Overdrive for a 454?
 

My 84 K30 has a really stout built 400 trans in it but I am want to know about an overdrive. Is there an older 4l80 trans that could be swapped in with little difficulty. Were they all computer controlled? I don't want to get into having a stand alone unit. If I have to do that then I might as well look into putting in a 8.1 vortec or switch to a 24 valve cummins with an auto O/D trans.

The 454 runs just fine just want an overdrive in it. I am getting rid of all my newer trucks and going back to driving the older models and it is just kind of weird having a three speed trans. I keep waiting for it to shift. A bit more on the mpg's wouldn't hurt either if that is even possible.

Re: Overdrive for a 454?
 

4l80s are all electronically controlled.
I have heard of "built" 700s that can be used in high horsepower/torque applications but have no knowledge to pass on about them.

Google is your friend. Do a search, apparently there are manual valve body conversions you can do. But you do lose the "automatic".

Re: Overdrive for a 454?
 

I did the 4l80e swap, electronics were a piece of cake. Used a TCI controller ( about $600) I have my build posted in the forums for the swap. But I'm on my iPod and don't know how to post the link ;(
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Re: Overdrive for a 454?
 

Chuck one of those overdrive boxes on there. Can't remember what theyre called but they fit on there like a T case but do the opposite.
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Re: Overdrive for a 454?
 

Willett that's a gear vendors over drive,I would do a 700r4 beefed up some or find the 91 crew cab 4l80 np205 which can be hard or easy depending your luck.

Re: Overdrive for a 454?
 

Find an early 90's truck and swap the PCM and everything that goes with it. That'll let you step up to TBI and run the 4L80E at the same time.

Re: Overdrive for a 454?
 

Visit the Gear Vendors website to see what they say about installing a gear vendor in an automatic. You may or may not have a fuel economy benefit from installing a gear vendor. I have a Gear Vendor in my 83 C20 454 with a granny 4 speed. GV advertises a 20% improvement in fuel economy, and that was true in my case (but only went from 9 mpg to 11 mpg city.) I think highway driving would show more improvement in fuel economy, but I never drive on the highway. Mostly automatics use the GV for increased power, especially when towing. Theoretically, you double the number of gears - somewhat like an 18 wheeler.

Two downsides of the GV are price and the need to modify the driveshaft (making it shorter, to accommodate the space taken up by the GV.) I think the GV units go for about $3000-$3500, plus installation cost. You need an adapter for the type of transmission you have - you can see these adapters advertised on ebay, and they seem to go for big $$$ and sell fast. There is a shop in Las Vegas which sells rebuilt units for less.

Also, you really don't use it much in city driving. I need to be going about 35 mph to engage the GV unit or it will just lug the engine.

Re: Overdrive for a 454?
 

Tucsonjwt,

What is your rear end ratio? I always thought the GV box was mainly designed for highway use? Isn't it like adding an overdrive gear?
So you are using it to lower your drive ratio all the time above 35 mph?

Re: Overdrive for a 454?
 

I have a 4:10 rear axle ratio. Effectively, you are reducing the final drive ratio by 20% (at least that is the way I interpret it) through each gear. So, I guess my 4:10 ratio is really 3.28 when engaging the GV. Practically, I can only use the GV in 3rd and 4th gear, so I guess you could say the GV gives me a 6 speed transmission.

Coupling a granny 4 speed with a 4:10 rear axle ratio is a real mpg killer. The previous owner had a truck camper on my truck (camper special), so that is probably why he had the GV installed. I don't have a tachometer but I can sense the RPMs drop with the GV engaged.

On automatic transmissions, you can select the mph where you want the GV to engage. My truck has a 20/40 rocker switch on the dash which I think is for that purpose, but since I have a manual transmission the local GV mechanic says it is just an on/off switch in my truck.

Re: Overdrive for a 454?
 

Gear vendors have poor overdrive ratio [.82 if I remember correctly] and so aren't worth the money at all vs a 4L80E if all you want is overdrive.

Re: Overdrive for a 454?
 

4l80e = .75 od ratio
GV = .78 od ratio

The 'plus' (if there is one) is the GV unit offers the ability to use it as an under-drive in all gears so you get the HD aspect of a th400 w/the possibility of a deeper 1st/2nd like a 700r4 w/o the big ratio split they suffer from.

Re: Overdrive for a 454?
 

I've seen used gear vendors for $2500!.....I'd try the 4l80 with a tci controller or a built 700r4.....

Re: Overdrive for a 454?
 

Gear Vendors are pricey, but I think that Las Vegas shop gets about $2500 for a rebuilt one. My local GV mechanic said my old unit was worth about $1000 as a core. The used units seem to go fast on Ebay, so somebody must want them. One advantage is you get the overdrive without the electronic problems of a computer controlled transmission.

This one on ebay is a factory rebuilt unit which includes an adapter, so you would still have to shorten the driveshaft, but that's about it.

http://www.ebay.com/itm/Factory-Rebu...a5f637&vxp=mtr

Re: Overdrive for a 454?
 

You guys killing me lol

Ck performance an transmissioncenter.net

Those guys will get you big block transmissions ready for anything
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Re: Overdrive for a 454?
 

Is the 454 a stocker? If so a 700 would last ok. I have almost a hundred thousand on mine behind a 6.5 Banks turbo diesel in my 87 burb. The thing that I love about electronic transmisions though is the ability to tune them to shift exactly where you like them to. I have a 4l80e in my 72 big block twin turbo vette and its sweet!!

Re: Overdrive for a 454?
 

700r4 could be done right and cheaper then the other options. Making a 700r4 live is simple a working lock up a cooler and tow in 3rd it will live just as long as any other trans
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Re: Overdrive for a 454?
 

Keep in mind you can also have a 700R4 built to have its output shaft match a turbo 350 if you want to continue to use a NP205. It will bolt right up to the adapter. That is what I am going to do. I am not sure if a 4l80 will bolt to a NP205. Dont know if they make an adapter.

Re: Overdrive for a 454?
 

stepside man they made a 4l80 np205 but was 91 only in the crewcab of our body style,But its kinda hard to find since it was one year only tho.advance adapters does make a kit for it its 627 bucks tho.