Overdrive

[derf]

So I'm looking at what I can do with my project vehicle, a 1985 Grand Wagoneer. My goal is to have it for a daily driver and tow vehicle for a trail rig. I have an idea but I want to know what people think before I really start to dig into it. My goal is to up the gear ratio in the axles without taking a big hit in the top end. The way I figure to do this is by putting in some kind of overdrive.

I have read that Chrysler made an overdrive version of the TF727. Is it feesable to swap in this overdrive tranny in place of the 727 that's in my waggy now? Would I have to do anything special to make it work? i.e. swapping out a GM TH400 and putting in a 4L80E requires adding an aftermarket computer control module.

Another alternative I see is that I can add an aftermarket overdrive module that attaches somewhere in the drivetrain. (models vary exactly where they get placed) Does anyone use one of these and if so, what do you think?

Thanks in advance

[Veepster]

my question is.....Why? what are you trying to accomplish with this change.....

[francis higgins]

I think you can get an o/d unit (from MileMarker?) for the QT units. I don't believe you can get one for the Selec-Trac units though. An overdrive would definitely give you more flexibility with gears and potentially longer life expectancy of the engine. Mileage probably wouldn't go up more than about 1 mpg unless you had very low axle gearing. This has been discussed extensively here, but I don't think anyone has done it yet. I think it has been verified that the early 4.0 overdrive (from a pre 1995 Grand Cherokee) will bolt up if you can find a hydraulically operated one (42rh). This tranny should be able to be built strong enough to handle the V-8. We just need somebody to do it and prove it can be done. :D

[derf]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Veepster:
my question is.....Why? what are you trying to accomplish with this change.....<HR></BLOCKQUOTE>

I want to up the gear ratio to give me better towing capabilities. I need to double check but I think I have the 2.73 gears. That's not good for towing.

Since I won't be towing all the time, I want a way to offset the gear change when I don't need that extra torque. An overdrive would accomplish this.

But if you have a better idea, I'm all ears. I haven't started anything under the hood yet so I'm still open to options.

[Veepster]

gotcha!

why not just make a gear change? and Yes! OD would be really cool....heck imagine a Gear Vendor unit in an FSJ! but the expense I think would more than offset any benefit you would get(I think they are about $3000).......I have 33's and 3.56 gears and love it!...great for towing and normal cruising....not the optimum choice for either worlds but a really nice balance.....

[Snakeyes_Tx]

The overdrive Chrysler 727 you're referring to is the 518A. This transmission wont work for two reasons :

* Bellhousing is not for AMC nor share the 727's pattern for the AMC

* Tailhousing for the overdrive wont fit in the tail end of the AMC 727's case.

You're right on the money with the 4L80E thing needing a computer. You forgot about the 700R4 though. (Not to be confused with the computer controlled version known as the 4L60E). The 700R4 only requires ONE wire that splices into the brake/tail light wire. When the brakes are applied, voltage is carried through the wire to the taillights. The splice will take some of the voltage to kick off the overdrive. Problem being with this is :

* 700R4 is nowhere close to the AMC pattern.

* You'll need expensive adapters for the engine side AND the transfer-case side (or)

* You'll need Engine adapter *and* you'll need the input gear off of a Chevy version of the 208/207/231/241C cases to put in your AMC version of the 208/219/228/229 to match spline counts with the transmissions tailshaft.

My rig was a tow rig to it's previous owner with 2.72's with stock drivetrain with a tranny cooler. Runs like a million bucks now that I have retired the Wag from the "towing" role. To make the OD beneficial, you should upgrade to 4.10's or 4.56's but then you'll probably want a little bigger tire to so you can lower the gearing a bit. With 4.10 or 4.56's with OD and street tires, you'll be running the same RPM range as with what you have right now.

Willypete and I have been calling transmission places all over our cities trying to get answers. Here's what they told us about the 42RH.

* Wont hold up to V-8 Power. BUT, I beg to differ. The 360 on the average in the 80's applications only have 175 hp, and 285 ft/lbs of torque, the 4.0 Liter, which the 42RH is most commonly bolted to, has 185 hp and 220 ft/lbs of torque. I think that the transmission should MORE than hold up to this, with perhaps better clutches, and bands only.

