Want to put in a T56, clutch pedal question.

[mike's1965]

In 2003-2004 I swapped what I thought was a 454 and TH400 into my 1965 C10, then for years dreamed of doing a LS swap after I found out my 454 was a 1968 C10 396 310 horsepower, because 396 doesn't have the potential of a 454 or 496 stroker.

Anyways, I've decided to just stick with the 396, LS engines are expensive, LS3 crate with accessories and ecm controller is 10K, not including a transmission. Used engines who knows how it runs/condition, and dealing with all the wire harness, fuel tank for injection, etc, the 396 with a new Magnum T56, I want the one with .50 6th gear ratio, with the 3.73 gears the truck has, should work good.

My truck originally had a 283 and powerglide, so there is no clutch pedal.

I sit in the truck and imagine where factory clutch pedal would go, and it seems it would be uncomfortable, I am 6'3 and have long legs, my right leg slightly folded in to push gas and brake pedals are fine, but left leg folded in is uncomfortable.

But maybe the clutch pedal doesn't have to be up as high or far out from firewall as brake pedal?

Anyone have pics of clutch pedal setups in a 60-66 that is hydraulic?

I want my left leg/foot to have more room, not pulling in upper leg, or bending lower part of leg at such an extreme angle.

[mike's1965]

Anyways now I'm over 40, I don't care about trying to have a high horsepower engine so much, and I already have the LS1 in my Corvette, so keeping the 396 big block actually seems cool, 10 years ago LS swap was so cool and modern, now it seems not that awesome.

I think the transmission will help a lot with freeway, or even in town cruising, and yes it is expensive, but I think this is one of those times where you get what you pay for.

Even if gas was free, no overdrive just sucks, and limits your speed, lots of noise from high rpm.

Hopefully the T56 will fit in the truck without too much floor massaging/cutting.

Another vote on T56 is it can work with pretty much any engine, if I do go LS or something GM modern V8 in future, a 700R4 would be hard to adapt to modern, plus those are not cheap either.

T56 is what I want and need. Truck will probably still eat more gas than if it had say a crate LS3 and T56, but $10,000.00 buys a lot of gas.

[bloo]

The hydraulic setup was only in a couple of years, I think 60-61? My 66 has a mechanical linkage with a z-bar. I am also 6'3". My 66 is a suburban, and the seats are mounted further back than they would be in a pickup. Yes, those pedals are too damn high.

The 60-61 (62?) hydraulic setup uses a weird combination master cylinder for the brake and the clutch. It would basically stick you with single circuit drum brakes. However, I have seen a kit advertised on here somewhere, probably from Captainfab, that uses a Wilwood clutch master and allows dual circuit discs and even a power booster if you want it.

Power brakes allowed a lower pedal in my 66, but the clutch is still stupid high. The floorboard is just too close. My clutch linkage is crap. It is made of allthread and god knows what else. I thought I saw a piece of curtain rod in there. It was not my doing. When I re-do it, I am going to alter the ratio somewhat and get that pedal lower. I intend to stay with a mechanical linkage, but hydraulic might make it easier. The thing is, the shorter you make the throw, the harder it is to push. I have a weakling low-compression 283, and I am going to downsize the clutch to 10-3/8" to help with that, but it seems to me with a big block you will need a big burly clutch and it might be pretty hard to push. Good luck.

[geezer#99]

You’re gonna spend a ton of money to find out your 396 isn’t gonna like that 6 speed o/d.
Easy way to find out is drive in high gear at 1450 rpm.
See/feel how that feels.
JMHO!

[mike's1965]

It's not currently registered or insured.

Is that a weak rpm range on these engines?

[geezer#99]

That’s a weak rpm on any gas engine unless it’s designed for it.
At that rpm if you put pedal to the metal nothing happens.
Just plain dead.
Don’t be afraid of rpm.
Most small and big blocks like to run from 2400 rpm or more.

[mongocanfly]

Mike...what size are your rear tires?

[bloo]

Generally speaking old carbureted engines don't like to cruise that low, even if they are stock and not built up at all.

What gears do you have now? They might be kind of high because it was a Powerglide? All I remember about the gears that were in mine when I got it (decades ago) was that they were ridiculously low. Probably 5.13 or maybe even worse. It could have used all kinds of overdrive. The 283 was screaming for mercy at 55mph.

I would do a little math and see what your RPM in high would really be in sixth, and fifth! Maybe fifth would be just right, and 6th would be for level cruising on 80MPH freeways? Maybe not. Worst case, maybe you change the rear axle gears?

