I was reading the new sand sports mag. I was reading the article about off road driving tips. Joe Fab and some other guy were discussing duning long travel v-8 cars. Joe was talking about preventive maintenance. One thing that he said that made me think was that you should change the bolts that attach your a-arms and trailing to your frame arms once a season. I have to admit, I have never changed mine. I always check my entire car to make sure nothing is loose but have never changed mine. Do you thing this is a good idea. I am pretty sure that when I start getting ready for the winter season I am going to change them. It could keep from breaking a bolt and screwing up your car. I would think you just need to get the weight off the wheels and change them. Am I missing anything, any tips or input would be great.

After reading that, I thought the same thing. Question for the group, anybody had one of these break? My understanding is that grade 8 bolts can cycle millions of times without fatigue.

I replace my front A-arm bolts once a season, I have seen a bolt failure on another car and it could have been bad. I replaced my rear trailing arm bolts after two seasons along with the delrin bushings. If you have the chrome plated trailing arm bolts you may find that they weld themselves inside the bushing sleeves. No more chrome bolts for me, I had to cut them out. Other than that it is not difficult and it is cheap insurance.

I am going to do it, You have the same setup as I do, where do you get the delrin bushings for the trailing arms.

I bought mine from Darren. Fodrill carries them also.

I had issues with one of mine, ended up bending and it was amother to get out.
Also saw another break last season.

I got 'F9' bolts from Don at SCU.

Got my grade 8 from Fastenal online. Way cheaper then Ace or True Value, but they do carry them.
I heard of grade 5 bolts offset 1/4" on an a arm bolt. But never seen a broken one yet.

I change my pivot bolts every season.
In the rear, while I'm changing the bolts I replace the
bushings and crush sleeves.

The tricky part is the get the rear arm lined back up with the tabs after it
is pulled away. I've found it to be easier if I disconnect the sway bar and connect a
ratchet strap from the step to the rear hub plate. With the tire on use a floor jack to
raise and lower the car to get the arm back in position, once in position use the ratchet
strap to pull the arm towards the tabs..

Replacing the bolts only is a breese.
Jack the car up enough to take most of the weight off the shock.
Pound one bolt out at a time and replace it.

IMO grade 8 is not good enough. You guys should be running F911 bolts for suspension arms. One failure will trash your car and cause some major damage. Not worth saving a few bucks over

If the bolts are tight and in double sheer, you should see no appreciable wear in a season.
If sized appropriately, you should see no fatigue.

When a bolt is loose, all bets are off. Bolts are designed as tension members. They are often used as load bearing surfaces (side load), which is no big deal as long as the appopriate size is used and IT IS TIGHT.

Bolts in single sheer experience bending stresses and fatigue much faster than those in double sheer.

Bottom line:
If your proper sized bolts are tight and in double sheer, CHECK them regularely. Replacement should not be necessary for many seasons


wild card: SAND.
If in inspection, you see that sand has gotten in and significantly damaged the diameter or the thread surface, that can have varying (bad) effects on the bolt's integrity, depending on the severity and nature of the damage.

I have broken (2) lower trailing arm bolts, (1) was a 1/2" grade 8 the other was a F911 1/2" bolt. Now maybe the f911 bolt was loose, but now switched lower heims to 5/8" bolts and will use fine threads. The depth of the threads on a coarse thread bolt go quite deep, could be my issue. Don't think I will break 5/8th's, any opinions?

Just another opinion: Make sure the bolt shoulder carries through the tab. Don't have any threads passing through the tab. Tabs and threads don't go together.

So you have to cut the end of the bolts off so it does not look like a swing set, that seems the only way to have minimal thread in the shearing area?

Sound advice right there.
The sheer strength of the thread area is SIGNIFICANTLY less than that of the shoulder. Another way to achieve this is with a fitted steel sleeve.