I still think the 42RH is the best choice. Anyone have a picture of what a 42RH looks like compared to a 42RE so we can see the obvious differences when looking for one? I'd like to get my swap underway soon.

Hope this was helpful to you.

[francis higgins]

Snakeyes_TX -

Are you planning on doing the 42rh? Ask if the guts from the 47rh can be swapped into it. Actually, I think the only difference is the number of clutch packs (not sure). I'm sure most tranny places aren't interested in one-off builds. If it is possible though, the stuff should all be available to do it.

[Snakeyes_Tx]

I just cruised the ORC tech pages. In the Jeep section, they didn't list the 42RH in there, it only came up under Dodge Dakota's having the 42RH and the 46RH's.

The 46RH is also listed in the ORC Jeep section, but for 93-95 Grand Cherokee's with 318's.

Are they just missing the 42RH for 4.0 liters?

[derf]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Snakeyes_Tx:
The overdrive Chrysler 727 you're referring to is the 518A. This transmission wont work for two reasons : <HR></BLOCKQUOTE>

Rats. I was thinking that was going to be the answer.

I have read about an overdrive unit that installs after the t-case and has a lockout so it doesn't engage when you're in 4WD. The ones I see only have about a 0.80:1 ratio instead of the 0.69:1 in the 518A. But if I step down from 4.10's to 3.73's, the overdrive ratio comes pretty close.

Here's what I have worked out for final drive ratios:

<UL TYPE=SQUARE><LI>factory 727 with 2.73 gears: 1) 6.69 2) 3.96 3) 2.73
<LI>518A with 4.10 gears: 1) 10.05 2) 5.95 3) 4.10 OD) 2.83
<LI>727 with 0.80:1 overdrive kit and 3.73 gears: 1) 9.14 2) 5.41 3) 3.73 OD) 2.98
[/list]

The second and third option give me pretty close to the original final drive ratio (less than 10% difference) while giving me the bottom end gear adjustment I need for towing duty. When I'm towing, I'll probably leave it out of overdrive but when I'm not towing, I'll be able to get the benefits of lower RPM at speed.

Anyway, that's the theory I'm going on for now. I just have to figure out what I can make work. Since the 518A is out, I'll probably end up doing something about the add-on overdrive kit.

[Snakeyes_Tx]

I haven't been able to find a bolt-on overdrive for our AMC Jeeps. The bolt on overdrives I have seen run somewhere between 1500-2500 bucks!

You might be better off with the 42RH beefed up. I'm still looking for a picture of one.

[derf]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Snakeyes_Tx:
I haven't been able to find a bolt-on overdrive for our AMC Jeeps. The bolt on overdrives I have seen run somewhere between 1500-2500 bucks!

You might be better off with the 42RH beefed up. I'm still looking for a picture of one.<HR></BLOCKQUOTE>

Hell, at this rate, I might as well get a crate GM 350 with a 4L60E... :rolleyes:

Seriously though, there's quite a few people in my 4x4 club who have the tools and skills to fabricate just about anything. I'm going to run a few things by them before I give up.

[Snakeyes_Tx]

Whoa! You're in Tx4x4 too! Ask Mark Claus or Mike Pickel! smile.gif Duh! I shoulda read your signiture a little closer.

[derf]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Snakeyes_Tx:
Whoa! You're in Tx4x4 too! Ask Mark Claus or Mike Pickel! smile.gif Duh! I shoulda read your signiture a little closer.<HR></BLOCKQUOTE>

Well, I just changed it last week or so. If you've looked at it before, it wouldn't be different enough to notice the change.

One other idea I have rattling around in my noggin is the possibility of going to a standard tranny. Would the NV4500 (is that the right number?) fit? I know some wagoneers had standards over the years but how hard would a conversion be? Harder than adapting an overdrive tranny or adding a separate overdrive unit?

Man, I can get myself in trouble if I think too much...

[82wagonlimtd]

OK, I might be off here, BUT if you had a 360/th400 setup, you could bolt in a 700R4 being that they have the same bolt pattern as a th400, SO, all you have to consider is the T-case, but shouldn't that do bolt up or is the rear of a 700R different??

Andy

[derf]

Well, I have an '85 so my tranny is the TF727 unit.

But that does raise a question. Can I retrofit a TH400 or compatible to my block? Is the bolt pattern the same for the blocks used for the TH400 and the TF727? What about the other parts? If that's feesable, can I put a 4L80E in where I would put the TH400?

