2500HDee
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Re: WDH and airbag setup Question
Ron, you are right. Thank you for the correction. It was the center of gravity's distance from the fulcrum that I was thinking of as you pointed out in the wheelbarrow post. I am going to delete my other posts as if to not leave incorrect information posted. I am going to run some numbers on the COG of the truck and load in the bed though, as I do think that it is significant in the weight distribution of the truck. I am referencing a specific time that a kid I was roofing with loaded an entire pallet of shingles in an F150 and the front suspension was at full droop. And yes, he did have them loaded over the axle, not behind it. Also, when setting up race cars we used 4 wheel scales and adjusted the coil overs up or down to balance the load side to side and or front to rear but I realize I am providing personal examples here and not numbers so I will get back with everyone soon. Thanks for the discussion. I just remembered, you can only do this for cross-corner weights, not for side to side or front to rear. So disregard that.439Views0likes0CommentsRe: WDH and airbag setup Question
Ron Gratz wrote: Let's say the length of your beam is "WB". Since it's a uniform beam, the distance from the front axle to the CG is WB/2 and the distance from the CG to rear axle is WB/2. With the beam at an angle, "theta", the horizontal distances from front axle to CG and from CG to rear axle are cosine(theta)*WB/2. To maintain rotational equilibrium, the sum of the moments about any point must equal zero. For your example below, the 25# force at the front generates a CW moment equal to 25*cosine(45 degrees)*WB/2. The 75# force at the rear generates a CW moment equal to 75*cosine(45 degrees)*WB/2. Clearly, your free body cannot be in rotational equilibrium unless the upward force at the front and the upward force at the rear are equal. The end reactions shown in the diagram below must both be equal to 50#. In general the sum of moments about the CG must give: Ff*cosine(theta)*D1 - Fr*cosine(theta)*D2 = 0 where Ff and Fr are the vertical upward forces acting at front and rear, D1 is distance from front axle to GC, and D2 is distance from CG to rear axle. Therefore, we have: Ff*D1 = Fr*D2 And we know: Ff+Fr = W = weight of beam These two equations give: Ff = W*D2/(D1+D2) and Fr = W*D1/(D1+D2) The distribution of weight is not dependent on the value of "theta". When you stand the beam vertically on end, as you did in your first diagram, the front reaction force, the rear reaction force, and the weight force are all collinear. The values of D1, D2, and D1+D2 are all zero. There are no moments acting about the CG. You have a case of unstable equilibrium. Ff and Fr could be any value as long as their sum is equal to the weight. However, in the limiting process of approaching 90 degree slope, we know that the above equations for Ff and Fr apply. Ron Following diagram provided by 2500HDee Ron, you are right. Thank you for the correction. It was the center of gravity's distance from the fulcrum that I was thinking of as you pointed out in the wheelbarrow post. I am going to delete my other posts as if to not leave incorrect information posted. I am going to run some numbers on the COG of the truck and load in the bed though, as I do think that it is significant in the weight distribution of the truck. I am referencing a specific time that a kid I was roofing with loaded an entire pallet of shingles in an F150 and the front suspension was at full droop. And yes, he did have them loaded over the axle, not behind it. Also, when setting up race cars we used 4 wheel scales and adjusted the coil overs up or down to balance the load side to side and or front to rear but I realize I am providing personal examples here and not numbers so I will get back with everyone soon. Thanks for the discussion.440Views0likes0CommentsRe: WDH and airbag setup Question
Ron Gratz wrote: 2500HDee wrote: Both the WDH and airbags/stiffer leafs/add-a-leafs/Timbrens/etc will affect the weight on the front axle. The difference is the rear suspension will change this regardless of whether a trailer is attached or not. Ever seen that guy with a whole pallet of shingles in his F-150? The front tires almost come off the ground on every bump. Since he can't use a WDH to transfer the weight to the front axle of his truck full of shingles, the other option, assuming it would not exceed the RAWR or GVWR of his truck, is to have stiffer rear springs. By bringing the back of the truck back up it will restore weight to the front axle and make the truck safe to drive. This can be illustrated with a simple free body diagram.--- Can you post (or describe with words) a simple free body diagram which will show how using air bars to bring the back of the truck up will restore load to the front axle? Also, can you provide an estimate of how much load is removed from the front axle for a given weight of shingles, and how much load is restored to the front axle by raising the rear with air bags? Finally, do you have any scales measurements to substantiate this claim? Ron Sure thing, I will get back to you after work tonight.439Views0likes0CommentsRe: WDH and airbag setup Question
