66 Newport T56 Swap

Ben Herman

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Bloomington, Indiana
I finally pulled the trigger yesterday and picked up a Viper T56 with the .5 OD. I've been chasing efficiency and high speed for a while so this was the obvious choice as soon as I heard it existed. There seem to be plenty of options for hooking a T56 up to a big block but I'm interested in what folks have tried and how it has performed. Before anyone gets too upset about me cutting up a car this one is plenty rusty and anybody restoring it would need to cut up the flloor and tunnel anyway to replace the swiss cheese floorboards. The car has 242k on it and I can't bring myself to go to all the effort of swapping a trans and still having an automatic afterwards.

What I'm looking for more than anything else is pictures of one being installed. I'll obviously have to cut a substantial amount of trans tunnel but I'd love to see just how much.

Should I swap to a short throw shifter since I'll be adding a rather tall shifter compared to the viper setup? I'd prefer a "truck style" no frills shifter and I'd like to be able to shift without smashing the dash and preferably the center drawer when its open.

Current equipment:
Mostly stock 383 with a FiTech on it. (Don't buy a FiTech. Mine is currently behaving wonderfully though.)
I have a few 440s and one of them is going to end up in the car someday soonish.
2.76 diff. I know this is the slow gear. I know that will make a .5 overdrive ignorantly silly. I said fast, not quick.

IMG20220517200729.jpg
 
I finally pulled the trigger yesterday and picked up a Viper T56 with the .5 OD. I've been chasing efficiency and high speed for a while so this was the obvious choice as soon as I heard it existed. There seem to be plenty of options for hooking a T56 up to a big block but I'm interested in what folks have tried and how it has performed. Before anyone gets too upset about me cutting up a car this one is plenty rusty and anybody restoring it would need to cut up the flloor and tunnel anyway to replace the swiss cheese floorboards. The car has 242k on it and I can't bring myself to go to all the effort of swapping a trans and still having an automatic afterwards.

What I'm looking for more than anything else is pictures of one being installed. I'll obviously have to cut a substantial amount of trans tunnel but I'd love to see just how much.

Should I swap to a short throw shifter since I'll be adding a rather tall shifter compared to the viper setup? I'd prefer a "truck style" no frills shifter and I'd like to be able to shift without smashing the dash and preferably the center drawer when its open.

Current equipment:
Mostly stock 383 with a FiTech on it. (Don't buy a FiTech. Mine is currently behaving wonderfully though.)
I have a few 440s and one of them is going to end up in the car someday soonish.
2.76 diff. I know this is the slow gear. I know that will make a .5 overdrive ignorantly silly. I said fast, not quick.

View attachment 572496
2.76 us not a slow gear. I would still be running mine if they made a fine spline pinion in 2.76 for a 489 rear center section (necessary for a 1350 size u joint yoke). My car was a tire smoking monster off the line and an absolute rocket with them. I liked them with the stock 440 and later with my 505 stroker.
 
2.76 us not a slow gear. I would still be running mine if they made a fine spline pinion in 2.76 for a 489 rear center section (necessary for a 1350 size u joint yoke). My car was a tire smoking monster off the line and an absolute rocket with them. I liked them with the stock 440 and later with my 505 stroker.
I already have people telling me I won't be able to use 6th and that I'll just stall it trying to start every time unless I find the weakest clutch available. I get blank stares when I remind them my 1st will be deeper than an a833 1st. 6th will be perfect for cruising without spinning the engine stupid fast all day.
 
If you do swap to this transmission I would suggest you also swap to a 3.23 or a 3.55 rear. Utilize the OD and also have off the line performance.
 
If you do swap to this transmission I would suggest you also swap to a 3.23 or a 3.55 rear. Utilize the OD and also have off the line performance.
I'm not really interested in burning rubber or stoplight racing. I am interested in how far I can stretch 25 gallons of gas across Kansas. I'll eventually end up swapping to a Dana60 for cheap rear disc brakes so I'll have to bump to a 323 if I remember correctly. I still haven't decided if the Dana60 is worth losing the 2.76 though.
If I actually have any trouble with rpm being too low I'll throw a truck cam in it before I swap gears.
 
Swapping gears in a 8.75 is a lot easier than changing the entire rear.
Swapping gears in the 8.75 would get me the gears I don't want and still no disc brakes. I won't be swapping away from 2.76 unless I am already swapping to a Dana60 because the Dana60 doesn't have any gear taller than a 3.23. If a Dana60 2.76 was available I'd get that.

I'm really not here to argue if my gearing is a good or bad idea. I can go to any car club meet to listen to people tell me I'm "doing it wrong" building something with a different goal than the usual. They usually quiet down after they watch me hit 115 in 2nd.

I want to see what I'm going to have to cut and see what clutch, flywheel, and bell housings people have used and how they like them.
 
Scarebird makes a rear disc conversion for our cars, or a least they used to. I have been happy with their front disc kit on my car. (You do have to use 15" wheels minimum)
 
Swapping gears in the 8.75 would get me the gears I don't want and still no disc brakes. I won't be swapping away from 2.76 unless I am already swapping to a Dana60 because the Dana60 doesn't have any gear taller than a 3.23. If a Dana60 2.76 was available I'd get that.

