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Engimuneer Extraordinaire
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Discussion Starter · #1 ·
Just in the shopping phase right now, but wanted to know what everyone preferred and why. I'm def. going poly on the engine, just not sure about the tranny.
 

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Engimuneer Extraordinaire
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232 Posts
Discussion Starter · #3 ·
Nothing against it. I just know they offer both, and figured I'd ask for some opinions. I know it'd help stiffen the drivetrain a bit, just worried it might make it a little to stiff.
 

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FFCobra Fanatic
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12,975 Posts
I'm with Frank. What ever is used on the motor should be used on the tranny. You can have a problem of the softer mount moveing more then the firmer poly mounts if mixxed.
Just repalced a rubber mount that had broken due to poly mounts used on the engine but not tranny.
Don't mix and match mount materials.
 

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Engimuneer Extraordinaire
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232 Posts
Discussion Starter · #6 ·
YAY, POLY FOR EVERYONE!!!!!!!!! Decision made, thanks everyone
 

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Premium Member
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11,853 Posts
In short the only rule is whatever the motor is, the trans should be the same or softer. For example, solid motor with poly trans is fine but not the reverse. HTH, Cheers Richard.
 

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Slacker Extraordinaire
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I went solid emgine with rubber tranny. Didn't want to overstress the driveline but need to keep the air cleaner stable
 

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566 Posts
Not sure why any one would replace rubber with rubber. The Poly mounts are resistant to rotting and pretty hard to break. I was told the bell housing is very close to the top of the trans tunnel and to use the most firm if not solid mounts avail. I have not yet put my engine in so I cant say how true that is. I will replace my rubber mounts with poly mounts even though they appear to be in xlnt shape.

Henry
 

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Engimuneer Extraordinaire
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232 Posts
Discussion Starter · #10 ·
I hadn't considered solid mounts at all. I assume it makes the vehicle feel a lot more vibrations. Any real benefit?
 

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Living Large
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Poly, Poly

Feels fine, no movement.

Trent
 

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FFCobra Craftsman
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2,238 Posts
Solid motor & trans. (Maximum Motorsports Units)..... tried the poly (Energy Suspension), but got a weird shift in the chassis going from 2nd to 3rd above 6K (it's a race car so it does get punished a touch), would pull to one side as motor shifted/torqued, very uncomforting at times .... went solid all around eliminated this issue completly, never going back ... Pat
 

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Engimuneer Extraordinaire
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232 Posts
Discussion Starter · #13 ·
If I go with the solid alum diff mounts for the IRS housing & solid motor mounts, then is it still ok for the tranny to be either? Since they are coupled with just the driveshaft, might not matter, just asking the questions.
 

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FFCobra Craftsman
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6,103 Posts
Personally, unless it is primarily a track car, I would stay away from a solid mount - will transmit 100% of vibration into the car. Poly is a good performance compromise. Again, just my opinion.
 

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FFCobra Craftsman
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24,747 Posts
You can't believe how collapsed mounts (so metal to metal)ruin the sound of a Lexus inside the car. There is no way I'd solid mount an engine or trans except in a race only car.
 

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FFCobra Fanatic
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12,975 Posts
JhnBrackett, may want to consider not useing solid motor or trany mounts for a street car. definetlly don't want solid motor but rubber trans mount. With the motor and tranny bolted together,they need to move together.
If useing solid motor but rubber tranny mounts. The tail stock of the tranny will want to move and this may place stress on the engines mounts. Could have a cracking situation at some time on the engine mounts?
Best to keep all mounts the same. Both solid or both rubber. Just useing the poly mounts over stock rubber mounts you can feel an increase in engine vibration. Solids transmit a lot more and not sure you would be happy with them on a driver car thats not a race car.
whatever you choose. Keep both engine and tranny the same.
 

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Geez guys.....I've always had solid mounts in my car and it's been fine. Lots of guys here run them. There's a little more vibration with my 408 stroker than there was with a 302 but still no big deal. I run a poly trans mount but I had solid before with no issues either.
 

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Engimuneer Extraordinaire
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232 Posts
Discussion Starter · #18 ·
Wurf: I think your answer is the general consensus I've found from this & other posts. I have not heard a single person using solid mounts that felt it added much more vibration than the poly's.
 

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I'd not use rubber motor mounts if given the option for polys. I've had solid Moroso motor mounts and rubber tranny mounts for 8 seasons/ 21K miles on my MKI. I have been in other cars with rubber and/or poly mounts and feel minimal vibration difference especially when the power is on hard. I actually felt my FFR rode better than one of the CSX cars I rode in. SPF's always felt like a smoother cruising ride to me (I have live axle) but again, once the pedal's down there was still so much vibration through the seat! I've found no more than normal bolt loosening around the car. Headers were the main culprits but that was cured with wire lock bolts years ago. I do go over all the bolts in my car each season but many other guys wrench each year and we all find something loose here and there. I believe the solid mounts are contributors to the car's ability to track dead straight when jumped on down low. Throttle response on a roll is instantaneous ...immediate like the rear is tied to the pedal. If the car does vibrate a bit more I may simply not notice because it also smells of exhaust, it's hot, it's noisy as hell but of course that's why we love these cars! Anyway...just another point of view.

GEEZE...Did I misread this Thread Topic ! I was thinking Motor Mounts. Sorry Bud.

[ November 02, 2007, 09:06 AM: Message edited by: JAM1775 ]
 
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