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Discussion Starter · #1 ·

What's the difference between SS and 9C1 upper body bushings? Harder rubber? wider? I would prefer a slightly stiffer bushing than the stock SS ones and am looking for confirmation.

Also, do the 9c1 or SS upper bushings still come with the metal spacer or do we need to order separately?

I have the frame off the car and plan on replacing upper/lower bushings and some of the rotted metal spacers. I did buy an Energy Suspension 4136 kit but in doing a lot of reading on this site most people don't recommend it. Fine, back it goes.

Now in reading a lot of threads on the bushings some people are actually recommending the 9c1 as being the better ride, firmer than the SS (which is what I want but not as hard as the ES)? Comments please.

I do plan on using the Mueller lower bushings and already replaced any of the body bolts that were worn out.

Following are the P/N for the pieces. I have both 9c1 and SS down. I need to order this asap so I can get the frame back on.

Thank You for any assistance. :D

Impala SS upper body mounts:
3524486 Upper Body Bushings (Pos 1,2,4,6)
10201228 Upper Body Bushings (Pos 3)
556755 Upper Body Bushings (Pos 5)
330992 Upper Body Bushings (Pos 7)

7B3/9C1 upper body mounts:
348080 Positions 1 & 3
330986 Position 2
330942 Positions 4, 6, & 7
488610 Position 5

Both 9C1/SS lower mounts (Mueller Mod):
457915 Position 1,2,3,4,6 (Pink) lower mounts
457917 position 7 (Dk Green) lower mounts

Both 9C1/SS lower mounts (GM OEM):

Bolts (note: Position 5 has no bolt):
Impala SS:
3524497 All positions except #3
3528567 Position # 3 (shorter bolt by 0.400)

3524497 all positions except 3
14085301 for #3 position only (shorter by 0.400)

Metal Spacer (reuse for aftermarket or you get with upper kits?):
6262234 for all positions

[ 06-28-2007, 12:54 PM: Message edited by: Gary Gevaert ]

Discussion Starter · #2 ·

SEO (9C1) upper mount/cushions are higher durometer or have fewer voids--they are the firmest/stiffest of any 91-96 B-body sedan upper mounts, to my knowledge.

Sleeves DO come with new GM upper mount/cushion assemblies.

I cannot speak from experience--you need to seek comment from 9C1 owners as to whether using the Mueller-recommended lower cushions is also effective with the 9C1 mounts, as I do not recall whether Mueller addressed this.

In looking at the SEO upper mounts I have and the way the 457915 lower cushions fit against them, I have some concerns about using these parts in combination. This may be a misplaced concern, since it is likely the upper mounts, once installed on the car and loaded with the weight of the body, will have adequate sleeve projection below the frame surface to effectively use the Muiller parts.

[ 06-24-2007, 11:13 PM: Message edited by: Navy Lifer ]

Discussion Starter · #3 ·
My personal experience is the SEO uppers and the Mueller lowers need a bit of a spacer to work together.
The Impala upper sleeve is noticeably longer than the SEO and when putting the combo together it appeared to me that the lower cushions were going to be "plowed" by the time the lower washer touched down to the sleeve.
I put a .120 spacer inside each lower to reduce squish.

Discussion Starter · #4 ·
Hi Bill,

That's what I wanted to hear. Thank You.

I needed the spacers as most of mine are rotted so that kills 2 birds with 1 stone.

The Mueller Mod Webpage indicates that his mod will work with 9C1's and older BBodies. What I think I will do is order the 9c1 uppers and use my current pink/green lower bushings to check the fit. If their ok then I will order new ones otherwise I'll go with the 9c1's. Come to think of it I may order a couple of the 9c1 lowers just to compare. I'll go hunt down the p/n in the morning for those - I believe there were more types then the SS.

Any comments on this from the 9C1 crowd?

Thanks Everyone

[ 06-25-2007, 05:29 PM: Message edited by: Gary Gevaert ]

Discussion Starter · #5 ·
Well, what do you know - the 9c1 lower bushings are all the same (and the same as the SS). pn 377801. I'll get one and check.

95wagon, I'm not quite following, could you elaborate please. Plowing means pushing outwards right? If the sleeve is longer then the metal spacer/sleeve should hit the lower washer sooner thereby keeping the bushing from being squished too much - No?. Adding a spacer would simply keep the squish even less. I'm not following something here.

Also, bill indicated that I get the spacer/sleeve with the 9c1 upper's - so does that not mean that I now have the shorter ones and should be ok? But that would mean more squish and possibly more plowing?

