| Author |
Message |
    
Robert Sublett (Rubisco98)
| | Posted on Friday, August 09, 2002 - 05:24 pm: | 
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I know I've seen this posted before, but did a search more than a couple of ways and came up empty. I need some recovery points on the Disco. I planned on the Jate Rings up front, but for the rear, I seem to remember seeing something about using your receiver or something. There was a picture posted if I recall correctly. Any help would be appreciated. Thanks in advance.. RS |
Robbie (Robbie)
| | Posted on Friday, August 09, 2002 - 05:33 pm: |
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you can get a receiver shackle from most any 4wheel store (~$40). like this:
or you can just use the pin that holds in the receiver shackle (careful pulling sideways as this might rub/fray your tow strap). |
Lawrence Tilly (L_Tilly)
| | Posted on Friday, August 09, 2002 - 06:20 pm: |
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RS,
Shortly after I bought it, I had my D1 pulled out of a muddy ditch with just a solid shackle pin ( > $10) like Robbie mentioned.
I was following the Defender and attacked the ditch at a fair angle, but it was more than I should have tried with the truck at the time. My saggy stock suspension and airdamn helped create a great anchor and I dug in before the front tires could start the climb out. I've always been the first to make light of my errors and told the gang I was providing "Recovery Practice". At least it was another Rover that pulled me out.
Lawrence [email protected]
96 Disco "Beowulf"
NH, USA |
Lawrence Tilly (L_Tilly)
| | Posted on Friday, August 09, 2002 - 06:21 pm: |
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Sorry, goofed the UPLOAD. Here's the pic:
 |
Robert Sublett (Rubisco98)
| | Posted on Friday, August 09, 2002 - 11:10 pm: |
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LT, that doesnt' look like it was alot of fun though amusing in the future to look at Anyhow, thanks for the info. I really don't know of any 4X4 shops really close by as I live in the burbs. Oh well, crazy pic.. Later.. RS |
Lawrence Tilly (L_Tilly)
| | Posted on Saturday, August 10, 2002 - 08:45 am: |
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Just to let you know, you don't need to find a specialty store. I actually picked the pin up at Walmart. I also see them at NAPA, Pep Boys, etc. Usually wherever they sell tow equipment or truck accessories.
If you go out with some experienced people (I usually wheel with our local Rover club) some one else is almost guaranteed to have things like this and for your first trip out they'd be happy to help (with a little teasing). But you should take whatever steps you can in advance to "make an effort". Before I bought anything else for the truck, the first thing I did was put together a recovery-bag. It's an old backpack with two 25' straps, a heavy duty chain, 1 shackle, 1 reciever pin and a pair of leather work gloves. I figure if I'm asking someone to rescue me, I don't want to say "oh, and do you happen to have everything needed to hook up to my truck also?" It's like asking someone to jump a dead battery - at least have your own cables. I also bought a HiLift in case I need to self-recover (it'll take a long time, but probably less time than walking to the nearest phone).
Lawrence [email protected]
96 Disco "Beowulf"
NH, USA |
LR Max
| | Posted on Saturday, August 10, 2002 - 01:14 pm: |
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Robert,
What city do you live in? Try http://www.4wheelparts.com/, mine here in Charlotte is a very good one and they always give you a good deal. Of course they don't really give you a good deal unless you go to the store.
I went over there earlier this week looking for OME shocks. They quoted me for 65 bucks. I gave them that "You better do better or I'll walk out" look and then they came down to 54 bucks.
Go to the website and see if there is a store in your neck of the woods. If not do a yellow pages . com search.
Another great place to buy stuff is at rallies. I bought most of my off roading equipment when 4x4 connection came to MAR and Uhwarrie Safari 2001.
Max T. |
Bill Molnar (Circekat)
| | Posted on Sunday, August 11, 2002 - 04:17 pm: |
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I recently purchased two 3/4 inch anchor shackles at a marine hardware store and a recovery strap, two inch drop hitch and mounting pin at the local wallyworld (Walmart) for my 98. My 98 has a recovery link in the front on the drivers side already installed. The recovery link extends thru the airdam.
Anyone know of any problems with this setup?
Thanks in advance.
