The 700R4 in my 87 IROC went south a few weeks ago, only had 1st and reverse gear. Since I bought the car about a year ago, I've had problems with the TV cable and always needing to reset it, as the shift points would change or go soft over time. I pulled the pan to see if maybe the tv valve was stuck, but when I pulled the pan, the fluid was more of less black, and I found a bunch of metal and what looked like needle bearings at the bottom (see pic). I decided then to pull this transmission.

I picked up another 700R4 out of an 86 IROC that had 38,000kms on it. I don't know the history of it, but was going to use it as a core for a rebuild. I've been doing a lot of reading and it seems though the 87 and up transmissions are the ones to build. I was worried that the 87 in my car might have damage to the hard parts and might not be worth saving. I guess what I would like to know is if the differences in the two are significant enough to see if i can reuse the 87, rather than the 86 one.

My car is not a DD, just a weekend toy. It won't see much 1/4 track time, but I would like to take it out to a few road coarse track days next year. The motor in the car is a 355 with a Holley Stealth Ram, Trick Flow G2 heads, LT4 Hot cam, exhaust etc. Running the stock 9-bolt with 3.27 gears. I'd like to convert to a 4th gen 10bolt with 3.73s in the future though.

Lastly, when it comes time to go with a converter for this build, I would like a 9.5" lockup converter. Would a 3200rpm stall be about right for this setup?

Thanks

Kevin

 

............... Thats a LOT of ugly in the pan ........ use the '86 core if it has an auxiliary valve body ... some later production units had 'em ... your '87 might have some case damage with that much junk in it ..........

 

The 1987-up 700r4's would be preferable. That year GM included a lot of changes to the 700r4 that the pre-1987 700r4's didn't get.

So long as the case on your 1987 unit is solid you can purchase all the parts that you will need from aftermarket vendors.

You could also go to an aftermarket vendor and purchase one of their transmissions & converters and send your current trans & converter in for a core refund charge.

The Holley Steath Ram intake is a good flowing intake up to around 6,000-6,500rpm. It has a lot more power on the top end compaired to a stock long tube runner TPI system. Stock long tube TPI motors can also extend the rev range out to that rpm buy using ported aftermarket components too along with head and cam parts matched to them as well.

3,200 rpm stall may be a little loose on the street. Typically you want to have the stall speed selected roughly 500rpm-700rpm below the torque peak of your engine.

I've got an L98 in my car with full bolt-ons; headers, high flow cat, cat back exhaust, custom cold air intake, ported BBK 52mm throttle body, ported Edlebrock base, ported SLP intake runners, and port matched stock plenum (with the stock block, heads, cam).

I'm running a level 3 Bowtie Overdrives 700r4 along with one of their 2,400rpm stall units. I've very satisfied with the stall that I choose. It acts like stock until you get your foot put in it. The car jumps in to the torque and power band and stays in that specific range until you back off. I'm still running the 2.77 gears and I still got very noticeable gains. Once you have a stalled automatic car you won't want to go back to stock stall. In these cars stock stall is around 1,600rpm-1,700rpm - thats great for fuel economy but not for performance.

I could have went with a little higher stall say something in the range of 2,600rpm-2,800rpm but that isn't necessary with a long tube runner set up which by design was set up as a torque based system.

For your car with the Holley Stealth Ram and Hot Cam set up 3.73's and a 2,800rpm-3,200 level stall should give you great performance. Your torque should peak in the early-to-mid 4,000 rpm range and your motor should easily rev out ot 6,000-6,500rpm with out a problem while still making good power.

Your rpms will be higher on the freeway with 3.73's but you need to those steeper gears since you will converting to a shorter runner intake system and other components designed to let the engine breath at a higher rpm than a long tube runner set up.

 

Use the 1988 and up if you are going to build a Street/Strip unit using the TransGo Perrformance Shift kit. The early 1987's still use the early (1982 - 1986) type 1 valve body which do not work with the TransGo Performance Shift kit. The late 1987's use the type 2 valve body which will work without any problems when using the TransGo Performance Shift kit. The later the better here.

 

Well i started taking the core apart to see what I had and the good news is that its not an 86 700R4, its one of the 87 up ones and looks identical to the one that is in my car now. Bad news is that as soon as I pulled the pan off the core, it was full of muck that at one point in time might have been transmission fluid. Imagine what slightly melted ice cream is like, and that was the trans was full of. It had a fair bit of water in it as well. I got the pump out and the input drum is very rusty. Not sure if its even worth going any further with this one as I am sure if the drum is rusty, all the other steel/iron parts in the trans will be in the same condition and garbage.