4L80E, 74 TA, what to convert?

[critter]

I smoked the 1-2 shift on my TH-400 while drag racing this past weekend at Pontiac Nationals. I intend to long haul on the Hot Rod Power Tour next year. I have a deal on a 4L80E. What, besides the transmission cost, am I looking at for expenses?



Also, has anyone installed one of these in a second generation TA and what had to be modified to make it fit?

[myclone]

I smoked the 1-2 shift on my TH-400 while drag racing this past weekend at Pontiac Nationals. I intend to long haul on the Hot Rod Power Tour next year. I have a deal on a 4L80E. What, besides the transmission cost, am I looking at for expenses?

You'll need a control (aka PCM) to run the trans unless you go with a full manual set up. While Ive never converted an 80E myself to full manual my understanding is that once its converted it cant easily/cheaply be converted back to auto. Full manual autos can be a pain in traffic or just day in day out driving. A cheaper control is available from TCI but be aware Im hearing rumors that the price is going up due to an increase in the cost of their printed circuit boards....dunno for sure just what Ive heard from ppl that rub elbows with TCI. Cost is about $650 new and you can find them for ~$450 on fleebay every once in a while. The TCI unit is super user friendly for non computer guys but it does lack a bunch of bells and whistles that would make fine tuning a little nicer.

Compushift makes a control as well but its a little more pricey. You can buy them for ~$1200 directly from them or about $900 on fleebay. I only briefly got to mess with a compushift but it seemed like a more feature packed unit but it did require a little more gray matter to use.

I cant help ya on what else it would take to mate one to a Poncho but Im sure there are the needed adaptors to be had but it may take some searching.

[critter]

What searching I've done shows the controller being in the price ranges you mentioned. The other problem is manual speedo conversion. That looks like $500. If I did it I would use the "E" part of the equation. Why use old tech when the new tech is available? Two more parts have to be sourced, the shifter and the TC. The $$$ stack up in a hurry.

[critter]

One more, the adaptor to bolt up the tranny to a Pontiac block.

[myclone]

Torque converters can get expensive depending on what you plan to do with the car. The Coan tc Im using was about a grand but I wanted a quality piece that would stand up to several hundred ftlbs of torque and all wheel drive at the drag strip. Cheaper TCs are out there for a little more than half the price I paid but be aware that some ppl have had bad luck with them while others are doing fine.

The shifter shouldnt be a problem since all you need is a shifter thats compatible with a 700R4 or 2004R 4spd OD trans. If Im not mistaken I believe there are conversion kits available to convert a factory three spd shifter to a 4spd and look stock (if thats what youre after).

As for the adaptor I would thing there would be plenty of sources available as I would think it would be just a matter of needing something to mate the BOP block pattern to a chevy pattern.

BTW, what year trans did you get a good deal on? Reason I ask is the very early units require a harness upgrade and really should be upgraded with the later shift/pressure solenoids. The 97 and up units have a unique rear lube fitting that can be a PIA as far as clearance around the floor board once the adaptor fitting/line is installed.

[neki67]

The other problem is manual speedo conversion. That looks like $500.

There are several convertors available that convert the electronic pulse/signal back to a mechanical drive by means of an electric motor. e.g. from http://www.abbott-tach.com/cablex.htm $299.95. Or get an electronic speedo and splice the signal wire into the (TCI) computer harness.

And yes the $$$ add up quickly but the ease of tuning the gearbox is what pulled me over the line.

[Steve Chryssos]

Below is a link to a BOP adapter kit.
http://www.transmissionadapters.com/late_bpoc.htm

Controller:[/B] TCI makes a perfectly good controller that also carries the lowest price of the bunch. Powertrain Control Solutions has the best full featured controller. Retail price is $850. The harness is terminated on one end which results in a very clean installation, but you must turn your brain on to install and calibrate. One example of the software's power, you can set shift points in both directions (upshifts and downshifts). Here's a PCS feature for the SyTy crowd: Connect load sensors to both MAP and TPS and you can "trim" the calibration to vary based on engine boost. Have a tame map during vacuum and a firm map during boost. Pretty cool. I prefer to tune with a laptop, so the Compushift controller is not an option for me.
http://www.tciauto.com
http://www.transmissioncontroller.com
Shift Kit: A shift kit will help build mechanical pressure. From there, you can fine tune line pressure in the software.
Converter: Myclone summed it up perfectly--as usual.
Cooler Lines: Fitting selection depends on year of transmission case. If it's an early case, check these fittinng out as they consume less space. Russell 612000
Carb or FI: If you have a carbureted application, you will need to adapt a throttle position sensor. Both Compushift and TCI make easy kits. You calibrate the TPS sensor in the software, so there is no funky cable adjustment to worry about. Very easy.
Speedo I run an electronic speedo from Auto Meter. I caution you to connect and calibrate the speedo AFTER the trans install and calibration is complete. An uncalibrated speedo will confuse the TCM.
Calibration: I cannot stress how awesome it is to electronically calibrate the transmission to your exact vehicle specs and personal preferences. With a few keystrokes, you can literally change the personality of the entire vehicle. Once you've tried it, you will NEVER go back to a pre-electronic transmission. The calibration process is easy--way easier than say, fuel injection setup.
Installation: I have not done a 2nd gen BOP 4L80E install. Expect to do some minor hammering of the trans tunnel. Heating the area with a propane torch will make the clearancing easy. Of course, you will need to have your driveshaft shortened and move your crossmember rearwards.
Shifter: See Myclone's response.

