Author Topic: Front bearing replacement (Read 6192 times)

col320ce · « **on:** July 11, 2020, 13:54:25 »

These need doing and I've bever done this before. I've read up on it but I can't really work out if I really need some special tools. Is there an idiots guide to this somewhere and a recommendation on whether special tools are required?

col320ce · « **Reply #1 on:** July 15, 2020, 02:22:47 »

I'm in the midst of changing the front bearings and I have 2 potentially stupid questions:

1. I assume the outer bearing is tapped out the front of the hub and the inner bearing tapped out the back of the hub?

2. When I tap the new bearing in is there an obvious end point when they are seated correctly?

Thanks!

PeterPortugal · « **Reply #2 on:** July 15, 2020, 06:39:40 »

Hi Colin,

1. Yes

2. There is a shoulder they locate against. You should notice the sound as you tap, it goes "dull" when the outer race is fully located.

Regards

Peter

col320ce · « **Reply #3 on:** July 15, 2020, 11:21:06 »

I thought I’d do a quick write up on changing the front wheel bearings. It’s a 250SE/Cp but I’m sure it’s very similar to the W113. If there are any mistakes or additions please let me know...

Remove the wheel

Remove the brake caliper – Disconnect the break line (11mm) then bend back the tabs on the locking plate and remove the 2 19mm bolts. Just twist it a little to move the pads in a little to get over the lip on the disc. Pop a glove finger onto the brake line to stop contamination getting in.

Remove the cover/cap off the wheel hub. There is a puller for this but most use a screwdriver/wooden mallet arrangement.

Undo the hex bolt on the clamping nut and unscrew the clamping nut

Remove the washer

Remove the hub. This came off without any trouble

Clean the spindle and take the hub to the bench

Remove both outer races of the inner and outer roller cages – I used a brass block (something softer than the steel so you don’t damage the hub). Tapping it at 12 o’clock then 6 o’clock repeatedly gets them out.

Retain the puller ring (directly under the seal on the inside part of the hub).

Clean the 2 outer races as these are used to tap the new ones in.

Remove the disk from the hub if you’re changing this at the same time. These are on tight and I used “Loctitite seal and release” and a breaker bar to get them off. I held the hub in a bench vice ... you can also attach it to the wheel (off the car) and have someone stand on the tire. Put the new one on – 112Nm torque and use loctite on the threads.

Tap the outer race of both the inner and outer bearings. The ‘fat’ side goes in first. Best not to lube these as they go in in case it encourages them to move when driving. Use the old bearing race to tap it in. You’ll see that I used the bearing as well on the inside race as the hub got in the way before it was fully seated. The tone produced when hitting changes when they are fully seated.

Pack the bearings with the Mercedes high speed wheel grease. I measured out the recommended quantities (45-55g) which ended up being pretty much the exact amount you will use packing the bearings.

Put the inner on in first followed by the Puller Ring. Make sure the puller ring is the correct way around. Then tap the Seal in place.
Apply a little lube to the seal surface. The BBB says use Molykote paste.

Clean the disc with break cleaner

Pop it back on the spindle, put the outer bearing in, put a new washer on and screw the clamping nut back on until it stops. Back it off so that the washer can be only just moved by hand and tighten the clamping nut bolt.

Put the cap back on (with 20-25g of grease in it), make sure the copper grounding thing is present.

Put the caliper back on. Tighten to 112Nm and bend up the tabs on the locking plate. Re attach the brake fluid line.

Change the pads if required

Bleed the brakes

col320ce · « **Reply #4 on:** July 15, 2020, 11:22:38 »

more pix

col320ce · « **Reply #5 on:** July 15, 2020, 11:24:56 »

more pix

col320ce · « **Reply #6 on:** July 15, 2020, 11:26:10 »

more pix

col320ce · « **Reply #7 on:** July 15, 2020, 11:27:32 »

more pix

col320ce · « **Reply #8 on:** July 15, 2020, 11:28:44 »

Last of the pix

PeterPortugal · « **Reply #9 on:** July 15, 2020, 11:32:32 »

Colin,

Excellent. A very good contribution to the forum.

