Is Scruffy's Drivetrain Toast? Fixing Leaks and Finding Creaks - Scruffy Build Part 7 

Hey man, so a couple things... First off, you need a magnetic base and dial indicator to measure the backlash at the ring gear (available for cheap online). Depending on the axle, it's usually anywhere from 7-15 thousandths for a used gear set. So can't really tell from the video as the pinion and ring gear are both moving. But seeing those metal shards in there is not encouraging and given the size of some of them, I'd say that gear set and/or the bearings are going out for sure. As far as the wear pattern, no, that's not normal even for 150k miles. I would usually suggest gear marking compound to run a pattern, but in your case, honestly, there's no point to it. That's bad. At a minimum, it looks like the pinion depth is wrong, either from improper installation or shot bearings. It was likely set up properly when it came off the assembly line so unless someone's torn into that axle pretty significantly, it's pointing toward bearings, IMO. The fact that the pinion is wearing the ring gear like that tells me the likely culprit is the pinion bearing(s). It's allowing the pinion to walk forward under load wearing the heel side of the ring gear. Regardless, here's what I think you want to know: The ring/pinion and bearings should all be replaced. Labor is likely ~$400 and parts another $300-400. And I've seen and repaired many a shadetree mechanic's gear install so be very wary of whom you'd choose to do this job. Personally? I'd source a entire replacement rear end. It'll be WAY cheaper that R&Ring the gears/bearings in your current axle and way easier than tackling it yourself as there's definitely a technique to a successful gear swap. If you can source a replacement axle with a limited slip, that's cool, but you can always slap in a lunchbox locker into an open diff for $200-300 and that would definitely be well within your skill set. Any other questions or if you think I can help in any way, hit me up. Good luck!

I like to take a hybrid approach to things like this. Grab a junkyard axle and toss it in there, and you're back on the road quickly. Throw the old axle on jack stands and as you have time an money, tear into it and start a rebuild. You could even re-gear it if you want. Take your time on it, get it right over some months or longer, and then swap it in in a morning. That way you get on the road quick, and you still get your rebuild for the long term :)

Seems like a perfect opportunity to add a locker or limited slip.

The GM S series vehicles trucks, vans, and suvs are known for going through rear ends. I was in pest control for several decades and have had S10 trucks mostly and that has been the most common issue with them. My current S vehicle is a 2004 S10 Blazer 4 door 4x4 and thankfully it hasn't got those issues but it was a Fire chief's rig up around Rathdrum somewhere and had nothing but Amsoil full synthetic products for it's first 200K miles and I have put another 36K miles on it with Mobil 1 products and I can see this rig going over a million miles pretty easily.

I taught myself how to setup gears and rebuild diffs through RU-vid and research. I have worked as a machinist a bit and have some mechanic training and experience. But I’ve never been a professional mechanic. I’ve had great luck with axle rebuilds. From watching your videos I’m pretty sure you can do it too. One thing easy to check is hold the drive shaft securely and then see what the backlash is on the ring gear with a dial indicator (cheap one from harbor freight is fine) and some white out on clean gears can show us your pattern better. I’m happy to help you diagnose more if you want.

Remember if the transmission oil looks that bad triple change it. change fluid and drive 20-100 miles change fluid again then repeat as needed. That helps clear all the nasty oil that is in the torque converter out too. You will never regret posi and it won't affect lash. Do you have a votech near by? They might do the rear diff for parts. A junkyard rear axle could be hit and miss but you can pull the rear cover and decide but don't let the EPA see you.

Just want to say thanks for the content man! This series inspired me to buy my 99 Astro Awd conversion van. I have the same rear end noise in mine as well. If it were me, I'd pull a lower mileage junkyard unit and slap in a lunchbox locker. Keep up the great videos! 👍

Run a heavier oil in the differential. And keep riding it till it blows the spider gears

I bought a junkyard if from the junkyard for a hundred fifty bucks in both of them had the G80 rear locker and they both work great

If you do end up replacing the differential, I would highly recommend a helical diff. Eaton offers a Detroit Truetrac model 912A317 which should fit these Sierras/Astros. This helical diff paired with that New Process 233C you added will make Scruffy even more buffy.

Keep throwing money at it, its so worth the trip

I really love these Astro/Safari 4x4 videos, they're why I subscribed. I want to build one of these but apparently word has got out & they're not affordable anymore. Oh well, maybe I'll spot a deal quick & get lucky. Either way I wanna see how your van build goes!

Ah the headachs and joys of being a second hand owner of a high millage automobile. Still way cheaper then a modern panel van converstion.

Living close to Amsterdam, I learned to never check out the rear of a leaky tranny.

