Almost everywhere I see in N/A here polyurethane is the replacement for the OE engine mounts; eg:Noltec, Banzai, Garfinkle etc.

However, in Japan I see a few companies like FEED and SuperNow offering aluminium motor mounts. What would be the pro's and cons of having aluminium motor mounts versus polyurethane ones?

 

Polyurethane is a better dampener.

Aluminum motor mounts will cause massive vibration.

 

I forgot to add that for a race/autox application solid mounts are generally preferred. Sorry if this is obvious information, just trying to answer your question.

 

https://www.rx7club.com/showthread.p...m+Motor+Mounts

 

Getting the Aluminum mounts for the same reason as Polyurethane ones; being there more stiff making less flex but to what extent.... Is it really worth it to lose the flex? Not on the streets, prob make you sterile

 

Most of the poly mounts you can buy or make yourself are PLENTY stiff enough for any street or track use. The only upside I see with aluminum mounts is that they will probably never wear out. Sometimes the passenger side poly engine mount will crack/deform/melt from the heat of the turbo(s). Retaining the heat shield usually helps with this issue.

 

As time goes by I'm thinking about just going back to OEM. I'd rather have to replace stuff like that every so often...takes some of the fun out of driving the car. If I really pushed my car then maybe, but for everyday use I'm second guessing myself, but then again I'm talking about more than just motor mounts.

 

I have solid motor mounts. I bought them from a friend a few years back when he was doing his LS1 swap. I can't remember where he originally got them (maybe Gotham). I have those mated with a Garfinkle Engine Torque Brace (and Gotham Oil Pan Brace). The car doesn't vibrate excessively. However, I won't necessarily recommend them unless you are planning to have more of a track car than a street car.

 

I actually HAVE these mounts, peoples, versus, um... ppl who don't have them or have never driven on them, and perhaps i may clear up a few misconceptions for anyone considering them.

Power transfer from the engine to the road was noticeably more "direct" since the engine doesn't rock when you press the accelerator.

I consider the poly mounts 99% solid mounts. Trust me, they're pretty solid, you won't be able to compress them, but they're by no means anything that's going to make anyone sterile nor will they be in any way "unstreetable."

My Racing Beat dual exhaust is a more aggressive mod than these mounts.

On top of my RX7.com aluminum/chromoly links and trailing arms and polyurethane differential mounts (and Banzai diff brace), the poly engine mounts made the biggest difference in reducing wheel hop.

There is a minimal increase in engine vibration at below-2000 rpm and sound coming from the solid mounts, but you'd be surprised how little it is.

Or to test the waters, so to speak, one option is to replace just *one* of the mounts with a poly mount and see what you think.

[The poly diff mounts, however, for me were just too much. They did transmit engine and diff harmonics into the cabin that exceeded my "liveability" threshhold.

I replaced them last month with brand new stock diff mounts, and the car's much quieter (good for dates so the girl duzn't think/realize ur a crazy car nut n get a headache from the noise), and the performance feels the same.]

Hopefully my experience helps.

Josh

 

also,

I don't have any oil leaking from my Pineapple FD sump with the solid mounts.

Cracking/melting/deforming of these mounts ?!?! Really, i'd like to see THAT....

Josh

 

I can't tell if you have solid aluminum or poly mounts... I have poly mounts myself and like I said they are pretty darn solid. However they do compress. Mine compressed a noticeable amount (after a couple hours) when the weight of the engine/trans was first applied after installation.

POLY engine mounts have definitely cracked or deformed in the past due to heat and stress... I've seen it happen. As I said before I seriously doubt that aluminum mounts would have any issues.

 

When it comes to modding, I'm pretty hardcore (no p/s and a/c, huge exhaust, etc) and I've never seriously considered running solid AL motor mounts. I'm happy with my poly Gotham mounts, they've given me zero problems since I installed them back in 2003.

 

I can't seem to find them on their website. Did they stop selling them? Or can someone link them to me.

I've been trying to deiced weather to go Poly or new OEM motor mounts. Mine seem a little weak and its causing oil pan leaks. I am in the process of getting BanzaiRacing's Diff brace + Oil pan brace and Aspec's tranny brace. Not sure on what to do about the motor mounts yet.

On another note, I used to have solid aluminum motor, tranny and diff mounts in my FC and it was very noticeable. The car definitely felt better response wise. But get on a bumpy highway and it just would wear you down so fast especially at high speeds .

 

http://gothamracing.com/osc/product_...019f3f5c369fc2

 

FWIW, I'm running the Noltecs and at least so far, love them. Judging from the lack of movement of my shifter, it controls engjnie/transmission movement MUCH more than my OEM mounts ever did. No more stick in a pot of jello from the shifter. But I have not sensed any increase in NVH, and I think I'm pretty sensitive on things like that. Other than reducing movement, the Noltecs feel and sound just like OEM. I'm considering a diff brace to reduce drivetrain movement at the other end, but the problem seems to be solved in the front.
I agree with Mahjik's suggestion that solid aluminum is most appropriate for track cars. But then you can't get poly in all those cool anodized colors.