I'm really not here to argue if my gearing is a good or bad idea. I can go to any car club meet to listen to people tell me I'm "doing it wrong" building something with a different goal than the usual. They usually quiet down after they watch me hit 115 in 2nd.

I want to see what I'm going to have to cut and see what clutch, flywheel, and bell housings people have used and how they like them.
Are there roads where you live that you can do those speeds safely? There are more than one company making disc brakes for the 8&3/4 rear. They were used in Nascar back in the 60's so it should be fine. Have you beefed up the suspension?
 
Are there roads where you live that you can do those speeds safely? There are more than one company making disc brakes for the 8&3/4 rear. They were used in Nascar back in the 60's so it should be fine. Have you beefed up the suspension?
I plan to go with Firm Feel stuff for suspension. I haven't decided quite how stiff I want to go on the torsion bars as its a bit of a crap shoot trying to compare it to 50+ year old worn out ones. I certainly wouldn't mind it cornering a good bit better but need it to be soft enough to drive 14 hours straight and still have a girlfriend when we get there. The reason I was leaning towards Dana60 over buying parts for the 8.75 is that it will likely be cheaper at the end of the day and its tougher if I ever manage to get enough power up front. I'm not really dead set on swapping it if I find a conversion kit that doesn't break the bank.

As far as safety goes an empty road is an empty road. I make sure to not be an *** around others. If I run off the highway at 70 or 140 the result will be the same.

This swap is first and foremost me wanting a manual. Overdrive is an efficiency endeavor along with the fun of having unlimited top end. I expect to see 6th maybe 5% of the time I'm behind the wheel. I doubt I'll ever see 5th off the highway.
 
I plan to go with Firm Feel stuff for suspension. I haven't decided quite how stiff I want to go on the torsion bars as its a bit of a crap shoot trying to compare it to 50+ year old worn out ones. I certainly wouldn't mind it cornering a good bit better but need it to be soft enough to drive 14 hours straight and still have a girlfriend when we get there. The reason I was leaning towards Dana60 over buying parts for the 8.75 is that it will likely be cheaper at the end of the day and its tougher if I ever manage to get enough power up front. I'm not really dead set on swapping it if I find a conversion kit that doesn't break the bank.

As far as safety goes an empty road is an empty road. I make sure to not be an *** around others. If I run off the highway at 70 or 140 the result will be the same.

This swap is first and foremost me wanting a manual. Overdrive is an efficiency endeavor along with the fun of having unlimited top end. I expect to see 6th maybe 5% of the time I'm behind the wheel. I doubt I'll ever see 5th off the highway.
I had Firm Feel do my steering box. They tightened it up nicely and were nice people to deal with.
 
80 mph with 2.76, .50 OD and a 28" tire is 1325 RPM. I'm not seeing any stock stroke 440 delivering enough torque or horsepower at that RPM to hurl 4000+ lbs of Cbody through the wind at 80 mph never mind getting anything that resembles efficiency in the MPG department. I doubt a 5.9 Cummins could pull that off.

Kevin
 
Scarebird makes a rear disc conversion for our cars, or a least they used to. I have been happy with their front disc kit on my car. (You do have to use 15" wheels minimum)
Looks like they don't make them anymore for this application. Their Mopar section is a bit bare. I have a SSBC kit on the front and had a pretty terrible experience with the company. I got a box of parts that didn't fit together and since I was an 18 year old student at the time I didn't fight for them to make it right as much as I would now. It finally stops hard now after I replaced the butter brake pads with EBC Yellows but the SSBC rotors seem to come warped out of the box so its a bit shaky still. I'm not terribly opposed to keeping the 8.75 but if I find a cheap disc Dana60 its an obvious choice.
 
I’m curious what Dana 60 you’re thinking of that would be reasonably priced, and has cheap disc brakes on it, or available for it? Also, I’m pretty sure those 3.2x whatever gears are about as easy to find as Bigfoot riding a unicorn. I’m also with twostick, I think once you do get a 6 speed in there you’ll be rethinking those 2.76 gears. I’m pretty sure 6th would only be useable going down a mountain grade.
Travis..
 
I’m curious what Dana 60 you’re thinking of that would be reasonably priced, and has cheap disc brakes on it, or available for it? Also, I’m pretty sure those 3.2x whatever gears are about as easy to find as Bigfoot riding a unicorn. I’m also with twostick, I think once you do get a 6 speed in there you’ll be rethinking those 2.76 gears. I’m pretty sure 6th would only be useable going down a mountain grade.
Travis..
I'm mostly just keeping an eye out for the right deal. I'm not in any rush to replace the 8.75 but if I can I will. I'll probably be forced into replacing the 2.76 gears mostly just because nobody seems to make them and at 242k if I open the axle I want to put something new in. A 3.26 will still be tall enough for me anyway and not too much shorter than a viper gear. I'm sure someone will tell me that it wont be drivable without 4.11s. The viper came with a 3.09. The only thing I'm actually worried about that nobody seems to have mentioned is the tall 1st. It won't be undrinkable but parking lots might be a bit interesting. I have a felling I'll be buying a few clutches over the years.

Clearly I should have just not listed specs at all since so far the axle that I wasn't here to talk about has been getting all the attention.
 
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