As a master mechanic, I can tell you chunks of metal on the magnet is a very bad sign. Your best option for the cheapest cost is a full junkyard axle, but there is always a risk of getting a bad one. Otherwise, have a professional rebuild the rear end so you know it's right. This is the kind of thing that is very easy to mess up. Good luck! Sorry for the troubles with your diff, I've been there.

I think it'd be hard to find one in a junk yard that has fewer miles on it, but that'll be the best combination of cost and effort. It doesn't take much to swap the ring and pinion, but getting them aligned properly with the shims on either side is a pain; and it wont last long if you don't get it just right.

I'am Your Newest Subscriber Great Videos I Just Got A 1999 Astro Van

I would pull the wheels and check the axle bearings before i did anything with the diff. An axle bearing is pretty common on these.

i use a brass wire wheel in my drill to clean of gasket material from the pan, because it steel and not alum i have never had any issues with it, the metal won't have any issues with that !!! and i always use a thin film of rtv sealer on both sides to make sure no leaking!!!

Absolutely loving this series 🤙 So good.

I think you're looking at rebuilding the rear end due to the pinion gear moving with ring gear immediately like there is no backlash. Could you find another in the junkyard, probably but you need to find one with the same wheel mounting surface width which might be more rare being it is a van and not a truck. If you're going to have a shop rebuild this for you it you may get a cheaper price if you remove the whole axle assembly because they charge different rates for taking up hoist space. Look for a 4x4 offroad or jeep shop. They change out ring and pinions and add lockers all the time. Because they do it so much they have it down to a science.

As someone who does jeep diffs for a living, finding metal is not a good sign. Willing to bet pinion bearings are loose/worn and causing pinion to back away from ring gear causing that wear. It takes some specialty tools to build a diff properly(Dial Indicator, torque-o-meter to get pinion torque to rotate right) but inst impossible to do yourself in your driveway. Another lower cost option then having someone rebuild it would be to find a lower mile junkyard axle assembly and most places will let you open the cover before you buy it to check, just make sure the gear ration is the same. If you want to tackle it yourself I can send you all the specs and measurements you will need.

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Just fixed my crankshaft seal leak and now she's running perfect

Getting a used full axle from a van with less miles could make sense financially

Probably your best bet is to swap in a salvage rear axle assembly from a wreck and go ahead and do the Journeys 4x4 transfer case swap while you're at it so that you can roll in 2 Hi on dry pavement. The reason the rear diffs go out on these Astros is running the AWD with uneven wear on the tires ( or different sized tires). I ran into this same problem on my 2004 with rear disks, the axle for which is hard to find and sort of pricey. The rear axle will be easier to find and cheaper on yours with rear drums. You might have to put in new outboard axle seals on a salvage unit, which is not a big deal. You just don't want to mess with the pinion seal which would involve resetting the pinion depth, backlash, etc. Very tricky to do correctly.

Setting up gear lash in those is such a pain, ive found its easier to get an entire axle from the junkyard thats in better condition than the one you have now. If you're lucky you'll find one with limited slip anyways. Make sure the gear ratio is the same by checking RPO codes in the glovebox, or i believe they stamp the ratio in the ring gear itself. Get new wheel bearings into your new (to you) axle while you're at it, and SEND

all i know is my 2002 astro glides down the freeway at 80 and 90 but also takes off like a little cheyenne too.. so thats probably your rear end being my astro has 289k miles. keep on we Love Scruffy

I had a similar issues like this before. It was one of the bearings that held the ring gear and its assembly in place. I was able to pull the axles then get whole ring gear assembly pulled out. After that, I found a shop that had the replacement bearing and they were able to press it on for me. In all, it was about $200 for me. You just have to be careful and keep a eye on where the spacers are because when you put it back in, if there in the wrong place, the ring and pinion gear will be out of alignment.

dope, i'm replacing my pan with one with a drain plug. I haul a lot so it's worth it

I change out the rear end on Mine by myself first time I tried it

I'm subscribing right now to your channel

Great video thank you for your hard work

What John Booth said below is good to do. Even though you changed the filter the balance of the oil in the trans has dirt and small metal filings in it. After a certain amount of driving, your choice, a thousand or more change oil and filter again. The trans should be a 4L60 and has a valve module exposed when you drop the pan. If it is shifting hard or jumping during shifting that valve body could be dirty. A filter change does not clean it but it is easy to pull the connector and drop the module to clean the screens or it is inexpensive enough to just replace. You can do the rear end yourself not hard just study up and take you time.

That’s a bummer. Hopefully your comment section will pull through on a cheap fix. 🤘

Fun fact.... I was at the valley pull and save Monday and there was 1 astro/safari there that had a g80 rearend!

New [bearings] on pinion shaft and seal from what I could see. A junk yard rear end is also worn the pinion gear lash is set to the ring gear. So if you swap parts you will have to reset that lash not easy. There is a crush spacer on the pinion to set lash, it's hard to hold the pinion and tighten the outside nut to set lash good luck and may the force be with you!!!!! I have done several.

