Where can I find some of these to replace the factory rubber mounts. The car is an 88 10th AE with a 20b. I already haver the k2rd adapter kit but they still incorporate the original rubber mounts.

 

It may sound ghetto, but hockey pucks do a good job. If you want something made out of metal it can be done, but it's not the greatest thing for the street. I believe that both http://www.mazdatrix and http://www.srx7.com sell "stiffer than stock" mounts.

 

http://www.mazdatrix.com/mounts.htm
http://www.shaneracing.com/sr86susp.html

 

actually a hockey puck might be better than the cut aluminum dowel that www.srx7.com sells. you dont want to transfer the engines vibrations to the chassis unless you have too

mike

 

The hockey puck method works really well. Hockey pucks are alot stiffer than the stock mounts, but they still abosrb vibration from the engine well. I was thinking of buying some and selling them as "competition" motor mounts. I could buy 2 hyockey pucks, some nuts and bolts, drill a few holes, and charge $100 for $4 in parts and 20 seconds of labor.

 

special stanley cup mounts

mike

 

Hockey pucks sound like cool idea, but I already ordered a set from srx7. Solid mounts are not THAT bad; considering no sound deadening material, 500lb. front springs, delrin bushings etc. This isn't a daily driver, nor a road trip car, so it's no big deal. As far as transfering vibrations through the chassis, it's not like the unibody will develop cracks, just my teeth.

 

You just don't want to put a "powered by CCM" stciker on your car.

 

It's not the immediate increase of noise that's bad - it's the "V" in "NVH" that's bad.&nbsp Compliant engine mounts are designed to damp vibrations that would normally transmit through the chassis.&nbsp Vibrations are basically oscillations that stress and strain metal (brackets).&nbsp Solid engine mounts are designed with a safety factor to minimize failure from all the stress cycling.&nbsp Now, I'm not a mechanical engineer, so I don't know what the formulas to calculate this safety factor; for all we know, the stock mounts could be "good enough".

A 500hp+ 20B is going to produce some serious torque, and solid engine mounts are going to have to keep the engine from spinning in the engine bay?&nbsp That's a scary proposition with solid engine mounts...



-Ted

 

...especially ones made from hockey pucks.... I don't know how resilient a hockey puck is, but It's gonna have to stand up to several thousand vibrations per minute just from the engine running... (I don't think it's THAT resilient...)

 

actually the problem with the stock mounts an a 3 rotor are the same as with a 2 rotor. the passenger side one breaks? how many fc motors have you taken out with good motor mounts? 80% of the time they are bad anyway. what you are looking for in a motor mount is something that will hold the torque, without vibrating the chassis. the force on the passenger side mount is in the up direction, when you move from a stop, you can through bolt a hockey puck, or a piece of aluminum.

mike
running 20b fc

 

why not due what the V8 guys do and weld a chain from the motor to the subframe?

 

When I used to work on old Chevy's before I was enlightened, I put together some wicked engines. A 454 big block making well over 600 ft./lbs of torque could not be held down with normal mounts. We made a "torque strap" out of a steel rod with a left and right thread rod end combo. It worked great, but then again, there was plenty of room for such a contraption. I don't plan on having that much room with a 3 rotor and single turbo. However, I am planning on adding a strut tower brace, much like one from Racing Beat, that ties into the firewall in two locations and also bolts to the top of the engine, essentially triangulating the mounting positions for the engine. The only bad things I see happening are improved throttle response and a more rigid front end seeing as how the engine itself has become an integral part of the chassis. I have no worries that this will be strong enough.

 

I made a torque strap for my 12A for $6... $2 for some cable and eyelets, and $4 for an "Emergency Brake Cable Adjuster" to set the pre-load on the cable. Put one end on the front housing and the other end on the strut tower.

Worked EXCELLENT! No additional vibies, yet no more extreme drivetrain slop.

 

using the rotary as a stuctural part of the chassis is not a good idea either. the only thing that keeps the plates from moving around are the tension bolts, and dowel pins. why do the high hp cars break dowel pins? why does mazda keep movong the motor mount point backwards? again look what the factory did when they wanted to use the engine as a structural member on the 787b. not only does it have a thick aluminum plate on the bottom of the engine, but a carbon fiber one on top too. why did they go to all that trouble when you want a race car to be as light and simple as possible?

mike

 

That's an interesting point. I never heard anyone mention that.

 

i had a cutomer who built off road motorcycles for honda back in the 80's, he made a big deal out of "stupid" little things like motor mounts, and the weight distribution of the engine (cams are heavy...) how much power it takes to pump coolant around the engine (port the water jackets anyone?) stuff that makes sense but maybe is taken for granted.

mike

 

There will be a thick aluminum plate on the bottom of this 20b. It will be a dry sump system which calls for a flat bottom and I am going to make it extra thick. It will become a sheer support plate, as long as those little oil pan bolts do their job. We may end up tapping the holes to accomodate slightly larger bolts to handle a little more torque, hopefully making the plate a little more effective. Don't think I can do anything on the topside, though you never know. Besides, this setup will see nowhere near the forces the 787 saw, and the engine, even though it is tied into the chassis, will not realistally provide much structural rigidityor catastrophic forces from the chassis (unless a catastrophic wreck). As for adding any weight, none. I don't see anything complex about this and anyways, most modern race cars are the farthest things from simple. What exactly are the main causes of dowell pin failures? I know they do sometimes happen, but never dealt with one or known anyone who has.

 

High boost and/or detonation can lead to cracking of the side housings in the dowel pin area. I had the rear housing of my motor crack at the dowel pin right near the oil filter a few months ago. I didn't hear any detonation. So I think it was just from too much boost. I think I hit over 20 PSI on pump gas. Luckily the rear housing was the only damage. Here's a picture of the damage:

 

If that was from sheer torque being transmitted through the engine, the dowel would have tried to rip upwards. That cracking is downwards, as if the rotor housing was trying to force itself circular (as under detonation).

I'm convinced that Mazda's moving the engine mounts around has only to do with the chassis design. In the FC, a front mount could not be used because it would interfere with the steering rack, so the mounts were moved to the intermediate housing. In the FD, the powerplant frame doesn't hold the end of the transmission up so much as steady it - the weight of the engine and transmission is more or less balanced on the motor mounts, so they are moved rearward to the back of the engine.

 

I'm not exactly sure as to what happened. I was just glad that the motor didn't seize from the big oil leak. If it helps, here's an image of the face of the housing:

 

Crap that dowel pin failure is nasty!


-Ted

 

peejay, do you honestly believe that Mazda would have kept the front motor mount on the later higher powered engines? I wouldn't trust the front cover mount with much over 250HP.

When I do my 20B, I'll be able to use the front motor mounts, but I'd rather use the stock located 20B ones. Maybe I'll use all four? Could it hurt?

 

We could add it to your old "Hall of Failures."

 

peejay if you read the literature they moved to the fc mounts to cure a resonance at 3500?rpms (i've had 13+ 1st gens and never noticed it), and then the gave a similar reason for the fd. then they have bulletins on how to fix the fd mounts, to keep them from making noise.

mike