Bill M. |
offrovn
| | Posted on Monday, August 12, 2002 - 12:34 pm: |
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Robert,
I had a question about those jate rings, or anyone else who can answer this. I was looking into those Jate Rings because I strongly feel that the recovery points on the brush bar (factory) are not strong enough. I was looking into the jate rings and a guy with a rover parts place started looking into as well and found that everyone told him that the brush bar recovery loops were strong enough, I have not done that yet and don't plan to. Does anyone have information on the jate rings like where to get them and how they like them and anything else. Does anyone have a picture. Thanks for your help. |
Lawrence Tilly (L_Tilly)
| | Posted on Monday, August 12, 2002 - 12:44 pm: |
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Bill, I have done some light pulling against that front loop on my D1 with no problem. I would probably not suggest a snatch-pull recovery, but then again it MAY be strong enough (I probably won't risk it). But for a strong, steady pull it did help me once in the past and I've pulled a few light vehicles from some snow/ice situations with it.
Lawrence [email protected]
96 Disco "Beowulf"
NH, USA |
Robbie (Robbie)
| | Posted on Monday, August 12, 2002 - 01:14 pm: |
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offrovn,
Nathan at Discount Rovers has the Jate rings.
http://www.discountrovers.com |
LR Max
| | Posted on Monday, August 12, 2002 - 02:17 pm: |
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About the Brush bar, it all depends...
My brush bar had the crap beat out of it by the previous owner. The PO had this nasty habit of running into their brick house about once every two weeks. Now, the brush bar mountings on the truck are toast. I kinda fixed them but it got bumped into a tree and messed it up again.
I would suggest that you upgrade your bolts to grade 8 bolts. If your brush bar hasn't had the piss beat out of it, it should be ok.
All it takes is for you to get up under there and look.
Max T. |
Greg P. (Gparrish)
| | Posted on Monday, August 12, 2002 - 02:40 pm: |
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The rear shackle in a receiver hitch, as I found out this weekend at Killington, makes a great protector for the plastic bumper above. I had a few ocassions where my hitch assembly hit or drug dead center over an obstacle during a hill climb, and the shackle flipped up and provided some additional coverage for my rear bumper. |
JB
| | Posted on Monday, August 12, 2002 - 03:04 pm: |
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Factory front recovery points are worthless and deadly - never trust them or be near if someone else is using them to winch or pull.
JB |
AD
| | Posted on Monday, August 12, 2002 - 06:18 pm: |
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Where is the best point to attach a JATE ring(s) to the chasis of a D2 for forward recovery? |
Lawrence Tilly (L_Tilly)
| | Posted on Tuesday, August 13, 2002 - 08:05 am: |
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JB,
Bill and I were not refering to the little tie-down rings mounted to the frame under the nose. I have an actual recovery ring which extends forward thru the front bumper (driver's side). If that's the same thing you mean is "worthless", have you personally seen someone rip one? Was it on a standard pull (like a winch) or a "snap" pull? I've both pulled my D1 and pulled other vehicles w/ the D1 using that ring and haven't had a problem. However, if you have actual experience with it breaking I'd like to hear some details so I can make an informed decision.
Lawrence [email protected]
96 Disco "Beowulf"
NH, USA |
Ken
| | Posted on Tuesday, August 13, 2002 - 08:42 am: |
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I had to use that loop thru the front bumper on a snatch pull recovery. It held with no signs of stress,not my first choice but not as bad as you hear.
P.S. you should not stand near a vehicle being recovered no matter how good your equipment. |
John Kruger (Johnnyk)
| | Posted on Tuesday, August 13, 2002 - 09:57 am: |
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Please make certain to have good recovery points.
I cannot emphasis this enough!
On Sunday a few people I know, who will remain nameless to protect their stupidity, choose a very poor recovery point. They attempted to use the front bumper. The bumper broke, sending the strap through the drivers window of the pulling vehicle. If it would have flown a few more inches to the left, it could have been fatal.
If you see someone hooking up to a poor recovery point, don't worry about stepping in and getting them to do it right.
