Solid or Poly Body Mounts? - Team Camaro Tech
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post #1 of 26 (permalink) Old Jun 20th, 08, 07:39 AM Thread Starter
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Solid or Poly Body Mounts?

I need new body mounts and wanted some opinions on which to get and pros and cons of each. Which do you guys say to go with?
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post #2 of 26 (permalink) Old Jun 20th, 08, 09:16 AM
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Re: Solid or Poly Body Mounts?

Not too many answers...I have done lots of research on this site about it. There has been tons of threads over the years about it to learn from. I have gathered there is lots of opinions both ways. I'm gonna but Poly next week from Performance Online. Do a search, you will find lots of info. Good Luck!
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post #3 of 26 (permalink) Old Jun 20th, 08, 09:22 AM
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Re: Solid or Poly Body Mounts?

I am looking to change mine as well, but I am going to go with Solid's from DSE I think. I've read alot about theirs and they have great service and feedback on the Protouring and Lat g sites as well.

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post #4 of 26 (permalink) Old Jun 20th, 08, 09:25 AM
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Re: Solid or Poly Body Mounts?

General rule: If you intend to install SFC's in the future, then use solid mounts.
If not, use either poly or rubber.

Personally, I would not use rubber at all for body mounts. But I'm sure you will hear different opinions on this.

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post #5 of 26 (permalink) Old Jun 20th, 08, 09:28 AM
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Re: Solid or Poly Body Mounts?

What does SFC have to do with using poly or solid body mounts? I've never heard of this.

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post #6 of 26 (permalink) Old Jun 20th, 08, 09:37 AM Thread Starter
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Re: Solid or Poly Body Mounts?

I'm courios why solids too. I have Jegs SFC I will be putting on in this process.
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post #7 of 26 (permalink) Old Jun 20th, 08, 10:49 AM
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Re: Solid or Poly Body Mounts?

Quote:
Originally Posted by 6Z8RS View Post
I'm courios why solids too. I have Jegs SFC I will be putting on in this process.
By putting SFC's in, you are fixing the front subframe to the unibody. If you use poly or rubber, you allow the subframe to flex. Solids will form a rigid connection. With the flex, you are putting added stress on either the SFC's bolts or welds if welded in. You may end up with stress cracks in the welds or fatiguing the bolts.

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post #8 of 26 (permalink) Old Jun 20th, 08, 12:51 PM Thread Starter
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Re: Solid or Poly Body Mounts?

Dipren,
I understand what you are saying, but I don't see an advantage on a normal street car with around 450lb-# of torque at the wheel. With the moment taken out at the approx 3' lever arm of the connection points you are only talking about a 150 pound load to the connections. If you measured the strain of a poly at 150# neglecting the metal sleeve it needs to compress, it would be negligble. On higher rated setups I could see some advantage, but not on street cars.

I think i answered my own question. Poly!
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post #9 of 26 (permalink) Old Jun 20th, 08, 01:57 PM
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Re: Solid or Poly Body Mounts?

If going to use mainly for street cruising, go std rubber, same for suspenstion
Makes for a very pleasant ride

Use mainly for track, solid....

Rubber is fine for fast cnring thru the mountains on a trip...u dont push as quick as if one is on the track anyway....Dont let bragging rights of "I have Solid mounts/suspension" over ride a pleasurable car to drive on a trip...

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post #10 of 26 (permalink) Old Jun 20th, 08, 03:15 PM
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Re: Solid or Poly Body Mounts?

Quote:
Originally Posted by 6Z8RS View Post
Dipren,
I understand what you are saying, but I don't see an advantage on a normal street car with around 450lb-# of torque at the wheel. With the moment taken out at the approx 3' lever arm of the connection points you are only talking about a 150 pound load to the connections. If you measured the strain of a poly at 150# neglecting the metal sleeve it needs to compress, it would be negligble. On higher rated setups I could see some advantage, but not on street cars.

I think i answered my own question. Poly!
It is not just torque, it is also chassis flex. Flex over bumps, undulations, etc... Unloading the suspension, etc. If you don't want to run solid, don't weld your SFC's. Or, weld them at the rear and bolt them at the front. Even the slightest amount of deflection may lead to a failed weld.

Hear me out here, as I understand that solid mounts may cause a rougher ride than rubber. This is not true if you properly set up your suspension. Chassis flex leads to squeaks, rattles, etc. Even in modern cars, we are always in search of the stiffest chassis. The suspension is then setup to absorb the bumps in the road. Please don't take this the wrong way, but poly is a waste of time. If you don't want to run solid, ask yourself why even bother with SFC's, as you are tieing in the front subframe to the unibody...

