65 Riv, body mount comparison/opinion

I would appreciate your advise/opinions/experience with a minor detail I am dwelling on.

I bought a full body mount kit for my 65 Riv from Marc Smiley at Classicbuicks.com many months ago. Very cool upgraded looking kit, very easy to order & no problems with the fitment onto the frame holes. I pulled the trigger for the purchase after reading that classicbuicks.com is one of the only places to get a full kit & lots of members here were happy with the kit.

The kit includes 10 of the taller bushings (first one in pic), 2 of the lower profile bushings (third one from left, to replace the oval ones at very rear per Marc) & 12 lower bushings (also known as insulators) packaged from Steele Rubber which have the metal washer molded into the rubber.

As you can see the first bushing is almost twice as tall as the original bushings. I understand that the weight of a heavy Rivi body plus 50 years can compress a lump of coal into a diamond. But I feel I will get somewhat of a body lift like the 4x4 guys do on their trucks if I use the taller bushings. I spoke to Marc, super easy to talk to with great customer service. I asked if I could exchange the 10 taller bushings for the lower profile bushings instead & he didn't hesitate to say "no problem."

Before I send them back for exchange, I wanted to ask if any of you experienced what I described as a body lift with these taller bushings? Do any of you foresee having problems with the shorter bushings?

thanks in advance

Some help please...

Should I use the taller bushings??

Or should I go with my gut & get the shorter bushing all the way around??

Has anyone purchased this kit??

Anyone??

Come on...64 views & not one comment??

David,

CARS, Inc. also offers a kit (BMK635 $149.00). It does not use the taller bushings rather a shorter bushing. I looked into the "technical basis" for the bushings we use and could not find a solid correlation. I could not find a listing in the parts books indicating the original part numbers for the 65 Riv. We have been selling several bushings for that vintage for many, many years without issue. So my weak conclusion is that the taller bushing is incorrect.

If you can get part numbers I can research this. We make a bunch of mount/cushions. If by chance you can't get satisfaction elsewhere, feel free to contact me directly.

Some help please...

Should I use the taller bushings??

Or should I go with my gut & get the shorter bushing all the way around??

Has anyone purchased this kit??

Anyone??

Come on...64 views & not one comment??

I would not use the taller bushing without specific details on how much it will compress. With experience and hours of research I did trying to determine original correct diameter and thickness on my 66 mounts, while there is some collapse/compression of the bushing with weight and age, I don't think it would be that much. Taller bushing pictured is too high IMO. Not sure how applicable my experience with the 66 bushings are comparable to the 65 but suspect there are similarities.

The two pair of new front most bushings are probably smaller diameter than what was there originally. The large diameter bushing in the correct height is not available and I was not comfortable using smaller diameter ones because it is evident from the amount of compression/squash even with two bushings side by side the originals were overloaded and a bit undersized for the weight. Big car and the next closest bushings are above rear axle!

One thought is perhaps the taller but smaller diameter bushings will compress more since they are smaller diameter and can't support the weight as well as a bushing with more square inches of surface area. You wouldn't know that until you had full weight on them and by then its a hassle to swap them. That's why it would be nice to hear from and/or get pictures from someone who has used them.

I ended up making bushings the correct diameter and thickness out of hockey pucks. The drawback is I could not use the internal steel sleeves which originally limited the amount of compression when the mount bolt was tightened but felt the sacrifice was worth it.

Hockey pucks? What a great idea! Make your own to whatever dimensions you want.

While we're on the subject, what is the purpose of a "rubberized" body mount anyway? What is it isolating from what? The engine / trans sit on their own mounts so it's not to isolate vibrations from them. Most of the suspension rides on bushings. The new unibody cars don't seem to have body mounts. So, what's the need for them? Why couldn't you use something solid?