John
www.teampb.com |
Moe (Moe)
| | Posted on Tuesday, August 13, 2002 - 10:30 am: |
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The stock recovery point seems to do ok if treated gently. Here we filled in the ruts and removed a few rocks before winching Eugene up the hill.
 |
Todd Sanders (Sanderskog)
| | Posted on Tuesday, August 13, 2002 - 10:45 am: |
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When I used to four wheel more (prior to purchasing my D1 which I have yet to get dirty) it was common practice for us to lay a heavy wool blanket over the center of the cable/recovery strap when pulling someone out. The thought being if the recovery point failed the weight of the blanket would assist in stopping something nasty from happening.
Shake your head all you want. Back in '90 when I pulled a Blazer out of a tight spot using the factory point with my '53 M38A1 the point failed and as John points out above the strap became a missle headed at my Jeep. Once it reached the point where the blanket was it stopped in its tracks and dropped to the ground harmlessly.
Does anyone else do this?
I know... shut-up and go get my truck dirty...
Todd |
Robbie (Robbie)
| | Posted on Tuesday, August 13, 2002 - 10:52 am: |
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I do that as well Todd. Never seen it in action if it works, as I have not had a strap break, but I have always wrapped a blanket, or at the very least a shirt while winching/towing. |
Paul T. Schram (Paulschram)
| | Posted on Tuesday, August 13, 2002 - 10:58 am: |
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A couple of comments.
First off Todd, your comment about the blanket is a critical component in any winching situation. I tend to use either elastic bungie cords (many of them) or, I drape my chain across the winch cable, or use climbing webbing. the elastic material will absorb much of the energy and the chain is too heavy to go anywhere but down. Recently, while doing some tree work, I had a piece of 1/2" nylon rope snap-scared me and the next time around, I took the necessary precautions and that time, broke the carabiner!
When attaching your recovery points, please do not use grade eight hardware! Grade eight hardware should only be used in situations where the pieces are being held together very tightly with no chance of impact loads, and where the loading will only be along the major axis of the bolt. Radial loads will likely snap a grade eight fastener. Grade eight bolts will shear unexpectedly, leaving you far worse off than nothing. For bumpers, winches, recovery points, use grade five bolts and regularly inspect them. Grade five bolts will gracefully stretch long before they shear, giving you ample opportunity to avoid a bad accident. The actual strength difference isn't that great. FWIW, I used to use all grade eight hardware until a PE friend explained the difference.
Oh yeah, I have seen stock brush bars do terrible damage to bonnets when used for recovery points. Go to the frame for your recovery points.
Paul |
JB
| | Posted on Tuesday, August 13, 2002 - 12:03 pm: |
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Lawrence- let me clarify and apologize for generalizing things with such a grand pronouncement with no explanation and for being totally wrong... I have never seen the one front recovery ring you refer to in action. I immediately jumped to the conclusion you were refering to those worthless 'tie-down' points on my range rover. I snapped one on my first recovery in my rover - almost injuring the man and son who were nice enough to stop and help me. After that and seeing a few other botched recoveries I am a safety freak. I think most people who see it go wrong get that way quick... |
Rob Davison (Pokerob)
| | Posted on Tuesday, August 13, 2002 - 12:19 pm: |
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yeah,, i am going to have raise BS flag on that whole grade 5 vs 8 thing. my gut is telling me that ain't quite right. i'll be back with proof in a little while.
rd |
John Kruger (Johnnyk)
| | Posted on Tuesday, August 13, 2002 - 01:44 pm: |
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The grade 8 vs 5 post is quite accurate. I had thought the same thing, but I do not work with this product line, so I verified this with a few people in our product department.(fasteners are our main product line)
A floor mat is a quick item to toss over any cable or strap, and it can assist in absorbing the load if a failure occurs.
John
www.teampb.com |
Dee
| | Posted on Tuesday, August 13, 2002 - 02:16 pm: |
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In one of the Jeep Rag's there is a new product a Winch Mat. Its made from nylon and it lays over the cable, prior too use you fill the bag with sand. It's supposed to take the bounce out of the line and dampen the snap if something breaks |
Moe (Moe)
| | Posted on Tuesday, August 13, 2002 - 02:31 pm: |
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Yeah there's something fishy about the grade 8 vs 5 claim. I understand the 8 is more brittle but it will fail at a higher rate. Is that what really matters? |
Chad
| | Posted on Tuesday, August 13, 2002 - 03:11 pm: |
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So Team Peanut Butter sells fasteners now? |
John Kruger (Johnnyk)
| | Posted on Tuesday, August 13, 2002 - 03:21 pm: |
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Fasteners is my day job....
