42RLE transmission reprogram/shift kit??

[belvedere]

Thanks...but my whole point in the first place was that they have nearly identical transmissions.

But it's not just the trans, it's the programming, and also the effect of the engine characteristics.

And you've lost me on why an "OHV" engine cannot have the same lift, duration, etc as a SOHC.

It's not that they can't, just that they ususally don't.

I certainly haven't studied all of the specs of the 3.3/3.8 (I don't own one), but I've driven them, and they definitely feel different than the 3.7.

Like tj said, there are many little differences in the two engines. Little differences together can produce a very different end result.

 

[RoyalDudeness]

Dude leaves overdrive off till he hits about fifty and that's on flat surfaces. On that deal; is there any way to reprogram the ride's brain so that overdrive is off at start up? Dude was also told by a performance shop that a plug-in programmer can be used to change shift points and other neat-o characteristics.

 

[J-Thompson]

simple terms
more RPM = more torque
more torque = more up hill power
more gas = more RPM
pedal pushed down = more gas
or
regear to 4.10's and do NOT do any thing to the ecm/tcm's in the way of reprogram
that way the Jeep thinks it has 3.73's but it really has 4.10's
this will make it shift even sooner ,slower speed will = the same rpm as faster speed
with 3.73's but with OD off you will crank out some RPM to go 60mph thus
more rpm = more torque ,see above

 

[tjkj2002]

Thanks...but my whole point in the first place was that they have nearly identical transmissions.

And you've lost me on why an "OHV" engine cannot have the same lift, duration, etc as a SOHC.

If you want to start talking DOHC, then I can agree with you...but that's not what we're talking about here.

SOHC engines are more like DOHC engines.

OHV = Over Head Valve,the cam is inside the block,uses push rods

SOHC = Single Over Head Cam,the cam is located on top of the cylinder head

DOHC = Dual Over Head Cam,has 2 cam located on top of the cylinder head

Which 2 are more closely related? Which one is completely different?

 

[flair1111]

The 42RLE has crap gear ratios,add a lack luster torque curve of the 3.7 = piss poor driveability and prone to overheating.

There is no fix,the "shift kit" for the 42RLE is useless and does not do much,changing the shift points will not help either since you still have crap ratio's.


Long live the '02 KJ's with the 45RFE(woot)

this is the answer! my wifes 02 feels like it has a V8 just off of shift points alone with her trans. my 06 feels like a 4cyl depending on the amount of gas i must give it to get it to shift anywhere near ok. to the OP...its a pain but i have just learned to drive mine while i manual shift it and mess with the OD button. i almost always start in second if i know im gonna be running faster than 40mph. then at 35 i shift to 3rd (D) with OD off, then at 55-60, depending on incline of road, i turn OD on. its a pain and i hate it, but it avoids the crappy shifting and hopefully is easier on the ****** in the long run. a B&G flash is what Im gonna do soon and i hope it helps some, but who knows.

 

[osufans]

SOHC engines are more like DOHC engines.

OHV = Over Head Valve,the cam is inside the block,uses push rods

SOHC = Single Over Head Cam,the cam is located on top of the cylinder head

DOHC = Dual Over Head Cam,has 2 cam located on top of the cylinder head

Which 2 are more closely related? Which one is completely different?

Agreed...however the valves are still on top of the head (usually), it is just the way they are actuated that is the difference.

A DOHC is a different beast altogether, because then you can start tweaking intake timing vs exhaust timing, which from my limited knowledge of mechanics, is darn near impossible with a pushrod motor. And generally a DOHC is employed when you start using more than 2 valves per cylinder, especially so that you CAN use adjustable valve/cam timing.

I will agree that generally, a SOHC motor may have different characteristics than a typical pushrod motor, but that doesn't mean they will always be different. And it definitely doesn't mean that they HAVE to be different.

I was merely basing my judgment off the fact that both engines reach peak TQ at 4K rpms, both engines' peak TQ is around 235-240 ft/lbs, both engines reach peak HP at 5K-5.2K RPM's, and both engines' peak HP is around 210-215HP.

That doesn't mean that their curves are identical, and since I cannot find a dyno sheet for either motor, I won't know for certain...but that was the basis for my comparison.

 

[osufans]

Dude leaves overdrive off till he hits about fifty and that's on flat surfaces. On that deal; is there any way to reprogram the ride's brain so that overdrive is off at start up? Dude was also told by a performance shop that a plug-in programmer can be used to change shift points and other neat-o characteristics.

This is EXACTLY what I'm trying to find out! Thanks!

 

[tjkj2002]

Agreed...however the valves are still on top of the head (usually), it is just the way they are actuated that is the difference.

A DOHC is a different beast altogether, because then you can start tweaking intake timing vs exhaust timing, which from my limited knowledge of mechanics, is darn near impossible with a pushrod motor. And generally a DOHC is employed when you start using more than 2 valves per cylinder, especially so that you CAN use adjustable valve/cam timing.

I will agree that generally, a SOHC motor may have different characteristics than a typical pushrod motor, but that doesn't mean they will always be different. And it definitely doesn't mean that they HAVE to be different.

I was merely basing my judgment off the fact that both engines reach peak TQ at 4K rpms, both engines' peak TQ is around 235-240 ft/lbs, both engines reach peak HP at 5K-5.2K RPM's, and both engines' peak HP is around 210-215HP.

That doesn't mean that their curves are identical, and since I cannot find a dyno sheet for either motor, I won't know for certain...but that was the basis for my comparison.

They will be just due to the differences in the engine design.

OHV -- 2 valves per cylinder,1 intake and 1 exhaust.Cam in block,pushrods activate rocker arms which push the valves open/closed.You can adjust valve lift and duration for both intake/exhuast valves but will be fixed at all rpm's.

