Trying to figure this out. Can I use a 1999 4L60E originally mated to a LS1 to replace my 1991 4L60 and bolt it to an ordinary L98? I can run it from my Fitech ecm but what about everything else? Bellhousing, crossmemeber, turbine, torque arm etc??

 

I asked that question to the www at large.
The result:

"Yes, you can adapt a 1999 4L60E (from an LS1) to an L98 engine, but you'll need an LS-to-early transmission adapter flexplate and spacer. The 1999 4L60E is compatible with the L98 engine's bolt pattern, but the flexplate provides the correct torque converter bolt pattern, and the spacer addresses any difference in crankshaft flange depth."

Seems to follow the logic of trying to do it the other way around. I'd investigated what's needed for an LS onto a 4L60 from a Gen 1 SBC application. In this case, the original Gen 1 style converter was to be used.
A flexplate or spacer was needed to account for the slight difference in the engine / transmission parting line. (IIRC).

 

Thanks. Hmm....I really don't wanna mess with anything except the swap itself. I can see myself bleeding, oily, tired and half beaten to death only to find out I need to change the flexplate because the installed aftermarket flexplate was wrong. Looks like I need to find an earlier 4L60E

 

I've got a couple of really knowledgeable transmission guys on speed dial. I'll see if can't get a definitive answer for you.

 

Champ!

 

I've yet to hear from my transmission people but in the meantime I found this.

https://www.speedwaymotors.com/LS1-L...ate,60449.html

If you scroll down the webpage they specifically address the "E" version of the 4L60.
Might be just the ticket.

 

Thanks but to me that flexplate seems to handle the opposite - how to mate an older transmission (TH700) to a newer engine (LS1). Am I reading it wrong?

 

You're right. That's the wrong link.
I DID find a Gen 1 SBC to newer transmission flexplate.
I'll have to look again. Somewhere my signals got crossed.
Sorry about that.

 

So, as it turns out, my transmission guy has never done this swap himself. Similar, but not the same so any input from him I wouldn't guarantee.
That said, what I'd thought I'd found, I can't find again.
It may not be of any help to you now, but once I'm back at my PC, I'm going to dig in a little further. If for nothing else other than my own curiousity. If something comes up in the meantime, I'll post here.

 

No worries at all. The match of a newer transmission to an older engine should be a popular modification. Especially when both the particular tranny and engine are the most produced parts ever. I'm surprised the www doesn't contain millions of links, parts and whatnot about how to piece them two together.

 

Funny you should say that.
I've come across a couple of posts and videos that discuss this. This one proved interesting (although I didn't watch it all).


He discusses the project and goes on to say rather than spend $300 on a "GM Performance kit", he proposes a DIY approach. But that he mentions a kit at all leads me to believe that there's something out there.

 

I just came across this:

https://www.onallcylinders.com/2023/...-chevy-engine/

I haven't read it entirely but the title matches the title of this thread.
Maybe there's something in it?

 

Interesting article. Too bad they talk about a slightly changed 2002 tranny. I think I need to read that article a few more times

 

Isn't your transmission a '99? Seems the only oddball would then be the one used for the truck iron block 6.0.

 

Ok, new plan. 94-96 Impala 4L60E. Sat behind a LT1. Should be less hassle, I hope.

 

Haven't bought the '99 tranny. Was just in contact with a seller.

 

I would think then that you're only concern would be a compatible flexplate.
See as your L98 is a 1 PC RMS and (AFAIK) so is an 90's era LT1, it should be straight swap.

 

I _think_ the flexplate is the same. That's no big investment anyway. Now I just gotta figure out how to get the old tranny out and the new one in without any major injuries.

 

No injuries indeed.
I've done the last half a dozen re and re's on my back in the driveway. I've taken one of my smaller aluminum floor jacks and built a crib to cradle the transmission pan. Nothing special. Just a slab of plywood bigger than the pan with some "shoulders" screwed to it to locate it. That in turn is screwed directly to the lifting pad of the jack.
At the very least, I have control over height and fore and aft. The angle is often difficult to get right but pulling the distributor and letting the engine tilt back as far as it can gets access to the bolts. As for the dipstick, that's a PITA unto itself.
My days of bench pressing a 150 lb 4L60 are long gone.

