Well I have all my parts for the trailing arm rebuild and was wandering what was specs for rear bearing end play?I've heard anywhere from .001 to .008. What would be optimum?

 

For general use, aim for between 0.001-0.003" and you'll be good to go. IMHO 0.008", tho "acceptable", is rather too tolerant. FWIW, mine are at 0.001", the max end play recommended in the Chevy Power book for RR prep.


TSW

 

I set all of mine to 0015-002. I just did a set that changed on me in final install, I had 004. I broke them down and threw them out. At 003 you'll feel endplay. Since you're doing the job- do it right and keep it at 0015-002"
BTW, the set that I tossed were a set of vendor bearings I tried. I normally buy them from a direct bearing supplier, cost more but I've never had to throw any out once I set them up. I should have known better.

 

Gary, not arguing with your expertise, as you've done vastly more of these than have I, but is it your opinion that 0.0010" is just too tight? ...and for our benefit might you elaborate? I'm always open to learning from guys, such as yourself, who know what they're talking about.

 

I have mine set at .001 to .003 also. I do that to limit changes in camber and toe in cornering. The car doesn't see much regular driving. I assume the tighter the end play the better chance of premature wear?

 

Part of the varience in setting these up is the load placed on them during endplay check. I use the setup tool with a kurled handle so I can apply uniform force to them. Some use a turned down spindle, others a tool with just a hex nut end. I'm not sure how well those will work, I have never used them. Keep in mind that the load can deform the cage are time so you want to be careful with leverage. The cheaper bearings often have this happen during setup.So I set the endplay at the setup tool, knowing full well if I placed a wheel on the spindle I could force them more, that is not the point.

I set them ot 0015 with only spindle oil, when torquing to 100 ft/lbs they will not bind at that point- again using a quality bearing such as the USA Timkens.
If the bearings bind in the setup tool then they're usually under 001" and I wouldn't set them there.

I just did an arm last night and set it at 0015 with ground to size shims, spacer parallel ground, flange parallel ground. I do not use Mobil 1 grease anymore on rear bearings. When I finished torquing them, they were smooth, no lateral play, endplay about 001" but keep in mind this is with grease and seals installed.

Some of the crap I've seen out there are bearings set so tight that you have to force them to spin and others so loose you can feel the spindle move in more then several thousands.

On that job I did, I mentioned elsewhere, that I first used a set of common vendor type bearings,they cost less, and also didn't hold the endplay. I set that at 002 and they came in at 004. I broke them down and tossed them out at 004" set up my suppliers USA Timkens at 0015 and they stayed dead on at 0015 even when I went a little over 100 ft/lb to line up the cotter pin. I use pins that are almost a press fit- no play in them at all.

Hope I anwsered your question?

 

We set all of our trailing arms to .001 to .0015 end play. Some racers want .0000 so we do what the customers want for their aplications. In days of old some of the racers even had the outside bearing journal ground undersize for a slip fit! The manual calls for going up to .008 but that is way too loose. We have never had a return for a bad bearing. We only use Timken bearings!

 

There a few people on here who set them up at 0.000. But.. that doesn't allow any margin for expansion when everything heats up. They claim that 0.000 works just fine. I can't contest or verify that. However... these are guys that I believe do the work themselves and can yank their spindles apart anytime they see fit. For someone who is farming the work out, and for the vendor they farm the work out to, an endplay of .001 to .002 is a little safer. I also shoot for .0015 because at .001 they can stack up on assembly to 0.000 sometimes. So... .001 is fine as a final assembled figure. I have found out, as Gary has, that the assembly procedure plays a role in setting these up. To test for endplay, the mechanic has to force the fixture from one extreme to the other to read the endplay on the dial gage. The amount of force applied at this pont can affect the dial age reading. If you press really hard, you can squeeze an extra .0005 to .001 out of the dial gage. If you don't press hard enough, you can be loose by .0005 to .001. It's supposed to be a science, but there is just a little bit of art involved.

If you're a vendor, or somebody who does these professionally, it's important to be consistant. I'm happy with anywhere between .001 and .002, although I tend to stay away from .002 as much as possible because after a little break-in, the number can sneak up to .0025 or even .003, and .003 is unacceptable to me... you can feel a significant amount of camber movement at .003.