John
www.teampb.com |
Chad
| | Posted on Tuesday, August 13, 2002 - 04:46 pm: |
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Don't quit your day job. |
Blue (Bluegill)
| | Posted on Tuesday, August 13, 2002 - 08:28 pm: |
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damn |
John Kruger (Johnnyk)
| | Posted on Wednesday, August 14, 2002 - 09:39 am: |
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Chad,
Do you know something I don't? Maybe you can enlighten me?
John
www.teampb.com |
brian kluge
| | Posted on Wednesday, August 14, 2002 - 09:49 am: |
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here's a pic of what happened last weekend that John was describing above...
Bri |
brian kluge
| | Posted on Wednesday, August 14, 2002 - 10:03 am: |
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and again...
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brian Kluge
| | Posted on Wednesday, August 14, 2002 - 10:07 am: |
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ah never mind - - what a pain in the ass...
The file you attempted to upload is larger than the maximum size for a file as specified by the
board administrator. File size is limited to -1 kilobytes. Your file was 1 kilobytes.
makes perfect sense to me,
bri |
Robbie (Robbie)
| | Posted on Wednesday, August 14, 2002 - 10:11 am: |
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brian, you have to be logged in as a registered user. go to utilities at left and edit profile... |
Paul T. Schram (Paulschram)
| | Posted on Wednesday, August 14, 2002 - 10:16 am: |
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At a former employer's facility, an electric winch was used to open boxcar doors. Shortly after my taking another rope rescue course, where I was taught how to use winches and the dangers of winches, I went back to the plant and demanded that those operating the winch were not to stand in the area where the cable could snap back and hit them. Wouldn't you know, my girlfriend at the time was running the winch when the cable snapped. It nearly removed the boxcar door and tore a huge chunk out of the side of the building. At my direction, she was standing inside the building when it happened. She was unscathed. Love those remote controls, they're not just for TV anymore.
About a week later at one of the mines the company owned, a winch cable snapped and beheaded one man and removed the arm of another. The week after this happened, a fellow got caught in a capstan winch and lost an arm and the hand from the other arm.
How many safety meetings do you think we had to attend where winches were the main topic of discussion?
Slow moving machinery is far more dangerous as a result of folks thinking it isn't as dangerous due to the slow speed. "I can get my hand out of there in plenty of time-oops, what hand?"
As for the grade eight versus grade five debate, better engineers than I told me this and I haven't had anybody disagree that could back it up (that wasn't meant to sound as inflammatory as it does!). Interestingly enough, some bolts that one would expect to be very strong are in fact, very flexible due to the heavy shock loading expected-a good example, light aircraft landing gear retaining bolts. The landing gear bolts on Piper J-3s are so soft, they will bend into the shape of a Z upon hard landings, but, they don't break. Of course, these same aircraft use bungie cords for shock absorbers! Some aircraft fasteners (JAN spec) have incredible elongation-before-failure specifications. Don't get me wrong, I think grade eight bolts would be great for doing such things as attaching shock absorber mounting hardware to frame rails where the mounting plates are intimately connected to the frame and unlikely to experience any shocks that would lead to shearing of the bolts. Same thing for body mounting hardware.
Just as we should pick the material we put on our hardware (loc-tite, anti-seize, oil, etc.) we should match the hardware to the application. I really see very few situations where one would use anything other than grade five or grade eight hardware on a Rover. I've been wrong before and will assuredly be wrong in the future. If I'm wrong here, I'll stop disseminating incorrect information-then again, it is the internet:-) Your mileage may vary, use only under close adult supervision, assembly required, no liability assumed or implied... |
brian kluge (Briankluge)
| | Posted on Wednesday, August 14, 2002 - 05:48 pm: |
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ok, i've given in to the crazy rules...
this is what a windshield looks like when a recovery strap goes through it...
 |
Rob Davison (Pokerob)
| | Posted on Wednesday, August 14, 2002 - 06:08 pm: |
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i have yet to be borded enough to prove you wrong, not that i know you are wrong, it's just my gut feeling telling me that in this application ,the something else will break before you have to worry about the difference between grade 8 and grade 5
actually my whole point was i was hoping someone would step up and be accountalbe and say, "i did a study of this and this is what i found" because we are all just spewing hearsay, including myself. only it's me thats telling me that something deosnt make sence. in theory i can agree, but in the practical world i dont know.
