Mazda Motorsport SUB question
 

I've got a set of the MMD SUB lifters and need to get shims for them. I've read 2 different things and am not sure which is correct. I know you either use 5.5mm or 6mm lash caps (from supertech) and they can either go on the stem of the valve or the stem of the lifter. I have seen it mentioned that some shims won't fit over the valve stems because the part of the valve stem that sticks out of the retainer is possible short.

So which is it 5.5mm or 6.0mm and on the lifter or on the valve.

For the Supertech buckets, the 5.5 caps sit on the lifter itself (upside down) and the 6mm caps sit on the end of the valve. The lifter has a 5.5mm stem and the valve is 6mm obviously. The 5.5mm caps are less of a hassle because you don't have to be worried about interference between the shim and the lifter. If you put 6mm caps on the valve, you have to be sure that the cap is sitting on the tip of the valve and not touching the retainer or Bad Things(TM) happen. Not sure what size the MMD lifter stems are but that's an easy thing for you to check.

Thanks. I think the supertech lifter stems being 5.5mm is what started my confusion. I'll check the diameter when I get home.

MMD lifters are around 5.56mm. Wonder if I can just toss them in the lathe and turn them all down to 5.5mm. Seems easy enough...

$20 says they're 5.5mm nominal.

I have a set of new MMD solid lifters, and a whole stack of 5.5mm and 6mm shim caps. I'll check for you in the morning if the 5.5mm shims fit fine... I hadn't tested as I assumed they did.

I run two shims per valve due to the smaller base circle cams... a 6mm on the valve stem and a 5.5 on the solid lifter. The 6mm shims all had to be machined so they don't touch the retainers.

Thanks guys. If I can run the 5.5s I'll have a bit more peace of mind.

I run Mazdaspeed lifters and super tech 6mm caps on the valves. They don't touch the keepers, the NB keepers have a groove around the top that they fit nicely into. Been running this setup for a little over a year I think with no issues.

The lifter stem to lash cap can be a very tight fit. I had a hard time getting them off of some of the stems. Some will fall right off when a lifter goes in or out of the bore. It really sucks to install the camshaft and find out the cap is floating around between the stem and inside lifter wall.

A bit of oil on them stops them falling off. Plus if they do the lifter clearances will be out.

Stem of lifter I measure as 5.56mm too. My '5.5mm' caps measure at 5.565mm ID. Maybe it's a standard sizing. I'll call and ask my shim supplier as I need to order some soon.

So the 5.5mm supertech caps fit on the MMD lifters?

Yes, and a steady slow hand [Insert Mom joke].

Spoke to my shim supplier. There are two sizes they do (not supertech) 5.5mm and 5.6mm. He said the 5.5mm shim caps are pretty much exactly 5.5mm ID and won't fit on. He said to run the 5.6mm shims and they will be fine. If loose install with some grease to stop them dropping off.

I can't help you with the Supertech sizing. You'll have to call them.

With some more reading I found this. https://forum.miata.net/vb/showthread.php?t=567672. Looks like I need 6mm shims, or throw the shims in a lathe (lol). Just need to be sure there is no retainer to shim interference

If you are unsure and want to put the issue to rest, just order one or two and do a trial fit. Once you are comfortable with how it all goes together, order what you need to finish it. When I set mine up, I ended up ordering caps on a few occasions until I was completely comfortable with the whole process of setting them up.

I'll do that. Apparently cutting down the stem on the lathe is actually a thing. Maybe I'll just do that.

The lifters are hardened but you'll be able to trim them down on the lathe with a carbide easy enough. You only have to take off a small amount so you won't go through all of the hardened layer but it's not ideal. I think it's better to run 5.6mm shims or 6mm shims on the valve. I have to run both for my engine.

With the 6mm caps on the valves, you need to make sure the cap shims are a low profile shim so they don't hit the collets. My shim provider has two profiles with the low profile only 2mm or so which should clear the collets. Last time I rebuilt the head I did have to sand a couple of the shims down for better collet clearance as my valves had also been machined and some had more clearance than others, It only takes 30 seconds or so on some 400 grit sand paper to drop a few thou.

I stick some wet and dry paper to a sheet of glass with some oil, then just circle the shim on the paper with a finger. You can easily take off up to 5 thou off the top to get tolerances tweaked but you need to make sure they stay level. Sanding the bottom the shim is even faster as the surface area is next to nothing, so you can take off 1mm or so without any issue, plus it's not so critical to get perfectly level.

