by the way, you hage a pic that shows the height difference of bryans mounts, why is that?

http://dave.newbern.org/gallery/view...ame=rx7&id=aea

 

by the way, you hage a pic that shows the height difference of bryans mounts, why is that?

 

It's the arm the bolts to the engine that differs between the mounts. One is cast iron and the other is aluminum by the looks of it, and the iron one is thicker at the damper end, making the entire package thicker. The dmpeners seem to be equal in height, about 2.5 inches.

 

"ask, and ye shall receive"

 

Ok, gimme.

 

I thought about emailing him about it.. another aluminum cup would look a lot better than a home depot washer..

 

how hard is the urethane that Rotor motorsports is using? I was thinking of going with 60 shore A, which is similar to a tire. or 80 which is harder yet, but i don't want to go with anything harder than I need to have.
heck, it's $54 for 6" of urethane from McMaster-Carr (almost $10 per inch ). so if it doesn't work, i'll just order the stock mounts, and if it does i'll save nearly $200 for something more fun

 

It's definitely firmer than that. A lot closer to the hockey pucks. If you had a similar type of aluminum cup to shield them, you could probably just stack 3 pucks on top of each other and make mounts for $8 plus the cost of a bolt.

 

RotorSports Racing, not Rotor motorsports, get the name right. Rotor motorsports doesn't even exist anymore.

 

I was even thinking about that when I was typing it. damn rotor motorsports and their bad business ethics anyway.

 

Yeah, since Bryan's my mechanic I feel obligated to make the distinction. No problem though.

And yep, those scoundrels over at Rotor motorsports caused alot of grief and another reason why the confusion of names should be corrected.

Garrett

 

If your car is going to be street driven, I highly recommend purchasing the stock ones. I've driven a FD with the rotor sports racing mounts and they transmit way too much vibration at low rpms. Might as well get solid alum mounts.

I had a few broken motor mounts and decided to make my own. I was planning to a mount similar to design as the rotor sports racing mounts but all my designs require a soild shaft though the urethane. This would transmit vibration.
If you are super cheap you can use a FC mount with some modifications. I took a FC mount which are relatvely cheap and abundent. Modified the broken FD bracket with a mill and drill a center hole for the stud. Then slightly cut the FC metal cup around the mount on each side so the retaining strap would fit.
I've tested the mount and there is much less vibration than the rotor sports. I can't comment on the durability yet as it's only been a few months. I think I have some pictures of it completed.

Btw, the drivers side motor mounts have been redesigned by mazda. The newer ones are steel rather than alum. and the rubber seems beefier.

-Jeff

 

i think i'm gonna try making my own. material is yet to be decided. the way i look at it is that i have much to gain and only a little bit to lose by at least attempting to make my own. if they transmit too much vibration or otherwise suck, i'll order new OEM ones and be out $100 max. thanks for everyone's help.

i'll let you know how it turns out too

 

ok, well i decided to order some urethane from McMaster-Carr (http://www.mcmaster.com/ ). I went with 80 shore A polyurethane. part number: 8784K98


pics of my old drivers mount:
http://wave.prohosting.com/isuposs/p...eak-29_jpg.htm
http://wave.prohosting.com/isuposs/p...eak-74_jpg.htm

pics of my new mounts:
http://wave.prohosting.com/isuposs/p...eak-73_jpg.htm
http://wave.prohosting.com/isuposs/p...eak-72_jpg.htm
http://wave.prohosting.com/isuposs/p...eak-71_jpg.htm

Impressions:
I only have a couple hundred (highway) miles on these mounts, so i can't comment too much. they definately stiffen up shifting. people always said how engine torque braces stiffened up shifting and I thought they were crazy, i realize that i am wrong!!

I can feel the starter engage through my steering wheel!! dont't know if that's good or bad

I get some vibration at idle and if it kinda lugs from a start.

Future:
I'm gonna make a few changes in the next couple of weeks. first, i'm going to try what nebernd did and see if that reduces vibrations. I also need to add some spacers on the top between the steel belt and the motor mount. kinda hard to explain, but maybe i'll get under there and take some pics this weekend.

Overall, so far, I'd recommend it if you can stand a little vibration. it cost me all of $60 plus a few 3/8" bolts and hardware. Definately a do-able mod if you have access to a bandsaw, wire wheel, and a drill (a lathe would be best for drilling the hole, but a drill or drill press would work)

 

NICE JOB! Thanks for the info, time for me to make my own mounts.

 

ISU do you have any tips for doing the bushings on the frontend...? sorry I was flipping through your pics!
Looks good to me! (engine bushings)
-R

 

I used a press. it took around 4 tons of pressure to get those little buggers moving then much less once they were started. Probably not something that I would want to do by hand. But if you don't have access to a large press, one of those bottle jack presses could probably do the trick. To remove the old bushings, you need various "circles" to press against. For some of the bushings we pushed on the bushings while keeping the suspension component stationary, and for others we pressed on the suspension component while keeping the bushing stationary. For instance, anytime you have two bushings on the same axis, you can't hardly fit the press in between the two bushings; ie upper and lower front a-arms, part of the rear upper a-arm, and the differential mount. So this is where you get a round slug (small enough to fit through the suspension eye, but big enough to press on the metal ring around the bushing) and place it below the bushing, Then with a hollow pipe-shaped piece, placed on the shoulder of the a-arm, press the a-arm downward while the bushing pops out the top. This is of course with the majority of the a-arm below the press and out of the way. I know that's probably confusing as heck, but i'll try to make a diagram sometime. the nylon ones went in much easier.

If you were thinking about saving some money and making bushings, read on.
I made my bushings modeled similar to jim's bushings. I ordered the materials, once again from McMaster-Carr. the nylon was pretty cheap. If i were to do it again, i probably would leave the little shoulder off and just center the bushing when i pressed it in (like i did on the diff bushings). that could have cut down on the lathe time considerably. also, using a more machining friendly metal than SS would be a bonus. I'm thinking of brass due to it's decent corrosion resistance and machinability (if that's a word).

now I can say that I know why Jim/N-tech get so much for these bushings, they are a pain to make

 

don't laugh

 

great info on the motor mounts ISUposs
, looks like I may use your concept

one question, why do you even need to use the metal bands (or steel belts) anymore?

 

another question, cant you just use another (but much thinner cut) 'waffer' of the same material and use that on the bottom, where new nebernd puts the hocky puck? this accounts for the 'pull' vibration, correct?

for example, use a 3" section as the main mount (like you did), then use a 1" section underneath, between the mount bolt and frame.

or is 80 shore still to tough for the pull vibration dampening?

nebernd....any more updates on your hocky puck mod?

 

i don't know if the bands are still required, i just put them in because they aren't really in the way and they offer me a little piece of mind.


that's what i'm going to try. I have a 1" thick hunk of uerethane left over that i'll make the bottom piece out of. i'm going to take a hole saw and cut out a couple of 1-1.5" circles. i'll probably keep them under an inch in length. I don't want too much hanging out in case it deforms too much.

 

great idea, let me know how it goes, if it works out for you ...tight drivetrain but no vibration...then I will try it too.

Did you have to buy more than 6", or was 6" enough for the 2 mounts and and a spare 1"....in other words, how long did you have to make the mounts?

 

i just bought 6" of it. the mounts were roughly 2.1" and 2.3" IIRC.

 

very cool, I'll hit mcmastercar.com and pick up rod of it..... so you think 80 a is the way to go, no comment on weather you would have went harder or softer?

 

i'll let you know after this weekend.