1980 CJ transmission question - JeepForum.com
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post #1 of 11 Old 01-29-2020, 08:55 PM Thread Starter
Jimmyj1957
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1980 CJ transmission question

The transmission on my 80 CJ slips out of gear (mostly2nd) and if I try to accelerate to 55mph I can hear the engine revving but it feels like the transmission is slipping and getting to 55 takes longer than it should. The VIN says it was built with a 4 speed manual transmission and a 6 cylinder engine. Somewhere along the line it was replaced with an AMC 304 V8. The guy I bought it from said it was a 304. I'm no expert on engines and certainly not AMC engines. Its clearly a V8. The numbers on the transmission indicate it's a SR4. My original plan was to have the transmission rebuilt. While researching the issue I'm seeing a lot of comments on the internet that a V8 and the SR4 are not a good match. Is this correct? I wasn't planning on replacing the transmission, however if there is a better more reliable transmission for this engine I'd be willing to consider it. I don't plan on doing any serious offloading with this vehicle, just a weekend driver with an occasional trip to the beach. Anybody familiar with this situation?
Thanks
Jim

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post #2 of 11 Old 01-29-2020, 10:43 PM
pedal2themetai
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HI, Manuel transmission don't slip but the clutch can ... put it in 2 give it some gas and try and start out if the motor revs and the jeep doesn't really move then its the clutch or set the park brake and again if the motor revs the clutch is bad.. a good clutch would kill the motor..
good luck
tim
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post #3 of 11 Old 01-29-2020, 11:54 PM
BagusJeep
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If you look on the side of the engine you will see 304 in raised numbers, if it is an AMC304.

The SR4 is alight duty car transmission that has no place in a Jeep. The native 4 speed transmission for that year that will fit the engine and transfer box and is reasonably strong is a T176/T177, plenty of other choices out there of course but to start a rebuild of the SR4 makes no sense, you may as well get a stronger box and rebuild that one. You can put a new clutch in but if the SR4 is jumping out of gear, it is time to think of a new box to be fitted at the same time. You may also need new driveshafts of the correct length but those can be ordered once the box is in and measured. You would also need a new gaiter for the shift lever.

Apart from being heavy, the transmission and driveshaft swap is quite straightforward.
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post #4 of 11 Old 01-30-2020, 08:08 AM
caseypotts
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Sound advice.

That SR4 was marginal in the 4 banger at 82hp, barely hanging on when offered in the 6 and living on borrowed time in a V8. (it sounds like yours is about to collect!)

I agree on the T176/T177 as the most straight forward swap into a V8. Other options include the T18/T19

I'm sure you have looked through the Novak website, but if you haven't I highly recommend it as a great resource.

Quote:
Originally Posted by BagusJeep View Post
If you look on the side of the engine you will see 304 in raised numbers, if it is an AMC304.

The SR4 is alight duty car transmission that has no place in a Jeep. The native 4 speed transmission for that year that will fit the engine and transfer box and is reasonably strong is a T176/T177, plenty of other choices out there of course but to start a rebuild of the SR4 makes no sense, you may as well get a stronger box and rebuild that one. You can put a new clutch in but if the SR4 is jumping out of gear, it is time to think of a new box to be fitted at the same time. You may also need new driveshafts of the correct length but those can be ordered once the box is in and measured. You would also need a new gaiter for the shift lever.

Apart from being heavy, the transmission and driveshaft swap is quite straightforward.
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post #5 of 11 Old 01-30-2020, 08:43 AM Thread Starter
Jimmyj1957
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Once again I would like to thank you for the help and suggestions. If I'm gonna do it, I may as well do it correctly. Yes I looked through the Novak site and thats what got me thinking the transmission I have isn't the best choice.
Jim
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post #6 of 11 Old 01-30-2020, 10:19 AM
bob4703
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You said won't be doing any serious off road so you may not need the truck type four speeds with the stump pulling grannie low 1st gear mentioned above. A three speed (T150?) may be what you need. I have a relative who as a teenager had a mid 80s CJ7 who liked to wheel in coastal swamps. After breaking two T5s his dad put a three speed in his Jeep.

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post #7 of 11 Old 01-30-2020, 01:00 PM
hp_lovecraft
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Quote:
Originally Posted by BagusJeep View Post
The SR4 is alight duty car transmission that has no place in a Jeep. .
I know this is the popular opinion, but I dont really agree with it.

The SR4 was used throughout the 70s, in most of the AMC I6 car engines, as well as Mustang V8s and AMC AMX muscle cars. It was certaintly rated for the output of amc I6 and V8 engines. It was revised in the 80s, and renamed the T4/T5 and is extremely popular today.