[critter]

I didn't buy the 80E yet. Deal on the table has the price at $650. I'll have to check on the year. Thanks for all the input. I'll keep digging into it.

[71Formula]

I am just finishing the install of a 4L80E in my 71 Firebird (it used to have a TH400), and it is a huge project that gets very expensive very quickly. If you are not comfortable with fabricating your own metal parts, don't even think about this conversion.

To add to your list of parts you also need a throttle postion sensor (available from TCI) and any adapters/brackets required to connect it to your carb. You will also need to fabricate a transmission crossmember because no-one is producing one for this application yet. You will need to either buy a 4 speed auto shifter, or get a conversion kit for the factory shifter. You will probably also need to fabricate your own shift linkage, or modify one from a different transmission. You will also need to either purchase a mechanical speedo tailhousing, or a convertor box, or purchase an electric speedometer(my choice). You will probably need to run new coolant lines to the radiator (or modify existing ones I guess), I would also recommend getting an external transmission cooler).

Don't forget you will also need a laptop with a serial port to connect to the transmission computer.

I don't want to scare you away from the conversion, it is definitly worth the result (in my opinion). Me and a few buddies have put in nearly 80 man-hours into the conversion, and I still have to finish tuning it.

I plan to do a write-up that I will post on my little website whenever I get time, until then feel free to ask me any questions you need.

[critter]

Wow. So what about the transmission tunnel? Did it have to be altered?

Let me ask this question. There is a Hughes 700r4 with a converter in the newspaper today for $1,250. Anyone have any feedback on these transmissions?

[USAZR1]

Have you considered freshening up your TH400 and adding a Gear Vendors OD unit? Much easier way to go and just as strong.

[critter]

Considered and still on the table. That said, a 700r4 with a converter for just over a grand is pretty tempting. I called him tonight. It has less than 2000 miles on it. He had it in a street rod and has decided he needs to row the gears so he's put in a 5 speed. Going to go look at it on Monday night when he gets back in town.

[myclone]

Considered and still on the table. That said, a 700r4 with a converter for just over a grand is pretty tempting. I called him tonight. It has less than 2000 miles on it. He had it in a street rod and has decided he needs to row the gears so he's put in a 5 speed. Going to go look at it on Monday night when he gets back in town.

If you broke an even remotely healthy TH400 then a 700 will last no time unless you change driving habbits. TQ+traction+700R4=blown up 700R4. Ive seen street rod guys talk about how theyve had a 700 in their tubbed blown big block whatever but what most ppl dont realise is that 99.9% of the street rod crowd never even remotely get close to WOT/flogging their cars. Mostly all show and no go basically so yeah...a 700 will live behind a 1500hp motor if its only required to put up with three or four hundred of that hp due to being driven like a lil old lady.

If your heart is set on a 700 then by all means have at it since it will take minimal fabbing to install but be very aware that its not a matter of if it will break but when if you flog it regularly. Two or three performance rebuilds and youre not far from the price of what it would have cost to do an 80E in the first place...not to mention your time/effort removing the broken 700 then putting it back in.

[critter]

Agreed.

The 4L80E has proved too expensive for me at this time. I ran the numbers and simply can not swing the expense based on other modifications I need to make to the car to prepare it for the HRPT next year.

One of the reasons for being interested in this 700r4 is that I don't have to modify the transmission tunnel. I have a 1974 Super Duty Trans Am, a rare car. I don't want to alter the sheet metal for this project if I can avoid it. Another strike against the 4L80 and the GV unit.

