Seriously? You want me to What?

[Grabinov911]

Yup. That was me at Spring Fling in SoCal negotiating with Dr. Diff for the new 489 case Eaton True-Trac 3.55 rear end for my '70 Roadrunner. I couldn't help myself, since that was one of the items on my list for the car, which had a 3.23 open rear end - which ain't great for handling or performance.



So I set about getting it installed this week. Axles came out with no problems at all - after a few minutes of "not getting it". The service manual says to use the hole in the axle flange to access the axle bearing hold-down bolts. IT'S THE BIGGER OF THE HOLES IN THE FLANGE! YOU SEE, THEY'RE NOT ALL THE SAME SIZE! While I was in there I decided to change out the bearings. the car has 50,000 miles and is 40 years old after all. Dr. Diff sold me the proper Green Bearings for the replacement. With all the debate about Green vs. Timken, I figured if they came from him, they were good enough for me. Read on in the service manual as it described the technique for beating the axle bearing holder and axle race into submission. Seriously? You want me to what? Beat on the holder with a chisel without nicking the axle? Split the carrier with a chisel? Grind off the bearing race to remove the rollers? I did one axle this way - most of it at least before I scared myself - worried about destroying the axle.

This is what's left when you do it the factory way:




Well That's about enough of that. This is why there are places called So and So's Axle and Driveline. Took them about half a day and voila, you get this:



Removed the old diff by loosening all of the hold down bolts and pushing up on the front of the case with a floor jack - just enough to split the case and drain the fluid into a drain pan. So proud of myself at this point - and wondering what was about to go wrong. Nothing's ever easy with this car. I removed all of the nuts and allowed the old diff to rest on the jack - still balanced by the studs in the axle. It felt so light - I told myself this must be because it's an open diff. The new one from Dr. Diff is so much heavier. Huh. whatever. Had my son (9 years old) pull the jack out. No problem, now I'll just slide it off the studs and onto the floor - 12 inches down. WHAM!

Well not exactly WHAM. That is the sound the diff would have made if it had landed on the cardboard on the floor. It didn't make that sound because the blow was softened by my (gloved) wrist. It actually sent a shock up my arm. I pulled my arm out expecting to see my wrist severed, but luckily it was just a bruise. Hurt like hell for a day or two though. Don't do that. Get someone to lower the diff ON the jack. Or just let it fall on the floor - it's coming out anyway. I had actually thought about all of this in advance and then failed to listen to my own advice. Does this ever happen to you?

So I waited two days for the swelling and bruising to subside and had my son help me lift the new diff into place with the jack. No problems. It is nice working on gears that are actually an inch or more across. A slight bump against the housing is not going to hurt that thing! And the studs allow it to slide on perfectly. This is my kind of install. fits in one direction only with no adjustment. I used a FelPro gasket with liberal amounts of Permatex to make sure it won't leak. Why? 1.) I HATE things that leak, and 2.) I am NEVER going to do this again by myself on my back, so if the diff is a bit stuck, someone with a lift will be dealing with it!



Beautiful.

The axles went right back in. No adjustment with the Green bearings, so just tighten 'em em up - with a little bit of Permatex on the gasket for good measure. the last thing I did was add new gear oil to my new diff. Cass (Dr. Diff) recommended 85/140 conventional, so I bought enough for the 4.4 quarts shown in the service manual. I started with the rear of the car up in the air, but only got about 2 quarts in before the oil was coming back out the fill hole. I can't lower the rear or I'd never get the oil in (with the car sitting on the ground), so I raised the front. This did two things for me. First, it allowed me to get another quart of oil into the diff before it started to drip out the filler. Second, it allowed me to drain about a quart of trans fluid out of the automatic trans housing - oh yeah, did I forget to mention that I had taken out the driveshaft to change the U-joints? LUCKILY I had placed a pan under the trans when I removed the driveshaft in the first place.

