8 3/4" sure-grip swap and rebuild questions
- Thread starter MopaR&D
- Start date
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MopaR&D
Nerd Member
Son of a... well at least now I know LOL. I saw that kit listed on Summit with no specs to speak of but didn't think to check the manufacturer's website.
I have new Mitutoyo electronic calipers coming in the mail today (got tired of using inaccurate and unreliable Harbor Freight junk) and the shims should be arriving tomorrow, both from McMaster. Damn I love that site.
I also stopped by Lowe's Tuesday after work and picked up a Craftsman 1/2"-drive 50-250 lb-ft clicker torque wrench upon the recommendation of a car buddy who restores cars (and freight trains lol) for a living. Thing is pretty nice for being 100 bucks, almost 3 feet long for extra leverage with a decent carrying case and even came with a calibration certificate. Now I can properly torque the pinion nut without using my impact.
Supposed to be somewhat cold this weekend but I think tidying up my garage and getting my propane heater fired up will help with morale lol. I'm mentally preparing myself to make this 3rd-member my b*tch and do whatever it takes to make it right.
mderoy340
Well-Known Member
Stick with it and take your time. I've walked away more than once and started the next day with a fresh mind. The more setups you do the better you get at it. Also 400 grit on a piece of glass can work to remove .001
MopaR&D
Nerd Member
Ok, here's the pattern now with an extra .004" behind the inner pinion bearing... about to run to the parts store for a new inner bearing, gasket and limited slip additive
MopaR&D
Nerd Member
@john-9 @mderoy340 or anyone else? I know the pattern doesn't look great I forgot to clean the gear oil off the teeth so it kind of smeared the paint but you can clearly see the contact has moved toward the toe of the gear teeth. I was ready to press on the new inner bearing yesterday but stopped myself, I want your guys' feedback first so I don't go through this mess again.
mopowers
Well-Known Member
What's the backlash with the new pattern? Are you applying drag when you run a pattern? Are you running a pattern in multiple locations on the ring gear? If so, do they all look the same?
Just curious - when you took it out after the first time, did you double check the backlash before disassembling? Did it change?
Just curious - when you took it out after the first time, did you double check the backlash before disassembling? Did it change?
MopaR&D
Nerd Member
I didn't check the backlash when I removed it and didn't set the backlash with a dial indicator before checking the pattern this time (just went by feel), I found that last time varying the backlash from .006" to .010" barely had an effect on the pattern. Last time I checked the pattern (before the first install) it wiped the paint in 3 places and the pattern looked exactly the same in all spots.
I guess tonight I'll put it back together with the gear teeth cleaned of residual gear oil, set the backlash properly with my dial indicator and check the pattern for the 10987298th time lmao.
And yes I'm applying drag with that screwdriver you see sticking out the top. I push the screwdriver down and in to put drag on the carrier while turning the pinion yoke by hand.
mderoy340
Well-Known Member
I check gear pattern in 4 places after setting backlash to gear manufacture instructions. Every time you change the shim the procedure needs to be the same.
MopaR&D
Nerd Member
Ok I think I got it. Put it back together and set the backlash at .007", got the same pattern. I then took .001" out of the pinion (from .040" to .039" total shim thickness) and the pattern moved just a hair towards the center. It's still smudging a bit as I couldn't get the old gear oil completely removed but I think I can finally put it all back together?
First pic is .040" pinion depth shims, second is .039"
First pic is .040" pinion depth shims, second is .039"
MopaR&D
Nerd Member
I skipped going to the gym yesterday after work to hopefully get the 3rd member done and back into the car but I ran into an issue that I should have known to avoid but I was being impatient and stupid. Probably obvious to the more experienced but DO NOT USE AN IMPACT to torque the pinion nut! After so many times installing then removing then reinstalling the pinion and using my impact to torque the pinion nut I ended up ruining the outer pinion bearing cone. Got it together then when I went to check the turning torque it didn't turn smoothly, felt like it was rolling on marbles or something. Also noticed I kept having to take out preload shims to maintain correct preload. I removed the seal and outer bearing cone and turning the rollers in my hand you could feel it was "bumpy". My guess is the rollers hammered themselves into the inner race. D'oh!
I had to spend extra time running to the store to get a new bearing and seal and then again going through the process of figuring out pinion preload spacers, this time using my new "big" torque wrench to properly torque the pinion nut each time. The inner cone is new too I didn't use the impact after pressing that one on the pinion.
Really hoping to have this done tomorrow or Saturday at the latest, I'd like to go to the rifle range Sunday with my brother and after that I'll be in a world of darkness since DST is ending.
Quick question, would lightly wetting the paper 3rd member gasket with gear oil keep it from sticking to the mating surfaces for easier removal, or would that make it more prone to leak? I don't want to use RTV or anything sticky so it's easier to swap out pumpkins. I tried some gasket stuff last time (forget the name exactly) but it ended up acting like an adhesive and I had to scrape it off with a razor blade.
I had to spend extra time running to the store to get a new bearing and seal and then again going through the process of figuring out pinion preload spacers, this time using my new "big" torque wrench to properly torque the pinion nut each time. The inner cone is new too I didn't use the impact after pressing that one on the pinion.
Really hoping to have this done tomorrow or Saturday at the latest, I'd like to go to the rifle range Sunday with my brother and after that I'll be in a world of darkness since DST is ending.
