Rolok Shock!

Topic: Rolok Shock! (Read 1341 times) previous topic - next topic

Rolok Shock!

August 10, 2012, 12:09:57 pm

I had called FOT parts (Mike) requesting pricing and to order some Roloks for my bulkhead repair project (These are to replace some of the ones that go into the basement compartment dividers from underneath) and was pleasantly surprised at the quote for $.69 apiece. I ordered forty thinking I would have some spares... well today, Mike called me back and said "I have some bad news for you...". It turns out that the new pricing is $4.67 (might be a few cents off...). After I picked up my jaw off the floor, I asked if the bulkhead repair kits with the Roloks still available for $30 or so, but sadly not. Turns out that Foretravel had last bought Rolkos in the 90's and had bought about 40,000 of them, and had recently run out. The new current owners would only allow the purchase of 10,000 and so some of the price break is gone, but that also the price had gone up. Well, bottom line is our price has gone up nearly sevenfold! He was very apologetic and told me where they source them in case I wanted to price them myself (HRS Fastenters in Arlington). I had previously asked if 3/8"X3" upsized Rolkos are available and Mike said that they only stock the 5/16"X3". So I tried to request a quote for some 3/8"X3"X16 threads per inch from HRS's website, but their form submission doesn't work (terrible website, BTW).
Anyway, be advised the cost of the standard Foretravel Roloks is up, way up!

Anybody who finds other sources where you don't have to buy thousands, please post!
Don

Re: Rolok Shock!

Reply #1 – August 10, 2012, 01:05:01 pm

Craig,

I called a bunch of fastener suppliers searching for Roloks. They are only available in a larger order. One fellow explained that they are used when a manufacturer does mass production as they are quick and easy to install. As you could see from the photos, they don't seem to have any rust preventative coating. You might be better served with the Tap-Flex fasteners at Tap-Flex Thread Forming Structural Screws - Tanner Bolt & Nut Corp. They are specially coated, roll their threads and are very strong. Only negative is 2 1/2 inches is the maximum length and 3/8x16 is the smallest size. 2 1/2" should be enough to reach through the angle iron, the bulkhead and tap both sides of the 1 1/2" square tube.

My front and back bulkheads looked like new with only a couple of broken bolts (I thought). Check the photos for what was between the bulkhead and the angle iron. The torque wrench test is ONLY good to check for broken bolts, not to check on the condition. Many of mine were rust frozen solid and broke off when I tried to remove them. Just because they pass the torque wrench test is NO indication as to their strength or condition.

After pulling seven or eight in a row, I forced the angle iron out with a flat chisel and a hammer. Easy to do. I then took a Sawsall with a long blade and clean the area the best I could. You can see the large chunks that came off the angle iron in the photos. One was huge and half as thick as the angle iron itself. I will use my sandblaster to clean the remaining rust out and spray galvanize before using a primer.

Since I needed to make a 1000 mile trip, I tapped the near side of the square tubing to 3/8" and installed grade 8 bolts. In one spot under the propane tank, I could install all the way through and was able to torque to 47 ft lbs without deforming the square tube.

I have 3 inch 316 stainless bolts and will do the conventional repair all the way through when I have time. I am doubling the number so the strength will be there. They came in a box of 50 so it will work out perfectly.

Check the photos! All this rust from a very clean underbelly with no time in the northern states.

Pierce

Re: Rolok Shock!

Reply #2 – August 10, 2012, 01:30:21 pm

I spoke with Semblex technical support, the manufacturer of the Rolok. They indicated that Rolok bolts can be replaced with any 5/16-18 bolt including competitors self tap bolts. The Rolok is unique such that it requires lower driving torque than other self tap bolts. They indicated that they would sell bolts to me but their minimum order was thousands.

I phoned Foretravel last week and got the $0.70 price per Rolok and did not order them yet.

I decided to use 3/8-16 2.5 inch grade 5 bolts which are available locally and are plated. I purchased a 4 inch long 3/8 by 16 tap. I am drilling holes and cutting threads yesterday, today and more next week. At almost $5.00 per bolt for Rolok bolts, I will continue using 3/8 plated bolts. I am going to attempt to purchase some roll-thread self taping 3/8 bolts on-line because they are not available locally.