Ed

I am not an engineer or anything, but i would think the risk you run with using a solid over rubber is possibility of breakage and noise. The noise would be like when we went from rubber front end bushings to polyurethane for instance. A lot of 70s camaro and firebird owners went to the aftermarket poly kits. If you know what i'm talking about then you know there was a specific noise they made. I think some of this was reduced by using graphite if memory serves correctly. They were a bit stiffer, but noisier. As to why you wouldn't use, say, a hockey puck in place of a rubber bushing - well, for those specific instances when you throw a ton of force in one area i would think it could just break in half. Maybe if you curbed it or something similar...a force spike of some sort. The rubber would turn the spike into a curve where the solid would not lessen it much. Rubber adds to the cushy feel with the trade-off being instant response, like with taller tires versus low profile tires.

Hockey pucks? What a great idea! Make your own to whatever dimensions you want.

While we're on the subject, what is the purpose of a "rubberized" body mount anyway? What is it isolating from what? The engine / trans sit on their own mounts so it's not to isolate vibrations from them. Most of the suspension rides on bushings. The new unibody cars don't seem to have body mounts. So, what's the need for them? Why couldn't you use something solid?

Ed

Ed it may be a little bit of a chicken and an egg question. In a unibody car (like today, although there were unibody cars way back in time too), because everything is fastened by a weld, body mount cushions are not necessary to isolate the body from anything. As you know there are body mount cushions on engine cradle attachments on unibody cars. Isolation in other vehicle systems is achieved by the use of other cushions and bushings. This manufacturing process is quite different than frame construction cars.

Cars for many of their years of production had bodies mounted to full frames, and since the body was attached to the frame by a threaded mechanical fastener - a cushion was necessary. This was basically a necessity of the production process. The cushions for the engine cradle or the full frame helped isolate any metal on metal vibration from the body and to a certain extent kept a tension on the threaded joint. I remember, from my time working as a Manufacturing Engineer in a few GM assembly plants, there were different durometer cushions used, and the durometer used depended on the location of the fastener on the car, and also there was a difference between the various car lines and models. In other words all the body mount cushions may not the same on one car or between different cars based on option content or model.

Within the constraints of the technologies of the time the different durometer cushions allowed for some differentiation between the different car lines and models on ride sound, perceived tightness and reliability (and likely other parameters). Since rubber fails or deteriorates over time and environmental conditions, a reliability was built into the specification. This would make some of the car lines sound tighter, have less rattles and vibration, and have these characteristics for a longer period of time versus other car lines. That goes for many of the cushions, bumpers and bushings used in other vehicle systems too.

The technology of today's materials, production processes, and engineering allow for the cars of today to be better manufactured with tighter tolerances, lighter and stronger materials, more reliability, and therefor they go further, last longer, and require less frequent maintenance (I am not casting any aspersions on all those well maintained vintage cars out there). This has driven much different manufacturing processes and methods used today.

So to a certain extent the way the cars were engineered (Frame or not to Frame) and manufactured drove the need for Body Mount Cushions, ergo the chicken and egg analogy. Sorry for over answering your questions Ed.

Rock On

gord

I have the classicbuick mounts on my '65. Even with compression they will be slightly taller than the original mounts (see picture). Tough to see in the picture, but the front mount is taller by about 3/16". I could not get pictures in the other locations, but most are around 1/8" to 3/16" taller; except for the rear most mount which was the same as the original. Now, I don't know if the comparison is truly valid as the original mounts may have been taller when they were new. I cannot tell you how the taller mounts impacted fitment of any other body parts as the car is still in pieces.

I would also add, when I installed the mounts I started in the front (actually under the firewall as the front end was not installed) and worked my way back. When I got to the rear there was a gap when I installed the mount, which disappeared as I tightened the mount. This made me uncomfortable as I am not sure how this will impact panel alignment later or whether I will need to shim the rear mounts to make things fit.

