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Do I need to rebuild my trany?


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brian110
New User

Dec 21, 2009, 5:47 PM

Post #1 of 6 (1816 views)
Do I need to rebuild my trany? Sign In

Hello, New comer here.

I just bought a van for $600 (cheap I now, Had to be something wrong with it, right?). First thing I notice was that going from first gear to second, the van would jerked foreword in a roughly fashion (1st gear revs vary high before shifting). I can nearly eliminate the thump if I release the gas right before it shifts. As I release the gas, it'll shift when the RPM's are declining. If I timed it wrong and it shifts when the RPM's are high, I'll get a thump.

As it shifts from 2nd gear to 3rd, it would bounce forward and back as if it was a stick shift ie. if you would release the clutch to quickly. Shifting from 3rd to 4th is flawless. I get the same thump from 2nd gear to 1st, but not as violent.

Do I need to get the trany rebuilt?

How much driving time you think I can get?

Thanks


(This post was edited by brian110 on Dec 21, 2009, 5:48 PM)


Dieselrotor
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Dieselrotor profile image

Dec 21, 2009, 5:55 PM

Post #2 of 6 (1808 views)
Re: Do I need to rebuild my trany? Sign In

First, what make, what model, what year van ? depending on make ,model, year it may be a modulator or or shift selenoid' If you have all gears but rough shift.


brian110
New User

Dec 21, 2009, 5:58 PM

Post #3 of 6 (1805 views)
Re: Do I need to rebuild my trany? Sign In

Ops sry forgot,

1987 GMC R2500 conversion van V8 350ci 150,000mi


brian110
New User

Dec 21, 2009, 7:31 PM

Post #4 of 6 (1797 views)
Re: Do I need to rebuild my trany? Sign In

Think I found the problem!!!!!!!

look This part is missing on my van.

Can this be the problem?

The plunger and switch is missing.
only thing that is there is the mounting braket




Dieselrotor
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Dieselrotor profile image

Dec 22, 2009, 6:04 AM

Post #5 of 6 (1785 views)
Re: Do I need to rebuild my trany? Sign In

I am sorry, I can not view the picture. I just have a red X where the picture should be.
Being a 1987 though, You will have a vacume controler called a modulator that is located on the transmision.
There is a vacume line that runs from You're manifold near the venturie outlets in the back of the manifold and probably connects to multi tree'd vacume port. This vacume line runs to the modulator on the trannie, inspect the line and look for leaks or just unplugged. If not unplugged or if even still plugged in, unscrew the moduleator and inspect it for fluid. it should not have any tranny fluid in it, but to be safe anyway, i would just replace it. and if possible, replace the vacume line too to be safe. if it's cracked and leaking ,You will have the same problem with the new modulator.
Hope that's all. Good luck.


Dieselrotor
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Dieselrotor profile image

Dec 22, 2009, 6:15 AM

Post #6 of 6 (1784 views)
Re: Do I need to rebuild my trany? Sign In

P.s-sorry, forgot to address the plunger thing You found, is the plunger thing inside the van near the gas peddle ?
If so, it is the detent switch, on some older models the detent was a physical cable attached to carberator that put the transmission into passing gear when the throttle was pressed passed a certain point and was adjusted right on the carberator by releasing the grips and then having someone depress the gas peddle then release the grips and the detent was set. Some ued a selenoid driven detent witch You may have. The detent does not control normal shifting, just the ability to shift down to a passing gear. But yes, if it is what i think it is, it should be replaced too, to keep You're van from loading up and bogging when You try to acclerate such as when entering a freeway or passing or under heavy loads. I hope I am thinking right this early in the morning and the switch is what i think it is. Again good luck.






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