T-18 Tranny Question

T-18 Tranny Question

81CJ5baller

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1981 CJ-5 - currently strippd of body and gutting Iron Duke and frame off restoration in process!!!! Wooo Hooo......
I am T-18 Borg Warner to swap out my SR-4 due to my upsizing the engine. Question is the guy selling says it isnt "sync'd well on the low end good for rock crawling".

I am looking for something that will run well on road. Is this Wide Range tranny a decent option? I am not the best with the tranny's to say the least so help is appreciated.

Patrick.
 
It's only the 1st gear that is not synced, everyone I know that has a T-18 starts off in 2nd gear while driving on the street. 1st gear is for crawlin'... :)
 
What he ment was 1st gear isn't synchronized as it is a very low gear 6.something to 1. 2nd and up are synchronized. A good swap if you can do it would be a nv4500 early gm case good low gear and overdrive as well as good aftermarket support. Many have found there way into jeeps.
 
I need to learn to type faster! Sorry for being redundant.
 
I scored a T18 from a '77 CJ5 four years ago. Refreshed it, dropped it in, couldn't be happier. You'll love the low, low. 1st and reverse are not syncro'd and fourth is 1:1 (no overdrive) but if you're looking for a bombproof transmission that will take anything you can throw at it: you won't regret it.
 
Swapped my three speed for a T18 and couldn't be happier. 2nd, 3rd and 4th are the same ratio as the 1st, 2nd and 3rd on the old tranny and are good for the road. All synchronized so no trouble shifting. 4th gear is 1:1 ratio just like the 3 speed so no difference on the top end. First gear is for crawling and not being synchronized has never been a problem. The T18 is bullet proof. It's extremely large and heavy and putting it in is no picnic. Worth it though.

Tommy
 
Because it's wide ratio, a synchro'd 1st isn't needed. Like already said, for normal driving 2nd gear will be your starting gear of choice. 1st will only be used for crawling or starting if you're towing a really heavy load. If it was synched, downshifting from 2nd to 1st might cause damage due to the wide ratio difference.
 
Great info as always......This site is the best for guys that know their jeep stuff. Amazing..... Ok i have another option to consider....found an AX -15 5 speed which sounds like a great option for on road. It will need some adapters to mate up to the SBC and to put the Dana 300 on it but it sounds like a great mid duty tranny that would be a good on-roader. Any thoughts? I just found this AX and i dont know much about em but Novak seems to think they the best 5 speed jeep ever used. Now that might be that it is the ONLY 5 speed jeep ever used??!!!! Dont know. Anyhow....Jeep guru's...any thoughts???

PS....the T-18 is way cheaper to buy and may not need the adapters to put the Dana on so that is a consideration. I guess with that one, i am only worried about the high end 4th.....dont want to have to wrap the engine all day to keep above 60.
 
Jeep used other 5 speeds but yeah the AX 15 is a good one. Problem is 5 speed trannys are long. CJ5's are very short and never came with a 5 speed for this reason. It may be possible to make a 5 speed work with a SBC but it will be tough to fit.

The wide ratio trannies are not very nice to shift on road, slow and noisy... but beasts off road. You havn't mentioned anything about automatics. They are nice on road and the chevy Turbo350 is a very short tranny that would bolt to your SBC. You'd just need 1 adapter to your Jeep's transfercase.
 
I don't qualify as a guru, but that won't stop me from making some theoretical observations. My first thought about your 5-speed swap idea is that shifting 5-speeds is over-rated. (I drive one now in an underpowered Mazda pickup.)

But having done a bit of research I discovered that you may not be using first gear in either tranny, PLUS the AX15 has an overdrive 5th gear. That's sweet! I entered some random numbers into a calculator I found at Gear Ratio Calculator and see that while the T18 will have you spinning at about 2600 rpm at 60 mph, the OD gearing of the AX15 will have you spinning at just over 2000 rpm. That's VERY sweet!
 
Nv4500 .....low gear and overdrive 12.3 inches long and bolts to a smallblock and hydraulic clutch and strong.
 
Nv4500 .....low gear and overdrive 12.3 inches long and bolts to a smallblock and hydraulic clutch and strong.

The NV4500 Transmission - Novak Conversions

seems like an "ok" choice for me, but I'm more for road AND off road, and I'm in a CJ5. Every inch matters... lol

Novak has some good things to say about it, but also acknowledge there are better options...

:chug:
~ Jr
 
The gear ratio calculator you mentioned tinhorn is great. You have to also input your tire size and axle ratio to get an accurate rpm count. If you're going to be doing any crawling at all, it will be hard to beat the wide ratio T18. I am able to drive the freeways to the Rubicon and crawl through it just fine. I don't go much over 60 on the freeways and the rpm's are about 2200.

Tommy
 
Musta missed that Part.

They still say its a good transmission! :p It's just not the "top of the list" for cost and fitment issues.

I am able to drive the freeways to the Rubicon and crawl through it just fine.

Tommy, we need to get together for a Rubicon Run!

:rolleyes:

:chug:
~ Jr
 
Nv4500 .....low gear and overdrive 12.3 inches long and bolts to a smallblock and hydraulic clutch and strong.


The thing to remember with the NV4500 is that the main case may be 12.37” long but it requires an extension at the back that houses 5th gear and that adds an additional 6.5” to the overall package for a total length of 18.87”; far too long for a CJ5. The CJ T18 is 11.87” long plus a 1” Dana 20 transfer case adaptor which adds about 9” to the rear drive line over the NV4500.
 
I once looked at a CJ7/258 with the NV4500, that is a long tranny. On the inside the shift lever was located quite a ways back from where the T5 lever normally is. Underneath there was a 1" adapter between the tranny and bellhousing, plus there was CV joints on the driveshafts both front and rear. The owner worked at the local 4WPW where they installed it. My vote would be for a shorter T18 with say 3.73 gears for the freeway drives.
 
To get a synchronized low gear you need to step up to a T19 and they are scarcer than the T18.

Check this out:

http://www.jeeptech.com/convtrans/cjt18/

I swapped the T-150 in my CJ5 for a T18 and never looked back. It was an easy swap, direct bolt in. It will shorten your drive shaft slightly. I used 1"x1" rectangular steel tubing to space the skid plate down to get rid of driveshaft vibration. This was how it was done back then. 1st gear is 6.32.

I used to drive my CJ5 to the trail all the time. I drove from SoCal to the Rubicon many times with the T-18, 4:11s, and 33" tires. No problems. I loved that set up.

The shortest 4-speed is the SM420 with a 7.05 low gear. I run this now in my Chevy swap. A very balky shifting transmission. The T-18 is a really nice shifting transmission by comparison.

If your considering an x-fer case swap the 1980 short-shaft Dana 300 would be good; although they are very hard to find as the short shaft was used only in 1980. The short shaft version is really nice for CJ5s because it doesn't add to an even shorter drive shaft.

I measured for an NV 4500 swap and I found it too long. Either need to move engine forward or rear axle back or both. I don't believe I've ever seen an NV 4500 swap in a CJ5.

The TH350 will leave you with a very short drive shaft. If you ever plan on running a Dana 60 rear - plan on moving the axle back and the engine forward. Also the 1996-1999 4L60E is actually slightly shorter than a TH350 and it has the advantages of and overdrive and 3.0 first gear over the TH350s 2.52. You can swap a 2.75 into the TH350. With machining I'm told that you can use 3.0 out of 700R4.

For a nice simple manual transmission swap the T-18 is the way I would go. I miss my old T-18.
 

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