m20b28 rotating assy pics

[ForcedFirebird]

Depending on BMW's ID clearances vs the needed oil gap tolerance, I guess they'd have to be honed.

Not necessarily. Typically iron pushrod v8's don't need honing, but I just did an LS a couple weeks ago that needed it (ally blocks tend to core shift after heat cycles).

The problem is the tolerance on the m20. Just the process of pressing can distort them enough to bugger things. They are only 2mm thick and you are shooting for a .013mm oil clearance (.0005" per side, or .001" total diameter). Too much and you lose your oil pressure.

[McGyver]

As of now, yes.

I believe I can attain the accuracy needed for them to be press and go, but feel it's best to hone just a little to dial in. With the stock bearings, I would bore .010" out of them before pressing in, just to lessen the time needed to hone. My bearings are already the size I would turn them to, so there's very little material that needs removed.

Depending on BMW's ID clearances vs the needed oil gap tolerance, I guess they'd have to be honed.

[ForcedFirebird]

Welcome back! I was gone for about 5 months moving to PA. Once I find a garage/workshop, I'm going to be getting technical with a 2.7i build.

Do your bearings need to be honed in place like the originals?

As of now, yes.

I believe I can attain the accuracy needed for them to be press and go, but feel it's best to hone just a little to dial in. With the stock bearings, I would bore .010" out of them before pressing in, just to lessen the time needed to hone. My bearings are already the size I would turn them to, so there's very little material that needs removed.

[McGyver]

Left r3v for almost 2yr, and no-one wants to talk about the interesting/technical stuff. :(

I sold several installation tools, and am now making bearings from bronze since they have been NLA (outside NOS) for over a year. I really don't forsee BMW making any more, either. Such a small market. :(

https://www.r3vlimited.com/board/for...d#post10055001

Welcome back! I was gone for about 5 months moving to PA. Once I find a garage/workshop, I'm going to be getting technical with a 2.7i build.

Do your bearings need to be honed in place like the originals?

[dvallis]

Thanks for sharing John. Awesome stuff.

[mikey.antonakakis]

Left r3v for almost 2yr, and no-one wants to talk about the interesting/technical stuff. :([/url]

I sure do want to talk about it! But I feel your pain, my build thread is super low engagement. I certainly appreciate the knowledge you've shared over the years!

[Panici]

Agreed, not boring.
People just have shorter attention spans now with the influx of media into every facet of our lives.

[It's Soda Not Pop]

Left r3v for almost 2yr, and no-one wants to talk about the interesting/technical stuff. :(

I sold several installation tools, and am now making bearings from bronze since they have been NLA (outside NOS) for over a year. I really don't forsee BMW making any more, either. Such a small market. :(

https://www.r3vlimited.com/board/for...d#post10055001

yes some of us are still interested in the technical stuff. I don't care how boring you think it might be post all of your knowledge and services.

[hasa]

I’m interested. Technical postings are best, and sharing knowledge!

[ForcedFirebird]

Left r3v for almost 2yr, and no-one wants to talk about the interesting/technical stuff. :(

I sold several installation tools, and am now making bearings from bronze since they have been NLA (outside NOS) for over a year. I really don't forsee BMW making any more, either. Such a small market. :(

https://www.r3vlimited.com/board/forum/e30-classified-forums/for-sale-wanted/parts-for-sale/10054997-m20-intermediate-bearings-upgraded#post10055001

[ForcedFirebird]

Nice, I will be watching for updates 8^)

I have had one on my watch list for a while but haven't needed it yet

May be a bit. After a lot of thought, pretty sure a tool post grinder build will come before making a stepped reamer. Might be able to pull it off in the Toolmaker surface grinder, but would be stuck using a rotating collet. I feel it would be better suited on a lathe with a post grinder. Plus I can make valve guide pilots in house with a green wheel. Purchasing carbide valve guide pilots is very expensive compared to round carbide blanks (about 150x less).

Making up a plan to make a fixture to allow this process to be done in one's garage, and rent them out to fellow m20 enthusiasts. Think if the locating dowels for the front crank seal housing and/or oil pump mount holes, then a square jig can be bolted to the block and be really close to parallel of the crank mains. I am shopping for a block boring setup, so there will be tooling and a fixture setup to pop these out in-house, but it's not along the ultimate goal of this little side project. :)

[whodwho]

Nice, I will be watching for updates 8^)

I have had one on my watch list for a while but haven't needed it yet

[ForcedFirebird]

Thanks for the ideas. Went ahead and picked up an adjustable reamer, 1.344"-1.5" ($$$) to see about "maybe" making a one-operation tool. Worst case, it will be two operations, and plan on making a squaring fixture to hold the reamer(s).

[whodwho]

Sorry yes for finishing the bearings. Would be more accurate then hand reaming but I guess you could make fixtures to hold the reamers as well.

[digger]

yeah i think he means the two bores need to be concentric, iirc the factory reaming tool was a dual sized reamer done in one op.