Heating Mk3 hubs to remove bearings
- Thread starter powerdoc
- Start date
- Status
- Joined
- Oct 19, 2005
- Messages
- 18,978
Hm, I don't know as when I have gotten '72 hubs too hot to handle and fumble with gloves the worn/rusty bearings stayed put until I injured myself mentally emotionally and physically using a Sharp chisel and sledge to get some bite on the tiny amount of bearing race not covered up by the spacer tube, which my'72's had 3 tube centering prongs at each end preventing knocking the spacer to one side to expose a reasonable amount of bearing ract to beat on. So by the time i farted around with about impossible task to me, the hubs had cooled down so just brute force resorted to - again, on quality fettering time with an old Commando. I ground out 3 notches on ends of spacer tubes so the next generation can knock em out w/o leaving more bad taste on Commando fettering that don't work as advertised. I now tend to flash on my and next generation - when aiming a power washer around hubs.
- Joined
- Jul 25, 2010
- Messages
- 5,912
If you wet your hand and shake it on it , and it goes sizzle hiss , its ready .
- Joined
- Jul 25, 2010
- Messages
- 5,912
you didnt say if it was preheated , did you put the Pie in too . Itll be pretty tough in 30 minutes .
10 to 20 , if that . did anyone mention GLOVES . big hairy leather welders or gardners gloves .
And dont drop it on the lino , or someone will be giveing it to you in the neck .
30 minutes & youll find its dropped out on its own accord .
Removed its going to charr anything it touches . so mind the curtains , breadboard etc .
a bucket of waters often usefull on these occasions . four warned is four armed . :twisted:
10 to 20 , if that . did anyone mention GLOVES . big hairy leather welders or gardners gloves .
And dont drop it on the lino , or someone will be giveing it to you in the neck .
30 minutes & youll find its dropped out on its own accord .
Removed its going to charr anything it touches . so mind the curtains , breadboard etc .
a bucket of waters often usefull on these occasions . four warned is four armed . :twisted:
powerdoc
VIP MEMBER
- Joined
- Apr 24, 2011
- Messages
- 354
VOILA! At 30min. in the oven, at 250 F, the hub was about 215 degrees. A few taps with the persuader and a brass drift and one side and the spacer were in the tub. I turned it over and a few more taps and the second dropped! It didn't take much force with the shop hammer to do it. Heat is a wonderful thing. Below is the setup I used to hold it.
[/URL]
- Joined
- Dec 28, 2009
- Messages
- 5,493
Presuming this is to fit the newer sealed-type bearings which are sitting on ice ,keep the oven hot as hub will need to be for next stage drop-ins. Final stage meat pie for dinner so as not to waste precious oven heat. :lol:
powerdoc
VIP MEMBER
- Joined
- Apr 24, 2011
- Messages
- 354
Actually, this is the first step in a nut-and-bolt refurbishment of my mk3. I will have to polish the hubs first then, as you correctly assumed, I'll be fitting sealed bearings. The rear hub is in the oven now; this will be a bit more challenging since I can't turn it over and beat it because of the shape of the hub. I'm hoping the friction of the vise effect of the 2x4's will help. I expect the rear hub may take more time because of greater bulk. The front hub cooled off relatively quickly to be able to be hand held after I removed the bearings and bits.
- Joined
- Dec 28, 2009
- Messages
- 5,493
Freeze new sealed bearings then drop or tap square into new hot hub. Save energy of oven to cook dinner after. How was meat pie for dinner ? now you have to get real with massive off-set of rear wheel MK111 . Lacing thread on the forum that will qualify you as an artiste. 
It's an art. Keep spinning and eyeballing. :wink:
It's an art. Keep spinning and eyeballing. :wink:powerdoc said:
Once the cush drive is removed there is no other bearing retainer on that side, the brake disc side has a seal but no retainer.
The tubular spacer located between the bearings has a stepped diameter which fits through and protrudes beyond brake side bearing.
Place an appropriate stepped drift into this protruding spacer, heating the cush side bearing housing and carefully tapping the drift will force the spacer against the cush drive side bearing and will displace it. The stepped drift is intended to protect and preserve the precision of the spacer collar by isolating direct hammer blows.
Once the cush side is withdrawn removing the brake side is straightforward.
Use of an oven only complicates the procedure, use an electric heat gun or sparingly a flame.
All the best.
I'm surprised that it's considered necessary to heat the hubs to this extent just to release their grip on the bearings. Not a practical proposition on an assembled wheel either. I find a kettle full of boiling water sufficient (especially good on the Mk3 rear as the conical hub can be filled-up).
Even on reasembly, hot water is Ok as it dries off immediately. A pint or two of boiling water exapnds the hub enough for the bearings to be a hand push-fit.
Even on reasembly, hot water is Ok as it dries off immediately. A pint or two of boiling water exapnds the hub enough for the bearings to be a hand push-fit.
powerdoc
VIP MEMBER
- Joined
- Apr 24, 2011
- Messages
- 354
Well, round two of heat and beat was a failure. The idea of filling up the hub with water would be interesting except it has holes in the hub that would let the water out unless it's just immersed in the water. I tried beating from both ends to no avail. Tried the blind bearing tool but couldn't get a good hold on it due to the spacer. Next heating attempt I'll try to find a socket which will hit the outer edge of the bearing to see if it'll budge. Gosh I love these old bikes.
- Joined
- Oct 19, 2005
- Messages
- 18,978
Hahaha to me now but ugh ugh ugh for you powerdoc. Now you are in hobot level of fettering hang up beyond the common sense advice that implies you just ain't up to owning a Commando. Re read my initial post for some insights. Once you do succeed make sure you 'over' heat the hub or can trap the new cold bearing cockeyed' then really have hurt sense of sanity to over heat to oil smoke burning hobot forced into level.
Current Old Brits supplied double row drum bearing requires some milling to deepen the drum bore as bearing slightly wider than stock.
Current Old Brits supplied double row drum bearing requires some milling to deepen the drum bore as bearing slightly wider than stock.
- Joined
- Dec 28, 2009
- Messages
- 5,493
I hope you have purchased the correct sealed bearings. Yes I heard there are oversize ones that require machining out the hub hole to drop in . Start measuring after you get that puppy out. :cry:
- Joined
- Nov 20, 2004
- Messages
- 20,720
Torontonian said:
The sometimes "oversize" sealed 4203 (17x40x17.5mm instead of 17x40x16mm) double-row ball bearing is the one that fits in the '71-on sprocket assembly (inc. 850 MkIII) it doesn't go in the hub as it would do for pre-'71 rear (non-cush) hubs.
The MkIII rear hub takes one 6203 (17x40x12mm) and one 6204 (20x47x14mm) bearing, the '71 - '74 rear hub uses two 6203 bearings.
- Status