So, my current line of thinking is to drop the 700r4 in long enough to do the HRPT and repair my TH400 while it's in there. I won't do any drag racing with that transmission in place and then swap back to the TH400 after it's repaired and I've finished the HRPT.

Also, my brother in law runs a performance and restoration business. Having accesss to a lift and transmission jack makes this job much less difficult.

[myclone]

One of the reasons for being interested in this 700r4 is that I don't have to modify the transmission tunnel. I have a 1974 Super Duty Trans Am, a rare car. I don't want to alter the sheet metal for this project if I can avoid it. Another strike against the 4L80 and the GV unit.

Ok, now it makes sense that youre looking at the 700 and I dont blame you a bit. A quality built 700 will do fine on the PT and put up with the occassional flogging on street tires. It'll even take small block tq on sticky tires for a short while but just be aware that eventually it'll need freshened up with new clutches/band (street tires) or at some point you may be the owner of trans parts that used to be one piece but are now multiple pieces (slicks).

If it was me before I wrote off the 80e completely I would procure an unusable/empty case from a trans shop (should be very minimal cash for a junk case) and do some fitting up to see if you can make it fit without metal surgery. There are several tabs/nubs cast onto the case from the factory that can be lopped off to gain clearance not to mention if an 80e will fit in a 4wd S10 with ZERO metal bashing Id think itd fit an F body with similar results. Thats just an educated guess though since I havent actually put one in an F body of any generation.

BTW/FWIW my favorite F body just happens to be the 70-73 TA and I actually had one that I was going to do the PT make over on....until I found out that you cant buy full quarters and tail pans which my car needed.

[71Formula]

Actually your fears of damaging the floors can be put to rest. I never made any mods to the tunnel in my 71 Firebird, which has the same floor as your 74. In fact if you could find an 90 degree elbow for the transmission line you would have huge amounts of room.

Just another comment about the price being to high for an 80E; try thinking over a longer period of time. My 80E cost me around $5000 to install (including a 1200hp capable rebuild), and I can expect to last me 20 years. If you choose the 700R4, how many would you need to install to last that long?

If you are not in a huge rush, I am working on a step-by-step guide with pictures for my website on doing this conversion.

Remember, if it is worth doing, it is worth doing right!

[critter]

Understand that, when the time comes, the 80 is a possibility. I have limited time and $$$ to convert my car from the current street/strip basher to a civil car capable of a 2000 mile round trip. I mean civil enough that my wife will be happy to ride along, which she will be doing. That means:

Gut the interior, insulate and sound deaden.
Fix all the leaking weather seal.
Decide if factory seats stay or get replaced.
Pull the big solid lifter cam and replace with a smaller, street friendly cam (might be hydraulic roller).
Re-work the exhaust system to gain some ground clearance.
AND put in some type of OD tranny.

One other option is to rebuilt the TH400, swap in a complete rear end with highway friendly gears, like a 2.56, and swap the rear end back after the HRPT. Lots to do and little time and money.

[myclone]

Actually your fears of damaging the floors can be put to rest. I never made any mods to the tunnel in my 71 Firebird, which has the same floor as your 74. In fact if you could find an 90 degree elbow for the transmission line you would have huge amounts of room.

Dunno if this helps any but if you end up with a 97 up case that needs the special do dad fitting this may help.


Link to page with part number and description...\/
http://www.transmissionspecialty.com.../34918-01K.htm

If you guys are running braided line/AN fittings there are several different fittings that can tuck things in close to the trans case.

HTH

[critter]

You guys have provided a lot of good information and helped me think this through. I want to thank you all for the help. Nothing is cast in stone but I'm seriously thinking along the lines of backing down the power level of this car, using the 700r4 and building a different car just for drag racing from here.

I was scraping the rubber off my car today, after three days of racing at Norwalk during Pontiac Nationals. The wife came out and pointed out that if I want to race I should build a race car. I love her!

So do you think the 700r4 will be OK with less than 400hp, street tires and around 500 ft. lbs. of torque and no drag strip time?

[myclone]

So do you think the 700r4 will be OK with less than 400hp, street tires and around 500 ft. lbs. of torque and no drag strip time?

On street tires a quality unit would prolly live a decently long life IMO just understand you probably wont get 100k trouble free miles out of it before it needs freshened up. Id go so far to say 40-50k of enjoying the car with street tires (enjoying=the occasional WOT blast/kick it sideways for a grin) then it may start showing some wear.

The rebuild kits for 700s are cheap its just when you really start hammering on the trans that it starts breaking the hard parts...which usually takes out a bunch of other stuff with it and that gets expensive quick.