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Help with 2nd gen ('67) body mounts?


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With the exhaust out, it just opens up a whole world of things to do before putting the pipes back in the way.  One of those things is the rear body mounts.  I really don't expect anything else for Christmas this year since I got all six bolts out of the mounts in the back end of the car without breaking any retainers, and the bolts look reusable too!


I ordered a complete kit from, I believe, classicbuicks.com.  I jacked one side of the body off the frame just enough to get the three mounts out.  


The picture below shows the mounts for one side of the car.  I put two of the lower ones in the two rear most locations and the middle one over the rear axle.  When I dropped the body back down there was about a 3/16" gap on the one over the axle.


So, my question is: can someone tell me where the mounts go?  I assumed the top two go under the firewall (two on each side).  I also assumed that the middle one went under the radiator, but after holding it next to the one that's in there, it's obvious that it's too thin.


The second picture shows the ones I took out.  The one on the bottom os the one that went over the axle.




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The new mounts for the rear are definitely too high. Looks like there is a seam at the point that would be about the correct height. That lower piece doesn't separate does it?

I spent many hours researching body mounts. When I did mine I asked classic Buicks for the dimensions of the mounts in their kit and they refused to give them and said "don't worry they will work". That didn't make me feel warm and fuzzy. Its great they make mounts with the large washer and internal sleeve but unfortunately not all correct dimensions for our cars. The large diameter one is not the same either as its smaller OD but suppose it would work OK height wise. Smaller diameter means less load carrying capacity in an already overloaded position (firewall). No one makes that one exactly.

If you look at your firewall mounts they will probably be collapsed pretty good despite there being 2 on each side. There's a lot of weight on these since the closest mount is over the axle due to the X-frame. I bought $2 hockey pucks and machined the 4 large diameter top cushion mounts for the firewall and 2 above axle so they are correct height and diameter. I believe the bottom cushions are the same in every location.

I believe CARS has correct mounts for the rear but you may need to salvage your internal sleeves. My 4 rear originals were in great shape so I re-used them. Take dimensions from yours and call CARS. You'll have to guessitmate the amount the height is squashed (maybe 1/8") and then also subtract a small amount for the OD since when they squash the OD grows.


Pay attention to the rad support mount if you change those as they are installed with a steel shim about 1/4" to keep front fender aligned

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I did a thread some months back re `64 body mounts and what was available in the aftermarket, from Cars, etc...if you do a search for it you may find it informative even though it is geared to a `64 model.

If my memory serves me correctly in your picture the top mounts go under the core support, the middle mount goes at the rear and the lower mounts go in all other locations.

I have a few NOS body mounts and new mounts which GM superseded for the originals. If I have time I will take a pic of the NOS mounts and you will be VERY surprised at what time and gravity/weight does to change the appearance of the mounts!

As Jason has commented you may or may not find shims at the core support location. This is an adjustment point to align the front clip with the body once attached to the frame so whether there are shims or not and how many shims are present will vary according to the adjustments which were necessary to achieve alignment. Buick used shims of varying thickness for this purpose. I have worked on many cars on which the shims varied in thickness from one side to the other. The shimming arrangement is not necessarily symmetrical and varies according to the demands of alignment and factory dimensional tolerances which can vary from one car to another.

  Tom Mooney

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I just remembered I recorded dimensions and part numbers of all my original mounts. The 4 top mounts behind the axle appeared have little to no collapse based on an almost straight sidewall with no bulge. They were 2-1/8 OD x 3/4" high with a large washer vulcanized to the rubber. This large washer is recessed so the top is flush.  The part number is 1376795 which was also same for the rad support mounts.


For the firewall and over axle mounts the dimensions (adjusted for collapse as close as possible) is 2-7/8" OD x 3/4" min to 7/8" max high. My car had two different part numbers for these mounts 1376803 and 1376798. Visually the only difference I could see was one had the sets of 3 vertical ribs on the OD and one was smooth. Good chance there was another difference though like maybe durometer of the rubber for example.


The steel internal sleeves for all mounts were the same dimension 7/8" OD x 11/16" ID x 1-3/16" overall length. This helps indicate all top mounts would have been the same thickness. I believe the internal sleeve would contact the steel washer on top mount and on bottom mount therefore acting as a "squeeze" limiter when the mount bolts were tightened.


The lower mounts had part numbers of 1376804 and 1376797. One had vulcanized washers and one had a washer not vulcanized.


