65 lower control arm u bolt BROKE!!!

[65shortbox]

Here it is in the parking lot waiting for the tow...



I was exiting a parking lot to a busy street where I could not see oncoming traffic so I decided to back up and exit from another driveway. I turned my wheel all the way to the right and backed up when I heard a BANG and the wheel cut hard right. I was able to back the truck up out of the exit, got out to inspect, and I saw that my lower control arm U-Bolt had snapped! This would have been bad at highway speeds! Do you all have any explanation as to why/how this might happen? Just old parts? Maybe upgrade to the larger '73+ style LCA u-bolts? I drive this truck with my kids often and I don't want this to happen while driving. I just had the alignment done and this was my 3-4th time driving it since. Also, after I converted to disk breaks up front, I started to notice a clunk sound on occasion when I would cut the wheel hard right, left, or stop in a parking space (only occasionally). Any ideas how to make this stronger for safety sake? Thanks in advance

Here is a shot of the tire...


Control arm dangling to the floor...

[chevy_mike]

One thing I notice is I think you are missing the grease nipple on the end of the contol arm bushing (hard to tell). It is possible that the bushing seazed, tried to rotate and with the force, broke the u-bolt. I know GM went to larger size ones in '73 and you can drill out the holes and upgrade but I have never heard of an earlier one breaking if everything is working correctly (correctly greased bushings).

Glad it happened when in the lot. Nice truck that would have surely been screwed up.

[65shortbox]

Thanks for the fast reply mike! You might have a point about the grease missing on the shaft thus seizing the shaft etc. I did not consider that. I had read from others on this site that they also had the LCA u-bolt break while doing the same maneuver, backing up while cutting the wheel all the way to one side. Not sure if this exerts excessive stress on the lower control arm but sure is an interesting trend with those that have broken these bolts. Either way, I think I'll buy the Moog lower control arm shafts (K6147) for both sides and upgrade those LCA u-bolts to the beefier 73+ items. I just want to make sure this will keep everything snug and safe for years to come, with regular driving of course:-) Thanks again for your response...

Does anyone have any other suggestions on upgrading or securing these LCA's to the chassis so they don't break off?

[61_FL_Apache]

Originally Posted by chevy_mike

One thing I notice is I think you are missing the grease nipple on the end of the contol arm bushing (hard to tell). It is possible that the bushing seazed, tried to rotate and with the force, broke the u-bolt. I know GM went to larger size ones in '73 and you can drill out the holes and upgrade but I have never heard of an earlier one breaking if everything is working correctly (correctly greased bushings).

Glad it happened when in the lot. Nice truck that would have surely been screwed up.

I see the nip there..

Were you able to recover the broken U bolt. Just curoius where it broke.

[65shortbox]

Originally Posted by 61_FL_Apache

I see the nip there..

Were you able to recover the broken U bolt. Just curoius where it broke.

I saw the u-bolt still hanging there but I have not gone to remove anything yet. I will look to see where it snapped. I hope I can just re-drill the holes larger and use '73 and up replacement u-bolts. Anyone have a part number on those?

Originally Posted by GMR-PERFORMANCE

The late 70-early 80s stuff is bolt on, and I do not think on your truck you would even have to re locate shock mount.. I had to but mine is a 62. I bought all 82 chevy heavy 1/2 items and bolted them back on my 62 frame.. I did not do the cut front end off route.

Thanks GMR! I really appreciate the support! Is there a significant difference to the 70-early 80's stuff from what we have in '64-'66? I already have disk breaks, sway bar, and power steering. I'm wondering if the 70's/80's 1/2 ton front clip is a good upgrade in my case? Do the lower control arms secure to the chassis differently? Thanks again...

[losthope]

Ive heard of it happening to a couple of the local truck guys in my area! they all said to just get some new thicker later model truck a-arm u-bolts and drill out the holes and replace them should be good for a long time to come.....I havent done it yet

[LEEVON]

I probably rusted on the threads, one side has been broken for awhile causing the noise and the other cut loose. I would just replace them all with new ones, should be good for another 47years, never heard of that happening though!

[65shortbox]

Originally Posted by LEEVON

...never heard of that happening though!

