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4R70W 0r 6R80

73azbronco

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Didn't see it mentioned right, or I missed it, these trannies are not rated in HP, they are rated in torque, so a 6r80 will handle 800ft/lbs of torque. 4r70=700ft/lbs. etc.

Glad to see the 6r80 coming to fruition for EB's, it was to much of a gamble when I dropped dime on an NV4500.
 

nvrstuk

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I have been following 6r80 swaps for several years now. I have seen a lot of dyno slips with stock 6r trannys handling rwhp & torque consistently surpassing 800/800. These are rear wheel #'s. Very impressive.

There are a couple basic clutch upgrades and other mod's that allow these to handle well over 1,000 rwhp and 1,000 ft lbs. Not something many of us have to worry about. :)
 

Broncobowsher

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That was a concern of mine but if I had one, everyone here would understand what I would do first thing... WEIGH every pc of rotating mass of their unit and compare it to an OE flywheel, plate and disc. :) I do it with almost every part.
...

Only trouble with that is weight alone isn't a solid measurement of inertia. The old flatheads have an inertia ring on the outside diameter of the flywheel. Inertia is mass at a radius from the centerline. That inertia ring puts a lot of mass as far from the centerline as possible. Gave the heavy flywheel with less material.

If you take a 10 foot stick of 2 inch tubing. It is easy to spin and stop the tubing with that 1" radius. A quick flick of the wrist and you can spin and stop the tube half a turn in a second. Very little inertia. But take that same mass, spin it lengthwise (swap end for end). Takes a lot more effort to get it spinning, and stopped, and several more seconds to do so. You are spinning the mass on a 5 foot radius and not a 1 inch radius. Same mass. Radius changes.
 

nvrstuk

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Exactly. Weight isn't just weight. But when referencing tires, flywheels and specifically in this case a large dia, albiet alum spacer ring-- it isn't just weight. Starting and stopping that mass takes torque like you said.

Start slinging 42" tire wheel combo's that approach 175# and it's not just getting them moving but trying to slow them down becomes an issue also.

Just like the F150 vrs F250 debate for towing. It's not just climbing that hill when towing your Bronco at 60mph that is important... can you stop that 8,000 #'s that's following ya with a lighter truck with less braking capacity? Not enough people pay attention to those details... :)
 

Broncobowsher

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I have been following 6r80 swaps for several years now. I have seen a lot of dyno slips with stock 6r trannys handling rwhp & torque consistently surpassing 800/800. These are rear wheel #'s. Very impressive.

There are a couple basic clutch upgrades and other mod's that allow these to handle well over 1,000 rwhp and 1,000 ft lbs. Not something many of us have to worry about. :)

Not ft-lbs. N-M (Newton Meters). That is what the whole auto industry run on. And that is not engine input, that is torque convertor input. After the multiplication in the convertor. Can't just multiply the numbers together, you have to take the engine torque curve and run each point of the curve against each point of the convertor multiplication curve as it comes up to speed factoring the K-factor slippage during the sweep. Still does not define a black and white line either. Sustained loads vs. spike loads. What ever conservatism they want to put on it as well.

But 80 is higher than 70, so the 6R80 has more capacity than the 4R70.
 

markw

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Congratulations distended! Following your experience cause I've got a 408 as well. I'm a year off from starting my build and I want to do it right and do it once. Nvrstuck you have a huge knowledge and experience base and your input is greatly appreciated.


Sent from my iPhone using Tapatalk Pro
 

nvrstuk

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Yes, the 800/800 quote was only for dyno slips - not insinuating that the "80" in 6r80 meant "800".

Just trying to let the guy asking what they are rated for to let him know how much actual hp and torque they can consistently handle with actual dyno slips- not just tossing #'s around that is so common on line and around campfires :)
 

SavageBurro

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Aug 12, 2013
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I know a couple guys w 6r80. Awesome trans. Great ratios. I just couldn't afford it so i did 4r70w and atlas.
Donor trans 100
Local rebuild 1300
Controller 800
Eng Adapter 0
Atlas 2500
Tcase adapter 0
Dshaft mods 300
Sell c4 and d20 - 1000

Total ~4000

Drivetrain is a bit on long side w stock 4r70w adapter and output w speedo...but works.

Need to find time to get few kinks ironed out but so far its great. 2.8 1st is good for normal driving but wouldn't hurt to have lower for crawling. Crawling is actually good but i think 6r80 1st would be spectacular...and would allow a bit higher acle gears too. Od is awesome
 

nvrstuk

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$500 and it's legit and not burned up is a really good deal. Prices have increased on them like unleaded at the pump in one year!! :(

My local yards want more now than on the same year trans with 1/2 the miles from a little over a year ago! Guess they got popular. :( The car guys are sucking them up fast. Early classic cars and late model Mustangs.
 
