nzrx7racer

Hi currently rebuilding my Turbo 2 . Should i resurface all the plates ?
I heard u get better compression if they are all smooth?

IAN

iTrader: (3)

I've heard that you should resurface them. Mazdatrix does this. Some shops say its not a good idea?

I'm going to try and do mine but I live in canada and I'm trying to find someone local. No such luck.

On a side note I don't think you can lap them much due to the seal not compressing properly so you might only be able to lap them once maybe twice.

Ian Skacel
88 10th AE

rotorhead1

i have heard theories both ways.

pro lapping:

it makes the side housings FLATTER. thus a better seal, thus higher compression.

con lapping:

it removes the low friction surface that your side housings have from the factory. thus making higher friction, thus shortening engine life.

i had a set of 86 NA housings lapped with success, but the trick to this is minimal length tolerance by the E shaft. it is a set length, and if you make the side housings thinner, the block becomes shorter around the same length E shaft. that is why lapping can only be done once or maybe twice.

my 2 cents

copandengr

Resurfacing the side housings is called lapping..It is a process where a set of precisely mounted grinding stones are moved across the surface in a back and forth movement while they are turning at the same time.

The problem with lapping is two fold. One is the grooves in the housings that the sealing o rings fit into. If too much material is removed there will be an insufficient depth here. The other problem is the nitride treatment. This is a process to toughen the metal. It is NOT a "low friction" treatment. It is an anti-wear treatment. Nitriding penetrates about 3 to 7 thousandths deep. Lapping may remove metal below the depth the nitriding penetrated. If this happens the plate will wear very rapidly in use.

There is a nationwide company called Moore-McMillan Industries that will re-nitride your plates. There are several other companies no doubt. I was fortunate that Moore-McMillan had a facility about 60 miles from me. They charged 150 bucks for all three plates.

Nitriding is a very heat intensive process. Any plastic in the plates such as injector diffusers will be melted. Lapping requires all the dowel pins etc be removed so the plates can be mounted correctly and the lapping stones have a flat surface to run over.

As far as lapping, a company called LAPCO in Lake Wiley S.C. has considerable experience lapping Mazda end housings. They lapped mine and did an excellent job. Their prices are very reasonable, but shipping is costs are the pits. If memory serves me they charge about 35 to 40 bucks a surface plus a 10 dollar clean up fee. The shipping was about 70 bucks each way.