Now 95wagon got me thinking - I will have to go to the shop tomorrow and actually take a set of old upper and lower bushings (stock SS uppers and Mueller Mod lowers) to see how it fits together with the frame in the middle. (easy to do with frame out). I didn't really take a close look when I took it apart as I assumed that the upper bushing sits on the frame with the middle portion of the bushing that sticks out and the metal sleeve sticking through the whole; then the lower bushing sits against the frame as well but from the inside. The bolt through the middle then pulls the body down towards the frame and the washer on the lower towards the frame. This then allows the body to 'float' somewhat on the frame.
I always figured that the sleeve does not touch the lower washer and that torquing it down gets it close but still not touching. I guess that might happen when they get old though.

[ 06-25-2007, 12:51 AM: Message edited by: Gary Gevaert ]

Discussion Starter · #6 ·
Also, in reading these threads they mention that if you switch to 9c1 upper's that you need to get a shorter bolt for pos#3. Interestingly I have the stock uppers with a shorter #3 bolt already. There isn't an even shorter bolt is there? Too bad bolts don't come with pn on them :D

Also, it looks like a lot of people have done the 9c1 uppers and mueller lowers with no ill effects. I do want to understand what 95wagon is talking about - my way of learning about all the aspects of these cars.

Thanks for your continued help folks...

PS. Bill, you talked about spacers and washers in this thread:
Spacer-Washer thread

[ 06-25-2007, 01:14 AM: Message edited by: Gary Gevaert ]

Discussion Starter · #7 ·
The washer is supposed to touch down on the sleeve.
If it didn't the bolt could not be done up to a reasonable torque.

The Impala sleeve is longer so the washer touches down earlier.

Impala are the first two on left.
Wagon and SEO are on the right
When the Mueller recommended lowers are used with SEO uppers the lower get VERY squished by the time the washer touches down.
Also, it looks like a lot of people have done the 9c1 uppers and Mueller lowers with no ill effects.
Oh, there have been lots of things done here with no reported ill effects.
Have a look at all your pieces, think it through, and make an informed decision.

[ 06-25-2007, 01:35 AM: Message edited by: 95wagon ]

Discussion Starter · #8 ·
If it hasn't been stated clearly, I'll as few words as possible (for me, anyway).

What Gerry wants understood, I think, is that you can't apply proper torque to the body mount bolt if all you are doing is squeezing rubber.

The washer molded into the lower cushion is intended to contact the end of the sleeve that protrudes through the frame when the mounts are "loaded" by the weight of the body, and the bolt is used to secure the lower cushion into position, with a torque value of 52 lb/ft.

The thicker Mueller cushions appear to have been used in production with upper mounts that included a longer sleeve, since in most positions on an Impala SS, and especially with 9C1 replacement mount, with shorter sleeves, the rubber contacts before the washer, thus making proper torquing of the bolt impossible without some added effort with spacers, as Gerry has indicated.

Take a look at an FSM, Section 10-3, Body Dimensions, Frame, and Underbody. In several model year versions, you will find Figure 5 Body Mounts, which does a good job of illustrating what is happening with the mounts, cross-section views, etc.

The 1996 FSM I have also has an error, in that it shows that Body Mount #5 is bolted in place, which is not the case (this is illustration BT001103 date 5-13-95).

And yes, Gary, you are correct that all 94-96 (at least) B-sedans used the same lower cushion.

[ 06-25-2007, 03:45 PM: Message edited by: Navy Lifer ]

Discussion Starter · #9 ·
Thanx for the info guys - Duh, that should have made sense - you can't torque rubber.

I'm following now - Thank You.

I'm going to go away and do some thinking on this. My GM rep here also told me that his computer indicates that the 9c1's upper's don't come with the metal spacer (canada vs US?). I do know that you can get the impala ones still as a separate pn.

I have the 95 FSM at the shop - I'll Check it out.

Thanx again for your continued help - who would have thunk that body bushings could be this complicated! ;)

Discussion Starter · #11 ·
One more question:

Is the #3 body bolt for the 9c1 bushing setup shorter yet again than the SS #3 one (which is already shorter than the rest of the SS bolts)?

The information I collected is as follows and I'm just making sure I got it right because that would mean that the 9c1 #3 bolt is 0.4 x 2 shorter than the SS normal bolts.

Bolts (note: Position 5 has no bolt):
Impala SS:
3524497 All positions except #3
3528567 Position # 3 (shorter bolt by 0.400)

3524497 all positions except 3
14085301 for #3 position only (shorter by 0.400)


Discussion Starter · #12 ·
Gary and all,

I am still reading and digesting the above information. I don't mean to hijack this thread at all, I hope I am adding some useful information (though still a bit confusing to me...

I just ordered a complete body re-bushing "kit" from Dal.