Hmmm... I'm going to cruise on over to Jet Performance and Advanced Adapters. I'll report the results...

[derf]

Ok, Jet doesn't have much information but Advance Adapters does:

They have a PDF file (http://www.advanceadapters.com/acrobat/bellchart.pdf) that lists an adapter on page 17 to fit in a TH350, TH400 and 700R4 to the stock AMC V8's.

Looks like a 700R4 might be in my future. :D I just have to do some measuring and budgeting.

[Snakeyes_Tx]

No no no no NO! The TH400 used in FSJ's have an AMC specific bolt pattern. There is NO exception to this other than the adapter ring used in 69-72 for the Buick 350 which gave the AMC patterened TH400's the ability to bolt to a Buick, Olds, Pontiac bolt-patterned engine.

The TF727 has the same bolt-pattern as the TH400's that FSJ's used. Theoretically, you could get the adapter ring from 69-72 and bolt in a Buick 455. Brad Feick is doing that, but that doesn't do squat for your overdrive.

Remember, you'll need a 4-600 dollar engine to transmission adapter from AA, or Novak. Also, you'll need the input gear off a chevy 208 so the tailshaft splines of the transmission match the input splines of the T-case.

[derf]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Snakeyes_Tx:
Remember, you'll need a 4-600 dollar engine to transmission adapter from AA, or Novak. Also, you'll need the input gear off a chevy 208 so the tailshaft splines of the transmission match the input splines of the T-case.<HR></BLOCKQUOTE>

Advance Adapters has a part (#716138) which "...was designed to allow the use of a GM TH350, TH400, or 700R transmission to the stock AMC straight 6 cylinder & V8s." They also have a variety of flex plates depending on what kind of motor you have. I'm going to dig into it a little more and see how things measure up. I'll report the results.

I'm more than likely going to do this over the next year or two (need to get into a house before I start pulling the motor) but I will post information I find and pictures of the swap as it progresses.

[Iron Horse]

AA part #716138 is $300.52 and the other part you need for a AMC 360 is p/n 716138c is $61.47 ~ looked em up last night.

I really don't call that a bad price for being abble to hook up an overdrive tranny.

Of course then ya need to think of the transfer case too.

BTW looks like the way to go would be the 4L60 varriation of the 700R~ it's got a 30% overdrive. All of this info is avail. on Advanced Adapters website.

Andy

[derf]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Iron Horse:
AA part #716138 is $300.52 and the other part you need for a AMC 360 is p/n 716138c is $61.47 ~ looked em up last night.

I really don't call that a bad price for being abble to hook up an overdrive tranny.

Of course then ya need to think of the transfer case too.<HR></BLOCKQUOTE>

Thanks for the info. While the swap project is still in the preliminary planning phases, it's good to get as much info ahead of time as I can

<BLOCKQUOTE>quote:</font><HR>BTW looks like the way to go would be the 4L60 varriation of the 700R~ it's got a 30% overdrive. All of this info is avail. on Advanced Adapters website.

Andy<HR></BLOCKQUOTE>

If I'm not mistaken, and please correct me if I'm wrong, but I though the 4L60E was just a computer controlled 700R4, while the 700R4 is an overdrive version of the TH350. If that's the case, I would think the 700R4 would be the better choice. I wouldn't have to get an aftermarket computer to run the tranny.

[Snakeyes_Tx]

Exactly! If you wanted to waste the time hooking up a computer, you might as well for with the 4L80E, which is a TH400 variant.

As for the transfer-case gear... like I mentioned before.. you'll need the input gear from a 208C (for Chevy) to match the tailshaft spline count.

[derf]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Snakeyes_Tx:
Exactly! If you wanted to waste the time hooking up a computer, you might as well for with the 4L80E, which is a TH400 variant.<HR></BLOCKQUOTE>

AFIK, Jet only makes a computer for the 4L80E but not the 4L60E. So that makes yet another strike against the 60...

<BLOCKQUOTE>quote:</font><HR>As for the transfer-case gear... like I mentioned before.. you'll need the input gear from a 208C (for Chevy) to match the tailshaft spline count.<HR></BLOCKQUOTE>

How much would something like that cost? And how difficult is it to install?

