6 speed

[Jeep Driver]

9 hours ago, Strokermjcomanche said:

I'm not sure what you're getting at , I mentioned the Nsg370 (6speed ) several times . I'm not spending $3500 on any trans , and I won't buy a junk one either . 

 

Has as anyone seen or done the Nsg 370 swap in a Comanche or Cherokee??? 

What do you plan on doing for a CPS?

[Eagle]

6 hours ago, Strokermjcomanche said:

While I agree with you Eagle some things have changed in the past 30 years . When these trucks first came out the speed limits were lower ( 55-65 around me ) now we have a lot of 70mph highways around here and when I'm going 70 I'm getting passed like I'm standing still. I don't plan on doing 80mph , but 75 mph is probably a realistic number ( and is a possibility that some highways will be raised to that ) so the RPMs will be even higher , and I would like to hear a little bit better too . 

 

AMC introduced the family of engines that eventually became the 4.0L all the way back in 1964. The nationwide move to reduced, 55 MPH speed limits didn't arrive until 1973 or 1974, when we had the first so-called gasoline shortage. Before and after the 55 MPH era, we routinely cruised at 70 t0 75 MPH, with the tach hovering around 3000 RPM or a bit more, and the engines lasted 200,000+ miles. Gas mileage was (and is) better below 60, of course, but that's a function of resistance when you're trying to push a brick on wheels down the road at speed. The engine RPM isn't the major factor in that.

 

It's your money and your vehicle, but IMHO you're heading toward making a mistake.

[johnj92131]

11 hours ago, Eagle said:

 

AMC introduced the family of engines that eventually became the 4.0L all the way back in 1964. The nationwide move to reduced, 55 MPH speed limits didn't arrive until 1973 or 1974, when we had the first so-called gasoline shortage. Before and after the 55 MPH era, we routinely cruised at 70 t0 75 MPH, with the tach hovering around 3000 RPM or a bit more, and the engines lasted 200,000+ miles. Gas mileage was (and is) better below 60, of course, but that's a function of resistance when you're trying to push a brick on wheels down the road at speed. The engine RPM isn't the major factor in that.

 

It's your money and your vehicle, but IMHO you're heading toward making a mistake.

 

In 1964 when the 232 was introduced, the factory offered a 3 speed plus overdrive transmission as an option for the high mpg crowd.  The overdrive offered a 30% (or so) reduction in engine speed on the highway.  So idea of slowing the engine down at higher road speeds is nothing new.  Overdrive units go back to the late 20's and 30's.

 

Remember the O.P. wants to reduce engine noise caused by higher than needed engine speed.  The easy way to cut down noise is not to make it in the first place!!

[johnj92131]

Adam,

 

Some simple math tells me that the 6 speed transmission is not going to help you with 70 mph engine speed.

 

Your current final drive ratio  with the NP3550 and the 4.10 rear end is:  .78 x 4.10 = 3.198

 

Your current final drive ratio with the 6 speed and the 4.10 rear end is:   .83 x 4.10 = 3.403

 

Regear your NP3550 for a .73 5th with your 4.10 rear end and you get this:  .73 x 4.10 = 2.993

 

Just for reference - You started with an NP 3550 and a 3.07 rear end:  .78 x 3.07 = 2.395

 

And if you keep the current NP3500 and change the rear end to 3.73:  .78 x 3.73 = 2.909

 

Notice the 2 combinations in bold print?

 

 

 

 

[Jeep Driver]

You can read below from someone who claims to have done the swap. If you believe him, I don't. 

He claims it does not matter what position the CPS is on the flywheel. 

 

Apparently there is a 3 wire CPS that will fit. 

Apparently you have to use the Mopar 05-06 master/slave. I suspect the slave has a different travel length. 

 

He makes no mention of drive shafts, the 6 speed looks longer,  you may lose your front and rear DS. 

 

As I suspected, the shift tower is not in the same position, you will lose your console, if you have one, you'll have to modify your tunnel, regardless. 

 

I found them on Ebay for around $900, assuming you get one complete, parts are expensive, poster is correct, shift towers are $700 to $1000 depending on part number. Go to Quadratech and look at part pricing, bell is over $1000. 

 

 

New clutch, new slave/master, CPS, wiring connectors.........etc.......possibly new DSs.......this is a minimum $2000 swap. Trans mount alone is $85 and surely you will have to modify your x-member. You'll possibly have to modify your TC linkage or go cable.......if cable, add another $170.

And, you have to believe that you can make it work. 

 

Parts are NOT plentiful, I found a thread where a Mopar dealer had posted Chrysler delivery totals year to year, there was something like 91 6 speeds ordered in 2012.

One of the articles I posted stated what I already knew, new trucks are not even being offered with manuals, future factory support will soon dwindle. 

 

 

My comment about your 'buddy'- When my last trans went out I planned on having it rebuilt, there is not a competent Jeep manual rebuilder near me, Charlotte, Nashville, or Atlanta, those were/are my options. Finding a good manual shop is becoming more and more difficult. 

