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Bob, what you say may very well be true. I have been advised by a major Mopar restorer that he would only use poly if he was making a bracket racer.
My senses are probably not that sophisticated to notice any difference, but given a choice between OEM especially NOS and anything else, I'll got for stock every time. It's a matter of personal preference and I would never try to convince anyone that its the only way. Also, my right front mount is one of those engine mounts modified with a bolt, and it does act like there is little or no isolation at all. It is now, after all, metal to metal contact and no longer isolated. It vibrates at idle and it can be felt all over the car. I think (hope) thats what is causing it. I'll let you know when I get them changed! That problem will be much different I think that the poly issue. Is poly a real problem? I think certainly not. Best, MIke Moore On Feb 13, 2014, at 11:25 AM, Bob Jasinski <rpjasin@xxxxxxxxxxx> wrote: Mike et al,
I am familiar with the concerns about substituting polyurethane front end components in place of OEM rubber originals and have heard and read of others finding the ride objectionable after rebuilding a front end using aftermarket polyurethane parts. In fact, that is the reason I went with original OEM front end components in the A body Barracuda project I have in my garage.
Having written that, I am at a loss to see how that would translate to the same concerns regarding engine mounts. As an example, about 10 years ago, John Hertog wrote a piece for our 300 website tech section, (I think it is still there) about repairing a failed engine mount, by making a "Franken mount", that is, drilling through the broken rubber mount and securing it with a bolt, through the steel into the failed rubber, and back out again thereby allowing the original mount to be placed back into service.
I emailed him with questions about the fix, and asked whether there was any noticeable vibration from the engine transferred to the frame using the Franken mount, and he replied back that he could not notice any difference. Based on this feedback, my thinking was that since he did not notice any difference with his solid, bolted mount, that a poly mount substituted for a rubber OEM mount would have little to no affect.
Anyone on the list have the poly mounts from Imperial Services installed on their car? Did you notice any difference? Another question, if poly is a concern, does anyone know of a service that revulcanates OEM mounts with rubber? As a consultant for the Inc. Club I get calls from individuals dealing with failed motor mounts, and have been referring them to Imp Services. Recently, a high school friend of my daughter asked me for help finding mounts for the '63 Imperial he inherited from his grandparents, and I sold him my spare mount set to help him out as the repops are pricey.
Bob J
From: Michael Moore [mailto:mmoore8425@xxxxxxx] Bob, I have restored several British sports cars. Polyurethane bushings in all sorts of colors are sold by major parts suppliers, and people love them because "they're stiff" and " they're tough". There is nothing wrong with them. I just prefer not to use them for a subtle reason.
1. Several years ago, Sports and Classic Car Magazine (I think) had a cover story abut a comparison between two MGA's, both of which were on the cover. The cars were identical even to the light blue color. One car was totally original and very low mileage, around 30,000 miles as I recall. The other car was freshly restored using modern materials and parts but still authentic. Two writers left in the two cars for a weekend.They drove a day to the other part of the country, overnighted, then swapped cars the next day for the trip back home. They then compared the cars and wrote about it. They were unanimous that the original car was superior in every way, especially handing and ride. The fresh restoration was very stiff and harsh riding, and not as comfortable for a long trip. It was attributed to several things but one major one was polyurethane bushings and body isolators throughout.
I also had a friend who worked at a British sports car factory and he once mentioned how much trouble the engineering department went to determine exactly what hardness rubber to use in various bushings, They would take it to the test track, record data, then spend time removing softer bushings to install higher hardness bushings or vice versa. A lot of engineering time was spent to get everything as it should be.
Likewise, I personally designed some very large industrial isolators many years ago. I started with something like 85 Shore B hardness, tested, and went to 80 and tested. I eventually selected the exact hardness needed for my application. I have never seen any hardness specification on any isolators and would not expect anyone to ask or answer-like I said, its subtle!
Finally, I restored a 63 E Type a number of years ago. It used OEM or NOS parts wherever possible and no polyurethane in any of the bushings or isolators. It drove like a dream. Then, my son asked me to restore one for him, which I did-but he wanted all the boy racer stuff. Competition shocks, nice red poly bushings , etc. So for a year, I could drive either car as I finished up his car. I would not have realized how horrible his car was had I not been able to drive my car also. It was a different car-but it was very stiff, and he loves it!
That's my opinion, and there is nothing wrong with poly bushings. They are tough.
Best, Mike Moore
On Feb 12, 2014, at 5:07 PM, Bob Jasinski <rpjasin@xxxxxxxxxxx> wrote:
Michael, That's bad news. I just let a spare pair of originals go because I thought I could always get new ones. I wonder how wide spread the problem is, polyurethane is very popular for front end parts. Any others on the list having a bad experience with the repro's? What does Imperial Services have to say? Warranty? Bob J From: Michael Moore [mailto:mmoore8425@xxxxxxx] Bob, Thanks I prefer not to use polyurethane, I have a used floating power poly mount now which is separating, I'd like to find an NOS rubber mount, or a good used one if possible. Thanks, MIke Moore On Feb 12, 2014, at 4:21 PM, Bob Jasinski <rpjasin@xxxxxxxxxxx> wrote: Michael, Have you tried this vendor? http://imperialservices.net/imps.html Bob J From: Chrysler300@xxxxxxxxxxxxxxx [mailto:Chrysler300@xxxxxxxxxxxxxxx] On Behalf Of Michael Moore Hi Tom, Jeff responded to my email today and has been terrific help. I need a NOS 220237 left side engine mount though and he doesn't have them. Mike Moore On Feb 12, 2014, at 4:59 AM, Tom Cox <tdcox@xxxxxxxxxxxxx> wrote: Jeff Carter has more parts than you can imagine. Contact him at JC Auto Restoration in Seattle. Google for website and phone number. Great guy; good to work with. He restores our letter cars to perfection but has warehouses full of parts. From: Chrysler300@xxxxxxxxxxxxxxx [mailto:Chrysler300@xxxxxxxxxxxxxxx] On Behalf Of Gern Blanstin Hello there, I'm new to the group and the 300 club. I have two 300k's as well as a 300G that I'm trying to bring up to par. Currently I'm trying to hunt down a pair of inner fender inspection plates for the 300G. Any info on their potential acquisition would be appreciated. Thanks
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