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Noise from rear end.......the 14ff, Fixed!!! pg3

Leper

Leper

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Dallas Baby!!!!
I've got a noise on decel that I am having trouble finding. At any speed above 30 or so, if I let off of the gas, I hear a horrible noise. A gear meshing kind of noise. ERRRRrrr ErrrrEr Errrrrrrr(best i can describe it) It almost sounds like its coming from the trans or tcase. Lots of new parts: 5.38 gears( proper backlash), carrier, master install kit.
It is a noise I had before. It did it for a long while with the other gears(4.56) and the old carrier, just not as loud. It just went away one day after wheelin. when I pulled the cover off to do the gear swap, I had alot of water in the diff. I am thinking that the extra fluid helped contain the noise.

I just added an emergency brake cable to one side, but it is not hooked up yet. It is zip tied to the frame until I get the other one and put it on. That could have something to do with it. I had cut the old half of a cable out about the time the noise stopped. Mabey I'm grasping at straws there.

The axle has alot of angle in it. It pretty much points at the tcase. I wheel with others with the same angle and they have no problems. U joints are good. It is a 241 tcase with a SYE.

If I let off of the gas the noise starts. however, if I apply the brake, it will not make the noise until I let off of the brake. Usually I have one foot on the gas and 1 on the brake. It makes the noise if the truck in in neutral or drive.

Could the hub/axle bearings cause this?(Hope so) I haven't looked at them. Could it be in the tcase? I think the noise is being transmitted through the dshaft from the rearend. I actually swapped in a different tcase and the noise didn't change.(also used a different driveshaft at that time) So that leaves the rearend, or the transmission.
I am going to recheck the backlash, but because it has done this before, I don't think that will be it.

Please post up any suggestions. I am going to remove the ebrake cable tonight, just in case.

******MY FIX******
It is the angle that my Dshaft is at. I added the overload spring and a zero rate while I did the 5.38 swap and the extra speed of the Dshaft are making a "gear chatter" noise.
 
Last edited:
New info......
With the truck in neutral, I can grab the driveshaft and turn it almost a quarter turn. Do I have a locker problem?
 
If you have a detroit that much slack is normal. My gears were setup to around .009 backlash and with the detroit I could turn the shaft almost 1/4 turn. There was a post somewhere that explained how this was normal with a detroit.

Ira
 
My driveshaft turns almost a 1/4 turn too and I have a loc rite. I hate it, because I have a stick and if I'm not careful I can make things go bang!
 
Same here I have a detriot and i have lots of slop but no noise only clinging, tires squeeling and poping when i dump the clutch or try to take off to fast:D
 
My roommates truck has a detroit rear. I has a gear whine all the time and the ring and pinion is set up perfectly. I'm convinced its just the locker. He has all terrains, and there is very little road noise besides that faint gear whine.
 
The noise is not a whine at all. If you think sm465 that is about to explode, that is the noise.
Its not the u-joints, they are all new/semi new and all are free with no excessive play. The one at the rear diff is almost perfectly straight. The one at the tcase doesn't bind or act wierd in any way, and the axle and yoke do not make contact.

Chaddy.... The reason I went to a SYE is because I broke the ears off of my slipyoke wheeling once. So yes, the yoke at the tcase has come loose before. Why??? I don't think I'm going to like your answer.


And like I said before, this noise was there before and went away, now its back after rebuilding the rear.
To give you some idea of the noise, think about driving with an automatic and while you are moving,pop it in and out of Park.
 
Leper said:
To give you some idea of the noise, think about driving with an automatic and while you are moving,pop it in and out of Park.
Click to expand...

That is what my detroit would sound like when I was high centered and would spin the tires. Once I stepped on the brake one side locked and the other kept spinning it unloaded the detroit and made that clicking noise. Maybe your locker is stuck open.

But I see it only does it on a coast:thinking:

Ira
 
Make sure that both tires are very close to the same diameter. Same amount of wear, same inflation pressure. Otherwise the locker will unlock one side frequently.

