700r4 Issues

[Cuba]

If in fact it was the front seal that blew out again, for one they make a retainer for it... but also one of the modifications is to drill the drainback hole in the pump bigger...and using the same bit to enlarge some other holes in the pump and its cover. the bit should be bewtween 9/32" to 5/16" (.281 - .313). The bushings are usually lightly staked to prevent the walkout that used to occur... there's also a bleed hole in that area too, but if that had been blocked up, I'm sure you would have had issues sooner.

 

[74 Shortbed]

The newer pumps have that hole in them, I don't have no faith in that clip on retainer..

 

[Cuba]

The newer pumps have that hole in them, I don't have no faith in that clip on retainer..

I edited after looking up the info and verify with my notes... it's enlarging that existing hole and enlarging others.

No, i wouldn't trust the retainer solely either... just added help

 

[yevgenievich]

Regarding lock up. If it is not wired internally and is disconnected, fluid temps will be high, especially if it is pre aux valve body 700r4. Make aure if it is fixed, that there is a good cooler, temp gauge and working lockup at least using a switch. On my 4l80e the older programming does not engage lockup in 3rd gear, but that causes high trans temp when towing in 3rd gear. I ended up adding a toggle switch for the rare case of heavy load making me keeping it in 3rd. I have also watched temps with lock up vs no lockup and lock up was very usefull for temp control.

 

[74 Shortbed]

Both mine are 92's and they never heated up, but like I said, don't run the rpm's below the stall speed unlocked..

 

[74 Shortbed]

Another important factor is the input/output shaft seal, most kits come with a plastic seal they are junk you'll starve the planetary, always use a Viton seal..

 

[HotRodPC]

If in fact it was the front seal that blew out again, for one they make a retainer for it... but also one of the modifications is to drill the drainback hole in the pump bigger...and using the same bit to enlarge some other holes in the pump and its cover. the bit should be bewtween 9/32" to 5/16" (.281 - .313). The bushings are usually lightly staked to prevent the walkout that used to occur... there's also a bleed hole in that area too, but if that had been blocked up, I'm sure you would have had issues sooner.

Yes, there's the fix for blowing out the front seal in the early models, that why I've asked a couple times if he knows what year transmission it is. I've assumed front pump seal the whole time due to the amount of fluid. Clip retainer is just something for GM to try and convince people they did something about the problem. Throw it away.

The newer pumps have that hole in them, I don't have no faith in that clip on retainer..

Yup, and it has the earlier pump it just needs the mods, no retainer and all will probably be just fine until the next weak link is found.

 

[74 Shortbed]

no retainer and all will probably be just fine until the next weak link is found.

And if indeed it is an early one, that next weak link will show up pretty quick..

 

[Splandman]

Yes, there's the fix for blowing out the front seal in the early models, that why I've asked a couple times if he knows what year transmission it is.

Not sure of the year now. The last time it was rebuilt he switched the cases because he was having an issue with mine, so I'm not quite sure what case was used.

 

[Cuba]

Depending on the case then, the VB may not be compatible. If using an 87 or newer VB, then older case can be used but it must be modified. One of the worm channel wall must be cut or ground out in the case.

Or vice versa. Newer case can't be used with the pre 87 VB because one of the worm channel walls is open

 

[HotRodPC]

It's my understanding that front pump seal push out mod by drilling out the holes is to lower the pressure but yet keep the same volume of fluid flowing. Less pressure it won't push the seal out but keeps the fluid volume. Similar to putting your thump over a garden hose to increase pressure when washing the car. In this case, you're removing your thumb off the hose tip, pressure is relieved but volume stays the same.

 

[HotRodPC]

DepeYou

Depending on the case then, the VB may not be compatible. If using an 87 or newer VB, then older case can be used but it must be modified. One of the worm channel wall must be cut or ground out in the case.

Or vice versa. Newer case can't be used with the pre 87 VB because one of the worm channel walls is open

nding on the case then, the VB may not be compatible. If using an 87 or newer VB, then older case can be used but it must be modified. One of the worm channel wall must be cut or ground out in the case.

Or vice versa. Newer case can't be used with the pre 87 VB because one of the worm channel walls is open

You beat me to it. I was going to say. He might have a later model case with an early model pump and a mid year model valve body and you just can't do that **** on a 700r4. I'll be quite honest, I can take a Th350 or a Th400 and you bring them to me in a basket and I'll make then work, but I WILL NOT do that on a 700r4. There are mods year after year and many parts are NOT compatible from one year to the next. Granted many parts ARE however backwards compatible, some are not. Then some that are backwards compatible, there's a complete group of parts that must be used so the one backwards mod you're making, works well with the other parts. This is why I'd just rather start with a virgin later model 87 and later, crack it open and build it with EXACTLY what it came apart with exception of the performance mods, like Servos, Sun Shell, Input Sleeves, Wider Bands, Jr Kit etc. I don't want to get into mixing and matching hard parts.

You want your head to spin? Find the 700r4 Update Handbook ATSG manual. It's a good book and it talks about all the changes 1 year to the next to the next, there were changes every single solitary year. Do you have this book Cuba? I'd imagine you do with some of the things you know.

 

[HotRodPC]

What about you Art, do you have this book?

 

[Cuba]

Yes... I have both ATSG Blue manuls & the Green update. TONS of changes. I think 93 one of the most within just the 1 yr!

 

[HotRodPC]

Next time you get a chance to get under the truck @Splandman Look at that first # in this location. That'll tell us what year the trans case is.

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