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5/07/2019 10:31 AM  #1


repetitive noise only at 5 th gear , at highway speed

Hello all, 
i got a repetitive growl , wave , noise coming from under . It's not a ticking but a whining repetitive  , something like an old bearing . 
Sound strange it's only at highway speed , more or less from 60 to 75  mph  and is not going faster if i go more fast . 
This thing is matched with a vibration on floor stick , but only with 5th gear. 
this vibration is fast and i can feel it touching it , and is quite a lot . 
I don't know what can be the reason but all this came out after i put my car at top speed , pedal to metal until i realized she can give me more.  From that moment i got noise coming from some part that i can assume are :  clutch , transmission ( but i don't know what can be )  , differential ( i don't feel coming so rear ) . 
More or less is coming from "center "  ( clutch/ trans )  of under car . 
Any suggestion is welcome
thanks as always !

 

5/07/2019 4:30 PM  #2


Re: repetitive noise only at 5 th gear , at highway speed

If it happened after a "speed trial" you might want to check for a thrown driveshaft weight. 

BB


"you get what you pay for, good work isn't cheap, and there are NO free lunches...PERIOD!"
 

5/07/2019 6:52 PM  #3


Re: repetitive noise only at 5 th gear , at highway speed

See if the exhaust system is rubbing / touching the body?

Pull the transmission cross member to see if there are witness marks where it touches the transmission. My car has had that problem.

Has one of the motor mounts collapsed, fatigued, broke caused contact with the frame?

Happy hunting, it can be a royal pain in the backside to solve.


John  -- 67 Mustang Coupe 390 5 speed
 

5/08/2019 8:58 AM  #4


Re: repetitive noise only at 5 th gear , at highway speed

Does it go away when you push the clutch pedal in?

 

5/08/2019 9:51 AM  #5


Re: repetitive noise only at 5 th gear , at highway speed

TKOPerformance wrote:

Does it go away when you push the clutch pedal in?

i need to try again cause i was managing the exhaust and today is raining ,  as far i remember no , still remain noisy . 
What do you think about manual stick that chatter ?

i got feeling that clutch pilote bearing or  driveshaft angle are involved in that 
 

     Thread Starter
 

5/09/2019 4:39 AM  #6


Re: repetitive noise only at 5 th gear , at highway speed

If it goes away with the clutch pedal pushed in then its something in the clutch, if not then its elsewhere.

 

5/09/2019 12:08 PM  #7


Re: repetitive noise only at 5 th gear , at highway speed

TKOPerformance wrote:

If it goes away with the clutch pedal pushed in then its something in the clutch, if not then its elsewhere.

TKO , please do you know how to adjust angles between engine /trans/ driveshaft  . ?  i take some measures with inclinometer today , but dont realize me too much . 
I dont know if there is a way to shim and change the axle angle. 
I need to change engine mount or trans mount ?
/This what i found :  slip joke 3.5  °     /  driveshaft 0.75°    /   rear axle  2.50 

     Thread Starter
 

5/09/2019 3:58 PM  #8


Re: repetitive noise only at 5 th gear , at highway speed

Raising or lowering the rear of the transmission can change the front angle.  Shim the trans mount to raise it, modify the crossmember to lower it. 

The pinion angle can be changed with tapered shims under the leaf spring pads.  Make sure to use new u-bolts when you do that; they are not reuseable. 

 

5/09/2019 4:23 PM  #9


Re: repetitive noise only at 5 th gear , at highway speed

thanks !

     Thread Starter
 

5/09/2019 4:44 PM  #10


Re: repetitive noise only at 5 th gear , at highway speed

Something real simple is shift handle handle touching opening?

 

5/09/2019 5:12 PM  #11


Re: repetitive noise only at 5 th gear , at highway speed

TREMEC Toolbox is a smart phone app that will give you a pass or fail rating for drive line angles.

If you get a fail, I’m not sure it can tell you what to look for to correct the problem.


John  -- 67 Mustang Coupe 390 5 speed
 

5/09/2019 8:53 PM  #12


Re: repetitive noise only at 5 th gear , at highway speed

Generally, what you are looking for in angles are for the differential angle to be around .5 degree less than the engine/trans angle. This is to account for the spring wrap that causes the pinion to rise when power is applied. For more powerful engines and more 'spirited' driving/racing, some prefer to have around .75 to 1 degree less angle than the engine/trans at the rear. Using your numbers, you would want to change the engine trans angle to 3 degrees or raise the pinion angle to 3 degrees (+.5 degree).

If you have the tunnel clearance a shim under the trans mount would be the easiest way to change things up. That's what I did when I was aligning mine and it works great.

 

5/11/2019 2:51 AM  #13


Re: repetitive noise only at 5 th gear , at highway speed

Jim Bowie wrote:

Something real simple is shift handle handle touching opening?

no , it's free to play 
 

     Thread Starter
 

5/16/2019 12:14 PM  #14


Re: repetitive noise only at 5 th gear , at highway speed

351MooseStang wrote:

Generally, what you are looking for in angles are for the differential angle to be around .5 degree less than the engine/trans angle. This is to account for the spring wrap that causes the pinion to rise when power is applied. For more powerful engines and more 'spirited' driving/racing, some prefer to have around .75 to 1 degree less angle than the engine/trans at the rear. Using your numbers, you would want to change the engine trans angle to 3 degrees or raise the pinion angle to 3 degrees (+.5 degree).

If you have the tunnel clearance a shim under the trans mount would be the easiest way to change things up. That's what I did when I was aligning mine and it works great.

Thanks , i am trying some shims under transmission , checked again , and take a ride . Incredibly much more better and  groal sound is very few or desappear .  Seems that really was a pinion angle issue . This is a first step , then i will handle rear axle or engine mount . 
thanks for precious info
 

     Thread Starter
 

Board footera


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