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Re: motor mounts replacement Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Mon, 13 Jan 2003 15:48:23
In Reply to: motor mounts replacement, peter   [Profile/Gallery]
, Mon, 13 Jan 2003 15:20:01
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First, some terminology-
The upper engine mount - the 'dogbone' between the top of the engine and the chassis, is a torsion mount. On the right side of car there are two lower engine mounts. There is also a single mount under the transmission.
The rubber bushings in the torsion mount do develop small cracks over time. No big deal. However, if they develop large cracks, that's an indication of lots of engine movement and the bushings and mounts need replacement.
The lower mounts are hydraulic - a rubber bladder filled with fluid. If you see cracks, that's a bad sign. Major cracking says the mount has failed.
OK, when do you replace them? Well, if the lower mounts have failed, they'll stress the upper mount, and that bushing life will be greatly reduced. If the upper torsion mount fails, it'll allow a lot more engine movement, which will kill the lower mounts quickly. I would replace the lower mounts as a pair, mostly because the labor to do two isn't much more than to do one. If the lowers are shot but the upper looks OK, then just do the lower. You can always do the upper later. If the upper is shot, but the lowers look fine, I'd do them all, because chances are the lowers really are shot. That upper just didn't fail by itself - it was overstressed, and that means the lowers have been flopping around.
Different kinds - the lowers come as hydraulic (stock) and solid rubber. I believe you can also get urethane lowers, also. Hydraulic is the most compliant, then solid rubber, then urethane. Stiffer mounts will last longer, but in general, they will transmit more vibration. Upper mounts come as either the stock rubber bushing, or urethane, which is stiffer.
My opinion is that unless you've modified the car for more horsepower, stiffer suspension, etc, stay with the stock mounts. The stiffer mounts will transmit more vibration. How much? That depends on the individual engine. Some engines are very smooth, and stiffer mounts feel just the same. Some engines aren't as smooth, and you'll end up with a paint shaker for a steering wheel. Since this is a job you don't want to do twice, I'd err on the side of softer. Now, if you've already modified the suspension to improve handling, you've demonstrated that you're willing to trade some comfort for performance, so you're probably up for the risk of stiffer bushings/mounts. But if stock is fine for you, stay with stock.
You can get hydraulic mounts from a bunch of mail-order places, including Sobstory. Much cheaper than the dealer.
I'm surprised at $800. My local Indy charges about $400 for the lower mounts, and they don't discount the parts. I think the last time I did the lowers, I paid about $80 each for the lower mounts, and did the job myself. The uppers are pretty easy, and the bushings are about $20 each mail order.
posted by 192.249....
, Mon, 13 Jan 2003 15:20:01, Mon, 13 Jan 2003 15:48:23 <-- Viewing This Message, Mon, 13 Jan 2003 15:53:33
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