Contact Patch & Pinion Depth Explained

Differential Contact Patch & Pinion Depth Explained

[@twotwentyswift]

If only all videos were this clear, concise, and well done. The old saying is "A picture's worth a thousand words" and this animation is worth a lot more than that. Fantastic job DLMaster!

[@petersipp5247]

This is then best vid on showing how to make diff adjustments. Thank you ! I have wondered for years about this!

[@pashafixesthings]

Hands down, the BEST video on YT explaining the principles of diff adjustments. In 7 minutes and 16 seconds this man achieved what others couldn't achieve in hours of screen time!!!

[@DrivelineMaster]

Thanks, My goal is Short, sweet and too the point with quality video and audio.

[@cruz1742]

I don’t get it!! He change the adjustment and return to 10 and got different backlash!!!!!

[@DrivelineMaster]

I changed the depth adjustment which changed the backlash. I reset the backlash to .010" and retested the contact patch which moved slightly. What don't you get? I'm willing to explain it.

[@jdwisdom9433]

This s a subject I've always wanted more about. Thank You for the clear, no music explanation. JD

[@ibraimopestamgy8298]

best explaining video on youtube until now !!!!

[@markw3981]

Agreed, best demonstration of pinion depth and backlash I’ve seen. Thank you

[@oculophilia8724]

Masterclass. Like a video game from the 90s you subtly explained the vocab needed to win

[@djbenhur4068]

perfect this is what i call a mechanical service well done congratulations

[@petejoseph8257]

Finally, someone giving perfect explanation to pinion depth on a 9 inch style diff. Thank you.

[@DrivelineMaster]

This really applies to all differential designs however the 9" style was much easier to make an adjustable pinion to demonstrate the effects pinion depth has on a contact patch.

[@dobrzpe]

what a GREAT explanation of what's going on with the gears - ESPECIALLY with the visual aid! thank you!

[@millerrich100]

Iv never rebuilt a rear differential before but I’m going to have to rebuild the rear differential in my 96 Ranger Splash. This video helps me a lot and gives me the confidence that I can do it! Thank you!

[@DrivelineMaster]

Glad I could be of help. Don't hesitate to reach out if you need additional info or help.

[@patricklydon6935]

Putting gears in a friend's Jeep. Set this video to him so he can better understand what I'm doing. To the point and clear explanation! Thanks

[@dongkyukim3580]

this is the best video i’ve seen on youtube explaining how all this works in great detail!

[@dianpurbonugroho3086]

Pretty clear and educative. I have learnt 2 ways of differential gear adjustment from you, i.e using dial gauge measurement and contact marker visual inspection. Thanks!!

[@tjhessmon4327]

The Dial indicator is measuring Ring to Pinion gear backlash (clearance) The gear contact paste, is indicating Pinion gear engagement depth with the ring gear. Two very different measurements... What you are not told is in order to setup a pinion on an 8.8 Ford, it requires the purchase of an extra (setup) bearing, identical in manufacturer to the bearing you will finally use. This bearing must be modified to "slip fit" on to the pinion so pinion depth can be setup. Additionally, you will need a few extra crush sleeves for this process...

[@moparnut6286]

Alway well explained and illustrated! Love this channel!

[@winki51z]

I overhauled a lot of differentials in the past; and your video hits the mark. Most people don't understand how precise the set-up has to be; and how a very very small miscalculation can cause all types of drivability issues.

[@DrivelineMaster]

Thanks

[@DL101ca]

Should emphasize the fact that contact patch and backlash should be checked with the axles in the differential (loaded) and tires on to offer some resistance in drive and coast.

[@DrivelineMaster]

Thank you for your comment and observation. The axles do not have to be in and in this removable design that is really difficult. It is very important to provide a load or resistance to rotation to obtain a good contact patch pattern. What you can't see so well is I built in a braking mechanism that is applying rotational resistance to the ring gear. This is adding enough load to provide a good pattern. The objective of this video was not to show how to perform a contact patch pattern but instead to explain how the pattern is effected by the change in drive pinion depth.

[@robertclymer6948]

Nice! Wish my Ford 9" pinion was that easy to adjust, but I get the concept totally. Thank you.

[@Steel6Strings]

Fantastic information. Just what I was looking for!

[@joeasbury974]

Excellent demonstration! Thanks you!

[@JG-kv4oi]

Thankyou! And shown with a 9" diff too, my fave 🙂 Doesn't get better than that!

[@barsanyibela4027]

This is a very clear and useful explanation of an important topic. I'm really happy that you published this piece. Thanks.

[@Limeayy]

WOOHOO more information differentials :D Loving it, keep up the great work DrivelineMaster! Visual is always nice!