EDIT: I missed in your original post that you have 3.73. Yeah, thats gonna be kind of high.

[Captainfab]

I make the hydraulic clutch conversion solution for those installing a T56 or other trans needing a hydraulic clutch. I make and sell a lot of these for the '60-'62, '63-'66, '67-'68 and '69-'72 trucks. IMO with 3.73 gears a OD trans would be nice behind a big block. You may not need 6th gear until you are at upper highway speeds.

http://www.67-72chevytrucks.com/vboa...d.php?t=651200

[mongocanfly]

heres a chart that will help you with rpms...www.csgnetwork.com/multirpmcalc.html
and im gonna guess you have a 28in tire
so
like geezer pointed out...
28in tire-3.73-.5od at 65mph youll be turning 1455rpm

same combo running in 5th gear (.85) will be 2444rpm at 65mph
I would think 6th gear would be near useless..you may want to look at just a 5speed trans...

[scottofksu]

Why not look at an NV4500? That’s not to say a T56 can’t be made to work, but you’ll have to adjust your tire height and/or your final drive gear ratio to make sure all the transmission gears are usable at rational speeds. Only shifting into 6th when you hit 90 is probably not so useful. I’m running a 383 and a t56 switched to hydraulics using the fine product Captainfab produces, and I’m changing up both the tire height and switching to 4.11 gears to achieve a 65 MPH cruising RPM of 2100-2200 - which is 300 rpm into the sweet spot of my engines power band. As with most things, it comes down to how much are you willing to spend to achieve some objective (I.e., running a T56).

This is all to say nothing about the potential need to rebuild the T56 and moving the shifter forward to the access port - mine needed both of these and cost me $2,500. Then you need to get a flywheel - mine cost $600 as I’m running a T56 on a 2 piece mainseal block - and find an 11” clutch that’ll hold your power. Not too long and your into some serious coin.

Deciding to run a 383 (built to the level I want) vs a 350 and a T56 (rebuilt and uprated with Viper internals) vs my 4-speed turned my engine and trans build into a $10k endeavor and I haven’t even touched the rear end which will need to be built to a higher spec given the engine and trans decision.

Not trying to break your heart! It’s definitely doable! Just trying to share my experience having had my heart set on a T56. Was it worth it? I’ll only be able to tell you once I get this thing on the road! It damn well better be! ��

[geezer#99]

Originally Posted by bloo

Generally speaking old carbureted engines don't like to cruise that low, even if they are stock and not built up at all.

What gears do you have now? They might be kind of high because it was a Powerglide? All I remember about the gears that were in mine when I got it (decades ago) was that they were ridiculously low. Probably 5.13 or maybe even worse. It could have used all kinds of overdrive. The 283 was screaming for mercy at 55mph.

I would do a little math and see what your RPM in high would really be in sixth, and fifth! Maybe fifth would be just right, and 6th would be for level cruising on 80MPH freeways? Maybe not. Worst case, maybe you change the rear axle gears?

EDIT: I missed in your original post that you have 3.73. Yeah, thats gonna be
kind of high.

In 6th gear with a 28 inch tire he’d be turning 1450 rpm.

[mike's1965]

Originally Posted by geezer#99

That’s a weak rpm on any gas engine unless it’s designed for it.
At that rpm if you put pedal to the metal nothing happens.
Just plain dead.
Don’t be afraid of rpm.
Most small and big blocks like to run from 2400 rpm or more.

My Corvette handles 6th gear just fine, it has the T56 with .50 6th gear ratio, and 3.42 rear gears, but maybe the LS engines can do what old engines can't?

I also never put the pedal to the metal in 6th or 5th gears, those are just for cruising along, I'll drop it to 4th or 3rd coming out of 6th gear.

[mike's1965]

Originally Posted by mongocanfly

Mike...what size are your rear tires?

275 60 15, however they are going to be replaced, I bought them summer 2002, probably drove 3000 miles tops moving from northern California to Texas, then from Texas to Phoenix.

So I can change them to something better suited if needed.

[mongocanfly]

Ok ...I just guessed at 28 in tire and that's what you got...
So the math in post 10 is correct

[mike's1965]

There is another T56 close ratio, 1st 2.66, 2nd 1.78, 3rd 1.30, 4th 1:1, 5th .80 and 6th .63, maybe it would be a better choice.

I liked the ratios on the wide ratio though, good for quick take offs, and low RPM freeway cruising. "wide ratio, 2.97, 2.10, 1.46, 1:1, .74, .50 WIDE RATIO VERSION great for everyday street use."