These discussions seem to be endless in forums across the internet. The weight distributing hitch is to restore the weight to the steer axle and put some of the tongue weight on the trailer axles. The height of the rear of the tow vehicle does not matter and you can air up before or after you hook up your WDH but make sure you end up with the front at or slightly higher than the measured height before you connected the trailer. Both the WDH and airbags/stiffer leafs/add-a-leafs/Timbrens/etc will affect the weight on the front axle. The difference is the rear suspension will change this regardless of whether a trailer is attached or not. Ever seen that guy with a whole pallet of shingles in his F-150? The front tires almost come off the ground on every bump. Since he can't use a WDH to transfer the weight to the front axle of his truck full of shingles, the other option, assuming it would not exceed the RAWR or GVWR of his truck, is to have stiffer rear springs. By bringing the back of the truck back up it will restore weight to the front axle and make the truck safe to drive. This can be illustrated with a simple free body diagram. This can be done the same way with a trailer on. The easiest method is to: 1. Measure front ride height. 2. Connect trailer. 3. Adjust air bags. 4. Measure front ride height. 5. Adjust WDH to achieve front ride height at or slightly above step 1. If you add too much air in step 3 then you won't be able to add any tension to the spring bars without bringing your front ride height below the initial level and therefore cannot transfer any weight to your trailer axles. If the front is at or slightly (1/2" to an 1") above the initial value and IF the rear axle, tires, hitch, and payload of the truck can handle this amount of tongue weight, you don't even need a WDH. (This was the case with my last truck without even needing air bags.) If not, you need to let out some air so that you can actually use the WDH. This is about distributing the weight to the axles of the truck and trailer and is simple statics. This is not rocket science. Requirements: Front axle of truck -> should have the same or slightly less weight (height) than unloaded. Rear axle of truck -> do not exceed RAWR (height does not matter) Both axles of truck combined -> do not exceed GVWR Hitch -> do not exceed weight rating (either with or without WDH, there are separate ratings) Trailer axles -> do not exceed GVWR Entire rig -> do not exceed GCVWR How you arrive at the weights on each axle does not actually matter, only that you use what you have (WDH, airbags, self leveling suspension, unicorn farts) to keep the axle weights within these guidelines.439Views0likes0CommentsRe: Just Suspension Recommendations - No Legal Weight Advice
I have had air bags in the past and now have Timbrens (not for our TT but for hauling loads in the bed) and I like the Timbrens because there is no adjustment needed. They did come with a 1" spacer to move them into position so that they are always engaged if you are always carrying a load like a TC or a utility body. The only downside is that as noted above, the axle hits the Timbrens before the overload springs and causes somewhat harsh transitions to the overload springs when carrying a load that is not quite heavy enough to sit on them all the time. I do like the improved handling though. Even with 2000 - 3000 lbs in the bed there is little body roll in corners and the steering stays crisp since the truck is not squatting and allowing weight to be transferred to the rear. Airbags are nice because they provide the same benefit but are adjustable although they can leak and require you to set them to the desire pressure for the current load to get optimal results.212Views0likes0CommentsRe: External Speakers, do you really want them ?
I loved sitting under the awning next to the river this weekend during a rainstorm playing cards and listening to music quietly with my friends. There was no one else within earshot because I choose to camp in areas where people are not nearby. If I wanted to be around people I would choose differently as some others do and that is fine. But to say that there should be no external speakers is silly. Also to get all worked up about "noise pollution" when the original post is about water damage due to a leaking speaker is hilarious. Thanks OP for posting this, I never even thought about making sure the speakers were sealed properly. I have checked roof accessories and windows but not the speakers. Now they are on my list. This is why we have forums.186Views0likes0CommentsRe: 2014 Ultimate 1 Ton Challenge results
IdaD wrote: If you consider the loads these trucks were hauling and then apply the results of the entire test to the real world and how most people drive...take you're pick - performance wise you've pretty much got a tie. Subjectively people are going to like certain things or dislike certain things and decide which is their favorite, but in terms of towing performance, nobody rational is going to choose one over another because it goes 59 up a hill instead of 56, or it required two taps on the brakes instead of four with the exhaust brake engaged. Or that's my take anyway. This is spot on. People are always going to bench race or bench tow in this case on the internet but the reality is that there is no bad choice these days. I am actually amazed how even they are, they obviously benchmark the heck out of each other.157Views0likes0CommentsRe: Big SUV or truck
RedRocket204 wrote: SilverEscape wrote: I don't like the look of toppers, at all, LOL but even if I succumbed to one, still can't see me getting climbing in with heels and a skirt to get out the baby's bag for daycare. This is why I was considering the large SUV. Even though none of them are my style either. Just want to point out that even with two car seats in the back seat of a crew cab truck, there is still a lot of floor room for diaper bags, groceries, etc. where you would only need to put a stroller in the truck bed. Current trucks are a lot more family friendly than they used to be. We have both a crew cab truck w/ canopy and Sequoia and actually prefer to use the truck for family outings...although 2 kids and no car seats but additionally, two small dogs. We too have a crew cab with a topper and an SUV. We always use the truck for family trips as you can fit the whole family in the truck and tons of stuff in the bed. I also put a roof rack on so we can haul a space booster if we want. I have had SUVs, Vans, Trucks, and Cars and nothing tops the usefulness of the crew cab pickup for a family unless you need seating for 6+447Views0likes0Comments
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