trans question

cj5walt

Well-Known Member
Joined
Jul 28, 2009
Location
mooresville, nc
does anyone know if there is a "granny gear" four speed the will work in place of my t-18 in my cj5 with a 304 amc and a dana20 transfer case
 
cj5walt said:
does anyone know if there is a "granny gear" four speed the will work in place of my t-18 in my cj5 with a 304 amc and a dana20 transfer case
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T-176, but why would you want to do that? :confused: An SM465 is a good option, but will require another adapter.
 
i want the low gearing of the first gear because i will be doing alot of highway driving and do not want to have to use very low gears in the diffs
 
I dont fully understand your situation. Some T-18 have the granny low, some don't. How about finding a T-18 with granny low, that would be CJ from 76-79 or a Ford with the 300 cid inline 6.
 
are you sure that you have a t-18 in your CJ? I didnt think the cj5s came with that.

If so, I would find a t18 with granny and swap it. Im pretty sure the t-176 didnt have a granny though.
 
pretty sure its an t18, i admit i could be wrong, its the original 3 speed that came in it in 1974, never heard of a granny gear three speed though
 
Sorry, wasn't too clear on the T-176... low gear is around 3.5:1 (don't remember exactly)... but that's why I asked "WHY" :confused:

tknopp said:
Sm465 is a big and heavy tranny for a cj-5. I would look at putting in a sm420 instead.
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Just for info... Novak makes a 1" thick adapter for the SM465, and the tranny itself is only 1/8" longer than the T-18. It actually works very well in a CJ-5. I have sold a good number of twin-stick kits for the SM465/D20 combo. Also, the SM465 has a lower 1st gear than the T-18. It really is a good swap, but unless you have a Chevy engine it requires some bellhousing and front bearing retainer mods.
 
Going back to the base of the problem, your profile says you have 31" tires. what axle gear ratio do you have? What are you hoping to get, better offroad performance or better highway performance? A granny low tranny is going to drive a lot like your current 3 speed on the road, top gear ratio will be the same 1:1 that you currently have, and 1st will be so low, you probably won't use it unless your crawling. Offroad on the other hand, it would give you a much better crawl ratio
 
TKFireman said:
Going back to the base of the problem, your profile says you have 31" tires. what axle gear ratio do you have? What are you hoping to get, better offroad performance or better highway performance? A granny low tranny is going to drive a lot like your current 3 speed on the road, top gear ratio will be the same 1:1 that you currently have, and 1st will be so low, you probably won't use it unless your crawling. Offroad on the other hand, it would give you a much better crawl ratio
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I need to update my profile: curently have 33's with 3.54 gears. i have s set of 35's in the works

What im shooting for is to not go any lower than 3.73 gears to keep highway speeds comfortable (and as we all know the lower the gears you run generaly the "weaker" they are since the diameters of the ring and pionion get smaller, i am leaving the d30/44 axles) while at the same time improving the crawl ratio with the low gearing of first in the sm465 which has a 6.55 first gear compared to 3.1 of the t15. Both having 1:1 final gears. Then one day down the road adding a dana300 transfer case with 4.0:1 gears to further help offroad, gearing and ground clearance.

Hopefully this explains it, made sense in my head anyways :rolleyes: Im thinking this will be a good combination for a dual purpose rig like i am building
 
FWIW, my CJ has 4.10 axles, and is about perfect on the highway with 35" BFG tires, and a T18 tranny (1:1 final drive ratio). When I had 33's it would tach out on the highway, and this was one of the deciding factors to bump up to 35s. Offroad, the granny low 6.32:1 and Dana20 low range (2:1 I think)was fine for what I was crawling.
 
I have 35's and 4.10's right now. I turn around 2200 rpm at 55 with my t176. It does good on the highway, could definitely use a lower gear for offroad. Here is a good gear calculator, maybe it will help you with your decision.
http://www.grimmjeeper.com/gears.html
 
well i used the calculator:


how it is now:
t15, dana20, 33's, and 3.54 gears
low range crawl ratio is 21.56:1
rpm in 3rd @ 65 is 2343

with sm465, dana300 with 4:1, 35,s and 3.73 gears
low range crawl ratio is 97.88:1
rpm in 4th @ 65 is 2328



i think the new combination seems ideal. what do yall think
 
If those numbers work for ya, go for it, time to see how much that will cost.
Are you going to be happy topping out @65MPH? How many RPMS can the 304 handle? I have trouble letting people pass on the highway, even in a CJ. I was set up like you are now (33s, 3.54, 1:1), and when I hit "5 over" in a 75 zone, I well into 3000s RPMs, way past where my 258 wanted to cruise.

On the low side, 100:1 is low enough in my book. I was extremely happy when I swapped out the T150 (2.99 1st gear) with the wide ratio T18. Probalby because I was used to such a crappy crawl ratio, changing to 6.32 1st gear doubled it.
 
If your putting in a granny low tranny and a 4:1 kit in the t case, it may not be worth it to switch from 3.54 to 3.73. Changing gears is expensive for such a small change.

On the other hand, when I bought my jeep, it had 3.08 gears and 35's. it did not like taking off from a stop. the 4.10's fixed that without killing my top end completely. And of course, if your changing gears, time to think about lockers too......

Renegade T - my 304 is tired, but it will turn 3300 rpm, I don't like doing it for any period of time. 65 to 70 at 2600 to 2800 rpm is all i want to push it for any period of time
 
im cool lettin people pass, besides i usually take the scenic route when possible usually 55-60 mph rds. 304 will turn 6 grand:driver: wouldnt do it on purpose though
 
cj5walt said:
im cool lettin people pass, besides i usually take the scenic route when possible usually 55-60 mph rds. 304 will turn 6 grand:driver: wouldnt do it on purpose though
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Got mine up to about 3300 rpm one time, sounded like it was going to fall apart, couldn't imagine it turning 6000
 
that could explain it, I'm currently looking for a 360 to build and drop into mine, thinking of going to a 5 speed at the same time, not sure what I'm going to do yet either
 
TKFireman said:
that could explain it, I'm currently looking for a 360 to build and drop into mine, thinking of going to a 5 speed at the same time, not sure what I'm going to do yet either
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sounds good, wish these amc engines were easier to find and cheaper to work on bc they are great engines i could actuall use a set of heads for mine, i hear sb mopar heads work though??
 
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