The reason for using 3/8 bolts is that I am not comfortable with just applying 220 lb inches of torque each way and believing that the bolts that held are good. I decided to attempt to remove all bolts and replace or at least re-torque. I had one bolt which had self loosened and could be easily removed. The Rolok specifications are tighten 120, torque 250, failure 450+ (pound inches). Based on this information, it should be safe to attempt removing at 30 foot pound (360 lb inches). I found that three bolts near the center on the rear just broke at about one inch long (inside the square tube). I stopped at this point because I decided to install some good bolts on each end before attempting removeal of more center bolts. The Rolok bolts which broken showed cracks which had reduced the effective diameter of the bolt. The clean break was no more than half the area of a new bolt. Larger bolts with the same corrosion will probably still be removeable.

I am convinced that 5/16 bolts are strong enough on install but not strong enough to hold for decades.

Bolts are not expensive, but bulkhead failure is.

Re: Rolok Shock!

Reply #3 – August 10, 2012, 02:25:11 pm

Pierce,
The 2 1/2" 3/8" bolts appear to be available only in quantity as well (Carton of 500 for about $278). I am only going to buy enough Roloks to replace the front bulkhead bolts as a precaution. I have already removed all of them (a few at a time... still leaving Roloks in to support the 1/4 tank of Diesel and the 42 Gal propane tank) and cleaned and inspected them. Only one failure on the outside curbside bolt which was broken just before the back wall of the tube or at about 1 3/4" in. Since the out side bolts on both sides terminate inside the longitudinal outer most square tubing, it presents a challenge, but I have a plan... The reason I am replacing the front ones with Roloks instead of conventional bolts of the same size and thread pitch is that conventional bolts that are fully threaded are only available in grade 2 (so called "tap bolts"). The bolts need to be fully threaded so as to grab both walls of the transverse bulkhead tube. Although all but one of the Roloks came out intact and cleaned up nicely with a wire wheel, as well as went back in the holes and tightened up nicely, I want to have pristine bolts up there just in case there is some hidden cracking I can't detect without a microscope.

The Roloks that go up through the belly skin and through inch and a half square tubing into the basement compartment vertical dividers are a different matter because the first inch and a half (plus the thickness of the belly skin) of the threads aren't needed. This also means that the receiving thread of the compartment dividers is limited to just one wall of the tubing because the screws (Roloks), being only 3" long don't even quite reach the far side of the tubing. For those, I will replace the questionable Roloks conventional 5/16"X2 1/2" Grade 8 bolts.
The exception to that is the short vertical divider between the waste tanks and the fresh water tank because they were all questionable (most of them weren't doing much holding). These I will tap to 3/8"X16 with a thread rolling tap that I have because I can move it slightly to one side and access the bottom of that tubing. At least that is the current plan... Not too concerned about the holding power there because my basement framing under the tanks is now so much more robust than it was, it doesn't really need help from the divider to support the weight of the tanks.
Don

Quote from: Pierce & Gaylie Stewart – August 10, 2012, 01:05:01 pm

Craig,

I called a bunch of fastener suppliers searching for Roloks. They are only available in a larger order. One fellow explained that they are used when a manufacturer does mass production as they are quick and easy to install. As you could see from the photos, they don't seem to have any rust preventative coating. You might be better served with the Tap-Flex fasteners at Tap-Flex Thread Forming Structural Screws - Tanner Bolt & Nut Corp. They are specially coated, roll their threads and are very strong. Only negative is 2 1/2 inches is the maximum length and 3/8x16 is the smallest size. 2 1/2" should be enough to reach through the angle iron, the bulkhead and tap both sides of the 1 1/2" square tube.

My front and back bulkheads looked like new with only a couple of broken bolts (I thought). Check the photos for what was between the bulkhead and the angle iron. The torque wrench test is ONLY good to check for broken bolts, not to check on the condition. Many of mine were rust frozen solid and broke off when I tried to remove them. Just because they pass the torque wrench test is NO indication as to their strength or condition.

After pulling seven or eight in a row, I forced the angle iron out with a flat chisel and a hammer. Easy to do. I then took a Sawsall with a long blade and clean the area the best I could. You can see the large chunks that came off the angle iron in the photos. One was huge and half as thick as the angle iron itself. I will use my sandblaster to clean the remaining rust out and spray galvanize before using a primer.

