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I guess this is mostly for the Fiero builders but I have a few questions about Chevy’s transverse trannies. So first off for perspective on my questions. I’m contemplating building a tadpole motortrike using the LSX family. The first of these questions is. Is the bottom drawing accurate to how an LS4 would mate up to the Fiero’s rear axle and would it really be as easy as just slapping a sprocket on the 4t80e or f40 and running the the chain drive or am I missing crucial information on just how these transmission actually drive the vehicles
Secondly if that drive system is viable is there a kit similar to the 4l80e to run the automatic with carbs or would a manual be my only option and the third and final question is can any other lsx besides the LS4 mate to the 4t80 or any other GM transverse? I’d prefer to use a 4.3 iron to keep costs down and the starter is already in the block.
I have not looked at a Pontiac Fiero in about 25 years, but...
The vehicle is a rear engine design with a "Trans-Axle".
There is no traditional Rear-Differential used in this vehicle.
Think of the way in-which the Engine and Trans-Axle are mounted in most Front Wheel-Drive vehicles.
The Fiero takes the same parts and simply moves them to the rear two wheels/ tires, instead of the front.
I would consider using the 4T60E/ 4T65E family of Trans-Axle instead of the 4T80E unit.
The 4T80E is massive and Over-Kill compared to the 4T60E/ 4T65E family.
Just so you know... One example of a Heavy-Duty part that is used in the 4T80E, is the Forward-Sprag.
This part/ component is so "Heavy-Duty", that is is often swapped over into both the THM400 and 4L80E transmissions...
For engine combinations that exceed 1,000 HP. The stock Sprag in the THM400/ 4L80E will not hold-up to 1,000 HP reliably,
and instead will use this Sprag from the 4T80E instead.
There really is hardly any good information for "Transverse-Transmissions/ Trans-Axles" here on LS1Tech...
I would try looking for any of the sites/ forums out there that cover Front Wheel-Drive cars, like the Pontiac Grand-Prix of the early to mid 2000s.
Good Luck and Have Fun!
Last edited by vorteciroc; Jan 27, 2021 at 09:02 PM.
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4t80e/ f40 questions 
