1980 k5 350/np205 transmission questions

[fordsucks!]

So my 1980 transmission is losing 3rd gear once warmed up, I've taken it to two shops and both shops say problem is internal and needs to be rebuilt

One of the shops told me that my th350 has an electronic lock up, and that my 1980 has a computer that controls lock up - but mine isnt working and needs to be repaired Does this sound right? He told me that the 1980 is a rare combination of np205 with electronic lock up and some sort of full of luminum bellhousing, he says the earlier Blazers had only half of a bellhousing, quoted 3000 for th350 rebuild. I picked up my car and left

 

[6872xtc]

I may be wrong, but I thought that the TH350C, which is what they called the lock-up converter ones, had a vacuum switch to control the locking of the torque converter.
While they weren't produced for many years, I just don't see them as a $3K transmission, even with labor.
But I also have never found one with a full round bellhousing.
As far as I know, if it is full of oil, and the problem only exists when the transmission warms up, then the problem is internal. It sounds like a deal on a clutch pack leaking pressure when it warms up, but again, I may be wrong.

 

[fordsucks!]

According to Google, I think I do have the th350c. I'm about to get underneath and take a look for electrical connections to see if this dude is right.

So far the two quotes I got for rebuild are 2k and 3k.

 

[frankin5]

@Greg Ducato is the one to ask.

 

[sweetk30]

reman or new conv + labor to remove & install + good kit and tear down and rebuild ..... i could see 2 grand full shop price .

these are easy trans to remove and install . save a lot of money and pull and install your self and learn your rig when under there . then drop off the trans and have it remaned .

also call greg ducato at his shop . he does ship units . but he can also help a lot . http://www.phoenixtrans.com/

 

[diesel4me]

My '81 G-10 van has a TH350C in it..uses a vacuum operated lock up switch ..
I think they used them from 1978 to 84 or so,then the 700R4's started being standard equipment..the switch uses engine vacuum to send a 12V signal to the transmission's lock up solenoid..

I have seen many TH350C transmissions that had the "universal" bell housing that had both Chevy and Buick,Olds,Pontiac bolt patterns,so the same trans fits all...that may be what they were talking about ..but they too have an "open bottom" bell housing..

I have a spare TH350C for my van ,and both that one and the one in the van have the usual plastic dust cover over the open bottomed bell housing..I have seen 700R4's with a full round bell housing,never a TH350 though,with or without a lockup converter--just because I have not seen one doesn't mean there was never such a thing,but working in a junkyard I saw a lot !....

 

[Greg Ducato]

That is an unusual combo that they used in the 1980 model, first year for the 350 lockup with the K case for removable aluminum dust cover and used it with a 205TC instead of the 203 and just before they went to the 208. It sounds like you lost third gear which is pretty common on that unit, especially when the plastic 3rd accumulator piston breaks. If third is gone reverse should feel a bit weak as well. A total turn key price for a good quality build will not be cheap, I think the $2K price you were quoted is reasonable. Believe it or not some 350C transmission hard parts are now more expensive than those for the 700R4, who would have thought.

 

[diesel4me]

The older things get--the fewer there are of them,for cores and parts,also they probably stopped making parts after a certain time span due to the fact there isn't enough demand..

Even salvage yards and private sellers are raising the price of a "rebuildable core" due to scarcity now I have noticed..
If its a one year only deal,then that makes it that much worse!..

In a way it's wise to start collecting "spares" while some are still available..up here where everything over 10 years old gets crushed without stripping and parts off only makes things tougher when it comes to owning an older vehicle..

Perhaps this may be a good time to "upgrade" to a overdrive transmission ?..seeing it'll be so costly to rebuild the original..
You could probably get a "good used" transmission & transfer case complete with the adapter and all the other parts for less..

 

[fordsucks!]

That is an unusual combo that they used in the 1980 model, first year for the 350 lockup with the K case for removable aluminum dust cover and used it with a 205TC instead of the 203 and just before they went to the 208. I think the $2K price you were quoted is reasonable.

thank you for that insight. I am not familiar with lockup on these trucks, is it supposed to be where you feel the torque converter slipping during hard or uphill driving, and then you can feel it lockup on flat easy driving? I can feel a locked torque converter very distinctly in my Nissan trucks but I've never felt it in my blazer


Having that said, I am dropping off for the $2,000 rebuild tomorrow. I went to a few other shops for more quotes and everybody is recommending me back to the $2,000 place. Even the off-road shops

 

[fordsucks!]

up here where everything over 10 years old gets crushed without stripping

Perhaps this may be a good time to "upgrade" to a overdrive transmission ?..seeing it'll be so costly to rebuild the original..
You could probably get a "good used" transmission & transfer case complete with the adapter and all the other parts for less..

Here in San Diego, near the Mexican border with Tijuana, we have salvage yards full of square body Chevys. I got a quote from a Mexican shop, 1400 out the door for a junkyard replacement... I'm not even considering it, I have not had good luck with these places in the past. They give a 90-day warranty and you never know what you're going to get.

I went to my local gearvendors under Drive overdrive, and they started talking about $5-6k ...

 

[imiceman44]

Here in San Diego, near the Mexican border with Tijuana, we have salvage yards full of square body Chevys. I got a quote from a Mexican shop, 1400 out the door for a junkyard replacement... I'm not even considering it, I have not had good luck with these places in the past. They give a 90-day warranty and you never know what you're going to get.

I went to my local gearvendors under Drive overdrive, and they started talking about $5-6k ...

If you decide to downgrade to a non lockup let me know, I just took a recently built th350 off and put a 700r4 so I can give you a good deal on it.