Frame Bolts August 25, 2021, 11:42:26 am Not sure if I’m using the correct term terminology but does anyone know if there is a torque rating for these frame bolts? They are the bolts that connect the rear bumper to the frame. Looks like the are Grade 5. Factory install, I’m guessing.
Re: Frame Bolts Reply #1 – August 25, 2021, 12:26:16 pm Hi Greg,If I am correct, those are 1/2X13 grade 5 bolts. Torque should be about 75ft/lb.Locktite would be a good idea if you loosen them.Harold
Re: Frame Bolts Reply #2 – August 25, 2021, 01:04:38 pm Thanks, Harold! Not going to take them off but just cinched them up to proper specs. They were a little loose so I’ll add this to my annual checklist. Made a little note so I remember how much to torque them to! Now I need to inspect all the welds.
Re: Frame Bolts Reply #3 – August 25, 2021, 01:15:22 pm On our 2003 LD, years ago we had the bumper bolts loosen and lost one bolt. The grade 5 bolts and hardware were replaced with grade 8 bolts and nyloc nuts( lock nuts), with the new torque being 120 ft/lbs. The hitch bolts were upgraded too after finding the hitch plate slightly moving when properly torque.Both of these upgrades are recommended if you tow. The bolt torque should be checked annually or more often if towing often.Rear bumper mounting repair | FlickrHitch receiver upgrade | FlickrLarry 4 Likes
Re: Frame Bolts Reply #4 – August 25, 2021, 02:06:38 pm An upgrade is a good idea, Larry; think I’ll take your advice. I removed one of the bolts and will check Home Depot later this week. Just took a look at the welding at the hitch and bumper areas and didn’t notice any cracking or deformity. I must say the Lazy Daze welders did a good job. As a former Navy NDT inspector, I’ve seen worse welds. Then again, they probably weren’t hanging upside down in the bilges while welding!
Re: Frame Bolts Reply #5 – August 25, 2021, 03:02:25 pm Larry,Are the Grade 8 bolts readily available at Home Depot?For the reinforcement plate shown in your link - would I have to special order from a local machine shop?
Re: Frame Bolts Reply #6 – August 25, 2021, 03:30:41 pm Quote from: socalendos - August 25, 2021, 03:02:25 pmAre the Grade 8 bolts readily available at Home Depot?For the reinforcement plate shown in your link - would I have to special order from a local machine shop?Depending on the local stock, Home Depot or Lowes should have the bolts along with heavy washers and nyloc lock nuts.Nyloc nut - WikipediaThe sandwiching plates were cut and drilled from stock on hand, bought possibly from HD or Lowes. Our 2003's bumper was not an example of good workmanship, the wide adjustment slots were cut by an unsteady hand with a cutting torch, a milling machine or CNC plasma torch would have been a more appropriate means of producing the slots.Larry
Re: Frame Bolts Reply #7 – August 25, 2021, 04:09:09 pm Larry, the slots on mine looked pretty clean. Looks like LD improved their workmanship at some point.
Re: Frame Bolts Reply #8 – August 25, 2021, 04:39:54 pm Quote from: HiLola - August 25, 2021, 04:09:09 pmLarry, the slots on mine looked pretty clean. Looks like LD improved their workmanship at some point.The slots on our LD were so wide that the washers caved in, allowing the nuts to loosen. Good that they sorted the problem out, if the slots are properly sized, there isn't a need for the sandwiching plates but there is no downside to using them either.Larry
Re: Frame Bolts Reply #9 – August 25, 2021, 08:51:31 pm Grade 8 is not necessarily better than grade 5. The tensile strength rating is better but the grade 8 bolt is more brittle. The grade 5 bolt is more ductile. Those of you that replace grade 5 with grade 8 let us know if they disappear (break and fall out). The cyclic loads on hitches may promote cracking with grade 8. I would stay with grade 5. Just an opinion.
