Hello I am currently putting together a '72 Velle.
540BBC, TH400, 4.56 rear end. Considering an overdirve unit for cruising/highway and I would like to take it to the track. I really like the concept of the 30% US gear overdrive option. Anyone have any experience with them, how hard are they to put in and anyone know where to get a deal on them ?

Bowtieman,
I've never used a "US gear". But, if you're thinking of using any overdrive unit you need to be aware that if you have a higher than stock stall, non-lock-up converter, the converter will slip like crazy when the motor's turning slow in fourth gear. The best solution is an overdrive trans swap like a 700-r4, 2004r or a 4l80/85e. These trans' generally use lock-up converters so at highway speed with the engine turning slow they are very efficient.
Just thought you should know this, as I've had a few customers insist on me putting Gear Vendors OD units in and then they hated the slip at speed. But, if you really want that type of set-up, the GV overdrive unit is very popular and is very durable. I just don't know anything about the US gear unit.
mike

use a th350C with a gear vendors unit. walla overdrive and a lockup with a stronger than 700r4 and better gear spread. tom

Hello I am currently putting together a '72 Velle.
540BBC, TH400, 4.56 rear end. Considering an overdrive unit for cruising/highway and I would like to take it to the track. I really like the concept of the 30% US gear overdrive option. Anyone have any experience with them, how hard are they to put in and anyone know where to get a deal on them ?

With a 4.56 cog and 30% O/D,you will still be seeing around 3K rpm at 70mph.
What's the stall speed on your converter?

Unfortunatly it is a 3800 stall. Would a 700r4 be able to handle the torque of the 540BBC ? The 30% would put me down to a 3.11 which would be nice on the highway. Not a big fan of 700r4 in a torque monstor BBC

Unfortunatly it is a 3800 stall. Would a 700r4 be able to handle the torque of the 540BBC ? The 30% would put me down to a 3.11 which would be nice on the highway. Not a big fan of 700r4 in a torque monstor BBC

Bowtieman,
A properly built 700 will handle the 540, but if you're uncomfortable with a 700 just go to a 4l80e or 4l85e (the 4l85e is a little stronger). Either trans will easily handle the 540. The only catch with the 4l80/85e is that you must use an electronic controller with it. The electronic controller is actually a good thing as it allows easy programming of ALL transmission functions. And they also allow you to change the shift/pressure strategy on the fly by flipping a switch. The drawback is that the controller costs $700 on top of the trans.
Mike

no need for an electronic controller if you go with a fully manual valvebody with the 4l80e.no automatic shift then, but if you like banging your own gears it saves you money and is alot of fun. converters for the 4l80e can be pricey as well.

How much is a 4l80e ? and can I use the torque converter I already have ? What is the OD on a 4l80e ? any suggestion would be great.

How much is a 4l80e ? and can I use the torque converter I already have ? What is the OD on a 4l80e ? any suggestion would be great.

Bowtieman,
You can get a TCI or Hughes 4l80e from Summit for $1900 and $2300 respectively. Or you can get a GMPP 4l85e from "GM Parts Direct" for $2300.
http://store.summitracing.com/egnsearch.asp?Ntt=4l80e&N=700+115+4294861220&Ntk=KeywordSearch
http://www.gmpartsdirect.com/results.cfm?singlepart=1&partnumber=19156257

No, you cannot use a 400 converter on a 4l80/85e.
The GMPP trans comes with a 2300 RPM stall converter which you probably don't want if you're using a 3800 stall right now.
However, ATI and Hughes make nice converters for these trans' depending on your stall preference. For your stall, I would go with the Hughes 3500 lockup converter.
The 4l80/85e has an OD ratio of .75

And no, don't go with a manual valve body. It doesn't lock the converter and you only get one shift strategy/feel........manual-hard. The electronic controller allows you to program ANY desired shift strategy and feel and allows you to change it while you're driving with the flip of a switch. Well worth the money.
:beers:
Mike