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Author Topic: Is it okay to replace fine thread frame bolts with coarse thread?  (Read 2515 times)
belfert
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« on: September 11, 2007, 07:11:14 AM »

Some of the radiator framework in my bus is held down with fine thread flanged frame bolts.  I lost two of these bolts somewhere along the way.  Hardware stores and auto parts stores only have the coarse threaded version of these bolts.  I've tried MCMaster-Carr, MSC, and Fastenal to no avail.  There are lots of places online that have these, but I would have to buy between 100 and 1000 of them.

Am I going to have issues going from fine thread bolts to coarse thread bolts?  The bolts are 1/2-20 now.
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maria-n-skip
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« Reply #1 on: September 11, 2007, 07:15:45 AM »


  I am suprised NAPA doesn't have fine thread bolts. Some of our hardware staores have a good selection
 of bolts if you don't need anything harder than grade 5.  The Cat dealer in most areas have a good selection
  of grade 8 bolts. (and FINE thread is used quit a bit)

    To use coarse you should retap and at best it will be a poor hold factor.


    FWIW
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FloridaCliff
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« Reply #2 on: September 11, 2007, 07:18:26 AM »

Brian,

Call a long established hardware store.

I have two old style stores in my general area and they carry everything.

New blister pack stores don't come close.

Cliff
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belfert
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« Reply #3 on: September 11, 2007, 07:51:19 AM »

The bolts go through the frame, not into it.  There is a nut on the end of the bolt.  Some places call them frame bolts and others just call them flange bolts.

The bolts are grade 8 flange bolts.  The nuts also have flanges with no washers used.  Finding fine thread grade 8 bolts is not an issue.  The flange part is the issue.

I've been to several old fashioned hardware stores and a few auto parts stores and they only have the frame/flanged bolts in coarse thread.  I did think of one other hardware store that might possibly have them, but not sure I want to drive all the way over there.
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maria-n-skip
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« Reply #4 on: September 11, 2007, 08:07:38 AM »



 Try these people


 Fastenal Co - more info »
7521 Washington Ave S, Edina, MN
(952) 941-9566
Category: Nuts & Bolts

They report in stock    1/2-20 1.5 long grade eight


    Hope this helps

   Skip
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belfert
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« Reply #5 on: September 11, 2007, 08:18:07 AM »



 Try these people


 Fastenal Co - more info »
7521 Washington Ave S, Edina, MN
(952) 941-9566
Category: Nuts & Bolts

They report in stock    1/2-20 1.5 long grade eight

Do you have a Fastenal part number?  The web site when listing flanged bolts jumps from 1.25 inch to 2.25 inch.  I'm guessing most stores would not stock this, but I don't have a problem ordering the bolts.

The Fastenal website used to have catalog pages in PDF for each item, but not anymore that I can see.  I was hoping to look at the catalog pages to see if the website is just screwed up.
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maria-n-skip
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« Reply #6 on: September 11, 2007, 08:28:48 AM »

  Since I'm not sure of what length you need........

1/2-20x2 G8 FLG PO
Sku: 19831
Package Quantity: 1
Manufacturer: Fastenal Approved Vendor In-Stock Item  $1.01


1/2-20x1.5 G8 FLG PO
Sku: 19829
Package Quantity: 1
Manufacturer: Fastenal Approved Vendor In-Stock Item  $0.91


1/2-20x1.75G8 FLG PO
Sku: 19830
Package Quantity: 1
Manufacturer: Fastenal Approved Vendor In-Stock
Limited Locations  $0.96

1/2-20 x 2.5 Hex Flange Bolt Grade 8, Phos & Oil
Sku: 0142799
Package Quantity: 1
Manufacturer: Fastenal Approved Vendor In-Stock
Limited Locations  $1.49


1/2-20x1.25G8 FLG PO
Sku: 19827
Package Quantity: 1
Manufacturer: Fastenal Approved Vendor In-Stock
Limited Locations  $1.02