[@vdavis1959]

I'm no mechanic and I....... even got an understanding of the process. The best explanation I've seen yet.

[@DrivelineMaster]

:)

[@billbled]

great explanation - and a BIG thank you for NO background music. I hate it when presenters do that.

[@burtvincent1278]

Good information. I've had production experience setting up construction equipment spiral bevel gears, same system applies. A little toe bearing centered up is acceptable as opposed to heel bearing. The toe of the ring tooth being thinner will flex and spread increaseing the load bearing pad back towards the heel.

[@DrivelineMaster]

You are correct.

[@tjhessmon4327]

Excellent video explaining Ring and Pinion gear relationship. The most helpful to me was the use of gear contact paste on just two teeth. I see other videos where its slopped all over the entire ring gear. Your approach makes better sense.

[@DrivelineMaster]

My factory training taught me to paste every tooth and it can revel some information about the setup however in real life I paste 4 teeth every 90 degrees. This gives me a feel for the setup.

[@meradu2]

Thank you for your knowledge and you willing to share this information 👍 Have a bless day

[@aerialrescuesolutions3277]

Excellent video. Very well shown and edited, short and awesome. Thank you, Jim H.

[@DrivelineMaster]

I try to do this with all my videos.

[@robertpc100]

Great explanation on set up.very good explanation.

[@aros007z]

Great instructional video, thank you!

[@DrivelineMaster]

Your Welcome

[@alinhinthoulay6323]

Awesome video. Great for ASE prep

[@BoostedBlazer]

Thanks for the clear info!! My 12 bolt thanks you!

[@ChrisWilliams-pu8pj]

Very nice presentation making process understandable. Thank you!

[@byuiautomotivevideos2254]

This is a great explanation. My students will benefit from this as well. Thank you again. I enjoyed your presentation at ATRA this past October.

[@DrivelineMaster]

Thank you stay safe and healthy

[@charlierichardson1826]

Awesome! Thank you for video.

[@highdownmartin]

Very clear. Very useful. Many thanks!!

[@jockellis]

Thanks. I do NDT in a shop that repairs speed reducers but don’t know much about their operation. So this is what the assemblers are doing when they have a gear set together but keep tinkering with it.

[@DrivelineMaster]

Most likely.

[@ovalwingnut]

I tried your suggestion with that "straddle mount" during a third date. It didn't go well. And I assure you my pinion shaft was large enough even though my date didn't think so. Just saying. But thank you for the video. It was worth a try. You RoCk!

[@tilapiakiller3123]

Best vid yet 👍

[@johnnygregg1550]

Love this video! Very good information!

[@DrivelineMaster]

I'm glad. My goal is quality training video's.

[@3zawaze]

Amazing Bravooo

[@Parker_Garage]

Liked the video before I even watched, knew it was going to be helpful based off the thumbnail

[@Dwolfson22]

Great video!

[@diepnguyen4734]

very good video training ,clear explained easy to understand ,thanks

[@GroovesAndLands]

Perfect explanation and demonstration. A+

[@stylerunner2959]

Finally I can understand this.. reading from a book just doesn't make sense in my head. Thanks for the visual!

[@DrivelineMaster]

Glad this helped

[@J.PROJECTZ]

It looks like I Finally understood the assignment after watching this video, thanks C ñor 😊

[@SierraMike78]

This is stellar, "DrivelineMaster", obviously.

[@r.l.mashburn5246]

Great Video.. No music thanks.. just great information..

[@olivedrabgarage6243]

So what were you adjusting everytime you had to move the backlash back to 10 thousands ? How do you read the number on the pinion gear to determine what shim pack is best and closest to start with? If it's a minus number foes that mean you need to add shims to bring it forward to the ring gear or have less shims to move it down to that measurement from the centreline?

[@jesusglopez8430]

Excellent very educative and informative thanks.

[@FaithRisen]

Thanks for the video!

[@quick65filly]

Excellent explanation. Hard to get better than this.

[@alibehboudi]

amazing video.so thanks. do u have video about adjust preload of bearing of penion ?

[@tdmjason]

Wish all differentials used this adjustment features. Way easier to set up. Modern truck differentials aren't this way at all on adjusting easily.

[@peterfuchs7822]

Great Video very informative thanks

[@jt496]

Thanks great vid

[@Coolhand99au]

Excellent video Thanks

[@Gonecheenin]

I'd like to see you continue moving the pinion away from the ring or "increasing the pinion depth" until the pattern went unacceptable the other way. I just set up my Toyota 8" and the drive pattern you found acceptable I had at one point, but when I read the pinion teeth it was showing a shallow mesh leaning towards the diff centerline or toe (this is a rockcrawler) - so I pulled another .010" from the pinion head stack and ended up with a nicely centered oval drive & centered comet tail pinion pattern - but my coast pattern still looks similar to your drive pattern and I'm not sure why.

