Over drive
Thread Starter
W30
Joined: Feb 2016
Posts: 529
From: Cape Cod Ma
Over drive
I have an origanal w30 transmission in the car.
I have 323 years as its air conditioning
I'd like to swap to 390 rear and gear vendors overdrive.
is this best?. I'd think...
323 x 390 ratio would need a new carrier?. Ware to buy?
btw..dont use a/c but rather keep car origanal _ / need better highway speed, and around town performance.
thank you
I have 323 years as its air conditioning
I'd like to swap to 390 rear and gear vendors overdrive.
is this best?. I'd think...
323 x 390 ratio would need a new carrier?. Ware to buy?
btw..dont use a/c but rather keep car origanal _ / need better highway speed, and around town performance.
thank you
Out of Line, Everytime😉
Joined: Dec 2006
Posts: 10,083
From: Melville, Saskatchewan
What year? The new 3.42 or 3.90 Richmond gears are designed to work with the factory Type O 3.08-3.23 carrier. The other option is a 2004R, which needs a lot of upgrades along with at least a new yoke or a 4L80E, needs a controller, bell housing adapter but will survive a stock W30 with just some line pressure mods. Either the gear vendor or 4L80E have a .75 od gear but the 4L80E lowers 250 to 300 rpm more due to the lock up converter. Both need the driveshaft shortened and cost similar, comparing a complete overhaul 4L80E.
Last edited by olds 307 and 403; Mar 18, 2019 at 08:20 PM.
Out of Line, Everytime😉
Joined: Dec 2006
Posts: 10,083
From: Melville, Saskatchewan
If it is 68 and up, the 4L80/90E will fit, very tight though. As said, a wash in price. You will end up with lower cruising rpm with the .75 vs .78 OD gear and the 250 or so the lock up converter gains. The gear splitting might be nice with the gear vendors, your call.
CH3NO2 LEARN IT BURN IT
Joined: Jul 2010
Posts: 5,628
From: Land of Taxes
IMO...Keep the TH400. Tried tested n bulletproof.
Go with GV. Save the original driveshaft and other pieces. Have Dennys make you a new aluminum shaft. Less reciprocation weight and you get to split 3 forward gears. Run a TCI stall converter (2400)and use the TCI synthetic trans fluid(on a fresh rebuild of course). This set up will take repeated beatings. There are some mods required with whatever direction you go in. Nothing that can't be reversed.
There are vendors offering some pretty good 200s nowadays.
Take apart a TH400 and TH2004R and compare. You will see the lack of beef in the 200. I'm from the school of bigger is better. A 200s guts are much smaller. I could never get one to outlast a TH350 or 400 with big block torque, neither could my gear head racer and firemen buddies. They grenade with surprising destruction. It was a poor design when introduced. It took till recently to engineer enough upgrades to make it survive. Yes, you can build one to withstand the torque but you said you wanted to keep the 400.
Go with GV. Save the original driveshaft and other pieces. Have Dennys make you a new aluminum shaft. Less reciprocation weight and you get to split 3 forward gears. Run a TCI stall converter (2400)and use the TCI synthetic trans fluid(on a fresh rebuild of course). This set up will take repeated beatings. There are some mods required with whatever direction you go in. Nothing that can't be reversed.
There are vendors offering some pretty good 200s nowadays.
Take apart a TH400 and TH2004R and compare. You will see the lack of beef in the 200. I'm from the school of bigger is better. A 200s guts are much smaller. I could never get one to outlast a TH350 or 400 with big block torque, neither could my gear head racer and firemen buddies. They grenade with surprising destruction. It was a poor design when introduced. It took till recently to engineer enough upgrades to make it survive. Yes, you can build one to withstand the torque but you said you wanted to keep the 400.
Registered User
Joined: Jan 2010
Posts: 6,095
From: central Indiana
I’ll say it again, if you have to have overdrive, the gear vendor or 4L80 is the only way to go. You could bolt all the fancy upgraded parts made into a 200R4 or 700, it’s still weaker than a basic stock 4L80. And all those upgraded parts are probably more expensive than buying the transmission controller and other parts to make a 4L80 work in a non computer controlled application. If you use a early non center-lubed core, the cooler lines are in the same location as the old school transmissions. The 96 and up (I think) center lube 4L80 have one cooler line fitting moved to the middle of the case, and require a special cooler fitting, and custom hose, plus a little floorboard work.
I have a gear vendor in my 69, it is a tight fit and requires some floorboard massage to get it in there. No cutting of the floor, just some minor denting and “moving” the metal. It’s not that hard to make it fit.
I have a gear vendor in my 69, it is a tight fit and requires some floorboard massage to get it in there. No cutting of the floor, just some minor denting and “moving” the metal. It’s not that hard to make it fit.
Registered User
Joined: Jun 2018
Posts: 309
I've been pondering this myself as i wait for my motor to take the truth detector test (dyno). I'm at 7000 ft and will give up about 33% of my HP, but I'd like to roast tires when I want and drive 1-2 hours on the freeway when I want to hit some car shows. My '68 came with 3.23s but I have a rebuilt 4.10 rear axle ready as well. Overdrive is really the only way for me to accomplish my goals. The older OD trannys clearly don't survive long behind a BBO and the newer stuff is pricey and more of a restomod/pro-touring type upgrade. For guys like me that are trying to keep it relatively original the choice seems fairly obvious. Use the 3.90s/4.10s and bolt a GV onto the back of the TH400 and call it a day.
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