Hitch mounting / Leverage Question

zstroken said:
All is true John, but if you can must move your hitch forward, get rid of a lot of the flex versus boxing in the whole back end of the frame. Which solution weighs less? Which solution puts more weight behind the rear axle instead of infront of it? I know I moved my hitch forward to get it closer to the axle and I think I used about 2 lbs of steel to reinforce the hitch for the extra leverage I put on my moving my slide in hitch out further.
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I see what your saying Dan. You can beef the receiver but what about the insert? So you beef your hitch and slide it back. Now your hitch insert is longer. It does not flex? I know mine is tweeked and it only stuck out 4" from the receiver. It is bent a good 1/4". I bet it had to bend a good deal further than 1/4" to end up that way. I think I bent it an Cynthiana. When I killed my traction bars. You might remeber seeing this.:hehe:

To me it just seems the better plan to make my hitch insert as short as possible by leaving the receiver in place and boxing the frame. IMHO that sounds more rigid. I would only slide the receiver forward to shorten my overall hitch length. Which I have done. But I would not move it any further forward then needed. I could move it further forward but my insert would get longer. Sure my frame would flex less but would my hitch and receiver flex more? I sure think so.
 

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Hitch

I think a lot of drag tricks work on a pulling truck. Pinion angles, Instant center, 4 wheel weights(that has been done by the way). I like these kind of treads I always learn and that's always a good thing.
 
Glad I could get some of you guys thinking! Thanks for the input guys!
 
JOHNBOY said:
I see what your saying Dan. You can beef the receiver but what about the insert? So you beef your hitch and slide it back. Now your hitch insert is longer. It does not flex? I know mine is tweeked and it only stuck out 4" from the receiver. It is bent a good 1/4". I bet it had to bend a good deal further than 1/4" to end up that way. I think I bent it an Cynthiana. When I killed my traction bars. You might remeber seeing this.:hehe:

To me it just seems the better plan to make my hitch insert as short as possible by leaving the receiver in place and boxing the frame. IMHO that sounds more rigid. I would only slide the receiver forward to shorten my overall hitch length. Which I have done. But I would not move it any further forward then needed. I could move it further forward but my insert would get longer. Sure my frame would flex less but would my hitch and receiver flex more? I sure think so.
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I agree John, I ended up sliding my hitch receiver pretty far forward since I needed to do it to get the hitch point as close as possible. WHen sliding it forward I found some holes already there so that is the scientific method I used to determine how far to go forward. I actually ended up having to slide the hitch itself out about 4 inches or so. I was worried about the reciever handling the added stress so what I did was take some 3/4" angle probably 1/8" maybe 3/16" thick, cut them about 20" long and go from the area right behind the slide in hitch, and run them up to the top of forwardmost top point of the hitch right up by the frame. I have had zero issues with the hitch, but it is probably cause I last time my truck was on the dyno it was only about 450HP too. You big power guys might be able to break something.


Mat keep the simple explanations coming. Along the same lines if I hung my weights forward or backwards, would it not make a difference as long as the center of gravity of the weights was in the same spot??
 
CSM diesel said:
What kind of calculations are we talking about here? To accurately model the average sled pull would take horrendous amounts of non-linear mathematics. Moving the "hook point" would provide more benefit than moving the hitch attachment point as far as moving the forces and moments around the rear axle.
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I agree on the moving the hook point forward. I was talking about neglecting frame flex, etc. I don't even want to try to model events during the sled pull. Lets just stay with statics for now!
 
zstroken said:
I agree John, I ended up sliding my hitch receiver pretty far forward since I needed to do it to get the hitch point as close as possible. WHen sliding it forward I found some holes already there so that is the scientific method I used to determine how far to go forward. I actually ended up having to slide the hitch itself out about 4 inches or so. I was worried about the reciever handling the added stress so what I did was take some 3/4" angle probably 1/8" maybe 3/16" thick, cut them about 20" long and go from the area right behind the slide in hitch, and run them up to the top of forwardmost top point of the hitch right up by the frame. I have had zero issues with the hitch, but it is probably cause I last time my truck was on the dyno it was only about 450HP too. You big power guys might be able to break something. Zing!:hehe: Dan I am pretty sure you made a little more HP than me. Just a little
Mat keep the simple explanations coming. Along the same lines if I hung my weights forward or backwards, would it not make a difference as long as the center of gravity of the weights was in the same spot??
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I have wondered about the weight hanging thing also. Sounds like the best way to answer these questions would be with scales.
 
John I have the dyno sheet somewhere and it showed 468 I think.

I do think the DMAX trucks have stouter frames, they just don't appear to bow in the center like the 2nd gen dodges do.
 
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I want to know how much adding helium to my rear tires will help with my weight????
 
FYI my hitch insert is solid 2" stock. I don't think I will bend it. There are lots of ways to do it. Mine ended up the way it is cause of 1. it was what I had, 2. it was easiest way to do it, 3. I think it will get the job done.

Off topic are we gonna see the truck pullin in 08??
 
zstroken said:
FYI my hitch insert is solid 2" stock. I don't think I will bend it. There are lots of ways to do it. Mine ended up the way it is cause of 1. it was what I had, 2. it was easiest way to do it, 3. I think it will get the job done.

Off topic are we gonna see the truck pullin in 08??
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If I can bend one anyone can.
 
johnboy said:
Mat keep the simple explanations coming. Along the same lines if I hung my weights forward or backwards, would it not make a difference as long as the center of gravity of the weights was in the same spot??
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John, the answer is easy if you had weights that are perfectly square - in which case the center of gravity (in fancy terms, first moment of inertia) is the same no matter which way you hang 'em.

If you want to get real nitpicky, you could look at an IH suitcase weight, and just from the shape, you can see that with the hanging notch in the back and the shape on the bottom, the CG is probably more forward if you put them on as normal. But putting them backwards is probably only slightly less effective.

Suitcase weights with pointy fronts on them might be better backwards if you're building right to the 60" limit. This is why some guys go for the gusto and hang 'em sideways. I'm not saying that's the best way to set the truck up, but if you want to maximize front downforce, that's the solution.

And BTW on the hitch sections - I went 2.5" solid and so far it seems bulletproof. FWIW, 2.5" is more than 2X as stiff as 2" - and as such, the stresses are more than halved. Food for thought!

"2 inch is 2 small" LOL
 
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I'm glad I'm not the only one that drew out a free body diagram prior to modifying/moving my receiver for pulling... I was starting to think I was a little weird.

If you assume everything is rigid (no major flexing), the only thing that matters is the hooking point in relation to the rear axle.$.02
 
GOT-Torque said:
I'm glad I'm not the only one that drew out a free body diagram prior to modifying/moving my receiver for pulling... I was starting to think I was a little weird.

If you assume everything is rigid (no major flexing), the only thing that matters is the hooking point in relation to the rear axle.$.02
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I think though that the dodge frame on the second gens especially the 94/95's flex, especially watch a 94/95 bow in the middle, that has to sacrifice hitch height.
 
this book doesn't have enough pictures for those of riding the short buss:nopics:
 
GOT-Torque said:
If you assume everything is rigid (no major flexing), the only thing that matters is the hooking point in relation to the rear axle.$.02
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My thoughts exactly.
 
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