Towing with the 700R4

[1984k20]

Hello everyone !
I'm new here, and have a question I hope someone can shed some light on.
I have a 84 Silverado 6.2 diesel 4X4 with a 700R4 trans. I don't drive it much, except to pull my car trailer. Trailer weighs 2,000 lbs. car on trailer weighs 3,800 lbs. So, roughly 6,000 lbs. plus whatever my truck weighs.

I'm worried about burning up the trans. I recently bought a car for my wife and hauled it about 400 miles to home. Only recently, have I found out about these transmissions in the early 80's not being dependable. I crawled under the truck today and got the I.D. off the trans case. 7TXM-Y-00514002-280C

I don't want to have any issues what-so-ever with breakdowns due to the trans. So, I've been reading all I can find about a proper / positive fix. I have to honestly say I don't know what to do yet.

My DD is a 2002 S10ZR2. It has a 700R as from GM. It's the electronic version. That trans went out at 42K miles. Sun shell broke. This was just cruising at about 45 mph! That happened a couple years ago. When that happened, I did some research & discovered about the weak link with the sun shells. Didn't know anything about that potential problem beforehand.

I've built TH 350's & 400's in the past for myself, so I figured I'd tackle the 700. I did some upgrading while I had it completely dismantled.

So I'm not afraid of doing a rebuild, I just don't know which trans to use!
This truck (84) will be used to tow around 6K pounds payload.

I know this issue has really been beat up, but I would really appreciate some knowledgeable input as to a fix to avoid any future problems.

Thanks,
Randy

 

[89Suburban]

Damn that truck is beautiful!
@HotRodPC is the trans rebuild guru here.

 

[HotRodPC]

Hello everyone !
I'm new here, and have a question I hope someone can shed some light on.
I have a 84 Silverado 6.2 diesel 4X4 with a 700R4 trans. I don't drive it much, except to pull my car trailer. Trailer weighs 2,000 lbs. car on trailer weighs 3,800 lbs. So, roughly 6,000 lbs. plus whatever my truck weighs.

I'm worried about burning up the trans. I recently bought a car for my wife and hauled it about 400 miles to home. Only recently, have I found out about these transmissions in the early 80's not being dependable. I crawled under the truck today and got the I.D. off the trans case. 7TXM-Y-00514002-280C

I don't want to have any issues what-so-ever with breakdowns due to the trans. So, I've been reading all I can find about a proper / positive fix. I have to honestly say I don't know what to do yet.

My DD is a 2002 S10ZR2. It has a 700R as from GM. It's the electronic version. That trans went out at 42K miles. Sun shell broke. This was just cruising at about 45 mph! That happened a couple years ago. When that happened, I did some research & discovered about the weak link with the sun shells. Didn't know anything about that potential problem beforehand.

I've built TH 350's & 400's in the past for myself, so I figured I'd tackle the 700. I did some upgrading while I had it completely dismantled.

So I'm not afraid of doing a rebuild, I just don't know which trans to use!
This truck (84) will be used to tow around 6K pounds payload.

I know this issue has really been beat up, but I would really appreciate some knowledgeable input as to a fix to avoid any future problems.

Thanks,
Randy

So you are asking which model trans to rebuild, or which of the 700r4's to rebuild? You'd prefer an 88-92 model 700r4.

 

[HotRodPC]

So you are asking which model trans to rebuild, or which of the 700r4's to rebuild? You'd prefer an 88-92 model 700r4.

If you plan on towing in OD, I'd plan on a Superhold 3/4 Servo, and Alto Commercial 3/4 clutch pack or at least Raybestos Z Pack.

 

[1984k20]

Damn that truck is beautiful!
@HotRodPC is the trans rebuild guru here.

Thank you, 89Suburban

 

[1984k20]

If you plan on towing in OD, I'd plan on a Superhold 3/4 Servo, and Alto Commercial 3/4 clutch pack or at least Raybestos Z Pack.

Yes, I'm hoping I can build a 700R that I can tow in O.D. with.

Looks like a major project (for me, anyway) to go with a 4L80. Too much work.

My truck has what I think is a 87 700R in it now. It's a "K" case, too. What is it about the next year 700 & up that's so much better ?

Thank you Hotrod, for your input. I really appreciate it.

 

[HotRodPC]

Yes, I'm hoping I can build a 700R that I can tow in O.D. with.

Looks like a major project (for me, anyway) to go with a 4L80. Too much work.

My truck has what I think is a 87 700R in it now. It's a "K" case, too. What is it about the next year 700 & up that's so much better ?

Thank you Hotrod, for your input. I really appreciate it.

The 87 is the first year you'd want to start with. It's the first year for the additional valve body and an abuse valve along with other changes for the better. The 88-92's have other little minor changes too. So an 87 is a good one, the 88-92's are tad better for an update that I now forget. The 86 and older units wouldn't be worth your efforts. So if you have the 87 K case unit then go with it. The K case is supposed to be a bit beefier in the bell housing area and that's about it, however that can be considered quite a difference depending on what you intend to do with it. So to answer your question the next year up isn't SO MUCH better. It's the 87 up that is SO MUCH better by having the secondary valve body including the abuse valve for rocking in the event you get stuck and try to rock the truck out of a hole.

 

[Dadof2]

I don't have any info for your trans question, just had to chime in and say that is one of the sharpest trucks I have seen.

 

[MadOgre]

If your transmission has the serial number down by the pan it is 86 and earlier. The desirable ones to rebuild have the serial number up on the bell housing

 

[1984k20]

If your transmission has the serial number down by the pan it is 86 and earlier. The desirable ones to rebuild have the serial number up on the bell housing

I thought I had a 87 trans, due to the first digit being a 7 ? The I.D. is stamped in the side of the boss located at the rear passenger side of the pan.

 

[HotRodPC]

I've never heard that Ogre. It's always down on the stamp pad of the case just above the pan on the right side of the case toward the rear.

 

[MadOgre]

My 90 700r4 out of a burb has no serial number by the pan. I do know for a fact that it was a GM replacement transmission. Now I cant remember if it was because it was a replacement or if it was the year? That the serial number is not there. I am pretty sure when I researched it was because of the year.

 

[HotRodPC]

Replacement transmissions rarely had a serial # on them in their standard location. They'd get a sticker up on the bell housing.