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Strut Rod to LCA Bolts Failure?

Posted By: cjskotni

Strut Rod to LCA Bolts Failure? - 03/30/13 01:32 PM

Guys,

I was driving my '73 Charger last week and noticed what sounded like a bolt hitting the underside of the car. I got it home and inspected the engine compartment and didn't see anything amiss. I figured I must have hit something on the road.

I took it out last night and noticed that while it did drive straight, when braking it pulled hard to the left! Basically a lane change when I hit the brakes!

I figured stuck caliper but I peeked around under the car and and see that the two attachment bolts that secure the strut rod to the LCA on the driver's side are simply...gone. Other side is fine

Any idea what would cause this? I have a hard time believing they were loose and both happen to fall out at roughly the same time. I am wondering if they were sheared off somehow.

The suspension is stock excpet for polygrphite bushings and a bigger sway bar. Could this be putting stress on those bolts and maybe cause them to fail? Do I just need to go buy a set of grade 8 bolts and call it a day?

Hope I am not overthinking this but I wan to know why this happened. Thanks!
Posted By: TMCCuda

Re: Strut Rod to LCA Bolts Failure? - 03/30/13 01:39 PM

Not sure for a '73 but the strut rods on my '70 e-body go from the k frame to the LCA and are threaded on both ends. The forward nut is secured with a roll pin. If the roll pin was left off after repair/ upgrades then I suppose it could come loose?

Are you sure it isn't the sway bar attaching point?
Posted By: bigblock340power

Re: Strut Rod to LCA Bolts Failure? - 03/30/13 01:44 PM

I am wondering if they were sheared off somehow.




Are all the threads still there? If so I don't see it (the bolts) shearing off. You have any pics?
Posted By: mcmopars

Re: Strut Rod to LCA Bolts Failure? - 03/30/13 02:45 PM

Quote:

Not sure for a '73 but the strut rods on my '70 e-body go from the k frame to the LCA and are threaded on both ends. The forward nut is secured with a roll pin. If the roll pin was left off after repair/ upgrades then I suppose it could come loose?

Are you sure it isn't the sway bar attaching point?




i thought all strut rods go through the lca and are threaded.at least the a bodies are
Posted By: twodoorpost

Re: Strut Rod to LCA Bolts Failure? - 03/30/13 03:17 PM

For those unfamiliar with the set up in question, here's a pic of the lower control arm. As far as the problem, the bolts could have loosened up at different times, but the problem only became obvious after the second one fell out.

Attached picture 7646893-Bbody1973-74withswaybar02.jpg
Posted By: cjskotni

Re: Strut Rod to LCA Bolts Failure? - 03/30/13 03:54 PM

Quote:

For those unfamiliar with the set up in question, her's a pic of the lower control arm. As far as the problem, the bolts could have loosened up at different times, but the problem only became obvious after the second one fell out.



Thanks for the picure! Yes this is exactly what I am talking about. I find it hard to believe these loosened up on their own....I torqued all these down years ago myself.

I had the car in a few months ago for an alignment and to set camber, caster, etc. Would these have been loosened up to do those adjustments?

I just hate to fix this and have it happen again. Maybe I am just worrying too much about this.

Second question now:

How to get the strut rod back where I can align the holes to push the bolts through? I am guessing I will have to take the sway bar off its mounts on that side to give the strut rod more wiggle room so I can pry it back into place.
Posted By: moparmikethree

Re: Strut Rod to LCA Bolts Failure? - 03/30/13 04:21 PM

someone was tampering with your car, maybe an ex.
time to sell the car.