If I was in your shoes and did not yet install my mounts, I would try to find something closer to original. Last thing you are going to want is find things don't fit right when your are almost done with your project

Doug

Dave and I have been touching base on this issue. I have been checking original part numbers, checking original mounts and comparing to what is available in the aftermarket. I have accumulated quite a bit of info so to convey same may take several posts, but at this point, the info accumulated may not be able to provide "closure" to those doing a complete frame off...the research continues.

Regarding the original part numbers there are quite a few mounts listed with differing part numbers in each individual year. The different part numbers seem to relate more to diameter than height. An inspection of the original mounts indicates they are all the same height or at least very close.

So no matter which mount is used, the original style short mount or the taller replacement, in my opinion, it is important to use mounts which are the same height or very close. I would be concerned, if using drastically different heights, that some flex would be introduced into the body with negative consequences. This does not necessarily apply to the front most core support mount because these positions were intended to be shimmed at the factory to align the front clip with the rest of the body so varying height can be compensated for with shims at this location. I have inspected quite a few very original cars at the core support positions and found drastically varying shim heights and even some cars which are shimmed radically different from left to right! The original frames were not perfectly square especially as the frame progressed out to the frame horns.

Before I ramble on I should touch on terminology. The upper portion of the mount is called just that, the mount. But the lower part is called the insulator. I will be using this terminology to attempt to avoid confusion as I am a pro at precipitating same.

The original style (also dimension) insulators are available in reproduction from Steele. I found this

reproduction by searching the original GM part number. See pics...

The first 2 pics are a comparison of the original insulator and the reproduction. I would attribute the difference in height to crushing from the original body bolt and washer as there is no metal core in the insulator as there is in the body mount. I suspect the original insulator was the same height as the repro when new. Besides, except for the body bolt length, the height of the insulator doesnt matter because it is not situated between the body and frame but comes up under the frame. Keep in mind the insulator is the lower part. Note their diameter is the same.

The 3rd pic shows that the repro insulator indexes perfectly around the metal core of the original mount. This may be of interest to those who may only want to replace the insulators and not the upper mounts. The original insulators are prone to splitting (an improved insulator later...) so this is an easy upgrade not requiring lifting the body and is commonly needed.

The 4th and 5th pic shows the original style insulator on the left and an improved version on the right. Note that a washer is now molded in. GM went to this improved insulator in `66 (maybe `67) but the one pictured is a repro. I like this improvement as I suspect this will discourage splitting of the insulator but the overall diameter is smaller which I dont like for a heavy body like the Riviera. Also, no need for a separate washer to accompany the body bolt when using this improved insulator. Note this insulator will not fit without slop over the metal sleeve of the original body mount...but it fits like a glove over the sleeve of the taller replacement pictured in Dave`s original post.

As I researched this issue it became more apparent as research progressed that not only was it important to use a mount of the original height but to also find a mating insulator which fits well to form a functional "unit". Should we compromise the original mount height to get a good fitting unit or should we use a mount which is true to the original height with a sloppy insulator? I found myself encountering this dilemma thruout my research as different style body mounts were discovered.

It is worth mentioning as the parts books progressed thru the years Buick substituted the improved insulator for the original insulator IN CONJUNCTION WITH the taller body mount pictured in Daves initial post.

More in another post later this week...

Tom Mooney

Thanks to all who responded. There is a whole lot of useful information shared in this thread. There are so many knowledgable people on this forum, gotta love it.

I appreciate the help, I have decided to go with the shorter reproduction bushings with the Steele Rubber insulators that have the washer molded in the rubber. Thanks again

I had to shim up the fronts to get the vertical fender to door gaps right. 3/16" sound about right, but there was no indication the bushing I removed were taller in the nose. Zero help I know.

I got a chuckle out of the thread because Studebaker, with which I am well acquainted, used pieces of sidewalls from old tires for their body mounts. Engineering found them to be perfect for the insulation and the rigidity that they were after.

To continue the available body mount thread, more pics and comments.....

