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Old 01-27-2011, 12:52 AM   #1
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Re: Extreme Drops

my truck is a driver also (only on a trailer when its broken) love cruising around as low as i can in my truck... drove it to midwest all truck nats from stl to kc and back and i think it rides better on air then it did from the factory
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Old 01-31-2011, 08:09 PM   #2
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Re: Extreme Drops

can you explain why there would be a problem with vibrations with the driveshaft on an incline since the vibrations are caused from the angles of the ujoints working aginst eachother? or is that not correct?
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Old 01-31-2011, 11:16 PM   #3
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Re: Extreme Drops

can you explain why there would be a problem with vibrations with the driveshaft on an incline since the vibrations are caused from the angles of the ujoints working aginst eachother? or is that not correct?
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Old 02-01-2011, 12:41 AM   #4
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Re: Extreme Drops

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Originally Posted by bedsled71 View Post
can you explain why there would be a problem with vibrations with the driveshaft on an incline since the vibrations are caused from the angles of the ujoints working aginst eachother? or is that not correct?
Driveline vibrations can be caused by several different factors. From what I've learned: the operating angles are the primary culprit; then phasing, & then "secondary couple loads".

Secondary couple loads brief explanation from Greg Frick @ IEDLS: These loads operate at 90 degrees to the shaft. With equal and opposite angles these loads cancel out and are not an issue. When the angles are equal, but both on the same side of the drive shaft (the top in my case), they add up. The result of additive secondary couple loads is a shaking of the mounts: the transmission and the rear end. This shaking goes everywhere in the car and is very aggravating.

An odd feature of the secondary couple load problem is that the farther they are apart the less of a problem they seem to be. Unfortunately there is no rule on how far is far enough or how close is too close. What works in a '53 Studebaker will not work in a bucket T.


I have asked more than once for an explanation on the inclined driveshaft issue but haven't gotten any solid feedback. IEDLS has reference material that only states that is the one orientation to avoid. As far as I can tell, the main reason is because that configuration yields excessive working angles for the u-joints. Pages 3-4 explain some typical variations on driveline set-ups:
http://www.iedls.com/asp/admin/getFi...&TID=28&FN=PDF
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Building a small, high rpm engine with the perfect bore, stroke and rod ratio is very impressive.
It's like a highly skilled Morrocan sword fighter with a Damascus Steel Scimitar.....

Cubic inches is like Indiana Jones with a cheap pistol.

Last edited by SCOTI; 02-01-2011 at 12:42 AM.
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Old 02-01-2011, 01:43 AM   #5
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Re: Extreme Drops

One thing we must all remember when dealing with "customized" and "altered" trucks, chassis, suspension, drive-trains, etc. is that there is no longer a perfect world scenario. If we were to drive vehicles that were set up according to spec. in its "perfect" form... they would no longer be appealing to us.

Once we have voided our factory warranty by modifying our ride, we must look at our game plan from a different angle (pun intended). We must find the compromise, that allows us to accomplish the MOST of what we want (sometimes we get lucky and accomplish ALL of what we want, but this is not always the case). This may mean that we get conflicting or unclear information from different sources... even professionals. Heck, I could go and see three different doctors for the same illness and be prescribed three seperate remedies! This is just how it goes. And why is it that whenever I call and talk to a wheel manufacturer that they can never tell me the backspacing I need... don't they make wheels and sell them everyday? Oh, they just don't want to be liable and responsible if it doesn't work out and the customer isn't satisfied.

Scoti- In your case, your driveline will always slope up in the rear... it's just going to be that way unless you raise your truck another 4"-6". So, what can be done? One real world solution I have recommended and used is a CV or Double Cardon Joint. This will allow the angles to cancel eachother out... no vibrations. I know your drive-line guys told you that's just a band-aid fix... but what other alternatives are there at this point? Maybe raise the truck? (Please don't take this wrong, as we are friends and we talk frequently discussing all sorts of truck related items... I am just using this scenario as an example).
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Old 02-01-2011, 10:35 AM   #6
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Re: Extreme Drops

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Originally Posted by porterbuilt View Post
One thing we must all remember when dealing with "customized" and "altered" trucks, chassis, suspension, drive-trains, etc. is that there is no longer a perfect world scenario. If we were to drive vehicles that were set up according to spec. in its "perfect" form... they would no longer be appealing to us.