One strange outcome though: I was only able to get 3 quarts of gear oil into the diff even with the car level. The service manual says it should take 4.4 quarts. Anyone know why this would be? Is there a quart+ of oil that was still inside the axle housing even though I had the differential off? I didn't go to any effort to drain or dry it other than removing the differential. Anyone have an idea? How do I know FOR SURE that there is enough oil in there? I guess I need a lift...

 

[68sportsatelliteragtop]

Check your service manual again
Mine says 4 PINTS (3 1/4 Imperial)

 

[Bee383]

My 69 bee is in my tranny guys shop having a truetrac unit and 3.73 gears.i was a little bit leery of taking on this one.good job doing it yourself!

 

[red 69 runner]

how much did you pay for the diff and the bearings?

 

[HT413]

Lol, thanks for the story, every time I work on the car it's an 'adventure'.

 

[Garys1969RR]

The 2 times I have changed to a 3.91 posi unit, we just put a milk crate or pallet under there for it to land on. Didn't care much for the old 2.76 open unit anyway. Or 1 guy on each side can ease it down. Same with the install. 2 strong guys can usually get it in. I have lifted it in alone, but takes quite an effort. Far as the bearings go, have never had 1 go bad. But the axle shop looks like the way to go for bearing installation to the axle.

 

[Bee383]

I watched a twenty something kid pull mine out at the shop and carry it over to a workbench like it was nothing.i have an extra one in my garage that I can barely drag around

 

[Grabinov911]

Ooohhh... Do I have to say? $1,300 with the whole enchilada and the bearings too. It felt expensive compared to some of the stuff for sale at the show, but then: It's from Dr. Diff so I figured it was at least a FAIR price and it was very high quality; It's from Dr. Diff so I don't have to worry about if it's set up right, which ain't easy and I'd never know the difference on one from someone I didn't know; It included the new heavy duty pinion yoke which - having looked now, is worth $100 or more; It is built in a new nodular iron Yukon case with brand new Yukon gears; and I didn't have to pay to ship it - Cass even helped me carry it halfway across the show to take it home.

I'm sure someone will tell me if I overpaid, but I'm comfortable with it. I KNOW it's good to go...

- - - Updated - - -

Check your service manual again
Mine says 4 PINTS (3 1/4 Imperial)

Oh. Well. Uhhh... I better check again. I guess there's little chance of overfilling it, since it runs right back out!

Yeah. It's pints. 4.4 of them.

 

[Bee383]

I paid 550'for truetrac unit and 400 for Yukon gears and about 100 for install kit.not sure what labor will be.i was just afraid i woulnt get r&p set up right.

 

[cdr]

thanx for sharing your 8 3/4 adventure!!!! you tell a great story, very funny ----but not, glad you didn't get hurt bad! funny cause i can relate to my car trying to injure me..

 

[Grabinov911]

Milk crate. Now that's a good idea. But I would have had to move 5 or 10 feet to get one - like all the way to the edge of the garage. Probably should have done that.

You guys are great. This site is awesome.

 

[Kern Dog]

I like Dr Diff and have done business with him. He is one of the few out there that take the time to get things right.
I currently run the NON adjustable axle bearings but am looking to go back to the timken roller bearings. I have about 8000 miles on these axles and am on my second set of bearings. These type just do not last. The physics tell the tale. The "Green" brand as well as ones from other vendors use a series of ball bearings with a fraction of the contact area of the tapered Timkens. No wonder they wear out like a paper towel hat in a rainstorm.
My Charger is set up for handling.I'm taking bigger t bars, sway bars, Frame connectors, torque boxes, welded and reinforced K member...The good stuff. When I got my axles, I took the advice from a salesman at Moser engineering and went with these non adjustable types. The cornering loads that these bearings see absolutely guarantee an early failure. The Timkens were 100,000 mile durable. I went through the first set of the Greens in 5800 miles. I have never autocrossed the car. I don't spend every mile on freeway on-ramps either. In short, their only advantage is that you install them and skip adjustment. The adjutment takes a few minutes. I screwed the pooch though. My axle shafts have been modified, the housing has been narrowed and I can't just have Timkens pressed on mine. I'll need new axle shafts at this point.
I hope that your experience is better than mine. I didn't mean to crap on your thread here, I just wanted to warn you of what is coming. Keep an ear open to whine, rumbling and leakage if you like to corner much.

