6-speed for my fiero (Page 1/1) Josh86gt OCT 19, 07:30 AM I have had issues finding a decent transmission, the only ones I have found only have about 170 lb ft and I want to put a 3800 with about 20 psi of boost, does anyone know a 6-speed that would work, if not I will settle for a 5-speed olejoedad OCT 19, 08:43 AM The F40 6-speed would work, but the gearing isn't optimal, and locating axles is an issue. The F23 5-speed seems to be the current transmission of choice. Josh86gt OCT 19, 08:45 AM Ok thanks I will look into the f40 but may end up using the f23 or getrag 282 Josh86gt OCT 19, 08:58 AM quote Originally posted by olejoedad: The F40 6-speed would work, but the gearing isn't optimal, and locating axles is an issue. The F23 5-speed seems to be the current transmission of choice. I looked into the f23 a bit and I have heard they can only handle about 170 lb ft, is that a under shoot or am I going to blow this thing to bits? pmbrunelle OCT 19, 10:41 AM quote Originally posted by Josh86gt: I have had issues finding a decent transmission, the only ones I have found only have about 170 lb ft and I want to put a 3800 with about 20 psi of boost 170 lbft is with regards to the torque of the 4-cylinder application for which the transmission was tested; it can probably take more. F23 and F40 are the only « more robust »  transaxles in the Fiero world (well, also the Getrag 284…). Try an F23 or F40 with a 3800 at 20 psi, it may last for a while. Worst case if you break one, reduce the boost and it should last a lot longer before failure. You can also consider boost reduction in lower gears. Either way, F23 or F40 is a step up in robustness compared to 282. Josh86gt OCT 19, 11:00 AM quote Originally posted by pmbrunelle: 170 lbft is with regards to the torque of the 4-cylinder application for which the transmission was tested; it can probably take more. F23 and F40 are the only « more robust »  transaxles in the Fiero world (well, also the Getrag 284…). Try an F23 or F40 with a 3800 at 20 psi, it may last for a while. Worst case if you break one, reduce the boost and it should last a lot longer before failure. You can also consider boost reduction in lower gears. Either way, F23 or F40 is a step up in robustness compared to 282. Ok thanks I will probably get a f23 they seem cheap, easy to get, and I have seen one that has a 0.69 5th gear fieroguru OCT 19, 03:30 PM Either the F23 or F40 "will work", but the F40 will be 3x to 5x more expensive. However, If you want to play around with final drives to better match a high power vehicle, or have more room within the bellhousing to run a twin disk clutch for better holding power and drivability, then the F40 has options that are simply not available for the F23. Here are the available gear ratios and final drivers for the F40 - however, the final drives numerically lower than 3.545 are only available oversees (but transmissions can be imported). The F40 also as room for a 9 1/4" twin disk clutch (with a custom flywheel and some slight modifications to the pressure plate) that drives like stock. My LS4/F40/Turbo is running the 3.091 final drive and a McLeod twin disk clutch. At 4 -5 lbs of boost, the ecm is showing between 450 and 490 FWTQ from 2700 rpm to 6600 rpm (haven't dyno'd it yet or pushed the boost). I am easily over $5,500 in parts (excluding labor) from the flywheel, clutch, transmission, final drive upgrade, and axles - but I love how it drives! Josh86gt OCT 19, 03:39 PM Yeah I'll probably stick with a stock f-23 I don't have a lot of money to play around with