take the three speed over that four speed any day for a couple of reasons.

1: IT'S A THREE SPEED! It's not everyday that you hear about someone driving a three speed. So in my opinion having the three speed just sounds like more fun than the ol' "Four on the Floor." I had a couple of friends that have driven manuals ever since they could drive, but just knowing that it was a three speed instead of a five speed, THEY COULD NOT DRIVE IT, they nearly stalled it every single time until I took my keys away.

2:Also, as mentioned before, with the four speed, first gear is pretty well worthless. Whereas in my experience with the three speed, all three are pretty well rounded. You can realistically take off from a dead standstill in any of the three gears. Also, my third gear speed ranged from 15 to 75mph, yet on the trail first gear was plenty low for stock gearing. The 304 helps the three speed combo quite a bit. If you want for info(I have alot more to share), just PM me or reply to this post.

OlllllllO
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post #9 of 15 Old 05-16-2008, 05:37 AM
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Quote:
Originally Posted by crawdad View Post
...This is a '79 model with a 3 speed tranny.... What are the advantages, if any, of the 4 speed over the 3 speed transmission.
As other's have replied, since it's a '79 model there were only two manual transmissions available: T150 3spd, and T18a 4spd. Both are pretty indestructible. The T150 is fully syncro'd, the T18a isn't in 1st gear. Driving the T18a on the street is like driving a 3spd, as rarely would you use 1st gear. Unless you're 'showing off'.

The T18a is a heavy duty truck transmission. And it shifts like a heavy duty truck transmission. However, neither one of those transmissions are going to shift like a Ferrari does. More like my old Harley does....

In 1980 Jeep abandoned the heavy duty manual transmissions, offering the SR4 (light duty) and T176 (medium duty) four speeds. Of the two, the T176 is my preference. In 1981, the SR4 became the T4 (Tremec produced this in Mexico, IIRC), and the T5 (Non World Class-NWC) five speed was introduced. Opinions/experiences vary on the T4/T5, depending on how you use the CJ, will effect their lifespan. Also: 1980 was the end of the TH400, with Jeep switching to the TF999 (TF904 behind the I4).

IMO, for a mostly street driven CJ (with moderate wheeling), you cannot go wrong with either the T150 3spd, or the T176 4spd.

"In the end...It's all Hack."
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post #10 of 15 Old 05-16-2008, 09:02 AM
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I have the T18a and like mentioned it isn't useful in road driving. I have used it to climb and to go over rocks w/o having to constantly go in and out with the clutch, just put her in gear and let her roll
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post #11 of 15 Old 05-16-2008, 12:25 PM
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Quote:
Originally Posted by Ride Red View Post
My first CJ was a 79 CJ 5 with the 304 V-8 backed by a three speed. It has already been mentioned that the 4 speed trans. is nice due to having the extra low first gear, but in my experiences I would take the three speed over that four speed any day for a couple of reasons.

1: IT'S A THREE SPEED! It's not everyday that you hear about someone driving a three speed. So in my opinion having the three speed just sounds like more fun than the ol' "Four on the Floor." I had a couple of friends that have driven manuals ever since they could drive, but just knowing that it was a three speed instead of a five speed, THEY COULD NOT DRIVE IT, they nearly stalled it every single time until I took my keys away.

2:Also, as mentioned before, with the four speed, first gear is pretty well worthless. Whereas in my experience with the three speed, all three are pretty well rounded. You can realistically take off from a dead standstill in any of the three gears. Also, my third gear speed ranged from 15 to 75mph, yet on the trail first gear was plenty low for stock gearing. The 304 helps the three speed combo quite a bit. If you want for info(I have alot more to share), just PM me or reply to this post.

Interesting, out here a 3 speed is worthless. I have a T18 in my Cj7 and a T-150 in my cj5 and I can't wait to swap a T-176 in there. I LOVE the low granny gear on the T18. Granted we crawl rocks so we like the low gearing. Preference is just that and you need to decide how you are going to wheel your Jeep.

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post #12 of 15 Old 05-16-2008, 12:35 PM
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I have an 80 CJ-5 that came with the T-176. Prior to buying this Jeep, I had a 76 CJ-5 with 304 and the T-150. I never liked the 76 since it wouldn't gear down enough. The 80 with the T-176 has a slightly lower first gear and very good intermmediate ratios which goes very well with the lay of the land in our area which includes some long steep climbs. I have a rebuilt T-177 sitting in my storage shed that will eventually replace the T-176.
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post #13 of 15 Old 05-16-2008, 01:24 PM
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It's all about how deep first gear is, the deeper, the easier it is to take off, and the slower you can 'Crawl' the vehicle over obstacles...

Then once you are moving,
IT's about the difference between gears, or 'Jumps' between gears...

The more gears you have, the better your chances are of being in your engine's 'Power Band', instead of one gear being too 'Short' (engine RPM above the power band) and the next one being too 'Tall' (engine RPM below the power band)...

If you do mostly highway or back road driving, the three speed will do you fine once you stop trying to down shift into reverse when slowing down!
(ask me how I know about that one!)

If you are going to beat the crap out of the little jeep on obstacles all the time, you might want a 4, 5 or 6 speed transmission that ends with a 1:1 final drive...

If you are going to drive the jeep on highways and interstate highways, you might want a 5 speed with an Overdrive for better ground speed and fuel economy.
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post #14 of 15 Old 05-16-2008, 08:06 PM
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I have a 78 CJ5 with the T-18 they are nearly undestructable but expensive when the do get rebuilt. Also as stated 1st gear is not used for on road driving but is damned handy off road. the other drawback to the T18 it weighs a frigging TON! Does any one want to come over and give me a hand putting this thing back in?

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post #15 of 15 Old 05-16-2008, 09:21 PM
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Quote:
Originally Posted by Cherokeester View Post
Interesting, out here a 3 speed is worthless. I have a T18 in my Cj7 and a T-150 in my cj5 and I can't wait to swap a T-176 in there. I LOVE the low granny gear on the T18. Granted we crawl rocks so we like the low gearing. Preference is just that and you need to decide how you are going to wheel your Jeep.
Yeah I certainly understand your point on the crawling deal. Over here in the South, (where he is from) most of our terrain requires wheel spin to get through instead of the low granny gears. But you hit the nail on the head about it all comes down to your intended use for the Jeep.

OlllllllO
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