The British Historic Kart Club

I'm trying to remove and refit bearings on the 1-inch 3-bearing rear axle of my Zip Shadow class 4. The old ones don't seem to be willing to slide off easily. Does anyone know, should these just slide off after I've removed all the clips, keys, collars etc, or are they something like shrink fitted? Do I need to be more persuasive with them, should I use freeze spray on the axle? Or get someone who's properly equipped and knows what they're doing? Thanks. Peter

I use a hammer

Hi
After you have cleaned the axle up to get the bearings off, try sliding one of the new bearings on, but don't force it. If they do go on, you obviously have a problem with the old bearings that are still on the axle. You could try putting the bearings back to their original places. The bearings should have a collar. Obviously take all of the grub screws out and use a pair of mole grips or large pliers - something to grip the outer collar - and try and turn it on the axle. If it turns, try and turn it off slowly rather than going in a straight line. You could try pressing them off in a hydraulic press. Have you any pictures of what you have done to the axle up until now. Hope this helps - but don't blame me if it goes wrong!!

Good luck.

The collar Jim refers to is an eccentric fit to the bearing housing on older bearing types. The collar and bearing housing have to be turned in opposite directions to free bearing from shaft (and the grub screws must be removed as Jim referred to). If old and corroded they can be pain to release - coupled with the fact that they could be tightened in either direction so releasing them can be clock or anti clock.

Some collars have a 1/4" drilling in them and a dowel can be inserted and tapped to release eccentric lock. However, what normally happens is the dowel burrs the hole and wrecks it.... I have used a drift at an angle to knock the collar loose. Wrecks the collar but it will release the bearing.

New bearings and collars are available from Dartford karting or Simply Bearings. Simply bearings will even supply the old eccentric collar types if you phone them.

Bearings for 1" axle are either RA-100NPP8 (eccentric collar) or SBPFL205-16 (Parallel collar). If you fit either, when the collar is tightened remove the grub screw and drill the axle slightly for the grub screw to seat in. This will stop the axle moving sideways if you bump a kerb (or worse!)

Tim

That's been incredibly helpful, thanks everyone. I didn't know how it was all put together.

I used molegrips to hold the axle still and tapped the collars free using a drift. Two are now moving and one's soaking in WD40...

I have a new axle, and will change the bearings as well (thanks for the part number guidance, Tim. I knew Dartford had them, but Simply Bearings have an excellent website). I need to remove the old ones to save the brake carrier.

I did a bit of googling eccentric bearing collars, and found this helpful illustrated guide to installation, in case it's useful for anyone else as clueless as me. Knowing how it goes together helps to get it apart, particularly when choosing which direction to try tapping the collars.


Thanks again!

Peter

Somehow that link didn't appear when I hit "Submit". Changing parsing options and trying again:

http://www.ntn-kongo.co.jp/eng/handling/handling04.html

Hi Peter

If you bought your new axle from Dartford karting you may have to extend the 1/4" keyway to fit hubs, brake and sprocket. Its very irritating to start assembly only to discover no keyway where you need it!

Original axles had the keyway the full length.

Tim

PS. If you post a link hit the URL box above and insert the link between the [ ] brackets.

I finally freed that last pesky collar this weekend! It's taken one bent punch, loads of WD40, heat, and an attack with my Draper Dremel-copy multitool. Although I gave up my attempt to cut the collar off with the tiny milling bit, working from inside one of the grub screw holes, I suspect I must have somehow removed some kind of burr because a last desperate squirt of oil and a whack with a new punch suddenly shifted it.

Thanks for the heads-up Tim - the new axle is indeed from Dartford Karting, but after inspection the keyways seem to be of adequate length. It does have to go in the right way round, though, as one keyway is in the right place for the two bearings and sprocket on the left hand side and the other is ok for the single bearing and brake on the right hand side. I would have been cross if I hadn't spotted that in time.

Now I need to get an easy out into the pinch bolt holding the brake disc carrier to the axle. I managed to round off the internal hex.

Cheers for now. Peter