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Model, Year, and Engine

Ultra-Flex Rubber vs. Classic Polyurethane
Which is Better?
Some swear by rubber motor mounts. Others prefer the feel of polyurethane.

We say, "It's a personal decision."

Here are a few considerations.....

  • Daily driver or trailer queen or daily driver and weekend adventurer?
  • Sporty feel or cushion comfort?
  • Engine finely tuned or tuned in a fog?
  • Driveline survived a few drops or pristene?
  • Hot and dry or cold and wet?
Compare.

Characteristic
Ultra-Flex
Rubber
Classic
Polyurethane

Durometer (Shore A Scale)
70A
89A

Vibration Dampening
Excellent
Fair

Oxidation Resistance
Good
Excellent

Petrochemical Resistance*
Fair
Excellent

Temperature Rating**
-60 to 185 (F)
-30 to 185 (F)

Heat Aging Resistance
Fair
Very Good

Tensile Strength
Very Good
Excellent

Weather Resistance
Fair
Excellent

* Based on amount of bushing exposed in motor mount when installed on vehicle.
** Nominal performance retained within this range. Does not indicate failure outside this range.  
   
 
What's the dog say? Around here, the Brown Dog's word is law. And since we're in the heat of the desert southwest, we run Classic Polyurethane motor mounts. (Our 2.5L Wrangler YJ is our daily-driver and our weekend trail rig.) The Brown Dog likes the more secure feeling of knowing what's going on under the hood.
 
Designed to minimize vibration transfer. Whether you select Ultra-Flex rubber or Classic polyurethane, we strongly urge following all installation tips to take full advantage of the vibration reduction inherent in our design.

Particularly important installation tips include:

- Do NOT over-tighten through-bolts. Even slightly over-tightening these bolts defeats the vibration transfer reduction designed into Brown Dog mounts.

- Inspecting and/or changing transmission mount when changing motor mounts. It's practically impossible to inspect a transmission mount until the cross member/transfer case skid is dropped and the transmission mount nuts removed. Since we recommend loosening the transfer mount bolts prior to raising the engine (using a block of wood and jack under the oil pan), most customers change the transmission mount when they change motor mounts.

- If you have any questions, not sure how to approach something, not sure if it looks right, or not sure if a vibration is 'normal,' call us. Our phone is forwarded 24/7 for technical assistance.
 
Still unsure?
Give us a call, 866-401-3877 or email
info@browndogindustries.com