Re: Frame Bolts Reply #10 – August 26, 2021, 09:37:44 am "Depending on the local stock, Home Depot or Lowes should have the bolts along with HEAVY WASHERS and nyloc lock nuts."Greg, I second what Larry recommends. It is truly the best way to go. I did the grade 8 replacement with our 2010 RB shortly after bring it home 11 years ago and the grade 8 bolts, washers & nuts held up well with no loosening ever. Since the slots are better with the newer chassis (including our new 2021 RB (which I have also changed over to grade 8 hardware) I have used grade 8 flat washers over the slots which don't bend or cup in the slots. Being over cautious, I added red threadlock to the nuts and tightened to 140ft. lbs. with an impact wrench. We have towed our Jeep Cherokee (4400 lbs.) from Florida to your CA home and back (7600 miles) on quite a few sketchy back roads along the way with no loosening of the current upgrade. You also might want to check an Ace Hardware for the grade 8 hardware if you need to. Our Ace in Brooksville had a good selection in both thread patterns. I chose the fine threads. Our coach already came with grade 8 bolts that held the hitch receiver to the bumper plate. Mike 2 Likes
Re: Frame Bolts Reply #11 – August 27, 2021, 10:01:23 pm As a metallurgical engineer in a previous life, I have between nil and zero concern about the bolts breaking. The material that is used is much more durable than grade 5. I changed out all of my grade 5 bolts/nuts/ washers with grade 8 and Then torqued to 125 ftlbs. Doubt that is going to move.
Re: Frame Bolts Reply #12 – August 27, 2021, 11:01:25 pm With the grade 8 changeover, is it a good idea to use Threadlocker?
Re: Frame Bolts Reply #13 – August 28, 2021, 01:18:22 am Quote from: HiLola - August 27, 2021, 11:01:25 pmWith the grade 8 changeover, is it a good idea to use Threadlocker?I prefer to use nyloc nuts instead of standard nuts with thread locker. Nylock nuts have a nylon insert that prevents the nut from moving, even if the the torque is reduced or eliminated by parts settling into each other. This prevents a loose nut from unscrewing and falling off, something the Factory hardware can do and has done, BTDT.Nylocs can be tightened again without having to apply new thread locker, convenient for the annual towing equipment torque check. Years ago, we came close to losing the Jeep when the Factory supplied bumper hardwared failed, switching to grade-8 hardware, with its greater clamping power, has eliminated loosening problems.Larry
Re: Frame Bolts Reply #14 – August 28, 2021, 11:53:24 am Thank you everyone for sharing a wealth of knowledge. I have learned a great amount of knowledge on LDs, and I don't even own one yet.
Re: Frame Bolts Reply #15 – August 28, 2021, 04:31:25 pm After a trip to Home Depot and Tractor Supply (I forgot to try Ace Hardware), I rounded up most of the grade 8 hardware to upgrade the 'frame bolts'. Couldn't find the nyloc nuts but they are available on Amazon. I did find Grade 8 regular nuts and lock washers so purchased some just in case. The last thing to find are the extra thick flat washers. I noticed the existing thick washers are marked "MCX". Can I just reuse them if in good condition? Not knowing what MCX means, I searched and found this:Extra Thick Grade 8 Washers | Grade 8 Washers | Wrought WasherThe existing washers are just over an inch in diameter so I think they fall under the S.A.E. dimensions on the chart in the link. Wondering if they should be larger in diameter to match the other flat washers?
