Grinding when pedalling backwards

[Mountie]

Hey Chaps,

Was wondering if anyone has suffered with what sounds like dirt grinding when pedalling backwards? We have very dry conditions at the minute and I’m not sure if it’s just dirt of a motor bearing going. I’ve removed cranks and cleaned everything I can but haven’t removed spider yet. Anyone have a fix for this?

Thanks in advance

 

[Mountie]

Nobody suffered this, I feel so special lol

 

[outerlimits]

It’s a design fault imo.
@Specialized Rider Care have not responded to my last post on what I think may be the problem.
Small rocks and debris get caught between the inner and outer shaft causing them to lock Together in some instances. I don’t know if I’m missing a seal or not.
I have to take the drive side spider off and dig the crap out with a sewing needle when I have problems.
Some pics of before and after cleaning.

 

[Mountie]

That totally sucks, weird that I haven’t had this issue for the 2000 kms I’ve done until now. It does sound like a slight squeak which would make sense with what your explaining. Worried it will damage the seals and the motor will suffer water ingress.

Thanks

 

[Mountie]

Question, why only when we are pedalling backwards?

 

[outerlimits]

Question, why only when we are pedalling backwards?

Because the inner and outer shaft turn together when pedaling forwards.
A sprag clutch is used to disconnect so you can freewheel.
I believe the reason one should never direct any sort of water spray towards the motor drive side is because of water ingress at this point.
I also believe that derbies in this void would wear the internal bearing seal. And also allow water into the sprag clutch. Thus causing corrosion of the bearings and or clutch and these components sticking and becoming rough in operation.
I always lay the bike drive side down after washing or a wet ride to help drain water from this small void. It is such a narrow void that it would hold onto moisture and attract contaminates.

I have seen pics of either Shimano or Bosch motor with a wider void at this point which would let any crap out more easily.

 

[outerlimits]

Some tear down pics from Brose

 

[Mountie]

Thanks awesome information

 

[DanDilla]

I had this too for 2000km... But I only felt the grind when spinning backwards by hand and it was barely to hear when the bike was standing.
Then it started screaming one morning after 100m and was completely dead.
Got a new one from specialized, warranty exchange.

If you’re out of warranty - better clean it out!

 

[Mountie]

I had this too for 2000km... But I only felt the grind when spinning backwards by hand and it was barely to hear when the bike was standing.
Then it started screaming one morning after 100m and was completely dead.
Got a new one from specialized, warranty exchange.

If you’re out of warranty - better clean it out!

I’m still in warranty but thought I’d clean it out anyway I think I’m at 2000kms at the minute too. 90 mins of cleaning it out with a cable tie yay still has a tiny bit of noise just not sure i can get much more out. It didn’t have much but a tiny bit of dirt in it anyway.

 

[Mountie]

That sounds internal for sure, still under warranty?

 

[khorn]

That surely sounds like the big needle bearing gone south and like other have said, if you still have warranty get it in. If no warranty you can try to to put your bike down on the non drive side and let some thin oil seep down. However if the oil get past the bearing it can destroy other internals. Anyway if no warranty the motor will eventually die no matter what.

Karsten

 

[outerlimits]

Wow and that’s the 2019 motor with the same void. Thought they may have done something different with the new Mag motor.

 

[Bearing Man]

I have posted this before but can't find it now so here goes again. When pedalling backwards the only bearings moving that are not moving when you pedal forwards are the central sprag bearing and the crank needle roller bearing. Both these bearings fail. The sprag bearing can start to break up and the retaining spring gets caught between the sprags and the housing, or it can just start to rust and gum up.
The needle roller bearing suffers from water ingress, rusts and dries out (See pic). We repair many of these at www.performancelinebearings.com Sadly, left too long it wrecks the bearing surface of the crank shaft and although we have a limited supply of good second hand ones, it's much better not to let it get to that point because you can't buy these parts new.

 

[Mountie]

I have posted this before but can't find it now so here goes again. When pedalling backwards the only bearings moving that are not moving when you pedal forwards are the central sprag bearing and the crank needle roller bearing. Both these bearings fail. The sprag bearing can start to break up and the retaining spring gets caught between the sprags and the housing, or it can just start to rust and gum up.
The needle roller bearing suffers from water ingress, rusts and dries out (See pic). We repair many of these at www.performancelinebearings.com Sadly, left too long it wrecks the bearing surface of the crank shaft and although we have a limited supply of good second hand ones, it's much better not to let it get to that point because you can't buy these parts new.