1/2-20 x 3 Hex Flange Bolt Grade 8, Phos & Oil
Sku: 0142801
Package Quantity: 1
Manufacturer: Fastenal Approved Vendor Lead Times Vary  $2.16


1/2-20 x 2.25Hex Flange Bolt Grade 8, Phos & Oil
Sku: 0142798
Package Quantity: 1
Manufacturer: Fastenal Approved Vendor Lead Times Vary  $1.40

 IF you need something shorter than listed you can do an old trick of putting a throw away nut on then then cutting
 it with a hand grinder clean up the end and back the nut off.....

Hope this is helpful

 Skip

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Utahclaimjumper
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« Reply #7 on: September 11, 2007, 08:30:43 AM »

A flanged bolt is no different than a bolt with a flat washer, try washers and lock nuts.>>>Dan
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belfert
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« Reply #8 on: September 11, 2007, 08:43:04 AM »

  Since I'm not sure of what length you need........

1/2-20x1.5 G8 FLG PO
Sku: 19829
Package Quantity: 1
Manufacturer: Fastenal Approved Vendor In-Stock Item  $0.91

Thanks much.  The program on the Fastenal web site that helps narrow down the 400+ choices for flange bolts didn't show the 1.5" bolt.  I actually downloaded the entire catalog in PDF and was about to look at it.

I would much prefer to use the same bolts as original instead of trying something different.  The manufacturer probably choose flange bolts for a reason as I think they cost more than a bolt and washer.
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kyle4501
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« Reply #9 on: September 11, 2007, 09:57:39 AM »

Fine thread bolts are stronger than the coarse thread of the same size (due to the larger diameter at the root of the thread & other things). Is the joint highly stressed? Do you need all the strength of a fine thread? The manuf may have used them as a commonality thing, maybe purchasing screwed up, maybe the vendor was out of stock of the regular bolts & substituted a better bolt to make delivery, maybe . . . .

Does the flange/ frame bolt have serrations under the head? If so, this is a real help in reducing loosening due to vibrations. If it were me, I'd use standard grade 8 fine thread bolts with the all steel lock nut to eliminate the loosening issue ( I'd also use the GR8 flat & lock washers too).
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« Reply #10 on: September 11, 2007, 12:03:38 PM »



Thanks much.  The program on the Fastenal web site that helps narrow down the 400+ choices for flange bolts didn't show the 1.5" bolt.  I actually downloaded the entire catalog in PDF and was about to look at it.

I would much prefer to use the same bolts as original instead of trying something different.  The manufacturer probably choose flange bolts for a reason as I think they cost more than a bolt and washer.

Brian, it sounds like you're caught between what you want to use and what's available.  You may have to use what's available.  You said you lost two.  How many are remaining?  I wonder if two bolts with washers would be OK, since you've got all the rest?  Perhaps the manufacturer used flanged bolts 'cause they're easier and quicker to install.  My MC-8 had them to hold the fiberglass wheel well liners in.  I can guarantee you that the washers and bolts I used will hold that fiberglass liner in just fine.  I realize you're talking about a heavy radiator, but with a grade 8 washer, bolt, and lock washer, I'm sure that radiator won't be going anywhere any time soon.  If you're still not sure, pop a small spot weld on each washer to the bolt and make a flanged bolt.  I can't see how this would be an issue.

David
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belfert
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« Reply #11 on: September 11, 2007, 12:09:50 PM »

The radiator support is bolted to the frame rail with six of these flanged bolts with flanged nuts.  Four are on the main support and two are on an angled brace welded to the main support.  Overkill probably.

I think I'll probably just use the coarse threaded bolts.  I still need to find the two nuts I dropped on the ground.  I will probably need a magnet to find the nuts as I crawled under there on my belly and could not find them.  I wish I had a nice concrete driveway instead of river rock, dirt, and leaves.
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DavidInWilmNC
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« Reply #12 on: September 11, 2007, 12:28:26 PM »

I wish I had a nice concrete driveway instead of river rock, dirt, and leaves.

