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AW4's fifth gear!

Ecomike

NAXJA# 2091
NAXJA Member
Location
MilkyWay Galaxy
OK,

Now that I have your attention, I think I finally figured out that what I once thought was a fifth gear, and a very short, unusually rapid shifting of gears from third to fourth to fifth, is actually the torque converter lock up, :banghead:, on my AW4 (the FAQ here says I have an AW4,.... 1987 4.0, wagoneer, 4x4 ltd.) between third and fourth gear.

On light, normal take off acceleration from a dead stop it usually happens after third gear engages around 35 mph, and at about 2200 rpm and then it drops the rpm to about 2000. Then shortly after that it switches to fourth gear. Once the torque converter locks up the rpm stays in a narrow range as you decel and accelerate, like I have read it should. So do I have it right now?

Since I was confused by this (for quite some time) I thought this was worth sharing.

So does 40 mph sound too soon for the fourth gear to engage?
 
I have noticed that my 89 does the same thing.

Sometimes it has a hard time decded weather or not it wants to lock up or not.

Doesyours do this as well??

Paul
 
Paul R said:
I have noticed that my 89 does the same thing.

Sometimes it has a hard time decded weather or not it wants to lock up or not.

Doesyours do this as well??

Paul

Yes, but only when I am in 30 to 35 mph speed limit zones with short distance between lights and stop signs.

If I get on a long straight road and slowly, economically accelerate (say 0-40 in about 15 seconds) it will typically lock up at about 40 mph.

But I must admit it is a little difficult to tell if it is lock up or fourth gear that is engaging first!???:confused1
 
nekocopter said:
Go buy the lockup module... Then you'll have complete control of it.

Lockup module???? Where?
 
Actually, depending on how hard you're accelerating, it can be stranger than that, because the AW4 in OD mode will lock up in both third and fourth gear. My 87, when driven gently, would sometimes lock in third, and then apparently shift from 3 to 4 still locked, but you could also give it a little goose at the right time and make it unlock for the shift and then lock again in fourth.
 
Matthew Currie said:
Actually, depending on how hard you're accelerating, it can be stranger than that, because the AW4 in OD mode will lock up in both third and fourth gear. My 87, when driven gently, would sometimes lock in third, and then apparently shift from 3 to 4 still locked, but you could also give it a little goose at the right time and make it unlock for the shift and then lock again in fourth.

Thanks for the feedback Matthew. I think I recall feeling that sixth gear a few times myself, LOL. :D

It can be quite puzzling when you have been use to older cars with older non-locking torque converters and just three automatic gears like me.

In fact thanks for all the clarification answers below from all of you. I feel like I know what this beast is doing and why now.

Now I should be able to tell if and when a real problem is happening with my AW4.
 
I have a similar issue. I just bought my '91 XJ on Sunday and had to drive it back home about 500 miles. No matter what speed i was going, when i let up on the accelerator my tach would drop about 300-400 rpm. That's in OD, in 3 i don't get the same issue. When i pressed the pedal lightly, my tach would jump back up about 300-400 rpm. Also in OD when i wanted to pass on the highway i really had to bury the pedal to get it to upshift to 3rd. It's almost seems as if my tranny has 5 speeds. Weird!! Is there any fix to this?
 
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