SRAM MTH-506 R hub, query RE bearings & hubs

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RecumbentRide
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SRAM MTH-506 R hub, query RE bearings & hubs

Post by RecumbentRide »

I've got a SRAM MTH-506 R(ear) hub which started to grind on my last ride. When I got back I noticed play on one side of the hub i.e. the drive side. Taking hubs apart is not one of my favourite tasks as I'm visualizing bearings escaping left, right and centre. Anyway this didn't happen but upon disassembly I noticed the drive side bearing grease was pretty cruddy whereas the other side was clean as a whistle. The drive side cone is done for and the cup doesn't look great but I'm pretty sure I can clean it up (though I'll probably replace the whole core). Now I can get a core (the bit that the cassette mounts onto and includes the bearing cup) but where my knowledge runs out is where do I get replacement ball bearings (and possibly cup if the very clean non-drive side is also a bit worn), ball bearings tbh are the priority right now. I've looked up SRAM service docs online and nothing tells me what I should be looking for. I'm also aware I'm going to have to get the Freehub Body Removal tool (11mm).

I'll soon be replacing these wheels and wanted to ask would I be better off getting hubs with cartridge bearings rather than the traditional cone & bearing setup. I imagine cartridge offers a lot of advantages.

Last question, I have a 1x12 speed setup so with my new wheels I'll be sticking with this. Which of the following gives me the best options Shimano freehub, XD drive or Microspline?
zenitb
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Re: SRAM MTH-506 R hub, query RE bearings & hubs

Post by zenitb »

If you just want to swap the bearings I use Simply Bearings although their website takes some navigating...(they are probably 1/4" balls in the rear hub)

https://simplybearings.co.uk/shop/produ ... A0QAvD_BwE
(cheaper to get a bigger pack...eg 50)

How many speeds do you currently have on the bike? The diagram shows HG splines so 11 speeds max? Is this the version you have?
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RecumbentRide
Posts: 234
Joined: 27 Jul 2012, 9:11pm

Re: SRAM MTH-506 R hub, query RE bearings & hubs

Post by RecumbentRide »

Yes that was the only schematic I could find which is missing much vital information. This is the hub I have and I've got a 12 speed SRAM cassette working very nicely.
As regards the BikeInn sales page, yes I saw that yesterday but it's showing a schematic of front and rear hub not what's actually being sold so very confusing but it looks like they are just selling the core.

Essentially I know I can get a core but then I'd also need bearings (no idea what size) and a cone (no idea where to get a replacement) and by the time I've bought these and the Freehub Body Removal tool I'd be close to what I'd have to pay for a new hub. I can rebuild the wheel myself so may just get a new hub as it's less hassle.
Nessie23
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Re: SRAM MTH-506 R hub, query RE bearings & hubs

Post by Nessie23 »

When buying bearings it is worth paying attention to the Grade. The grading takes account of uniformity of size, roundness and minimising defects such as pitting. The smaller the Grade No. the better the quality. Eg G25 is better than G100. Most ‘stock’ ball bearings are G100+. I have been informed a good quality bike hub should have G25 but no need to go any lower. Also advisable not to mix and match ball bearings and replace all at the same time from the same new batch/packet.
Search “1/4” inch ball bearing G25” and you will find numerous options. A rear hub usually has 9 x 1/4” balls in each side so you need a minimum of 18.
RecumbentRide
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Re: SRAM MTH-506 R hub, query RE bearings & hubs

Post by RecumbentRide »

Thank you for your reply. I'm not sure if you saw my last message in time but I'm going to limp along with the current wheel/hub as best I can and donate the wheelset to a community cycle workshop when I've built a better quality wheelset. It was a cheap as chips SRAM hub wheelset that came with the bike so I'll be glad to get rid.
gregoryoftours
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Re: SRAM MTH-506 R hub, query RE bearings & hubs

Post by gregoryoftours »

Decent ball bearings are pretty cheap so it might be worth fitting some in the meantime anyway. 9 x 1/4" balls in each side is quite common but both size and number can vary so it's best to just remove the ones you've got, measure them and count the number in each side.

There are advantages and disadvantages to both types of bearing, cup & cone and cartridge. Cup and cone are serviceable and better designed for taking the forces in a bike wheel (side loads etc). Cones are replaceable and readily available (if Shimano), but often not the cups. Replacement cones can be expensive too. Good ball bearings are cheap.

Cartridge bearings can be a real pig to remove if they've corroded into place at all. The type that are used in hubs aren't as mechanically suitable as cup and cone for the loads, but in usage this doesn't seem to be too much of an issue. Good quality cartridge bearings are quite expensive. If you can't read the info on them to order more then you might have to remove them to measure depth, which will likely destroy them as you have to apply force to the inner part of the bearing.