 

[rebootej]

Ive experienced this fun, too many times. I actually made a wooden piece with wires that wires the 3rd member to the jack.

 

[Grabinov911]

Hey Greg C (I'm Greg R actually),

When you go from Green type back to Timken type bearings, how do you get the "crush sleeve" into the center of the differential? From the looks of my stock diff, and from reading about it, there's a part in the diff that goes between the axle ends when you are running adjustable bearings. It seems to be called the crush sleeve. Tell me I don't have to pull the diff to put one in if I switch back???

 

[Kern Dog]

I believe the crush sleeve is a part that is used with the install of the pinion shaft. Maybe what you are thinking of is the "Thrust Button"? I still have the thrust buttons in all of the 8 3/4" gearsets that I have here. I am currently using a '489 case with 3.91 gears and a clutch type LSD.

 

[tallhair]

Removed the old diff by loosening all of the hold down bolts and pushing up on the front of the case with a floor jack - just enough to split the case and drain the fluid into a drain pan. So proud of myself at this point - and wondering what was about to go wrong. Nothing's ever easy with this car. I removed all of the nuts and allowed the old diff to rest on the jack - still balanced by the studs in the axle. It felt so light - I told myself this must be because it's an open diff. The new one from Dr. Diff is so much heavier. Huh. whatever. Had my son (9 years old) pull the jack out. No problem, now I'll just slide it off the studs and onto the floor - 12 inches down. WHAM!

Well not exactly WHAM. That is the sound the diff would have made if it had landed on the cardboard on the floor. It didn't make that sound because the blow was softened by my (gloved) wrist. It actually sent a shock up my arm. I pulled my arm out expecting to see my wrist severed, but luckily it was just a bruise. Hurt like hell for a day or two though. Don't do that. Get someone to lower the diff ON the jack. Or just let it fall on the floor - it's coming out anyway. I had actually thought about all of this in advance and then failed to listen to my own advice. Does this ever happen to you?

.....

The axles went right back in. No adjustment with the Green bearings, so just tighten 'em em up - with a little bit of Permatex on the gasket for good measure. the last thing I did was add new gear oil to my new diff. Cass (Dr. Diff) recommended 85/140 conventional, so I bought enough for the 4.4 quarts shown in the service manual. I started with the rear of the car up in the air, but only got about 2 quarts in before the oil was coming back out the fill hole. I can't lower the rear or I'd never get the oil in (with the car sitting on the ground), so I raised the front. This did two things for me. First, it allowed me to get another quart of oil into the diff before it started to drip out the filler. Second, it allowed me to drain about a quart of trans fluid out of the automatic trans housing - oh yeah, did I forget to mention that I had taken out the driveshaft to change the U-joints? LUCKILY I had placed a pan under the trans when I removed the driveshaft in the first place.

.....

Anyone have an idea? How do I know FOR SURE that there is enough oil in there? I guess I need a lift...

Loved this post Grabinov911. Maybe your userid should be Grabbin911 LOL. Thanks for the post and the story tellin'. You have a gift and I'm glad your wrist is apparently OK.

Well that last qustions was answered but you could use 4 jackstands to get the car level and up in the air enough then remove the rear end drain plug, the extra diff grease will drain to proper fill level. I don't know if overfilling it will have any negative impact ?? but I'd check before I ran it over filled. Someone will pipe up on this point I imagine to let you know if it's OK or not.

 

[Cranky]

An 8 3/4 3rd member, chunk, pig, drop out (take your pick ) is 'only' about 80 lbs...are y'all a bunch of pansies?? JK JK. Yeah it's heavy. I used to pull em out on my gut and just roll over and lay it down. Same thing going back in but started using a floor jack several years ago. Much easier!