[mike's1965]

Originally Posted by mongocanfly

Ok ...I just guessed at 28 in tire and that's what you got...
So the math in post 10 is correct

Good guess!

[mongocanfly]

The .63 od will give you 1833 rpm with a 28in tire-3.73s-and 65mph...you could use the t56 if you really wanted...just not use the 6th gear....I've got a buddy with a t56 in his wagon...he said 6th gear is uselss..hes got 3.90 gears and cruises in 5th on the highway..

[mike's1965]

So old engines can't cruise at low RPM?

[bloo]

Maybe?

At 1450 RPM you'll be running mostly on the idle circuit and transfer ports, maybe a teeny bit of main. No power, and the enrichment will kick in with almost no throttle. The vacuum advance might start jerking your timing around. Everyone expected you not to do that back when carburetors were the norm. it might be ok, especially if you have a really tiny cam. or, it might be a bunch of bucking and surging.

Try it! It might be fine.

One thing that isn't obvious is that the RPM drop between shifts is gonna be about the same no matter what you do with the rearend gears. If you like the way wide ratio felt in some other car, you will probably like it here. If it is geared too high to drive right, change the rear axle gears.

All that would go out the window if you have, you know, a lumpy cam and a tunnel ram or something. In that case, close ratio is basically always better.

[mike's1965]

It might have a cam, probably pull engine out and replace gaskets, see what cam it has, before buying the new T56.

It has a Edelbrock Performer RPM Quadrajet that I'll be going through as well, it's too rich at idle, according to Qjet expert Cliff Ruggles, they put in big idle tubes to keep idle rich for wild cam, so I'll put smaller idle tubes in it.

So because it's a carb it can't handle cruising rpm under 2000 RPM?

I guess if it didn't work good, time to swap to LS.

[mongocanfly]

Even the LS isnt gonna like doing 65-70 at almost a idle...I've set my LSs/ratios to run around 2000-2200 or so rpm at highway speeds

[Clyde65]

What about an Lt L86 6.2/8 speed?

[TR65]

Mike,

Here is a link to how I added a hydraulic clutch for a T56 in my '65.
http://67-72chevytrucks.com/vboard/s...d.php?t=300087

I moved the T56 shifter location to use stock bench seat.
http://67-72chevytrucks.com/vboard/s...d.php?t=300892

Here is a link to my 6.0 LS2 with T56 install.
http://67-72chevytrucks.com/vboard/s...d.php?t=413880

I run 1800 RPM at 75 mph. The truck is very happy in 6th gear at 50 mph but of course it is not a big block. The overdrive is really nice for highway cruising, should be good with big block too.

I have run this combo for 9 years now. No problems except the shifter rod came loose at the attachment in the cab. Scared me but just required bolt tightening.

TR

[theastronaut]

Originally Posted by mike's1965

My Corvette handles 6th gear just fine, it has the T56 with .50 6th gear ratio, and 3.42 rear gears...

The Corvette is *slightly* more aerodynamic and weighs less. Aero makes a huge difference in how easily a car/truck can cruise over 55-60 mph. I drove from SC to AZ and back earlier this year and paid attention to cruising speed vs mpg. My car gets 40 mpg at 65-70 mph, 35 mpg at 80-85, and 30 mpg at 90 mph. It's geared well for the interstate, but it's shaped like a box and the added aero drag really makes the engine work harder with increasing speed. I added a cam recently that shifted the torque curve up a bit and it now it doesn't like fifth on the interstate with the A/C on, especially up hills- I have to drop back to fourth. So it's very possible to have too much overdrive in something that not very aerodynamic, especially with a cam that hurts low rpm torque.

I'd stay away from a NV4500 in a street truck, they shift like a tractor and aren't very fun to drive. We have one in a flat bed with a 454 and it's great for towing and does good on the interstate but the shifts are really clunky- not ideal for a fun cruiser.

A T56 would work well with 4.10 or 4.56 gears. Look into remote shifters with a high hump tunnel if you go with a F-body T56, that's a better option IMO than doing the internal shifter relocation. A Magnum T56 would have the forward shifter location already.

A little bit of rpm on the interstate isn't going to hurt anything. I grew up with early VW bugs that run around 3800 rpm at 70 mph. My old Miata did 4000 rpm at 80 in fifth gear. My Festiva does 3300 rpm at 80. It's not going to hurt anything to run some rpm on the interstate, your engine isn't "straining" or hurting itself from not having overdrive.