[Snakeyes_Tx]

Couldn't tell ya, I've never done one. I imagine you zap the 6 bolts off the input side of the case and it slides out.

You can use any of these GM X-case input gears : 207, 208, 231, 241, 242... all will be followed by the letter code "C" ex. 207C, 208C, 231C.. you get the idea.

[82wagonlimtd]

SO all I need is the 2 AA part numbers and a input gear I can find at a junkyard and I can have OD??????

Andy

[derf]

<BLOCKQUOTE>quote:</font><HR>Originally posted by 82wagonlimtd:
SO all I need is the 2 AA part numbers and a input gear I can find at a junkyard and I can have OD??????

Andy<HR></BLOCKQUOTE>

You need the adapter, the input shaft for the t-case and an overdrive transmission (a 700R4 is a good choice). Depending on how things fit, you may need to relocate the t-case which means new driveshafts. I'm estimating a minimum of $5,000 if I can find good deals on parts.

BTW, I've already found an input shaft out of an NP208. I was wheeling with a guy about a month or two ago. He has an 81 Chevy K20 long bed. I went up a hill in my XJ and cleared a rock. His lower breakover angle combined with no skid plate and a little too much momentum caused him to bounce up and land his t-case on that rock. :eek: Shattered the case but all the gears and shafts were fine. Since I flat-towed him home with my XJ (he wanted to use his wife's car) he's willing to give me the input shaft from his 208C for nothing. :D

One down, several to go. :cool:

[Snakeyes_Tx]

Ooh.. left that little tidbit out actually, thanks Derf for bringing it up.

You will definitely need to have a front driveshaft made up. The 700R4 is quite a bit longer than the 727 or TH400. Id say a good 6 inches longer if not more. Basically, your front driveshaft is going to look about the same length as your newly shortened rear one. I've been toying with the idea of using a carrier bearing on the front to alleviate one BIG angle down into two smaller ones.

You can use the original T-case crossmember, just slide it back and drill new holes. You may need to notch it depending on your amount of lift and the angle of that longer shaft.

Correct me if I'm mistaken, but when you do the AA adapter thing.. don't you also need an adapter flexplate too? It's quite a bit thicker to help compensate the adapter's length and also matches bolt pattern of crank on one side, and torque converter on the other?

Might wanna ask them about this.

[ August 27, 2001: Message edited by: Snakeyes_Tx ]

[derf]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Snakeyes_Tx:
You can use the original T-case crossmember, just slide it back and drill new holes. You may need to notch it depending on your amount of lift and the angle of that longer shaft.

Correct me if I'm mistaken, but when you do the AA adapter thing.. don't you also need an adapter flexplate too? It's quite a bit thicker to help compensate the adapter's length and also matches bolt pattern of crank on one side, and torque converter on the other?

Might wanna ask them about this.

[ August 27, 2001: Message edited by: Snakeyes_Tx ]<HR></BLOCKQUOTE>

No lift for me since it's a tow vehicle. What are the chances of needing to notch the crossmember? Also, is the rear driveshaft a slip yoke design or fixed at each end with a slip joint in the middle? Either way, won't I need to shorten it if the tcase moves?

Oh, and the second part listed by Iron Horse was the flex plate that goes with the adapter (if I'm not mistaken). They are listed together in the catalog.

[Iron Horse]

Hi guys, back from the weekend.

When I said "it looks like the 4L60 would be the better choice....", I got that info from the AA site. I could swear that they were talking about a non "E" 4L60. Here is the particular page 700R/4L60 (http://www.advanceadapters.com/acrobat/gtrans.pdf)

It looks like they are saying the 4L60 is a refined 700R "....name changed in 90's to 4L60"

Scroll down the page for 700R

Andy H.