Re: Frame Bolts Reply #16 – August 30, 2021, 10:28:38 am Greg,Last week I visited my favorite store, Marshall's Industrial Hardware, here in San Diego. I bought the 1/2" X 13tpi X 2 1/2" bolts, lock washers, and fender washers, all grade 8, and matched the fender washers to the size I removed from the Lazy Daze. The original washers were deformed to the slot openings and top curvature in the frame extension and the bumper/hitch attachment, but the stock attachments were tight and secure with original red Locktite holding the nuts.I had some flat 2 1/2 inch stock steel and planned to make backing plates as Larry did, but decided that the flat stock was as likely to bend as the original washers. Instead, I doubled the grade eight washers on the nut side of the bolt with a single washer on the head side. Torque to 105ft/lb. with red Locktite and one more job finished before we take off in October. Ball joint Zerk fittings are next. Rear sway bar bushings and an oil change and we will be ready to go!Harold 1 Likes
Re: Frame Bolts Reply #17 – August 30, 2021, 02:05:52 pm Quote from: Blueox25 - August 30, 2021, 10:28:38 amI had some flat 2 1/2 inch stock steel and planned to make backing plates as Larry did, but decided that the flat stock was as likely to bend as the original washers. Instead, I doubled the grade eight washers on the nut side of the bolt with a single washer on the head side. Torque to 105ft/lb. with red Locktite and one more job finished before we take off in October. I used 1/4" flat stock, for the plates and it is still as flat as the day it was installed, if anything, it is overkill. The bolts have never loosened over the past 14 years. The washer method should work fine too.Sandwich plate | New sandwich plate replacing thin washers. … | Flickr Now that everyone has fixed their rear bumper attachments, take a look at the 2" hitch receiver plate.This is what the bottom of our hitch receiver plate looked like when it was removed seven years ago. Previously, I had checked the torque every year but while camping. I meet a man who worked at the steel fabrication shop that LD uses and he told me that the hardware was undersized and they had seen breakage of the bolts. New models supposedly have bigger bolts. After returning home, the plate was removed and shiny spots were found around all four bolts, indicating of the plat, caused by undersize hardwarenwith insufficient clamping power.The receiver was held to the bumper with two 3/4 inch, Grade-5 bolts, and two 1/2 inch, Grade-5 bolts.It wasn't enough. The photos show the connection between the bumper and receiver. The dark, shinney spots are where the movement was occurring. All the hardware was upsized and replaced with grade-8 hardware.From my Flickr site.Hitch receiver upgrade | Flickr"The receiver is held to the bumper with two 3/4 inch, Grade-5 bolts, and two 1/2 inch, Grade-5 bolts.It isn't enough. The photos show the connection between the bumper and receiver. The dark, shinney spots are where the movement was occurring. All the hardware was upsized and replaced with grade-8 hardware.After bolting the receiver to the bumper, several inch-long welds were made around the perimeter, to lock the receiver in place. The welds are placed where they can be easily cut if future repairs are needed.All four original bolts were torque to their SAE specs (78-lbs and 257-lbs) and were check again just before disassembly.Looking at shiny spots on the bumper, receiver, and bolts, it's obvious, the bolts do not provide enough clamping force to prevent movement.Most of the movement occurred around the two 1/2 inch bolts. Odd thing is both the bumper and receiver were already drilled for 9/16 inch bolts. Someone goofed this up.All the hardware was upgraded to Grade-8 with the 1/2 inch bolts upgraded to 9/16 inch. Nylon nuts and grade-8 washers were used to prevent loosening.Two 1-1/2 inch wide X 1/4 thick steel straps were cut and drilled for use of reinforcing washers, used on the receiver bolts to sandwich the bumper and receiver together.The new hardware was torqued to 150-ft/lbs and 380-ft/lbs, a big increase over the stock hardware.After the hitch was reinstalled, I made four, short welds around the perimeter to permanently secure the hitch but with the ability to be removed, after grinding the small welds."Towing a Jeep for ten of thousands of miles since, nothing has loosened or needed any attention other than the annual torque check.Larry
Re: Frame Bolts Reply #18 – September 10, 2021, 02:35:16 pm Just an update. Completed the swap over of the 1/2” frame bolts to grade 8. I’d like to say it was a piece of cake (POC) but it was more of a PITA. It’s pretty tight under there and was made worse because the LD front wheels are higher right now which makes the back end lower, thus less space to work in. The passenger side bolts were relatively easy because I was pulling down with the torque wrench. Pushing up on the driver side was much more difficult. It’s not easy to reach 120 ft. lbs. when you only weigh 150 lbs. (note to self- work out more)!
Re: Frame Bolts Reply #19 – September 10, 2021, 03:58:46 pm Greg,Working out is hard work and a slow way to gain weight.My vote is to enjoy eating more!Push ups and pull ups vs. pizza and ice cream?Harold 3 Likes
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