Question on "new gear" break-in.. Different scenario.

[Hoooper]

so, he makes like 320 ft lbs at the flywheel and then a doubler so 4:1. compared to 750 at the flywheel and 2:1. Im not seeing this huge difference

edit: hes probably not towing 15,000 lbs either

 

[MoparManiac]

so, he makes like 320 ft lbs at the flywheel and then a doubler so 4:1. compared to 750 at the flywheel and 2:1. Im not seeing this huge difference

You are terrible at math. A doubler with a 231/300 does NOT equal 4:1.

Start with 300 ft lbs at the flywheel.

1st gear in that transmission is 5.61:1.

Multiply by the low range of the first t-case 2.72:1.

Multiply THAT by the low range of the second t-case 2.62:1.

That's the output to the axles. Nevermind the fact he's running 4.56s and most new light duty diesel pickups are running either 3.54s or 4.10s.

Final drive ratio of his setup is ~181:1 in 1st gear /low/low. Final drive of my 2001 CTD is ~53:1 in 1st/low.

 

[Hoooper]

You are terrible at math. A doubler with a 231/300 does NOT equal 4:1.

Start with 300 ft lbs at the flywheel.

1st gear in that transmission is 5.61:1.

Multiply by the low range of the first t-case 2.72:1.

Multiply THAT by the low range of the second t-case 2.62:1.

That's the output to the axles. Nevermind the fact he's running 4.56s and most new light duty diesel pickups are running either 3.54s or 4.10s.

Final drive ratio of his setup is ~181:1 in 1st gear /low/low. Final drive of my 2001 CTD is ~53:1 in 1st/low.

Its not final drive that matters. If youre talking about the affect on the gears, its the torque multiplication up the the pinion that matters. So you would have 39.69:1 at the pinion and 300 ft.lbs flywheel, versus 14.96:1 at the pinion and 750 ft.lbs flywheel. Thats gives him 2.65x more gearing to the pinion and the diesel is 2.5x more tq to the pinion. Looks comparable to me.

Your also comparing modified to stock, if you wish to consider that guys are pushing over 1000 ft lbs then feel free to run the math again.

 

[MoparManiac]

Its not final drive that matters. If youre talking about the affect on the gears, its the torque multiplication up the the pinion that matters. So you would have 39.69:1 at the pinion and 300 ft.lbs flywheel, versus 14.96:1 at the pinion and 750 ft.lbs flywheel. Thats gives him 2.65x more gearing to the pinion and the diesel is 2.5x more tq to the pinion. Looks comparable to me.

Your also comparing modified to stock, if you wish to consider that guys are pushing over 1000 ft lbs then feel free to run the math again.

So you're telling me a ring gear for a 3.54 gearset versus a ring gear for a 4.56 gearset see the same torque from the pinion? I'm not a mechanical engineer so someone correct me if I'm wrong but I have a feeling they'll see different levels of stress that would probably affect the break in.

The point was not to compare a modified jeep to a stock jeep or anything of that nature. It was comparing what a D60 was designed to handle, versus what RobertK was saying they are subjected to in XJs/MJs. I'm saying they are subjected to somewhat similar loads.

 

[Hoooper]

So you're telling me a ring gear for a 3.54 gearset versus a ring gear for a 4.56 gearset see the same torque from the pinion? I'm not a mechanical engineer so someone correct me if I'm wrong but I have a feeling they'll see different levels of stress that would probably affect the break in.

different levels, probably. Which sees more I cant really say. but not much of a difference. If anything, the 3.54 should have more stress on it as the pinion gear is a larger diameter, which puts more TQ into whatever its driving

The point was not to compare a modified jeep to a stock jeep or anything of that nature. It was comparing what a D60 was designed to handle, versus what RobertK was saying they are subjected to in XJs/MJs. I'm saying they are subjected to somewhat similar loads.

I'm pretty sure Chris (vetteboys) rig weighs as much as a fullsize and puts down way more torque.

