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[NacCat]

Im replacing all the brake components on my 1994 trailer. I have a new master cylinder cap to replace the old messed up one and when I took off the old master cylinder I found that the threads that the cap threads into are rusted. I have used my thread tool from my tap and die set and it looks like the tap I need is a 3/4 ” by 20. I took it to the local mill supply and they think it is a 20 mm by 1.25. Does anyone know what the size and tread count is on the master cylinder cap? Here is what Im trying to fix.Any help would be appreciated.Thanks,Mike

[Bass Cat Boats]

They used to have a tap at the factory when we commonly worked on Atwood Mobile couplers, though no longer have that tap handy. Your coupler is pretty warped with rust and we are not sure it will easily tap and seal. You can weld that area redrill and tap, or replace the coupler and body. You have the tap so any plumbing pipe store or large hardware store should be able to help more. We searched our records and we do not have the dimension.BCB

[dbasketman]

I think it looks like standard pipe thread. 3/4 npt. but take it to the hardware store and try the cap in a pipe fitting to make sure.

[Tommy Yetts]

You just need to replace the master cyl. assy. Its not that expensive around $70.00. We have them in stock.Tommy YettsRockwall Marine

[Bass Cat Boats]

I already have a new master cylinder for the trailer and have replaced both wheel cylinders. I just need to fix the threads so I can finish this up. We dont have any hardware stores around here anymore, lowes and Home Depot took care of that. I may have to take it to a machine shop and get them weld it and re thread it. Thanks for the help. Mike

[Bass Cat Boats]

Lowes and Home Depot should be able to help.

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