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Toyota control arm

My mechanics tell me that on my 2005 Toyota Corolla the right lower control arm was replaced (accident before I had the car?) and the bolt is about 1/16" too small.



They said not to worry, not dangerous. Is this true?

Sounds like someone subsituted whatever was lying around rather than make sure the proper bolt was used.

Dangerous? Probably not, but IMHO 1/16" is a pretty big amount and I would not consider this acceptable. This could allow the control arm bushing to wallow around on the bolt and wear it out even faster plus there is the possibility of the control arm squirming around on the undersized bolt. This can affect handling and tire wear.

My feeling is if your mechanics noticed it they should have fixed it. This is a cheap, 3 minute fix.

Addendum. I’m going to back up a minute here. It could be dangerous depending on what TYPE of bolt was used. Automotive fasteners should always be Grade 5 or Grade 8 at least. If this bolt was one of those Grade 2 bolts from Home Depot that are used to hold fences together then it could be a problem and should be changed instantly.

This came to me because I thought of a vehicle in which someone changed the engine/transmission a couple of years ago and used Grade 2 bolts on all of the engine mounts. Not only did they use inferior bolts but they did not even tighten the Grade 2 nuts that were screwed onto them. The complaint was “engine vibration” go figure.

Thank you for replying! The mechanics (whom I have always trusted totally) told me that it would be $150 labor (including the tiny cost for the bolt) to replace the bolt.
Does this seem accurate? I have always trusted these mechanics, but I’ve only been with their shop for a year. They have excellent recommendations and charged me nothing to examine the brakes, find the bad bolt, etc.
You say it’s a “cheap, 3 minute fix.” Is this for a mechanic at a shop or a do-it-yourselfer, which I am not…

How did you know the OP was refering to the bolt diameter not lenght?

I was thinking it was a little short and would not be a problem, I did not even consider that someone would use a bolt whose diameter was 1/16 smaller than required, not something I would do even in a pinch.

Wouldn’t this bolt be a “special bolt” and not a off the shelf item?

Maybe I need to see a picture

I’m assuming diameter here because it’s hard for me to see how someone could pick out 1/16" difference in length.

While I’ve never had the opportunity to change a control arm bolt on a late Corolla the only ones I’ve ever seen that could be a bit of a chore were the ones on some of the old domestic cars; say 40 year old Chevys with rusted together upper control arm bolts.
I don’t see a late Corolla as being much of a problem at all.

Those bolts are definitely not fence post bolts but I’ve done repairs with over the counter bolts with no worries at all but I’ve always used Grade 8s. Grade 2 or 3 would never be considered and even 5s are a toss-up.

Just curious. How or why did this incorrect bolt diagnosis come about?

I went in because my brakes were making squeaking and sort of creaking noises, stopping okay, but annoying me. They ended up telling me that the brakes were okay, the rotors had “slight ridges, .915 left/.911 right. Too thin to machine: minimum is .906.”

In seeking to diagnose the noise problem, they had the car up on the hoist and informed me about the bolt, printed out a diagram for me so I would understand where the bolt was and that it was possible it could make a noise. On the diagram they have written “SPO” with an arrow pointing to the bolt, but I don’t know what that means.

They told me it was not dangerous, it was $150 to fix, and I shouldn’t worry about it. Also, I could have the brakes done in the future; they were okay right now.

They charged me nothing for over an hour of diagnostic work.

I hope all this information is helpful. I am wondering what to do about this bolt! My brakes have begun creaking again when I’m applying them, so I’m ready to have them fixed, but I really don’t want to pay for this bolt to be replaced! Should I ask them if it’s a Grade 8? Would that help be reassuring that it’s not dangerous?

SPO = SPecial Order, maybe, How did they know about this bolt being undersize? I thought maybe the had the car on the alignment rack and saw a incorrect angle, I guess not.

Ask if you wanted the exact bolt from Toyota would it have to be special ordered, I would want the exact bolt that Toyota called for,after all you have the time to get the right part and installation is pretty expensive.

I agree that it’s pretty simple to just buy the bolt that is made for this particular application. They should not be too expensive anyway.
The only reason I’m pointing out using an aftermarket bolt is that an aftermarket Grade 8 bolt is just as hard as what the factory put in there to begin with.

One way of determining the grade of the bolt is to look at the face of the bolt head. It will have a series of lines on it.
A grade 2 or 3 bolt (skip these) will have no markings or 2 short lines on it.
A grade 5 bolt (acceptable) will have 3 short lines.
A grade 8 bolt (preferred) will have 6 short lines.

No matter the grade, if the bolt has a shank that is narrower by a sixteenth as compared to what’s supposed to be in there I would definitely change it PDQ. It won’t break but will affect handling/tire wear.
You might consider getting the Toyota dealer to look at this. The price may not be as bad as you think.

As to your brake noise, some squeal or squeak can be normal with used brake pads and rotors and while irritating, is not a safety issue.
The creaking noise you mention is probably not related to the brakes. That is often the sign of a groaning sway bar bushing. Those rubber bushings harden and dry with a little age and will cause this problem. This is also not a safety issue but more one of irritation than anything else. Some silicone based grease is the best thing to use on them and it usually shuts them up for a long time. Hope that helps.

Both of you have been so helpful! I’d expect nothing less from the Car Talk Community, of course… Thanks so much.