Body Mount Drawings or Sample Part(s)

[CTX-SLPR]

Howdy,

 

Does anyone have a good set of drawings or an original dimension part (could be aftermarket as long as the critical dimensions are correct) for the main body mount bushings and even the elusive “oval” bushing?  After watching “Throttle Stop Garage” make custom C4 Corvette LCA bushing using a 3D printer and pourable materials I’d like to take a crack at doing new body mounts for mine in a slightly stiffer material.

 

Thanks

[NTX5467]

On the side of the existing OEM rubber body mounts is a casting number, which usually coincides with a GM part number.  The nuimber sequence will determine if that part is "Buick only" or if it was used on other GM vehicles.  For example, the body mounts on my '68 LeSabre are "Chevrolet numbers".  You might also put them into Google to see who might be selling them, too.

 

NTX5467

[60FlatTop]

When I mounted my '64 Riviera body back on the frame it was in 1993 and by that time all my mounts were crushed to at least 1/3 their original height. The two oval ones at the rear were the only good ones since they carry very little weight.

 

I went to our local Chevy dealership and we did a quick look for OEM parts but we knew the answer. They were obsolete. I asked if any were available for a, let's say, '76 Impala. The answer was yes. I bought six of them and they were fine. Of course in 1993 there were not a lot of people online to tell me how wrong I was. That's what holds the body up today

After working on GM cars all my life I find situations where the counter person can't reference my parts. I just make something up. If that didn't work I wouldn't still be doing it.

 

Cars designed by the men in gray flannel suits may not be the most creative but they sure are predictable.

[60FlatTop]

Here is one of my old ones. I have souvenirs all over the place.

 

The large diameter goes between the body and frame. The small one goes between the bolt head and frame.

The loss of height doesn't affect the length of the bolt so you can get the body shifting on the frame. Also the two rear ones above the axle and aft of the wheel well can squish down and make the car look like the springs are shot. The four under the cowl just make the hood and fenders hard to align.

 

Here is a new one at full height. Next time I get a chance I will check mine to see how the static weight has affected them over three decades.

 

[CTX-SLPR]

They sell the round mounts but not the oval mount.  Anyone have dimensions for the outside profile of the oval mount to try to make a mold for?

[RivNut]

When I changed out the mounts man my 64, I used the tone one in lieu of the oblong one. Not any real difference other than the shape as far as I’ve been able to tell

[CTX-SLPR]

I want to be clear, I am trying to reinvent the wheel here.  So while I know I can buy mostly accurate round ones and functional round replacements for the rear oval bushings, I want to try different durometers.  If I’m going to make molds, why not make an oval one?

 

Thanks

[60FlatTop]

Life is not always easy among those whom try to reinvent the wheel.

[CTX-SLPR]

2 hours ago, 60FlatTop said:

Life is not always easy among those whom try to reinvent the wheel.

If I wanted the easy (car) life I’d own a Camaro or a Chevelle or have kept that Skylark I sold because I wanted a Riviera again.

[NTX5467]

In your quest, you need to first find a durometer gauge.  They do exist and a friend who used to be in the left-hand turn dirt racing had one.  I borrowed it years ago to check durometer readings on various tires, in prep for trhe first Muscle Car Club Shootouts (sponsored by Comp Cams in the 1980s, and Muscle Car Review magazine).

 

I went to the new Super Shops nearby my shadetree shop and checked tires they had laying on the showroom floor.  Interestingly, the Mickey Thompson tires they had were just harder than their minimum hardness spec.  At 51 or 52 rather than the spec of 50.  At the time, that was the stickiest street tire around.  The other interesting fact was that I checked the tires on some C70 cab/chassis trucks we had on the lot and they checked "50".

 

So, look in the dirt track racer magazines and seek out a durometer gauge.  Then start checking tire treads, sway bar mount bushings, sway bar link grommets, and other body mount rubber items.  I suspect the most common-to-find "in the wild" will be for Chevrolets.  As the body mounts on muy '68 LeSabre have Chevrolet casting and part numbers, that would be a good place to start.

 

When I had the subframe mounts on my '77 Camaro replaced, I also upgraded to Grade 8 OEM bolts.  Body bolts can also deteriorate/rust in their hidden location, so the corrosion-resistant, MIL-spec coating helped there.

 

In body design, there are places designed to flex and tolerate flexing and vibration, as others are designed to not tolerate such.  Which can mean that as one part of the combination is strengthened, that just transfers those forces to places which were not designed to deal with them.  Certainly, a 10% additional flex-resistance might not hurt, but there is a limit which will reveal itself over time.

 

Enjoy the project!

NTX5467

[60FlatTop]

I have had the body off my '64 frame twice and also had a '68 X-frame Riviera off the frame. I saw them from the existing old bushings and the way the weight was distributed when I moved the bodies around.

To me it appeared the body is actually cradled between the cowl mounts and the mounts at the rear kick up over the axle. Those mounts were crushed the most in both instances. The four rear mounts around the perimeter of the trunk showed little crushing with the rearmost oval showing none.

 

With the body sitting on four jack stands I could easily lift the rear of the body by hand. The majority of the weight was concentrated at the cowl.

 

If I were building my car for a performance application and concerned about body movement against lateral forces I would want to increase the resistance to movement in the steel bushing area of the through bolts. I think that would affect the handling more.

 

I am the tech guy for the Buick Club of America on 1991-96 Buick Roadmasters. I have owned two and also a 1994 Impala SS which is the same basic car and shares much of the Caprice 9C1 police car build. Here is a good write up on GM body to frame mounting for those cars that gives pretty good insight into body mounting. Well worth the time to read.

 

https://www.impalassforum.com/threads/body-bushings-and-mounts.807785/

[CTX-SLPR]

Thanks for the reference, I’ll check it out.

[CTX-SLPR]

Went trolling through vendors to order a mount from to copy geometry and found Rubber The Right Way had dimensions on their site.  Can someone check the stock metal sleeves to get an OD to size the bore to more exactly?