[cw0682]

Ok, so my 350 took out my T5 and clutch, I blamed it on mud in the clutch at first till I pulled the tranny and tried to spin the input shaft in neutral. 3rd gear is destroyed. So I'm going to blame it on diver, but I knew that the t-5 wouldn't hold up to the 350 with the type of driving I am wanting to do.

So now the adventure begins and I would like to get some input from you all, and all suggestions would be greatly appreciated.

Just to give you a rundown of my driving habits, my jeep is parked most weeks and I will be taking it out on the weekends, out old county roads and chicken paths mainly traversed by four wheelers, atv's and animals. I will be running 33x12.5 r15's MT with the prospect of going to a 35 inch tire in the future, but thats a suspenion lift and another post.

The only other thing that I have to keep in mind is I will be doing some high speed driving on 4 lanes to get to just about every destination so I want to maintain my road gears.

No matter what I will be retaining my D300.

Xmission wise I considered the idea of the getting a AX15 but then quickly discovered I would have to buy a new adapter to be able to bolt up to my 350. I haven't totally ruled this out yet.

Another option I am considering is a T18 or a SM465 wouldn't mind having a granny gear to crawl around a few hillsides.

Anyhow some of this has to do with tranny avaliability here in my area, I have yet to call the salvage yards, but hope to come to a conclusion this week of what I'm going to do as I would like to get this thing back on the road asap.

So I guess a question to you all is will I be able to cruise at 65 mph on highway with the 4 speeds with out much trouble?

2. what are your thoughts on this?

3. do you have any other suggestions or variants?

4. which swap do you think will be easiest on my driveshaft lengths?


I'm quite aware I'm going to be stuck with a decent bill when this is all over, but I found a good tranny guy that will rebuild one for me for 150 and i just by the parts. Hopefully what I find won't need rebuilt.

I have also considered doing a twin stck on the 300 while I'm doing this, but the terra low's will have to wait for another time.

But anyhow thank god I'm not married, or I'd prolly end up getting a divorce over this.

[berserker]

I have nearly the exact same plans, but I have a 360 (stock, HEI, quadrajet 4bbl) instead of a 350. My planned driving habits and use are similar to yours as well (trail driving but no rockcrawling, need good road manners). I steered away from the T-18 and SM465 because I wanted better on-road manners and could compromise on crawling for the time being (until I can put in a 4:1).

I researched this a bit, and found the best combination of affordability and durability was the AX-15. You will need to consider the difference in power between your 350 and the 360 (I'm not sure what that is). If you are planning heavily modifying the 350, you might need a heavier duty tranny.

I concluded that the AX-15 is nearly as strong as (some say just as strong as) the NV3550, which is touted as an ideal candidate for mild V8 power up to 35's (see Novak's site for example). The nice thing about the AX-15 is that you should be able to find one pretty cheap (YJs and XJs both used them for several years), it has 5th gear (and runs quieter than the NV3550). I got one with under 100k on it from a guy who was parting out his XJ for $100. The AX-15 to D300 adapter is about $150. The biggest expense is drivelines, which might require modification due to the ~2 inches of additional length of the AX-15, but this will likely be an expense that you will have regardless of which tranny you choose.

[Edit]: I completely overlooked your bell housing to tranny issues. You will need an adapter for that (which you probably already know) which will increase the cost of the AX-15 option by about $315.

Later on you can put the 4:1 gears in the D300 and it should be a solid set up.

[rustymudder]

im actually right in the middle of a T18 swap in my 82 CJ7. I currently have the t5 but with my 33s and 3.31 gears i never use my 5th gear so the lose of an overdrive isn't an problem for me. If your concerned about highway driving just drive it without using 5th gear. all of these trannys have 1:1 4th gears. If your comfortable with the rpms it holds in 4th then go with the t18 or Np435. I picked up a clean ford t18 from a local yard for $125 and amazingly it didnt need a rebuild. i took it to a tranny shop to install the adapter's new mainshaft but otherwise no new parts. with the t18 or the np435 you wont have to change your driveshafts. you'll have to get an adapter for the dana 300, but i believe their is a factory bellhousing you can use the sbc. If you still are go to www.novak-adapt.com they have tons of info on the best trannys, and adapters and bellhousings.

[Cutlass327]

So, why wouldn't you go with a Chevy trans, since you have the SBC? Then no adapter for the trans to engine. I know you'd need to adapt the trans the xfer case, but that'd be just replacing the tailhousing of the trans if I understand correctly.

[cw0682]

Originally Posted by Cutlass327

So, why wouldn't you go with a Chevy trans, since you have the SBC? Then no adapter for the trans to engine. I know you'd need to adapt the trans the xfer case, but that'd be just replacing the tailhousing of the trans if I understand correctly.

I'm leaning heavily in the direction of the sm465 because novak claims there set up with adapater and dana 300 with the sbc bell housing will get ya in the same length range as the original factory set up which should make for minor drive shaft changes if any, but my biggest concern is as state above road manners.


But then again, it is possible this 350 gets chipped up in the future, I am running TBI also.

[craptackler]

hey cw-

my '77 has an NP435 4-spd going to a Dana 300 4:1 w/ twin shifters AND it's up on 35s.
so far, i've only had it in the city and on the hwy up to about 60 mph or so.
it seems very manageable as a highway driver, note that you have to get very high RPMs to avoid bottoming out going into the next gear.
i'll be following along here to see what y' come up with, fer sure. this my first jeep, and my first project vehicle.

[berserker]

Originally Posted by craptackler

hey cw-

my '77 has an NP435 4-spd going to a Dana 300 4:1 w/ twin shifters AND it's up on 35s.
so far, i've only had it in the city and on the hwy up to about 60 mph or so.
it seems very manageable as a highway driver, note that you have to get very high RPMs to avoid bottoming out going into the next gear.

