Second Trans failure in 200 miles

[morgy83]

Hi all, hoping this is just bad luck but want to get your take just in case. 83 short bed with 355 posi rear and 350 crate motor. Lost first, 4th and reverse gear on 700r due to edlebock TV cable not being installed correct. Bought new 700r from reputable builder, bought correct bracket for tv cable, had reputable shop install and after 200 miles that trans failed too. I would think it was something with the rear end, drive shaft or rear end causing this but the failure was completely different. Lost speedometer first then ten minutes later lost all but first gear. Did not lose fluid but Trans did over heat and is now a goner. It had a warranty so sending it back for new one but is there anything I should be looking for on the truck that could have caused this? I am thinking not and it’s just bad luck (maybe Speedo cable come lose and wrapped around trans to kill it this last time) but thought I would check in in case anyone had any insight.

 

[84 M1008]

First, always run an external cooler with a 700R4, preferably a fan driven one. The shop more than likely didn't set and adjust the cable properly. I installed my own Monster 700R4 years ago and set and adjust the three times before I was satisfied with the adjustment.

 

[morgy83]

Well had a guy who has done tons of these with no problem install. One of the reasons I had bought the trans from the company I did was due to it coming iwth larger high capacity cooler. Trans shopp swears up and down the install was done 100% correct. Drive perfect with no issues at all for 200 miles then sudden catostrophic failure.

 

[hatzie]

Are you sure your mechanic installed the aftermarket cooler and not just the original factory loop through the radiator?

Did your mechanic flush out the cooler and the lines?

I'd check the cooler and lines for blockages. I usually install a Magnefine transmission filter in the return from the cooler as well to catch any crud I didn't manage to clear out of the lines and cooler. The filter lets me service the transmission filter when I do the motor oil around every 5K miles or every year. No more dropping the pan to change the strainer because the filter is media is finer than the strainer in the pan... The filter is 25 microns the strainer is 110 microns.

Be sure the TV cable and bracket is the correct unit for your carburetor and transmission... and the ball stud for the TV cable is in the correct location.
Just because you bought a "correct" replacement doesn't mean the mechanic installed it correctly or at all.
Be sure it's properly adjusted as well.

One of the reasons I like to run Rochester Quadrajets is there's no ambiguity on these kind of brackets and studs.

 

[436'd skylark]

What are you running for a converter? Did you replace the converter? Was the cooler cleaned out? Losing the speedo is odd. Did the cable come off and puke the fluid?

 

[morgy83]

Brand new trans. Built from scratch so everything was new. Cable still attached. Lost no fluid.

 

[MikeB]

Well, I kinda doubt the trans overheated and died in 200 miles due to lack of an auxiliary trans cooler. However, Bowtie Overdrives says >60% of 700R4 failures are caused by improper action of the TV cable. Notice I didn't say "adjustment", because I know of at least one cable that had its travel limited by the rod (the part you connect the cable to at the trans) hanging up in the cable housing, thus limiting pressure. And that was with a brand new OE-type cable and rod.

Since you're depending on other people for the work, I'd suggest using a shop that rebuilds AND installs the trans, and gives you a warranty on the work.

 

[krcaddis]

My '91 2500 4x4 was 2 years old when I bought it. After a year, or so, I lost 4th (700R4), soon 3rd, on a long trip. Had it rebuilt in AZ an AAMCO shop. I saw damaged parts, a ground down AL valve body (?). Had it rebuilt and added an external cooler. No explanation as to why. 6 months later the flex plate broke. Had it replaced at a local AAMCO dealer, no reason why. Few months or so later, 4h went out again. Went back to Seller (his Dad had a AAMCO shop), and had it fixed free as seller guaranteed the truck fr a year. Then the flex plate broke, had it fixed locally at an independent shop. Then it lost fourth again, out of warranty and by then I know the BF of a girl I worked with rebuilt it. He worked for the local GM dealer and rebuilt ATs there. NONE of those shops could explain why the tranny or the flex plates kept failing. I sold the truck cheap.
Now I have an '85 C-20, TH350, long bed 2WD with a fresh 350 crate motor, but the shade tree wrench I hired must have wrecked the new front tranny seal installing, as it loses fluid like 88 cent pitchers go on Friday night. 3 Pints to the local dump and back, 45 miles. Since there's NO easy fix, I'm considering a used 700R4 and driveshaft from a late 80's van or PU using the right size driveshaft, pretty much a bolt-in,moving the X member I read. I don't want to spend a lot, so I'm shopping for a freshly wrecked, running pair I can test drive or at least shift while on blocks. I'm tired of 10-15 mpg; the truck has only 41k on it, zero wear, zero rust.
Any good advice?

 

[Obwonkonobe]

If you have a 9 inch tailhousing on the 350, the drivshaft will swap. That's how I did mine