rd |
Blue (Bluegill)
| | Posted on Wednesday, August 14, 2002 - 06:19 pm: |
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so, what's the consensus on using stainless steel (approximately grade 4 to 5) hardware for recovery points? say four half-inch SS bolts to secure a recovery ring to a steel bumper? |
Rob Davison (Pokerob)
| | Posted on Wednesday, August 14, 2002 - 06:27 pm: |
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my point is if you used a 3" dia bolt that was super hardened grade 23 shit, i think it might be ok, because its so goddamn big.
SS is where it's at blue
rd |
Blue (Bluegill)
| | Posted on Wednesday, August 14, 2002 - 07:08 pm: |
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well, will that grade 5 SS elongate as opposed to catastrophically fail under load?
Damn, I knew I should have signed up for that materials testing course that my roomate took in grad school. This could be the only time I regret being a slacker... |
Jeff Price
| | Posted on Thursday, August 15, 2002 - 10:47 am: |
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Well OK. Now you made me go and blow the dust off the old "Standard Handbook of Fastening and Joining" and Shigley. Both Grades 5 and 8 are medium carbon steel, quenched and tempered. In grade 7 the threads are roll formed after heat treatment and I would figure that they are cold formed in Grade 8 as well. That would give you superior thread strength, due to the grain structure and would not in fact make the fasteners noticeably more brittle.
What we haven't really discussed is that there are two ways to load up a bolted joint with the load perpendicular to the axis of the fastener (in shear). The desired configuration is for the fastener to be preloaded such that all the shear load is carried by the friction between the two mating surfaces and not by the fastener at all. This gives you something along the lines of: the shear load needs to be less than the preload in the fastener times the coefficient of friction between the two mating surfaces times the surface area of the mating surfaces. In our case the load is the recovery pull, the coefficient of friction is that for steel to steel (Well it is painted but steel to steel is probably a good starting point), and the surface area is the area of contact surface between the mounting plate and chassis. Since there are multiple fasteners you divide the load over the whole set. I would assume an off-center loading with the whole load borne by one side of the bar.
Based on measurements from the factory brush bar setup on my 1997 Model year NAS Spec Discovery, the contact area of the brush bar with the crush can mount is 2 X 4, for 8 sq in. The bolts are 2.5 in apart and the pull ring center is 5.5 in from the centroid of the bolt hole group. Let's estimate the coefficient of friction as .3. The fasteners are 5/16 Fine Thread. I did not pull these to check, but they look like UNF and I am using the tables for UNF. The clamp load (75% of proof load) for grade 5 fasteners and lock nut is 5600 pounds, and for grade 8 is 7900 pounds.
so the primary shear for a grade 5 setup should be 8 * .3 * 5600 = 13,440 pounds
The primary shear for the Grade 8 setup is
8 * .3 * 7900 = 18,960
If you can get the joint to this level of preload then the grade 8 looks like the way to go. Still probably better to drill it out and put 1/2 in fasteners in.
The other way to load the joint is for the joint to be loose and have the fasteners carry the load. In our case, Since the pull does not go through the center of the bolt hole pattern, there is a secondary shear force induced by the reaction moment forces. Let us assume that we have an 8000lb winch hooked to the eye on the brush bar at max pull, and that the pull is parallel to the ground. We will see 4000 lb reactions in the other direction combined with reaction moments of 17,600 lb. In the case of the lower bolt the two forces are nearly coincident ( I cannot get in there and measure the angle right now and we are assuming the angle of force application anyway) so the total force on that bolt is ~21,600 lb with a sectional area of .0580 sq in (across the threads)we get a shear stress on the bolt of 372,413 psi. Across the body we get an area of .0767 for an shear stress of 281,620 psi. In any case the joint fails.
Solving for the F(worst) force in the worst case bolt when force F is applied then is:
F(worst)= F / 2 + (5.5 * F)/(2 * 1.25)
F(worst = F * (1/2 + 5.5/2.5) =F * 2.7
Using a conservative shear strength of 21.6 kpsi and the area of the .0767 the max value for F(worst) is 1656.72 and the max safe value for F is 613 pounds. If you could get a good centered pull across pull eyes then maybe 1200 pounds.
