elwood

iTrader: (1)

The Mazda mounts (whether the OEM or racing ones) are designed to allow the engine to move in both directions -- compression and rebound. When you put a bolt through the mount, the rebound is totally shorted out. When you're under high torque, you effectively have a solid mount on one side of the engine.

I've seen this thread before. While I'm sure many people have used hockey pucks, I think Mazda's design is much better.

If you're hell bent on using hockey pucks, realize that a soft joint like that will require you to use some sort of locking feature, or the nut won't stay on. Use double nuts, or a castle nut with cotter pin, or locktite, . . . or something.

PercentSevenC

You're right. I realized that after I posted, but it was too late to edit. My mistake.

I worried about that, too, at first. Here's the thing, though: there's a hockey puck on both sides of the engine. The energy not absorbed during the rebound on one side is absorbed by the other side in the form of compression. So it's still quite smooth. Seriously, I've used both and the hockey pucks feel very similar to the Mazda competition mounts, but at a fraction of the cost.

Very true. I'm using double nuts.

Jeff20B

iTrader: (13)

Here is the brand of pucks that went into percent's REPU and my bro's red FB.

Uh oh. The one on the left isn't an official NHL puck. I meant the one on the right.

The stock looking mounts on the far left are competitions. You can tell by the double paint lines. Stock mounts have only one line or nothing. Also you can physically tell the difference by squeezing the mount and trying to rock one end left to right. Stockers are pretty easy but these competitions don't move. In the middle are what the basic hardware looks like and on the right we see the finished product. Very easy to make and even easier on your wallet.

Lastly we see it installed. The aluminum plate is 1/4" thick so there is no need for a stack of washers to get engine tilt just right. It just sits at the right height like it was made for our cars. Cost was like five bucks.

Jeff20B

iTrader: (13)

Some specs I forgot. The bolts are coarse thread 3" long x 3/8" diamter (9/16" head) with a 2" unthreaded section and 1" of thread. Grade 8 or higher. It has six - marks on the head. Very common bolt.

The big washers are actually the OEM washers from the OEM motor mounts.

The lock washers can either be standard or OEM from the motor mounts as well.

The nuts are just regular NC 3/8". I torque the first one down until the rubber just starts to buldge. Then it seems to run out of thread as it hits the unthreaded section of the bolt. Perfect amount of torque. I then add the second nut and counter tighten together as elwood suggested. No need for any other more elaborate locking schemes on a project like this.

Oh one last thing on drill bit sizes. I use a common 3/8 bit on the steel and aluminum plates. The hockey pucks require a slightly bigger bit. I use 21/64 which works out perfectly but 3/8 will do. Just realize the pucks will tend to grip the bolt making installation just a bit less easy than with the extra clearance.

DoomedXtance

alot of us vw mk2 guys use this trick too. its kinda weird I feel dumb under a rotary and I am just shocked at the amount of stuff that can translate over the culture/ mechanical gap.

Jeff20B

iTrader: (13)

Yeah, especially when you put a rotary in an air cooled VW.

I've got a set of hockey pucks going into my FB tomorrow!

DoomedXtance

aside from puttin my motor in and hoping it runs I may put some pucks under it as well. Havent done it yet as there are a great many things on my to do list

Glazedham42

iTrader: (4)

Back from the dead. Came across this whilst doing my own research today. Someone REALLY needs to archive this. Jeff's last 3 posts are great stuff. Really great stuff. Nice work Mr. 20B. Hopefully this will get archived, as it is well worthy for sure.

Glazedham42

iTrader: (4)

By the way, for any of you guys having trouble finding pucks I found them online here for $1.99 each. They are official NHL licensed pucks, although I doubt that matters much for this application.

http://www.hockeymonkey.com/oficehocpuc.html

Jeezus

iTrader: (4)

Just wanted to pass along some little tidbits:

to find the center of a circle, use a ruler or something straight and put a marker on
one side. Holding the ruler on one side of the puck (or circle), move it back and forth,
so it makes a parenthesis shape. Do that for the 4 corners, and where the
parenthesis touch, draw a line through them. X marks the spot


It looks weird doing it in MSPaint, but it works every time.

Jeff20B

iTrader: (13)

Nice info. I just eyeballed where to drill the hole. I'm getting pretty good at it.

Glazedham42

iTrader: (4)

Jeff,

Two questions for you:

1) What is the thickness of the bottom steel plate you used? I don't see a thickness mentioned in the thread anywhere.

2) Is it necessary to use square sandwich plates or could I use round instead? The only reason I ask is that I found some nice round aluminum 1/4" thick discs from McMaster Carr. They are part # 9035K33 on mcmaster.com. I could just buy them and drill a hole in the middle and be done. Do the sandwich plates need to be square in order to properly distribute the load against the engine brace, or would round be okay? I am thinking of using 3-1/4" diameter aluminum discs. This would give me 1/8" overlap all the way around the puck, since it is 3" in diameter.

Let me know your thoughts. Thanks for the great writeup!

Jamie

trochoid

iTrader: (6)

Round is fine, perhaps even preferred. That little bit of square corner sticking out won't make any difference in strength or spreading out the load. Round also has a much neater finished look.

PercentSevenC

What that means is that you can be sure that they're the correct composition and durometer. The NHL has very specific rules about the specs for the officially licensed ones.

When we did mine, we used two 1/8" plates, but they were a bit short so we added some washers to get them to the correct height. The ones in Jeff's pictures have one 1/8" plate and one 1/4" plate, which gets the height pretty close.

No, they don't need to be square. In fact, depending on your setup, square plates may or may not even clear everything. I know Jeff had to grind the corners off at least one of his sets.

Jeff20B

iTrader: (13)

1) 1/8"

2) Square was easier to cut (less time consuming). You're thinking too much. Must be an engineer thing lol. A 1/8" lip sounds perfect. Only the middle of the puck buldges slightly when compressed.

I used aluminum because it was available, lighter than 1/4" steel, and didn't require extra washers to get the total thickness up to where it needed to be.

Glazedham42

iTrader: (4)

Thanks for the info Jeff! Your mark will now be left on my car in a second area (ignition system being the first).

zaridar

iTrader: (3)

I prefer using a tape measure... measure the width... divide by 2..... measure that distance from one side.... then do the same 90 degrees away from the first... make an X....

hmmmmm.....

zaridar

iTrader: (3)

http://atkinsrotary.com/store/catalo...p-1-c-641.html

I got these.... i like them... i know they are more money... i think when i purchased them they were 49 each...

Jingkun

iTrader: (4)

Thats not a bad price for the comp mounts, I'd probably go that route if I hadn't bought the steel back when I was fabbing up my cat delete pipe. That was 6 months ago, still looking for those damn pucks in texas.

zaridar

iTrader: (3)

i like them! much stiffer compared to stock. you can even tell by hand... and also not really obnoxious when driving...