A4LD won't upshift at full throttle | Ford Explorer - Ford Ranger Forums - Serious Explorations
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A4LD won't upshift at full throttle

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'91 Eddie Bauer 2-Dr
I lost overdrive in my truck, so I fixed the overdrive band that was so loose the anchors just fell out. I also put in a Transgo shift kit to get better shifts, and I replaced the boost valve. The good news is that I have overdrive again. The bad news is that it will not upshift under full throttle into any gear. It will rev to the limiter and stay there. If let up a bit, it will shift right into the next gear. If I floor it, it will kick down with no issues. I've played with the kickdown cable and the vacuum modulator adjustments, the only thing I didn't try was completely disconnecting the kickdown cable. Is there anyone else that has had this problem after installing a shift kit?
 



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jd4242

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yep i have this problem right now and dont know how to fix it.mine also will still do it with the cable off.only way to get it to shi* at full throttle is to shift it manually on the dash.i was told it was the vacuum modulator but have adjusted mine yet.
 






jd4242

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jd4242

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Bump?
 






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I'm going to look at the valve body mods done in the shift kit, and see what could be causing this. My assumption is that it is caused by too much line pressure when the kickdown circuit is activated, or when there is no vacuum at the modulator. I see quite a few people with this problem, but no solutions.
 






jd4242

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really I haven't heard or seen this before but I havent found any solution for it yet,its annoying!!!!mine will do it with the kickdown cable off so don't think that's where the problem is.let me know if you do find a solution.
 






jd4242

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any updates?
 






BSD

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wow, someone has to have a some suggestion? Guru's?

My wifes 1993 just started doing this yesterday after a couple hour highway drive. It wont shift from 2nd to 3rd unless i take my foot off the accellerator and let it rev down and then get back into it. Then it will shift up. My searching for answers brought me here...

Help
 






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I still haven't figured it out yet, but it is related to vacuum. I can manual shift it from first to second at full throttle, but the only way to get any shifts in D or OD is to momentarily let of the gas.
 






glfredrick

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You didn't loose that little pin that the vacuum modulator pushes did you? It is the size of a small brad (nail) and easily misplaced when working on the valve body.

A delayed or non-existent 1-2 shift is probably the governor valve in the tail shaft of the transmission. When it sticks, you get no automoatic upshift.

Also, re-check band tension -- make it to factory specs using a torque wrench -- and you can back out the vacuum modulator screw a turn to decrease shift points some. This may be necessary if the valve body kit you installed increases rpm range of the upshift (as most do).

Finally, how did you check or adjust your kickdown cable? It could be off a bit.
 






jd4242

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I didn't loose it and mine isnt adjustable.its not just 1-2shifts its all shifts and will not shift even if the down shift cable is off
 






glfredrick

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If all else is good, I'd sugest that you have a sticky accumulator or a valve body that is bypassing oil or sticking a valve somewhere.
 






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It's definately somthing in the valvebody. It's a circuit that affects every gear. Does anybody know where to find a diagram that shows the fluid flow for the A4LD vb? I haven't been able to find one, it would help me figure this out. I know that another vb would fix it, but I want to figure out what is wrong with this one.
 






glfredrick

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It's definately somthing in the valvebody. It's a circuit that affects every gear. Does anybody know where to find a diagram that shows the fluid flow for the A4LD vb? I haven't been able to find one, it would help me figure this out. I know that another vb would fix it, but I want to figure out what is wrong with this one.

Do you have the ASTG manual for the A4LD? The oil routing is in there.

Otherwise, you might check this thread:
http://www.explorerforum.com/forums/showthread.php?t=126461

Found the ASTG guide online:
http://www.therangerstation.com/tech_library/pdf_documents/A4LD_manual.pdf
 






jd4242

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I'm just surprised more people that have installed this kit hasn't had problems
 






glfredrick

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I'm just surprised more people that have installed this kit hasn't had problems

If you look carefully at the ASTG manual, you'll see that your problem is generally not a valve body problem until everything else is eliminated -- such as kick down cable, linkage adjustment, vacuum modulator, fill level, etc.

After that, it can be a sticky valve or a bypass from an incorrectly torqued or torn gasket in the valve body. The good news is that you shouldn't have to pull the transmission to fix that stuff.

I've built a ton of transmissions over the years -- most "work" a few haven't. One of the more dramatic ones was when I installed the lock-up sprag backwards in a C-4 that was behind a rather snotty 302 I had built for my 69 Ford van. When it went into 3 (at full throttle upshifts that was at 92 mph) it locked the transmission solid. Imagine one of the old flat-front vans at 92, locked solid, going from side to side on the road as it slid to a stop. No motor cover, a 6000 rpm 302 screaming right next to your leg. :rolleyes: Then, just to make sure that it really happened, you do it again... :D My buddy, riding along, was on the floor wetting his pants and crying. :cool:
 






atxexplorer94

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When I lost overdrive in mine I just replaced the spark plugs and cables and that fixed it,not too much of a mechanic myself nor do i have a shift kit on my a4ld but my x would get to about 55 and start shaking in out of gear and it fixed the problem.
 






MrQ

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When I lost overdrive in mine I just replaced the spark plugs and cables and that fixed it,not too much of a mechanic myself nor do i have a shift kit on my a4ld but my x would get to about 55 and start shaking in out of gear and it fixed the problem.

That is...an unusual solution. :scratch:
 






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lost forward after shift kit install

Greetings,
has anyone found a solution to this issue yet? I installed a transgo shift kit and also lost forward, still have a delayed reverse. the real thing that is odd is sometimes it will shift, backed it out of the garage and put it in forward and it worked great until i got to the end of the road. limped it home
I have a spare valve body that i am cleaning up tonight and will install it tomorrow and see if it comes back. I think that all the cables are adjusted correctly. i put the selector in N and then the trans in N then matched up the cable length so that they matched and the kickdown should only move when the throttle is pressed down all the way?
i am just wondering if i may have done something wrong in the valve body? i must admit that i did not torque all the bolts with a torque wrench, just got them tight with a quarter drive wrench, could that be the problem?

rebuilt the transmission and nothing looked to bad but replaced all the clutch materials and rubber rings and a few of the bearing sleeves. and got the same failure mode, feels like slipping forward but sometimes works and reverse generally works but with a delay. so i will try the other non modified valve body tomorrow after it is cleaned up.

maybe it is something to do with the valve body being incorrectly torqued?
I did find when i went through the valve body that the boost valve was hanging a bit occasionally, could this be it?
well if i make it work in the morning i will post the results.
thanks for any guidance.
Joe:salute:
 



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wood1

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Hey Joe, try here...http://www.explorerforum.com/forums/forumdisplay.php?f=109

You have a factory ford manual for the A4LD? If not you should get your hands on one. Can't beat it. Mine is in storage or I would be more help...

Not sure what your skill level is, I wouldn't hand tighten a VB unless I had no choice, torque wrench only there.
 






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