Do I need a Diff drop?

I am about to install the bilstein 6112 at the top setting for 2.5 lift. Most places say anything 2.5 and under do not require a diff drop.
The concern is that if I have a "lean" toytec advises to add a .5" shim to drivers side to correct the lean. I'm no mathematical rocket surgeon, but that seems to add up to 3" now on one side.
Toytec also says anything over 1.5 needs a diff drop, contrary to most advice I've seen.

Any thoughts on this?

 

It’s cheap and takes 10 min to install. Id say do it. I had a slight shimmy when taking off with the 6112s at 1.9” setting.

 

Good call.
Did you have a lean at all with the 1.9 setting requiring a shim on one side?

 

I did and added shims but it didn’t change the lean at all. I’ve changed to icon and have them set the same and didn’t worry about it.

 

There is literally no reason not to do a diff drop. It can only help. It won't reduce ground clearance or cause any other issues and will just help your CVs last longer.

And yes, you should also do a carrier bearing drop as well.

 

Unless you're doing long travel and it should be removed. Ask me how I know lol

 

There is no reason to not do a diff drop unless you are doing long travel. Otherwise, it can only help.

 

Check your cv angles after the lift. Anything under 10 degrees and you probably don't need it. Also as long as the boot fins don't rub each other. I did a 2 inch lift and the angles only moved a few degrees. I'm at 6 and 7 degrees.

 

6 and 7 degrees is still worse than 3 or 4 degrees.

A diff drop takes all of 5 minutes to install. Worn CVs take considerably longer, so why not take 5 minutes now to make those last tens of thousands of miles longer?

 

So I read too fast and was thinking carrier bearing drop, not diff drop. I have about 2.5” of lift and no diff drop and my cv angles are good. I strongly recommend the carrier bearing drop though.

 

Because there are multiple, reputable truck builders on this forum that never advise to use them because it changes the pinion angle of your driveline through the differential.

Also, the pro comes factory lifted without a diff drop. Which is 2 inches or more.

 

Yes. And the driveline and its u-joints are much cheaper and easier to replace than the CVs. They are also put under less of an angle increase with the diff drop AND the angle stays consistent since the diff doesn't move.

Any time you are going to lift a vehicle you are going to increase wear somewhere. May as well put it in the place easiest to repair.

Tundras also used to come from the factory with a supercharger. Doesn't mean those engines were going to get 350k - 1M miles though.

 

No, the diff drop does not help on a Tundra. Don't do it!

 

You aren't wrong but no offense , I'll take the advice of guys who do this for a living and have build hundreds of trucks.

 

First of all, welcome from TX!

Second, nice Chappelle Show reference.

Third, I wouldn't do a diff drop on anything that minimal. Once you go 4" or taller it's time to think about diff dropping.

Fourth, do a carrier bearing drop.

 

eh. I'm so over the opinions of "experts".

The last several "experts" I talked to about my tundra told me it was impossible to fit 37s on a tundra with less than a 6 or 8 inch lift. Yeah, maybe they spend all day, every day, building Tundras with 8inch lifts and 37s. But if they haven't ever tried to fit 37s on a stock truck or on a 3in lift, then what the hell good is their opinion in the first place? The fact that they don't understand that lift height doesn't matter for tire fitment on an IFS truck in the first place....

Also, those experts are saying not to do it because they don't think it is 100% necessary. And they are right. It isn't 100% necessary. But they aren't thinking long term. They aren't thinking about having to pay for new front half shafts/CVs in 5 years time. These are probably the same experts recommending King/Icon/Fox coil overs with uni-balls and poly bushings to guys who just daily drive their trucks with MAYBE some light fire road off-roading, never mind that those uniballs and poly bushings will have to be replaced every 20k miles if not more often..

I don't hold anybody's opinion in higher regard than anybody else's. I double check everything that anybody tells me before I believe it myself. Unless somebody can make a very good case as to WHY they think what they think, I don't really care. Just saying "Trust me bro, I build Tundras all day" isn't good enough for me.

 

Can you explain why you think a carrier bearing drop is necessary but a diff drop isn't, even though the angle changes of the rear driveline are MUCH less severe than for the front half shafts?

