4.2 5speed ?


timbecht

New Member
Joined
Nov 6, 2021
Messages
2
Location
new york
i have a 4.2 5speed yj and was thinking about doing the 4.0 to 4.6 stroker motor but i need to know if the 5 speed trans will bolt to the 4.0 block and is there any upgrades for the trans available ????
 

machoheadgames

Certified YJ Researcher
Supporting Member
Joined
May 19, 2020
Messages
950
Location
Dallas, TX
4.2 and 4.0 are almost the same block so any trans bolts up mostly the same. The cranks over the years have different diameters for pilot bearings so that is what causes the most issues with mixing trans and engines, but you can fix that by buying special bearings for each application.

The 87-89ish trans sucks, it’s a French one made by Peugeot. The 89-99 AX15 is made by Aisin Warner and miles better. It is also still made brand new in its strongest version so you can just get one of those if you want more than enough strength for a 4.6 stroker. The AX15 shifts real nice and lasts a really long time especially with the right fluid.