4L80e transmission swap

[critter]

OOps!

Russ came over and we spent the morning tuning. He couldn't figure out why the thing needed so much throttle position to achieve a shift. Then he asked me about the carb. When I said Quadrajet the light went on. The small primaries require a lot of throttle position to achieve the same amount of "go" from the car. They don't tune much for Qjets. There you go.

I drove, he worked the computer and by the end of the morning he had it shifting pretty nicely. He had to pull the shift points WAY down because of the carb and torque of the motor. Then he said we needed to run it WOT a few times just to see what we had.

I still had the pressure gauge tapped into the transmission. On the second WOT it spun until 30mph (data logs are cool) and then hooked. It started hunting between gears so he had me get out of it. When I did, the pressure spiked and WOOSH! The pressure blew that hose off the fitting that went into the transmission. AT fluid hit the exhaust and we had quite a smoke show going.

The good news was that I was out of it when it let go and we just coasted down to the foot of the hill. I don't think I really hurt anything. I called AAA and had the roll back operator dump it back in the garage. I'll crawl under there, pull the remains of that fitting and plug it now that I know we're in pretty good shape on the tune. The I'll fill it back up with fluid and go again.

it's always something.


My snail trail:



The offending gauge:



I'll have a mess to clean up under the car:



Russell Culver from TCI was still tuning on it after the incident. Thanks Russ!:



At least I had time to make a photo of the car with the new wheels and tires while I waited:

[Vanmor]

Wow. I never thought about the carb. I thought it was all about the physical thottle position and torque of the engine.

The wheels really look good from that angle. Maybe I need to update too ?

That hose was a bit weak huh ? Hey it stayed together enough to get the data you needed. Glad you didn't have a fire !

Looks like your just about there. I bet it feels good.

[77TA]

Sounds like you had a profitable day and a bit of excitement... makes you think about puting the fire extinguisher in the car. I know I have forgot, but reading something like this drives the point home you just never know when something might blow out or leak onto something hot... Glad its coming together finally on the tune !!!

I am looking forward to next weekend !
Think the SD might be up to a little run through the cones by then ???


I think I got a exhuast leak...well more exhaust leaks lol... header flange leaks suck....
Manifolds are sounding better all the time....that or custom home made Tri-Y headers...

[critter]

Do you know me? LOL! I have an extinguisher in the car at all times. I have history with fire.

I doubt it will autox. That front end still needs a rebuild and the front tires need to be replaced before I do any spirited driving. Bummer on the leaks. That is why I switched to the manifolds. That and ground clearance were the motivating factors.

[Vanmor]

Are you guys running the cast iron Ram Air exhaust manifolds ? I hear they flow about as well as three tube headers which is what I have.

[critter]

Yes, I have the RARE 2.5 inch manifolds that have been ceramic coated. I do think you give up some HP with them but I'll sacrifice that for the ground clearance If you saw my driveway you'd see why I need that ground clearance. It's steep.

[Vanmor]

OK.......

So is the tranny in the Trans Am working like it should now ?

[critter]

It was until I dumped the fluid with the blow out. At least my oil leak didn't screw up the beaches or marsh lands. LOL.

I did get the fitting out and the plug back in. I wanted to rearrange the wiring and put the rear sway bar back on the car while I had it in the air. That's done. I still need to clean under there as well. Lots of fluid dripping off the bottom of the car but that's no big deal. I dumped in 2 quarts tonight and it's showing over full but that's normal with this Lokar dipstick. It takes it 24 hours to settle down and give me an accurate reading.

I might try to drive it again by about Thursday if I can stay on track with all the little things I have to finish up.

OH! The new tachometer is rock steady. Speedhut gets a huge thumbs up on customer service as well. Replacing the the bouncing tach with the new design just for feedback on how it works with the HEI is going above and beyond.

[Vanmor]

It's nice to know that some companies are standing by their products.

The new wheels and the overdrive should make it like a whole new car. Makes for nice highway cruising I bet.

This will make the paddle shifters work now.

[critter]

Cough, cough.

[critter]

I snuck out for a quick test tonight before the storms moved in. It was only to the end of the street and back but I have say that paddle shifters are the shiznit!

[critter]

So one more update on this project. Everything seems to be working well now except for my speedometer. I'm going to have to pull the dash one more time to try and resolve that. I have power to it but it's not acting like it's seeing any signal. The needle never moves.

I also would like to tweak the shift tables just a touch more to lower shift points. I will say that when it shifts in auto it shifts smoothly and having a 4th gear is the missing element I was looking for.

The paddle shifters are still new to me but they are more fun than a barrel of monkeys. I can't wait for a competitive situation to play with them

Was it worth all this frustration? Well...






Yes.

[critter]

So I'm back again.

I figure I need to deal with the lack of neutral safety switch and I'd also like to put a gear indicator light up on the dash for when I'm using the paddle shifters. So I was poking around on the Dakota Digital site and came up with the following products:

http://www.dakotadigital.com/index.cfm/ ... /prd60.htm

And:

http://www.dakotadigital.com/index.cfm/ ... /prd64.htm

So other than having another mess of wires to run, what do you think? That should get the job done, shouldn't it?

[critter]

But it just hit me that the gear indicator will only work if I can figure out a way to tap into the harness from the TCU. The gear indicator lever on the sending unit would not be moving while switching gears with the paddles.Doh!

[critter]

Since I got the TA back on the road I’ve been working to tweak out the shift points on the transmission. Once I got my head wrapped around the software it became pretty clear to me how the shift tables worked. Russ had set it up where most shifts were hanging on until 3000rpm due to the large amount of TPS angle the computer was seeing. He blamed it on the small primaries of the Quadrajet. All I know is that I’ve been building new profiles every day, making small changes and I’m really beginning to get happy with how it’s behaving. I SERIOUSLY flattened out the bottom end of the curve for the shifts on the 1-2 and 2-3 and it’s made a world of difference. The best part is that I don’t even get my hands dirty!

[Vanmor]

It seems to me that TPS angle is TPS angle. No matter what the size of the primary's are.

The Q-jet is a very unique carburetor. Maybe the fuel delivery is not as linear as it would be with a throttle body ?

[critter]

I don't disagree but the fact that it's seeing much more throttle angle than, say a Holley, for the low speed acceleration caused all his tables for tuning to be more aggressive.

I can say that I put my final tune in it last week and drove it on Sunday afternoon. It's just perfect for my taste now. I intend to hang on to some of the more aggressive tunes we did and figure out how to put that into second calibration available via the TCU.

[critter]

And what I hope will be my final update to this thread is this, I now have a dust cover over the converter. I never got satisfaction locally so I ordered one from PATC. I had to make an opening for the starter pinion since Chevy has it on th passenger side. I put a couple of small holes in the other side where it bulges out for the Chevy starter and ran a zip tie through to keep the transmission lines away from the exhaust and oil filter.

I hereby declare this a done project!