This is where the saying "SIZE DOES MATTER" comes into play. I am shocked that a 1/2 bolt was used in such a critical area. To give you an example I have a 3/4 socket head cap screw for the trailing arms. I run 1-1/4 heim joint on the outer arm with steel bushings to reduce it to 3/4 and a delrin bushing on the inner arm with a crush sleeve and a 3/4 bolt as well.
A f911 is equal to a grade 12 and a standard socked head cap screw is equal to a grade 11 so I chose to go with the socket head cap screw due to the fact that they are easier to find. I also made sure that all of my critical bolts are from an American manufacture. There are a lot of cheep bolts out there that are imported and are hard to tell a difference with the naked eye. Any GOOD bolt supplier can provide you with documentation of where the bolts were manufactured. Like mentioned earlier it is important to purchase a bolt that is essentially to long so the shoulder makes it through both tabs and then trim the thread length. I also included a picture of the washer reinforcements that I have welded into every tab. By using these washers it greatly increases your contact surface area allowing you to have more of the bolt shoulder in contact with the tab and not bottom the nut out on the bolt shoulder before it is truly tight. Many people have laughed at me but I do torque all of the bolts on my car as well, if you just tighten them to where you think is sufficient you could be over tightening the bolts and compromising their integrity. Just my .02

I went bigger in this area too, these are 7/8 bolts on the inner and outer bolts, i have a tig welded washer on both sides of the pivots, the bolts were long enough to have the shank pass through the tab, the end of the bolts were cut off.

Click to view attachment
Click to view attachment
This picture shos the use of welding some boss material so the full shank passes through the lower shock tabs, the bolt in the picture is not the actual bolt (as it is too short but used for mock-up)
Click to view attachment

Yep thats the correct way to do it. You want to make sure there are no threads going through the tab. Its difficult to find exactly the right length bolts, so you may need to cut down longer bolts. Thats how my car was done.

Just to clarify, I was talking front, lower a-arm bolts, and thanks for the info on cutting each bolt to length, seems time consuming but necessary in critical areas.

a aircraft supply shop will have hardware with the grip ( shank) in 1/16 incriments so you will never have threads in the wrong spot

I replacd the bushings and bolts on my trailing arms today, I took the old busings and bolts out and went to fodrills and got new bushing and f911 bolts, Denny at fodrills said I had to press the new bushigs in, I just used a long bolt with big washers, lined everything up, tighten the nut on the bolt and they went in pretty easy. there was a metal sleeve that was inside the bushings. it was very tight getting it back in, I used the same bolt set up and pressed it back in. Every thing went back together pretty easy. I used a ratchet strap to compress my springs to line everything up. gettting everything back together was pretty easy. my only concers is that the new bushings and sleeve were very tight, is this right. the old ones were looses and came out very easy. I am assuming from wear, input please

input please

The Bushing probably shouldn't turn, the brass inside is like a bearing...

Yeah, your good. They'll loosen up.
Here are mine, which I just changed.

If your changing or inspecting your bolts you have the opportunity to really inspect your heims too. I just removed my front arms for the rebuild on my car and was amazed at the wear on several of them.

I used to work for one of the largest MROP suppliers in the country, Kar Products now known as Barnes. I see some misconceptions on bolt grades and applications and thought i would offer up my .02 worth. A grade 5 bolt is the BEST bolt in any shearing application. The reason is their softer metal will bend, not break. Yes this can make them a real terror to get out but they are far far less likely to completely break or shear off causing you a wreck. Grade 8 and the Alloy bolts (f911's and grade 12/11 as your all calling them) are constructed with one thing in mind, clamping force. The much harder material in the higher grades makes them much more brittle. They don't bend well as they will snap before they bend much at all. Unless specially ordered, socket head cap screws are a grade 8, not a so called grade 11. Grade 2 bolts, carriage bolts, lag screws ect. are designed for wood applications and are the most commonly missed used bolts in the world due to their cheap cost. There is ZERO difference in strength between course thread and fine thread. Course threads are mostly used in manufacturing processes to reduce time spent on each bolt. A fine thread is better used in applications where one might be concerned of it backing out or coming loose due to movement and vibrations because it takes far more revolutions to come loose. that being said, the closer you cut your threads off to the nut, the less threads you have to retain the nut. you really should have the same thickness of your nut worth of threads showing. Take all your lock washer and throw them in the garbage. Just kidding, they are useful ONLY in applications where your using bolts in a threaded hole with no nut but loctight is even better. Otherwise use a Grade C lock nut if at all possible. They are far superior to a nylon lock nut.

Forgot to mention. If you are tired of your sockets coming off the heads of the bolts, looked for a raised head cap screw. These have a taller head giving your sockets more bite not to mention more material to hold the clamping force.

Where there is no difference in the base material strength (if the same material), the fine thread can have a greater thread contact surface area.
That can mean more clamping force, less pressure on the threads.