Issues after gear install

[95five-0]

I got my car back yesterday from getting 4.10s installed. I had the trac lok rebuilt while it was out so I wouldn't have any issues later on. All the work was performed by a ford tech who is the one does the rear end and transmission work at my local ford dealership. My car is lowered on bmr lowering springs and has a spydershaft one piece drive shaft. Before the install the drive shaft would only hit when running 80mph or more and hitting a big pothole. I have put 120 miles on it so far so I haven't gotten very hard as far as spinning but I've kicked on it a couple of times trying to break it in first. Every time i leave semi hard on it the drive shaft hits underneath my console bad. Also when i picked it up yesterday I didn't notice any noise but driving today I noticed that when I left off the gas the rear end has a hum to it. Also I have a clunk in the back that was not there before it sounds like what a lower control arm sounds like if the bolt isn't torqued with a load. I emailed him to ask about everything and his response was he could see where the drive shaft was hitting before and that he didn't touch the LCA so they should be the same. To top it all off bama wrote my tune for 3.31 gears still so my speedometer was off and shift points are off as well as the lock up for my circle d converter. Changed the speedometer so its right now but shift points are still off.
So my problem list is
Rear end whine/hum when off the gas
Drive shaft hitting underneath console when taking off hard
Rear end clunk when hitting ruff spots in the road

Thanks for any advice you can give.

 

[Justinsmt88]

FYI, you shouldn't be driving hard on those gears at all for at least 500-700 miles after install. It's normal for them to hum a bit on deceleration. Happens when you jump to a bigger gear like that. How low is your car to the ground?

The clunk could be from a lot of things. Could be your bump stops if you didn't modify them when you lowered the car. Could also be the drive shaft, control arms or even the shocks. Or the tech might not have set the preload correctly. Where does the clunk sound like it is coming from in the rear? Is it dead center or to one side?

 

[slowlyrolling]

FYI, you shouldn't be driving hard on those gears at all for at least 500-700 miles after install. It's normal for them to hum a bit on deceleration. Happens when you jump to a bigger gear like that. How low is your car to the ground?

Gear break in is a myth, FYI.

Sounds like the gears weren't installed correctly. They shouldn't be noticeably louder than stock.

+1 for checking the bump stops. Put some lithium grease on them, then attempt to replicate the issue. If you at successful check said bump stop area for spreading of the grease.

For the tune simply email the tuner.

 

[Justinsmt88]

My car is lowered 2.25 inches and as result had to cut about an inch off the bump stops. Stopped the clunking/rough ride. Do you have a adjustable third member? If not that could be the reason the drive shaft is hitting as well as not having an adjustable panhard bar depending on how low the car is. If you have a one piece drive shaft you could be hitting on the ebrake bracket underneath. The makers of certain drive shafts have how to's for fixing the issue. When I first lowered, my rear end was out of alignment and was kicked to the drivers side with the stock panhard. I was also getting a clunk when letting off the gas from my drive shaft which was fixed by correcting the pinion angle with an adj third member.

 

[rojizostang]

a 4" ds shaft in a lowered car can bump pretty hard on hard accel or hard shifting. i had that problem when i had a 4'' ds. a big hammer, and relocating the emergency brake bracket resolved all those issues. note where the shaft is rubbing (you'll notice a shiny spot on the ds", and correspondingly massage the floor pan with large hammer.

 

[BruceH]

Noise on decel is not normal. It's the result of incorrect pinion bearing preload.

 

[kevinatfms]

Noise on decel is not normal. It's the result of incorrect pinion bearing preload.

i think it would be more pinion gear depth. preload noise would be constant while incorrect depth would account for incorrect mesh causing the backside to be too deep or shallow causing gear whine/hum.

it could be both but knowing most lazy tech's, he probably used the original pinion shim on the new pinion gear to reduce the time which caused a bad mesh pattern.

OP, i would have someone pull the cover and check the mesh first before r&r of the pinion. if the mesh is off you may need a new set of gears, especially if the pinion depth was too deep.

 

[95five-0]

The car is lowered on bmr springs so its a 1inch front and 1 1/4 rear. He said to drive the car some more and see if the whine/hum gets better, that the gears need to wear a pattern together. I do not have a adjustable upper yet. I thought at first with a 4 inch driveshaft I would need one but it never seemed to be a problem its odd that since the 4.10s its a problem. I will try beating the tunnel first to make room. If not I will get a bmr upper and maybe the upper mount if anyone suggests it. About the bump stops the car has been lowered since November and i have never hit them. Idk why it would start happening now.

