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Housing Lapping and Coating Question

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Old Jul 1, 2015 | 02:40 PM
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Housing Lapping and Coating Question

So I am considering having my 12A housings lapped. I know they are originally nitride and not sure if I can find someone in Houston to do nitriding although I have not really looked. There is a company that does coatings that suggested doing a fluoropolymer composite coating with phenolic resin that attracts oil...

Anyone familiar with coating lapped housings and is this recommended? This is the same coating used on engine bearings.
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Old Jul 1, 2015 | 03:14 PM
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I did find a place that nitrides in Houston for $1.22 per pound. He said he would do a 24 hour gas nitriding process. Will this work?
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Old Jul 1, 2015 | 03:31 PM
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Martin S.
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check with pettit, they do resurfacing
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Old Jul 1, 2015 | 03:49 PM
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Stupid idea. Leave them alone.
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Old Jul 1, 2015 | 04:41 PM
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Chip Motorsports or Mazdatrix
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Old Jul 1, 2015 | 08:43 PM
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Originally Posted by Jeff20B
Stupid idea. Leave them alone.
Well, they are just not perfectly flat and I thought if I'm going to spend nearly $1000 on a rebuild kit, shouldn't I make sure the irons are true and flat?

Why do you think it is not a good idea?

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Old Jul 1, 2015 | 10:40 PM
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The wear resistance is in the nitrided surface, when the housings are lapped most of it is taken off. Then the housing and side seals don't last long.

What's that polymer resin coating generally used for? Pistons?
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Old Jul 2, 2015 | 08:38 AM
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Originally Posted by j_tso
The wear resistance is in the nitrided surface, when the housings are lapped most of it is taken off. Then the housing and side seals don't last long.

What's that polymer resin coating generally used for? Pistons?
Typically bearings... Which in my opinion is not the same as having a side seal scraping...

I did find a place that will nitride for $1.22 per pound in Houston.
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Old Jul 2, 2015 | 09:39 AM
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if you nitride the housings you will need to remove all the brass press fit oil galley plugs and install pipe plugs in their place. you will also need to replace all the freeze plugs. save yourself the headache and plan for that otherwise they will leak and cause you all sorts of problems.

obviously you do this all after it has been treated.

the price is a little high but not like most cities have multiple nitriding facilities. last set i had done at nitrex for about $100 for 3 irons that is about 120lbs. generally the more you do the less the price is though, initially they wanted a minimum order of like 7 complete iron sets for $500. i would have done that instead if i had the time to actually lap that many irons. the price is usually dependent on how large their ovens are, they wanted me to buy a whole oven slot which holds about 1000lbs but they managed to piggyback my order in with someone else's.


also keep in mind that most commercially available nitriding is VERY dirty, or at least with my last experience it was. there was excess nitride left coating all the surfaces that i had to scrub off and it still shed into the oil after assembly. but this may have also been because i rushed them to complete it.

Last edited by RotaryEvolution; Jul 2, 2015 at 09:52 AM.
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