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Gear Whine / 3 link rear end

1495 Views 42 Replies 16 Participants Last post by  Harryburroughs
Hey Guys,

Ive been chasing down terrible whine / gear noise for months. I will post a link to the noise and hoping to see if anyone else has had something similar and if they resolved it. The noise is there all the time but cannot really hear it until 50mph then when she's in overdrive its overbearing... If I dip the clutch the noise goes away.

I have a quick performance 9 inch rear end with less than a 1000 miles on it... Its got 3.70 Motive gears along with a SOT 3 Link kit. My current shop said it may be the diff or 3 link so I had the centre section removed and the back lash set up again, axle straighten and I still have those dam noise. Quick performance are blaming the suspension company, the suspension company have said they have not had this issue previously so im just in the middle with a great driving restomod which I cannot stand to drive on the freeway....

Work ive done...
Suspension is new.
Diff is new
Back lash has been set up again
Axle has been checked and straighten
Axle bearings have been replaced
Tyres are brand new
Driveshaft has been balanced
New UJ's

Cheers.
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Well Harry, the first thing I noticed is you are driving on the wrong side of the road. :ROFLMAO: Just kidding. If I had to go out on a limb, I would say that the noise is coming from the mating of the gears. Just my opinion. I don't know why some gears seem to make noise. I had a 1983 Mustang, 7.5" rear. Backing out of the garage slowly, the car came to an abrupt stop. Pulled it back in, took it apart and a spider gear tooth had broken off and had somehow gotten between the ring and pinion and that's why the abrupt stop. Not much really noticeable on the ring an pinion.
I bought a new Ford posi unit and installed it. No problem, set the backlash. I never got the whine out of that rear end. I even paid a "expert" and same result.
I thought I remember someone recently having problems with a rear end with Motive gears?
Personally, I like Richmond gears. They come from the factory with the pinion depth and backlash scribed on the gears, of the setup dimensions used at the factory to run the gears in. I set them up to those dimensions and have never had a problem.
I am not saying to run out and change your gears, but if you are pulling your hair out trying to figure it out and you are throwing out money chasing this, it may be worth your while to install a different brand of gear.

Just thinking of this, you may want to check the drag on the pinion bearings to see if the gears were set up too tight as far as the pinion bearings. Just a thought.
 

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The Motive and Richmond brands have been owned by the same company since '15. So the parts inside the boxes may not be as different as they once were.
That's interesting. I didn't know that. Glad you mentioned it. I was doing some research after reading your post and it seems there might be 2 lines of Motive, the high end made in Italy and second tier made in Asia. I have a set of Richmond gears in the box I plan on using. It looks like Richmond has a second tier version called Excel. Looks like Richmond still has a facility in SC. , hope they work out. (y)
 

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@Harryburroughs I have the same setup you have with the same vendors. Everything from SoT has been right and everything from Quick Performance has been wrong! You will get a bit more noise transfer with the short upper link but it is very minor in my car. How can QP can blame SoT for a gear whine. My QP axles slap around in the center section at low speeds because they are too short and machined undersize.
 

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Sorry, but Richmond was all over the place in quality when I sold R&P sets at JBA in the 89/90 time frame and that was when they were
making their stuff here in the US. We got a lot of them back...... I (unfortunately) did RGA's in their warehouse as well.
 

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Discussion Starter · #9 ·
@Harryburroughs I have the same setup you have with the same vendors. Everything from SoT has been right and everything from Quick Performance has been wrong! You will get a bit more noise transfer with the short upper link but it is very minor in my car. How can QP can blame SoT for a gear whine. My QP axles slap around in the center section at low speeds because they are too short and machined undersize.
Hey buddy, I agree I love the SOT stuff. Quick performance have said the upper link and joints are to blame for this noise…. Basically told me without changing my suspension. I can’t get rid of the noise and having a 3 link from SOT will cause noise to come directly in the cabin. The noise is even worse in person it’s unbearable for long journeys.
 