First, sorry for the dark pics, I`m certainly not a photographer.

The first pic is a comparison between an original mount on the left and a currently available mount on the right. It should be noted that GM superseded the taller mount in their parts books for first generation applications (maybe for subsequent models also but I didnt check?) to be used in conjunction with the improved insulator mentioned in my previous post. The mount pictured (on the right) is NOS as I have had these since the `80`s but it is also available as a repro. This mount is the same mount which Dave pictured in his initial post and is the mount Classic Buick is supplying (except for the 2 rear most mounts which are shorter) along with the improved insulator. Note that the replacement mount, in addition to being taller, is not as wide as the original and the metal sleeve is a larger diameter (see pic #2). This mount drops nicely into the frame holes as the lower "collar" is the correct diameter BUT THIS MOUNT WILL NOT FIT IN THE CORE SUPPORT POSITION ON `63 AND `64 MODELS because the collar is too large. The size of the frame hole in the core support position was changed and made larger in `65. This is confirmed when researching part numbers. In `63,`64 Buick specs out a specific part number for the core support position but in `65 they spec out the same mount used in other positions...the bean counters were alive and well in `65! No need for `63, `64 owners to fret as there is a repro mount which will fit the core support position...more in a later thread as i dont have pics to illustrate same.

The third pic illustrates an original mount mated to an original style insulator on the left and the superseded mount and improved insulator (available from Classic Buick among other sources) on the right. Notice in both cases the fit between mount and insulator is tight but will assemble easlily. It is possible to force an original style insulator over the metal sleeve of the superseded mount but this definitely swells the insulator and may be a PITA to assemble. For those wanting an original appearance and diameter of the lower insulator this may be an option.

Also worth noting is compliance/softness/hardness/durometer (as referred to in Gordon`s post above) of the superseded mount. This mount is definitely on the soft side and will compress (but very little due to the metal sleeve) and flex when installed. This durometer relates to vibration transfer, body flex, etc and at this point becomes "engineers only" territory. Again, see Gordon`s excellent post above. These durometer specs are not available when researching options but suffice to say there will no doubt be performance differences between this superseded mount and a hockey puck. This is not to say one is "better" than the other, because ultimately the option chosen is the owners preference, but there is a ton of advertising copy from this period relating to body mount "tuning", especially from Oldsmobile, and IMO this is a worthwhile consideration.

In researching available body mounts I found the "G" body enthusiasts are into the details regarding mount durometer. Apparently, the GNX used a harder and greater number of mounts as compared to a standard Regal. The engineers eliminated a mount or two from some G body models because they WANTED some body flex. This may also be true when comparing G body models from the different divisions, ie, a Pontiac Gran Prix may use a harder mount than a Buick Regal. Apparently there is a color coding which relates to mount durometer. This seems correct as the NOS mount pictured above has several different part numbers molded into it and there are different colors associated with each part number. So, I`m assuming, same dimensional mount but a different color code provided for the assembly workers so as to choose the correct durometer depending on a particular build?

All for now, hope this thread proves useful for someone, more later,

Tom Mooney

Around 1994 I went up to the Chevy dealer in town and asked for "X" number of 1976 Chevy Caprice body mounts. I pointed and grunted at a picture in the parts book and he ordered them. The oval mounts at the rear were OK so I reused them. I'll be out in the garage this afternoon. If I get time I'll see how they are holding up after 20 years; nothing noticeable standing by it so I'll have to look under there.

If that sounds a little casual, remember in 1994 I would have had to write letters, lick stamps, and wait for replies or make "long distance" phone calls for this kind of information.

Learned something today; I always thought a durometer was the 10th's column on a Chrysler product odometer.

Bernie

Bernie

This post highlights the distinction between `63-`64 core support mounts and the `65 arrangement. The hole in the `63-`64 frame rails is smaller in diameter than the hole for `65. I suspect Buick made this change to utilize the same mount which appears at other frame locations in the core support position. The "correct" `63-`64 core support mount has a smallish collar as compared to the other positions. See pics.....

