Stripped the thread on Shimano R9170 lever bleed port

[Marchaugh]

So I was cleaning my bike yesterday and also cleaned up the front disc caliper as it was a bit sticky. After cleaning I noticed that the front brake didn't really work, maybe I let some air in when I extended the caliper pistons.
So I went to bleed it, something I have done a few times before, and undid the bleed screw and started to attach the bleed adapter. It was getting tightish but I just thought I'd give it one last tweak, and then it spun easily. Fearing the worst I undid it to check and my fears were confirmed. I must have overtighten the adaptor and the thread had stripped. I almost cried when I realised what I had done.
iI tried inserting the bleed screw with plenty of PTFE tape round it but it just spun. In the end I screwed it in best I could and sealed it on with some silicon as I have a day off and a ride planned for tomorrow.
I looked online and found a few others that have had the same problem as apparently the thread in the lever is a very soft material.
The brake works a bit but you can tell there is a fair amount of air in there. To get my brake working temporarily for tomorrow is it possible to bleed the brake using the bleed nipple on the caliper only? Using the same principle but with the bike upside down?
For the long term does anyone know of a way of repairing this? I heard people have managed to get a replacement under warranty from Shimano for this problem, does anyone know how to contact Shimano about this? I'm not very keen to go through the shop where I got the bike as I can see them going 'oh you shouldn't have done it yourself you should have let us do it'
I would be very grateful of any suggestions or help on either of the questions.
Thanks in advance...

 

[Cycleops]

Worth trying Shimano but jeez they’re not cheap are they. Which is why I always adhere to the KISS philosophy.

 

[fossyant]

Oh poop.

 

[iluvmybike]

You'd never get a warranty claim on that - it's not a manufacturing fault

 

[si_c]

If you've definitely stripped the thread on the lever and not on the bleed adapter then it's suck it up and buy a new lever time.

 

[wafter]

IIRC Shimano's importer is Madison, so it might be worth contacting them directly with the usual "I love your products but was extremely disappointed by... now can't use the bike... not the quality I've come to expect from Shimano... blah, blah" approach.

I'm guessing the port is in major part of the lever that can't easily be replaced; only other solution I can think of is getting a thread insert fitted but I'm not sure how feasible this would be as I'm not familiar with the levers.

Good luck!

 

[Outlaw Hobbs]

Having recently installed and bled a Shimano Ultegra brake system I can really empathise - what a carp design that bleed port is. The rubber hood gets in the way making the business of removing and replacing the cap or bleed funnel cleanly without cross threading/stripping it extremely difficult. If you can determine the thread size it might be possible to drill out the port and tap the hole using a tap of the next size up and then use a short bolt with a tiny ‘0’ ring to replace the cap. It’s important to use the correct size drill bit to match the tap and you can look up the information on engineering websites.

 

[Marchaugh]

Tried my idea of bleeding the brakes from the bleed nipple on the caliper but that didn't work at all, pumping the brake lever like you normally would simply pumped all the oil out! Plus my silicon seal around the bleed screw started leaking. So I removed all the silicon, bled the brakes like normal (there seems to be enough thread for the funnel adapter to grab but not the short bleed screw) and then put a lot of PTFE tape on the screw and pushed it back in. I then spent quite a while degreasing the area with alcohol and then sealed it with hot glue. The brake worked fine and I was able to get through my ride yesterday without any trouble.

 

[Marchaugh]

IIRC Shimano's importer is Madison, so it might be worth contacting them directly with the usual "I love your products but was extremely disappointed by... now can't use the bike... not the quality I've come to expect from Shimano... blah, blah" approach.

I'm guessing the port is in major part of the lever that can't easily be replaced; only other solution I can think of is getting a thread insert fitted but I'm not sure how feasible this would be as I'm not familiar with the levers.

Good luck!

Yes OK thanks, I will try contacting them and see what they say. I was thinking of using similar wording myself

Having recently installed and bled a Shimano Ultegra brake system I can really empathise - what a carp design that bleed port is. The rubber hood gets in the way making the business of removing and replacing the cap or bleed funnel cleanly without cross threading/stripping it extremely difficult. If you can determine the thread size it might be possible to drill out the port and tap the hole using a tap of the next size up and then use a short bolt with a tiny ‘0’ ring to replace the cap. It’s important to use the correct size drill bit to match the tap and you can look up the information on engineering websites.

Yes I think its crazy that such an important thread for maintenance is made of plastic. I think the fact that my funnel adapter was made of metal didn't help things at all.
I was thinking about re-tapping the hole and using a bigger bolt but the only issue I though of was that you won't be able to use the funnel adapter to bleed the brakes which may cause issues.

 

[tomknight]

Just done the same thing myself, seeing where the warranty goes to but not likely.

Liking the glue it in place idea, it's only for my winter bike. Such a stupid design fault plastic with an alu soft bleed screw.

 

[T.M.H.N.E.T]

Madness... That's your front brake, the most important brake on a bicycle!

 

[MichaelW2]

The kind of mechanical that can end a tour. Better to screw this up at home or better yet, at someone elses home. Thanks for the Public Service Announcement.

 

[confusedcyclist]

Same thing happened to me, despite being a metal thread on MTB callipers, it's so small, it didn't take much to cock-up, so I do sympathise. Nothing to be done about it, other than learn from your mistake. It's just another reason to use proper shop tools, or stick with mechanical disc brakes if you can find them. Not that any of that helps you now! I like the temporary fix that OP showed

 

[iluvmybike]

I can't believe how you can cock something up like that and then even consider trying a warranty claim - it is no wonder manufacturers kick back when they have to deal with things like that. Just accept you were a bit ham-fisted and take the hit. You won't do it again! I wouldn't trust my well-being to the 'temporary fix' either...

 

[Marchaugh]

Just done the same thing myself, seeing where the warranty goes to but not likely.

Liking the glue it in place idea, it's only for my winter bike. Such a stupid design fault plastic with an alu soft bleed screw.

I contacted the Specialized concept store where I got my venge from who sent the lever off to Shimano who said they would replace it FOC, and after about a 3 month wait (because of covid and stuff) it has arrived!