SBC trans (Page 1/1)
Darren's 87 coupe JUN 16, 12:16 PM
What's the strongest possible trans you can mount to a SBC 383?
darkhorizon JUN 16, 12:41 PM
F23.

The biggest transmission issue with fieros is usually the clutch ive found. The v8 archie swap clutch is usually a little bigger than the fiero sized clutch so you might not have many issues up to 500whp, but beyond that you'll want to look into something better.
Darren's 87 coupe JUN 16, 02:32 PM
Is there an automatic that would be stronger or is the manual the strongest?

Thanks
fieroguru JUN 16, 08:02 PM
4T80 would be the strongest auto if you plan to keep it transverse. It will need a transmission controller or your SBC will need to run an LS based ecm. Not sure if you have an Archie or Zumalt kit, but for the autos I prefer the Zumalt for a more compact package and flywheel/starter solution. Just be forewarned, going auto with the 4T80 will require cutting the stock starter pad off the engine block. So it will be ruined for any non-fiero application. No one sells a SBC/4T80 kit, so be prepared to make some parts.

In the manual transmission group, I would go F40 6 speed and not look back. GM rates it higher than the F23 and it has some great options for final drive swaps if you actually plan on driving it. I reworked a SBC/F23 swap after I finished my LS4/F40 swap. I would drive the LS4/F40 car to work and back, then drive the SBC/F23 in the evening tuning it as well as doing shake down runs. Both are V8 cars with 400+ fwhp, and the driving experience between the two transmissions was night and day in favor of the F40 (it is even better with the 3.09 final drive swap!).

The F40 is definitely more expensive than the F23, but it is a great transmission that you can still get with zero miles. With the 3.09 final drive swap, it is the only manual transmission that you can reach 45 mph in 1st, 85 in 2nd and cruise 80 mph @ 2021 rpm. I logged 55K miles with mine alongside a 382 whp LS4 w/o issue.
Darren's 87 coupe JUN 16, 08:05 PM
Thank you so much for the input. That was the manual I was planning on if going manual.
sourmash JUN 16, 08:19 PM
From out of left field....has anyone considered the Cayman/Boxster S manual? Not the normal Boxster.

[This message has been edited by sourmash (edited 06-18-2020).]

Will JUN 19, 09:42 AM
If going longitudinal, I'd go for an Audi oB3 gearbox, as it puts the axle between the engine and clutch, several inches "forward" relative to the engine than in most transaxle configurations... which leaves more room for the engine in the Fiero engine bay.