Once we have voided our factory warranty by modifying our ride, we must look at our game plan from a different angle (pun intended). We must find the compromise, that allows us to accomplish the MOST of what we want (sometimes we get lucky and accomplish ALL of what we want, but this is not always the case). This may mean that we get conflicting or unclear information from different sources... even professionals. Heck, I could go and see three different doctors for the same illness and be prescribed three seperate remedies! This is just how it goes. And why is it that whenever I call and talk to a wheel manufacturer that they can never tell me the backspacing I need... don't they make wheels and sell them everyday? Oh, they just don't want to be liable and responsible if it doesn't work out and the customer isn't satisfied.

Scoti- In your case, your driveline will always slope up in the rear... it's just going to be that way unless you raise your truck another 4"-6". So, what can be done? One real world solution I have recommended and used is a CV or Double Cardon Joint. This will allow the angles to cancel eachother out... no vibrations. I know your drive-line guys told you that's just a band-aid fix... but what other alternatives are there at this point? Maybe raise the truck? (Please don't take this wrong, as we are friends and we talk frequently discussing all sorts of truck related items... I am just using this scenario as an example).

As I mentioned, I'm confident in your recommendation per our discussions. I also wanted a 'fudge' factor built-in so I have the ability (if possible) to adjust the angles just in case.

I currently have it set-up w/2.5° @ the trans & 2.2~2.4° down @ the pinion w/the d.shaft slightly sloping down. I haven't gotten over to the truck to measure & see how much material out of the floor this would require removing. This would be my alternative if the numbers we discussed (3° down @ tailshaft, CV @ trans, & as close to 0° @ the pinion as possible) doesn't work.
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Building a small, high rpm engine with the perfect bore, stroke and rod ratio is very impressive.
It's like a highly skilled Morrocan sword fighter with a Damascus Steel Scimitar.....

Cubic inches is like Indiana Jones with a cheap pistol.

Last edited by SCOTI; 02-01-2011 at 10:36 AM.
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Old 02-03-2011, 10:50 PM   #7
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Re: Extreme Drops

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Originally Posted by bedsled71 View Post
can you explain why there would be a problem with vibrations with the driveshaft on an incline since the vibrations are caused from the angles of the ujoints working aginst eachother? or is that not correct?
This should explain it.

http://www.hotrodhotline.com/md/html..._harmonics.php
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Old 02-03-2011, 11:51 PM   #8
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Re: Extreme Drops

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This should explain it.

http://www.hotrodhotline.com/md/html..._harmonics.php
Posted via Mobile Device
Actually, that only explains the equal but opposite need for the cancellation of the angles to eliminate the possibility of vibrations (it also states the d.shaft should be sloping down approx 1°).

My buddy also questioned how the d.shaft knows whether it's sloping up or down thus it shouldn't make a difference.

This is why I stated earlier that the 'difference' would be that when the shaft slopes upward to the pinion, you calculate the angles differently. The result is typically excessive angles that are nearly impossible to cancel thus why I feel they recommend it to be avoided.
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Building a small, high rpm engine with the perfect bore, stroke and rod ratio is very impressive.
It's like a highly skilled Morrocan sword fighter with a Damascus Steel Scimitar.....

Cubic inches is like Indiana Jones with a cheap pistol.
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Old 02-04-2011, 09:14 AM   #9
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Re: Extreme Drops

Hey Scoti how far from Dallas to Columbus....y'all only have about six months!
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Old 02-04-2011, 10:11 AM   #10
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Re: Extreme Drops

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Hey Scoti how far from Dallas to Columbus....y'all only have about six months!
17hrs straight through..... been there & done it so I know what to expect. This truck will make that drive.
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Building a small, high rpm engine with the perfect bore, stroke and rod ratio is very impressive.
It's like a highly skilled Morrocan sword fighter with a Damascus Steel Scimitar.....

Cubic inches is like Indiana Jones with a cheap pistol.
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Old 02-04-2011, 09:51 AM   #11
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Re: Extreme Drops

Quote:
Originally Posted by SCOTI View Post
Actually, that only explains the equal but opposite need for the cancellation of the angles to eliminate the possibility of vibrations (it also states the d.shaft should be sloping down approx 1°).

My buddy also questioned how the d.shaft knows whether it's sloping up or down thus it shouldn't make a difference.

