700R4 help

[86C20crum]

Sorry I had to edit that post. I was wrong, I think. Lol
They made at least 15 different type VB setups..which include the wiring as well (from 82-86). I have at least 12 of those diagrams..but hard to say what you have inside without knowing the model # at least or removing the pan, even better.

Here's my 8th attempt at loading the image I wanted to in the last post

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Thanks for the pic. I guess the only way to tell is to pull the pan?

 

[Cuba]

I'm leaning so but before you do.... There should be a stamped code towards the rear of the passenger side just above the pan. It's a number then letters... 1st number is for the year, the 2nd two digits should be the model.

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In fact sometimes the camera can see the digits better than our eyes. The trans I have pictured above is a model TL.

Or take a pic & post it, so we can help decipher it.

There's also a big white tag on the top of the driver's side, but you may not have one legible or too high up to see it. This is mine...

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Notice the k stamp? These were thicker made cases usually built for the 4x4s

Is your truck a 4 or 2 WD? If you wind up needing to drop the pan, grab a filter too. Doesn't hurt. But if you can avoid doing anything until the others have had a chance to chime in. Some of these guys work during the day, but are quote regular

 

[86C20crum]

Here are the numbers:
6MKM-Y-00465682-317H

 

[Cuba]

Here are the numbers:
6MKM-Y-00465682-317H

It's very possible you have type 1 then... especially if it's the original to the truck one.

Here's its diagram:

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I'm trying to see if I can find way to test those solenoids. In other trannys, they give you 2 ways to test them by 1st jumping them with 12v and listen for function. Then to check amp draw or sometimes ohming then out.

I'm surprised none of the tranny guys have showed up here yet...

 

[Honky Kong jr]

It's very possible you have type 1 then... especially if it's the original to the truck one.

Here's its diagram:

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I'm trying to see if I can find way to test those solenoids. In other trannys, they give you 2 ways to test them by 1st jumping them with 12v and listen for function. Then to check amp draw or sometimes ohming then out.

I'm surprised none of the tranny guys have showed up here yet...

Any solenoid coil can be tested via Ohms or if you have one I do,so I do they can be Megged. Also a Megger is good for getting rid of unwanted neighbor dogs that come in your yard. A little pokey pokey a yelp and they run off.

 

[Cuba]

Any solenoid coil can be tested via Ohms or if you have one I do,so I do they can be Megged. Also a Megger is good for getting rid of unwanted neighbor dogs that come in your yard. A little pokey pokey a yelp and they run off.

Problem is I have no listing as to what these should measure, so far. I'll have to post tmrw since I have an early day. Maybe by the time I'm off wrk others have given there feedback or thoughts. I'm no tranny pro.

 

[Honky Kong jr]

Problem is I have no listing as to what these should measure, so far. I'll have to post tmrw since I have an early day. Maybe by the time I'm off wrk others have given there feedback or thoughts. I'm no tranny pro.

It's always good to have a known good unit as a baseline.

 

[Cuba]

True...but as I stated above not all of these units have solenoids, and not all have the same ones. If they're anything like other trannys, they vary in resistance depending on the clutch pack or job they perform.

 

[Honky Kong jr]

True...but as I stated above not all of these units have solenoids, and not all have the same ones. If they're anything like other trannys, they vary in resistance depending on the clutch pack or job they perform.

Not to bring up VW but we had a test bench for them and yeah I will stick with my Th400s lol.

 

[MikeB]

I'm surprised none of the tranny guys have showed up here yet...

Gotta be some auto trans forums out there, maybe even 700R4 focused.

Also, I learned a ton about TH350 operation in an HP book by Ron Sessions. There must be similar books for 700R4.

Also, this is one of the many forum threads I found by doing a Google search on "700R4 no third gear".
https://chevroletforum.com/forum/si...-21/lost-3rd-gear-my-700r4-transmition-39187/

 

[yevgenievich]

A loss of a third gear only would lead to extensive troubleshooting. Checking line pressure during shifting, checking the vb gasket... And then it still can be one of those seals being torn on the inside.

Can drop the pan to see how things generally look and check if there anything floating in the pan

Edit: was in a 4l60e mode for some reason

 

[86C20crum]

Gotta be some auto trans forums out there, maybe even 700R4 focused.

Also, I learned a ton about TH350 operation in an HP book by Ron Sessions. There must be similar books for 700R4.

Also, this is one of the many forum threads I found by doing a Google search on "700R4 no third gear".
https://chevroletforum.com/forum/si...-21/lost-3rd-gear-my-700r4-transmition-39187/

Thanks. I've read this article before. Doesn't seem to be the same issue as I have.

 

[86C20crum]

Ok. I'm sure my lock up is not working at all. The 2 vacuum switches on the firewall, the one on passenger side is hooked up with a vacuum line going to one on driver's side. That one isn't plugged in and doesn't have a vacuum line going to it. Does it need to be on full vacuum from the manifold or ported? Could that cause my problem? I wouldn't think so but I have been known to be wrong.

 

[MikeB]

I just found this GM service manual for 1987 light duty trucks, but you can probably find one for 86.

Check out Section 7 (pdf page 950) here: http://www.73-87chevytrucks.com/tec...Chevrolet_Light_Duty_Truck_Service_Manual.pdf

Section 7A-31 is the beginning of preliminary checking and diagnosis.

Section 7A-2 covers converter clutch operation. Several parameters control the lock-up.

I'm sure there are also vacuum line diagrams somewhere in the manual.

I think I paid around $10-$15 for an 82 service manual on CD. Nice thing about it is a menu on the left side of the screen that makes it easier to navigate.

 

[JON79C10]

Hi All, Newbie here, 1st post. Not new to forums, just this one. Have 79 C10 here in U.K. I am a professional transmission builder who only rebuilds 50-90's American transmissions and I specialise in 700R4s. I joined this site the other day because I am rebuilding my truck and wanted information and also like to help you guys if I can.

I read this thread with some concern as I am reading some things which are simply not correct and can be misleading to the person who has the problem with his 700R4. Nobody wants to go spending money and time for nothing so I feel the need to chip in, hope not to offend anyone previously trying to help.

The 700R4's are good when they are ok (I have a performance one in my 79) but bad when they are tired and need plenty of TLC when they are repaired. They are complicated in operation and design and have weak spots. The 3rd gear clutch pack is usually the first thing to go when a rebuild is due. 90% of all that come into the shop have 3rd gear burnt up. The fault is not the actual clutch, it is weak leaky hydraulics that feed it, caused by wear and tear. They can also fail due to the TV cable being out of adjustment (more on that another time) Also more on Lock up another time. These are two areas which need a ton more clarification and I will try and write a 'sticky thread' at some point

I'll be perfectly frank with you - do not spend any money or time on this transmission. From what you have said about your problems - IT IS BURNT UP already. Nothing will cure it other than a complete rebuild. Save your pennies for this.

The way the 700 gears work is as follows - 1st is engaged mechanically already and selected by the forward clutch (Drive) 2nd is operated by the band (operated by the servo on the side) 3rd is operated by the 3rd clutch (its burnt thats why it goes to neutral, it cant hold) 4th is operated by 3rd and 2nd band together) Sometimes 4th works if it can hold the 3rd if you are cruising gently. If not there will be no 4th either because it needs 3rd. I hope that makes sense.

You cant always go by the fluid colour or smell. Sometimes the PO has already changed the fluid in an attempt to 'fix' the slipping and then decided to sell after it didnt!

I hope this information helps, probably not what you was hoping to hear but its just fact.
Cheers Jon www.americanautomatics.co.uk