Lots of locker theory here:
http://www.angelfire.com/super/ThunderTruck/Technical.htm

Click on the "Automotive Locking Differentials" link at the top of the page. It's a Microsoft Word doc, so you'll need a program that can open it.
 
i have a sound from my 14b with detroit as well. it sounds like its dry almost or grinding noise, i check the fluid and its full???? i had it set up professionally by a shop. i duno what the problem is
 
I had a F-150 one time that made a real bad grinding sound in the rear end and come to find out the pins that hold the brake shoes on had broke and let all the hardware come loose and get ground up.

If you have a detroit that much slack is normal
Click to expand...

Mine is the same way
 
I still think it's your driveshaft. Try changing your u-joint angle at the diff. I know you and Bubba swear it's ok to point your pinion at the t-case with a standard driveshaft but I think you have it wrong. Use some of those shims you have laying around and try to match your angles... just try it and I promise i'll never give you a hard time again.:D
 
Mine does rumble when I coast due to driveline angles. When I am next to one of those concrete dividers it sounds like I have rocks in my Tcase. It only does it on a coast. I just drove the K5 and forgot about it until Koldsimer mentioned it. My pinion points directly at my tcase also as I did not shim it when I did my flip.

Ira
 
It would also explain why it only does it on deceleration. Under load, your slip splines on the driveshaft have so much torque going through them, the fighting effect of two out of phase u-joints isn't noticeable. When coasting, there is much more slack in your slip joint which is why you can hear it then.
 
Leper said:
I've got a noise on decel that I am having trouble finding. At any speed above 30 or so, if I let off of the gas, I hear a horrible noise. A gear meshing kind of noise. ERRRRrrr ErrrrEr Errrrrrrr(best i can describe it) It almost sounds like its coming from the trans or tcase. Lots of new parts: 5.38 gears( proper backlash), carrier, master install kit.
It is a noise I had before. It did it for a long while with the other gears(4.56) and the old carrier, just not as loud. It just went away one day after wheelin. when I pulled the cover off to do the gear swap, I had alot of water in the diff. I am thinking that the extra fluid helped contain the noise.

I just added an emergency brake cable to one side, but it is not hooked up yet. It is zip tied to the frame until I get the other one and put it on. That could have something to do with it. I had cut the old half of a cable out about the time the noise stopped. Mabey I'm grasping at straws there.

The axle has alot of angle in it. It pretty much points at the tcase. I wheel with others with the same angle and they have no problems. U joints are good. It is a 241 tcase with a SYE.

If I let off of the gas the noise starts. however, if I apply the brake, it will not make the noise until I let off of the brake. Usually I have one foot on the gas and 1 on the brake. It makes the noise if the truck in in neutral or drive.

Could the hub/axle bearings cause this?(Hope so) I haven't looked at them. Could it be in the tcase? I think the noise is being transmitted through the dshaft from the rearend. I actually swapped in a different tcase and the noise didn't change.(also used a different driveshaft at that time) So that leaves the rearend, or the transmission.
I am going to recheck the backlash, but because it has done this before, I don't think that will be it
Please post up any suggestions. I am going to remove the ebrake cable tonight, just in case.
Click to expand...
i just put a 14 bolt in and i have the same problem goin over 50 and it almost seems like its the ujoint
 
sandawgk5 said:
Mine does rumble when I coast due to driveline angles. When I am next to one of those concrete dividers it sounds like I have rocks in my Tcase. It only does it on a coast. I just drove the K5 and forgot about it until Koldsimer mentioned it. My pinion points directly at my tcase also as I did not shim it when I did my flip.

Ira
Click to expand...

Been there, had that. It HAS to be the angles. Back when i had 7" of lift, it would do it bad at 30-50 mph. I dropped the t-case an inch, it helped out. Now i don't have it anymore, but i have a lot less lift too. I just called it "u joint chatter." Replace the joints all you want, they will keep doing it unless you lessen the angles.
 
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