VIPERSLYR

Hey guys this has prob been covered many times thinking of switching from my T-56 to a turbo 400 car has 373 gears use it as a street strip car. How are you liking the 400 for cruising on the street any input would be great TIA

mrvedit

Leave your T-56 in 4th gear (1.00 ratio) on the highway and that is what your TH400 would be like. Bet you would hate it especially with the otherwise-nice 3.73 rear.

SteenH

Best thing I EVER did was switch over to the TH400. It does rev higher cruising down the highway but no significant difference in mileage. Absolutely love my th400. Everyone has different ideas on tolerability. As far as driving around town etc it's better in every aspect in my opinion. Best of luck on a decision that works for you OP

tfi racing

iTrader: (2)

Exactly.It all depends on how and where you drive your car,a several hour long trip on the highway would be punishing with those 3:73's.You have the right idea,feel free to send that T56 to the west coast when you get sick of rowing through the gears...

forcd ind

iTrader: (7)

While a 400 is a great trans, I feel your going backwards in rem. an OD trans in this day and age-if anything, go to a 4L80E
I have been using the 80E's in the past few muscle cars I have built, the latest project I used a 400 due to space, and I can tell you I really miss the OD-not only OD but the lockup feature also.
In my 72 chevelle (6.0, Procharger, FI) I pulled down over 24 MPG on the highway, reduced engine noise, etc-expensive, but dam it is nice, lol

Won-Ton

You can enter your ratios and such and this site will calculate your cruising speeds.

http://www.grimmjeeper.com/gears.html

VIPERSLYR

Ya I guess there's pros and cons to everything I don't cruise the car as much as I use to more local and at the drag strip want the comsistentcy of the auto. I hear all diffrent things about the 4l80 swap to a f body some say it's a pian others say it's not to bad

RedRocketZ28

iTrader: (19)

The 80E is fairly simple and straightforward. I love the 80E in my car but I drive mine a lot when it's nice out. There's no way I would enjoy a TH400 with a 3.73 gear but like mentioned above, everyone has their idea of tolerability.

VIPERSLYR

How was the 80e swap to do is there a lot of pounding of the trans tunnel I've looked threw a lot of post but everyone says diffrent things. Do you use a manual valve body or what's controlling your shift points

RedRocketZ28

iTrader: (19)

There wasn't much pounding at all IMO. Mine is an early year 80E so it has the trans cooler lines upfront which makes it a bit easier as well. Did have to cut out a small section for the trans plug though.

Mine is ran on the stock PCM. I did a segment swap from HPTuners and very minor wiring (my car was a M6). There is the relay mod you can use as well to run it on the stock 60E tune though. There's a few threads on it here somewhere.

VIPERSLYR

Oh really so you can use the stock PCM also the ears did you have to cut them off, drive shaft and trans mount what was involved there. Thanks for the info

forcd ind

iTrader: (7)

I have seen a trans plug that is like a 90 deg, seems it would help fitment, just wire it into your harness

VIPERSLYR

Well decided to go 4L80 very strong and from what I have figured out with help from guys it's a fairly easy swap. Thanks

mrvedit

Good decision.
I think SteenH is different from most of us - I hear he shaves with sandpaper.

LS6427

iTrader: (2)

I just paid for a Stage 4 4L80E yesterday. That OD is going to be nice as well as full computer controlled up/down shifting.

The guy I bought it from told me about Speartech.

Speartech sells a 4L60E-to-4L80E plug and play adapter wire for the PCM issue. Plug it in and thats it.

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