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Is your 16 xpt4 front diff extremely loud or quiet over 30 mph?

  • loud

    Votes: 107 75.4%
  • quiet

    Votes: 35 24.6%
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OH NO,, not doing it, just curious. Thanks for the reply. I know people with the older 4x4 trucks would sometimes pull the front drive line and run them. As far as the weeds wrapping, seems it would do that with or without the shaft. In any case, again thanks for the reply. I have pulled the shaft on my old 2010 and not really wanting to do it again
 

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Polaris uses NET Forged straight bevel gears in the front drive(not a differential) in these units. They are net forged gears meaning there is no machining on the ring or pinion face(cost savings) they are strong but very, very, loud and they have a very high NVH. This is not a cut spiral bevel gear set like in a traditional front or rear differential in an automotive application that most people use as a benchmark for NVH.

It is what it is and they will be loud until Polaris changes to a cut gear set in the front drive. That will be more cost or more LCC parts.
 

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Locomike
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Good point.
For those who have never split their diff to inspect or repair,
The entire ring and pinion have a 'cast/sand blast' type surface.

True automotive gear sets will be polished to a specific surface specification and then,
interference fit/shimmed for obvious reasons.

Knowing that, even if one were to disconnect either shaft or the diff magnet,
the front axles will still be spinning the ring and pinion under certain circumstances if not all the time.
Not enough to turn a wheel on its own, but under zero load 'I THINK' the gears would still spin.

Pros..... please verify or teach me otherwise as I am sincere in asking.

My engineering experience will get me a cup of coffe 'sometimes' and that's about all it's worth if your not experienced in the field you are currently discussing.
Kinda like going to a Gynecologist with 30 years of experience when you have a brain tumor.

As you may suspect I've run into many who's opinion begins with 'I'm an engineer, therefore I must be right).

Experienced (my term for Pros), many who do this 80 hrs a week for a living are appreciated by me on these forums.
Sorry for the rant...........
 

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Locomike
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Some examples of my 2nd diff ring and pinion bear, in process of rebuild as parts arrive.
Notice the teeth on both gears. The contact surface is rough as is typical of a Garden Tractor application.

I'm throwing out a business opportunity to some of the excellent machinists on this forum.
If a jig could be constructed to ground and repolish the teeth at the correct angle, I think many would use this service (If it doesn't already exist).

Thanks VinnieMaxx as is usual I overlooked the common sense issue. I don't think I have read this obvious observation of at least one source (of many).

One day, a manufacturer will be designing a hydrostatic drive for these machines and all of this will be a bad memory.
 

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Straight bevel gears are noisy period. That being said my 2016 XP1K is pretty quiet I cannot even hear it at all. You can remove the drive shaft to the front drive if you want no code will be generated. The front drive is a over running unit. All of the parts are moving all of the time but no torque is transmitted to the front tires unless the 4WD switch is active and rear tires slip or spin in mud, sand, snow or whatever now the back tires are spinning at the same over running speed (ratio) of the front drive and torque will now be transmitted through the front drive to the tires. Rinse repeat.
 

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Locomike
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Cut and pasted from Straight cut gears vs helical | Automotive Thinker - Discussing the finer points of automobiles


So why are straight cut gears used in race transmissions? Well, there is only one real reason, and that is because straight gears don’t produce any axial loads (thrust loads). Its very easy to build strong gears that are either straight cut or helical, so that’s not the problem. The problem is when you start putting a lot of torque through helical gears, the axial loads become so high that you need a very strong transmission case and shafts (axles) to contain the loads; this can add significant weight to the transmission. Straight cut gears simplifies the transmission case design and also the types of bearings used. This allows for a very light weight transmission to be designed – and we know that weight is everything in a race car. The one negative of straight cut gears, and its a big one, is that they produce a lot of noise.
 

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Cut and pasted from Straight cut gears vs helical | Automotive Thinker - Discussing the finer points of automobiles


So why are straight cut gears used in race transmissions? Well, there is only one real reason, and that is because straight gears don’t produce any axial loads (thrust loads). Its very easy to build strong gears that are either straight cut or helical, so that’s not the problem. The problem is when you start putting a lot of torque through helical gears, the axial loads become so high that you need a very strong transmission case and shafts (axles) to contain the loads; this can add significant weight to the transmission. Straight cut gears simplifies the transmission case design and also the types of bearings used. This allows for a very light weight transmission to be designed — and we know that weight is everything in a race car. The one negative of straight cut gears, and its a big one, is that they produce a lot of noise.
Which I would be completely on board with if all RZRs sounded the same but they don't.
 

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Bringing this back to life.

Ever since I rebuilt my RZR I have a terrible metallic rattling/grinding noise that gets really loud about 6,400 rpm and goes 90% away at 7,100 rpm. It is there in AWD or 2WD and low or high gear. It’s strictly RPM dependent.

I’m running a 2019 Turbo diff that has the factory shim between the pinion gear and bearing. I installed the complete Sandcraft bulletproof kit(bearings, sprague, armature plate ect)

For the first couple hundred miles I thought it was the stainless inserts in the primary clutch or an exhaust rattle until I rode in the bed while a buddy drove and I could not hear it from the bed. I then pulled the passenger seat and laid on the floor while my buddy drove and it definitely sounds like it’s coming from below the console in the pinion area.

I have changed the fluid twice in the front diff and no metal shavings or chunks. I dropped the skidplates and could not see any signs of anything rubbing(thought maybe coolant lines).

Before I pull the front diff to inspect, I had a question for the guys with the “marbles in a can noise”. Is this noise happening at all RPMs? I find it hard to believe a front diff issue would only present itself in such a small rpm range. Up to 6,000 rpms it’s dead quiet. At 6,000 you start to hear it, it’s loud by 6,400 until 7,100 and then it quiets right back down again. I would think if it was a diff issue it would be loud all the time.

The driveshaft and carrier bearing are new. I have inspected clutches and they’re fine. Right now I’m leaning towards it either being the front diff or I have something rattling up front I have not found yet.
 

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2015 Xp4 1000: Had the “marbles in a can” sound in front drive unit when new. Did the Sandcraft bearing kit to resolve. At time of installation, washer shim for pinion to ring gear mesh would not allow bearing to be pressed in deep enough to allow snap ring to be installed. Removed shim washer, reinstalled bearing, and put unit back in vehicle. That was at maybe 2000 miles or so. Vehicle now is approaching 20,000 miles. No “marbles in the can” sound anymore. I’ve been in the drive unit several times since, and gear pattern is good as well as the bearing.
Its not that I wanted to keep the shim washer out, but, it just wouldn’t go back together with it. In my case, I think it changed the contact patch enough on the net formed gears that a happy place was found.
 

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Locomike
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I chased a noise that would only be noticeable when 'under load' as in when he RPM was on a he way up.
It drove me crazy as I had everything apart including the diff and couldn't find anything out of spec.

It ended up being my snorkel gear. Wait for a pro to verify this but it's my understanding when sitting 'parked' grab the drive shaft and check for play back at your output shaft. There shouldn't be any.
If you can get it to 'clank' with some wrist action then your backlash is the source of the noise.

Again, this is a big repair, so let's get verification from a Pro.
 

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I’ve had the transmission apart recently, I’m 99.9% sure the snorkel gear is set properly.

I’ve been digging through old threads and watching some videos and they lead me to believe it’s the diff. My previous diff was the stock 2017 XP4 1000 diff and it was dead quiet still when I sold it with 1,699 miles on it. It did not have a shim inside. Seems like the majority of noisy diffs are the ones with shims.
 
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