 

Unfortunately the Noltecs aren't available right now, they were bought out by Whiteline and production has stopped.....you might be able to find some in stock here in the US, but from what I was told there won't be any more coming into the country for a while.

 

We have our mounts in stock.


http://www.banzai-racing.com/polyfd_motor_mounts.htm

 

I love my self-made poly sandwhich mounts. I made mine from shore 80A poly from mcmaster. Like JuicyJosh said, there is a small amount of vibration at idle and such, but it's barely noticable. The feel of poly mounts is amazing. They make shifting feel positive and more controlled.

Aluminum mounts seem foolish to me. I don't see what their benefit would be aside from durability and there could be detrimental effects.

 

I was wondering what would be involved if I didn't send you a steel bracket or the original mounts.

 

um, i just said i have the poly's ..... (??)

We have GOT to be talking about two different types of mounts here.

The poly mounts on my FD are still - after all this time - stiff as hell. They measure just as thick as when i bought them. No squishing on these bad boys...

Initial crank on engine start-up STILL violently jerks the car. Grabbing any solid part of the engine and violently shaking it shakes the whole car, but the engine does not move. Steve Kan tuning last Feb with the hood up: no humanly-perceptible engine movement. (The whole car shifted though when he let off. - That was pretty cool.) Throttle response is STILL very direct.

These poly mounts are THICK as hell, and there's a fat *** heavy metal ring running through the middle of them. These are pretty hardcore...

A LOT of us rotorheads have the poly mounts. It's not really that uncommon because they're NOT expensive, definately MUCH cheaper than new stock mounts, plus: Better throttle response and MUCH less wheel hop.

There's no way mine are going to melt. The soft stock rubber mounts are more likely to burn/melt/shoot heroin than the polyurethane mounts.

Again i'll believe it when i see it, and my guess is i'll never see it this side of a sustained engine fire. seriously...

I run poly mounts, and so do ^^^

 

Yes, sorry about that... I did miss that part in the middle of your post. I was just confused by the first sentence "I actually HAVE these mounts" when the person you were quoting was talking about moving to solid aluminum mounts.

FWIW, I was referring to the more home-made "sandwich type" poly versions. This is what I have on my car and they work great along with being affordable. However there have been a few cases where the poly section was affected by the extreme heat coming from the exhaust. (One was a local guy w/ single turbo and another I saw posted on here). They also do compress a bit... although this is really only noticeable when you install them and tighten the bolts. If you shake the engine the entire car moves, like you stated.

Maybe the more 'professional' poly mounts are stiffer and more heat resistant.

Regardless I think we are saying the same thing: Poly mounts are stiff enough for 99% of the population. I don't see any real benefits with moving to aluminum mounts.

 

All these "solid" mounts, diff braces, torque dampers, trans braces etc. make it difficult to properly tune your engine. They ALL make excessive engine "noise" and cause false knock readings. Personally I think the "give" that the rubber mounts have are a good thing, for more than one reason.

-J

 

mcmaster says their polyurethane rods have a high temp range of 171-210 deg F. If your mounts are getting that hot with the heat shield still there, then I'd think something is wrong.

 

So the stock marshmallows will silence the engine. Got it.

*Standalone* they're definately good for:

1 - Excessive engine movement which also applies stress to the other supporting driveline members
2 - Twice the rear wheel hop
3 - Less throttle response (in ANY gear, with the biggest difference being 5th gear)
4 - Accelerated wearing of the bushings, and there's a LOT of em, and they're not cheap, or easy to remove and reinstall
4 - Increased transmission and driveline shock (transmission rebuilds are not cheap either - i KNOW)
6 - Making your date think you don't know how to drive your "rice rocket" as the back end of the RX-7 hops all over the place

"excessive engine noise" confusing the knock sensor ?? are you for real ?

It's obvious you have no experience with polyurethane mounts. Or perhaps you're imagining the effects of solid engine mounts on *piston* engines.

Wait...

"They ALL make excessive engine "noise" and cause false knock readings. "

So... all of us ^^^ with poly engine mounts have mis-tuned engines in your opinion.

And ALL racing RX-7's with poly mounts and other braces are not tuned according your insight...

A lot of us have a lot of experience and work on our own cars here.

Not to a dick but

i can only imagine people reading the threads on this forum wondering what's the right and what's nonsense with people posting stuff like this.

 

Calm down there before you have a heart attack. Maybe if this forum wasn't a slap contest but a rebutal match we would have better threads than "What BOV sounds best".

WOT knock is what we care about and at WOT the engine is running smoothly and the compression that is to be occured has occured so I don't think it would affect to the degree you are mentioning. However, maybe this would be true for Alum. mounts. I was wondering because I remember paying my Noltec's like 250$ and I see that the SuperNow Alum mounts are 120$ shipped!

I guess the concensus is that Alum. is for track only applications.