Very strange transmission problem

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Very strange transmission problem

Postby Undercurrent » Mon May 08, 2017 10:51 pm

I hate to say it....but I need help,I rebuilt a 1999 Isuzu trooper 4l30e transmission.before the rebuild it ran and shifted fine,but a needle bearing went out and was immediately parked. So I just rebuilt it last week,followed 2 manuals and put it back together EXACTLY as specified. Replaced anything that even looked like it would cause a problem. Planetary gears,all clutchpacks,torque converter,all gaskets and seals. So here is what it's doing,I have it on jackstands,proper fluidlevel,ran through all the gears,in park the engine is under load,shift to R and rpms raise 2-300 and no wheel movement.shift to N and rpms go down,again engine under load and wheels rotate as if in drive. Shift into drive,same as N,wheels rotate but no amount of accelerator will make the speed increase,they just slowly turn forward. Shift into 3,2,L, they respond the same,a slow turning of the wheels in a forward direction. If I engage winter mode,the wheels will actually spin up with the accelerator. I triple checked the one way roller bearings upon assembly,I thought maybe the tc wasn't seated proper,dropped the tranny again and checked,it's good, then maybe a sticking valve,checked them, maybe range sensor,checked it out,it's good.what would cause it to have no reverse,and wheels spin forward in every gear but no acceleration? Tcc solenoid? This thing is driving me insane
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Re: Very strange transmission problem

Postby Tg16 » Tue May 09, 2017 1:26 am

did you check the Main Solenoids are not swapped?

Do you have a PWM or Non PWM trans???

If you have a PWM trans 2 solenoids are different.

Also check your Wiring for Cracked connectors

if you have a scan tool that support transmission you can see what it's doing.

Also the Chinese TECH2 on Alibaba Actually works and will tell you much more about your whole vehicle.

I just bought one.
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Re: Very strange transmission problem

Postby Undercurrent » Tue May 09, 2017 2:43 am

I don't have a scan tool that'll do transmissions. The tranny is non pwm, all solenoids and wires are where they are supposed to be. The vehicle has been taken care of and is in really great shape and never abused or taken off road. I thought I might have had a check ball in the wrong place,but I checked that again too.
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Re: Very strange transmission problem

Postby Buster28 » Tue May 09, 2017 7:26 am

Disconnect the 4 pin main case connector to disable the shift solenoids and brake band solenoid. Then shift the transmission manually, with the shift solenoids disabled (R = R), (L = 1st), (2 = 3rd) and (3 or D = 4th).

If Reverse does not operate correctly but L,2,3 and D do the sprag clutch is installed backwards. In Reverse the sprag clutch drives the planetary input sun gear but in L 1st and 3rd and 4th gear the 3rd clutch drives the planetary input sun gear. Winter Mode is 3rd gear.
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Re: Very strange transmission problem

Postby Undercurrent » Tue May 09, 2017 9:41 am

Ok,that [i]seems[i] to have given me L,2 3 and D . N is still doing the slow wheel turn,and no R still.
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Re: Very strange transmission problem

Postby Undercurrent » Tue May 09, 2017 9:43 am

When you refer to the sprag clutch being reversed, do you mean the entire assembly, the one way roller, or just the gear.Just trying to clarify so I can have a better understanding of where I went askew. I bought a whole new sprag clutch assembly,it came assembled so I just put it in,didn't think anything of it,but I'll pull it out when I get home and give it a look.
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Re: Very strange transmission problem

Postby Buster28 » Tue May 09, 2017 10:32 am

If the sprag is installed backwards it will unlock instead of lock in Reverse
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Re: Very strange transmission problem

Postby Undercurrent » Tue May 09, 2017 10:47 am

Sorry ,I thought you were referring to the overdrive/over run assembly, ok I'm with it now,and the sprag clutch assembly is the one way roller I check repeatedly before installing bc the Hans V. Manual had it underlined,highlighted and bold italics to get it right,lol. Could the clutches themselves be hanging up inside the assembly? I know when i reassembled it,it felt like it was wanting to hang up and took me awhile to get it to all together.
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Re: Very strange transmission problem

Postby Buster28 » Tue May 09, 2017 1:37 pm

Undercurrent wrote: Could the clutches themselves be hanging up inside the assembly? I know when i reassembled it,it felt like it was wanting to hang up and took me awhile to get it to all together.


If the 3rd clutch frictions were dragging it would not cause a Reverse problem but would create a mechanical bind in 2nd gear because the 3rd clutch frictions would be driving the planetary input sun gear at the same time the 2nd clutch is driving the planetary ring gear input.

When the 2nd clutch is applied the integral ring gear drives the planetary long pinions, since the long pinions mate with the short pinions the planetary input sun gear rotates backwards which normally unlocks the sprag clutch. However, if the 3rd clutch frictions, which also are connected to the planetary input sun gear, are dragging they probably go up in smoke. If the sprag is backwards a bigger problem is created because the sprag locks instead of unlocking and won't slip like the 3rd clutch frictions.
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Re: Very strange transmission problem

Postby Undercurrent » Tue May 09, 2017 1:48 pm

Well I don't think I've burned anything up yet,haven't driven it obviously lmao,fluid still looks good no debris in the pan. I'll have it out in about an hour.
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Re: Very strange transmission problem

Postby Undercurrent » Tue May 09, 2017 4:50 pm

Ok,here's an update so far,a thrust washer between sprag and overdrive assembly,is confetti ribbons now,the sprag assembly was somehow jambed on top of one of the outer metal clutches.

* edit* And THE SPRAG IS WRONG,WTF!! did I grab the old one?! Is Ashton kutcher gonna jump out and yell ah ha?! Idk what happened there,i was liyerally staring at the manual and comparing as i put it together,but good call,you nailed it there.
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Re: Very strange transmission problem

Postby Buster28 » Tue May 09, 2017 8:53 pm

Undercurrent wrote:Ok,here's an update so far,a thrust washer between sprag and overdrive assembly,is confetti ribbons now,the sprag assembly was somehow jambed on top of one of the outer metal clutches.

* edit* And THE SPRAG IS WRONG,WTF!! did I grab the old one?! Is Ashton kutcher gonna jump out and yell ah ha?! Idk what happened there,i was liyerally staring at the manual and comparing as i put it together,but good call,you nailed it there.

And I didn't need a Chinese Tech2 to figure it out either.
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Re: Very strange transmission problem

Postby CalG » Tue May 09, 2017 9:57 pm

I sensed a problem when I read "put it back together exactly as specified". ;-) These same kinds of things haunted my sleep when I rebuilt my own 4L30e.
That Buster28 can so accurately describe the workings and operation is a real boon to all!. I wish I could remember this stuff! ;-)
Thank you BUSTER28!

Sorry about your troubles undercurrent. These things are hard!
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Re: Very strange transmission problem

Postby Undercurrent » Tue May 09, 2017 10:22 pm

Every thing is under control now,lol,thanks buster. I might get some sleep tonight instead of mentally going over everything in the transmission. The rebuild wasn't actually that bad,it's the getting it in and out of the vehicle,and hopefully out for the last time now. Thanks for the help
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