I'm replacing the rear toe rod assembly on my 1990 suspension. The OEM bolts holding the center of the assembly to the back of the diff case came out fairly easily and show no signs binding to the aluminum case. I haven't decided whether to reuse them or replace them with new bolts. In either case, what do you recommend I put on the steel bolts going into the aluminum case?

Here's a picture of the piece.

 

antiseize

 

I use anti seize on spark plugs for aluminum heads.
Shelf life = forever.

 

I don't understand the thought of even thinking about replacing the bolts. They're hex/washer faced and serving their intended purpose. Am I missing something here?

 

Clean the bolt threads and inspect the female threads in the holes for any sign of damage. Use a light coating of anti-sieze and torque to spec (about 55 ft-lbs).

 

Your suppose to reduce torque with anti-seize 10-20%. Since that is mostly likely a dry torque spec to begin with and not an oiled spec I'd go the high side maybe.

 

I believe that a person needs to "remember" that the female threads are in aluminum alloy and the threaded fastener is steel. I wouldn't argue the anti seize application, around here it would be Never-Seez but then it becomes a "multiple choice" as to which product.

Since the component sees no high-heat (like a cylinder head & spark plug) I don't know that "clean and dry" might be the choice, "PURPLE THREADLOCKER™ LOCTITE® maybe? A friend uses it more regular than one might think. I discussed the stuff with my Optician sometime ago and it's in my NLA frames now.

 

You have a steel bolt going into an aluminum case. Dissimilar metals will create galvanic corrosion which is why you use a anti-seize on the threads of the bolt. Failure to do so will (takes time) result in the two metals corroding to the degree that they are almost welded together. This ends up as a nightmare....having to drill out the old bolt and re-tap or the use of Heli-coil.

Save yourself future headaches and use anti-seize.

 

I understand if we're talking "off the shelf" generic bolts etc BUT the original were part # specific and likely a finish that didn't present the issue that "off the shelf" product does. Does it matter? To each their own BUT PURPLE SOUNDS like maybe the stuff.

I've never looked for any sealer on the 3 bolts mentioned on disassembly of a couple but I'll be honest - I wasn't looking. Concerned with a "galvanic" issue in my lifetime? NO

 

I've been surprised a lot of the stuff I've taken apart(steel bolts in alum) wasn't too bad on my 86, but some stuff deff gave me trouble and got a good coat of anti-seize before reassembly. Still it was in a dryer state most it's life.

Stainless bolts are other option I think for alum, idk the torque spec but most common hardware store SS bolts are low grade. Just have to make sure it's not a high torque app or find a good brand of SS bolt like ARP.

 

??? your saying that anti-seize or w/e you wanna call it doesn't reduce surface friction and give a lower reading than a dry surface would.

??? that alum isn't softer and will strip out easier if over torqued when using a friction modifier.

 

NO - I didn't mean or try to imply that it doesn't reduce and YES it is softer and being "cranked on" would/could certainly lead to failure.

 

Factory torque specs....the only figures you should use....are normally for dry, clean threads. If a lubricant is called for, it will be clearly specified. Adding a lubricant to dry, clean threads will alter the torque specs an unknown amount.
My manual calls them "axle tie bolts", and gives a torque value of 55ft/lbs. It does not specify using any lube on them, and does not recommend using new bolts.
I'd say, clean up the old bolts, install them without lubricants (including lock-tite), and torque to factory specs. Otherwise, you're trying to outguess the engineers and you'll probably be wrong.

 

 

sorry to disagree, but never put any fastener into aluminum dry; use antiseize or locktite, but use something. I helped a friend pull the steel fill plug out of the aluminum case on his Toyota truck; the galvanic corrosion had literally welded the plug into the case; even six sided sockets and a breaker bar didn't budge it, and this seems impossible, but eventually the bolt head rounded off to where even a pipe wrench couldn't grab it.

short of pulling the entire trans to drill out the plug, the only other solution was to use heat. My favorite trick of using a propane torch to heat then an ice cube to chill shock the plug resulted in nothing. Final resort was to heat the plug with a small oxy acetylene torch. Once the plug turned a dull red the galvanic bond was destroyed and the plug simply backed out without further fuss.

But that was a desperate measure...sure I work on ships and routinely use oxy acetylene to free up nuts and bolts in steel, cast iron or even bronze, but aluminum is different; overheated, the aluminum is sure to distort or even melt. And I don't even want to think what could happen with magnesium, such as ZF bellhousings.

sooo...don't take any chances, use something to breakup that potential steel / aluminum bond, it could be antiseize, loktite, or even Teflon (pipe thread) tape or paste, but use something. If you feel you have to adjust the fastener torques, well that's a judgment call, but having a fastener slightly over/under torqued will not cause near the problems that a seized fastener will.

Happy New Year everyone; one more year and my corvette will be old enough to go to the liquor store without me.

 

I'm quite sure that the OE/GM bolt is "PHOSPHATE" finished and there would be "no problems" wiping clean/dry and using as is. I mentioned I don't believe problems in my lifetime so ....

The GM part# for OE is 14050422 and it's properties can be easily searched through GOOGLE. Do you trust GOOGLE?

PURPLE or I'm kinda' likin' the thought of a very tight wrap of Teflon tape, Teflon paste is interesting OR if you've got the AS well .. certainly a choice.

 

Thanks to everyone for sharing your thoughts. I was having mixed thoughts about this question that were pretty well covered above. I found it interesting that the OEM bolts had not corroded and appeared to have some sort of coating on them. My only reason for considering new bolts was my tendency to not reuse old bolts in critical applications. I also considered using antiseize but wondered about how well the bolts would hold given the low torque needed for the aluminum case. ... Given that these bolts were not heavily stressed in their original installation, I suspect they are good for reuse, and their coating should address the dissimilar metals issue. I think I'll just clean the bolts and aluminum threads and reuse them.

 

Umm...GM put those bolts in their without anti-seize. Most steel bolts into aluminum are coated to keep the metals seperate. How long that coating lasts is up to the environment it is in and the original specifications.

Also dissimilar metals ONLY corrode in the presence of an electrolyte so salt water for instance. Put a steel bolt in aluminum and leave it in a dry place and nothing much will happen. I can only recall having issues with steel bolts in a aluminum piece only once or twice and I've done a LOT of wrenching on Northern state cars.

 

Not other than the OP over thinking a simple maintenance procedure.
Those bolts are loaded in shear so replacing them is moot.
A touch of blue loctite is all thats needed and torqued to the book.