chases7885

I swapped out the stock trans for a turbo 400 in my 82 z28. It runs and drives its just not what i thought. I'm guessing its due to no over drive. So my question is is there another trans option that is as reliable as the turbo 400 but with over drive or a 4th gear that isn't electronic shifted or is there something i can do to the 400 that wont have my engine screaming at 50 mph like its going to drive right out of the car? lol Any help would be greatly appreciated

Tootie Pang

iTrader: (2)

What rear axle ratio are you running?

chases7885

just the stock rear that came with it in 82. Everything on car is stock except Trans and engine.

GeneralDisorder

iTrader: (1)

What RPM are you running at 50 mph?

GD

Kingtal0n

700R4 have overdrive and good for stock engines
4l60e is the 700R4 but with computer control for 1999+ engines also factory

TH400 is a strong 3-speed with NO overdrive
4l80e is the TH400 with overdrive. This trans is very heavy and will reduce fuel economy significantly over the 700R4/4l60e. It is intended for cars making over 500horsepower.

It sounds like what you need is a 700R4 for a stock engine. It is weaker and lighter than th400/4l80e but stock units will handle 300~hp usually if treated right.

RBob

iTrader: (1)

Sounds like the TH400 isn't up shifting into 3rd. As IIRC, an '82 didn't come factory with an overdrive trans. It was either the TH200C (auto) or the 4-speed T10 (stick).

If it isn't shifting into 3rd the vacuum modulator may be bad, or the electric kick-down isn't wired correctly.

RBob.

Orr89RocZ

iTrader: (20)

sofakingdom

iTrader: (1)

MILLIONS AND MILLIONS of cars and trucks came with a Turbo 400 and anything from 2.41 to 3.73 rear gears. I have just such cars sitting in my driveway & garage (74 Caprice convertible 454/400/3.42 now, and 69 Chevelle SS396 convertible 396/400/3.73 original) Millions more came with Turbo 350s, C-4s & C-6s, 904s & 727s, and so forth. We all did just fine back then. Granted, expectations were a bit different, but just the same... it's not like having your sheet metal pushed into a newer shape, somehow affects the trans/motor/gear combo behavior.

As said, first thing to do is, make sure it goes into high gear. With a typical 3.08 rear gear, 60 mph should be right around 2300 RPM. 2600 or so with 3.42.

Check the accuracy of your dash "tach" against a piece of actual test equipment. The factory wavy-pointer thing is just a "sporty image" trim package, not an actual "instrument" (the name of the cluster notwithstanding), and is NOTORIOUSLY inaccurate. They fail - ALL of them, EVERY LAST ONE - by reading high. I've seen them read 3 to 4 times the actual RPMs.

Kingtal0n

Even with automatic overdrive, the difference in economy savings between a sixth gear manual is significant
That said, nobody should be stuck in 1:1... its 2019, you drivin this thing?

chases7885

Thanks for all the response. I'll be able to take a better look when get it back from the paint and body place

tater

iTrader: (10)

Are you sure it is going into 3rd gear? The best way to set the shifter cable is to put the shifter in drive AND the trans in 3rd gear. Then lock down the cable.

If you tightened it down with both the trans and shifter in PARK, it might be manually holding the trans in 2nd gear.

427seven

I've looked over this thread a couple of times, and in your starter you said you did the swap. Did you do it yourself? Did you do the engine and trans at the same time? I still can't see anywhere that you've confirmed that your gauges are working and you know how your car speed and engine speed correlate with your gear ratios. These are things you have to know, as well as if the engine is running properly. Sometimes if you do a double swap like this you end up with compounding problems. Get one working right, then it's easier to drill down on the remaining problems - if they're still there... The turbo 400 is an awesome tranny, and if you really do have stock gears in the car, it wouldn't be that bad on the highway.

427seven

.....unless you feel the need to "cruise" at 100...

//<86TA>\\

iTrader: (14)

FWIW, I drove a 78 bird 3 and a half hours back to my house from upstate NY a few years back. Th400, 4:10 gears and stock size tires. Even at highway speeds it was not unbearable.

chases7885

I did do both engine and trans at the same time. I drove it the other day and it was running 3500 rpm and my dad following behind me said we were at 65 and 70 down the highway. The speedometer was jumping between 45 and 65 so I think it's broken. I've had this car since high school and something just feels like working really hard to just go 65 mph. Still waiting on paint and body to be finished so I can do other adjustments

chases7885

Yes I feel it shifting I to 3rd

chases7885

Yes it's going back to be a daily driver again.

chases7885

I have been considering changing the rear end but don't understand gear ratios. What gear do you guys suggest for a daily driver with a stock torque converter

427seven

A nice compromise gear is something in the 3:40's or 50's, too bad you don't know what's in it. Do you know that the Trans builder is reliable, who installed the TC, was it oiled properly when it was installed? Was the car surging at all while this was happening? 3500 at 65mph doesn't sound like third gear with a stock rear end.... An easy way of checking is counting driveshaft revs against rear tire revs, if you have a LSD. I have a GVO TH400 and in 5th gear (same as 3rd w/oGVO) at 3500 I'm doing 73mph with a 3.75:1 rear end. So unless someone shortened your gears from stock, or your torque convertor is slipping way too much, that's too much rpm for that speed.