Two comments from me.
1. Retain the puller ring. YES, as these are 100 Euros plus tax each !! I am also not sure what they really do as so many people have commented here that they are missing on their cars.
2. In order to break the bolts holding the disc (rotor for the USA folks) to the hub you can bolt the hub to the spare wheel, lay the wheel on the ground and then have someone put their weight on the wheel. That worked for me.

Regards
Peter

yves · « **Reply #10 on:** July 15, 2020, 11:34:41 »

Good infos here ...

i'll use your pics if i need a bearing replacement Thank's for posting

PeterPortugal · « **Reply #11 on:** July 15, 2020, 11:48:41 »

Colin,

One more comment. I know that some people do not recommend lubricating the outer races to help get them in. You don't want these turning in operation. I took mine to a garage and they removed the old race and installed the new.

I never actually saw how they did it though !!

Regards

Peter

col320ce · « **Reply #12 on:** July 15, 2020, 12:08:06 »

Thanks for the info Peter on the greasing of the outer races... I'll edit the write up...

PeterPortugal · « **Reply #13 on:** July 15, 2020, 14:56:03 »

Colin,

The technical manual doesn't have much detail on wheel bearings. I suggest you take it up with your fellow Aussie Garry on how to input your article into this area.

Regards

Peter

col320ce · « **Reply #14 on:** July 18, 2020, 11:25:14 »

Great idea... I'll pm him soon.

PeterPortugal · « **Reply #15 on:** July 19, 2020, 08:47:18 »

Colin,

If you do manage to get the article together here is a picture showing how to deal with the bolts holding the discs to the hubs.

It really does make it easy.

Also it is recommended to use loctite on reassembly of these bolts.

Regards

Peter

col320ce · « **Reply #16 on:** July 20, 2020, 13:35:10 »

Hi Peter
I'll update it with the picture and loctite. I'll pull mine off and add loctite ... I debated it at the time.

hansr433 · « **Reply #17 on:** July 28, 2020, 17:05:33 »

Colin, great tutorial since I am forced to replace the bearings right now. See Exhibit A.

A little rant about Mercedes. I decided to order a kit from them since the EPC showed it coming with a hub, Exhibits B and C. Euro120 later I ended up with Exhibit D-H. Bearings made in Japan, the rest are cheap stampings, the dust cap does not fit and no hub. I could have ordered a kit with SKF or FAG German-made bearings for a third-less to half of what I paid Mercedes. Just plain highway robbery.

hansr433 · « **Reply #18 on:** July 28, 2020, 17:09:15 »

More photos

hansr433 · « **Reply #19 on:** July 28, 2020, 17:13:00 »

More photos. Sorry, forum system not being helpful.

hansr433 · « **Reply #20 on:** July 28, 2020, 17:14:07 »

Last 3 photos

hansr433 · « **Reply #21 on:** July 28, 2020, 17:14:24 »

2 photos to go

hansr433 · « **Reply #22 on:** July 28, 2020, 17:16:17 »

Last one

PeterPortugal · « **Reply #23 on:** July 28, 2020, 21:07:17 »

Hans,
Do not lose this part - it's the famous puller ring`. Costs more than 100 euros.
Peter

PeterPortugal · « **Reply #24 on:** July 28, 2020, 21:17:30 »

Hans,
I bought Febi Bilstein wheel bearing kit "05422". This all worked out fine apart from the hub cap. Also if we are being picky the cap head screw which is used to "lock" the big split nut which is fitted on the outside of the stub axle wasn't correct either. My old one was fine.

For the hub cap you need Meredes Part A 120 330 01 57. That is a copper coloured part which will fit your hub.

I still have the old SKF bearings in my garage and if you want the part numbers I will gladly give them to you.

Peter

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Author Topic: Front bearing replacement (Read 6192 times)