According to craptackler's sig he has 4.11 gears, but turning 35's powered by a 232.

CW is running a 350 w/ 33's (maybe 35's and a chip for the engine later). Don't know what gear ratio. Assuming 3.31, I don't think the 350 would experience the same "bottoming out" issues when upshifting.

That said, I would not let drivelines be the major reason why you choose a tranny. Sure they are a cost factor, but consider long-term drivability and your planned usage. To me, it is kind of like looking at buying a car (or Jeep) and looking at a 4 cylinder option because it has a lower sticker price and is more economical--not as fun to drive.

I haven't driven anything with a NP435, but I have driven a few T-18 equipped vehicles (a CJ and a few Fords). To me it feels like you are driving a delivery truck, not as responsive as some 5 speeds.

You want to be smiling while you are that 4 lane road heading to the hills, not dreading the drive. That said, you don't want to be falling all over yourself trying to slow down your Jeep on trails because your crawl ratio sucks, but you already mentioned the 4:1 T-case is a future mod.

Here's a comparison: lowest gearing followed by highest gearing

Lowest Gearing (for crawling):

T-5 first gear: 4.03 x Dana 300 2.62:1 x axle ratio: 3.31?= 34.9:1 crawl ratio

AX-15 first gear: 3.83 x Dana 300 2.62:1 x axle ratio: 3.31?= 33.2 crawl ratio [if you replace the 2.62:1 in the Dana 300 with 4:1 you get: 50.7:1 crawl ratio]

T-18 first gear: 6:32 X Dana 300: 2.62:1 X axle ratio: 3.31? = 54.8:1 crawl ratio

NP435 first gear: 6:68 x Dana 300: 2.62:1 x axle ratio: 3.31? = 57.9:1 crawl ratio

Highest Gearing (for highway driving)

T-5 5th gear: 0.86 x Dana 300 1:1 x axle ratio: 3.31?= 2.8:1

AX-15 5th gear: 0.79 x Dana 300 1:1 x axle ratio: 3.31?= 2.6:1

T-18/NP435: 4th gear: 1.0 x Dana 300 1:1 x axle ratio: 3.31?= 3.31

At 60 MPH with true 33's, your engine will be around 2000 RPMs with the T-18/NP435, 1700 RPMs with the T-5 (is that where you were?), and 1600 RPMs with the AX-15.

Someone let me know if my math is off (it frequently is).

Hope that helps.

[74CJMatlock]

I drive a 350/T-18 combo, and I love it. My Jeep's not a sports car, and I've never tried to make it one, so I'm happy. With any granny gear equipped vehicle, you'll spend your street time driving it like a three speed. The good news is that with the torque and power of the 350, you have a lot of room for error. That is, even in the low end of the RPM range, you'll have enough power to push the Jeep. All that being said, look into the T-176. It is also a four speed, but it's a little bit closer ratio than the 465 or T-18.

[jumbojeepman]

If you are running 3.31 gears? and 33" or 35" tires, overdrive is pointless, a 4 speed will be fine. I have a NP-435 in my F-150 (running 33" tires and a 400 engine, 3.5 gears) and it runs just fine on the highway at speeds of over 70 mph. I don't really need 4 or 5 gears (I rarely use granny,) either, I was passing cars up the steep part of I-40 in NC (going up the Blue Ridge) while towing a 6000 lb trailer in high gear.

My Jeep has a TH400 (1:1 final drive just like a 4 speed,) 4.10 gears, and 35" tires, and it runs down the highway just fine, too.

[berserker]

Originally Posted by 74CJMatlock

All that being said, look into the T-176. It is also a four speed, but it's a little bit closer ratio than the 465 or T-18.

x2. I neglected to mention that option. I've heard good things about them. I think they can be a little tougher to find than a T-18 or NP465?

Good to hear real world input from guys running these proposed set-ups.

[cw0682]

Yeah I had overlooked the T176 option also but i'm looking around in my area, someone had one of the chevy 4 speed rock crushers in the local classifieds last week out of a 1 ton dump for 200 bucks, I been trying to get ahold of him all day. I really think the chevy 4 spd adapted to my 300 would be the easiest and would most likely save my drive shafts, not that i'm opposed to haveing them modded I just don't see the extra need if I can get a set up lined up that is more that capable of doing what I wanna do without having to change them.

[cw0682]

Update....

Well looks like I may have lined up a SM465 and bell housing for 50 bucks, Should be able to go see it Thursday night, its a 2 wheel drive but Novak says they can adapt to it for my dana 300. Hopefully its a clean tranny and don't need anything only time will tell.

once again according to novak there is a high probability of reusing my existing drive shafts as this set up will be the same length as th t5 and dana combo.

Oh and why the heck is these adapters so dang high?

[berserker]

Sounds like it will be a good fit (if the tranny is in good shape).

Originally Posted by cw0682

Oh and why the heck is these adapters so dang high?

You are mostly paying for engineering/design and the manufacturer's exposure to product liability.

[UbelGeist]

I can get a name for you if you want, but there is a guy on this forum that will sell you a NV4500 mated to a Dana 300 for a reasonable price. That is were I got my setup for my 78 CJ7.

[cw0682]

Ok so I got my new old sm465 tranny for my jeep conversion, according to novak the sm465 could easily be adapted to the AMC bellhousings, and seeing how the bell housing I have now is currently a gm to amc adapter I think i'm going to try and reuse my cast aluminum adapter. The reason for this is the bellhousing that came with the tranny is a split 2 piece bellhousing missing the bottom half also know as the dust cover/inspection plate.


By the way anyone know who stamps CF on their adapters? I don't think it is a novak or AA.?