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hossbronco

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I ran across this Speed Gems adapter a few months back and plan on using it. By my calculations, I estimate the 13 lb. torque converter adapter will cost me about 5 hp at 2,000 rpm and 25 hp at 5,000 rpm. I spend most of my time in low rpms, so not a huge concern there. Not ideal, but worth it for a clean install.

So I'll be running a 427W Stroker, 6R80, and Atlas 3.0 with this adapter.
 
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Madgyver

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$500 and it's legit and not burned up is a really good deal. Prices have increased on them like unleaded at the pump in one year!! :(

My local yards want more now than on the same year trans with 1/2 the miles from a little over a year ago! Guess they got popular. :( The car guys are sucking them up fast. Early classic cars and late model Mustangs.
shipping kills it. i got to find one local..
 

hossbronco

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I paid $500 for mine on eBay, and it included shipping from New York to Utah.
 

nvrstuk

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6r weighs 213#. Check 5 bags at airport at 50#'s each. Get two free bags and pay $50 each for the other three bags full of 6r80 "parts" and for $150 your trans is in Hawaii and ready for assembly! lol
 
OP
OP
distended

distended

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6r weighs 213#. Check 5 bags at airport at 50#'s each. Get two free bags and pay $50 each for the other three bags full of 6r80 "parts" and for $150 your trans is in Hawaii and ready for assembly! lol

:cool: Very creative.

I'm just posting this for anyone who was following.

I got my 6R80 from Car Part Planet. It came out of a 2014 V8 F-150 4X4. I had to pay an added $75 to have it shipped to my house. Shipping to a commercial address is free. It sounds like people found them for quite a bit less than what I paid but this is what I could find when I was looking. I'm still going to replace the Lead Frame. I've watched some videos on the YouTube and it looks pretty straight forward.

I decided to go with the Speed Gems Adapter, they offer a package deal. If you buy the US Shift Quick Six Stand Alone controller at the same time from them, you save $125.

For the transmission cooler I bought one from Power by the Hour.

I bought a rebuilt Transfer Case from Toms Bronco Parts. I had a T.C. but it was a basket case. I think it was pretty complete comparing it to images of parts breakdowns, I know for sure I didn't have the main drive gear.

I bought some Motor Mounts, the Transmission to T.C. adapter and the 6R80 Transmission Cross Member from Wild Horses.

Cool story on the Wild Horses order. When I placed the order, the address was right, but I didn't catch that my computer had put in the incorrect zip code, DAMN YOU AUTOFILL!!! The day before the order was supposed to be deliver, a Sunday BTW, I caught my mistake. I was able to make the correction on the shippers website but being that it was a Sunday I wanted to double check with the shipper on Monday morning. In the morning after having to deal with the shippers stupid computer phone system I spoke with a gentleman who made sure the corrections were made, didn't seem like the online changes I made Sunday were in place but maybe I remember incorrectly. Anywho, I was told that if the order wasn't delivered on Tuesday/Wednesday at the latest (since the drive time between zip codes was two hours or less) go ahead and call back. Come Friday I still hadn't received my order, so I called back. After having my inquiry “escalated and investigated” I heard back on Saturday. Saturday! Apparently, my order had been lost. I was informed to contact the Vendor and inform them of this. I kind of thought this was weird but, okay.
Come Monday, I call Wild Horses and tell them what I was informed. I get put on hold for like three minutes, about 20 times shorter than I had to spend lost in the shippers phone system, I was told they were able to confirm that the shipper had lost my order somewhere in one of their warehouses. They looked up my order and resent me everything, no more questions asked other than if anything from the original order shows up to let them know. The crossmember and the adapter actually showed up. I called and they gave me UPS return shipping numbers. I retaped the boxes because they were pretty banged up andÂ…Bada-bing! Bada-boom! Bob was my uncle! Done and done!

Saying all this because after receiving some great advice from all who were gracious enough to comment but especially BRONCOBOWSHER and from NVRSTUK, I felt like I was on the right path.

I'm going to start a build thread, not because I'm so impressive that there'll be so much original content but because I want to just document it for when I sell it for $100K+. Really it goes back to advice from a member here.
 

nvrstuk

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SCORE!! :)

You are on your way. Absolutely do a build thread. I recommend them to everybody (might have been me??) as it's a great resource to have for the fine details you might have forgotten that you did 5, 10, 15+ yrs ago!

My .02, put the build thread in tech section since it's a technical build thread right?? :)

Glad the parts are coming in!
 
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