 

The rear driveline is much longer and amplifies rotational balance issues more significantly. The interdependency of two shafts also creates a bigger problem once angles are off. Look at how your truck will initially shutter at takeoff when the rear angles are off.

 

You can check for yourself, as I did with an angle meter. It is an insignificant change on the CVs at 2" and based on how the numbers changed the others on here are correct that you probably wouldnt get a benefit until about 4 inch or up but at that point most guys go the subframe route. The Pro is enough proof for me to put a nail in the coffin of the debate. If 2 inch didn't need it but 2.5 did Toyota would have put it on since they are usually overly cautious. That tells me your probably ok till 3 or more inch.

 

I get what you are saying, but adjusting the mounting height of the carrier bearing doesn't have an effect on the drive shaft's rotational balance. The shafts are balanced off the truck in a machine after all, and as long as they aren't physically damaged, they will remain balanced no matter how they are mounted.

Also, the interdependency of the two shafts would only really matter if both shafts could move while the suspension articulates. But since the forward shaft is mounted rigidly to the truck and only the aft shaft can move, it is really no different to having the shaft attached directly to the rear of the transfer case/transmission.

I have come to the conclusion that the shutter at take off in the Tundra is due to the rear of the frame being excessively flexible. I believe this is probably also the source of the infamous Tundra "bed bounce" issue on concrete highways.

All of that being said, I do also recommend a carrier bearing drop. I am just saying, I would also recommend the diff drop.

 

I don't think you are understanding what I am saying here.

I am not saying that your diff will explode of your drivelines will shoot out of your truck within 5 miles of driving.

I am saying there is NO DOWNSIDE to installing the diff drop, and they can only provide a benefit. Also, they take next to no time to do, so he may as well install them since he already has them in hand.

I get it. The angles aren't that extreme. They won't cause that much more wear. However, just because it isn't extreme angles that doesn't mean there isn't more wear, and if installing the diff drop can mitigate that, I see no reason not to do so.

 

See I think that point where the carrier bearing is definitely flexes when acceleration kicks in otherwise there wouldn't be a bushing there. That point isn't static. I could see what you're gettin at though...ladder/traction bars to address what you mentioned maybe...axle wrap is a definite in lifted and/or SC'ed applications.

 

Can you link a drop kit you have in mind?

 

The OP said his lift came with a diff drop kit, so if he has one in hand, I would just install it.

That being said, I ordered this one alongside the lift kit I ordered from the same company.

https://ironman4x4america.com/differential-drop-spacer-kit-for-2007-2021-toyota-tundra/

It appears to be sold out right now, but they are all essentially the same. Just two longer bolts and some spacers, usually made of either aluminum or some sort of polymer.

As for the carrier bearing drop kit, I ordered one of these, again from the same company...

https://ironman4x4america.com/drive-line-spacer-kit-suits-2007-2021-toyota-tundra/

But when I got the kit, I found that it came with a carrier bearing drop already, so I have an extra one that I am looking to sell. $20+shipping if anybody is interested.

 

OP, are you able to discern the correct answer through all of this? Welcome from LA (Lower Alabama)!

 

The advice I'm getting on and off this forum points to:

Install the components the way I want them.
If it leans, deal with it then.
If there is a vibration deal with it then (carrier spacer)
If the cv angle is too much different measured before and after, deal with it then (diff drop)

My instinct is to put in the $50 worth of spacers if they do no harm.

I am new in this Tundra world from 25 years of owning 1 ton diesels of various manufacturers, I am here in search of reliability and longevity so whatever I can do to help that I will.

Also, I have no children, so I'm not able to afford the first born child downpayment on a new diesel.

 

BTW the spacer to correct lean does just that, it doesn't matter if it's a spacer the end lift result is still the same height wise.
A 2.5 inch lift is still 2.5 inches whether or not u use a shim so overall lifted height is what matters.

 

I understand exactly what you are saying my friend, I work as an engineer. Granted I am not an expert or an auto engineer but the disadvantages you say don't exist actually do, as I stated with the pinion angle of the front diff, which is what the people also stated that build alot of tundras. By all means do it if you feel it's necessary, alot of people on here do it.