Thread: Vibration 40-60, Pinion Angle???

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A while back I put a Ford 9" in. All seemed well. Recently, I have developed a vibration. Now, it could have always been there and I just didnt notice, but its worse. When I ordered the rear they welded the supports on backwards! So I grinded em off and welded the leaf spring supports back on to about the way my stocker was. I probably was a little off. When its sitting flat, the 3rd member does by eye appear to be about a 1/2-1 degree down towards 8:00. If I raise the back end with air, vibration seems worse. If I lower as far as it will go, it seems to get better. I just balanced all tires at work on Saturday. Tires are perfect. Is it the Pinion Angle? I think its too low so I ordered 2 degree shims from Comp Engineering. Is the shaft out of balance? Any ideas would be appreciated...

Eliminate the possibilities one by one. First, jack up the rear and remove the wheels and tires, then run it through the gears. There is a very slight possibility it is tire/wheel related. If the vibration is still there, turn the axles by hand to see if there is any bearing problem that has arisen. If no, then I would suspect too much driveshaft angle and wait to install the wedges to see if it gets better.

The reason I question the axle bearings is because you welded the spring perches on and you didn't say that you equalized the heat all around the axle tube, so if you didn't, I suspect the tubes are all wrapped up like a pretzel and if you don't have bearing problems yet, you will eventually.

Thanks Richard, I am going to get it on stands and check it out. I did make sure not to overheat when we welded, and we did equalize that. It's got moser 31 splines and the bearings were pressed on. We did weld after the axles and bearings were installed but were careful. I am new to this ford 9" setup. When I got the rear, I was told to put RTV around the outer part of the bearing and tap them in. Now the only thing that holds them is the retainer. I have had the rt rear side pissing out gear oil since the day I installed it. I'd say about a quarter sized puddle by inner tire per 2 weeks.
Generally you would hear a bad bearing so I dont think this is the problem. When we welded I may have softened the seal a little though. Also, there are no axle seals. I thought that was strange. Is this setup correct? Do you know? Thanks.

Sounds like a bad U-joint.

9" Ford generally has axle seals installed before the axles go in. However, the bearings are sealed, and I've used the silicone method before with no oil seals. If you get a good coat of silicone, they usually don't leak. Did you weld after you installed the axles w/silicone? If so, the heat could have degraded it.

Currie sells a bearing with an o-ring around the outside diameter. It involves changing the bearings and spending som $$$, but it works. The picture doesn't show much, though.

http://www.currieenterprises.com/ces...e.aspx?id=1452

The retainer is what holds the axle in place. That's the standard setup.

welding near a bearing can arc weld the balls or rollers. this has happend to us at work even on bearings with a 12" diameter Ground placement is crutial .

Yes, we welded after axles were in. We were careful but Im thinking the silicone degraded too. So it has to be leaking around the outside of the bearing, correct? Would it leak thru the bearing? Seems crappy to buy new ones, just bought these! But if need be, I will. Actually have nothing but problems with the rear since I got it. It shoots out thru the breather like crazy.

On a more positive note, I just put the 2 deg shims in tonight. Test rode and vibration is much better. I think I need to balance shaft. I also thought u-joints, but replaced them too. Unles I overtightened them and caused some damage, but I get no clunking from d to reverse. Thnsk for all input and I will keep you posted...

I can't speak for all Ford bearings, but the ones I have are sealed. There's no way the oil is going to leak through them.

I have had those ford 9" vibrating in the past. All related to the pinion nut coming a little loose. At least something afordable to check.