Be sure to double-check the torque in a week or 2. Heard stories where people forgot to and the pan falls of or the fluid leaks out

I'd go to the wrecking yard that you got the transfer case from and pull the covers off the diffs on the vans there. Maybe start with the one that the transfer case came from if it's still there. I'd take note of magnets in the diff covers and find one that had nice looking gears and no metal shards on the magnet. I had a 1960 Falcon that was a bit noisy in the diff, I changed the wheel bearings and it ran silently. That diff was about 35 years old back then and I doubt anybody would have done a rebuild on it previously. My van is all fitted out in the back and it's amazing how quiet it is in the back now, no road noise at all. Good luck Man!

No mechanic but had a great time watching :D

You can see the pinion rocking around, the problem is most likely the pinion bearing. I have a similar amount of play in the rear of my Astro, but no noise or vibrations yet. It wouldn't be much to have that swapped out and try using a heavier weight gear oil.

The gm 7.625 rear end is notoriously weak. I have had two blow up/get loud. I cracked a spider gear in half at the axle splines on the first one too

Yessssssss more van stuffff!!!!!!!🤟🏼😂

Love this scruffy series

I got to tell you man if your in love with the van invest in it. Money comes and goes and life is short. Im in the same boat with my build. I love it and will be investing in it till i cant anymore.

Bits of metal look like carrier assembly spacer or crush/thrust washer, yep needs a complete rebuild for sure! is a fairly straight forward job but you will need a dial indication micrometer with magnetic base,a good fish scale or draw scale for proper draw/drag tourque on that pinion some pattern paint and most specs come with a decent ring and pinion set.I'd just grab a princess auto dial indicator and check a few diffs out at the wrecker for backlash and go from there, probly easiest rout to go with.Great vids by the way!

Dude you two can do it! positive thinking and parts YOU GOT IT!

Looking at that transmission oil, it's not ideal but if it gives you any comfort, my new van also had black oil. Replaced the oil a few times until it was the right colour and the box is still fine. When the oil smells burnt is when you start running into issues.

Great video. All the best with the repairs.

I believe I had that noise and drove it for around a month, starts to shake a bit too. Worse under low engine speed or big loads - trailer or hard accelerating - I believe it was a rear universal or some bearing on the end of the driveshaft. Possibly the pinion bearing.

I think the bearings for the pinion are shot causing it to basically drop or have more play than intended causing the mating angle to go wacko causing the wear you saw Pinion also looks nicely discoloured from getting hot

no idea about how this stuff works but a cool set of videos so far

The parts to rebuild it cost about the same as the labor. If it’s your first rebuild and you go DIY, pull the whole rear end out and set it on jack stands pinion snout pointed down. If you want to pay to have it done, contact the local jeep club and see who they recommend for gear setup. I would also recommend doing all the bearings in the axle. You have to pull the axles out anyway so might as well while you are in there.

I have a 2003 2wd astro it has a drain bolt for the tranny pan lucky me

Get a junkyard diff. You may get lucky and get one w a limited slip. If not, it’s a good opportunity to chuck an Eaton locker in there. Just make sure your gear ratios are the same.

my 1999 has 325k miles on it who knows when the rearend gear oil was last changed going the get my machanic to change it soon. i wanta make mine into a camoer it is hard to mfind fermeldhide free matericals . everything has it paneling plywood press board insulation plywood. home depot does have fermeldhide free paneling 38.00 a sheet. in the 90s i built a chevy G10 to live in i used cheap 3.00 a sheet paneling from scottys it had fermeldhide in it and gave me resporitory problems it made my dog sick too. when i ripped all the paneling out i got better so did my dog

Sounds like some worn out bearings back in the rear axle. Like others have said, maybe run some heavier oil until you can get a rebuild. I personally think it’d be worth it to rebuild it. Those vans are cool!

i couldn’t tell exactly from the video. i would raise up the rear end get an automotive stethoscope, spin the wheels around and see if you can pinpoint the source. could it be the wheel bearings?

Digging the Astro stuff. Sub’d

Love the van content! Good luck with the rear end !

Definitely replace the rear end with another. Way cheaper and easier than rebuilding the rear end properly. The wear pattern on the ring gear didn't look good and if it is making noise, it is telling you it needs help. Take your time shopping around to find another as there are thousands and thousands out there. Go for low mileage and van condition when looking. Don't be afraid to be critical because it is you doing the work and living with it afterwards.

Doesn't look too too bad from what I could see. I would run it for the time being, maybe start researching/accumulating parts for a rebuild over the winter if possible, or find a junk yard unit to swap. Also, in my opinion, it is much more likely to have a driveshaft vibration than a vibration from the rear end. Something to keep in mind also, but that noise seems like rear end. Have you checked the wheel bearings in the rear?