[@DrivelineMaster]

Your drive side pattern is your most important and the biggest goal is to make sure the pattern is not running off the toe, heel, face or too deep into the flank. It would be great if drive and cost would always both be perfectly centered but that is rare. In fact I prefer the drive side to be slightly towards the toe and coast to be slightly towards the heel. I do this because under heavy load the pinion will thrust slightly towards the front of the vehicle causing the drive and coast side patterns to center. If you are working on a front diff and it's flipped so the pinion centerline is above the axle like front diff's on 4x4's offend are for ground clearance the drive and coast sides of the ring gear are reversed. The drive side is concave and the cost side is convex. I hope this helps.

[@joefw2446]

Excellent!... much thanks.

[@clintlewis1719]

Gotta love the Ford 9"

[@warrenzevonsangryghost6055]

God yes...I've got a Dana 44 I need to do and I'm dreading it.

[@ibraimopestamgy8298]

congrats !!!!

[@GearsandCrosses]

Thanks so much for the video! It really made it clear for me. I was wondering if a used rear axle was making noise from say too much back lash, could it be made quiet again by making the right adjustments to the back lash/wear pattern? Or would you have to rebuild the rear end and get a new gear set? The rear axle has 120,000 miles on it and the teeth on the gear do not "look" bad.

[@DrivelineMaster]

If you are getting clucking from too much backlash especially when switching from D - R or R to D you most certainly can change the backlash adjusters (Shims or Threaded Adjusters) to correct or reset the backlash. You won't need to mess with pinion depth and you should not have to worry about contact patch. As long as you have the dial indicator and the tools and methods to make the adjustment. Just make sure to check your backlash in at least 6 to 8 different locations around the ring gear and make sure the backlash is never smaller than the minimum specification. If your getting humming or moaning noises that is not a backlash noise and readjusting the Backlash will not fix this type of noise.

[@GearsandCrosses]

@@DrivelineMaster the noise I am getting is a moaning noise from about 30 mph on up. It moans when I am on the gas. If I let off the gas and coast it gets a lot quieter. I changed both rear axle bearings as on side was bad. I didn't see any play in the pinion bearing and it spun freely. There were no visual defects in either gear. What do you think is the cause? Thanks in advance

[@DrivelineMaster]

This is a description of a classic rear drive pinion bearing noise. Sometimes worn gears will do this but it's not as common as a pinion bearing. Normally if it's gear noise you can't see the wear but a contact patch can sometime identify worn gears. The contact patch should be non symmetrical triangular or oval. Normally if the gears a bad the contact patch will be a straight thin line. Place a listening device such as a mechanics stethoscope or you can use a screw driver or extension bar up to your ear while holding the other end against the differential housing in different locations. Once near the rear pinion bearing and once near the front pinion bearing. Do this with the wheels off the ground and someone driving the vehicle accelerating and decelerating as you listen. I put 95% chance your problem is the rear pinion bearing even if rotation feels smooth when turning it by hand.

[@GearsandCrosses]

@@DrivelineMaster Thank you for your detailed advice!!!!!

[@IndianTruckWorkshop]

Great sir very informative 👍

[@blessedhellride2615]

Exellent learning tool!!

[@farerse]

this video doubles as a relaxation / sleep video!

[@DrivelineMaster]

Well......... if your not interested no one is forcing you to watch.

[@farerse]

@@DrivelineMaster actually it was a compliment, very relaxing voice!

[@DrivelineMaster]

Sorry for the reaction. I thought I was boring you.

[@bigears4426]

Nice and clear to understand , thanks

[@linda3n977]

sehat selalu master.. terimakasih ilmunya

[@georgec7798]

This video is great and helps a lot. The only thing I don't understand is when you say you have to move the pinion gear father away from centerline, I don't know which way you're moving it because I can't see it moving in the video.

[@DrivelineMaster]

Watch from timestamp 0:26 to 0:31 and 1:16 and 1:22. The pinion moves to the left but I don't like to say to the left because what would happen if the image was flipped 180 degrees or even just 90 degrees. So it's not a good idea so say the pinion moves left, right, up or down but instead talk about in relationship to the centerline of the ring gear.

[@georgec7798]

@@DrivelineMaster I'll try to look again, maybe I can watch the video on a 65 inch TV. Thank you

[@DrivelineMaster]

might be hard to see on a phone with a small screen but any monitor larger than 13 inches should be large enough to see the movement.