Since I needed to make a 1000 mile trip, I tapped the near side of the square tubing to 3/8" and installed grade 8 bolts. In one spot under the propane tank, I could install all the way through and was able to torque to 47 ft lbs without deforming the square tube.

I have 3 inch 316 stainless bolts and will do the conventional repair all the way through when I have time. I am doubling the number so the strength will be there. They came in a box of 50 so it will work out perfectly.

Check the photos! All this rust from a very clean underbelly with no time in the northern states.

Pierce

Re: Rolok Shock!

Reply #4 – August 10, 2012, 02:32:05 pm

Torqued tested my roloks yesterday. Two broken in the rear one in the front. Was unable to get a feeler gauge into the joint at any location. Will hole saw to gain access then double nut to remove roloks. Will be using 5/16" x 3" grade 8 bolts threaded into the roloks cut threads and torqued to 22 ft lbs .then a washer and jam nut inside the access hole torqued to 22 ft lbs using loctite 242 on the threads.. Gam

Re: Rolok Shock!

Reply #5 – August 10, 2012, 03:05:13 pm

Don,

Assuming that a supplier would not be willing to break a box of 500 Tap-Flex bolts, that is still only about $0.50 each. Even if one had to spend the $278, it would be only a tiny fraction of what a bulkhead failure/repair would cost.

Quite right about the strength of all thread/tap bolts at a grade 2 level. The 316 stainless all thread are much stronger than 18-8 stainless and WHEN DOUBLED up, will give more surface, a stronger clamp and tensile strength than even grade 8s.

Here are the figures for all grades:

3/8"-16 in grade 2 4250 lbs clamping/proof load and 5750 lbs tensile strength
grade 5 6693 lbs " " 9300 lbs " "
grade 8 9300 lbs " " 11,600 lbs " "
316 3/8-16 tap bolts 5100 lbs " " 10,900 lbs " " (stainless)

The Tap-Flex 3/8"-16 are grade 5, are thread forming and have a Silver Stalgard® GB coating against corrosion.

Good you noted that all taps are not created equal. Some cut and some roll the threads with rolling the preferred method for max holding.

If the angle iron is not cleaned, protected and continues to exhibit rust jacking, it will break any bolt that could be installed over a period of time.

Pierce

Re: Rolok Shock!

Reply #6 – August 10, 2012, 03:21:24 pm

Pierce,
Just to completely confuse this subject, have you considered using the Heli-Coil method. I am guessing the material is not thick enough to use the Heli-Coil, however, Heli-Coils provide a stronger thread (due to the larger diameter), but just wondering if that has been considered ?
I know from experience on aluminum, replacing a standard threaded bolt hole is much stronger once you insert the Heli-Coil (correctly).
Maybe using a longer bolt and using a thick nut plate for the Helicoil, would allow a smaller diameter bolt, but be a super anchor for the nut.?
See, told you I would mess up the thread.

Dave M

Re: Rolok Shock!

Reply #7 – August 10, 2012, 05:23:56 pm

Gam,
Regarding using the Rolok cut threads... did you find a source for grade 8 fully threaded bolts? If you have, sounds like a good plan (and please tell me where you found them!). If not, remember that if you can't use the threads on both faces of the the transverse tubing, you will be exerting some crushing force on the square tubing. I did some testing on scrap and found that it will crush easier than expected.
Don

Quote from: gam – August 10, 2012, 02:32:05 pm

Torqued tested my roloks yesterday. Two broken in the rear one in the front. Was unable to get a feeler gauge into the joint at any location. Will hole saw to gain access then double nut to remove roloks. Will be using 5/16" x 3" grade 8 bolts threaded into the roloks cut threads and torqued to 22 ft lbs .then a washer and jam nut inside the access hole torqued to 22 ft lbs using loctite 242 on the threads.. Gam

Re: Rolok Shock!

