what is wrong with overdrive transmissions?
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From: Jersey boy
what is wrong with overdrive transmissions? why do people say its so har to bulletproof an overdrive transmission? the general concensus is that a th350 is the way to go with high horsepwer because you cant beef up a 4L60 enough. so why is this? you dont race in overdrive so that shouldnt even be a factor. does the overdrive weaken all the other gears or something? im so confused 
Re: what is wrong with overdrive transmissions? The 4L60 was not designed for real high power. TH 400s are easy to build strong and the manual shift eliminates the computer which tries to balance line pressure and drivability.
Re: what is wrong with overdrive transmissions? It's not that you can't make a beefy OD transmission.
It's that OD transmissions are made for the specific
purpose of fuel economy, with cheapness being a close
second, and every excess penny and pound has been
engineered out.
That means plenty of marginal internals to replace.
Or, you pick up an OD tranny that was "value engineered"
for a heavier-duty application and hammer the "value
engineered" sheet metal until it is made to fit.
It's that OD transmissions are made for the specific
purpose of fuel economy, with cheapness being a close
second, and every excess penny and pound has been
engineered out.
That means plenty of marginal internals to replace.
Or, you pick up an OD tranny that was "value engineered"
for a heavier-duty application and hammer the "value
engineered" sheet metal until it is made to fit.
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From: Jersey boy
Re: what is wrong with overdrive transmissions? so basically if your willing to shell out some cash an overdrive tranny can be made just as strong as a non OD tranny. you would just have to replace more parts to get it there?
Re: what is wrong with overdrive transmissions? Well, presuming you can get the parts and there's
enough space in the case... but the case is a
shrink fit to the cheapo guts, more or less.
The aftermarket transmission vendors have the
weak points pretty much figured out and it only
takes money to replace the most common weak links.
Which leaves you with the next-weakest, etc., etc.
You can get 4L60E units that are rated above what
most of us will ever put out, and warranted long
enough that you can find out whether it's true
(at least in the short term destruct sense).
You can beef up the stock unit considerably
but it's still a lightweight compared to the
TH-400 or its overdrive offspring, the 4L80E.
You compromise weight and volume to get that
durability @ input torque.
enough space in the case... but the case is a
shrink fit to the cheapo guts, more or less.
The aftermarket transmission vendors have the
weak points pretty much figured out and it only
takes money to replace the most common weak links.
Which leaves you with the next-weakest, etc., etc.
You can get 4L60E units that are rated above what
most of us will ever put out, and warranted long
enough that you can find out whether it's true
(at least in the short term destruct sense).
You can beef up the stock unit considerably
but it's still a lightweight compared to the
TH-400 or its overdrive offspring, the 4L80E.
You compromise weight and volume to get that
durability @ input torque.
Re: what is wrong with overdrive transmissions? I think, it's because the 400's and such have been around for something close to over 30years.It's had alot of time to be refined, or, it may have been good from the get-go. If I had a single purpose car, that didn't need overdrive, that would be another question, then I would use the old 400's. Would I put a 30year old designed transmission in my car, for the street? No way! There's a place that's making some better parts to strengthen the 4L60E. Here's their link.
www.transmisioncenter.net/4L60E.htm
www.transmisioncenter.net/4L60E.htm
Thread Starter
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Joined: Mar 2003
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From: Jersey boy
Re: what is wrong with overdrive transmissions? ok thanks for all the info guys. this is my daily driver so i really want to keep the overdrive. anyone in the market for a stock 4l60E?