Quick question, would lightly wetting the paper 3rd member gasket with gear oil keep it from sticking to the mating surfaces for easier removal, or would that make it more prone to leak? I don't want to use RTV or anything sticky so it's easier to swap out pumpkins. I tried some gasket stuff last time (forget the name exactly) but it ended up acting like an adhesive and I had to scrape it off with a razor blade.
mderoy340
Well-Known Member
Do you use it on both sides of the gasket?
mderoy340
Well-Known Member
Yes. I also retorque several times after running a while. Leaks normally start around the stud area on my stuff.Do you use it on both sides of the gasket?
MopaR&D
Nerd Member
Well I'm sad to report it still whines. At lower speeds (under about 40) it whines on coast, at higher speeds it whines lightly on acceleration. I drove it about 10 miles and the sound stayed the same. I put it back together with .007" backlash and the pattern still looked like the last pic I posted. What gives? What will happen if I just keep driving it and ignore the noise? I did touch the rear end housing in the center after driving and it was pretty warm.
If the pinion depth needs to be readjusted I'm going to take the 3rd member to a shop, this project killed me. I might be able to readjust backlash but that's as much as I'm willing to do at this point.
If the pinion depth needs to be readjusted I'm going to take the 3rd member to a shop, this project killed me. I might be able to readjust backlash but that's as much as I'm willing to do at this point.
mopowers
Well-Known Member
What brand gears are they? Some of the cheaper brands just have a tendancy to make noise.
MopaR&D
Nerd Member
I checked my invoice from Dr Diff and they're Motive brand. Honestly if it doesn't mean the gears will shred themselves I'll just deal with the noise. I imagine taking it to a shop will cost a decent amount and the pattern looked good so idk what's up.
MopaR&D
Nerd Member
I recorded a video of the noise while driving at various speeds. It's a bit long but I wanted to capture the sounds as best as possible.
MopaR&D
Nerd Member
So everywhere I've read says that noisy gears will either stay noisy or get worse over time. I'm not sure how but after doing a few more short drives to break in the gears the noise has gotten noticeably quieter, particularly after I did a holeshot and WOT pull up to about 70 mph. It's still there for sure but it's not nearly as bad as the first time I drove the car after adjusting pinion depth and backlash and reinstalling the pumpkin this last time. I realized after searching and reading some older threads I didn't set the backlash in the best way so that might have been the issue, maybe I'll pull it and reset but it's gonna be a while until I'm feeling up to taking the pumpkin out again. Unless I can take it over to my buddy's giant garage with a lift and good lighting and heat lol.
dude.....you are killin it!! If beating on it made it better......you know there is only ONE thing to do.....
It has too much pinion gear depth. You need to back it out a little.
Also, FWIW, I don't use a gasket on 3rd member style rear axles. RTV only. It's always worked well for me.
MopaR&D
Nerd Member
I wouldn't be surprised but I just straight up don't have the energy to pull this thing and take it apart for a third time. I thought about putting a .038" shim pack behind the pinion (has .039" now, started with .035" and that was too far "out") but I was sooo over it I just ran out of patience. Already threw about $80 in the trash doing it a second time. I know it's the right thing to do but I just can't bring myself to do it. If it was still reasonably warm outside and didn't get dark by 5:00PM I might be more motivated. Also just a lot of stress from other life stuff like applying for jobs and keeping up with going to the gym, cleaning my house, feeding myself, taking care of my cat, putting up with a job I don't like etc etc. I need my Duster running because it's the only way I can really release after a rough day. And boy these gears made it quite a rush, with all the BS I'm still glad I did it. Being able to get rubber all the way through 1st gear is just fantastic.
I've successfully used RTV as well but I HATE having to spend 30+ minutes scraping off every last little bit of rubbery goo so it seals on the next install. The paper gasket seems to be holding up well I don't see any seepage from the case/housing. I just want to be able to swap center sections quickly. Which reminds me I still need to bolt my 2.94 ring gear on the open diff I took out of the 489 case and put it back in my old 741 case... who knows when that'll happen.
30 minutes? What have you been using to scrape it off with, a dull butter knife? It cleans right up with a razor blade scraper.
MopaR&D
Nerd Member
30 minutes was an exaggeration it's probably more like 20? lol... The mating surface on the pumpkin is pretty easy but on the housing with all the studs sticking out it's a pain. The scraper tool is too bulky for getting around the studs in my experience, I have to use a razor blade by itself while laying under the car and using a magnetic flashlight to see. My housing also has a bunch of little nicks and burrs around the edges of the mating surface that catch on the blade grrr
MopaR&D
Nerd Member
Figured I'd bring back this thread just to give an update. After moving and getting settled in (as well as other maintenance and upgrade projects on my Duster) I finally got around to pulling the 3rd member back out as I needed to change the gear oil after the first 500 break-in miles. I checked the backlash and it was at .009"; I opened it up to .010" and filled it back up with fresh conventional 80W-90 oil and limited-slip additive. Noise has not changed, it still has a mild-to-moderate whine that is worst around 65-70 MPH (gets quieter above and below those speeds). For now I'm just going to deal with the noise as I don't cruise on the highway as much with these gears. Later on when I finally swap in a TKX trans and start to do more highway cruising with the overdrive I might dive back in and adjust the pinion depth but I'm inclined to just get a higher-quality ring and pinion and try again. I've been finding more than a few reviews all over the web posted within a few years of when I bought mine (2017) of people saying they could not get their Motive gears quiet no matter what they did, usually mentioning that they have experience putting together rear ends and have successfully swapped new ring & pinion sets in the past that didn't make noise. Maybe I just got unlucky with a bad batch but I'm not inclined to take a chance with that brand again.
Why would you open it up instead of closing it up to 7 or 8? It's going to wear past 10 after you drive it a while.
Aren't tighter clearances quieter?
Aren't tighter clearances quieter?
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