Trailing arm hitting differential

[69MyWay]

Chris,

Just to clear it up, they only scrape on hard left turns. Also, the bump stop on the passenger side is missing. I don't know if it is possible for the bolts to scrape on full travel in stock configuration without the bump stop.

So, I'll have it looked at hopefully this weekend and keep you guys posted.

-Russ

The side yoke is the rotating assembly that comes out of each side of the diff. The half shaft axle bolts to the side yokes via the inner U-joints. The side yoke cradles two of the U-joint swivels, and the half shaft cradles the other two.

The actually side yoke should have very little side to side movement. It has a C clip on the inside that retains it in place.

That happens is the C clip may have been left off by the last mechanic in there, or it popped/wore off. The pressure from the outside has pushed the side yoke into the diff carrier. Over time, heat, and pressure, the yoke slowly grinds into the center, resulting in travel in and out. When you turn the car, now the pressure is moving the yoke into the side of the diff.

I hope I am wrong. But, it is possible that the travel stop bumper is gone or is worn down. That extra bit of travel may be pushing it to the extreme. However, if the side yokes are healthy, you should be able to run with no stop busings, and turn as hard as you want, and the yokes would never scrape the housing.

 

[Jack]

poly sources w & w/o graphite

http://www.p-s-t.com/

http://www.prothane.com/Main_Menu/main_menu.html

www.energysuspension.com

If I recall, pst has poly-graphite ... prothane swears off any graphite use in their poly ... and ES has graphite in only their black-colored poly bushings.
JACK:gap

 

[Bullitt]

I'm a bit confued. Why would the absence of the bump stop affect the endplay of the side yoke? As far as I know, we're talking about the rubber piece that mounts to the frame above the rear trailing arm assembly and only prevents the trailing arm from hitting the frame in extreme compression situations. Right?

Russ, I'll give you a call later today. Unless you don't mind a call at 3:30am. :L BTW, I live outisde of Houston on the sothwest side.

--Bullitt

 

[77-4speed]

Bullitt,

Sorry I missed your call last night, I was zainoing (is that a word?) my expedition in the garage. Didn't even hear the phone ring. The bump stop would reduce the total travel of the trailing arm, thus reducing the travel of the U-bolt threads towards the diff. I did order the bump stop and a couple of misc. stuff from zip yesterday so I'll put it on this weekend before I take it to get the yokes looked at.

If you feel like calling me again, I'll be sure to put the phone in the garage tonight.

Russ

 

[wolf_walker]

"thus reducing the travel of the U-bolt threads towards the diff"

See, that's the thing, in this design the u-bolts themselfex never move in anything other than a circle when the shaft rotates, there bolted to the flange, not the mobile portion of the joint.

 

[Bullitt]

After talking to you yesterday Russ, I gave the diagnosis some thought. I'm just wondering if the shop would be able to tell you from external appearance if the side yoke is bad. I know that if you disconnect the half-shaft from the trailing arm and pull on it, you should feel a bit of play. You wouldn't however, be able to move the yoke up/down or side to side. Does anyone agree that this method would help in diagnosing the problem or would the cover have to come off to be absolutely sure?

I'm just asking because, the diagnosis might cost more than Russ would expect to spend. Especially if they have to basically tear it down since the rear cover is bolted to the crossmember. Any ideas out there?

--Bullitt

 

[wolf_walker]

Well, if the complaint is the flange moveing inward and rubbing the bolts on the differential, I would imagine pulling the shaft off and pushing and pulling and generally harassing the crap out of the flange will tell you if it's loose. I'm sure there's a spec for use with a dial indecator, but if it's bad enough to cause bolt interferance it should be evedant. I wouldnt pay a shop more than $30 to do this, and would prefer to give them $20 just to let me borrow there lift for half an hour or so..

 

[Big Fish]

My yokes were so badly worn that one side actually ground the seal out of the differential case by wearing down the seal area. In my case the yokes worn to the splines did not offer much end play because of the way the splines were all mashed over. I had to use a die grinder to "restore" the splines just to remove them. An external inspection showed the yokes had problems however. There is shield on each yoke and one side was obviously much closer to the case than the other side. Both were too close when compared to the proper fitting yokes after rebuild. I can see about 1/8" between the outer edge of the shield to the rough casting protrusion coming out the sides of the differential. I also measured 1-1/8" between the edge of the cover plate to the inside edge of the yoke. I have the heavy duty ones (they don't use a u-bolt for the u joint), but I would think the inside edge of these would be the same as the u-bolt style which should give your u-bolt nuts plenty of clearance room. If they are hitting the side of the differential you do have a serious yoke problem which should be high on your priority list to repair.