R.P.M.

Now I hear that when you get an endplate (I mean the front, middle and rear iron when I say endplate) that has been worn down and has very small grooves in it from corner seals, it is possible to get them lapped to make them smooth again.



How is this lapping done?



Is it as simple as taking it to a local machinist and getting him to use a milling machine to plane the surface flat again? Or is it much more complicated than that?



Joe

YellowT2

It's kinda like that, but not with a milling machine. There is a different machine for lapping. Think of a jumbo orbital sander, it's similar to that. You want to remove a minimum amount of material, and make it as flat as possible.

C. Ludwig

Plates can be done with a mill or ground. Paul Yaw mills his first then hand laps them. I've heard of other (Jim Susko for example that do the same) Lapping is generally a higher precision process and finding places that do it can be hard. Once you find someone, unless you're in a metropolis with a facility close by, you'll have to ship the plates which throws the price benefit to new out the window. I have a high end shop just down the street and last summer we set up jigs to grind two sets of irons. We measured a brand new set of irons from the factory at an average of 12rms. The refinished, used irons were an average of an 8rms. So the surface was around 50% "smoother". Paul Yaw's site says he mills to a minimum of 15rms after hand lapping. Dimensionally we went beyond the .003" maximum recommended on one surface that was pretty rought to begin with. We ended up removing .0048". I had concerns for the oring integrity of that iron but the motor is currently being broken in with no signs of a problem. This same motor, with used, very good condition, low mileage S6 rotor housings (also street ported and exhaust ported) and all new seals made 90psi compression before it was fired. We'll check the compression again after the break in period.



In the end I spent about $200 on the setup costs for the jigs. Once that is paid for my cost to grind housings is significantly less that what Mazdatrix for example charges and I have no shipping cost.

banzaitoyota

I use a dedicated shop set up for lapping. LAPPING is all they do. If you want it done right: go to the pro's.

GTUs

will you recommend to us? how much did you paid for it? Nitrated too?



has anyone tried get lapping done at SDJ motorsports? appearently they do nitrate after lapping. I can't find anyone else does that beside SDJ.



thanks

banzaitoyota

I am not at liberty to disclose SDJ's Sources; however they are not the same as mine. I have a source for nitriding and lapping. The killer is the shipping required.

scathcart

Out of curiousity, what does nitriding cost you? Price without any special discount you receive.

When I priced it out, with the shipping there and back (out of province, I haven't found a company I trust for lapping) and cost of having all four surfaces renitrided, it was cheaper to buy all new irons... Our dollar is up, but even so, It is still quite costly.

banzaitoyota

The nitiding was $125.00 for 100lbs of material.

GTUs

I had talked to Allan auto tech recently about getting plates laped locally in our area, Barry said," no one does it around here"



where is this place you are refering to?



new irons are too costly, not everyone have access to at-cost new parts from Mazda dealers though.

GMON

I did some calling arround one day.



You can take up to 8 thousandths off total(Cant remember that for sure). Only 2 thousandtsh per plate though.



Everyone said good luck getting nitriding thats as good as factory without spending more than a new plate. Nitriding is also less than 1 thousandth so it will not replace enough material if you go more than 2 thousandths on a plate.



A lapped plate will wear quicker but if you premix you dont notice this as much.



Often the bottom of the wear mark cant be read on a dial guage becuse the point of the guage is too big. When you lapp the plate and take off 2 thousandths you will often end up with marks left that are deeper than the 2 thousandths you took off.<shrug>



Remember that 12A, gslse and 2nd gen+ engines are totally different in their lapping requirements. Water seals are different.



Racing beat Mazdatrix and Pineapple racing all provide lapping. The place that does the work for Pineapple is just down the road from them but they would not tell me who they were, obviously they are getting a deal. RB and Mazdatrix do their work in house. Pisses me off that people cant give others a hook up on places that do this stuff. We found a local place that does grinding and they can lap as well so call arround. All places said they use "Optical Grade" lapping compound in their process but are very tight lipped about it.



The absolute best solution I found to this problem is this site. http://www.jhbperformance.com/

When I called they said they could put up to 20 thousandth on a plate! Its the same coating as used on the 787. I read the paper on that engine (787)and they said they had "minimal" wear after that race which is mind blowing.



The fact that they can do housings as well as plates is kick ***.



GregW