Reply #8 – August 10, 2012, 06:02:25 pm

Quote from: Dave M – August 10, 2012, 03:21:24 pm

Pierce,
Just to completely confuse this subject, have you considered using the Heli-Coil method. I am guessing the material is not thick enough to use the Heli-Coil, however, Heli-Coils provide a stronger thread (due to the larger diameter), but just wondering if that has been considered ?
I know from experience on aluminum, replacing a standard threaded bolt hole is much stronger once you insert the Heli-Coil (correctly).
Maybe using a longer bolt and using a thick nut plate for the Helicoil, would allow a smaller diameter bolt, but be a super anchor for the nut.?
See, told you I would mess up the thread.
Dave M

Dave,

I have used Heli-Coils on VW cylinder heads. They are stainless steel and do add a lot of area so would be much more resistive to pulling out over the stock sized bolt. The problem is the square tubing only has a wall thickness of .125 so would be too thin in this application as I see it. By either enlarging the stock hole or drilling a new hole all the way through and then installing a washer and nut with access from a hole drilled from the bottom of the coach looks pretty fool proof. I torqued the one grade 8 under the propane tank (where there is already a channel allowing access to the other side of the 1 1/2" square tubing to install a nut/washer) up to the 47 lb spec without deforming the tubing. With the 316 stainless bolts, the torque will only be around 247 inch lbs (or 20.6 ft lbs) (dry) as I remember so the chance of crushing the tubing are low.

When someone cross threads spark plugs, Heli-coils can save a cylinder head for sure. Like you said, if installed correctly. Also many owners were used to cast iron heads and used the same torque on the aluminum heads and pulled the threads out. Used a lot in VW, Porsche and Corvair engine cases where the studs pull out.

Pierce

Re: Rolok Shock!

Reply #9 – August 10, 2012, 09:10:09 pm

Pierce,
Total agreement, like I mentioned, thought might screw up a thought for some.
Cheers
Dave M

Re: Rolok Shock!

Reply #10 – August 10, 2012, 09:55:12 pm

mC Master Carr has fully threaded grade 8 5/16" x 3" bolts for a buck each. Using the threads on both faces is why I'm going to try this. Haven't heard of a rolok that stripped it's thread, and that should be it weakest point. Gam

Re: Rolok Shock!

Reply #11 – August 11, 2012, 02:42:34 am

Quote from: gam – August 10, 2012, 09:55:12 pm

mC Master Carr has fully threaded grade 8 5/16" x 3" bolts for a buck each. Using the threads on both faces is why I'm going to try this. Haven't heard of a rolok that stripped it's thread, and that should be it weakest point. Gam

Expect your new tap bolts will do the job well for you. Good price too. Years of embrittlement, stress and erosion from rust jacking have taken their toll on all original bolts.

Your two way torque plan sounds very reasonable. Threads should hold fine on the .125 x 2 wall tubing I would think. Before I drilled one hole through, I torqued until I got a failure on the first wall at about 27 ft lbs.

Pierce

Re: Rolok Shock!

Reply #12 – August 11, 2012, 12:10:39 pm

That is a good find! I had looked at McMaster-Carr but couldn't find this when I was looking before. At a fifth the cost of Roloks, a bargain! The 3" size is the sweet spot as the 3.5" is more than twice the cost.
I had one Rolok where the hole was stripped, probably from the factory. It was the only intact Rolok in my rear bulkhead...
Don

Quote from: gam – August 10, 2012, 09:55:12 pm

mC Master Carr has fully threaded grade 8 5/16" x 3" bolts for a buck each. Using the threads on both faces is why I'm going to try this. Haven't heard of a rolok that stripped it's thread, and that should be it weakest point. Gam

Re: Rolok Shock!

Reply #13 – August 11, 2012, 01:32:06 pm

Here is the site: McMaster-Carr They not only have tap/full thread in grade 8 but also special 1000 hour coating grade 8, self locking grade 8s, grade 8s with a correct torque indicator built in, and grade 9 plus a ton more fasteners. Inexpensive and looks like no minimum order like the box of 500 other sites have.

Pierce

Re: Rolok Shock!

Reply #14 – August 11, 2012, 01:38:16 pm

It looks more and more to me like the problem with the roloks is the factory installation. Pilot holes not centered on or in line with center line of hole in angel iron. This means heads of roloks are cocked when torque. Big problem ,with shank of rolok having a bending moment where it enters the first rolled thread.this can cause a fracture of the screw at that location. Some of the roloks where over torqued or stripped on installation. Any of these things can lead to the joint being open in the area of the defective bolts. Water can then inter the joint at that location and lead to rust and rust jacking or smacking [ what they called rust jacking where I worked] . Any defective rolok leads to a higher load being placed on the adjacent roloks. Acousticant problems where totally different from the norm ,and he had far move work { great job} then I wont to think about. Gam

Re: Rolok Shock!

