1985 4Runner, automatic, 33's, 5.29 geared, 2 inch OME lift

I'm looking for insight from fellow owners of older Toyotas. I took my 4Runner in to a shop to find out what is causing a vibration and grinding sound when decelerating from 65+ mph. The shop said that my front drive shaft is likely the culprit (ujoints to be more specific) - and the fact that I shouldn't be driving over 65mph with the gearing that I have (even though this should be the correct gearing according to LCE's chart). They quoted me close to a $grand for a custom-made double-cardan driveshaft.

I asked the mechanic how the front drive shaft could be the culprit if I am driving in 2wd and he said that my front driveshaft is always spinning even in 2wd and doesn't actuate at the axles until I shift in 4wd. I disagreed but he was adamant this was the case. I didn't purchase anything beyond the diagnostic and figured if he was right, I could buy a new driveshaft elsewhere and install it myself.

Once home, I had my wife drive in 2wd and sure enough, the front drive shaft does not spin. I had her shift in 4wd and of course it spins. Back in 2wd and it doesn't spin. So, is this mechanic wrong or does it spin at higher speeds? The front drive shaft does have a lot of grease around the shaft and area so I don't doubt something is not right with that driveshaft - I'm just not sure it is contributing the the vibration/grinding sound or that new ujoints cannot be installed on a double cardan shaft (which is also what the mechanic claimed). If I do need a new driveshaft, any recommendations on brands?

Thanks,
JARED

 

If you have manual lockout hubs on the front wheels and they disengage as designed, the front driveshaft should remain motionless while the transfer case remains in 2 wheel drive.

 

Thanks Millball. That's what I figured as well as I do have manual locking hubs. You'd think the mechanic would know this. Anyways I am back to square one regarding the vibration. I'm going to check the flange nut on the rear diff just to rule that out but the driveshaft seems pretty solid without any play. I also think I will rule out the front drive shaft by running the 4Runner without it down the road in 2wd and seeing if the vibration is still there. Pretty sure there wouldn't be any harm in running it that way for a short distance. Other than that, I'm running out of ideas.


Thanks,
JARED

 

I'd avoid that shop. My newer Trucks front drive shafts spin all the time. My wife's FJ Cruiser and my RAM 2500 do. I don't like this fact. But like Millball said, if the hubs aren't locked the shaft does not turn. Unless you had the T-case engaged in 4WD. Sounds like you didn't.

Yes you can rebuild double Carden joints. I have. Sometimes it's hard to find the center joint kit though. I have 5.29 gears and 35's and have been up to 100 MPH (according to my stock speedo anyway) Faster than 65 for sure. $1000 is crazy. You can get High Angle custom shafts for less. It is around $800 for those.

When did the vibration start? After the lift? The grinding sound would concern me. Maybe drain your rear diff and check for metal in the oil or on the drain plug magnet and make sure your diff is not failing. I had a vibration ONLY on deceleration and it sounded more like the transmission area. Long story short, it ended up being me needing a double Carden rear shaft after my lift even though my drive shaft angles were within acceptable range. I tilted my diff toward the T-case and set my double Carden pinion angle and no problems since. I had to replace my spring mounts and weld them on to do so. I had more than 2" of lift though. If your rear diff looks good, maybe you can try to shim your pinion angle. Or if you don't have a double Carden rear, maybe it's time to get one. A drive shaft shop should be able to check your truck and make a recommendation. Call Tom Woods driveshafts.https://4xshaft.com/

Good luck and be sure to follow up with your fix. Dead end threads suck.

 

Thanks aztoyman. I'm definitely running in 2wd with the hubs unlocked - I can't speak for the mechanic when he tested it but that doesn't matter at this point. I don't drive the 4Runner all that much so it's kind of hard to remember but I am very sure the vibration just started out of the blue several years ago. It was after the lift but I have had that lift on it for a while and it's only 2 inches. It seems the sound became more pronounced after the re-gear which was just a few years ago. A professional shop put the diffs together and I meticulously put the shafts/axles back on (I used Redline gear oil in the diffs and I don't recalla lot of metal). It could also be a flange nut although it feels snug. I'm going to try the following:

* disconnect both drive shafts, clean and grease them (although I already do this as regular maintenance).
* drain/refill the transmission and transfer
* tighten all flange bolts (I'll look in the fsm for torque specs)
* reconnect drive shafts

If none of this makes a difference then I will give Tom Woods a call. I was looking at them anyways - seems pretty reputable. There aren't many shops where I am (and I've already been burned by this last one) so I'm probably just going to get double cardan shafts for front and rear and put them in myself.

Yep, I will provide an update to this forum. Thanks again for your advice.

JARED

 

Jared, any chance the drive shaft ever came apart at the splines and got put back together out of phase?

The vibration and especially the grinding AFTER the re-gear is concerning. Hopefully it's not the diff failing. I don't know if you ever checked out ZUK's site. It's a great reference to building your own diffs. http://gearinstalls.com/

I hope a better drive shaft is all you need.

 

That's absolutely possible - but only for the front shaft. Since lifting the 4runner, there have been times when I have worked on it and the front shaft separated due to the height difference. But i always put it back with the grease zerks lined up. Or should I have done something differently? How do I know if the splines are lined up? And thanks for the link - a lot to go through but there is some good info on that site.

 

 

Jared, I just bought BOTH drive shafts for my linked pickup build from Tom Wood's and It was just over $1K. And that's high angle Spicer Double Carden thick wall tubing shafts. Shipping included. Great customer service too. Probably closer to $400 ish for your stock rear drive shaft that will still be better than the factory Toyota shaft it came with.

Good luck sorting out your truck.

 

Can you post up a picture of the complete rear shaft installed from a couple of different angles

 

I finally got around to fixing this and am reporting back. I went with Tom Woods double cardan driveshafts both front and rear and the grinding sound at 65+ mph is gone. I also went with rear axle shims (1/4 inch) and opted to replace my ubolts. With the added shim pack, I had to extend the ebrake shoe height and went with 4Crawler's product. After a little bit of modification, they turned out pretty good. So, thanks everyone for your help. It was nice driving into town today and not hearing that dreadful sound.

JARED

 

Glad you got it fixed and THANKS for following up. It may help someone in the future.