4x4_Ferg

My 1990 4Runner V6 sometimes has trouble holding speeds over about 70 once it shifts into overdrive on the freeway, even when the road is completely flat. This causes me to have to downshift a lot which is hard on the tranny and uses a lot of gas. Then there are times where it seems to do fine, for a 3.0. I drove to Tucson and back, where the speed limit is 75 most of the way, last weekend, and got so impatient with it that I just turned the OD off for almost the whole trip. Obviously the 3.0 is anything but fast, but there seems to be no reason why it should have trouble holding 70-80 in overdrive, assuming I'm not going uphill of course. It seems like a tranny/ torque converter issue to me. Does anyone else on here with a 3.0 and automatic tranny have this problem? Also, has anyone with this problem found a way to make it cruise better (better torque converter, etc.)?

tc

The automatics are undergeared from the factory due to the MONSTER overdrive. I see you have 33's, but no mention of regearing.

I'm surprised you can hold the overdrive at all. Functionally, your truck is fine.

You need to regear or swap in a 5speed. (Sorry)

LS1Steve

yep re-gear, problem solved. should have done it already with those tires! 5.29!!

elripster

I have 4.88's and 31's, you need to regear to 5.29's.

Frank

ZUK

iTrader: (1)

I was thinking the same thing as tc....too much tire(rolling resistance) and not enough gearing.
My ole 87 Runner with 22RE auto 33x10.50 tires and 571 gears held the highway fairly good from Chandler to Tucson. I set the cruise for 75 real mpg and it would downshift on those upgrade sections between Casa Grande and Picacho Peak....not bad for a 22RE though. Of course, with the cruise off it no longer did the downshift thing.
Just to let you know, I have all the stuff for a re-gear for you.....488 or 529 Motive gears. Well, I have everything except the front ring and pinion but that can be had in short order. See my webpage. ZUK

snap-on

monster overdrive is an understatement, i drop 1500 rpm when i hit OD. compleatly misses the sweet stop of a 3vze In my experience.

there is a reason they call them 3.slow! (i hate my 3vze infront of a stock A340H) I LOVE my 3vze infront of my 5speed! NIGHT and day diffrence seriously! (dont get me started on towing)

mt_goat

I say have Zuk put in 5.71s. I ran 5.71's with a 3.slow auto and 33's for over 40,000 miles, you will love it. I also ran 5.29s and 4.88s. The 5.29s are still too tall for the 33s and 3.0/auto tranny but you can use OD some with a tail wind. The 4.88s are a little too tall for even 31s.

tc

Yeah, Molly has 5.71 with auto and 35's and is has the same problems as the OP, maybe worse since we're at altitude. I would go 5.71 with 33's and fugheddabout running 35's with an auto on the highway.

4x4_Ferg

Thanks for the advice. My gear ratio is 4.10, so I definitely have a pretty poor configuration, running 33x12.50's with the 3.0 and auto tranny. I figure I'll start saving some extra cash for some new gears. My truck is my daily driver (40-80 miles per day average) and my toy, so I need a gear ratio that is somewhat good on gas and doesn't make the motor scream at freeway speeds. For those of you with the 3.0 auto, 33's, and 4.88's/ 5.29's/ 5.71's, what kind of rpms are you seeing while cruising at freeway speeds (65-80)?

CoedNaked

what RPM"s is your overdrive turning at 70-75 MPH out of curiousity?

shoes138

yea man the autos suck, i wish i had a manual tranny. when im cruising down the street at about 25 mph my truck is already in O/D.

mt_goat

Here's a good calculator:
http://www.grimmjeeper.com/gears.html

The Toyota trannys are already programed in just select your A340H and the tires, gears and speed.

By the way, RPMs don't have much to do with fuel economy, MPG is all about throttle and staying out of open loop. If you are geared too high and have to keep the throttle above 80% that sends the ECU into a rich open-loop mode and there goes your MPG. I'd rather be running at half-throttle and 3500 rpms and be in the peak of the powerband than full throttle at 2500 rpms and unable to pull the gear.

tc

Exactly. MPG is more about throttle position than RPM.

Mine is a manual tranny, but at 70 MPH, I'm at 3000RPM, just on the low side of the powerband. I think Molly's automatic is at about 2500 RPM, but it's hard to say, 'cuz it's never in OD long!

4x4_Ferg

Zuk, I may be interested in installing some 5.29's. About how much would I be looking at for the whole thing? I know when I first got my lift/ tires, 4Wheel Parts quoted me $1,400, which is more than I can afford to spend. Let me know.

4x4_Ferg

Coednaked, to answer your question, it varies somewhat. When OD is on, it is sometimes in the 2400 range, but it'll usually jump up to about 2900 unless I'm going downhill, but I guess it is still in OD when this happens, because when I turn the OD off it's at about 3400-3600.

mt_goat

When it jumps up to 2900 your torque converter is unlocked generating lots of heat, your ATF can cook when you run like that for very long. Have you ever had the AT temp light come on?

ZUK

iTrader: (1)

ok....Having 571 gears and using OD on the highway is fairly close to the same as having 410's and using 3rd gear on the highway ...so take it down the highway in 3rd and see if you can live with an OD like that.
My 87 Runner with the 571 gears and 33" tire did just under 3400 rpm at 75 mph per GPS readings. Using basic math.....that is the same as doing 65 mph at 2946 rpm.

4x4ferg....you have pm.

4x4_Ferg

No, I have never had my AT temp light come on. Most of the time I am crusing I am in this OD/ torque converter unlocked mode too, because it seldom holds the locked mode for very long. This included a nonstop drive from Portland, Oregon to Tempe after I got the tires. I recently installed a good-sized tranny cooler and added a bottle of Lucas tranny fix, so I am hoping that will hold off any problems. As of now my tranny seems to work fine.

CoedNaked

According to the calculator - with 4.10 gears and 33" tires, with the A340H transmission, at 1750 RPM's you're doing 59 miles per hour, and at 2250 RPM's you're doing 76 miles per hour. That's not THAT bad in my opinion. I do however think the 3vze cruises better between 2250 and 2750 RPM's on the highway, but anything above 2000 RPM's should cruise descently with this engine.

The overdrive in this engine is 0.71 for the 4th gear.

Mind you I am also not factoring in that this automatic transmission isn't the most efficient unit - at least not as efficient as the manual at putting horsepower to the rear wheels.

I'd say in your case just jump up to 4.88's. Maybe consider dropping down to 33 x 10.5's too - that should help with power a bit as well.

Joey

Zuk those rear spring mod pics are awesome. Great work and great images.