Just put in 2 new good quality nuts and bolts and youll be fine.
torque them to proper setting
Posted By: TMCCuda

Re: Strut Rod to LCA Bolts Failure? - 03/30/13 06:06 PM

Learn something new every day...
Posted By: challengermike

Re: Strut Rod to LCA Bolts Failure? - 03/30/13 06:30 PM

Make sure you look good at the upper control arm mounting tabs that they didn't crack where they are welded to the body. My car I have now had bad strut rod bushings and it broke off the tab that the upper arm bolts into because of the back and forward motion of the lower control arm. The person that owned it before me crashed at the track due to it busting off. This is an a body but im sure it still applys to a b body.
Posted By: fourgearsavoy

Re: Strut Rod to LCA Bolts Failure? - 03/30/13 06:55 PM

Chris I would look into the way the alignment shop adjusted your caster.Maybe in an act of desperation he may have tried to get more caster by loosening the bolts and pulling the arm forward and he might have forgotten to tighten them afterward
Gus

Attached picture 7647163-savoyburnout.jpg
Posted By: NachoRT74

Re: Strut Rod to LCA Bolts Failure? - 03/30/13 08:49 PM

Quote:

Learn something new every day...



yeap... 73 and lates B bodies changes ALL the front end system... that's one of the differences.
Posted By: cjskotni

Re: Strut Rod to LCA Bolts Failure? - 03/31/13 12:01 AM

Thanks for the help guys! I went ahead and replaced all four (both sides) with new stainless hardware and used the blue locktight on them so hopefully no issues in the future!

I torqued them to 50 ft-lbs and did some massaging of the sway bar and its mounts, rebulubed the bushings, etc.

I had a slight front end clunk on some turns before and now that's gone as well!! I tok it out to an empty lot and did some driver's ed type stuff and she is silent! Oh yeah, and doesn't change lanes when I hit the brakes!

Thanks for the help and reassurance, guys! And yes, for those who don't know, 73 was a major turning point for the B-body suspension....totally different from the 72-before setups....makes getting good aftermarket parts hard for us later 3rd gen guys as we share the same suspension as the later B-bodies Cordobas, etc through 78 or so.

Posted By: moparx

Re: Strut Rod to LCA Bolts Failure? - 03/31/13 02:00 PM

glad you got the problem fixed, but if i were you, i would dump those stainless fasteners asap ! stainless is not ment for critical load bearing situations as it has way less of the tensil strength of a grade 5 or 8 bolt. this is especially true of hardware store bolts which are usually inported. the main cause of this is the fact stainless is different from normal steel in that it doesn't tolerate as much stretching prior to failure. stainless may be good in the fact it does not rust, but i have not found a source that has the tensil strength i would trust for suspension applications. stainless may be good for show cars and trailer queens, but not, in my opinion, for the street or track.
Posted By: fourgearsavoy

Re: Strut Rod to LCA Bolts Failure? - 03/31/13 03:38 PM

Quote:

glad you got the problem fixed, but if i were you, i would dump those stainless fasteners asap ! stainless is not ment for critical load bearing situations as it has way less of the tensil strength of a grade 5 or 8 bolt. this is especially true of hardware store bolts which are usually inported. the main cause of this is the fact stainless is different from normal steel in that it doesn't tolerate as much stretching prior to failure. stainless may be good in the fact it does not rust, but i have not found a source that has the tensil strength i would trust for suspension applications. stainless may be good for show cars and trailer queens, but not, in my opinion, for the street or track.



There are some graded stainless bolts but only available through certain aircraft suppliers. I only use good quality American grade 8 bolts for ANY suspension part
Gus

Attached picture 7648247-savoyburnout.jpg
Posted By: jcc

Re: Strut Rod to LCA Bolts Failure? - 03/31/13 03:45 PM

I agree dump the ss asap
Posted By: cjskotni

Re: Strut Rod to LCA Bolts Failure? - 03/31/13 07:10 PM

Quote:

I agree dump the ss asap



Noted! I will swap these out for grade 8 in a few weeks when I can stomach getting back under the car.

Thanks for the help!

BTW found one of the missing bolts at the end of my driveway this morning. I am guessing when I was backing out a few days ago, this fell out and was the last straw.
Posted By: torkrules

Re: Strut Rod to LCA Bolts Failure? - 04/01/13 08:55 PM

Quote:

glad you got the problem fixed, but if i were you, i would dump those stainless fasteners asap ! stainless is not ment for critical load bearing situations as it has way less of the tensil strength of a grade 5 or 8 bolt. this is especially true of hardware store bolts which are usually inported. the main cause of this is the fact stainless is different from normal steel in that it doesn't tolerate as much stretching prior to failure. stainless may be good in the fact it does not rust, but i have not found a source that has the tensil strength i would trust for suspension applications. stainless may be good for show cars and trailer queens, but not, in my opinion, for the street or track.