You may have enough life on the rear end to shop the junk yards. You'll know it's time when the rear end whines all the time. 20 mph ...40 mph... 60 mph. Whining all the time , it's ready to go. Make sure the replacement has the same gear ratio. Number of teeth match.

ngl im here for scruffy content

Love the scruffy content!!!

When I picked up my Astro the diff was completely shot. Ended up having my shop swap one in from a Chevy pickup for about $900 Cad. If the rest of the van is in good condition Id say its worth the fix.

That's part of the bearing housing is what it looks like

Every adventure vehicle needs upgrades. Unless you buy a $100k van and it'll still probably still breakdown. If you keep it you definitely need to upgrade transmission and differential, especially if you plan to add weight. Those engines are pretty solid. Just look out for oil starvation on those Vortecs. Wish Toyota made bigger vans. 😂✌

I can smell this video

If you plan to keep the van and enjoy long road trips I would have the rear end professionally done.

Id pull a lower mileage one from an S10 with the same gearing. You can find some with a factory limited slip.

I would see if you could find an Astro/safari at a picknpull or scrapyard near you and look for a good rear end.

It better to buy a used rear end in Junkyard and put fresh oil if you know the rear is good. I'm think the cost is around $150 in your area. Differinal rear ends generally don't break down unless under extreme conditions. Like 4x4, rock crawling or towing with the van.

#LETSCRUFFYLIVE, even if you have to get it professionally done.

It’s easier to just go to the junk yard and pull a rear and out of the other vans but that sounds like a wheel bearing not rear end

My diff hums at 30mph. Seems to either quiet down or get drowned out by road noise at freeway speeds.

hey funny man. when the new videos will be! salon . how to store a large, and fit a sofa with a TV. to feel comfortable.astro in the USA is probably the same as UAZ 452 (loaf) in Russia. some carry a tool on it. and others go on trips where there are no roads. therefore, it is very interesting. just like a brother

Just buy a junkyard one, I bought one for my 02 Suburban from a guy in CDA. If you’d like I can get you his info. The nice thing is you can also upgrade to an LSD like I did. You could also just ignore it till it actually breaks like I did ;)

I assume with your mechanical skills you could take it off bring it to pro shop/machinist, have it rebuilt, put in the Diff back in etc and bang you've got another 75,000 miles or more in front of you.

you do it!

Hey dude, it looks like you have a crack in the pinion gear. Pause at 8:02 and look at about the 8 o'clock position.

I also started it t-shirt business for vanlifers and overlanders

Make sure you match from to rear end gear ratios, looks like your lash is toast, which means your ring and pinion should be replaced, And a bad bearing probably caused it, your diff needs a good going thru. You need a press for carrier bearings and pinion bearing installation as well dial indicators or depth micrometer for the ring and pinion set up. So price those out as well gears and a master rebuild kit to see your starting cost. Then balance that against a shop quote for the whole job, and if you plan on doing it think a week or two, I don’t mean to be a downer because I love your content. But don’t want to gaslight you either. Someone was in that diff before and did something wrong for it to go out like that.

Your pinion gear has a crack, at the 8 o’clock position.

That rubbing noise sounds like your finders rubbing your tire after your lift and new tires you put on???? Did you ever figure out what it was? I have a 2004 GMC Safari 2wd wish I had AwD but I just bought mine about 2 weeks ago 195k and I'm turning it into a camper van so far it's going good had to replace water pump and thermostat no more overheating but still have service engine soon light??? I think I have to do just a tune up new plugs and wires and hopefully that solves it just about to get it registered and hope it passes smog as long as my catalic converter isnt burned up lol 😆

That rear diff could use a rebuild it also looks like there is a crack on the pinnion the left hand side inbetween two of the teeth

I'm remembering now that you already did the s10 4x4 transfer case swap

Have you checked the universal joints?

Why no new vids? I hope all is good.

If you really have to rebuild it makes sure to put a locker in it while you have it apart

They make a additive for the rear diff…

Differential looks good. Pinion depth is too shallow and the bearings look like there’s too much runout. Wouldn’t be a tough rebuild. Also, I’ve watched you learn this much, you could rebuild it yourself. It’s not hard.

Seems like the gears are not meshing correctly, causing heat and noise. As to why, it could me mileage or someone did a poor job rebuilding it. I’d buy a locker for it if you rebuild it

Try off oven cleaner, the yellow can, for your unpainted pans. Mika

Fuuuck. My 1500 Silverado just making this noise with symptoms 😭

My astro worked great with a good tranny and diff so idk what you should do

I hope it's nothing too serious

It's time to call Scotty Kilmer hahaha

Engine mounts is the problems

ig you are going to change it and do it your self why not go with a limited slip differential or a locking differential