Reply #15 – August 20, 2012, 09:57:06 pm

Or what $200 (40ea.) worth of Roloks look like...

Don

Re: Rolok Shock!

Reply #16 – August 21, 2012, 09:45:16 am

Quote from: acousticart – August 20, 2012, 09:57:06 pm

Or what $200 (40ea.) worth of Roloks look like...
Don

Yes, that is quite a shock, especially when the only advantage of those bolts is speedier installation by the manufacturer who is using them to build something. Just drill a hole of the correct size and use a power tool to install them. No need to tap a hole for threads.

Re: Rolok Shock!

Reply #17 – August 21, 2012, 11:44:41 am

When I was originally quoted the 69 cents apiece, I thought it was a bargain because at the time I hadn't been able to locate any fully threaded grade 8 bolts to replace a lot of the under belly Roloks so I ordered 40. When Mike Grimes called me back and said "I have bad news for you...", I was literally in shock and after some hesitation (grand pause while I tried to pick up nmy jaw off the floor...) I said go ahead. About an hour later, I called back and left a message that I wanted to cancel the order or at least adjust the quantity. I never heard back until I got an email that said they were shipped...
Oh well, life goes on...
At leastI did use one to good advantage... the outer most Rolok on the passenger side (the one that terminates inside the longitudinal tubing) was the only one that was broken in the front. There was just enough room that I was able to drill the appropriate size hole alongside the broken one (still within the longitudinal tubing), and then carefully drill out the hole in the angle iron 5/16" and install a new Rolok to replace the broken one. It is hard to find a tap with that much threaded length to be able to simultaenously cut thread in both faces of the tubing. They do make their own threads quite nicely...
Don

Quote from: Jerry Whiteaker – August 21, 2012, 09:45:16 am

Yes, that is quite a shock, especially when the only advantage of those bolts is speedier installation by the manufacturer who is using them to build something. Just drill a hole of the correct size and use a power tool to install them. No need to tap a hole for threads.

Re: Rolok Shock!

Reply #18 – August 22, 2012, 07:23:47 am

Is there any reason why the Tap Flex 2 1/2" with Stalgard coating Pierce called out wouldn't work? Seems like that should be length enough to do the job or am I wrong about this?

Suspect somebody misplaced a decimal with those Rolok prices. The Tap Flex sounds better anyway.

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Rolok Shock!

August 10, 2012, 12:09:57 pm

Re: Rolok Shock!

Reply #1 – August 10, 2012, 01:05:01 pm

Re: Rolok Shock!

Reply #2 – August 10, 2012, 01:30:21 pm

Re: Rolok Shock!

Reply #3 – August 10, 2012, 02:25:11 pm

Re: Rolok Shock!

Reply #4 – August 10, 2012, 02:32:05 pm

Re: Rolok Shock!

Reply #5 – August 10, 2012, 03:05:13 pm

Re: Rolok Shock!

Reply #6 – August 10, 2012, 03:21:24 pm

Re: Rolok Shock!

Reply #7 – August 10, 2012, 05:23:56 pm

Re: Rolok Shock!

Reply #8 – August 10, 2012, 06:02:25 pm

Re: Rolok Shock!

Reply #9 – August 10, 2012, 09:10:09 pm

Re: Rolok Shock!

Reply #10 – August 10, 2012, 09:55:12 pm

Re: Rolok Shock!

Reply #11 – August 11, 2012, 02:42:34 am

Re: Rolok Shock!

Reply #12 – August 11, 2012, 12:10:39 pm

Re: Rolok Shock!

Reply #13 – August 11, 2012, 01:32:06 pm

Re: Rolok Shock!

Reply #14 – August 11, 2012, 01:38:16 pm

Re: Rolok Shock!

Reply #15 – August 20, 2012, 09:57:06 pm

Re: Rolok Shock!

Reply #16 – August 21, 2012, 09:45:16 am

Re: Rolok Shock!

Reply #17 – August 21, 2012, 11:44:41 am

Re: Rolok Shock!

Reply #18 – August 22, 2012, 07:23:47 am

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