scottyp99

Hi, all!
I'm slowly gathering parts to do a 700r4 swap in my '80 'vette (currently has the stock th350) and am now trying to decide how I want to control the torque converter lock up feature. I am currently thinking of going with the TCI lock up kit:

http://www.summitracing.com/parts/tc...FdSj4AodlWQANQ

It seems simple, effective, relatively inexpensive, (if you can call 90 bucks for a pressure switch, a vacuum switch, a pan gasket and a couple of wiring pigtails inexpensive......man, somebody's making a tidy profit off these things!) and easy to do. But I would like to hear any input from forum members who have used this kit, or can suggest a better way to go. Thanks,

Scott

calwldlife

I thought 80 had a lockup 350?

hugie82

I'm not sure if the 80 lock up can be used in the 700R4 but I've heard good things about the B&M lock up kit.

v2racing

It all depends on how the tranny is set up. My Art Carr will only lock up in 4th. I just used a vacuum switch on it so that when I put a heavy load on it, it would unlock. Didn't have to worry about unlocking for stops because of the 4th gear only lock up.

My other 700R4 was built by a friend of mine and he did away with the electrics. He set the valve body up so it would lock up in 3rd and 4th automatically and unlock when you put the pedal down or coming down in the gears. It was really slick!

scottyp99

I believe that in '80, only California cars had the lock up. At any rate, my '80 'vette doesn't.

Scott

scottyp99

Additional question: My donor 700r4, (out of an '88 IROC) came to me with no torque converter, so I have no torque converter bolts. The 700r4 torque converter takes different bolts than a th350, right? I'm going to need something like this,

http://www.summitracing.com/parts/rn...make/chevrolet

and my '80 flexplate should just bolt right up to the 700r4 torque converter, correct? I'm pretty sure that's right, just wanting to double check with experts.

Scott

v2racing

No, I believe they all had them. My 80 was bought in Minnesota and lived it's life here. It had a lock up converter turbo 350C trans. If yours doesn't, it's been replaced with a regular 350 turbo.

v2racing

Yes, those will work. They are metric on the 700.

scottyp99

I think what I'm looking for is lock up in 4th gear only, disengagement when putting some load on the engine in 4th, and disengagement when hitting the brakes. Supposedly, this can all be provided by the TCI kit. One thing I'm a little concerned about is the fact that I have a 3.07 diff gear, and if lock up occurs automatically as soon as the tranny shifts into 4th, I may experience extreme lugging if the tranny shifts into 4th at low speed, say, just putting around town. I'd rather not have to keep it in 3rd gear when putting around town. Something that engages lock up at a certain speed may be what I'm looking for, not sure, that's why I'm asking for input. If you're using the TCI lock up kit with a 3.07 diff gear, I'd especially like to hear from you.

Scott

v2racing

With 3.07 gears you are going to have to shift down for around town. Depending upon your engine build you won't want to hit fourth with lockup until you are clipping along at pretty good highway speeds.

scottyp99

There seems to be a lot of controversy surrounding this subject. However, whether it was born with or not, my car does not have a TH350C now. And soon, it will have a 700r4, and that's what this thread is about. Thanks for the confirmation on the torque converter bolts, I am trying to get all of the little details taken care of so there are no surprises when it comes time to do the swap. I'd like to get it done over the course of a couple weekends. I know, I know, there's always something.......but I'm still gonna try!

Scott

scottyp99

I suppose I could live with that. According to an online calculator, my rpm at 60 mph should be about 1600 with lock up engaged. 1200 at 45 mph. That's pretty low! I don't see myself cruising at 60 on the highway, though. More like 80, which, according to the calculator, should be around 2150 rpm. So, instead of pushing a button, or flipping a switch, I'll be shifting into overdrive on the highway. Yeah, I guess I could get used to that. Most off-ramps have a stop sign at the bottom, or at least a yield sign, which should give me a chance to shift back into drive/3rd. My plan with the engine is to build for low end torque, so, I guess we'll just see how she drives, and go from there. I imagine if she shifts into 4th at 40 mph, a little gas pedal will shift her back down into 3rd. Anyway, tahnks for the input so far.

Scott

lionelhutz

You could put a B&M speed kit into it too so you set the minimum lockup speed.

This is where EFI and lockup converter or 4l60e trans really shine, setting the shifts and/or lockup right where you want them.

scottyp99

Yeah, but a 4L60E ain't in the cards. Workin' on a budget, here. I have a 700r4 out of an '88 IROC, and that's what I have to work with. My Dad used to say "Sometimes, ya just have to do the best you can with what you have." Do you have any experience with the B&M lockup kit?

Scott

qwank

what controls the lock up in a non CCC '80 Corvette then?

v2racing

The 350C in an 80 is controlled by a vacuum switch. High load, low vacuum and the lock up unlocks. It also has a switch on the brake pedal. Touch the brake pedal and the convertor unlocks. I used the existing switches to control the Art Carr when I had it in my 80. My Art Carr 700 only locks in 4th though. It wouldn't have worked as well if it locked in more gears.

terry82

I have the factory 700r4 in my 82 vette .it has a lower rear end gear than what you have .it does fine .

lionelhutz

Not personally, I went the EFI route and it controls the TC (and shifting). I've read comments from lots of other people who use it that seem to like it.

diehrd

Your motor will compensate for the high load low rpm by adjusting fuel delivery his will not. Usually if you have a carb and an O/D (with low gears) you are going to have some issues with lugging and bogging and I can get technical but at 1200 he is under such a load that when he attempts to accelerate it will fall on its face . ( At that rpm and speed he is making 30hp now try to go 65 casually ,, buck , bog and stutter she will go)

Almost all O/D mods to our cars are done because the rear gears are higher , 3.55 and up and we are looking to tame the rpm's on the open road. 3.23 may work but much lower then that and your into areas a carb was never meant to deal with.

All 1980 had lock up , the vac switch is located to the right of the break booster and it can be used on the 700R4 .

My advice is to put a 350 lock up back in her and you will get good gas millage and good drive ability with out any extra work. Or toss 3.55 and up rears in her.

scottyp99

if I were in 4th gear at 45 mph, at 1200 rpm, wouldn't the vacuum switch allow it to unlock, once you give it some gas? Or might the tranny shift into 3rd? Well, like I said, we'll see how it goes. Maybe a set of 3.55s could be in my future. Around how much do-re-me does a new diff gear run, price-wise?

Whew! Just crunched some numbers, and a 3.55 diff gear would give me an 10.86:1 final drive in first gear! Not bad. And, a final drive in 4th gear of 2.485:1, that would still let me rev at less than 2200 at 70 mph.

Scott