The first pic is the `63-`64 replacement mount which is marketed by Steele. When searching the original Buick part number for this mount the Steele bushing came up. I am assuming Steele used an NOS example to reproduce/market their mount but I cant confirm this. The mount looks smallish in diameter as compared to my `65 cars but in fairness I dont have an original `63-`64 mount to use as a comparison. Also, Buick speced out a different part number for the `65 bushings.

The second pic compares the Steele repro mount on the left to the GM tall superseded mount (see Dave`s and my posts above) on the right. As can be seen in the pics the collar, the part of the mount which fits into the hole in the frame rail, is much smaller in diameter on the Steele mount as compared to the superseded tall GM mount. This can be addressed by trimming off the collar on the GM mount, which may allow the mount to shift, or enlarging the hole in the frame. But for those seeking a drop in mount the superseded GM tall mount will not fit in the `63-`64 frame.

The third pic illustrates the fit of the appropriate insulators (lower mount) to their mounts. On the left is the Steele repro mount fitted to the original style insulator and on the right is the GM tall mount fitted to the "improved" insulator. It is possible to force the original style insulator over the projection of the metal core of the tall GM mount but the "improved" insulator is a sloppy fit when mated to the Steele repro mount.

The fourth pic illustrates the difference in diameter in the mounts where the bolt is inserted. The Steele repro mount is the correct 7/16ths diameter whereas the tall GM mount is considerably larger. Which circumstance is better is debatable. A nice fit between fastener and mount will discourage shifting whereas some clearance between the metal core of the mount and the fastener might prevent metal to metal contact and also allows some wiggle room during assembly. I dont think it a significant issue but if I had to exercise a preference I would choose a better fit.

Just a word about shimming at this location.....it is my opinion GM provided a short bushing at this location to allow a maximum range for shimming. Buick offered multiple shim thicknesses and I have inspected many cars with radically different shimming dimensions. This the position where Buick compensated for production tolerances in the mating of body and frame. I am therefore skeptical about using a tall bushing here as its installed height, without shims, may exceed the proper dimension to align the front sheetmetal with the body. The last pics are the Steele mount installed in a `64. There was no evidence of any frame or accident damage on this car and the sheetmetal is aligned properly. Notice it took quite a few shims to finalize alignment. This is OK, it was meant to be so.....................

Pleas note the original GM shims would be individually much thicker, cheers,

Tom Mooney

Great information Tom. I'm getting ready to put the front fenders/inner fenders back on myu '64. This is invaluable.

Thanks,

Ed

Great information Tom. I'm getting ready to put the front fenders/inner fenders back on myu '64. This is invaluable.

Thanks,

Ed

Thanks Ed. If you have the original mounts it would be great to see a pic to compare it to the Steele repro, or whatever other mount you decide to use. As I stated, I dont have an original `63-`64 mount to compare. Even a pic of an installed original `63-`64 mount would be helpful.

Tom

I'll take some pictures of what I pulled off and post them. The shop owner, where my car is, is in Iceland celebrating a wedding anniversary so I won't be able to get access to the mounts for at least another week.

Ed

On 10/29/2014 at 8:11 AM, CARS- Inc. said:

David,

CARS, Inc. also offers a kit (BMK635 $149.00). It does not use the taller bushings rather a shorter bushing. I looked into the "technical basis" for the bushings we use and could not find a solid correlation. I could not find a listing in the parts books indicating the original part numbers for the 65 Riv. We have been selling several bushings for that vintage for many, many years without issue. So my weak conclusion is that the taller bushing is incorrect.

If you can get part numbers I can research this. We make a bunch of mount/cushions. If by chance you can't get satisfaction elsewhere, feel free to contact me directly.

1190473 1965 Buick lasabre I’m looking for some bushing too