SOHC -- 2-4 valves per cylinder,1-2 intake and 1-2 exhaust.Can on top of cylinder head,use a cam followers to open/close valves.You can adjust valve lift and duration for both intake/exhuast valves but will be fixed at all rpm's.

DOHC -- 4-8 valves per cylinder.Cams on top of cylinder head(just like a SOHC) and use cam followers to open/close valves(just like a SOHC).You can adjust valve lift and duration seperatly between the intake and exhuast and can adjust valve duration depending on rpm's(not lift though,that is always fixed).

 

[osufans]

They will be just due to the differences in the engine design.

OHV -- 2 valves per cylinder,1 intake and 1 exhaust.Cam in block,pushrods activate rocker arms which push the valves open/closed.You can adjust valve lift and duration for both intake/exhuast valves but will be fixed at all rpm's.

SOHC -- 2-4 valves per cylinder,1-2 intake and 1-2 exhaust.Can on top of cylinder head,use a cam followers to open/close valves.You can adjust valve lift and duration for both intake/exhuast valves but will be fixed at all rpm's.

DOHC -- 4-8 valves per cylinder.Cams on top of cylinder head(just like a SOHC) and use cam followers to open/close valves(just like a SOHC).You can adjust valve lift and duration seperatly between the intake and exhuast and can adjust valve duration depending on rpm's(not lift though,that is always fixed).

Sorry, we should probably just stop debating the subject since this isn't even related to my question in this post...but...the Dodge Hemi 5.7L is an OHV 4 valve per cylinder pushrod motor.

 

[tjkj2002]

Sorry, we should probably just stop debating the subject since this isn't even related to my question in this post...but...the Dodge Hemi 5.7L is an OHV 4 valve per cylinder pushrod motor.

Well it does have alot to do with how the trans shifts and feels in a 4000lbs brick,but okay.

Just one last thing though..............

The 5.7/6.1/6.4/7.0/7.2/7.4 HEMI's are only a 2 valve per cylinder OHV engine,oh and the new HEMI's are not true HEMI's anymore either(scroll down about 2/3 of the way down in the below link).

You must be registered for see images

http://www.allpar.com/mopar/new-mopar-hemi.html

 

[osufans]

My bad..I misread some information regarding OHV motors, which appeared to say that the Chrysler Hemi used 4v/cyl pushrod configuration. Guess you should double-check before you post....doh!

So back to my original question, is there such a thing as a reprogrammer for these Liberty's?

 

[ridenby]

Just get a torque converter and shift kit from APS Precision, and a flash from B&G, and you're good to go.

KYLiberty gave it to you on page one. (attn)

 

[osufans]

KYLiberty gave it to you on page one. (attn)

Is that the ONLY reprogrammer available? I don't exactly have the ability to pull my PCM and be two weeks without a vehicle.

Also, the shift kit is doable, but I'm definitely not interested in dropping the transmission to install a new torque converter....you all think I have $$$ coming out the yin-yang? lol

 

[ridenby]

Is that the ONLY reprogrammer available? I don't exactly have the ability to pull my PCM and be two weeks without a vehicle.

Also, the shift kit is doable, but I'm definitely not interested in dropping the transmission to install a new torque converter....you all think I have $$$ coming out the yin-yang? lol

Understand money very well,KyL,has looked into this,and what he says about it carries weight,in my world,check his past posts.

 

[osufans]

will do, thanks!

 

[KYLiberty]

Let me expand on my previous short post a little. First, you have the 42RLE, so you're limited in ability to upgrade as well as having a very poorly performing setup.

Good news is that you can improve it enough to drive quite nicely.

The catch is that it is expensive if you're not going to keep the KJ. If you're going to keep it forever like I plan to, and nothing is broken right now, you can plan it out, save for it (dreaming about it while saving of course), and then buy the goodies and install them. (biggringift)

You will want to call and talk to people. Discuss the way you would prefer for it to perform, what size tires you'll be running, gear ratio, if you will be towing, etc. For the torque converter and shift kit call Wayne at APS Precision http://www.apsprecision.com/. He gets very busy at times, but he's really worth waiting for.

My B&G flash was a custom aggressive flash to Marty at KRC Performance's specs and the first they ever did for the 3.7. Since it went through KRC, I don't have a contact at B&G. However, you should call them. They have both engine and transmission reprogramming for you and they are very good.

The nice thing is that you can do each of them 1 at a time, or all at once. If you bring these things together, you can really change the way your KJ drives.\\/

 

[KYLiberty]

You know, you could talk to Wayne about a built transmission.:-k

 

[osufans]

You should just get a man'smission ike the 45RFE.

Not that I'm sure if it's ever been done, or even compatible, but I'd put a 545RFE in before I'd put in a 45RFE!!! lol

yeah, not really wanting to get into it too deep. the only thing i don't like is it wants to shift into O/D AND lockup at about 45 if I'm not heavy on the pedal, which out of habit, i just don't stomp on the pedal all the time, and by the ****** doing that, it drops the RPM's below the torque level needed to maintain my current level of acceleration, which then causes the ****** to downshift. seems kinda pointless.

it sounds like it just needs some tweaking, but if it'll be a one-off, then it won't be cheap. i'll keep looking, but thanks for the suggestions.

 

[KYLiberty]

Talk to B&G about their transmission flash for the 42RLE. It might be an easy way to help out with your problems and I think it's a standard $350.

 

[JeepJeepster]

Talk to B&G about their transmission flash for the 42RLE. It might be an easy way to help out with your problems and I think it's a standard $350.

Since the computer is altogether on most 42rles cant they do everything at the same time? They stopped using separate computers in 2003 sometime.