If you want to keep hubs going for a long time I'd get ones that have good availability of parts, and that you can work on yourself. Often it's not economically viable for a bike shop to replace all of the bearings/freehub in a rear wheel, assuming they can even get the parts. Preventative maintenance and fairly regular checking can save a lot of money particularly for hubs. Cup and cone are better in this regard.
Last edited by gregoryoftours on 9 Apr 2021, 3:46pm, edited 7 times in total.
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531colin
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Re: SRAM MTH-506 R hub, query RE bearings & hubs

Post by 531colin »

Why does everybody always want to replace the ball bearings?
The wearing surface area of the balls is HUGE.
The smallest wearing area is the cone, because the balls make almost point contact; the second smallest area is the cup.
Just bung it all back together with lots of decent grease, set the bearing preload critically viewtopic.php?f=5&t=143125&start=15 and ride. Its possible that the bearing will wear itself back into reasonable condition; you may need to re-adjust.
EDIT excellent piece here viewtopic.php?f=5&t=145114&start=30 complete with pictures of cones worn though the case hardening....they really are toast then.
Last edited by 531colin on 9 Apr 2021, 3:45pm, edited 1 time in total.
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531colin
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Re: SRAM MTH-506 R hub, query RE bearings & hubs

Post by 531colin »

RecumbentRide wrote: 8 Apr 2021, 10:35pm ......... I imagine cartridge offers a lot of advantages.......
To the manufacturer, rather than the end user.
Cheap as chips to buy, just press it in and off you go. No setting the preload, no complex tooling.
However, the bearings are made for use in indoor machinery at high revs; very different to low revs on a bike out in the weather.
There is not enough grease in them, and its high temperature grease, not sticky stuff with corrosion inhibitors.
Cartridge bearings in a bike are always too small for the load, as the parts sizes were set when there was no option except making the bearing an integral part of the structure.
The preload on your cartridge bearing varies depending on the fit when its pressed in and also in hubs depending on the spoke tension because spoke tension distorts the hub shell.
Still, never mind, you can flog them as "sealed bearings" which the user thinks means "keeps the water out" when in fact it means "no user serviceable parts in here"
zenitb
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Re: SRAM MTH-506 R hub, query RE bearings & hubs

Post by zenitb »

RecumbentRide wrote: 9 Apr 2021, 11:50am Yes that was the only schematic I could find which is missing much vital information. ......

Essentially I know I can get a core but then I'd also need bearings (no idea what size) and a cone (no idea where to get a replacement)

...
Ok .. I think one of your issues you have identifying parts is that you probably don't actually have an SRAM hub :-) Sounds a strange comment I know but bear with me......

My Specialized Stumpjumper proudly boasts an "SRAM" MT-746 rear hub. After a bit of poking around it transpires this is actually a FORMULA DHT148 hub with some SRAM branding painted on it.
Spot the difference...
Spot the difference...
I came to the conclusion that the "SRAM GX" groupset I thought I had bought is actually farmed out by SRAM to other companies to make .. making them dependent on a load of 3rd parties for the overall quality of the result. This is in contrast to the way Shimano work where a Shimano hub is actually ... made by Shimano.

Googling "hi lo hub" the internet seems to be saying its possibly a Formula DC38 although no one actully seems to know for sure ... this may the MTB version. (Really SRAM should say what your hub actually is ...:-( )
Formula DC38
Formula DC38
formula catalogue ..https://www.formulahubs.com/product.php?t=37
EDIT or maybe the DC20LW/22 ?
Formula DC20LW
Formula DC20LW
Formula DC22
Formula DC22
Welcome to the world of SRAM OEM branding BTW :-)
RecumbentRide
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Re: SRAM MTH-506 R hub, query RE bearings & hubs

Post by RecumbentRide »

Well I'll be buying Shimano for my next set of hubs and though I'd like to try the cartridge bearing option Shimano don't seem to offer this so I'll be stuck with C&C for now. AFAIK re-greasing the hubs once a year (which I've never previously done) should give me a long hub life regardless of bearing type.

I've already spent too much time trying to find solutions for my existing MTH-506R hub, add on the cost of new components and postage it just isn't worth it. For the time being I've stuffed the hub bearings with grease and I've put it all back together.
set the bearing preload critically


What exactly does this mean? Is it a good idea to allow a very small amount of play when the hub is in hand because when the wheel is put back in the frame and the QR is tightened it all tightens up again?
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531colin
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Re: SRAM MTH-506 R hub, query RE bearings & hubs

Post by 531colin »

RecumbentRide wrote: 10 Apr 2021, 12:38am Well I'll be buying Shimano for my next set of hubs and though I'd like to try the cartridge bearing option Shimano don't seem to offer this so I'll be stuck with C&C for now. AFAIK re-greasing the hubs once a year (which I've never previously done) should give me a long hub life regardless of bearing type.

