Transmission questions

[Art Welch]

At Pismo a few months ago w/ Bruce and Robert it hit me that I really want more horsepower and while I'm at it want an auto so I can actually make use of it. The conversion that Bruce did is cool w/ a reverse pattern manual valvebody and would be the best of both worlds I think. While searching the web I ran across this:

http://4wheeloffroad.com/techarticles/131_0302_TRAN/

Any thoughts on this approach? Is the 700r4 a reasonable choice for a fairly high horsepower application (400+)? I've read a few stories about it being a difficult swap but all seemed to be related to mating to an existing jeep drivetrain. Torque converter recommendations?

I've read the threads like this one (http://www.jeepbbs.net/forums/showth...&threadid=5608) but given the horsepower issue don't know to what degree the choices others have made are right in this situation. The other thing is that I want this to perform very well in the rocks but also let me use all the power efficiently in the sand and mud.

Thanks for any help, I'm starting from ground zero with knowledge in this area.

[mrblaine]

Originally posted by Art Welch
At Pismo a few months ago w/ Bruce and Robert it hit me that I really want more horsepower and while I'm at it want an auto so I can actually make use of it. The conversion that Bruce did is cool w/ a reverse pattern manual valvebody and would be the best of both worlds I think. While searching the web I ran across this:

http://4wheeloffroad.com/techarticles/131_0302_TRAN/

Any thoughts on this approach? Is the 700r4 a reasonable choice for a fairly high horsepower application (400+)? I've read a few stories about it being a difficult swap but all seemed to be related to mating to an existing jeep drivetrain. Torque converter recommendations?

I've read the threads like this one (http://www.jeepbbs.net/forums/showth...&threadid=5608) but given the horsepower issue don't know to what degree the choices others have made are right in this situation. The other thing is that I want this to perform very well in the rocks but also let me use all the power efficiently in the sand and mud.

Thanks for any help, I'm starting from ground zero with knowledge in this area.

I've seen similar arrangements and always wondered why go to an auto if you have to shift it yourself? It is also easy to damage the tranny if you have a distraction and attempt to take off in D with high horsepower.

Put it in D, it takes off in drive. Bad things happen.

[TObject]

400 HP! Are you putting a Corvette engine in it?

[Art Welch]

I've seen similar arrangements and always wondered why go to an auto if you have to shift it yourself?

The main thing I'm trying to do is reduce the time it takes to shift, with a manual by the time I shift on a steep or loose hillclimb I've lost most of the momentum.

It is also easy to damage the tranny if you have a distraction and attempt to take off in D with high horsepower.

I agree it would take a bit of extra attention, my thought was that the reverse pattern would be a help here.

400 HP! Are you putting a Corvette engine in it?

I am.

[mrblaine]

Art, wannabe auto owners that make every attempt to retain manual tranny characteristics, like having to shift, hitting the wrong gear, always baffle me. If you like the manual and it's traits so much, keep it.

If you want to go auto, get an auto that does what an auto does best. Shift automatically. That's why they call them autos.

If you want to get a manual that can be shifted faster, get a Lenco.

Just take the auto, put a firm not harsh shift kit in it, beef up the components that are known to fail, and go enjoy learning how to drive with two feet.

Consider that you may be doing a bonsai up a hill and hit a bump while going from first to second and wind up in 3rd with full throttle on 400 ponies under the hood? Is that what you really want?

[Art Welch]

All fair points.

If I go that route what is the best way to deal with the frustrations I've had with auto trannys in the past (like the one in my truck right now), specifically:

1. Having to rev the heck out of the engine to bump up a ledge. You'll laugh but the main thing I like about my current setup is that I can crawl up anything that provides traction without revving the engine and get to the top without any excess momentum at exactly the speed I want. I realize the torque converter in my truck is not a good comparison but what is the right thing to look for to meet my off road objectives?

2. Crappy compression braking. Robert mentioned that he had dealt with this and now has compression braking as good as a manual, just not sure how to achieve this.

3. Excessive downshifting. The thing that really bugs me in the truck is that given just a little extra throttle on a hill it immediately jumps down two gears and I go from efficiently torquing along at 1700 rpm to 2800 rpm.

