I Can't DRIVE....... 55!!!!!!

[Andrij]

Used to be able to do 65, & I thought I recalled 75, but since I've changed out my TH400, for another one (TH400) I can only do 43, & a really shaky 55. I'm sure I'll have to trade out the gears for one, but what advice do you all have to say to help me go over 55...
FYI, I have a 350 engine, Eldenbrok 1405 Carburator & Dual Intake Manifold, 10 bolt rear end. & everything else is pretty much stock. Thanks for any help!

[rage'nrat638]

soulds like you got the drive shaft in untimed...but we have no details..

truck type??
lwb/swb?
1/2..3/4?

[TugOwar]

Hello and welcome from South TX.

Maybe a dumb question but are you sure you're only doing 43 mph? Here is why I ask.
Unless the new trans came out of a vehicle with the exact same gear ratio and tire size as your truck, the speedo gear is likely different. You may be going faster than the speedo says. The gears are color coded, easy to check and see if they are the same or different.

[krue]

My truck is doing 75 when the speedo says 60 or so. Maybe you're going faster than you think. As far as the "shakey" part, what kind of shake are you getting?

BTW Welcome to the board from South Mississippi!

[Andrij]

68 Chevy C20 Truck. I know the TH400 has 3 gears & I'm basically out of gear. So the shake when your flooring the engine. I don't think my truck likes it, so I don't do it. TugOwar you have a good point, but I'm pretty certain the speedo is pretty close.
It has a 350 engine, Eldenbrok 1405 Carburator & Dual Intake Manifold, 10 bolt rear end.
I was just curious what people would advise in exchanging my planitary rings, or a different Tranny, as well as ratios for the rings or gears. Thank you for reading!

[Longhorn Man]

onless otherwise optioned, you should have a 4.10 gear in that sucker, and you should be able to do 100 MPH with no sweat.
I'm betting the shake you are feeling from the engine is a misfire.
When was the list time you did a tune up?

[MisterMan]

this is gonna sound really stupid... but, does it shift all times required... at what speed does it shift out of 1st at???

[E's c10swbfleet]

700r4 it has an overdrive 65mph turning 2300 rpms

[sbc383rulz]

if ya got 4.10's ya should do at least 100 mph topped out i can do 140 with my c2500 gmc and 4.10's read 6250 rpm

[Andrij]

Wow is it already 2010? (opposed to '06) Damn those Deployments really took a bite! (3 tours to Iraq)

Well I'm back, & getting out & I hope to have more time to spend with the truck! As for the old problem, haven't looked into checking the driveline's balance, can & have tuned up the engine, I'm currently rebuilding all four of my TH400s (output carrier removal issue in another thread) & I will eventually swap a TKO600 in over a 6 speed because after talking to alot of people, they just don't use the sixth gear, & since I like to pull stuff with my truck the torque it can handle will be there.
After doing alot of research through the forums I feel my problem is:
Transmission mount, I was too cheap at the time to buy a new one & it looked fine.
Transmission member not secure, a couple of the bolts securing it weren't completely tightened down.
Those caused transmission failure & the vibrations I felt, possibly even the motor mount is bad too.

Until she runs again, looks like I'll be driving the '69!!!!!! (C10)
I'd like to thank everyone for their comments & suggestions! & it's awesome to be home finally!!!!

[red71cheyenne]

Welcom home and thank you for your service!!

[oldblue1968chevy]

wow lol thread from the dead, welcome back and thanks for serving!

[67ChevyRedneck]

What a fitting day for your post. Welcome back and thank you

[Stocker]

Welcome back, and thank you for your service!

[tim21391]

i had a smiliar problem that many people on here probably know about... i wouldnt be able to go past 55.. like i had all the power in the world just when i hit 55 it fell flat on its face.. it happened to be my secondaires were stuck shut.. i know the 1406 is a 4 barrel i dont know about the 1405.. if its four barrel turn truck off and give push the throttle lever on the carb then push up your secondary lever if that dont open im guessing that may be it... just my .02.. i figured that was my problem and i fixed it and had it out doin 80 the other day just fine

[67chevy1series]

i would have to say that the transmission isnt good or you have a stall torq con. my brother had one and it had some trouble getting to speed but i would consider the 1406 edelbrock carb elecric choke

[tim21391]

ps who sings that song.. sammy hagar right? sry to get off topic

[Andrij]

It's certainly a pleasure to be back & your welcome, the freedoms we have is definately worth protecting & it amazes me the modern world around us that the people before us worked to create. In talking to old gramps, it's amazing the change from now, to the 90's to the world of yesterday.