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Thank you for the information I have only 4 or so months of warranty I have spoken with my retailer, who is excellent, and they will look at this Monday. Question, do you put a better quality bearing or seal in the Brose so it stops this happening and do you see the same motors back twice for this repair?

 

[Bearing Man]

We replace the plastic caged sprag bearing with a steel cage sprag bearing to stop the cage failures. As for the needle roller bearings, Brose use a needle bearing designed with two internal rubber seals, designed to keep the grease in, but they don't keep the water out. This bearing is currently unobtainable so we use two thinner needle roller bearings side by side to give the same bearing load area and we have also sourced an external double lip seal to fit in front of these bearings to ensure a much better sealing system.We have not seen any motors back with our bearings or seals failing.

 

[Mountie]

We replace the plastic caged sprag bearing with a steel cage sprag bearing to stop the cage failures. As for the needle roller bearings, Brose use a needle bearing designed with two internal rubber seals, designed to keep the grease in, but they don't keep the water out. This bearing is currently unobtainable so we use two thinner needle roller bearings side by side to give the same bearing load area and we have also sourced an external double lip seal to fit in front of these bearings to ensure a much better sealing system.We have not seen any motors back with our bearings or seals failing.

Is it easy to fit your kit with the new type of bearings or best to ship a motor to you for the repairs, I’m in North America.

 

[Bearing Man]

Today 9/06/19 we have just finished filming a new video on how to overhaul a Brose motor. It should be edited and on-line within the next week, you guys can then see how it's done

 

[Bearing Man]

We don't have to, we have added a water tight seal, you'll see it in the video.

 

[Mountie]

This is the noise I’m gettin

Today 9/06/19 we have just finished filming a new video on how to overhaul a Brose motor. It should be edited and on-line within the next week, you guys can then see how it's done

thats fantastic!!

 

[Mountie]

No they are releasing the video so you can install their bearing and seal kit.

 

[Mountie]

Specialized are changing the motor out on my 18 quite happy. Does anyone know the part numbers on the Brose s id like to make sure I don’t get a T in error?

Cheers

 

[Bearing Man]

This is a shot of the bearings we removed from the Brose motor we overhauled for the new video! Made for an interesting job!

 

[Mountie]

This is a shot of the bearings we removed from the Brose motor we overhauled for the new video! Made for an interesting job!
View attachment 14910

Hmm That’s a big job! Is the performance better now?

 

[Bearing Man]

It is now

 

[Slowroller]

Yikes! Those are some crunchy bearings

 

[outerlimits]

@Bearing Man
It surprises me Brose don’t make their motors more water proof. It appears they would of had many returns in the last few years because of water ingress.
It appears you have found a solution to the problem, and well done.
The cost to make the motors more waterproof would be minimal to Brose, so you would think they would act.
Maybe someone from Spesh could get Brose to up their game. It’s affecting the rep of Specialized after all. @Specialized Rider Care

 

[Bearing Man]

@Bearing Man
It surprises me Brose don’t make their motors more water proof. It appears they would of had many returns in the last few years because of water ingress.
It appears you have found a solution to the problem, and well done.
The cost to make the motors more waterproof would be minimal to Brose, so you would think they would act.
Maybe someone from Spesh could get Brose to up their game. It’s affecting the rep of Specialized after all. @Specialized Rider Care

Most of the motor manufacturers are upping their game, Brose have added extra seals and their "S" motors are reported to be IP56. The new Gen 3 Bosch again is much better protected with dedicated outer seals.
It should be kept in mind that the largest markets and the markets these motors were designed for was road bikes. It was not until the bike manufacturers started putting these motors into mountain bikes that they started to see these issues.
Sadly, Companies the size of Brose, Bosch, Yamaha etc. can't just change something overnight. It has to be long term tested, production facilities changed, new certification applied for etc, etc.

I guess what I am saying is, hang in there, better motors are coming and I will be out of business .

 

[Mountie]

Most of the motor manufacturers are upping their game, Brose have added extra seals and their "S" motors are reported to be IP56. The new Gen 3 Bosch again is much better protected with dedicated outer seals.
It should be kept in mind that the largest markets and the markets these motors were designed for was road bikes. It was not until the bike manufacturers started putting these motors into mountain bikes that they started to see these issues.
Sadly, Companies the size of Brose, Bosch, Yamaha etc. can't just change something overnight. It has to be long term tested, production facilities changed, new certification applied for etc, etc.

I guess what I am saying is, hang in there, better motors are coming and I will be out of business .

Mine is an s about 18 months old 1900kms

 

[Mountie]

Do you have a link to the Brose kit?

Thanks,

I think they are all separate bearings at the minute.