:laugh:

similar...or way more, I get it confused sometimes too

 

[MoparManiac]

different levels, probably. Which sees more I cant really say. but not much of a difference. If anything, the 3.54 should have more stress on it as the pinion gear is a larger diameter, which puts more TQ into whatever its driving





similar...or way more, I get it confused sometimes too

Um...the whole reason for the lower gear is to get more torque to the ground so the 4.56 ring gear is going to see the same stress concentrated in a smaller area.

Yes Chris's XJ PUTS DOWN way more torque. His final drive is three times that of any new truck.

I said similar loads because we don't tow anything with our XJs, but we do get them bound up in the rocks with significantly more torque.

Goddamn you suck at reading comprehension.

 

[Hoooper]

Um...the whole reason for the lower gear is to get more torque to the ground so the 4.56 ring gear is going to see the same stress concentrated in a smaller area.

The pinion will see more stress, the ring gear less overall.

Yes Chris's XJ PUTS DOWN way more torque. His final drive is three times that of any new truck.

I said similar loads because we don't tow anything with our XJs, but we do get them bound up in the rocks with significantly more torque.

Goddamn you suck at reading comprehension.

I'm saying they are subjected to somewhat similar loads.

you said similar loads because I showed you that you were wrong in thinking he was putting it under way more load

Take a minute, think about what youve done, realize that you were suggesting that 5250 jeep puts a lot more stress on the r&p than the truck, realize again that you were wrong, and get over it. its not a big deal, most are wrong a couple times a day.

 

[MoparManiac]

The pinion will see more stress, the ring gear less overall.






you said similar loads because I showed you that you were wrong in thinking he was putting it under way more load

Take a minute, think about what youve done, realize that you were suggesting that 5250 jeep puts a lot more stress on the r&p than the truck, realize again that you were wrong, and get over it. its not a big deal, most are wrong a couple times a day.

Um...the pinion doesn't see more stress. Please explain that one, because I MUST be missing something.

I said similiar loads because yes, towing 15,000 lbs is one thing, but having a tire bound up in a rock on 38"+tires with 181:1 final drive and 300 lb ft at the flywheel is, IMO, going to put more stress on the axle. I never changed my opinion.

You're getting WAY off base now.

 

[Hoooper]

Um...the pinion doesn't see more stress. Please explain that one, because I MUST be missing something.

no sure. but at the same time I am. Compare the number of 4.88 pinion failures to the number of 3.55 pinion failures in D30s

I said similiar loads because yes, towing 15,000 lbs is one thing, but having a tire bound up in a rock on 38"+tires with 181:1 final drive and 300 lb ft at the flywheel is, IMO, going to put more stress on the axle. I never changed my opinion.

you just changed it, right in that sentence right there

anyway. I have learned one thing in this little festival. (actually I guess I already knew but I just remembered) Never argue with an idiot. they will drag you down to their level and then beat you with experience. so I guess I am losing and am out

 

[NattyBoh]

Wtf Sid you guys do to my thread ... should've taken this elsewhere.

 

[jasonsxj]

do the break in .....then......drive it like you stole it ..........

 

[olysteve]

^this^

 

[MoparManiac]

no sure. but at the same time I am. Compare the number of 4.88 pinion failures to the number of 3.55 pinion failures in D30s



you just changed it, right in that sentence right there

anyway. I have learned one thing in this little festival. (actually I guess I already knew but I just remembered) Never argue with an idiot. they will drag you down to their level and then beat you with experience. so I guess I am losing and am out

It's the ring gear that breaks. I would know because I had a 4.88 gearset along with several of my friends that broke them.

Similar does not mean EXACTLY THE SAME. Goddamnit man. I just said the XJ puts more stress on it IMO.

To the OP, I gave my $.02 when I said that you should ask the guy who geared your axles since he probably gave you a warranty.

 

[vetteboy]

Well no matter what a few people, that have no position or qualifications in this matter, say.

I am amazed at how many people here are so much more, qualified in gears then any of the gear companys, when it comes to gears...

What else are all you more qualified at, then the engineers and R&D personel of companies that produce parts? I sure would like more insight as to correct methods and means, I mean you all should open your own companies. You seem so much more intellegent and qualified then the ya-whose running them now...