That is what I thought until I read this thread:

http://67-72chevytrucks.com/vboard/s...ad.php?t=70815

[vin63]

Originally Posted by 65shortbox

That is what I thought until I read this thread:

http://67-72chevytrucks.com/vboard/s...ad.php?t=70815

Yep, it happened last month on my friend's '65 when he was backing out of shop to his driveway that hooks to the right at his home. It's a good idea to replace them, especially if they are the originals. I actually purchased new larger U-bolts for this build up, replacing the 10+ year old ones the previous owner installed. Once you install the new U-bolts, be sure the check and re-torque them periodically (once one loosens up, it puts a lot of strain on the other).

[65shortbox]

Originally Posted by vin63

Yep, it happened last month on my friend's '65 when he was backing out of shop to his driveway that hooks to the right at his home. It's a good idea to replace them, especially if they are the originals. I actually purchased new larger U-bolts for this build up, replacing the 10+ year old ones the previous owner installed. Once you install the new U-bolts, be sure the check and re-torque them periodically (once one loosens up, it puts a lot of strain on the other).

WOW! That is very similar to other's scenarios. Luckily this seems to happen when backing up in parking lots/driveways! Vin, that is a good suggestion to periodically check the torque on these from time to time. Anyone know the correct torque for the '73 and up 9/16" u-bolts? Can I use threadlock? BTW, Vin, let me know if you want to hook up some time, I'm in Whittier CA. I have been meaning to get to Ruby's here in Whittier one of these evenings to hang at the car show. Best of luck on your build...

[vin63]

Originally Posted by 65shortbox

...BTW, Vin, let me know if you want to hook up some time, I'm in Whittier CA. I have been meaning to get to Ruby's here in Whittier one of these evenings to hang at the car show. Best of luck on your build...

Thanks...I took my Super Gas car to Ruby's a couple years ago. I need to get back there one of these days.

[GMR-PERFORMANCE]

The late 70-early 80s stuff is bolt on, and I do not think on your truck you would even have to re locate shock mount.. I had to but mine is a 62. I bought all 82 chevy heavy 1/2 items and bolted them back on my 62 frame.. I did not do the cut front end off route.

[64fleetside]

Dorman/Motormite part number 13503 in HELP section-u-bolt kit, has two. You will need to redrill the X-member for the larger size.

[65shortbox]

Originally Posted by 64fleetside

Dorman/Motormite part number 13503 in HELP section-u-bolt kit, has two. You will need to redrill the X-member for the larger size.

Are these grade 5 or grade 8, or does it even matter?

Thanks...

[ol_skool_chevy]

To be honest I just installed my stepped lower control arms and as I took the old ones out i was thinking to myself " Man these things look wimpy"..But hey they lasted 50 years must be ok.
after seeing yours I might just replace them...

[65shortbox]

Originally Posted by ol_skool_chevy

To be honest I just installed my stepped lower control arms and as I took the old ones out i was thinking to myself " Man these things look wimpy"..But hey they lasted 50 years must be ok.
after seeing yours I might just replace them...

Cheap insurance for sure

[luvbowties]

Originally Posted by 65shortbox

Here it is in the parking lot waiting for the tow...



I was exiting a parking lot to a busy street where I could not see oncoming traffic so I decided to back up and exit from another driveway. I turned my wheel all the way to the right and backed up when I heard a BANG and the wheel cut hard right. I was able to back the truck up out of the exit, got out to inspect, and I saw that my lower control arm U-Bolt had snapped! This would have been bad at highway speeds! Do you all have any explanation as to why/how this might happen? Just old parts? Maybe upgrade to the larger '73+ style LCA u-bolts? I drive this truck with my kids often and I don't want this to happen while driving. I just had the alignment done and this was my 3-4th time driving it since. Also, after I converted to disk breaks up front, I started to notice a clunk sound on occasion when I would cut the wheel hard right, left, or stop in a parking space (only occasionally). Any ideas how to make this stronger for safety sake? Thanks in advance

Here is a shot of the tire...


Control arm dangling to the floor...

