NewbVetteGuy

I'm hoping that some folks on here can do a sanity check on my plans to do a 4L60E transmission swap in my bone stock (except for exhaust and gas shocks) 1979 L82 auto.

As my forum name says, I'm a newbie to cars in general, Corvettes and the forum(although I grew up around a huge GM/Corvette gear head and some of it may have accidentally rubbed off). I've been trying to learn as much as I can over the past 45 days so don't assume that I know or understand anything, please.

I'm looking for help on the parts list, my general plan and details on the steps involved although I'm enlisting professional help for most of the work.

I understand that the 4L60E is the same physical size as a 7004r/700r4 so it'll require a little denting of the tunnel with a mallet around the passenger side to get it to fit properly.


Parts List

• Rebuilt and "Hardened" 4L60E 98-05 version (stage 2 TransDepot)
• Appropriate Torque converter (I have no idea what stall speed to use ATM and don't understand the difference between a neutral balance and counter balance torque converter or which one I should get) -I've got true duals, no cat exhaust, low restriction mufflers and McJack shorties are going on it soon as are AFR heads and probably a mild EFI-appropriate cam)
• 700r4 Cross Member from BowTie (Assumption: 700r4 cross members are identical to 4L60E cross members as the trans are physically identical. (I'm assuming that this is why BowTie doesn't actually list 4L60e-specific cross members.
• Cut and balanced drive shaft to accommodate longer transmission or an aftermarket aluminum drive shaft (anyone know a reasonably priced source of driveshafts that would work for this conversion?
• Drive shaft yoke??!? -I'm fuzzy on this part; I can't reuse the existing yoke from my TH350, right? where do I find the right yoke and what is it called?
• Gen1 SBC Conversion Kit (to support connecting the 4L60E up to the L82); I'm VERY fuzzy on this. TCI seems to call it a GM Transmission adapter kit/ flexplate. They have two options GM Transmission 6 hole crank and 8 hole crank; I heard that GM actually makes and sells one but I can't find it. I'm pretty confused on exactly what I need here. HELP!
• EZ-TCU from TCI for electronic transmission control (apparently there's newer and older versions of these and the first version doesn't automatically shift the transmission into 1st gear at a stop.) I see them on CL and Ebay from time-to-time and I'd love to save some money by buying a used one but I don't know how to identify the newest model....
• Throttle Position Sensor- from TCI $137.50 comes with the bracket for my Qjet carb in the box. I'll only need this for a couple of months because in December I'm doing an EFI conversion but I can put it on CL then.
• Speedometer Control Unit- NO WAY. Way to expensive given that I'm doing a TBI EFI a couple of months later. I'll rely upon my GPS unit as my speedometer in the meantime.
• Shiftkit from Shift works- technically unnecessary unless I want to be able to keep it in 1st gear and even then I could just grind a detent in the existing shifter assembly but I want this thing to look "right" and like it came with a 4 speed.
• -edit- Shiftworks got back to me and provided a good tip for anyone doing this conversion that some 4L60es and 4L80es can have a long cable or shaft linkage and may need one of these for proper mounting, too. http://www.shiftworks.com/4lx.htm

Obviously, the "conversion kit" to connect a 4L60E to a Gen1 SBC is where I'm the most confused and need the most help; along with the details on the driveshaft and yoke, but is there anything I'm forgetting?

-The BowTie cross member comes with the bracket to move the ebrake cable so I should be good there.

Is the trans tunnel in 79 Vette metal such that I can just hammer a dent or two in it to make room for the 4L60e? -it's not fiberglass, right? (Figured I should explicitly ask.)



Thanks, everyone!

Adam

NewbVetteGuy

I'm also wondering what to do with the old TH350, cross member and drive shaft (if I decide to just buy a new one). This is a single owner 79 L82 all numbers matching everything car that my parents bought new in 79; the whole car trans included only has 14,900 miles on it so it's got to be worth something to someone trying to restore their Vette to proper factory shape, right?

Should I hang onto it in case a future buyer (if I were ever to have to sell it; hope not) wanted the original number matching trans?

-I plan to give this the resto-mod treatment so it won't be staying all original at all anyway (I think I'd cry if I had to keep these heads on this car. I feel like this poor L82 was given a lobotomy by smog regulations and deserves a set of AFR heads after suffering for almost 40 years; lol!), so my initial gut reaction would be to find a home for the TH350, cross member and drive shaft for someone who's trying to restore a C3 back to its factory state.


Adam

NewbVetteGuy

SBC 4L60E Conversion Kit
Update: Answer: Jegs got back to me and the kit not only includes everything I would need for this; it includes too much because I can't even actually use the included flex plate and need to reuse my L82's existing one. Now maybe I can find the other parts separate from the kit so I don't have to even buy the flexplate...

I'm slowly getting some details on the SBC Conversion kit. Here's the GM Performance item listed on Jegs; can anyone help me make additional sense of it?

http://www.jegs.com/i/GM%20Performan...0002/-1?CT=999

My understanding is that the kit includes a spacer between the trans bell housing and engine mount point. It then says in the details that "You will require an older style flexplate if installed on a two piece style rear main seal small block engine..."

From what I can find anything older than 1986 used this 2 piece seal so my 79 will require the old-style flex plate. This should be what's currently on it so they're essentially saying "don't use the flexplate included in the kit; just use your current old-school 2 piece flex plate"- right? Jegs says "yes; reuse existing flexplate"


Our engines use a 298mm shaft and the 98-05 4L60Es use a 300mm input shaft; does this kit somehow deal with this issue? Jegs says there shouldn't be an issue with shaft diameters.

Do I have to use a special torque converter because I'm combining the newer 4L60E with my Gen1 engine? Jegs said just use whatever torque converter I'd normally use with the transmission (I'm pretty sure that meant that this was a dumb question).

This part is so confusing...


I also read not to use LS motor bolts because they're metric and the Gen1's gonna be US thread; I'm assuming the kit comes with the proper bolts but I'll double check before screwing up the threads.


Adam

NewbVetteGuy

Sorry, folks I don't mean to be a spammer; this helps to capture any/all concerns as they come up in my planning and I hope this to be of use to someone in the future with similar plans.

My next question is regarding "PWM" vs. non-PWM versions of the 4L60e; what the heck is this and does it really matter if I'm buying an EZ-TCU to control it? Can't they control both PWM and non-PWM versions?


Adam


I realize that this isn't a C3-specific or even a Corvette specific set of questions and concerns; if anyone can direct me to a more appropriate forum I'd happily take any referrals, too.

NewbVetteGuy

Ok.. Crap...

I think my decision to use a 98-05 4L60E is just going to overcomplicate things. -Since I have to use the GM Performance spacer, that means that a standard replacement driveshaft isn't going to work and I'm just going to have to get the stock one cut, right? (I think so; not a huge deal, though)

The spacer also means that a standard 700R4 cross member isn't going to work either, doesn't it?!?


@#$@#$@#, @#$@#%@#^, #$@!^!@$$!!!!!!

I heard that each successive generation of 4L60E was better and better and in particular that the 1st gen 4L60e were super weak so I've been all excited to find a very low mileage used 98-05 4L60e that's had all the internals replaced to 4L65e specs, but now I'm getting second thoughts...


Adam