Front axel

[sjtymko]

After reviewing the how-to on CGW concerning the front axel/hubs/etc, I have a couple of questions:

1. What of all the special tools are really necessary, I already have the hub nut tool? If many others are not necessary, what to use in their place?

2. The parts list lists some generic part numbers. What manufacturer's numbers are these and where is the best place to get them?

Thanks, Steve

[Hipine]

The generic part numbers are not manufacturer specific. The bearing numbers are industry standards. The seal numbers are Chicago Rawhide numbers which are xrfable to any brand, your supplier will know by the CR prefix. But I don't recommend the CR seals. The tripple-lim MB seals are much better quality and worth the price difference. Not so with the bearings though, as the ones now coming in MB boxes are sourced from all over the world, different brands and countries. You're better off going with a manufacturer/location you trust.

Re: Tools

I didn't use any of the MB tools except the hub nut. Outer races for all bearings can be drifted out. The only bearing I needed a puller for was the inner race of the outer hub bearing. It's pressed against the hub face and required use of a knife-edge type bearing splitter to remove. I can send you a picture if you want. I have all the pix for an article, but no time to write it yet. But if you bring the manual page that shows the bearing on the hub to your bearing supply and tell them you need a knife-edge splitter to do "this" removal job, they should be able to steer you in the right direction.

-Dave G.

[sjtymko]

The generic part numbers are not manufacturer specific. The bearing numbers are industry standards. The seal numbers are Chicago Rawhide numbers which are xrfable to any brand, your supplier will know by the CR prefix. But I don't recommend the CR seals. The tripple-lim MB seals are much better quality and worth the price difference. Not so with the bearings though, as the ones now coming in MB boxes are sourced from all over the world, different brands and countries. You're better off going with a manufacturer/location you trust.

Re: Tools

I didn't use any of the MB tools except the hub nut. Outer races for all bearings can be drifted out. The only bearing I needed a puller for was the inner race of the outer hub bearing. It's pressed against the hub face and required use of a knife-edge type bearing splitter to remove. I can send you a picture if you want. I have all the pix for an article, but no time to write it yet. But if you bring the manual page that shows the bearing on the hub to your bearing supply and tell them you need a knife-edge splitter to do "this" removal job, they should be able to steer you in the right direction.

-Dave G.

Thanks again Dave, you are always such a great help! No pics necessary, I am sure I will be just fine. My only other question is how to get around that slide hammer looking tool used to remove the wheel cap and does the "retaining wrench" pictured in the manual really do much that a pry bar or large screw driver couldn't do with the wheel bolts in place?

Lastly, how tight do you preload the hub nuts?

Thanks again,
Steve

[Hipine]

....how to get around that slide hammer looking tool used to remove the wheel cap.....

A screw driver works just fine if you pry a bit at a time working your way around the perimeter of the cap. The cap is no different than ten billion others on other vehicles. Typical MB stuff with the special tool to pull a grease cap. [:)]

...and does the "retaining wrench" pictured in the manual really do much that a pry bar or large screw driver couldn't do with the wheel bolts in place?...

I actually prefer to do this final hub tightening with the wheel in place. It gives you a nice lever arm, and just wedging your boot toe between tire and ground with tire slightly elevated gets you all the friction you need to put lots of force on the bearings for preload.

...Lastly, how tight do you preload the hub nuts?...

I did mine with NEW nuts and NEW CV stub threads, so best possible situation with regard to thread clearances, but I did the following:

Inner to 200 Nm while spinning wheel (to me this is excessive, all play is removed by 100 or 150 Nm)
Back off inner nut without moving wheel
Hand tighten inner nut, or maybe 5 Nm
Back off inner nut 1/8 turn
Place lock washer
Tighten outer nut to 200 Nm
Bend lock washer tab

I'd say always use new lock nuts and washers, and clean the threads on the CV stub really well before giving them a light coating of grease. If the threads on your CVs are worn, then compensate by backing off more than 1/8 turn on that inner nut, maybe closer to 1/6 turn.

You want these bearings to be pre-loaded. Tapered roller bearings don't wear out from being too tight, they wear out from being too loose. The silly MB manual asks you to verify something silly like 0.02mm of play in the bearings. 0.02mm is less than one one-thousandth of an inch. Crazy talk. Most people will take the idea of verifying some play to mean that play is perceptible by feel, and will start out with the bearings too loose.

As long as the wheel spins freely after you're done, and you can't feel any play in the system, you're fine. If you're ultra paranoid, like I am, then pull over after 20 miles of highway driving (use brakes as little as possible in stopping) and touch the metal tabs of the hub where they protrude through the steel rim center to judge hub temp. Do it again after driving 50 miles or so straight. They should always feel cool to the touch unless you've heated them with braking.

As long as the hubs stay cool, the bearing preload is not excessive.

-Dave G.

[sjtymko]