bonding rubber -- age issues

[RandalPark@xxxxxxx]

For some reason the rubber bonding issues that you speak about seemingly 
effected '63, '64, & '65 Imperials more than the previous three years. Every 
'63 that I have gotten to know very well has had at least one broken motor 
mount, a broken transmission mount, and broken carrier bearing insulator. This 
is much the same with '65 cars, but seldom have I seen this in other years, in 
fact I have looked at over 100 '60 Imperials and only come across a broken 
motor mount twice. 1962 models seemed to beak the transmission mount, but the 
motor mounts seem to hold up as well as 1960-61.

As you suggest, mileage isn't necessarily a factor. It has more to do with age. 
For this reason, I never by "new old stock" pieces when looking for any of 
these parts. I have had carrier bearings re-manufactured, and I have ONLY 
bought modern replacement motor mounts and transmission mounts. 

When I originally bought my 1965 Crown back in '74 I noticed that it had these 
problems, and paid the local Chrysler Dealer to correct them. A short five 
years later, the same parts needed replacement again. Oil from leaky valve 
cover gaskets and heat from the exhaust manifolds don't help, so it is 
important at least that the heat shields be kept in place.

There is a great mount supplier that I found out about here on the IML last 
summer over the Web. If I remember to I will check my catalogs and post the 
name. I don't think that they have made the carrier bearing mount yet.

Paul

 In a message dated 4/2/2004 3:52:38 AM Eastern Standard Time, 
cbody67tx@xxxxxxxxxxxxx writes:

> One thing to keep in perspective, is that as rubber ages (whether on a 
>vehicle or in a box), it's loosing its internal oils and will basically dry 
>out.  When it starts cracking, there's no stopping it.  PLUS, many of those 
>parts have been laying around for a while so even though they have never been 
>installed, the deterioration has started.  Similarly, the NOS rubber parts are 
>even older still.
>  
> A while back, in one of the Buick discussion groups, several participants 
>were having trouble keeping motor mounts in their cars.  They were getting 
>either replacement mounts or NOS mounts.  They all broke before too long (as 
>they were not the later version of "fail safe" mount).  Key thing was the age 
>issue I mentioned above.
>  
> If drive shaft "whip" is an issue, there might well be some other issues that 
>need to be addressed in the drive line.  GM has used three-section driveshafts 
>in some of their motorhome chassis with no real problems (similar torque, more 
>weight, etc.).  More vibration issues than "whip" issues, typically.
>  
> Each of the driveshaft joints need to be in a particular angular relationship 
>to the other part of the driveshaft.  Adjusting the carrier bearing assembly 
>up or down with shims takes care of that, if it's been disturbed from the 
>factory setting for whatever reason.  I kind of suspect that a sagged rear 
>spring set might be more critical than the carrier bearing height needing to 
>be adjusted to get rid of driveline vibrations on heavy acceleration, for 
>example or heavy loads.  The service manuals cover all of those issues.
>  
> What CAN kill a carrier bearing is water intrusion into the sealed bearing.  
>Typically, there should be metal water shields on the front and rear of the 
>bearing.  The metal shields might have disappeared during the life of the car 
>"as they are not needed with a sealed bearing"--allegedly.  BUT it was our 
>experience on my Dad's '69 Chevy pickup that they are necessary and a sealed 
>bearing isn't really sealed, or at least as some might suspect.  Each year, 
>after a dealership tech changed the ujoint and chunked the shields in the 
>process, we had to replace the bearing.  Then one of the shields got bent and 
>rubbed a hole in the rubber insulator of the bearing.  They got chunked again 
>and it was a new bearing each year.  Finally, we got some more shields and 
>that was the end of that problem.  Each one of those failed bearings, when the 
>plastic "seal" was removed, looked like it was full of sand.  
>  
> On those GM bearings, the rubber was replaceable as such.  The bearing was a 
>slip snap fit into the rubber and it all slid into the mounting bracket and 
>then the whole assembly and the water shields were installed onto the 
>driveshaft.  Several different variations and shapes of the rubber over the 
>years.  Perhaps one of them might be adapted so there would be 
> some recent manufacture rubber in the mix?
>  
> Just some thoughts,
> W Bell
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