I'll trade you!  I've got sand, a bit of dead grass, some leaves, and oil (it's a 2-stroke, remember!).  The worst is the sandy soil; my tires sink a couple of inches within a week or two!

Daviid
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« Reply #13 on: September 11, 2007, 01:34:07 PM »

You guys are making me feel bad, Ive got a 40X45 garage with a spotless floor and still loose things.>>>Dan
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TomC
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« Reply #14 on: September 11, 2007, 04:30:06 PM »

For supporting the radiator, course will be fine.  I like to double or jam nut each bolt.  If it is a frame structural point, only grade 8 fine should be used.  Good Luck, TomC  PS-Home Depot has fine bolts and nuts. 
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belfert
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« Reply #15 on: September 11, 2007, 06:01:01 PM »

I found one of the the bolts when putting things back together so only missing one bolt now and some nuts that fell on the ground.  I ended up buying the coarse thread bolts at the hardware store since I can't find anyone who has the right bolts in fine thread with the proper jam nut unless I want 100+ of them.

The nuts that I bought with the new bolts are lock/jam nuts and they were hard to get tightened on the bolts.  The original nuts were also jam/lock nuts and are somewhat hard to get tight.
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« Reply #16 on: September 12, 2007, 05:46:16 AM »

Brian: I think this is the first post where you mentioned lock nuts. I think you are over concerned about the replacement bolts when you have no concern about reusing lock nuts. Depending on the type, many are a one use and then throw away, while ones like on an Allison output shaft can be used up to three times.
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« Reply #17 on: September 12, 2007, 08:25:44 AM »

I learned long ago when doing a take apart project to use a tuperware bowl or old coffee can for the nuts and bolts.  Believe me it will save you alot of time and aggravation.  Good Luck, TomC
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belfert
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« Reply #18 on: September 12, 2007, 08:36:36 AM »

Brian: I think this is the first post where you mentioned lock nuts. I think you are over concerned about the replacement bolts when you have no concern about reusing lock nuts. Depending on the type, many are a one use and then throw away, while ones like on an Allison output shaft can be used up to three times.

The frame bolts and nuts that I reused still seem to have plenty of lock left in them.  The nuts are all metal and they are still very difficult to tighten so they seem to still lock okay.

I would be happy to replace all of the frame bolts if I could FIND any.  Every place that has these in fine thread has a minimum of 100 and in many cases minimums of 300 to 2000.  Fastenal, McMaster-Carr, and MSC all have the bolts, but not the flare lock nuts.  Just about every hardware store has these in coarse thread.
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Dallas
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« Reply #19 on: September 12, 2007, 10:14:12 AM »

Brian....

Check with Mac's Hardware, even though there isn't one in the Cities, that's where the main offices are.

They sell bolts and nuts of all shapes sizes sorts and kinds by the pound. Possibly they'll make you a good deal.

I think the closest store to you is Detroit Lakes, but, Hey, you probably need a break anyway.

MAC'S INC. MINNEAPOLIS, MN OFFICE:
8816 7th Ave. N.
Golden Valley, MN 55427
(763)544-0588 • Fax: (763)544-0607
(800) 390-8265
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belfert
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« Reply #20 on: September 12, 2007, 10:53:21 AM »

Detroit Lakes would be a really long drive.  It would be somewhere around 4 to 5 hours each way.  Moorhead would be a bit closer I think, but still a long drive.

I'm not sure calling would be worthwhile as most folks at hardware stores get confused once you get beyond standard nuts and bolts.
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« Reply #21 on: September 13, 2007, 03:58:28 PM »

Belfert,

No!

John
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kyle4501
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« Reply #22 on: September 13, 2007, 05:15:26 PM »

Belfert,

No!