I realize these are basic questions but like I said I'm new to the auto tranny thing.

[Bruce David]

http://artcarr.com/

No missed shifts with one of these shifters.

Seeing how our jeeps have evolved to weekend warrior
status, shifting is a non-issue.

If I had a DD I would be inclined to put the stock vale body back on.

But what do I know, I still have flat springs.

[TObject]

How much does one of those dune buggies cost?

Maybe it would be better to leave the jeep for rock crawling, and build a separate vehicle for blasting through dunes.

I don't know for everybody else, but when I am wheeling, my jeep automatic shifter is mostly in 1st gear all the time, except when I am parked, or going in reverse.

[TObject]

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[Art Welch]

It would be alot of fun but I wouldn't trust myself in one of those Sergey, when I was younger I rode dirt bikes and got into trouble more than a few times launching off bigger jumps than I should have, even though I'm older now I don't think my impulse control for that stuff has gotten much better! I'll live longer sticking with vehicles that stay mostly on the ground.

[Robert J. Yates]

art - the one thing you will notice with us is that we are driving 2 footing our rigs - one on the gas and the other on the brake. that tends to take care of the over rev issue very handily. I am pretty much using the brake to modulate forward prograss on the big obstacles.

[Art Welch]

Hey Robert - what did you do to the tranny get your compression braking? I think you said it is as good as a manual, that is really key for me, to make the move I really want to have a robust solution. I've read about valvebody mods that provide it?

On the torque converter I read that there are some that lockup at 1000-1100 rpm, I guess that is a solution to the rev it up problem? Or are there related problems with that making it not a good idea? Mine doesn't see much road use (2500 miles in the last 3 years) and will probably see even less moving forward.

[TObject]

If your main brakes work fine, why do you care how good your compression braking is? Just wondering, not saying it's wrong.

You say that compression braking is a key point.

[Paradiddle]

Art,

My TJ auto is stock and my t-case is stock. I've got 4.56 with 35" tires.

I can compression brake down what I call steep hills in first and 4-lo and never touch the brake.

I think the whole "autos don't compression brake" comes from people who are either used to a super deep granny first on their stick, or are geared wrong with too big of tires.

I'm curious, if you are putting a big horse engine in for blasting why are you concerned about compression braking?

I would second Sergey's recommendation to get a sand toy with a full cage - your Jeep will thank you later when you don't bend it in half

Jeff

[Art Welch]

The compression braking thing for me is static vs dynamic coefficient of friction. I like to climb and descend steep hills (I just like heights I guess and really steep hills are fun) and when usings brakes to descend invariably I lock em up and gravity takes over, when rolling along letting the engine slow me down all is good. The reason I'm concerned about this with a high HP setup is that I only want to own one jeep and I like to do alot of different things with it, the HP helps you up, the compression helps you down.

I don't buy that autos don't compression brake because I've heard from enough people that I've known for a few years now that they do fine at it, I just want to know what specifically it is that I need to do to ensure that mine does.

A sand toy would be fun but I don't have anyplace to put it and I really like my jeep and think it can do both. Plus blasting through the mud with a bunch of power is a heck of a lot of fun (although the cleanup isn't) and a sand toy won't do much with that.

I get the sense that some may think I'm asking about this stuff in a less than sincere way to provoke the old auto vs manual debate. Not the case, that debate is pointless and frankly I don't give a rip what anyone else drives, I just hope they are happy with it. I'm going with an auto with the new engine and any help is appreciated but regardless I'm sure I'll figure it out eventually with trial and error.

[Art Welch]

I don't give a rip what anyone else drives

Re-reading my post this isn't an accurate statement, I'd like to learn from what other people drive. I have no interest in convincing them that they shouldn't be driving an auto (or whatever).

[Paradiddle]

Originally posted by Art Welch
I get the sense that some may think I'm asking about this stuff in a less than sincere way to provoke the old auto vs manual debate. Not the case, that debate is pointless and frankly I don't give a rip what anyone else drives, I just hope they are happy with it. I'm going with an auto with the new engine and any help is appreciated but regardless I'm sure I'll figure it out eventually with trial and error.