Is the T176, or T14 a better trans for the jeep? Sure. Heavy, and stronger. Perhaps not as road friendly, but more likely to withstand abuse from severe offroad use. But if you are only doing light off road, etc, the SR4 with the V8 is perfectly fine.

That is assuming it only needs a clutch. When mine went, I bought a cheap clutch from Rockauto for $100 10 years ago. It has worked perfect ever since. The nice thing about the SR4 is its light enough to easily pull up through the tunnel cover with your hands.

That said, I probably would not bother rebuilding. Popping out of 2nd gear is a sign of worn ball bearings, and play on the main shaft.
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post #8 of 11 Old 01-30-2020, 05:08 PM
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I really liked the T5 when I had it behind my 258. (I had the SR4 previously in my 81) Smooth shifting and had overdrive. Depending on your gear ratios the 5th gear is nice to have. Like may have said it's not a hardcore T18... but it also won't shift like your driving an old truck either. All depends on what you are building it to do. Mine sees up to 90 min of hwy time getting to my hunting spots and I'm not rock crawling it.

I want my two dollars!
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post #9 of 11 Old 01-31-2020, 12:33 AM
BagusJeep
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Quote:
Originally Posted by hp_lovecraft View Post
I know this is the popular opinion, but I dont really agree with it.

The SR4 was used throughout the 70s, in most of the AMC I6 car engines, as well as Mustang V8s and AMC AMX muscle cars. It was certaintly rated for the output of amc I6 and V8 engines. It was revised in the 80s, and renamed the T4/T5 and is extremely popular today.

Is the T176, or T14 a better trans for the jeep? Sure. Heavy, and stronger. Perhaps not as road friendly, but more likely to withstand abuse from severe offroad use. But if you are only doing light off road, etc, the SR4 with the V8 is perfectly fine.
You say it yourself, unsuited to off road. Apparently they flex under off roading conditions, which shortens their service life. They may do quite well in a road car and a mall crawler and may last a long time but they are not worth rebuilding to put back in.

I have a T18 with granny low and it is essentially a 3 speed on highway. The T176 is better suited to road and off roading and trails, the T18 is for those who need a seriously low compounded gear. In a J20 built to haul stuff out of deep muddy holes. the T18 wins. These transmissions can survive 40 years of use on rough roads and heavy loads with minimal maintenance

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1981 CJ7 258ci - Bagusjeep
1984 CJ7 258ci - Puthijeep
1981 J20 258ci - Gladys
1951 Willys CJ3A/MB/M38 - Little Willy
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post #10 of 11 Old 01-31-2020, 06:11 AM
Matt1981CJ7
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With the SR4, it not a matter of IF it will fail, it's just a matter of WHEN. For mine, it was at about 90K miles when it started jumping out of 1st gear on steep descents, and became hard shifting into other gears. I never cared for the awkward manner it shifted into reverse, either.

When I swapped my 258 for a 360 V8, the T19 transmission was the obvious choice for me. It has a synchronized 1st gear that you can get in 4, 5, or 6:1 ratios. With a D300 adapter, its length was almost identical to the old SR4, so my driveshafts remained the same. And the trans itself is bombproof, it will likely outlive my CJ.

Also, I think the common knock on the T-18/19 about shifting "like a truck" is due to most guys are using the Ford version with the long shifter. With the shorter Jeep CJ T-18 shifter, I find my T-19 shifts every bit as easily as my SR4 ever did.

Just my 2 pennies, and a pocket full of lint.

Matt


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post #11 of 11 Old 01-31-2020, 10:40 AM Thread Starter
Jimmyj1957
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Man, I cannot thank you guys enough for the help, suggestions, and opinions. This is truly the place to go for advice. In the interests of full disclosure, my only experience with Jeeps are limited to a 1995 YJ with a 4 cylinder and 5 speed. I bought it new and used it to get back and forth to work in bad weather and occasionally drive it to the beach. Did absolutely nothing to it and sold it after 13 years. I was not in the market for another Jeep (or so I thought). I stumbled onto this 1980 CJ 7 last June and thought it would be "fun" to have a CJ. I'm not a mechanic nor do I have the tools, skills, knowledge or working space to be one. So, I'm figuring out what I can do and having the serious work done by professionals. I guess what I'm taking away from all of this is while my SR4 can be rebuilt, it's probably not worth it and there are better options. Are these aforementioned transmissions easily obtainable in either remanufactured or repairable condition? I've been in contact with a shop (through a neighbor) that specializes in trucks and RVs. I don't know if what I want done is really "up their alley". Would I be better talking to a strictly transmission shop?

Once again thanks for all the advice.
Jim

Last edited by Jimmyj1957; 01-31-2020 at 10:52 AM. Reason: addition information
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