Discuss 1966 Mustang 3rd member swap on AllFordMustangs.com, the place for Mustang enthusiasts.
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Ok, so i called to see how the car was coming and the mechanic told me that everything was done but couldnt figure out some type of whine. He said he can hear it upon acceleratoin and deceleration at higher speeds around 55-65mph. I had him swap the 43 year old 3rd member with 2.80 open differential for a 3.25 Traction-Loc 3rd member from JustRearEnds.com. He said that because they are brand new and really tight that its why they might be making that sound (and something about the paint marks on the new gears?)and when it wears it might go away?
I had this done, because, A) i wanted a little more pep out of the car, and B) because at 45-50mph it would start to give out a high pitched whine. Completely silent before and after those speeds. So i figured i should have it replaced. Now i dont know whats going on. He said that he wasnt sure why it made that sound and for me to "take it for a drive and see what you think. It might not be that bad to you." (but any sound cant be good right?)
So i guess my question is, do these types of "performance" rear ends make noise like that? I hate to have just dumped over $1,200 in parts and labor for it to not be fixed and still have something go/be wrong. Its not like i dont trust the labor either. The guy knows his stuff. Hes been in business for over 25 years and all the guys from the hotrod club go to him (thats what made me try him at first). Hes built some really high end street machines. So i dont know, im hoping its normal and will go away but if any of you know what it is please let me know. Thanks.
I don't know what it is that is wrong with it, but the paint on the gears is how he can tell if he has an adjustment wrong. If the wear is even, it's right. If it has worn more on one side or the other it will help him move it where it needs to be. Did he change out the axle bearings? Just a thought.
Ok i got the car back and have been driving it around. From what i gather, from low speed accel or decel it sounds like a faint screw type supercharger whining up or down. Its not THAT bad. At cruising its completely silent. So it WAY better then what they were to begin with. Im sorry i didnt go with a 3.55. Its a noticable increase in take off but i was expecting more. Anyway, what a difference posi make when you take off form a start. With the little bit of modifications i have that thing got sideways form the light. Wow.
their should be no whine at all. at least not from the gears, if it is wining and coast and acceleration it sounds like the pinion is set to tight in the ring gear and is hitting the face and coast side to deep. check the paint and you will know what is going on.
I have heard of people having this whining from their rear ends. I have spoken to some of these guys, and have been told that they adjusted and adjusted, and messed with it, and the only thing that fixed it was taking it back and swapping it for a different rear end. From what I have been told some of these rear ends are louder than others and you just have to insist to the company that sold it to you that it is not acceptable.
I have heard the same. That some rear aftermarket gears are louder and harder to adjust out than others. I was told yukon and pittsburgh gears are louder than motive. They are tighter at the heel of the pinion gear for strength or something. He told me to go with motive (i think that's how's it's spelled) if possible but that the others could be adjusted to make better but were noisier.
When i make a turn, left or right, it makes a pretty noticable "gear" noise. Like two gears are grinding against each other. Ive heard that some types of posi units make this sound. But i mean even when i let the car go at idle speed in the street and make a turn without hitting the gas, its pretty loud and you can feel it throughout the car. "GGGGGGggrrrrrrrrrrrruuuuuu" What the heck man! Had i known this was going to be like this i would have left it 2.80 and open.
Oh and my original whine before i swapped teh rear end out is still there too.
Im really sorry i ever started messing with this car. If only i could turn back time...
rear end are 50% black magic. its such a hit miss game first off I would get the car on a lift and check and see if the noises are really coming from the 3rd member. it could also be wheel bearings, drive shaft, trans, or engine. and you shouldn't hear a really loud grinding. it should be pretty mellow when your just coasting.....
Ok, after some talks back and forth with JUSTREARENDS.COM and some lengthy research, it appears that the ORIGINAL whine might be coming from the Side Bearings. Those are the only thing that i havnet had replaced.
As for the 3rd member and after a few consults with JRE's He is tating that it is an intaller issue. He said that the instructions have to be followed to a TEE and ONLY use Ford or Motorcraft friction modifier...
Daniel Well who ever installed the third member did not read the install instructions. They clearly state what type of oil to be used and obviously no friction modifier was added so that is why you are experiencing clutch chatter. Read the install instructions.
Just Rear Ends
We use Motive gear performance ring and pinions which are supposed to be quite. These are an import gear but are the best imports on the market; they are made in Italy, not China like most other gears. After market gears can and do make noise in some applications. There are gears made in the US such as Strange US gear, but unfortunately Strange / Us gear has been sold twice in the past year and they are not producing light duty or passenger gears at this time so they are not available. If the noise is not acceptable to you we will replace the ring and pinion at no charge, but there is no guarantee that the noise will go away. You will have to incur shipping cost and labor at your end. The noise you hear is called harmonics and does not affect the durability or performance of the rear end. Is this is the same noise you heard out of the original rear in your car? Is your cars suspension stock or has anything been changed? There is a possibility that you still may hear a noise in a replacement third member because when batches of gears are made they cut up to 300 gear sets at a time so they all could be noisy, and at the end of a batch the tooling becomes dull, therefore some gears will make noise even though there is nothing wrong with that gear setup. We have sent out several 8” third members with a 3.25 ratio and you are the only one that has had a noise issue.
You mentioned that you had the rear wheel bearings because they were leaking allove the inside of the back tires. Are you sure that they replaced the bearings or just the seals. It may be a wheel bearing making the racket that your hearing now. If it is a bearing you can put it on jack stands, start it up and put it in gear. Have someone run it up to the mph you hear the probelm and listen for it from unde the car. Make sure you block the front wheels good and be careful where you put your body parts. It is creepy under there with things moving. You can feel bearing issues pretty easy thou with a piece of dowel.
Car is back in the shop. Mechanic said there is something wrong with the rear end from Justrearends.com. He said that when he pulled it apart again, the oil looked like it was 40 years old and i had never changed it, eben though i hadnt even driven 20 miles with it. So now, i have to ship it BACk to JRE and have them go through it, My Mechanic said he called them and went over the "directions that they obviously didnt read" and it didnt say what the guys at JRE said it was, making them wrong. So now i gotta spend GOD KNOWS how much to ship this 75lbs rear end back.