My recommendation would be to do the following:

If you want SFC's, run solid. If you don't and you are just looking for a cruiser, just run rubber and skip the subframes. You aren't really doing anything for torsional rigidity with subframes anyhow. They are really only increasing the beam rigidity...

Nick DiPrenda
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post #11 of 26 (permalink) Old Jun 21st, 08, 05:17 AM
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Re: Solid or Poly Body Mounts?

go solid- you won't regret it. the Competition Engineering parts are cheap and work- you just need to buy some shorter bolts and large washers, which will be about $5 if you have a place that sells grade 8 hardware by the pound- i got all my body mount and suspension hardware from a place called Mills Fleet Farm, but i think there are other places that sell nuts and bolts by the pound.
i used them on my Nova- with 55lb front springs, low profile tires, and brand new rubber bushings the car was nice and tight, but had absolutely no creaks or rattles. it just rode and drove like a newer car, and i could tell there was almost no chassis flex- before the rebuild, i could feel the gap around the top of the door moving around just by driving down the road when i had my arm resting on the door with the window open. after the rebuild with the solid body mounts (but no subframe connectors), i couldn't feel any flex at all.

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post #12 of 26 (permalink) Old Jun 21st, 08, 10:41 AM
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Re: Solid or Poly Body Mounts?

Now you guys have done it! I welded up my sub frame connectors as soon as I felt the bolt-on ride. Great! That was back in the '90s. My body mounts look brand new, but solid mounts have been on the 'list'. Where's my credit card?

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post #13 of 26 (permalink) Old Jun 21st, 08, 04:29 PM
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Re: Solid or Poly Body Mounts?

Quote:
Originally Posted by Fred Ficarra View Post
Now you guys have done it! I welded up my sub frame connectors as soon as I felt the bolt-on ride. Great! That was back in the '90s. My body mounts look brand new, but solid mounts have been on the 'list'. Where's my credit card?
How are you going to get them in with welded SFC's?
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post #14 of 26 (permalink) Old Jun 21st, 08, 06:57 PM
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Re: Solid or Poly Body Mounts?

Quote:
Originally Posted by dipren443 View Post
By putting SFC's in, you are fixing the front subframe to the unibody. If you use poly or rubber, you allow the subframe to flex. Solids will form a rigid connection. With the flex, you are putting added stress on either the SFC's bolts or welds if welded in. You may end up with stress cracks in the welds or fatiguing the bolts.
Just something to think about... Hotchkis sells a weld/bolt in subframe connector that comes with a urethane body bushing as part of the kit. They know a lot of guys weld instead of bolt the connection at the subframe. You have to weld them at the rear and I'm sure if there was any chance for the connectors to cause lateral damage because of the bushing material they would not include urethane...

Many subframe connectors I have seen get welded to the subframe not the floor pan, it doesn't seem to me there would be an issue no matter what material bushing you use. I have seen some that you cut the floor and weld them where the connectors run through the floor. In a case like that maybe the solid bushings would avoid stress issues.

It's been my experience that over all solid bushings anywhere on a street driven car that isn't destined to see some track time is over kill. Don't take that as I'm telling anyone not to use them. I know a lot of guys have near full race cars in their garages that they use on the street. Most of these guys are more hardcore and would not be asking "Should I use? questions...

Also keep in mind solid bushings typically lower the body on the subframe which can impact every piece of body panel bolted to the front clip. Not a problem when the car's apart but replacing body bushings once a car has been on the road could lead to a lot of work...

...Dennis

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post #15 of 26 (permalink) Old Jun 21st, 08, 07:40 PM
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Re: Solid or Poly Body Mounts?

It really depnds on what your doing with the rest of the car. Nothing tightens the body / frame like frame connectors and solid bushings. But if your doing stock suspension and 15" polyester repro tires, you might as well do rubber bushings. If you going Pro touring with some type of suspension package, low profile wider tires, you will get a lot more out of the car with solid bushing and frame connectors.

Hardtops absolutly benefit from connectors and solid bushings, but if your car is a convertible you will be simply stunned at the improvement with solid bushings and connectors! Almost completely eliminates the cowl shake.

How much horsepower really does not matter when your talking about the overall handling and feel of the car. But know in advance that feel is firmer, harsher (is that a word) and absolutly more aggresive.

Also, if you going to be dead hooking on slicks side stepping the clutch at 4000 RPMs, all the above applies also.

If you looking for solid bushings, we stock the Speedtechs. Nice kit WITH bolts / washers for $110.

We don't use many rubber bushings in our shop, but we don't use many polyester tires either.
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