bbrideau

So about a year ago i bought a 91 4runner 3V-FML for the wife. The front diff had gone on it when the PO had it and was replaced with a non add diff and same with the tubes, the hubs were never changed out so it was locked in all the time. The truck WAS ADD before all that swap out. I have manual hubs I'm going to put on the front to rectify that issue.

Onto the issue, wife picked me up form work we drove down the highway, very very bad vibration all of a sudden from the truck, I know its not u joints because i just did the rear u joints and the front D-shaft checked out fine when i pulled it off to do the clutch a few months ago. Checked out all the front end stuff and the drivers side CV is solid no play in it, at least nothing to be worried about. Passenger side however has some issues, the side going to the tire is solid no play there, the side going into the Diff is sloppy, probably 3/4 to 1" of up and down play. Before i go pulling the CV, would this be the CV or is it the Diff?

Sorry for the long winded post but i figured the more info the better. Thanks in advance guys

highonpottery

iTrader: (1)

i would guess diff. exactly where are you seeing the play? on the actual CV shaft or from the stub shaft/mounting plate that the CV attaches to on the diff? if it's the first, then your issue is the CV axle. if the play is from the stub shaft coming out of the diff, then your issue is diff related. there are several things that I can think of failing - oil seal and needle bearings (or brass bushing) collapsing, allowing shaft to move. axle shaft breaking, allowing movement. c-clip inside diff unseating and allowing shaft to move. carrier bearings inside diff failure allowing movement. carrier inside diff failure (you'd hear grinding though). most likely my guess is related to that stub shaft.

i'm guessing your still running stock gears - i would just go find a used diff and swap it in. replacement diff will almost always come with the axle shafts inside. pretty sure the short shaft is the same between ADD/nonADD diffs, but the long-side is different (depending on which you get) if you need to swap them over. might not be a bad idea to replace the seals on the ends of the tubes at the same time since you don't know how old they are. i wouldn't worry too much about mileage on the diff if it's a non-ADD version since it's unlikely it's seen a lot of miles (whereas an ADD diff has been rotating for same miles as the rig).

not a very complicated task to swap out, just a difficult one since the unit is so heavy with awkwardly uneven weight distribution. definitely install your manual hubs when you do this - this too is a very simple install. i would also suggest that when you have the diff out, to press out the splined studs that bolt up the CVs and grind off the splines for significantly easier CV removal in the future.

good luck!

bbrideau

her truck is completely stock its a mall crawler, all i know is cv has major play and i can hear it when shes driving gonna have to crawl under and see where it moves maybe post a video, will have to take a look again i know the whole CV moves. I have no issue swapping diffs if that's the problem, it's finding one that's the problem. small mountain town and no local wreckers. Thanks for the tip on the studs tho, will have to do that for sure

highonpottery

iTrader: (1)

in the meantime i suppose you could install the manual hubs and leave them unlocked - should keep the front diff from moving as nothing will be connected at that point until you put in 4wd and/or lock hubs.

bbrideau

Yea, that's what i might have to do seeing as the wife has a 14 hour round trip drive coming up in less than a week. From what i have read its pretty simple unbolt the add hubs and bolt on the manual ones. couldn't find any write ups on it, mind you i didn't search to hard either just glossed over a few things.

Thanks for the help!