[@abdulhassan1107]

Subscribed, after watching this masterpiece

[@danielebbeling4056]

Very clear video in showing relative positioning and optimal settings checks. Could this test determine if a used pinion gear/ring gear combination , has been worn beyond suitability for reinstallation practicality ?

[@DrivelineMaster]

severely worn ring and pinion sets are normally noticeable by visual inspection however they will often exhibit patterns that look like thin lines as compared to oval or triangular shaped.

[@danielebbeling4056]

DrivelineMaster Thank you for your reply! I will bring this ; and use it. Teach it;also.

[@johnpower8356]

Great video, never seen that paste I use blu

[@robinferguson5975]

Wow this is a great video thanks

[@davidjunior3125]

Nice explanation mate. Thankyou

[@DrivelineMaster]

Thanks

[@bigbothoee8617]

Nice vid explains a lot I have a better understanding of contact patch but what happens if one side is ok but the over drive side (back side is off ) how would the adjustment be made ?

[@DrivelineMaster]

The drive side of the ring gear tooth is always the pattern of most concern. If the coast side is off a bit I don't worry too much as long as the drive side is where I want it. Two other factors effect contact patch. Backlash and worn gears. Although Backlash effects the pattern differently (hey, that give me an idea on a new video) worn gears will create all kinds of weird patterns that won't make any sense.

[@AmazingTechnology1]

Nice job Friend

[@dinosworkshop6870]

Very good and helpful video

[@ImpalamansGarage]

Thank you!

[@zourdiesel8579]

Great info

[@jeffkleinow433]

great video

[@mattleggett5609]

Are these gears face hobbed or face milled? Also does that actually even matter when checking patterns? I've been trying to learn all I can when it comes to setting rears up, love this demonstration!!

[@DrivelineMaster]

I believe this is a face milled Five-cut gear set. If you have been doing some research then you most likely found this URL. gearsolutions.com/features/face-off-face-hobbing-vs-face-milling/ also this from Yukon gear www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwif_e-JxbL0AhXloFsKHYN6DQ0QFnoECAIQAQ&url=https%3A%2F%2Fwww.yukongear.com%2Fweb_images%2Fpages%2FBrochures%2F2-Step-vs-5-Step-Gears.pdf&usg=AOvVaw2q8lfMkwNzdKq7Hzfd8FJ-. The pattern is different and moves across the tooth differently depending on how it's cut.

[@miguelmichael7056]

Couldn't be any better

[@georgewashington938]

good presentation

[@911engineguy]

Well explained.. now please come and setup my 911 gearbox :)

[@phumlanimchunu8670]

Nice video...

[@lindungsitanggang3354]

Good yes the best informition

[@narcisoveloz2102]

Excellent.

[@stevewalther2293]

This explains everything.

[@DrivelineMaster]

Thank you. That is what I was going for.

[@salmanalaalinew]

Excellent vedio

[@frankpaya690]

I like the way this video got right to the point . I'm going to Delete some of my other videos that are too long-winded.

[@DrivelineMaster]

Thank you for noticing. That is one of my goals along with; Short, clear, informative, accurate and quality.

[@minkodima]

Thanks!

[@josepeixoto3384]

Subscribed; You are the Master, great explanation; just out of curiosity what would it take to get a perfect pattern on both sides,and is it possible? and any advantage to doing that,just for (heavy,towing etc ) street use?

[@DrivelineMaster]

It does happen but not as often is I would like. Start with a case with zero axial run out. Add a quality gear set with tight tolerances. Have it assembled by someone who takes a lot of care and attention to details. Finally the proper pinion depth. I don't think the perfect pattern is that critical. I personally like the drive side a little towards the toe and the coast side a little towards the heel when I take my pattern.

[@josepeixoto3384]

@@DrivelineMaster Thanks.

[@jackkallemdjian3945]

One thing that needs to done is to put the crown wheel under some load a crow bar forcing down on the wheel between the case and coat 6/7 teeth with paste and turn the pinion twenty plus times that will give a real good marking and a bit less paste, engineers blue can be used for marking too,

[@DrivelineMaster]

One thing that I forgot to show was that I did do that. I formulated a section of brake pad onto a bracket with a pressure adjustment screw so the crown gear or ring gear as we call it was under pressure. I just didn't show that because the focus of the video was on what happens to the pattern as the depth is changed.

[@duramax78]

Hi should there be play of about 1/8th of a inch between load and reverse on the piñon.? Tia.