 

Oh, that cradle idea is brilliant! I will do that. I have another problem with tilting the engine - my Lingenfelter intake is kind of jammed into place and pressing against the wiper motor. I guess I have to let the upper part of the intake loose (as well as at least take the distributor cap off). Any tips on reinstalling or is it just a straight forward job?

 

Tips?
I'll lay out some of the difficulties and workarounds I've come across both recently and in the twenty plus years of doing this.
If you have a car lift it's a little different but if you're like me and doing this in the driveway or garage, the first thing is to get the car up as high as possible. The transmission on the jack with the dipstick tube in place makes getting it into location under the trans tunnel a task all of it's own. Last time, the rocker panel was almost 24" off the ground. I also remove the driver's side tire to get access through the wheel house. I have to come in sideways and the area of the wheel arch allows the bell housing to pass through. I did it once with the dipstick removed as it adds even greater height requirements. But trying to drop the tube in once the transmission is positioned is an almost impossible task.

Dipstick tube: See above but I'd have it installed and work towards getting up high enough. It's a choice between two struggles!

Engine tilt: The further back the better for bolt access. I also use a 3' long extension and a swivel 9/16th's socket. I also put a strip of electrical tape across the socket opening so as to provide a friction fit for the bolt. Saves me retrieving the dropped bolts a dozen times or more.

Cooler lines: Long ago I put together some AN flex lines about 18" long that hang off the transmission. During installation I don't have to access that confined space where the lines attach to the trans. That said, I don't use the stock routing for the lines. I've a transmission cooler in front of the rad and have plumbed hard lines into that. That AN to hard line connection is on the passenger side frame rail so access is ample.


The transmission before this current one. AN lines attached.


A prototype of the flexible lines before AN was incorporated.

That's about it although I'm sure something else will pop into my head about the install.

 

So, I've starting to tinker with this and first question is; can I change the "strut" from the older 4L60 to the newer 4L60E. There are clearly no castings on the E for hooking up the torque tube.

 

Yes.
The tailshaft / extension housing from the 4L60/TH700 will bolt directly to the 4L60E. Newer versions of the 4L60E have a 6 bolt housing whereas yours has the earlier 4 bolt version. This allows the torque arm to be attached.
FTR: I took a 4L60 from a 4 x 4 truck and fitted my 3rd gen 700R4 housing to it.
Double check the overall lengths between the two housings though to make sure there isn't some oddball version that you possess. As unlikely as that might be.

Alternatively, if you have the dollars, an aftermarket torque arm and transmission crossmember can be fitted which will divorce the torque arm from the transmission. Something recommended in high HP applications. High HP being relative of course. At ~450 HP and drag racing on slicks, I've yet to experience a problem with the OEM connection.

 

Thank you Mr. Z

 

Going forward. Got the thing out today.
I actually took the jack and pressed the tranny upwards, tilting it forward, which made it a little bit easier to get the two top bolts from above. Distributor cap was/is the only thing that had to come off. I could take the two bolts from the passenger side and not have to fight with the brake cylinder & booster.

Getting it back up will of course be harder.

 

I also switched the speed sensor thingy, from older gear driven to newer inductive. Back when I installed the Fitech (and scrapped the old ECM) I couldn't get the stock speedo signal to work with Fitech but solved it with a Dakota Digital SGI-100BT. taking a signal directly from the sensor. I'm hoping the DD also will solve this change of sensor.
I will also change the "metal linkage part" (me and words.... ) , where the shift linkage goes, to from the older to the newer.
I will put a corvette servo in the new.

I learned that:
1. Draining a tranny means there's A LOT of fluid left and it will spill all over you. It comes from the tv-cable hole
2. A torque converter is way heavier than it looks.

Question: Which torque converter should I use? The newer 94-96 sat behind a LT1. Could it possibly have a bit higher stall?