I'll order a 6mm supertech shim to fit. Hopefully will be getting my head/block back this week, i think it will all make a lot more sense with the parts in front of me.

Here are the options:

https://cimg3.ibsrv.net/gimg/www.mia...326cb169c7.jpg

Awesome thanks. Looks like i can only get 5.6mm shims from AUS. So i might be going on the valve.

http://www.precisionshims.com.au/

Don't buy them out of 5.56 shims cause I need some! I'll actually have a whole stack left over from my head build.

Yup, thats what i found. I'll shoot them an email.

I called them earlier this morning... They have 5.6mm shims in stock and can ship them next day (plus overnight to me). I assume they'll ship to the US. If not you can use me as a freight forwarder.

I'll be ordering mine early next week after I have mounted all the valves and measured clearances.

Cool. I'll see what they can do, and maybe have you forward. Thanks for the help.

FYI I'm pretty sure Nial has the middle option. Don't be stupid, if your shims are on a lathe you're doing something wrong.

Lifters would be on the lathe :)

odd. Does that mean he has the 5.5mm shims?

I've got the packages from his shims at work, I'll double check tomorrow. I have 1 left from his build, since I measured 15/16 correct, and I have a bunch of unlabeled ones from Eddie's car and a few from an Elise, but I don't know what diameter they are.

Cool thanks. I can always just buy one for testing.

What I meant by this was that a "5.5mm" lifter stem that measure 5.56mm will almost certainly accept a "5.5mm" lash cap. These aren't so esoteric that someone makes a 5.5 and someone else makes a 5.6. On all the SUB setups I've done I've always set them up using Supertech LC55 caps (5.5mm). I'm sure you can find reference to someone running Mazdacomp lifters and LC55 Supertech shims. Ordering 5.6mm shims from overseas is silly IMO.

Alternatively, "search noob":

https://www.miataturbo.net/engine-pe...60/#post667694

Supertech 5.5mm shim does not fit on the lifter stem. So if anyone needs a single .8 5.5mm shim let me know :)

6mm shims on the valve for me it is.

The 5.6mm ahims fit nice. Precision Shims can suply up to 5mm shim height too which means I only need to run one shim rather than the two previously.

$9AUS per shim. - GST and USD conversion would place them around $6US each plus shipping.

Quote from precision was ~140 shipped. I'll stick with the supertech 6mm. They should fit on my stock valves just fine.

Color me surprised.

It was very close. And I didn't test all the shims. But it just kind of rolled around like it was about to fit on, but wouldn't slip on.

0.06mm won't slip fit regardless of how much persuasion is used! It's amazing that after 25 years of miata / mx5 development and use in motorsport these issues aren't widely known.

Eh, it kinda was a known issue. The reason I only bought a single shim was because I thought it might not fit.

I looked at the stock valves that I'm using and the 6.0mm shims should work just fine on top of the valve. If I need to change things down the road so be it. I can always toss the lifters in the lathe, but thats not needed right now.

I can't run 6mm shims on my RB26 intakes valves because they sit so close to the top of the retainer. That's what you get for running oddball stuff I suppose. The previous valves had been machined to fit the Mazda valve cotters but because I bought nitrided Supertechs my lathe cutters just bounce off them. This means I have to run the Nissan valve cotters which have the 'D' locator a few mm higher on the cotter.

Anyway, bigger 5.6mm shims work better anyway. I now have 10 days to get this head back together before my next event.

Is that the difference between the Supertech SUB Lifters (5.5 lash caps used on lifter bucket) and the MMD SUB Solid lifters (6mm caps on valve)?


I was curious why there where $100 price differences floating around.

One is built by supertech the other by Maruhahaha.

You can purchase the MMD / Maruha solid lifters individually which is handy if ever you damage a couple like I did due to valve float.

My engine is back up and running now with the 5.6mm shim caps. I have a whole stack of 5.6mm shims spare around the 1.5 - 2mm sizing if anyone needs a few for sizing.

My head is still at the machine shop. I'd like to get it back this week so I can order shims and have it back together by the weekend after.

The supertech shims are super short, i'm amazed that they could interfere with valve retainers. Maybe non stock valves or something. The "hangover" is super small.

It only took me 4 days to get the head rebuilt. I ordered 4 x 3mm shims from Precision overnight, built the head the next night and measured tolerances. Ordered the required shims the following day and received them all by lunch the next. Excellent service!

