Pontiac 455 + 4L80E = ???

[71Formula]

I am retrofitting a 4L80E transmission into my 1971 Firebird. Almost everything is ready to go, I just have a few questions I am hoping a transmission guru can answer for me.

1. Where can I find a flexplate that will fit on my Pontiac 455 engine, and mate up with the torque converter? The stock flexplate has only 3 mounting holes, and the 4L80E requires 6.

2. Will a factory stock 3 speed shifter still physically work with the 4 speed transmission or will I need to buy one designed for a 4 speed?

3. Is the slip yoke for a 4L80E the same as a slip yoke for a TH400?

[vintageracer]

Try "Shiftworks" for a detent kit that will allow the proper operation of your shifter with a 480LE.

[71Formula]

Thanks for the suggestion, I never thought about modifying the shifter I have, but it looks like that may work well.

[Jagarang]

Hmmmm....flywheel....opps.....forgot about that....better get on that little problem!!

I'll let you know what I find.

I have a 71 455 and 4L80E going into Eternity for the Power Tour. It's always the little things that screw up the completion schedule!

Thanks for mentioning this potential stumbling block!

[Jagarang]

See this thread...... https://www.pro-touring.com/forum/sh...ghlight=bowler

...and thank you Steve for the refferal.

I called Mark at Bowler and ordered an adapter and a pan for the 4L80E I'm putting into "Eternity". Now I need to find a neat way the shift that same tranny....hmmmm

I called Bowler Transmission, as suggested by Steve, and told them what I was doing and purchased their kit. I know that the tranny is mounted and in the car right now, but it's just for mock up. I'm not sure the flywheel and starter are in yet. I'll call Frank later today after he wakes up to ask about the "completeness" of what we got from Bowler is and get back to you. I hate to bother him "off hours" but this sound like a potential quagmire or trouble on the kind a schedule were on.

Maybe he'll read this post and I won't have to call him! I have my call quote to worry about! If he calls me, that a different story!LOL

Call me Frank....hehehehe

[71Formula]

I have now installed the 4L80E in my 1971 Firebird, and everything is working great. Thank you to everyone on the board who helped me with the project!

I just have one more question, it seems that the shop that rebuilt the transmission felt it wise to install a high capacity transmission pan; which would have been fine, but there isn’t enough ground clearance to allow such a deep pan on the Firebird. Does anyone know where I can get a stock, or even shallower pan? It seems everywhere on-line that sells pans for the 4L80E are selling high-capacity versions.

[andrewb70]

I have now installed the 4L80E in my 1971 Firebird, and everything is working great. Thank you to everyone on the board who helped me with the project!

I just have one more question, it seems that the shop that rebuilt the transmission felt it wise to install a high capacity transmission pan; which would have been fine, but there isn’t enough ground clearance to allow such a deep pan on the Firebird. Does anyone know where I can get a stock, or even shallower pan? It seems everywhere on-line that sells pans for the 4L80E are selling high-capacity versions.

Call up junk yards and get a stock pan. Or call the shop and get your stock pan back.

Andrew

[71Formula]

Call up junk yards and get a stock pan. Or call the shop and get your stock pan back.

Andrew

Actually that was the first thing I tried. All the junkyards around here can't keep the 4L80E in stock (it took me a month to get mine), and they aren't willing to sell the pans seperate from the transmissions. I called my transmission shop, but they already threw out the old parts.

[andrewb70]

Try these guys:

http://www.drichauto.com/

They show one listed for a 4x4, not sure if that will work for you. They are asking $65.

Andrew

[DeltaT]

I have a new, stock 4L80E pan I'll sell you for $20 plus shipping from 95051.

PM if interested. I pulled it off before I even fired the motor, and put a Hughes deep sump on there.

Jim

[Bandit]

Can we get some pics of your install? I was going to go this route before I decided on a TKO 5-spd, but I would like to see how yours is set up in case I go this route in the future...thanks

Paul

[myclone]

I have a new, stock 4L80E pan I'll sell you for $20 plus shipping from 95051.

PM if interested. I pulled it off before I even fired the motor, and put a Hughes deep sump on there.

Jim

If the above pan doesnt work for you (its a good deal BTW so Id try to snag it if I were you) there are usually quite a few stock depth pans on ebay at any given time. Youre local GM dealer is another source as well...just tell them what year trans you have and they should be able to set you up.

Which ever route you go if the pan you end up with doesnt have a drain plug then save yourself some messy grief and install one. I cut the drain plugs out of scrap oil pans and install them in the trans pan so that I only have to drag one size wrench under the vehicle to drain the oil and/or trans fluid. Its a little more work but MUCH better quality than some of the el cheapo bolt in drain plugs out there that leak or wont stay tight.

[critter]

So did it fit the 71 bird without modifying the sheet metal in any way? That's what stopped me (and the stupid high cost) the last time. If it will bolt in without cutting or altering the body, I'd like to know.

[71Formula]

So did it fit the 71 bird without modifying the sheet metal in any way? That's what stopped me (and the stupid high cost) the last time. If it will bolt in without cutting or altering the body, I'd like to know.

It fit better than I could have imagined! I never modified the sheet metal at all. I build a custom crossmember to hold it up, and it was good to go. I will post a few pictures, in a little while.

[71Formula]

Ok, I will post a few pictures for others considering the 4L80E in an 2nd gen F-body. Please ingore the rust, this is a daily driver right now, haven't had time to make anything pretty yet.

Here is the tranny on the stand.

Here is the mockup of the custom crossmember.

The transmission actually sits about 1.5" lower than the Subframe.

Here it is with everything installed

There is about 1" of space between the cooling lines and the original, unmodified sheet metal.

I am currently trying to design a crossmember to replace this one, that would allow sufficient space for a decent size exhaust system to be installed without loosing ground clearance. Let me know if there is any other angles or shots that would be useful.

[Bandit]

Thanks for the pics--good job on the install.
Did you have any other problems? What did you do for a driveshaft, and were you able to use your stock shifter? Is this an electronically-controlled trans or manual valve body?

Paul

[critter]

What he said.

Thanks for clearing up the issue of clearance. Now I know it CAN be done.

How much HP and how much torque are you putting to it? Is this a stock 4L80E?

[71Formula]

Thanks for the pics--good job on the install.
Did you have any other problems? What did you do for a driveshaft, and were you able to use your stock shifter? Is this an electronically-controlled trans or manual valve body?

Paul

It definitely can be done! This job did require some fabrication, I ended up building a new transmission crossmember (as seen), and the factory driveshaft was shortened to fit. I bent all new coolant lines (the th400 ones don’t quite reach). I couldn’t find any linkage that worked properly, so I build all custom brackets, and links.
I am currently using the stock shifter, it is technically functional, but the detent plate in the shifter doesn’t match the transmission, so it doesn’t work well. The shifter could be modified with a new detent plate, or simply replaced with a new shifter.
My 4L80E is electronically controlled with a box from TCI (I love this thing!). The transmission was rebuilt by a high performance shop to reliably take 1000 HP on the street, but at this time it is sitting behind a rather mild 455 pushing around 450 HP, 450 lb-ft torque.