You are making some pretty baseless assumptions here...just sayin'. :shhh:

I said similiar loads because yes, towing 15,000 lbs is one thing, but having a tire bound up in a rock on 38"+tires with 181:1 final drive and 300 lb ft at the flywheel is, IMO, going to put more stress on the axle. I never changed my opinion.

I love you man, but if you think anything short of a balls-out pulling truck develops close to maximum torque in 1st gear low range, you're a little misguided. Number one, you'll break shafts far before building that much torque (in that 181:1 low range I snap 35-spline 4340 front stubs all day long just off idle if it gets bound up, which takes roughly 1800 ft-lbs at that tire), and number two, if you don't break a shaft, you're just gonna start spinning the tires.

So traction & axle shafts being the limiting factor, I'm not really pushing the ring & pinion much harder than their OEM applications were designed for.

I'll also throw out there that the D30/35 failures are more likely due to carrier/housing deflection screwing up the contact patch rather than ultimate failure of the gear teeth themselves.

 

[jeeperjohn]

Hey jeeperjohn you know you can multi-quote right?

Quit trying to confuse me with all that fancy stuff. Damn kids!

 

[Bryan C.]

here's my take for what its worth....as someone who has set at least a few dozen r&p's.....

hopefully this will end the debate:

Break-in period for new R&P?

It couldn't hurt, and it might help.

Way to go out on a limb with that statement. :laugh2:


I guess my problem with all of this is the OP being scared about driving his rig home after having the gears installed. The amount of over hyped mis-information being passed off as gospel is disturbing.

Going easy on the gears for the first few hundred miles and changing the gear oil is a reasonable thing to do, and I would recommend that. This whole 20 min driving to reach some unknown optimal temperature to properly break in the gears is a crock of shit. Like vetteboy pointed out, this 20 min thing is far too open ended for me to take it seriously. 20 mins of what type of driving. What if I live at the top of a big hill that takes me 20 mins to drive up, or I am stuck in traffic for 20 mins. Again, way too open ended. Even if you set some standards for the drive, what is this optimal temperature the gears are supposed to reach? What if I drive for 21 minutes because the next exit is a few miles away and I don't want to sit on the shoulder of the freeway?

My original opposition to this thread is that even if you don't break the gears in so-called "correct" internet way there is no way to look at the gears and know the difference. Sounds more like a loop hole for unskilled gear installers to get out of any type of warranty on their installation.

So how do I break in gears? I take the vehicle for approximately a 5 mile drive. In that 5 miles I drive on both the freeway and in town. First thing to do is a few full throttle launches to make sure all the bearing cups are properly seated in the housing, loud noises will happen if not. Once thats is OK, I check for noise on coastdown from 65 to around 35, and then I try to drive steadily at 35, 45, 55, and 65, while listening for any type of gear whine.

As a flat rate Dealership tech I don't have the time to go for a 20 minute road test. And the factory will not pay me to break in the gears on a 20 minute road test. Not one single training class I have attended over the last 20 years has indicated any type special procedures to break in the gear set. I have to personally stand behind my work for 12 months or 12,000 miles. Much longer than any of the garage based gear installers or wanna-be off-road shops. I have set-up literally hundreds of differentials. Haven't have a gear break in problem once, not once. You be the judge of who is more qualified to give advice.

 

[jeeperjohn]

Way to go out on a limb with that statement. :laugh2:


I guess my problem with all of this is the OP being scared about driving his rig home after having the gears installed. The amount of over hyped mis-information being passed off as gospel is disturbing.

Going easy on the gears for the first few hundred miles and changing the gear oil is a reasonable thing to do, and I would recommend that. This whole 20 min driving to reach some unknown optimal temperature to properly break in the gears is a crock of shit. Like vetteboy pointed out, this 20 min thing is far too open ended for me to take it seriously. 20 mins of what type of driving. What if I live at the top of a big hill that takes me 20 mins to drive up, or I am stuck in traffic for 20 mins. Again, way too open ended. Even if you set some standards for the drive, what is this optimal temperature the gears are supposed to reach? What if I drive for 21 minutes because the next exit is a few miles away and I don't want to sit on the shoulder of the freeway?