Here is what I received:

Impala SS upper body mounts:
3524486 Upper Body Bushings Qty = 10
330992 Upper Body Bushings Qty = 2

7B3/9C1 upper body mounts:
348080 Positions Qty = 2

Both 9C1/SS lower mounts (Mueller Mod):
457915 Position (Pink) lower mounts Qty = 12
457917 position (Dk Green) lower mounts Qty= 2

(and 37-7888 47-2160 for radiator cradle supports.)

he said the caveat is that position 5 upper is no longer available. that is the reason on the above list I removed the position numbers. I think we need to modify 2 of the 3524486 to fit in upper #5.

Does anyone know what the "original" thickness was of #5?

I need to investigate, but since I recieved only 2 348080's do I use them in postion 1 or 3? 348080 is much firmer than the 3524486, but shorter, is this why the bolts for #3 are shorter (not said correctly, but obviously if everything fits closer, the bolt needs to be shorter so it doesn't bottom out)

I guess my above question is why on an SS are positions 1&2 same bushing with 3 different, and on a 9C1 1 & 3 the same with 2 being different? It seems to me that the relative closeness of 1 & 2 and somewhat 3, would require them to be about the same "height" (assuming the floorpan/frame interface is designed for the same "height"), or the bushings would become improperly loaded. If you have 3 springs on a table with 2 at 1" and one at 3/4" the taller 2 springs must compress to 3/4" before the load is shared by the 3rd spring.

Oh and all the new bushings came with "spacers" if I am understanding the term properly. Gerry's pic is really good. The 3524486 is longer than the 348080 without question. Both the rubber shoulder dimension AND the "spacer" length is different.


Discussion Starter · #13 ·
# 3 and #5 are the "oddballs"

#5 above the axle is simply a non bolted cushion.

#3 , the body has a fixed, threaded protruding lug that indexes in the the mount locating things.

All the rest have floating nut plates and offer no real locating until they are tightened up.

Now this is my wagon but I believe #3 to be the same on the Impala.
I will go in the attic later to check my Impala floor pan

Discussion Starter · #14 ·
I'm seeing a need to create a "sticky" on this and lock it down, but also a need to work on format if the thread is going to contain PN's. In reality, some of the parts are becoming extinct, so I'm not sure how much it will matter in the end.

Hag, looking at what you are holding from Dal, are you choosing to stay with OE Impala SS parts? No issue, just wanted to understand, since your list of items seems mixed--was it a matter of what was available, or something else?

As far as the cushion for #5, there are 2 PN's:

(again, refers to 94-96 cars)

488610 is used on 9C1 & wagon (discontinued, with no inventory)

556755 is used on Impala SS & all other B-sedans except 9C1
This part has been removed from GM inventory, but is available from Vintage Parts 877.846.8243 (Toll Free)

And, FWIW, it's not 100% that other cushions will fit in place of the part used in #5--they are somewhat different, and even though similar in dimensions, we can't be sure of how important the rubber durometer may be in that location.

An unloaded #5 (488610) is about 1.30" tall, and others range from 1.14" to 1.20" (all measurements unloaded). The #5 cushion has no metal molded into it, where all other body mounts do. The #5 cushion is designed to "pop" into position on the frame, with a molded lip/ridge.

In response to your question about PN 348080, used in #1 & #3 body mount positions on 94-96 9C1, I recommend using it in the #3 position. What I don't see on your list of items is the shorter bolt that should be used with this upper mount when used in the #3 position--but you can shorten existing bolts, I suppose.

[ 06-26-2007, 04:07 PM: Message edited by: Navy Lifer ]

Discussion Starter · #15 ·

Thanks for your response. I agree an updated sticky is probably needed, but you are correct my drivel would help no one, glad you figured it out.

When I called Dal, I just asked him for his best estimate of an SS ala 9C1 upgraded. So I didn't give him a specific "target". Just a "tighter" stock setup. #1 will hopefully become wife's grocery getter/baby hauler again. So my goal was "stock +". This is what he sent.

Shorter bolts? NP!!! :D shorter is MUCH easier than longer. My bolt stretcher works just as good as my wire stretcher: pretty P Poor
. I kept cutting it off, and cutting it off, and it was still too short. :cool:

I just havn't pulled #3's body off yet, so I don't have a good visual of the body/frame relationship. If using the 9C1 upper bushing in #3 position, does that not put more load on 1,2 (and 4 by default)? Or on the SS, did the #3 just get squished more to meet 1,2 and 4?

lol, didn't think about vintage parts.... coming to the realization that these babies are getting old.....

Thanks for the advice.

Discussion Starter · #16 ·

I think the concern about different upper cushion height is a non-issue. Once loaded, the characteristics of each/all are dictated by the amount of compression and the rubber durometer in each position. All of them will be "sandwiched" in full contact with the frame and body, even if the uncompressed thickness does vary.

Not knowing what method GM was using "back in the day" to determine what mounts were best to use in a specific model, and knowing that 9C1 & non-9C1 setups were different, it's impossible to say what the ultimate mounting system would be--this type of mount has been used for YEARS.