The Precision shims have a long base which is good for me due to the thickness of the shims I need which run up to around 4mm. I'm not sure I'd like that sizing sitting on a small amount of the stem, but I suppose they can't really go anywhere. The old shims that sat on the valves were very short.

here is a video of the engine idling, with a few quick revs testing the 949racing twin. It's running even more lumpy now with the lightened flywheel.

Vroom, lump, lump, lump, lump

Sounds serious.

Just to reconfirm - I have the MMD SUBs and I ordered the supertech 5.5mm caps. **They absolutely did not fit.** I had to trim down the stem diameter on the SUBs to get the lash caps to fit and it was a massive pain. I didn't give one enough clearance and the cap actually shattered when I was checking lash.

I spoke with Bill at Miataroadster and the guys at MMD and no-one seemed to be aware of the issue. :cry:

This all happened last year. Wish I'd seen this thread earlier so I could have given you the heads up. At least you only ordered one shim.

All the mazda subs I messed with got 5.5mm caps they are a tight fit but usually a punch and a strike of the hammer gets them on and a second to be absolutely sure they are seated.

Good info guys. Seeing soot shatter a cap. Makes me not want to do the Twibs method.

Maybe I'll call supertech and see what they can do about 5.6mm shims. But I doubt anything reasonably priced.

Either way, 6mm shims are known to work on the valves if needed.

How did he shatter a cap?

also iv has issues where there isn't enough stem height and the 6mm cap touches the keepers. i was in a bind once and ran the 6mm upside down on the posts of the lifters and that worked out for some time without issue. i wouldn't recommend it, but sometimes you gotta make it happen.

I tried this - I actually pushed the cap onto the stem with just some of my weight behind it and it shattered. No hammer needed, and I'm a slim (170/6'1") guy. Trying to fit a 5.56mm slightly tapered post - yes, I measured and some were that large :vash: - into a 5.54mm cap gets you bad things. The caps are extremely hard, brittle steel, so there's no give, just break.

edit - I might even still have a SUB with half of a shattered lash cap stuck on it. I'll try and grab a photo later today.

Wishing I had seen this before buying MS subs a few months ago. Should have bought from 949. Guess I'll be buying shims from Australia since I am not using OEM valves. Thanks for the great info!

SUBs CAN come out
 

Sorry, but yes they can. I ingested a screw or something, it got caught by the closing valve, the (Precision) shim floated out as the valve stopped and the bucket kept going. 180 degrees later the lobe comes around, jams the shim by the edge that is supposed to sit over the stem, and presto, I have a valve that won't close, held open by an amount roughly equal to the depth of the recess for the head of the stem.

The biggest mystery is where did the nut/screw/whatever come from? All the usual suspects checked out ok, the engine has never run without an air cleaner ...

The up side was that the valves got reseated, and no damage occurred. Given the big overlap in my engine, I was lucky to escape without piston or valve damage.

That would occur with any shim though. It's not ideal if you ingest anything into an engine let alone something metallic. I think you were very lucky to just drop a shim.

So about half the shims supertech sent me measure out to 6.42mm in diameter instead of 6mm. They are sitting on the valve. Should I be worried about them coming off somehow?

My gut tells me the answer is no, you would need an ingestion of something to prevent the valve closing to cause that (as happened to me). That is not a scientific opinion. I would email Supertech, or even Skype them if they have a freecall number (1800 here).

Supertech says not to run it. No idea what happened. But something got screwed up somewhere.

Did you buy your shims directly from supertech? I'll be getting some very soon as well to use with the MMD lifters I have. I'll be putting it on the top of the valve stem which people are reporting it measures 6mm.

They were drop shipped to me from supertech. The sealed parts bag has LC-60 on it. Which means 6mm shim. But they aren't 6mm shims.

Someone fucked up somewhere.

They are probably ok as some of my older shims were fairly loose, although probably less than 0.5mm gap. It would be hard to loose them off the valve stem unless something else jammed it up first.

I'd be concerned with them chattering or moving on the valve stem and damaging either the valve stem or the shim itself. I'm not sure if that can happen or not but if you have ever seen extreme slow motion video of a high reving valve train its a bit disturbing how everything moves like jelly and bounces all over the place.

Although they appear to have struggled to package shims correctly, I probably trust them when it comes to valve train things. And if they say not to run them I'm not going to.