On the Greens, I'm thinking that True Trac doesn't have a thrust pin in the center so you're stuck using that bearing. When it first came out, it was a drag racing deal since a ball bearing takes less (robs less) power to turn but like Greg C mentioned, the Timkens are way more durable and will hold up to high cornering loads. Other manufactures also used ball bearings on their axles and yes, they were usually a higher maintenance item.

As for a crush sleeve...it's a pinion shaft part that only the 89 case uses....the axle thrust pin is what you need inside the 3rd member that's needed when tapered roller bearings are used and all the 3rd members need one when Timkens are used.

 

[Grabinov911]

On the Greens, I'm thinking that True Trac doesn't have a thrust pin in the center so you're stuck using that bearing. When it first came out, it was a drag racing deal since a ball bearing takes less (robs less) power to turn but like Greg C mentioned, the Timkens are way more durable and will hold up to high cornering loads. Other manufactures also used ball bearings on their axles and yes, they were usually a higher maintenance item.

As for a crush sleeve...it's a pinion shaft part that only the 89 case uses....the axle thrust pin is what you need inside the 3rd member that's needed when tapered roller bearings are used and all the 3rd members need one when Timkens are used.

I believe the crush sleeve is a part that is used with the install of the pinion shaft. Maybe what you are thinking of is the "Thrust Button"? I still have the thrust buttons in all of the 8 3/4" gearsets that I have here. I am currently using a '489 case with 3.91 gears and a clutch type LSD.

There ya go. The thrust pin is what I was thinking of. I guess I'll listen for the howl and then see what it takes to switch back to Timkens - if it's possible with the True Trac. As you guys know, it's a "road racing" type of setup that I'm aiming for, so the Green's may not last long. On the other hand, with the car on jackstands in the garage, they'll probably last years!

Loved this post Grabinov911. Maybe your userid should be Grabbin911 LOL. Thanks for the post and the story tellin'. You have a gift and I'm glad your wrist is apparently OK.

Thanks Tall. Yeah the user name is just a combination of my first and (shortened) last names, and "911" as in "dial 911". It's boring and was just something I was using on other logins, like email, etc. I use ChainDrive (cause I'm really a moto guy) on some other sites and if I could figure out a way to transition to that one here, I'd do it. either way, thanks for the compliment. I try to add interest and leave it to the real motorheads to add, you know, facts...

 

[Supershafts]

I like Dr Diff and have done business with him. He is one of the few out there that take the time to get things right.
I currently run the NON adjustable axle bearings but am looking to go back to the timken roller bearings. I have about 8000 miles on these axles and am on my second set of bearings. These type just do not last. The physics tell the tale. The "Green" brand as well as ones from other vendors use a series of ball bearings with a fraction of the contact area of the tapered Timkens. No wonder they wear out like a paper towel hat in a rainstorm.
My Charger is set up for handling.I'm taking bigger t bars, sway bars, Frame connectors, torque boxes, welded and reinforced K member...The good stuff. When I got my axles, I took the advice from a salesman at Moser engineering and went with these non adjustable types. The cornering loads that these bearings see absolutely guarantee an early failure. The Timkens were 100,000 mile durable. I went through the first set of the Greens in 5800 miles. I have never autocrossed the car. I don't spend every mile on freeway on-ramps either. In short, their only advantage is that you install them and skip adjustment. The adjutment takes a few minutes. I screwed the pooch though. My axle shafts have been modified, the housing has been narrowed and I can't just have Timkens pressed on mine. I'll need new axle shafts at this point.
I hope that your experience is better than mine. I didn't mean to crap on your thread here, I just wanted to warn you of what is coming. Keep an ear open to whine, rumbling and leakage if you like to corner much.

Why didn't you change the ends when you narrowed it so you can use the other bearing and have no adjustment, didn't the shop bring that up when they narrowed it ?

.

 

[440+6]

Good job and a fun read. I know where your coming from I have quite a few stories that end in "never again" but the satisfaction of doing it yourself makes it worth the effort.