Not my thought at all - I was just curious. I kinda forgot that if you blast up you gotta go down!

I think the 700R4 has a pretty deep first gear so I would think compression braking would be better then a stock TJ tranny. I'm sure your pumpkins are geared for your tires so you should be good to go.

The only reason I suggested the sand buggy is so you bend/break your TJ in half! That would suck.

Jeff

Oh - and PS - Ron Schneider had one of those manual auto's in his rock crawling comp rig - I saw it mess him up once during a competition - seemed his was fiddle farting around with shifting.

I realize you aren't competiing, but I try to go with the KISS principle.

[Jeff Weston]

Art,

My dad had his AX-15 in his YJ swapped out for a 700R4. He chose it not for its overdrive, lower first gear or increased strength, but rather to clear his Atlas I transfercase that cannot clear the 32RH.

Like you mentioned, some of the difficulties in the swap were due to the fact that he was mating it up to a stock driveline (two adaptors and cps relocation). It ended up costing a ton of dough, time and frustration but it does work well. One thing I don't really like is the Art Carr shifter he has which is what everybody seems to use, including the article you mentioned. With the gate design it is difficult to get quickly from 1st to reverse and vice versa.

You may want to talk to the place where he got his transmission, they're supposed to really know what they're doing and did right by my dad.

Bowtie Overdrive in Hesperia:

http://www.bowtieoverdrives.com/index.shtml

You can go directly to the 700R4 info:

http://www.700R4.com

Not only did they build the transmission but they also sold all the parts required to do the swap, including adaptors, CPS relocation, TV cable, etc. I'm sure they could answer a lot of your questions.

Good luck!

[TObject]

Turning your lockers on before going downhill easily solves the locking the individual brakes on descent problem. You have to have manual lockers or spools for that though, this method won't work with Detroits or the like.

[Stu Olson]

Originally posted by TObject
If your main brakes work fine, why do you care how good your compression braking is? Just wondering, not saying it's wrong.

You say that compression braking is a key point.

I can give you a typical example that happened to a friend of mine as we descended the last mile Moab Rim trail. For me, with a 4:1 t-case, 4.56 gears, manual tranny, and 35" tires, I had to give it gas most of the time as we came down. At that time, Mike was running 33" tires, 4.10 gears, and a regular 231 t-case in his '00 TJ w/ an auto. Unfortunately, he discovered he had warped his front brake rotors by the time we reached the bottom.

I am not saying this happens to everyone and I'm not saying we could not have done something to mitigate the problem (but that is another thread).....but that was the way it turned out.

This spring's trip to Moab was done with a 3.8:1 Atlas II and 35" tires and he was very pleased with his down hill performance.

[mrblaine]

Originally posted by Stu Olson
I can give you a typical example that happened to a friend of mine as we descended the last mile Moab Rim trail. For me, with a 4:1 t-case, 4.56 gears, manual tranny, and 35" tires, I had to give it gas most of the time as we came down. At that time, Mike was running 33" tires, 4.10 gears, and a regular 231 t-case in his '00 TJ w/ an auto. Unfortunately, he discovered he had warped his front brake rotors by the time we reached the bottom.

I am not saying this happens to everyone and I'm not saying we could not have done something to mitigate the problem (but that is another thread).....but that was the way it turned out.

This spring's trip to Moab was done with a 3.8:1 Atlas II and 35" tires and he was very pleased with his down hill performance.

Stu, you're confusing me.

First you say you are giving a typical example, then you say you are not saying that it's typical.

[Art Welch]

Originally posted by Jeff Weston
You may want to talk to the place where he got his transmission, they're supposed to really know what they're doing and did right by my dad.

Bowtie Overdrive in Hesperia:

http://www.bowtieoverdrives.com/index.shtml

You can go directly to the 700R4 info:

http://www.700R4.com

Thanks Jeff, excellent info on those pages, I'll give them a call this week.

[Stu Olson]

Originally posted by mrblaine
Stu, you're confusing me.

First you say you are giving a typical example, then you say you are not saying that it's typical.

Sorry...should have clarified that better.....a typical comment by auto owners I have met is that coming down steep hills....they have to ride the brakes. Hence....a typical example....riding the brakes coming down a hill.

