Hey folks, I'm planning on doing my first transmission rebuild soon. I have a 1986 27-spline 700R4 sitting in my garage right now. It came out of my 305 Silverado with 175,000 miles or so, and it was still going strong, the truck's body basically fell apart on me.
Now I know that the 30-spline is better, but I also know that between 1984 to 1986 a lot of upgrades were made to the 700R4, only one of which was the increase in splines.

My first question is: How can I find out what was upgraded on my transmission from the factory and what was not?

My second question is: I'm planning on buying something like this along with a Corvette servo. Does that kit include any parts that were upgraded in the 30-spline 700R4s? (Besides the better clutches, bands etc)

My third question is: Would it be more cost efficient vs strength to go to a junkyard and pick up a 30-spline 700R4? (I'm on a tight budget, I'm hoping it's not)

 

What is your goal for this trans? Unfortunately an 87-up would be better and 89-up would be best. There were significant failure prone areas upgraded like the sunshell and 3-4 clutch pack. Some things are upgradable with your 86 core and some I dont believe are. Hopefully someone on here that has a little more experienced background will be able to answer that. IMO, there are better suited kits than the one you posted.

 

My goal is to have a strong transmission that will have no problems behind a mildly powerful 350 (250hp/330tq). It won't be used for racing at all, it's going into a work vehicle.
It's a 5000lb cube van that's sometimes loaded with up to 3000lb, so that's 8000lb total. Never used for towing.

I'm sure there are better kits, I just did a quick search on summitracing and came up with that, but I haven't really done any research into this yet.

 

it will hold up just fine as long as you make sure and hook up the TCC lockup wiring, also dont attempt any manual shifting for better performance. keep the TV cable adjusted properly. since you are going from a pickup to a van it was already setup for that usage.

 

Yes, I'll be hooking up the TCC wiring, I'm looking to get the most MPG I can because fuel costs my business $$$. That's why I'm swapping from a TH400 in the first place.

Any recommendations on a better rebuild kit? I'll be putting a Corvette servo in regardless of which kit I install.

 

an '86 v-8 should already have 30 spline input shaft. are you sure you counted the right splines? factory v-8 700r4's after mid '84 had 30 splines.

 

Yes I counted the splines right. It's in a Canadian truck, they were probably getting rid of the last of the 27-spline cores in Canada lol.