[ August 27, 2001: Message edited by: Iron Horse ]

[Barrys]

Not sure if you ever thought of this but I have read it in many Magazines and it sounds right.
If you change gears and lower your MPG, you use more fuel. Think about how much fuel you could buy with the money the swap will cost. One magazine said you would have to drive over 100,000 miles to recoup the cost of swapping in the O/D(in their hypothetical swap). It would be cool to have but $$$ it almost doesn't make sense in MOST cases, yours may be different. I'm not trying to come across as an Great Googley MoogleyGreat Googley MoogleyGreat Googley Moogley so please don't take it that way smile.gif

[Barrys]

Not sure if you ever thought of this but I have read it in many Magazines and it sounds right.
If you change gears and lower your MPG, you use more fuel. Think about how much fuel you could buy with the money the swap will cost. One magazine said you would have to drive over 100,000 miles to recoup the cost of swapping in the O/D(in their hypothetical swap). It would be cool to have but $$$ it almost doesn't make sense in MOST cases, yours may be different. I'm not trying to come across as an Great Googley MoogleyGreat Googley MoogleyGreat Googley Moogley so please don't take it that way smile.gif

[derf]

My intention is not to improve mileage. What I want to do is up the gears for towing without affecting the top end RPM too much. The net effect of upping gears and adding an overdrive is that I end up with a granny gear and a final drive ratio that is within 5% of original. Doing just the gears would put my RPMS above 3,500 at 65 MPH. That's hard on any engine.

Besides, this is not about recouping an investment. It's about building a Jeep the way I like it. :D

[Barrys]

If you want a granny gear and strong I would say go with a NV4500, a 5 speed isn't as nice a an auto for towing big it has a granny gear and od and is way strong.
Jet performance has what they call a turbo700. It's a 700r4 beefied way up. It doesn't have the low 1st gear like the NV4500 but with the torque converter, it should be noticabley lower than what you have now. I am pretty sure it can bolt in just alike a th350, no computers or crap. It's not cheap, toss that behind a BBC crate engine, and an Atlas t-case and you got a sweet (expensive) setup. or to save 2k, use a NP205, no expensive adapters(assuming front drop is on the right side. Sell you current stuff to recoup some money. We all know Chevy parts are cheaper to buy the AMC stuff. You SHOULD do this so we know what is needed in putting a SBC or BBC in a FSJ. Has anybody on here put a chevy engine in a FSJ?

[derf]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Barrys:
If you want a granny gear and strong I would say go with a NV4500, a 5 speed isn't as nice a an auto for towing big it has a granny gear and od and is way strong.
Jet performance has what they call a turbo700. It's a 700r4 beefied way up. It doesn't have the low 1st gear like the NV4500 but with the torque converter, it should be noticabley lower than what you have now. I am pretty sure it can bolt in just alike a th350, no computers or crap. It's not cheap, toss that behind a BBC crate engine, and an Atlas t-case and you got a sweet (expensive) setup. or to save 2k, use a NP205, no expensive adapters(assuming front drop is on the right side. Sell you current stuff to recoup some money. We all know Chevy parts are cheaper to buy the AMC stuff. You SHOULD do this so we know what is needed in putting a SBC or BBC in a FSJ. Has anybody on here put a chevy engine in a FSJ?<HR></BLOCKQUOTE>

This whole thread has basically been about how to fit that 700R4 with the AMC motor. That is, once it was decided that the 700R4 was the tranny to use.

I thought about the NV4500 but decided converting to a standard would be more effort than I was willing to sink in. Not only would I have to fit the tranny (move the t-case, swap drive shafts) but I would have to set up a clutch pedal. With the automatic, all I would have to do is the tranny.

With the TF727 and 2.73 gears, first gear final drive ratio is 6.77:1 and high gear is 2.73:1. With the 700R4 and 4.10 gears, low gear is 12:55:1 and high gear is 2.87:1. That translates to just a 0.05% increase in RPMs at highway speed but almost a 2:1 increase off the line. Perfect for towing I'd say.

To top it off, I can get a lockup converter for the 700R4. That will probably end up reducing the effective RPMs at speed over the current TF727 and drastically reduce wear when I'm towing. And that's not a bad thing.

Since this rig is only going to be a tow vehicle/daily driver, I'm not too worried about the t-case. That's a hassle and expense I don't want to bother with. Besides, I already have the input shaft from the NP208C so I don't have to worry about adapting the tranny to the t-case.

I will be taking pictures of all this and do my best to document it. Even if it's not exactly the same kind of swap you would do, I would bet you'd find some usefull information from the writeup.

[Bucky]

Iron Horse is correct in that there are two versions of the "60" tranny. Me thinks that in 90 1/2 they added clutch packs to the 700R4 and renamed it. I think that the "E" came about in 93/94. To ask the experts go to www.s10-4x4.com (http://www.s10-4x4.com)
those guys know tons about the 700R4 and its derivitaves.
Bucky