I agree. I would go grade 8 or better. I even used lock nuts on my 74 Charger and checked them before bringing the car out in spring.
Posted By: WayneM

Re: Strut Rod to LCA Bolts Failure? - 04/02/13 12:18 AM

Older Dodge "D" series (2WD) LCA's are similar. I had one and had the same problem.
At the time I had access to awesome Caterpillar hardware (beyond Gr8) and I put em in. Never looked back...
Posted By: dogdays

Re: Strut Rod to LCA Bolts Failure? - 04/02/13 01:08 AM

Stainless varies in grade, some stainless steel is very strong. But the hardware store type bolts are probably not as strong as Grade 8, which is what I would use personally. It's all the bolt you'll need.

Mopar engineers didn't waste money on ultra-strong bolts, if they needed more strength they just used a bigger one! Grade 8 (six marks on the head) is as much as they used, to my knowledge. Well, except perhaps rod bolts.

R.

PS: Foreign bolts with 8.8 on the head are NOT grade 8 bolts and should be left in the bin.
Posted By: Sunroofcuda

Re: Strut Rod to LCA Bolts Failure? - 04/02/13 04:23 AM

I agree - ditch the stainless bolts - not strong enough. You cannot harden stainless. Find some made in USA grade 8 - don't mess around with suspension hardware - use the very best! DO NOT use any made in China hardware! Their metallurgy is not good & their ratings cannot be trusted.
Posted By: dogdays

Re: Strut Rod to LCA Bolts Failure? - 04/02/13 05:12 PM

"you cannot harden stainless" tell that to the custom knifemakers who use surgical grade stainless steel in their creations.

The problem with THIS WHOLE SUBJECT is this:
Saying "stainless steel" is like saying "rice" or saying "bread". All three examples have many, many, varieties and the only thing in common is the name.

It drives me crazy to hear some of the faulty explanations, none of which are true and even if they WERE true it'd only be for ONE VARIETY of stainless steel.

To add to the problem most of the members of this board have little true understanding of metallurgy or "strength of materials". I put that last one in quotes because it is generally a second- or third-year college course for civil and mechanical engineers. It takes time to learn what is really happening, or at least a credible explanation of what is happening.

So for now let's leave it at, "You'd be better off using US-made grade 8 bolts, 6 marks on the bolthead, and using the stainless steel bolts somewhere else."

R. Now I feel better.
Posted By: TC@HP2

Re: Strut Rod to LCA Bolts Failure? - 04/02/13 05:28 PM

Quote:


PS: Foreign bolts with 8.8 on the head are NOT grade 8 bolts and should be left in the bin.



X2.

Many foreign bolt manufactuers use metric grading scales which have a different set of formulas for determining strength and a foreign graded 8.8 is not an equivilent to a SAE grade 8. A foreign grade 12.9 may be bit closer to an SAE grade 8.

Agreed on SST types as well. 303, 304, 313, 316, 18-8, there are lots of different stainless grades.
Posted By: cjskotni

Re: Strut Rod to LCA Bolts Failure? - 04/02/13 07:05 PM

I have already purchased the same bolts/nuts in Grade 8 and will swap them out soon.

These were made in Taiwan (just like every other bolt in the store) but they have the 6 marks on them and were marketed as "SAE Grade 8".

Good luck trying to buy bolts not made overseas. Even when I order bolts from McMaster Carr, they are almost always from China/Japan/Taiwan sometimes Germany for the SS rivets. Unless all these hardware stores are just flat out doing false advertising, I think I will be fine with these overseas bolts. I really hope so because I have used these Grade 8's all over my suspension in various places.