John

OK, I'm a little slow, what did I miss?  Huh
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« Reply #23 on: September 13, 2007, 05:36:05 PM »

My personal opinion is that you could put six 1/2 X 13 grade 2 bolts in and tighten them with a pair of pliers they would probably last as long as you own the coach.

I don't think you have six 1/2 X 20 grade 8 bolts holding in your 400 HP engine. That size and grade have a tremendous amount of strength in both tension and shear. If you are only missing two in your rad frame, put in a couple of bolts and snug them up and get on with more important things.

As end users, we don't know why a manufacturer used a particular component although the usual reason is cost. If they can use the same fastener in multiple places they get a bigger volume discount that more than makes up for using a better bolt than ordering a smaller quantity of two different bolts.

Years ago I ordered some 1 1/4" long oval head Phillips Stainless bolts from MCI and was shocked at the price. When I checked the price book, I found that I could have ordered 1 1/2" for less than half price. This was a simple case of the relative volume they used of each length.
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belfert
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« Reply #24 on: September 13, 2007, 05:55:44 PM »

My personal opinion is that you could put six 1/2 X 13 grade 2 bolts in and tighten them with a pair of pliers they would probably last as long as you own the coach.

I don't think you have six 1/2 X 20 grade 8 bolts holding in your 400 HP engine. That size and grade have a tremendous amount of strength in both tension and shear. If you are only missing two in your rad frame, put in a couple of bolts and snug them up and get on with more important things.

You're absolutely right on this.  I gave up looking for fine thread bolts a few days ago and just replaced most of the bolts with new coarse thread ones that any good hardware store stocks.  Not cheap at $3 for the bolt and nut, but what is cheap on these buses?
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Stan
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« Reply #25 on: September 13, 2007, 06:02:22 PM »

Is there only one hardware store in town. I have a choice of three  in a town of about 15000 people and they all sell bolts by the pound. Grade 5 bolts, nuts, flat and lock washers $1.89/pound. Same thing in Grade 8 is $2.89/pound. The cheapest thing I bought for a bus.
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belfert
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« Reply #26 on: September 14, 2007, 07:51:28 AM »

Is there only one hardware store in town. I have a choice of three  in a town of about 15000 people and they all sell bolts by the pound. Grade 5 bolts, nuts, flat and lock washers $1.89/pound. Same thing in Grade 8 is $2.89/pound. The cheapest thing I bought for a bus.

These are special grade 8 bolts and nuts with flared heads.  The nut is also an all metal lock nut while having the flare.  These are not standard grade 8 fine thread bolts.

They are also known as frame bolts.  I went to three auto parts stores, a truck parts place, and numerous hardware stores looking for these in fine thread.  They all had these bolts in coarse thread.  I also went to Fastenal and checked McMaster-Carr.  McMaster and Fastenal had the bolts in fine thread, but not the special lock nuts.  I also checked numerous web sites, but they all wanted to sell a minimum of 100 with minimums of 300 and up more common.
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« Reply #27 on: September 14, 2007, 08:09:53 AM »

Brian: I was referring to your paying $3.00 for each bolt and nut at the local hardware.
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RJ
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« Reply #28 on: September 14, 2007, 08:13:27 AM »

Brian -

I know I'm jumping into this thread a little late, but this might help for "next time":  Ask at an auto body shop if there's a company in town that supplies them with their specialized nuts, bolts and washers.

Here in Fresno, there's a little "hole-in-the-wall" office in the middle of one of those strip industrial parks that has a HUGE assortment of automotive and ag equipment fasteners of all types, from serrated flange nuts and bolts to the large fender washers - they even carry the clips to mount door panels.  This place was referred to me by a friend who owns an auto body shop, and what a great tip it has turned out to be.

I've often found what I've been looking for at this place, after exhausting the big box and mom & pop hardware stores.  So check into it, I'm sure there's something similar in the Twin Cities area.  (And no, this isn't a Fastenal branch, altho we do have one here in Fresburg.  This is an independent.)

FWIW & HTH. . .

 Wink
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RJ Long
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