My original opposition to this thread is that even if you don't break the gears in so-called "correct" internet way there is no way to look at the gears and know the difference. Sounds more like a loop hole for unskilled gear installers to get out of any type of warranty on their installation.

So how do I break in gears? I take the vehicle for approximately a 5 mile drive. In that 5 miles I drive on both the freeway and in town. First thing to do is a few full throttle launches to make sure all the bearing cups are properly seated in the housing, loud noises will happen if not. Once thats is OK, I check for noise on coastdown from 65 to around 35, and then I try to drive steadily at 35, 45, 55, and 65, while listening for any type of gear whine.

As a flat rate Dealership tech I don't have the time to go for a 20 minute road test. And the factory will not pay me to break in the gears on a 20 minute road test. Not one single training class I have attended over the last 20 years has indicated any type special procedures to break in the gear set. I have to personally stand behind my work for 12 months or 12,000 miles. Much longer than any of the garage based gear installers or wanna-be off-road shops. I have set-up literally hundreds of differentials. Haven't have a gear break in problem once, not once. You be the judge of who is more qualified to give advice.

OK, the 20 minute thing is a limit to keep the gears from getting too hot under normal driving conditions. This means no hard throttle launches or climbing super steep hills. The enemy of gear longevity is excessive heat. If you have to drive up a steep hill to get home stop after 10 minutes and let the diff cool off. The whole point of the break in is to prevent the gears from overheating. It is very simple. This doesn't mean the gears won't possibly be OK with no special break in but if I put out the money for new gears you can bet I will do everything I can to protect my investment.

 

[Bryan C.]

OK, the 20 minute thing is a limit to keep the gears from getting too hot under normal driving conditions. This means no hard throttle launches or climbing super steep hills. The enemy of gear longevity is excessive heat. If you have to drive up a steep hill to get home stop after 10 minutes and let the diff cool off. The whole point of the break in is to prevent the gears from overheating. It is very simple. This doesn't mean the gears won't possibly be OK with no special break in but if I put out the money for new gears you can bet I will do everything I can to protect my investment.

More scare tactics, great. :sure:

 

[garr]

This is Just my un-professional observation!

If you are swapping gears do a little comparison for yourself as I did,
drive your rig hard before the swap & feel the diff cover, I will probably be warm; after the new gears are installed drive it normally for 20min & feel the diff cover, But be very careful as the cover will be HOT! so it seems there is some breaking in going on during the inital drive on new gears.

And for those that say new vehicles require no gear break in, You are correct, But if you have the opportunity do a side by side comparison of any make aftermarket R&P with a NIB factory R&P, You will notice that the factory R&P is finished much better.

Remember just my un-professional observations!

 

[dart70LA]

It is undeniable that heat breaks down oil. New gears create a lot of heat. And it is possible that this could result in damage/failure. Just because you have not experienced failure first hand doesn't mean you should ignore the recomendations of the engineers and experts who developed/manufactured the product. It doesn't make sense to me to spend this much time/money to re-gear and then be so impatient as to not be willing to wait half an hour after twenty minutes of driving.


Bryan C.: I wonder if you ever timed your 5 mile break in procedure. Would it work out to be roughly 15-25 minutes, and then a cool down period before the customer picks up the vehicle?

Everyone else: Have you ever seen a new vehicle on a dealers lot with less than 7 miles on the odometer? They all get a quality shakedown run around a track(may only be a line painted around the factory parking lot with a few rumble strips etc....). Probably put 3-5 miles on before it gets on the train or truck.

The manufactures/gear sellers all have the same basic break in procedures:

Precision Gear:
http://www.precisiongear.com/pgtechbreak.htm

Randy's Ring & Pinion:
http://www.ringpinion.com/ContentFr...t/Parts/RingAndPinions//New_Gear_Break-In.inc

From Superior FAQ: Half way down
http://www.superioraxlegear.com/faq.php

From Yukon: see page 18
http://www.yukongear.com/Downloads/Technical_Help/Installation_Kit_Instructions.pdf