2017 TRD Off Road now stock with an axle shim

If the gears in the diff are the howl then driveline angles have nothing to do with it.

I don't have the howl so I have tried to keep out of that discussion. People try to put blinders on and ONLY look at Tacomas when discussing the Tacoma howl. Do a search on diff or rear end howl and you will find a shit ton of drag race guys who straight up say some gear sets howl no matter what.

My opinion on howl is either the gearset tooth angles or setup. The other option is the actual machined sections of the third member. It may be off slightly which makes getting the ideal setup a bit of a compromise. If you have ever set up a diff gearset there is the ideal pattern you want but the relationship of the machining to the other components may mean your backlash is correct, the pattern is centered on the tooth crown to root but the pattern tends to be to one end of the tooth. No matter how much you try some things can't be made to pattern perfect and that is just how it is. It will work just fine and be just as strong. It may just make a bit of noise or nothing at all.

I am NOT a full time drag racer or an automotive engineer. All I have is my theory based on my personal experience. Now back on topic - the shims are for ujoints angles and NOT gearset / diff howl or related issues.

 

Without even looking I say down. Under hard acceleration pinion rises opposite of tire direction so you shim down 1-2 degrees to compensate for this. (Or weld spring perches to allow for this with no shims).

 

I get what you are saying but the howl is a problem for a ton of people on here and there have been remedies in the past that include changing the drive line angles. There is a TSB a member posted from a Lexus howl issue that involved adding washers to where everything bolted together to change the angles.

So while you might be right, there is credence to this shim = howl fix discussion. I don't want to dismiss it entirely until we've had members confirm they have the shims and the howl.

Honestly, that would explain why some members have it and some don't and why it appears over time and gets worse. If the angles are off it will howl or if the become out of wack due to suspension settling in that would explain a lot.

 

I have the shim and I have a slight whine at light throttle. Do not have any vibration tho.

 

There is a difference between a howl and a noise. Just because you have a noise doesn’t make it a howl. There is no debate that some people have what they describe as a howl.

I read about all of the driveline / driveshaft angle issues. I have not read a single one I would describe as having a howl. Yes they make noise. Now a gearset they can HOWL like in your rear diff. Now regardless of my experience and training I could be wrong and u-joints could howl or carrier bearings could howl. But any SQUEAL I hear from a driveshaft is about to let go like NOW.

In time we may learn the true cause of the howl or at least know what occurred to make it go away. But my money is on something other than a spring shim. I spend my day fixing industrial equipment so I get to listen to lots of stuff make noise for decades and other noises very short lived before the internals make a break for freedom. Some gears are inherently quiet and others are inherently noisy. When you try to go for frictionally efficient it tends to get noisier. That is why some gearsets are less efficient and much quieter. Now we all know the Tacoma 3rd gen made some big changes towards fuel efficiency which I propose may have included the rear end gearset tooth profiles and the helix. This may have resulted in some units making noise due to the combination of the tooth profiles and the backlash /setup.

I am of my opinion regarding the howl but until I hear it for myself I can only theorize. I can only base my post on experience and training of similar noises or situations which cause me to consider or dispute the theories of others I read here. I do see situations that don’t fit the usual diagnosis so I won’t say driveshaft or shims aren’t part of the howl / fix. What I will say is they tend to make OTHER noises so the widespread reporting of a howl sounds like something other than driveshaft or carrier bearings. It would be awfully bizarre that a DS made a NEW noise never associated with a DS before and it wasn’t a one off.

 

I am in the same camp as you that l do not think the howl is coming from driveline angle but is from the actual gearset.

 

measure front height of shim, rear height, length... find highschool student who remembers how to do maths, have angle derived. done.

 

There is a giant thread where 450+ people hear it howling.

 

I thought the 45 to 60 mph howl was do to drilled holes near the front of the truck. Talked about in this thread linked below


https://www.tacomaworld.com/threads/solved-howling-noise-between-35-45.410480/

 

My understanding is the Shim is part of the driveline vibration fix. The TSB was issued December of last year and new builds following that date should have had the updated leaf springs included if applicable.

The actual TSB is in the stickies and describes replacing with the new leaf packs based on driveline angle measurements.

OA

 

No, that's the LCA flute issue. That typically occurs at lower speeds. I've had that TSB executed which fixed that issue. The rear diff howl poll thread that has over 1000 responses which is 50/50 for people experiencing it.

It's a 400hz howl that can be incredibly loud around 55-65 mph. The reason I *do* think it's drive angle related is because: several people have noted vast improvement or completely eliminated it by lifting their trucks and because there is a TSB for a Lexus for this same issue (granted for a sedan) which remedies the issue by adding spacers/washers to the diff mounts to change the angles.

It may be the gears, but there is evidence that it's angles.

 

I have a 2017 DCLB OR that I purchased in Feb. Don't know if the extra 13" in wheel base for the long bed negates the need for the new shims.

I just went outside and I don't have the shims, I do have the howl.

Also noticed that i have rubber isolaters between the leafs so I shouldn't have the leaf spring squeaks, either?

 

That's the LCA howl that typically occurs with crosswinds. Speed isn't the main factor and a TSB has been issued for plugs for those holes (I believe new trucks come plugged).

The diff howl that is still plaguing trucks occurs between 50ish and 60ish mph when feathering the throttle. It's easily replicated with driver input if the truck has it. Toyota's semi-official fix per the forum at the time is a 3rd member replacement, which can also develop the howl.

OA

 

Do you notice any vibration in the gas pedal under load?

 

As the other guys already said, the Lower A Arm Whistle is a seperate issue and they now come plugged from the factory.

 

The picture shows that the pinion is shimmed up. Think in the back , thin in front.

 

they are putting them in because it's a TSB. Stickied here too.

https://www.tacomaworld.com/threads/oh-no-tsb-0171-16-driveline-vibration.463992/

 

Rumble strip vibration when rolling to a stop was the cause of at least one Lemon Law on a turd gen that i'm aware of... they started doing this not too long after

 

I have the 2017 TRD OR with about 2,300 miles on it so far, and get the howl when I feather the throttle between 54 to 57 mph.

 

https://www.tacomaworld.com/threads...oise-howling-when-feathering-throttle.442341/