I just bought an 86 K5 blazer fully loaded. It has a bad transmission. So......Do I rebuild the 700r4 or put in a th350. My plans are for 4" lift, 3/4 ton, and 315s. What do you guys think??
CK5
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What to do?????????
- Thread starter 86454K30
- Start date
How much do you drive it on the street?
The TH350 is a cheaper and more reliable trans but will cost you a little more $$ in gas on the highway.
The TH350 is a cheaper and more reliable trans but will cost you a little more $$ in gas on the highway.
do you want overdrive? What gear ratio's do you have? 700r4 would be the easiest to do, since there is already one in there.
Slapperbar
Retired Navy NDT Examiner
Replace the 700 and put in a good cooler.
Nice K5.
Nice K5.
Wasatch K5
1/2 ton status
GM made some significant upgrades to the 700R4 in 1987 or 1988 (I can't remember which). Since then, they have also made improvements to the 4L60, many of which can be used on a 700R4.
Assuming it will be street driven, I would recommend a 700R4 over a Turbo 350 because of the economy advantages of the overdrive gear, and the lock-up torque converter.
But I would not rebuild a 1986 version. I would get a later 700R4 and rebuild that and use the upgraded components in it.
Assuming it will be street driven, I would recommend a 700R4 over a Turbo 350 because of the economy advantages of the overdrive gear, and the lock-up torque converter.
But I would not rebuild a 1986 version. I would get a later 700R4 and rebuild that and use the upgraded components in it.
Slapperbar
Retired Navy NDT Examiner
I think all of the goodies will work in an early case.
bolognablake
Registered Member
Clean blazer.
mudboggink5
1/2 ton status
I would go with the 700. I wheel with the 700 and have no problems. I like od 
bigbadchev84
1/2 ton status
DUMP THOSE RUNNING BOARDS!!!! Other than that nice blazer
Wasatch K5
1/2 ton status
One of the upgrades GM did was to the case itself. The later cases are stronger and are referred to as "rainbow cases" due to a rainbow shape in part of the casting.
jimbob91
Registered Member
Keep the 700.... Get a cooler....
DUMP THE RUNNING BOARDS!!!!!
DUMP THE RUNNING BOARDS!!!!!
Ok....I am pretty sure here is the plan. New 700r4, 4" lift(had it), 3/4 ton axles, and 315s on welds(gotta find the welds). Thanks for the input. Oh...and I took the boards off last night.
hmatiak
1/2 ton status
The newer cases are marked with a "K" on the outside close to the front of the case. If you get a core or another 700 built thats the case to go with.
Wasatch K5
1/2 ton status
The "K" cast into the case just means it's a 4X4 transmission case. The older cases had the "K" as well.
The "rainbow" cases have an arc on the right side of the case that looks like a rainbow. The arc is a slightly raised part of the casting and runs through the cooler line ports.
The "rainbow" cases have an arc on the right side of the case that looks like a rainbow. The arc is a slightly raised part of the casting and runs through the cooler line ports.
GMPP remans have all the updates and a warranty. That's how I'd get a new 700 if it was me, unless I was really trusting my tranny guy. I've heard too many horror stories of bad rebuilds.
Thunder
3/4 ton status
Thanks, Thunder, those guys are almost local to me and I didn't even know they were there. Reasonable prices, too!
Thunder
3/4 ton status
Yeah I can recomend them from personal experience. Bought a stage 2 from them over 5 years ago. Put in our wood hauling truck (91 k2500} We beat on it pretty hard.
Blew a 14 bolt but the tranny is still holding up fine.
Blew a 14 bolt but the tranny is still holding up fine.
Streetgliderx
1/2 ton status
sweet 86 mine is an 86 too and i have 4" and i also ditched the old man boards.. i have 350/700r4/10b/4.56/35" setup i run about 2300rpms at 65
this was her when i got her
this was her when i got her
Ok, 700R4 getting rebuilt as we speak, u-bolts for the lift showed yesterday, bought a set of new take off 315/70-17 BFG all-terrains($400!), running boards are history, picken up my 3/4 ton from my brothers next week!!