[@DrivelineMaster]

1/8 of an inch is equal to 0.125" and that is excessive. Each differential is different but on an average most differentials will have free play (called backlash) between 0.005" and 0.009". I have see specifications as low as 0.003" and as high as 0.014". Evan at 0.014" that is a large difference to 0.125". It requires a dial indicator like what I used to accurately make this measurement.

[@DL101ca]

Only on an ox cart...

[@mercedesmaintenance.6339]

When you are testing the contact patch (by turning the ring gear) doesn't it have to be under some load? Thanks for the video.

[@DrivelineMaster]

Yes, You are correct. The cut away I used had a friction shoe pressing on the ring gear that you could not see as I turned the pinion. When I do this on the workbench or on the car I rotate the ring gear and apply rotational friction to the pinion. One easy way to do this is to enlist an aid. Wrap a shop rag around the pinion just under the flange. Have the assistant pull on the rag to create rotational friction to the pinion. This can make it impossible to turn the ring gear so the assistant needs to give a little on the force just enough to allow you to turn the ring gear. I hope this made sense. The greater the load the better the contact patch you will get.

[@mercedesmaintenance.6339]

@@DrivelineMaster That makes total sense to me. I really appreciate your help and video. I'm currently restoring a 1970 Mercedes 6.3. As I'm sure you know the rear end of a Mercedes of this era is a little different, but I'm assuming all the principle's you spelled out apply. I may message you from time to time if that's ok:)? Thanks once again for your video. Cheers John.

[@DrivelineMaster]

Yes you can email for advice. The principles are the same. I don't have much vintage Mercedes experience.

[@mercedesmaintenance.6339]

@@DrivelineMaster Thank you very much. I really appreciate that.

[@autophyte]

Very good. but it's not so easy on old jeep Salisbury diffs. To adjust pinion and backlash, you have to remove the guts, and pull off the usually very tight tapered bearings, then add or subtract shims, put the thing back together again, check the contact pattern, and if necessary (usually), pull the whole thing apart again, remove bearings, add or subtract shims..ad nauseum. Thank goodness for the screw in type bearing adjusters.

[@DrivelineMaster]

Yes, there is a bit of trial and error involved and some are harder to do than others. That is why knowing if you add or subtract is important. Nobody wants to go through all that work only to find out that you added when you should have subtracted. If you do this on a frequent or semi-frequent basis I suggest buying a pair of bearings for the diff and use a small cylinder hone to remove a little of the metal from the inside of the inner bearing race so the bearings just slide on with no wiggle room. That way you won't have trouble removing the tapered bearings. After you know which shim produces the correct contact patch replace the modified bearings with new bearings with a tight fit. Save the modified bearings for the next job. PS. Make sure to thoroughly wash the modified bearings after honing and lightly oil them before using them to setup your pinion depth.

[@edfx]

Is it theoretically possible to get correct contact patch with multiple pinon depth combinations? My repair shop told me they adjusted the pinion to new position altought contact patch was correct. I think they are messing with me and there is exactly one combination that is correct.

[@DrivelineMaster]

Some differentials are more sensitive to pinion depth shim change than others. In other words .006" change on one diff won't make much of a difference when on others it will make a huge change. There is a contact patch sweet spot on the drive side of the ring gear tooth that allows for some flexibility as long as the contact patch is not off the edges of the toe or heel or too high on the face or too deep on the flank the pattern is fine. So yes, it is possible to have multiple depths with the correct contact patch. More than likely those depths are within a few thousands of a inch of each other. This is a really small window.

[@zourdiesel8579]

Great

[@mariaessahgella8503]

easy way and technical process

[@callofgeorge]

if the drive is acceptable and the coast is off.. how would you adjust one without throwing the other off?

[@DrivelineMaster]

You can't. Go with the drive side. How far off is the coast. As long as the pattern is not totally running off the toe or heel or too high on the face you should be OK. I'm assuming your backlash is also within specification. If it is really bad make sure you don't have excessive backlash variation or ring gear run-out. If all is good and the patterns are still really far off there is a problem with the gear set even if it is new. I like to set mine so the drive side is a little towards the toe and the coast is a little towards the heel. that way under load they will move slightly towards the middle of the gear tooth. Hope this helps.

[@callofgeorge]

@@DrivelineMaster very helpful info. thanks. it was a hypothetical question. I'm not experiencing the issue, just curious if it was possible to remedy if it occurred. i figured it would be a faulty ring/pinion if it happened though. i'll be assembling mine in the next week or 2.

[@Peter-zm6ln]

@@callofgeorge this is what i am experiencing now in trying to resetup a set of gears in a Dana. My coast and drive pattern are no way the same.