I do not believe it is typical for everyone to warp the rotors (but I could be wrong....maybe it is.....I see postings about warped rotors on the forums so they must be getting ruined some how).

[mrblaine]

Originally posted by Stu Olson


I do not believe it is typical for everyone to warp the rotors (but I could be wrong....maybe it is.....I see postings about warped rotors on the forums so they must be getting ruined some how).

I would guess that trailriding is responsible for about 1 percent of the warpage reported. That's being generous.

I would also venture that living in Big Bear and coming down the mountain would be responsible for another 2 percent and import low quality rotors or composite rotors of any persuasion responsible for the other 97 percent.

I've had upgraded higher performance brakes through 3 different axle iterations, 5 different braking systems, and a ton of trail rides and have never warped a rotor. I've even driven them through streams after hauling through the trails around Big Bear and had steam pouring out from the front wheels crossing streams and still never warped a rotor.

Quality rotors are just that, quality and quality doesn't seem to care how you treat it, they just work.

BTW- my old set of WJ rotors is in another rig and still not warped.

I'm gonna play the optima card and state that because mine don't, no one else's should either.

[Art Welch]

Originally posted by TObject
Turning your lockers on before going downhill easily solves the locking the individual brakes on descent problem. You have to have manual lockers or spools for that though, this method won't work with Detroits or the like.

The problem with that is if it is really steep and loose you'll slide anyway unless you can control pedal pressure a heck of alot better than I can, the dynamic to static transition is abrupt and then things get interesting really quickly. Plus based on personal experience descending hills in the mud I can report that engaged lockers are not necessarily an asset unless you want to see the hill from a very interesting sideways perspective.

[speaceman]

How long are these hills you are planning on decending?

I never had any problems with getting out of control in my Zj running a stock t-case, 4.88 and 33s on any of the long hills out at TDS when we've gone.

I let the ZJ engine brake on the hills out there and I never got out of control by the bottom. I generally had enough engine braking to stay within an acceptable and controllable speed as well.

Are you looking to do steeper and longer than that?

On hills steeper than anything out at TDS, i would have to ride the brake, but the hills are generally much shorter, so it never really mattered.

Where are the really steep and really long hills?

[TObject]

If you do want the wheels locking individually, you can do that too with manual lockers, just disengage them. That's a booty of manual lockers: you can turn them on, you can turn them off... I believe I can control brakes better with the brake pedal than with the engine. And my second foot is on the gas, to give it a go immediately in case I start sliding.

The guy with the Atlas, on the other hand, may or may not have enough of the go potential to bring sliding under control right away. I am speculating here, never drove an Atlas.

[Stu Olson]

Had I known I would create all that typing for you, I would have skipped that part of my response that was within the ( ). I'm sure all agree that quality parts provide quality results.

However....my response to Sergey was not so much about rotors warping as it was about compression braking. My comment concerning Mike's rig coming down Moab Rim trail is still valid. He had no where near enough compression braking to prevent the continuous application of his brakes for the 30~45 minutes we take coming down. I included a rotor comment which was obviously not needed.

[John]

Years ago when I lived in Colorado and wheeled up and down extremely steep hills we'd give a couple clicks of the ebrake to help out the auto transmission rigs. Always worked a lot better then stepping on the brake pedal and having the rear try and pass the front.

About the only other thing I can add here is that the 700R4/4L60E trans has a 3.06:1 first vs. the stock Jeep 2.75:1 first.

[Art Welch]

Originally posted by speaceman
On hills steeper than anything out at TDS, i would have to ride the brake, but the hills are generally much shorter, so it never really mattered.

Where are the really steep and really long hills?

The TDS hills with the thick loose soil are okay, on those I usually drive down in second gear under throttle rather than relying on compression braking, that keeps it straight for me. The ones that are more problematic are like the one with the ledge about 2/3 of the way up that nobody in our group has gotten over (right next to the climb that Michael had to winch me out of this year) where the surface is a bit harder and alot slicker. I just really don't like going down stuff like that using brakes, just a little bit sideways can be really ugly.

There are a few other hills like that in the Santa Clarita area, they can be very treachorous with some moisture.