Blu ... driveshaft?

[nipper]

I am going to be away till tuesday, but i figured i would let this one sit and simmer for a while

 

Blu 1997 OBW 245,000 miles, 45,000 on rebuilt engine. One frt driveshaft replaced aabout 40,000 miles ago one rebuilt 30,000 miles ago. Recent work, two new front ball joints (dealer installed) right fron inner tie rod (last week). Left front will be replaced because, well its old when i come back. Wheels are in balance and have been rotated.

 

After the last wheeling trip Blu devloped this odd vibration. I though it was mud in the wheels. It never went away. We found a torn inner tie rod boot, and replaced the boot and the end 1 week ago. When the car was at the dealer 2 weeks ago, aside from bad ball joints they found nothing at all wrong in the front end. Since the car was goofy in a crosswind I had them replace the ball joints. I figured if there was money to be made the dealer would find it. He also said the front axles are fine.

 

Vibration is still there:

 

Vibration comes and goes. It feels like it is origniating in the front end of the car (mid point forward). At times you can go all the way to 80 and smooth as silk.

 

Below 40 it doesnt exist.

 

It builds like a sine wave, At the peak you can feel it in the brake pedal, steering wheel, and the car lightly shakes.

 

I noticed something yesterday, the AHA moment. Going around a curve at 60 mph it started then held untill another curve, then built up. At another curve it dropped off.

 

Have I ever told anyone I hate the way sooby front CV joints are mounted .

 

Something was out of balance or out of synch. Only one thing can get out of synch really, wheels or the driveshaft. Since the tires were rotataed and the vibraiton never changed i ruled them out.

 

It finally stopped raining today. I got the car up on ramps. As far as I can tell the rear universal joint is good (but there is too much slop in the rear diff, but I will live with that) Can someone with a high mileage sooby tell me how many degrees of freeplay they have, so I know whether to ignore it or not (most likely will ignore it). It is devloping that 70's mopar thunk . Carrier bearing and universal seems ok. Front Universal is hard to tell but there is some side to side in X but not Y. It is super super minor but it is enough for me to think thats the reason for the vibration. There is no comparable play anywhere else in the driveshaft.

 

My guess is that when it gets into 3rd or 4th harmonics when the driveshaft roates at a different speed from the frt driveshaft. The car shakes untill it rotates at a different speed (a curve) and then gets back in synch. If I get a straight stretch after things vibrate, I have a tough drive untill it gets back to where it is happy.

 

this is the only thing I can think of. The last time I had a bad uni was in a 87 GL, and that one almost fell out of the car it was so bad. This one is just very subtle on physical inspection. It almost seems like there is play in the tailshaft itself, thats how subtle it is.

 

So Blu is going to sit out this road trip, well he is going to Hershey PA then from there we will take my partners CRV (ick) to chicago.

 

I think I have it pinned down, but my self confidence is shot lately, as life has been getting really hard with really no real moral supports or confidants around. Everything just seems so bleak, but thats not something i want to burden anyone with.

 

So is my logic valid?

 

Thanks.

[erik litchy]

i would check to make sure any wheel weights came off from the offroad?

and replace the u joint any play is BAD.

[nipper]

i would check to make sure any wheel weights came off from the offroad?

and replace the u joint any play is BAD.

 

Wheels are fine. On Blu you replace the driveshaft. Luckily i know someone with 2o of them in his garage. It's just so odd that I can tell without dial indicators (its that small) but they were stolen along with some of my tools also.

[CNY_Dave]

If more than one wheel is *slightly* out of balance, and the wheels are indexed such that they cancel each other out, you get a smooth ride.

 

You go around a turn, and change the indexing (phasing) such that 2 or more are now shaking in the same direction at the same time, and you feel the shaking.

 

I had what you describe when I had a lot of crud on the wheel-hub interface, the wheels were never quite parallel to the hub, or centered quite right. same thing, just adding out-of-round to the out-of-balance, except that no amount of balancing would fix it.

 

 

Dave

[lostinthe202]

One of those auto-lore things I learned as a wee teen is that if you can get play in a u-joint in any direction by hand, then it is worn out.

 

Don't know if that's strictly true, but they are cheap enough so I always abide by theory.

 

I've had a couple of worn out u-joints over the years, but they were worn when I got the vehicles and like your GL, they were so bad it was amazing the shaft didn't drop.

 

Will-

[idosubaru]

Subaru ujoints will not at first show play when they start to go bad. They will be lumpy, which really only shows itself by removing the shaft and checking it. I have also seen seized ujoints which exhibit no play at all, but are seized, meaning they won't move at all by hand.

 

If you have play, it sounds like the shaft is in bad shape. They can finally break and cause some nasty wreckage. There are pictures on here of transmissions with cracked casings from such failures.

[erik litchy]

Wheels are fine. On Blu you replace the driveshaft. Luckily i know someone with 2o of them in his garage. It's just so odd that I can tell without dial indicators (its that small) but they were stolen along with some of my tools also.

 

i think the joints them selves can be replaced its getting the old ones out thats a bugger

[ron917]

These guys sell replacements for "non-replaceable" U-joints: http://www.rockforddriveline.com/replacem.htm

 

I haven't needed to use them yet, but I saved the bookmark because I know I'll need one someday.

[shortskoolbus]

i think used driveshafts are like 100 bucks on ebay.

[ericem]

New ones are $100 to

[subaru360]

If it changed on a curve that is a real good sign a front wheel bearing is going. When you make slight turns it loads and unloads the front bearings.

[Yo'J]

I was at 220,000 when it was the steering rack giving me slop. Same or similar symptoms. I replaced everything, or planned to, till it was finally it, unmistakably. (Then I was hit day after christmas, finalizing the deal.) It was only then I began to worry under 40mph. It was almost like a bubbled tire but only at fifty. Its all cheap .....but the rack, so do the rest too. You will be happy.

Edited May 21, 2009 by Yo'J

[newg]

I had similar vibration...could not figure it out.

Even brought it to the dealer to check...nothing.

I drove it with the vibration for 18 months. It finally

went away when I had new tires put on....imagine that....