I've already spent too much time trying to find solutions for my existing MTH-506R hub, add on the cost of new components and postage it just isn't worth it. For the time being I've stuffed the hub bearings with grease and I've put it all back together.
set the bearing preload critically


What exactly does this mean? Is it a good idea to allow a very small amount of play when the hub is in hand because when the wheel is put back in the frame and the QR is tightened it all tightens up again?
Exactly that. The thread I linked explains all about setting the bearing preload and regular greasing. I grease my XTs every year, and I have never worn one out. Don't pressure wash, don't ride in the sea. Semi fluid grease in the driveside keeps the freewheel lubricated, they can dry out if you use regular grease that side.
RecumbentRide
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Re: SRAM MTH-506 R hub, query RE bearings & hubs

Post by RecumbentRide »

I can find nowhere in this thread viewtopic.php?f=5&t=143125&start=15 that actually explains what is meant by "bearing preload". Yes it's mentioned 6 times on the first page of the thread but it's assumed the reader knows what it means i.e. when adjusting/reassembling the hub bearings.

If you can actually point out where it's explained then I'll eat my cycling cap :shock:
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531colin
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Re: SRAM MTH-506 R hub, query RE bearings & hubs

Post by 531colin »

You are probably right! Its too easy to assume "everybody knows....."
The "preload" is the compressive force on the bearing which is there all the time, before service loads are imposed, and during use.
You need "just enough" preload so that you can't wobble the rim when the wheel is mounted in the bike.
If you set up the hub like that when its out of the bike, and then put it in the bike and tighten the Q/R, you are putting an enormous load on the (relatively small) contact area. (Because the Q/R compresses the axle). This quickly results in the case hardening getting worn away on the cones, as in the other thread.
Note that hubs with cassette bearings aren't (usually?) provided with means for adjustment of bearing preload.
RecumbentRide
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Re: SRAM MTH-506 R hub, query RE bearings & hubs

Post by RecumbentRide »

531colin wrote: 10 Apr 2021, 10:30am You are probably right! Its too easy to assume "everybody knows....."
The "preload" is the compressive force on the bearing which is there all the time, before service loads are imposed, and during use.
You need "just enough" preload so that you can't wobble the rim when the wheel is mounted in the bike.
If you set up the hub like that when its out of the bike, and then put it in the bike and tighten the Q/R, you are putting an enormous load on the (relatively small) contact area. (Because the Q/R compresses the axle). This quickly results in the case hardening getting worn away on the cones, as in the other thread.
Note that hubs with cassette bearings aren't (usually?) provided with means for adjustment of bearing preload.
Thank you Colin :)

Even though I know what preload is the idea of it when adjusting hubs didn't make sense to me, hence my question. As you pointed out when you return the wheel to the frame extra load is added. From what I can tell, and you've got more knowledge here, do you think it makes sense to have very, very slight play before fitting the wheel or try and not have any at all?

I read your second link and you mentioned how you've taken delivery of new wheels/hubs and then proceeded to add extra grease. You also mentioned how costly, time consuming and sometimes impossible it is to try and source cones & cups. This is undoubtedly my experience and have gotten fed up of Googling. It's beginning to make sealed bearings look like a better alternative!
RecumbentRide
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Re: SRAM MTH-506 R hub, query RE bearings & hubs

Post by RecumbentRide »

zenitb wrote: 9 Apr 2021, 4:26pm
RecumbentRide wrote: 9 Apr 2021, 11:50am Yes that was the only schematic I could find which is missing much vital information. ......

Essentially I know I can get a core but then I'd also need bearings (no idea what size) and a cone (no idea where to get a replacement)

...
Ok .. I think one of your issues you have identifying parts is that you probably don't actually have an SRAM hub :-) Sounds a strange comment I know but bear with me......

My Specialized Stumpjumper proudly boasts an "SRAM" MT-746 rear hub. After a bit of poking around it transpires this is actually a FORMULA DHT148 hub with some SRAM branding painted on it.
MT746.JPG
I came to the conclusion that the "SRAM GX" groupset I thought I had bought is actually farmed out by SRAM to other companies to make .. making them dependent on a load of 3rd parties for the overall quality of the result. This is in contrast to the way Shimano work where a Shimano hub is actually ... made by Shimano.

Googling "hi lo hub" the internet seems to be saying its possibly a Formula DC38 although no one actully seems to know for sure ... this may the MTB version. (Really SRAM should say what your hub actually is ...:-( )

DC38.JPG
formula catalogue ..https://www.formulahubs.com/product.php?t=37
EDIT or maybe the DC20LW/22 ?
DC20.JPG
DC22.JPG
Welcome to the world of SRAM OEM branding BTW :-)

These look like the cheap as chips hubs you see on pre-built wheels for sale on Ebay. Originally when I was trying to source 406 wheels for my commuter I looked at getting one of these Chinese wheelset imports but the thought of fitting crap to my bike put me off the idea. So I've now learnt to build my own wheels. Time consuming and expensive compared to the Chinese solution but the alternative was too horrifying.
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