Ok i do not have much knowledge about the 4r100 tranny i just replaced the type f fluid the previous owner put in it with merc III, i do realize i should have used merc V. The problem is the tranny slammed into second gear. I replaced the fluid and now its doing somewhat better but does hti hard at times...Should i bother replacing with merc V or just get it rebuilt? i have heard the 4r100's can be a pain.


thanks,
stickee

 

I thought the 4r100 called for regular mercon atf. I think that is regular automatic transmission fluid.

 

Merc III is still the wrong fluid. It originally speced "Mercon" which was replaced with Merc V.

 

There is no such fluid as Merc III. There has been MERCON, MERCON V, and several later MERCON fluids that won't work in your trans.

You probably have DEXRON III/MERCON fluid. That is what this trans was designed with. Later MERCON V was changed to be compatible with the 4R100 and is now the recommended fluid.

Give the new fluid some time. It takes quite a while to soak into the clutch material, so the shifts may continue to improve. If they don't then a rebuild will be the only way to fix it.

 

thank you mark ill give it a while and see how it goes.