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Discussion Starter · #10 ·
Well Harry, the first thing I noticed is you are driving on the wrong side of the road. :ROFLMAO: Just kidding. If I had to go out on a limb, I would say that the noise is coming from the mating of the gears. Just my opinion. I don't know why some gears seem to make noise. I had a 1983 Mustang, 7.5" rear. Backing out of the garage slowly, the car came to an abrupt stop. Pulled it back in, took it apart and a spider gear tooth had broken off and had somehow gotten between the ring and pinion and that's why the abrupt stop. Not much really noticeable on the ring an pinion.
I bought a new Ford posi unit and installed it. No problem, set the backlash. I never got the whine out of that rear end. I even paid a "expert" and same result.
I thought I remember someone recently having problems with a rear end with Motive gears?
Personally, I like Richmond gears. They come from the factory with the pinion depth and backlash scribed on the gears, of the setup dimensions used at the factory to run the gears in. I set them up to those dimensions and have never had a problem.
I am not saying to run out and change your gears, but if you are pulling your hair out trying to figure it out and you are throwing out money chasing this, it may be worth your while to install a different brand of gear.

Just thinking of this, you may want to check the drag on the pinion bearings to see if the gears were set up too tight as far as the pinion bearings. Just a thought.
I was thinking for changing the gears but trying to get a define answer as I probably wasted 1000 bucks changing the bearings, doing the re lash, Straightening the axle
 

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You already know where the issue actually is............. I don't know what more to say.
 

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I was thinking for changing the gears but ....
I guess some people in here would have loved to see a pic of tooth pattern. I've had a new rear that whined, despite it was built by a guy that build Ford axles for a living. The pattern looked wrong to me, and a homemade readjusting to something that looked better, removed 95% of the noise. I've gotten the understanding that a lot of the aftermarket gear sets are really sensitive regarding the setup, if you want them to be silent. Something about that they are machined with a different process than the OEM gears.
 

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following this post, as I recently purchased the SOT 3 link for my 69 coupe but haven't installed it, yet. I doubt it's the suspension as its sounds like the gears to me. best of luck and hope its an easy fix.
 

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Hey buddy, I agree I love the SOT stuff. Quick performance have said the upper link and joints are to blame for this noise…. Basically told me without changing my suspension. I can’t get rid of the noise and having a 3 link from SOT will cause noise to come directly in the cabin. The noise is even worse in person it’s unbearable for long journeys.
The noise I get from the upper link is a mechanical things going round and round noise not a whine. It's not bad even with all sound deadening having been removed. I'm sure some modern sound deadening material would almost completely eliminate it in my case. If I hadn't promised myself that I wasn't going to take the car off the trailer until April I'd drive it and post a video.

Do yourself a favor if your doing the SoT 3 link and get everything from Shawn. He uses good components from good vendors. I believe he uses Strange Engineering for axle components. It will be right the first time. I ended up spending more for less with QP and I still need some properly machined axles.
 

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Discussion Starter · #16 ·
I guess some people in here would have loved to see a pic of tooth pattern. I've had a new rear that whined, despite it was built by a guy that build Ford axles for a living. The pattern looked wrong to me, and a homemade readjusting to something that looked better, removed 95% of the noise. I've gotten the understanding that a lot of the aftermarket gear sets are really sensitive regarding the setup, if you want them to be silent. Something about that they are machined with a different process than the OEM gears.
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The 3.70 gear is known to be a bit noisy. I knew this when I selected it ,again. I’ve had an N case for years and have only put 3.7’s in it and all of them have been noisy. So much so I blame the case. I’ve done several other gears in other cases with no problems.
That said I had Quick do a REM polished 3.70, Stange S case with a TruTrac and it’s quite as can be.
Currie had a disclaimer about noise with 3.70’s ,they will do a 3.75 though.
Hunting gear sets tend to be a bit quieter . 3.25,3.89,3.91,4.11
 

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Not too long ago in a FB group, don’t remember which one a guy set up his own gears, posted a picture of the mesh asking how he did. Now I’ve looked in shop manual and seeing what gear mesh should look like and they looked good to me. But that doesn’t mean anything. Of course there had to be a big discussion on it. Quite a few people who actually did this type of work chimed in. I don’t recall all the details but what can cause whine is the type of use the gears will be used in. A couple said for drag racing I think the backlash was set tighter and I think would cause noise. Maybe look into this? Find a shop that does more race type of work and see what they say.
 

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I believe it’s the Rear end but the local axle shop blamed the top link too so I’m not making any progress View attachment 869694
You should probably go with the rear gear being the noise source…….
I’ve run a few rear axles where the leaf springs are mounted via mono ball. No noise transmitted. And definitely nothing coming from the Ford gears in the 9” at speed.
Solving the source of your noise is where you’re at now.
 
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