 

[slowlyrolling]

The whine will only get worse. What fluid is in the diff?

 

[Justinsmt88]

The whine will only get worse. What fluid is in the diff?

Not true. I have motive 4.10s that whine on decel. I've been running on them for well over a year whine has not gotten better or worse. My stock 3.55's even had a whine on accel at higher acceleration.

 

[kevinatfms]

^they should never whine. I don't care who told you so. its a fact that a properly setup gear will not make noise.

your gears will get worse, it just may take longer than others.

oh and your factory gears were under the TSB for replacement gears as most of the 05-07 cars were. issues with tolerances of the housing machine finish caused the TSB to be issued. dealers would replace the gear set and or replace the rear end housing if it was found out of spec.

 

[95five-0]

It has royal purple 75w90 in it. And the gears are ford racing. Got them before motive started making them and relabelling them.

 

[NotaHybrid]

This thread makes me think something is wrong with my own gears because they whine on accel/decel and I always get a clunk coming to a stop and these problems only occurred after my gears were replaced.

OP get your tune fixed, but I'm sure you already knew to do that.
Sent from my helicopter

 

[2DaDarkZide PR]

FYI, you shouldn't be driving hard on those gears at all for at least 500-700 miles after install. It's normal for them to hum a bit on deceleration. Happens when you jump to a bigger gear like that.

More like 40 or 50 miles. It is just to verify if you do have wine IMO.

Gear break in is a myth, FYI.

Sounds like the gears weren't installed correctly. They shouldn't be noticeably louder than stock.

Agreed. A properly installed gear will have no sound but that is also in relation to how cheap a gear is. Some are cut so poorly they hum until they "shave" themselves. FRPP gears are great.

 

[slowlyrolling]

Not true. I have motive 4.10s that whine on decel. I've been running on them for well over a year whine has not gotten better or worse. My stock 3.55's even had a whine on accel at higher acceleration.

You're lucky. Your bearings will eventually wear out from your botched install. You should have zero whine. If you had it stock then you were low on fluid or the bearings where already going out.

 

[S197MustangGT]

I had my 4.10s installed about 3 months ago. My car makes a thumping noise on decel. "They" said it was my driveshaft but idk.

 

[2DaDarkZide PR]

You're lucky. Your bearings will eventually wear out from your botched install. You should have zero whine. If you had it stock then you were low on fluid or the bearings where already going out.

Agreed. But Motive gears are not the greatest

I had my 4.10s installed about 3 months ago. My car makes a thumping noise on decel. "They" said it was my driveshaft but idk.

Yes, that is the DS

 

[Fullboogie]

I know what "they" say about perfect gear installs. But I can say that after having gears installed in over a dozen cars over the years by some of the best shops around, every single one of them made some extra noise compared to stock. And most of the time, it was a bit of whine on decel. In fact, I can't say I've ever been in a car with aftermarket gears that didn't have a little bit of noise. That doesn't mean it's right, but I'm not worried about it at all.

Also keep in mind that a lot of guys do gears, LCA's, DS's, etc. at the same time. These other parts (particularly control arms with poly bushings) transmit more drivetrain noise.

 

[2DaDarkZide PR]

I know what "they" say about perfect gear installs. But I can say that after having gears installed in over a dozen cars over the years by some of the best shops around, every single one of them made some extra noise compared to stock. And most of the time, it was a bit of whine on decel. In fact, I can't say I've ever been in a car with aftermarket gears that didn't have a little bit of noise. That doesn't mean it's right, but I'm not worried about it at all.

Also keep in mind that a lot of guys do gears, LCA's, DS's, etc. at the same time. These other parts (particularly control arms with poly bushings) transmit more drivetrain noise.

Then they weren't the "best" hehe.

3:55 to 4:10s and 0 whine. The gear quality plays a factor.

 

[95five-0]

From what i heard the gear quaility is what was would cause whining. Would the sway bar and panhard bar being tightened without load on them cause my clunk? The installer said he tightened everything in the air. Also beating my tunnel would get the drive shaft to clear but if my problem is pinion angle and it would help to get a new upper I will. Just dont know if it worth doing the new mount and poly bushing in the rear end housing.