Drum brake wheel cylinder doesn't mate with brake line

xraydave

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Dec 8, 2015
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East Texas
While installing my OMU lift, I went ahead and replaced the brakes.( shoes, spring kits and drums) while attempting to replace the wheel cylinder, I couldn’t get the brake line screwed into the new cylinder correctly. I had plenty of slack on the brake line and it wasn’t crossed threaded. I ended up putting the original wheel cylinder back in. My question is: What are the possibility of the threads being different on the cylinder I received from O’Reillys?

View attachment 136149
 
According to Mr. Blaine thru the years Jeep changed something with the wheel cylinder bore hole threads? You can even purchase a new Mopar wheel cylinder and have the same problem with hard brake line threads not mating with wheel cylinder. I was told you have to get it finger started (which won't be much!) then use your line-wrench to fully tighten...no way you can fully tighten with fingers. It feels as if the wheel cylinder bore hole is too small or the thread count has changed and won't allow the brake line to mate?
 
Believe I would put a thread guage on the brake line fitting; find a corresponding tap and run it into the cylinder to smooth the thread fit and then be sure to clean the cylinder of any chips should the process produce any.
 
Supposedly it's just a REALLY tight fit to the point you have to use a line-wrench. When I can't get a good finger start to insure I'm seating correctly I'm pretty reluctant to wrench it. Ha! This might be one of those times to rebuild your existing wheel cylinder if the housing is not pitted...just another avenue to consider.
 
Believe I would put a thread guage on the brake line fitting; find a corresponding tap and run it into the cylinder to smooth the thread fit and then be sure to clean the cylinder of any chips should the process produce any.
Doing that you may get a piece of metal in the brake cylinders.
 
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Thanks for your response "be sure to clean the cylinder of any chips should the process produce any." Concerned me also.
Thread carefully here. Sorry bad pun. If you take a good look at those threads you will see the seat area for the double flare on the end of your brake line. Even a bottoming tap will run into that seat and then you will never get the flare to seal. At least that is a very real possibility. Get a thread gauge and make sure both the cylinder and flare fitting match. Threads on a flare fitting are straight, not tapered like a pipe fitting so xray dave is correct to be concerned if the line does not thread in easily.

B
 
Thread carefully here. Sorry bad pun. If you take a good look at those threads you will see the seat area for the double flare on the end of your brake line. Even a bottoming tap will run into that seat and then you will never get the flare to seal. At least that is a very real possibility. Get a thread gauge and make sure both the cylinder and flare fitting match. Threads on a flare fitting are straight, not tapered like a pipe fitting so xray dave is correct to be concerned if the line does not thread in easily.

B
Never occurred to me there was a flare. Thanks for your comment.
 
What did you finally end up doing? It is a year later and I am in the same boat. I got a new wheel cylinder from Oreiley's and it didn't fit.
 
Mr. Blaine informed me that you will not really get much of a finger start to ensure that you are not cross-threading. I did my best to finger start (won't be much at all!) then had to use line wrench to fully tighten. All went well and glad I didn't cross thread fitting on brake hard line.
 
What did you finally end up doing? It is a year later and I am in the same boat. I got a new wheel cylinder from Oreiley's and it didn't fit.
Thanks man. unfortunately, I screwed up the line now, so I ordered a pre-bent one from Rock Auto. When it comes in, I will do as you did. Have a great weekend.
 
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