I know how people here feel about all things made in China but that seems to be the way of the world.
Posted By: 6PakBee

Re: Strut Rod to LCA Bolts Failure? - 04/03/13 12:51 AM

Quote:

"you cannot harden stainless" tell that to the custom knifemakers who use surgical grade stainless steel in their creations......



I agree that "stainless steel" is a pretty general term. But the common 300 series stainless steels can't be hardened by heat treatment like a high carbon steel. I think that's what the comment actually meant.
Posted By: moparx

Re: Strut Rod to LCA Bolts Failure? - 04/03/13 02:56 AM

Quote:

Quote:

"you cannot harden stainless" tell that to the custom knifemakers who use surgical grade stainless steel in their creations......



I agree that "stainless steel" is a pretty general term. But the common 300 series stainless steels can't be hardened by heat treatment like a high carbon steel. I think that's what the comment actually meant.


and as i stated in the begining, i have not been able to find "good quality" ss bolts i would TRUST to use in suspension applications for street or track use. the most COMMON ss fasteners available today are hardware store imports which are ABSOLUTELY NOT SUITABLE for suspension use. even the "specialty" nuts & bolts places that sell "showcar" stainless fasteners are suspect to me because i feel the asking price for their products seem to indicate only moderate quality. high quality ss fasteners are EXPENSIVE ! oh, don't forget the anti-seize or the threads WILL gall...... and not to stir the pot, but i'm just wondering if "surgical grade" stainless would be suitable for automotive use. maybe apples to cumquats comparison ?

metalurgy and strength of materials have been with me for over 40 years. i understand most don't have the experiance, so i try to simplify explanations.
Posted By: screamindriver

Re: Strut Rod to LCA Bolts Failure? - 04/03/13 03:25 AM

Quote:

Make sure you look good at the upper control arm mounting tabs that they didn't crack where they are welded to the body. My car I have now had bad strut rod bushings and it broke off the tab that the upper arm bolts into because of the back and forward motion of the lower control arm. The person that owned it before me crashed at the track due to it busting off. This is an a body but im sure it still applys to a b body.



I've seen the mounting tabs have issues with the worn strut bushings also...But in 73 the B body went to a different UCA mounting system attached to the K frame...



Something to look for that has'nt been addressed :
The strut rod is a stout piece in 73 compared to the LCA mounting points...Make sure the loose/lost bolts did'nt oblong the holes in the LCA...You cant have any slop in those holes or the hardware won't have the ability to keep the strut in place...There's quite a bit of shock/stress all working against the fasteners..
Posted By: cjskotni

Re: Strut Rod to LCA Bolts Failure? - 04/04/13 02:56 PM

Quote:

Quote:

Make sure you look good at the upper control arm mounting tabs that they didn't crack where they are welded to the body. My car I have now had bad strut rod bushings and it broke off the tab that the upper arm bolts into because of the back and forward motion of the lower control arm. The person that owned it before me crashed at the track due to it busting off. This is an a body but im sure it still applys to a b body.



I've seen the mounting tabs have issues with the worn strut bushings also...But in 73 the B body went to a different UCA mounting system attached to the K frame...



Something to look for that has'nt been addressed :
The strut rod is a stout piece in 73 compared to the LCA mounting points...Make sure the loose/lost bolts did'nt oblong the holes in the LCA...You cant have any slop in those holes or the hardware won't have the ability to keep the strut in place...There's quite a bit of shock/stress all working against the fasteners..



I did check for the holes getting ovaled out and they look good! I am going to try and swap the bolts out today or tomorrow. I used 50 ft-lbs...is this a good spec? What would you guys recommend. This is using blue thread locker.
Posted By: mod5v

Re: Strut Rod to LCA Bolts Failure? - 04/04/13 06:35 PM

Are they 7/16" bolts? thats what they looked like to me when i glanced at the 73 i am parting out. the torque chart said 63ftlb max for a 7/16x14 grade 8 so I would torque them to 55 with the locktite and call it a day.
Posted By: cjskotni

Re: Strut Rod to LCA Bolts Failure? - 04/04/13 08:02 PM

they are 1/2" bolts. I torqued them to 55 ft lbs with locktight.
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