Changing out 4-speed to 5-speed (Page 1/1)
altownsend JUL 15, 08:18 PM
1986 Fiero GT 4-speed Manual

I have a 1986 Fiero weak V-6 engine with a 4-speed manual transmission. I am changing this out to a 5-speed and looking for a fresh/strong 3800 to swap out.

My question/request for information: I have the opportunity to purchase a 2009 Pontiac G5 2.2L 5-speed manual transmission at a reasonable price. I am likely to purchase a used 3800 and ask for members here whom have done the engine swap before to share with me what I will need to make the combination work properly. Please be specific since I will follow those instructions to guide my work.

Please comment on what year engines will work with the 2009 G5 5-speed transmission. Will I need to change out the ECM if the 3800 engine was supporting an automatic transmission or try to get the 3800 ECM? Will there be engine mounting and fit issues? Will there be engine/transmission fit issues? What clutch set-up should I use. Will I need a different shifter set-up to accommodate the 5-speed? Anything else will I need to know in preparation to have a successful swap?


pontiacfierokid1985 JUL 21, 10:09 AM
Personally I would stick with the 4 speed with your 3800sc coming from a guy that has a 3800sc 4 speed done in his 86 gt. It’s honestly not bad to drive at 80 I’m right at 2700-2800 rpm. Yea the 2200-2400 rpm would be nice but hey I’m still seeing 180-200 miles from a full tank with it thats me actually getting into it and driving it like it should be your 3800 build can come out cheaper then you expect if you keep the 4 speed and the trans will hold up all day long as long as you ain’t neutral dropping it at 3000-5000 rpm.
Matthew_Fiero JUL 21, 04:12 PM
The 4sod Muncie is known as the strongest transmissions that came with the Fiero. I second that I'd love to see lower RPM at highway speeds but is it worth the extra work to get an extra gear or two?

My recent thoughts have been to slowly accumulate either F23 or F40 parts to prepare for the inevitable day it goes. It's difficult to find Muncie parts or transmissions now.

My suggestion: build your 3800 swap with the 4spd. If you end up going F23 later on you're farther ahead with the 3800 installed. If you go F40 be prepared to spend a lot of time, money or both.

Archie's F40 kit is recommended if you have the money and if he he still providing that service.

Raydar JUL 22, 09:39 AM

Originally posted by altownsend:

...I have the opportunity to purchase a 2009 Pontiac G5 2.2L 5-speed manual transmission at a reasonable price.

That 2.2 appears to be the Ecotec engine, according to an article I found. If that's the case, the tranny will not bolt to the 3800.
If you want an F23, you will need the one that came with the 2.2 pushrod motor. Or at least the bellhousing case half from it.