Need help with Bobcat 642 axle or bearing problem

[ibbuckshot]

Greeting folks, Some time ago I was throwing out questions about 642 drive chain size. I was wondering if I needed to replace the chains.....What was happening was then turning the machine, loading out of a stock pile or bank I would hear a hard bang noise which I thought was a drive chain jumping on a sprocket...After opening the machine up I removes the chains and took them to one of our local chain and bearing dealers...I was informed by then that the chains looked nearly new and that it would be a total waste of money to buy new ones...The sprockets look to be in very good condition....I purchases some half links thinking I could tighten the chains up.....I could not shorten them up at all....Soooo , it all went back together still not knowing what was causing the banging noise....Running the machine now with the , what seems like the metal to metal loud bang noise happening more frequently both while truning and digging we see the right front wheel skipping when the bang noise occurs... My question is , are there axle splines that engage with the drive sprockets? If so if this is the source of the banging when turning and digging what is the process for pulling this part of the machine apart? ? ? Also what kind of special " bobcat tools" are needed for the tear down ? Thirdly, does anyone have bearing and seal info and numbers for the 642......Thanks in advance for your help...
Have fun,
buckshot

 

[Jabonee]

Yes they are splined. You may have bad bearings. :confused3: Wheel hub is keyed. Check for sheared key.

 

[ibbuckshot]

Yes they are splined. You may have bad bearings. :confused3: Wheel hub is keyed. Check for sheared key.

jabonee,
Thanks for your help...I thought the axle / wheel hub were one piece...but there sure is something wrong inside... seems to be splines or key are meeting with a great deal of resistance in a turn which is normal ..... I can now see the front wheel skip a beat in the turn as the bang sound occurs ....and the rear wheel keeps turning as it should....Is there anyone out there with a 642 that can help describe the disassembly process and some of the part numbers?

Have fun,
buckshot

 

[Jabonee]

I would check the wheel hub first by removing the bolt and washer. There may be clear witness marks that indicate the axel is turning but the hub is not. Put a paint line across the hub and axel before you put the washer and bolt back on and take it for a drive. See if the paint marks still line up. I never seen splines get wiped but I have seen the hub keys sheer.

 

[ibbuckshot]

My 642 has no hub bolt....the wheel flange is part of the axle and I think must come apart from within

 

[Jabonee]

My 642 has no hub bolt....the wheel flange is part of the axle and I think must come apart from within

Parts breakdown shows bolt and washer. Can you post sn# :confused3:

 

[SSdoxie]

Early version 642 did have one piece forged axle and hub. Axle is held in place with a bolt thread into end of axle with washer pushing against the sprocket to apply correct bearing pre-load. No special tools required but trickiest part is reinstalling the seal without damaging it.

 

[ibbuckshot]

The serial number on this 642 is 5014-M-14213. I have it inside boom in the air, cab raised and ready to take it apart. Looking it over I am wondering if I can get away without tearing apart the steering...It looks like I can remove the "front" half of the chain case cover to get to the front axle and sprocket ? . If need be I may have to take apart all the steering linkages and connected parts. It sure would be nice to find someone who has done this before....Merry Christmas to all as well as a very happy, healthy and prosperous New Year...
Have fun
buckshot

 

[Jabonee]

Your should not have to remove the steering if you can get the front case cover off. You will need a small block of steel that just fits between the L and R sprocket bolts. Loosen the suspect axle sprocket bolt against the block jacking the axle out.

 

[ibbuckshot]

Well, I got the sprocket off and the axle out.....the splines and bearings are in great shape...Nothing slipping there...I'll put a new axle seal in and get it back together.....I am now still searching for what is causing this bang noise.....Does anyone know what the measurement for the amount of slack in the chains should be? I am at a loss on what is causing this banging noise when loading or in forward motion...