Yup 'ol Sammy, if you ever seen the video

YouTube- Sammy Hagar - I Can't Drive 55

Gotta love that yellow jumpsuit with armbands & is he sporting a perm?

No kidding thanks for the tip about the secondaries... Easy enough, with all of the times that my trucks been parked for basically a years time I'm not surprised about that sticky old gasoline... My 69 is also the same way as my 68 (But it's odometer is non~op...), so looks like it'll be a two for one this weekend!!!

Ya I could go electronic with the choke, but there is something I like about this truck being mechanical, goes back to learning about chevys & the people before me... After I'm happy with the way the '68 runs I hope to do FI for the next build, so I can have both. Let me pull up an old story...

As per March 25, 2008
"The cost of gas is so high! I don’t know why you don’t just get rid of your truck & get something more economical."

Well, I love Viz, my ’68 C20 truck. Just today I’m filling her up with gas, & I go ’I’m going to have to put you on a diet, you’re drinking to much. Ha Ha Ha’ & this 1LT goes "you shouldn’t be talking to your truck like that, it’s not normal," or something like that. & I go, ’See that Viz he just wishes he had this kind of relationship with his piece of **** plastic SUV.’ I don’t think he finished filling up because he immediately put the gas pump away & drove off. I’m still laughing.

& in yahoo news (remember Mar '08) it is said that kids costs $204,060, which breaks down to $944.72 a month… hmmmm. During the work week if I was spending $15 a day on gas (hypothetically, with every day being a bad day since I spent $17 today driving all over post [or DaM's('69) fuel leak from Ms Holley]), it only comes out to $315… & I still don’t have to add on a vehical payment. But all around me, people sure enjoy making babies.

Maybe there is a method to the madness?


Maybe, but I’m sure it’s not Maybelline…

I hope I didn't make that too long... Or should I connected it with another post? Anywho have a good 4th of July all & thank you for all of the advice & comments!

[Andrij]

I'm currently thinking not having the kickdown switch hooked up has been the culprit all along... After all the vacuum operates WOT & the electricity operates the pump... at least that is my understanding.

Times change...
I started working on vehicles back in '00, & all of this information (written & video) wasn't as readily available, in fact alot of it was word of mouth. So one of the things I was told was I didn't need to hook up the kickdown switch, the TH400 originally didn't use them.
I don't know why I thought of it while washing the dishes tonight, but I did. So whenever I get my tranny back together, I'll see if I can go over 65!!!! I do hope this work, I've replaced my TH400 3 times. >2 years ago, it was all fine & dandy picking one up for like $40-$80. Now, jeeez why are everyone selling them for $325 (if you can find them) & up? Ridiculous...

[stsalvage]

my only question when you swapped the trans was that the only thing you did and all the stuff happened.Now i do have another ? so your going to a 6 speed stick Ok I know that a lot of guys don't have a lot of money with times being tough But do a little research On the Gear Vender it will do all the things you want it to do plus give you the pulling power and the Mileage per gallon Plus save your leg

[Andrij]

Thanks for the tip. Ya I've moved towards getting a NV-4500 someday, since I like having the option of pulling things. Ya funny how things turn out, returning to college, hard times I'm sticking with the TH400 for now, since back in 08 I bought 2 rebuild kits & at this point it doesn't cost me anything to rebuild...

[Andrij]

Ya, I know. Besides my truck being 3/4T, the TH400 was originally designed for dumptrucks.

[Boog]

Originally Posted by Andrij

Ya, I know. Besides my truck being 3/4T, the TH400 was originally designed for dumptrucks.

Thanks for your service.

Really? I've never heard that before.

[69heavychevy]

I have a TH350 but dont have the kickdown hooked up either...but i can still do 100mph+

[Boog]

Originally Posted by 69heavychevy

I have a TH350 but dont have the kickdown hooked up either...but i can still do 100mph+

That kickdown not being hooked up has nothing to do with it's top speed. It is merely the method of downshifting the tranny for passing gear.
If the truck won't accelerate past a certain speed you need to be looking for an exhaust restriction or fuel supply problem possibly. Also what rpm does it top out at?