This is why I stated earlier that the 'difference' would be that when the shaft slopes upward to the pinion, you calculate the angles differently. The result is typically excessive angles that are nearly impossible to cancel thus why I feel they recommend it to be avoided.
Then here is some more.....

http://www.drivetrain.com/parts_cata..._problems.html
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Old 02-04-2011, 10:28 AM   #12
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Re: Extreme Drops

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Originally Posted by 502ss View Post
Then here is some more.....

http://www.drivetrain.com/parts_cata..._problems.html
Posted via Mobile Device
Quoted from that source:
Quote:
When the slopes are in the Same direction on two connected components, Subtract the smaller number from the larger to find the u-joint operating angle. When the slopes are in the Opposite direction on two connected components, Add the measurements to find the u-joint operating angle.
This would mean if the trans is angled down & the d.shaft slopes up, you would add the angles to arrive @ the working angle of the joint. We'll say the trans is @ 3°dn & the shaft is 2° up: 3+2 = 5° working angle.

If the driveshaft is sloping down from the pinion & the pinion is angled down, you would subtract the angles. We'll say the d.shaft is @ that same 2° up & the pinion is 3°dn: 3-2 = 1° working angle.

The numbers yield a 4° difference.
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Building a small, high rpm engine with the perfect bore, stroke and rod ratio is very impressive.
It's like a highly skilled Morrocan sword fighter with a Damascus Steel Scimitar.....

Cubic inches is like Indiana Jones with a cheap pistol.
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Old 02-01-2011, 02:25 AM   #13
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Re: Extreme Drops

SCOTI -

I know this isn't a Chevy but the point still stands the same... I bought a Hardbody ('97) brand new with 3 miles on it. When it had only 794 it was in my garage on jack stands getting a static drop with the frame 2 1/4" off the ground, that's pretty low. Driveline was pointed up for sure! I put lots of trips on the truck around 700 miles or so with zero issues ever. Sold the truck with over 24k on it and the driveline nor u joints were ever replaced. And no the truck was not abused either, no dents, scratches, or stains. -The driveline angles might never be completely perfect but you can make it work. I think the driveline companies might be scaring you a little bit.

Like you said, do it right the first time and it will be just fine!
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Old 02-01-2011, 12:46 PM   #14
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Re: Extreme Drops

heavey metal that Justin Drove 2300 miles each way from Ventura, CA to Indianapolis, IN



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Old 02-01-2011, 01:26 PM   #15
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Re: Extreme Drops

Ok, I knew what vehicle you were talking about.
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Building a small, high rpm engine with the perfect bore, stroke and rod ratio is very impressive.
It's like a highly skilled Morrocan sword fighter with a Damascus Steel Scimitar.....

Cubic inches is like Indiana Jones with a cheap pistol.
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Old 02-01-2011, 01:43 PM   #16
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Re: Extreme Drops

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Ok, I knew what vehicle you were talking about.
many don't though so i threw up a few pics
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Old 02-01-2011, 02:42 PM   #17
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Re: Extreme Drops

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Ok, I knew what vehicle you were talking about.
That is so cool you knew that but we figured to show all people that do not know.You can drive a full blown show truck across country .
Justin
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Old 02-04-2011, 06:56 PM   #18
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Re: Extreme Drops

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heavey metal that Justin Drove 2300 miles each way from Ventura, CA to Indianapolis, IN


was that truck built on tv
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Old 02-04-2011, 07:41 PM   #19
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Re: Extreme Drops

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was that truck built on tv
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Yes it was built it in 90 days and took it to detroit then drove it to
Gm in detroit in the freezing ass cold weather.lol
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Old 02-03-2011, 04:00 PM   #20
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Re: Extreme Drops

What happen guys nobody wants to come out and play!
Justin
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Old 02-03-2011, 04:38 PM   #21
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Re: Extreme Drops

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What happen guys nobody wants to come out and play!
Justin
Yeah, I'm surprised this thread isn't a lot more active than it is.
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Old 02-03-2011, 04:42 PM   #22
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Re: Extreme Drops

It would be cool to see some "action" shots of Heavy Metal out on the Interstate! I think I remember hearing it even rained on you guys.
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Old 02-03-2011, 05:11 PM   #23
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Re: Extreme Drops

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It would be cool to see some "action" shots of Heavy Metal out on the Interstate! I think I remember hearing it even rained on you guys.
I remember seeing it in indy looked like a swiming pool and justin didnt care LOL interior was replaced i think 2-3 times due to un foreseen rain storms
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Old 02-04-2011, 10:56 AM   #24
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Re: Extreme Drops

ken, do you have any side shots of that truck so that the wheels can be better seen?
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Old 02-04-2011, 11:41 AM   #25
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Re: Extreme Drops

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ken, do you have any side shots of that truck so that the wheels can be better seen?
Lets see what I have...
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