swapping out automatic transmission to a 4t60 (Page 1/1)
richard in nc SEP 15, 07:28 PM
i have a 1987 fiero 2.5 automatic.its actually quite peppy around town.but id like to also use it on the interstates where the speed averages 80.im lucky?to have a 1989 4t60 from a 1989 riviera[actually reatta].id like to swap it in.i know it will bolt to the 2.5.i know that it doesn't need a computer to work.i believe the fiero tv cable will work plus a vaccum source for the modulator.what i need to know is....does anyone make a 'kit' for this?if not what mounts?is it possible to do this without removing the engine?what axles do i use?i realize the speedometer will have to be adapted too.
82-T/A [At Work] SEP 19, 09:17 AM

quote
Originally posted by richard in nc:

i have a 1987 fiero 2.5 automatic.its actually quite peppy around town.but id like to also use it on the interstates where the speed averages 80.im lucky?to have a 1989 4t60 from a 1989 riviera[actually reatta].id like to swap it in.i know it will bolt to the 2.5.i know that it doesn't need a computer to work.i believe the fiero tv cable will work plus a vaccum source for the modulator.what i need to know is....does anyone make a 'kit' for this?if not what mounts?is it possible to do this without removing the engine?what axles do i use?i realize the speedometer will have to be adapted too.




Hey Richard... this is a link to a page on my personal website (Tech section). I stole everything from the Fiero Addiction website, which no longer exists: https://www.pontiacperforma...es/4_Speed_Swap.html

It lists step by step instructions for swapping in a 4T60 or 4T40 automatic. It also lists the part numbers for the axles that you need to buy, etc. There is some notching that will need to be done to the frame to make it fit, but if you can weld, it's a really easy job. If you don't know how to weld, you can pick up a flux-core welder from Harbor Freight that doesn't require gas for like $200 bucks, and it shouldn't be too hard. EDIT: Looks like you only need to modify (weld) your cradle if you have an 88. If you have an 84-87, you're good to go... you literally just need to drill a hole, and that's it!

Here's also a page that I stole from somewhere that lists all the gear ratios, etc., by year... so that you can determine what you have and what you need so your speedometer can be adjusted properly: https://www.pontiacperforma...icles/4T60_Info.html

[This message has been edited by 82-T/A [At Work] (edited 09-19-2023).]

fierosound SEP 19, 10:28 AM
Karl Hamilton's original article about the 4-speed swap on SpaceCoastFiero
https://web.archive.org/web...s.com/tech/440-4T60/

------------------
My World of Wheels Winners (Click on links below)

3.4L Supercharged 87 GT and Super Duty 4 Indy #163

[This message has been edited by fierosound (edited 09-19-2023).]

ArthurPeale SEP 19, 01:04 PM
with this replacement transmission, how much slower does the engine run at normal highway speeds ?
richard in nc SEP 19, 07:57 PM

quote
Originally posted by 82-T/A [At Work]:

this is exactly what i was looking for.thanks a lot.

Hey Richard... this is a link to a page on my personal website (Tech section). I stole everything from the Fiero Addiction website, which no longer exists: https://www.pontiacperforma...es/4_Speed_Swap.html

It lists step by step instructions for swapping in a 4T60 or 4T40 automatic. It also lists the part numbers for the axles that you need to buy, etc. There is some notching that will need to be done to the frame to make it fit, but if you can weld, it's a really easy job. If you don't know how to weld, you can pick up a flux-core welder from Harbor Freight that doesn't require gas for like $200 bucks, and it shouldn't be too hard. EDIT: Looks like you only need to modify (weld) your cradle if you have an 88. If you have an 84-87, you're good to go... you literally just need to drill a hole, and that's it!

Here's also a page that I stole from somewhere that lists all the gear ratios, etc., by year... so that you can determine what you have and what you need so your speedometer can be adjusted properly: https://www.pontiacperforma...icles/4T60_Info.html
Cajun SEP 25, 04:44 PM
I did that swap into my 86 GT years ago! You will enjoy the difference in engine speeds at highway speeds. For my 2.8 at 70 mph with the stock tranny my engine was screaming around 4000 rpms. With the 4T40 the engine speed dropped to about 1900 rpms. Big difference and the bonus was added gas miles per gallon.

Enjoy...
82-T/A [At Work] SEP 26, 07:42 AM

quote
Originally posted by Cajun:

I did that swap into my 86 GT years ago! You will enjoy the difference in engine speeds at highway speeds. For my 2.8 at 70 mph with the stock tranny my engine was screaming around 4000 rpms. With the 4T40 the engine speed dropped to about 1900 rpms. Big difference and the bonus was added gas miles per gallon.

Enjoy...




Hey Cajun, just curious... did you notice any performance difference? Perhaps the engine stayed in it's power-band more regularly? Or did you see a decrease in performance because of the extra shift at WOT?


Thanks!