As far as stainless is concerned it can be soft and some alloys relax under prolonged tension show they can be difficult to get a preload on. So be sure of the properties of the alloy you are using. Unless you are using a precipitation hardened stainless like 17-4PH you are probably not going approach the kind of strength you can get with carbon steel alloys.
Note that I have not looked at the possibility of the bar failing and tearing out. I consider it an unlikely case with the fasteners we analyzed here. If you were to install larger fasteners you would want to look at that as well as what we did here.
Sorry to run so long
cheers
-jeff |
Todd Sanders (Sanderskog)
| | Posted on Thursday, August 15, 2002 - 11:03 am: |
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Now my head is 
I love this damn board.
Todd |
Blue (Bluegill)
| | Posted on Thursday, August 15, 2002 - 11:51 am: |
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Very interesting reading Jeff. Looks like recovering off of stock brush bar rings with inadequate hardware is cutting it close, but of course improved with grade 8 hardware. This agrees with consensus that stock brushbar ring recovery is a risky op, but risk is substantially reduced by upgrading to grade 8 hardware and KEEPING THOSE BOLTS TIGHT!
But what about a recovery ring mounted directly to the front of a steel bumper with 4 x 1/2" diameter SS bolts spaced at corners of a 4" square (base of recov ring is a 4" square)? Disregard steel bumper failure and recovery ring failure as a variable. The supplier of the SS bolts in question has rated them at "just below grade 5". What kind of straight pull load can those 4 bolts withstand? (Of course varying degrees of side pull will induce increasing shear stresses that would have to be taken into consideration.) |
John Lee
| | Posted on Thursday, August 15, 2002 - 12:03 pm: |
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Jeff, great post. Very informative and well written. Now I definitely know whom to ask when I have a fastener question. |
Ross Thoma
| | Posted on Thursday, August 15, 2002 - 06:08 pm: |
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Hey Todd
I am from the great white north and I was taught and always did put some sort of fabric (usualy my extra winter coat) over the center of the cable.
Never had or seen one go but I thought that an ounce of prevention.... glad it worked for you.
Ps I have a new 2003 disco "two weeks old" and find it hard to get out of Chicago to go off roading.
Ross Thoma |
Jeff Price
| | Posted on Friday, August 16, 2002 - 11:43 pm: |
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Yeah Blue, keeping the bolts tight is key, because if the bolts are tight they are only loaded in tension and the shear gets distributed across the entire surface of the joint. If the bolts are loose they are carrying the load themselves and you are relying solely on the strength of the fasteners.
Assuming a pull straight from the face, the recovery hook with four bolts is really a tensile load on the bolts since the pulling force acts throught the centroid of the bolt pattern. If you are pulling at some some angle very far from perpendicular then you will have an uneven distribution of load in the bolts but won't have a significant shear load until you get close (say within 30 degrees) of parallel to the face.
It is hard to say the strength of those stainless bolts. Does the manufacturere list the steel used or proof strength? I have to admit to being a little hesitant to guess because some stainless alloys are so soft and/or have fatigue properties similar to aluminum. Regular carbon steel alloys stretch linearly to their limit and fail, while softer alloys start to deform plastically at a lower percentage of their limit, which makes it hard to say what is a safe load. That said, lets run some numbers. The proof on a grade 5 bolt is 85 kpsi. If we go with 75kpsi as "almost" grade 5, then each bolt should be able to withstand 14726 lb. I would not exceed 75% of that so we get 11,044 lb per bolt. Depending on what the exact strength is and the exact behavior of that alloy under load.
So in a straight pull it seems like you should have plenty of safety factor. 40,000 / 8,000 = 5. If you get off-axis then you would have to evaluate each case.
When I worked in a DoD facility the lifting equipment had a factor of safety of 5, so your numbers seem about right. I would just double check the rating on the fasteners.
-jeff |
Rob Davison (Pokerob)
| | Posted on Saturday, August 17, 2002 - 11:43 am: |
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also , what are you using to pull the recovery attatchment? chances are the little pin holding the hook is the weak link in this equation.
rd |
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