 

 

 

http://www.wranglerforum.com/f19/6-speed-nsg-370-a-31284.html

Do not purchase a harmonic balance or even call the guys that make these for advice. They did not help me, but only made things confusing. USE YOUR EXISTING FLYWHEEL!!! Do not buy another one. It is not necessary! Don't worry about the position being different on the new transmission. The crank position sensor just tells the engine that a piston is at top dead center and is used to time the spark plug firing. You have six pistons, so it doesn't matter which one is in the TDC position. The only trick is getting the 3 CPS wires correctly connected. They are not in the same order as the old ones. You will need to test them 123, 132, 213, 231, 312 and 321. I think the middle wire was left the same position. One of those 6 combinations is correct and your Jeep will start. The others will not work and your Jeep will not start. It is easy to diagnose. Remove the wires from the old plastic connector housing. You can remove the metal clips from the housing with a special tool or something sharp. I suggest buying some tools for crimping and working with wire connectors (search: pin extractor tool). You can purchase these from Circuit Specialists, Inc, DigiKey Corporation - Electronic Components Distributor or Mouser Electronics - Electronic Components Distributor 


Here is the bill of materials (BOM):

I found the wiring part numbers form another poster and purchased them. In the end, I used the Mercedesmetal pin connectors and removed from wire that they were attached to. Note: removing the crimped-on metal pins from the wires was really difficult, but I only found them sold with short wires attached. I used a 2 sets of small pliers to bend the crimps open. The Mercedes pins, clips or metal connectors (whatever you'd like to call them) were then crimped onto my Jeep's existing wires. This allowed me to put the new plastic housings (to make a complete electrical connector) without any goofy splices. This will keep your Jeep reliable and is really important to do correctly.

Google the part numbers. The Mopar ones can be found on eBay.

Mercedes short wire connectors (pins): 000-540-38-05 get 5

Mercedes connector housing (bushing) for reverse switch: 168-545-27-28 get 1

MOPAR connector housing 3 –wire pigtail for crank position sensor - CPS (same as the speedometer connector): 50-14-007AB $40.97

MOPAR Crank Position Sensor (bolts to transmission bell housing): 04727451AA

Transmission mount bolts 10mm x 1.50 x 30mm – get 4 from Lowes or McMaster Carr

2005-2006 center console – get 1 from eBay or existing console

Clutch slave cylinder: 2005-2006 Jeep master and slave cylinders (sold already assembled)

My NSG370 transmission was missing the small rubber boot on the shifter. Mopar sells the shift tower with the boot only. It is $700, so I used a CV dust boot and later found one on eBay.

Shifter Lever from NSG370

Interior shifter boot - 2005-2006 Jeep: you will need to modify/cut off flange on bottom and drill some new holes in transmission tunnel. You could modify your old steel plate that bolts to the transmission tunnel, but it is a pain.

Transmission Specs for comparison

AX-5
3.93/2.33/1.45/1.00/0.85 with 4.74 reverse

AX-15
3.83/2.33/1.44/1.00/0.79 with 4.22 reverse

NV3550
4.04/2.33/1.38/1.00/0.78 with 3.75 reverse

NSG370
4.46/2.61/1.72/1.25/1.00/0.84 with 4.06 reverse

 

[Jeep Driver]

BTW, you are not just getting a taller OD, 1-4 are considerably shorter............if you can live with that. 

[HOrnbrod]

Another option for knocking down your final drive ratio when highway driving and you can keep the existing NV3550 5-speed. I had a Volvo with a Laycock overdrive unit back in the day that did this - really cut down the RPMs and noise at speed. 

 

https://www.gearvendors.com/testimonials.html

[Eagle]

13 hours ago, johnj92131 said:

 

In 1964 when the 232 was introduced, the factory offered a 3 speed plus overdrive transmission as an option for the high mpg crowd.  The overdrive offered a 30% (or so) reduction in engine speed on the highway.  So idea of slowing the engine down at higher road speeds is nothing new.  Overdrive units go back to the late 20's and 30's.

 

Remember the O.P. wants to reduce engine noise caused by higher than needed engine speed.  The easy way to cut down noise is not to make it in the first place!!

 

Yes, AMC offered an overdrive at the time. As someone whose family owned and drove nothing other than AMC cars, and who hung around with the service manager from one dealership and the son of the owner of another dealership, I can honestly say that I've only seen ONE AMC car with a factory overdrive. That was my mother's 1964 Rambler station wagon. They offered it, but they didn't sell a lot of them. Well under 10% of the number of vehicles sold, and I'd guess it was actually more like less than 1%. They certainly didn't design the engine around the notion that all (or even most) customers were going to have the overdrive.

 

The overdrive wasn't a transmission, it was a separate overdrive unit that mounted after the transmission.

[omega_rugal]

15 hours ago, johnj92131 said:

Your current final drive ratio  with the NP3550 and the 4.10 rear end is:  .78 x 4.10 = 3.198

 

Your current final drive ratio with the 6 speed and the 4.10 rear end is:   .83 x 4.10 = 3.403

 

Regear your NP3550 for a .73 5th with your 4.10 rear end and you get this:  .73 x 4.10 = 2.993

 

Just for reference - You started with an NP 3550 and a 3.07 rear end:  .78 x 3.07 = 2.395

 

And if you keep the current NP3500 and change the rear end to 3.73:  .78 x 3.73 = 2.909

 

Notice the 2 combinations in bold print?

 

i hope he did notice that, even being a six speed with 2 overdrive gears, the 6th is only 0.83, the NP3550 has only five but with a lower final ratio at 0.78

 

early aw4s had a 0.70 OD...you may as well go that route...

 

or use a 3.55 rear axle, just get it from any auto XJ and be done...