Thanks for the descrip of your problem, 65shortbox--def a headsup for many of us--as those orig u-bolts look too much akin to muffler clamps to me. IIRC, upgrading to some models x-members gives better design of the a-arm 'pivot-bars'(dunno proper name), the newer not requiring outdated lubricating methods, plus use of beefier u-bolts overall. Sounds as if beefier u-bolts can be used by just drilling bigger holes. If so, I'd suggest we all do a minimum of just that on all our trucks.
Since I do not recall just how we did it, I do know we: re-used original 'pivot-bars' which we disassembled, cleaned, checked for excessive play; ensured they would accept grease thru the zerks; and ended up with the beefier later-model u-clamps--I had an experienced old-pickup mechanic calling the shots & even doing some things during late PM's & early AM's when I was not around! Thanks, Gary!
Again, thx for shaing such a safety-related issue. BTW: Nice-looking pickup!

[Captainfab]

Yep, I've had it happen on my Suburban twice. The first time I was turning around in a parking lot. The second time we had just got back from a family vacation trip to Yellowstone.....I was backing into the driveway. This is why I always recommend upgrading to the larger '73+ LCA U-bolts whenever someone asks about front disc brake upgrades. When you do install the new larger diameter U-bolts, I would use the steel lock nuts, not the nylocks.

This could really be a bad situation if it happened while driving at higher speeds.

[65shortbox]

Originally Posted by luvbowties

... Again, thx for shaing such a safety-related issue. BTW: Nice-looking pickup!

No problem, I'm glad this information can go to help others. Thanks for the compliments on the truck.

Originally Posted by Captainfab

Yep, I've had it happen on my Suburban twice. The first time I was turning around in a parking lot. The second time we had just got back from a family vacation trip to Yellowstone.....I was backing into the driveway. This is why I always recommend upgrading to the larger '73+ LCA U-bolts whenever someone asks about front disc brake upgrades. When you do install the new larger diameter U-bolts, I would use the steel lock nuts, not the nylocks.

This could really be a bad situation if it happened while driving at higher speeds.

What are "steel lock nuts"? Do you mean regular nuts with lock washers? Or are there actually steel lock nuts I can get at a local bolt house? I agree, this could be bad at highway speeds for sure. Luckily, I have only seen/heard stories of this happening when backing out of parking lots or in reverse. That must put excessive strain on those u-bolts for some reason. Note to self, "don't over turn while backing up", lol....

[vin63]

Originally Posted by 65shortbox

What are "steel lock nuts"?

Stop in at King Bolt in Covina next time you're out that way...they have just about every type of fastener you'll ever need, plus other racing/high performance equipment and products.

King Bolt
4680 North Grand Avenue
Covina, CA 91724
(626) 339-8400

[65shortbox]

Originally Posted by vin63

Stop in at King Bolt in Covina next time you're out that way...they have just about every type of fastener you'll ever need, plus other racing/high performance equipment and products.

King Bolt
4680 North Grand Avenue
Covina, CA 91724
(626) 339-8400

Cool thanks! I also have a spot near home, Battles Hardware, they have a very nice selection of fasteners. I'll have to check out King Bolt though, I have heard about this place from others as well.

[dean jendro]

Originally Posted by 65shortbox

No problem, I'm glad this information can go to help others. Thanks for the compliments on the truck.



What are "steel lock nuts"? Do you mean regular nuts with lock washers? Or are there actually steel lock nuts I can get at a local bolt house? I agree, this could be bad at highway speeds for sure. Luckily, I have only seen/heard stories of this happening when backing out of parking lots or in reverse. That must put excessive strain on those u-bolts for some reason. Note to self, "don't over turn while backing up", lol....

Here's some good reading for you. Better than I could explain.
http://www.fastenerexperts.com/lock-nuts/

[65shortbox]

Originally Posted by dean jendro

Here's some good reading for you. Better than I could explain.
http://www.fastenerexperts.com/lock-nuts/

Great read, thanks for sharing!

[Captainfab]

I guess I should have expanded on the 'steel lock nuts' a little. They are just an all steel nut that has a slight taper on the top and is slightly crimped on the top. This crimp distorts the top couple of threads, which when a bolt is threaded thru, grabs the bolt tighter, essentially locking the two together. Different vendors have different names for them. Fastenal calls them 'top locks'. The supplier I buy from now calls them steel lock nuts. I feel these are a more secure type of lock nut to use, especially on critical components.

[dougf]

I am doing my suspension during my holiday leave from work. What parts would you recommend using to replace the u-bolts with? For a stock replacement would something from autozone or similar work? Just curious as to what other people out there are using. Going to do my U bolts holding my rear diff to my control arms as well, so maybe ordering online would be a cheaper option perhaps? Thanks!