Though it may be irrelevant the thickness of the large steel flat washers vulcanized to the mounts is 1/8"

Edited by JZRIV (see edit history)
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Thanks for all that info.  Here's what they gave me:


(6) 1369650 (small diameter)

(2) 1376803 (medium)

(4) 1383298 (large)


I did a quick search on the 1383298 number.  It looks like it's A-body.  I'm thinking that this kit is just an assembly of A and B-body mounts.


Apparently the assembly manual has the part numbers in it.  Anyone have an assembly manual?

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  • 3 weeks later...

After spending entirely too much time on the internet trying to learn about 2nd gen Riviera body mounts, I decided that I didn't want to chance buying additional mounts - especially after already investing in a "complete" set.  So, I used a large tubing cutter to make a line on the circumference of the mount and had at it with a new, fine-tooth hack saw blade.  It cut better than I thought it would and came out reasonably well.  I also trimmed the metal bushing, which is not steel on these mounts.


I got one side done, and I'm confident that I'll get the six mounts on the rear of the car changed out, before the new exhaust goes in.  I'm not sure what I'll do in the front, since the remaining mounts are obviously way off from what the front mounts and radiator support look like.


Another plus - my original bolts cleaned up nice with just a minute on the wire wheel.






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  • 1 year later...

Hi , I just fitted the exact same set of bushings on my 66 riviera - unfortunatly before I came across your post.

I installed the 2 lower ones in for the radiator support , the 4 middle ones under the cowl and the 6 remaining in the rear. Obviously the new bushings are higher then the old ones but I suppose I can live with that. Lowering the car down to the frame they all touched the same time without any shims required. So far so good. My problem is to get the correct gap between fenders and doors due to the low bushings I used in the front , I made spacers to put on top of the radiator bushings 1 1/4"  (30mm) high in order to align the fender/ door gap. I know there was factory made spacers of appr.1/2" on the old ones but still I think this is a bit strange.The driver door has an even gap of 3/16" in the aft to the quarter panel but of some reason I am not able to get an even gap under door to rocker ( about 3/16" aft and almost 1/3" in the front) Maybe it is acceptable or not I dont know? Passenger doors fits perfect.

Did you have to put any shims / spacers into your radiator mounts to line up your fenders?

Please have me excused for any wrong spelling (Norwegian) :-)

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Riviera 66 - Welcome to the forum. Your spelling/English is better than some people that were born here!


Gaps were not perfect on these cars when new however the bottom of the door to rocker should be pretty close otherwise there will be obvious mismatch between the lower stainless trim pieces but again we have seen many examples of factory cars where there was mismatch while others are nearly perfect. Most people realigning want to get it as close as they can regardless of what the factory did.


Door alignment on these cars is an acquired skill taking many hours if you've never done it. Patience. Adjustment can me made between door and hinge and hinge to main cowl. When one change makes another worse, what you end up doing is splitting the difference or making the worst part least noticeable. Often it will appear there is no way to make it better but if you keep experimenting, sometimes you will be surprised at what the smallest adjustment in the right direction can make. Always scribe or mark your starting point around hinges so you can go back if you make it worse. I remove the striker post so it does not force the door up or down when going through aligning process.


I usually see 1/4"-5/16" (6-8mm) spacers (large heavy steel washers) on the radiator support bushings on 66 cars. These were to aid proper front clip alignment. If your whole body has been raised due to new incorrect height bushings, you may need to raise the radiator support by the same amount. this is why I refused to use the too high body cushions. Not sure what other problems that may cause.

The fenders are typically shimmed at the rear (door side) also.


Having said all that, I would go back and cut down your new mounts that are too high as RoadShark did. This avoids an unnecessary risk of causing other problems. But I tend to be more particular than others.


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                     I am puzzled why you are changing the mounts if you are not doing a frame-off restoration. The old mounts in the picture

are in fabulous shape and would have lasted another 50 years. It seems to me a can of worms best left unopened.

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They didn't look so fabulous in the installed condition, were holding rust in, and weren't holding the body off the frame at the original height.  If I didn't address the rust between the mounts and the body now, they'd be going through the floor soon.

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Thanks for all input :-)

I probably will redo the bushings as RoadShark did in order to not get any more issues later on. I was playing around with the door alignment for 3 days and it looks quite good except for the gap to the rocker , also the stainless trim on the driver door was lower than the passenger door. I do not know if that is from factory or if it has been adjusted as the car was repainted some 20 years ago.

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