It would be interesting to have someone with the credentials dust off all the old data, re-evaluate it, and use some of the more recent methods of analyzing the behavior of the body & chassis, especially in light of suspension and wheel/tire trends and developments since the time the 9C1 and Impala SS were "calibrated" for production, way back in 1992 & 1993. Not likely to happen, so we work with what we have or take a SWAG at what might work better.

I still believe that the OE stuff is alot closer to what is needed than replacing the parts with polyurethane, but I'm also certain that there are new materials available today that could do better than the OE rubbber mounts--maybe we'll figure it out, eventually.

I need to add a comment--regarding my previous response, the measurement of the cushions did not include the thickness of the spacer for the "other than #5" mounts, so the true height of the upper cushions is closer to the same for all positions.

[ 06-26-2007, 07:35 PM: Message edited by: Navy Lifer ]

Discussion Starter · #17 ·

Thanks. I would love to have a wireframe and play with it in one of the FEA suits.

I understand what you are saying about the height vs strength. I was actually backwards hinting/probing, could that be a future problem of "over compression" of the softer/tallers to match the shorter stiffer. appears to be a wash.

Sounds like this is a wonderful friday night discussion around a fire, with a large group of enthusiasts and everyone's favorite adult beverage in endless supply!! :D (and no need to drive home that night, or designated drivers :rolleyes: )

agian thanks. Will let you all know how mine goes. Should start on it tonight.

Discussion Starter · #18 ·
Hi Everyone;

Hag, the reason I created this thread was to find out if there was an 'upgrade' available from the stock bushings in terms of stiffness but not as harsh as the Energy suspension kit which I also purchased but I am returning. No worries - your questions/info is more than relevant. Bolts are a concern - The # 3 position requires a different bolt because the floor boards are directly above the opening so the bolts would hit. The other areas have more room above so a longer bolt will work. With the 9c1 sleeves the long bolt sticks out a bit higher but should not be a problem.

As far as updating the proper specs/stats on bushings using the latest knowledge with a new sticky - that would be cool but I'm definitely not an expert. Hopefully someone else will have a few adult pops and decide its a worth endeavour.

So, I ordered and received two 9c1 upper bushings (pos 1-348080; 330942-6) and an OEM lower (377801) yesterday for testing purposes so I could compare all variables and try to determine which would provide the best fit for my project (and hopefully help others out down the road). Navy Lifer and 95wagon validly raised a concern about the combination of some of the parts used (ex. mueller mod).

So, now I have in my hands the following to be able to do comparisons and tests. These are measurements done without body weight loading but I did my best to be concise with what I did see.
* Old stock SS upper bushings (some in pretty good shape so I can use to do comparisons)
* Mueller bottom's - used the pink only for comparisons as the green ones were pretty much shot.
* New 9c1 upper's (positions 1 and 6).
* new 9c1/SS lowers.

I have used the Stock 9c1 Upper bushing and a stock 9c1/ss lower bushing as the reference.
* They mate together perfectly with 1/8" of space from the top of the central sleeve to the inside of the bottom bushing washer. The top of the bottom bushing is slightly collapsable so the bushing will not 'plow'. This is a proper fit for an upper/lower bushing. Picture next:

I did not include the distance from sleeve end to bottom of washer as I could not get a good picture of that (too dark).

Please keep in mind that I did my measurements without the frame so you need to mentally include that thickness between the upper and lower bushings. I will update this when I get the thickness of the frame walls between the bushings.

Some initial notes:
* The 9c1 upper bushing is harder than the stock SS but definitely not as hard as the Energy Suspension. (I checked this against my best shape 'old' ss one).
* The OEM lower bushing was quite firm (firmer than I thought it would be) but definitely not as firm as the ES (also known as granite <g>)
* The Mueller lower bushing felt harder to feel than the Stock OEM one, even with a number of years of life out of it - which matches the reasons why people went with them.
* Mueller lower bushing is taller than OEM lower bushing but OEM one has a angled upper part that has give which the mueller does not so it will plow earlier. See pic.

* The mueller bushing has a raised inside rubber step that is approx 3/8" higher than the stock 9c1/SS lower bushing from the bottom. Picture next (somewhat hard to tell - sorry).

* The additional height of the mueller bushing somewhat offsets this but then causes issues with the sleeve to inside lower washer distance. Using a long 'SS' sleeve with a 9c1 bushing may fix this but would increase the cost of this project as you would need to buy separate SS spacers. Futhermore, the inside raised part of the mueller has an angled part that causes it to plow with large upper bushing mating portion.
* As indicated by wagon95 the 9c1 sleeve is shorter than the SS one. This would cause the bolt to go a little further inside the body - don't think that's a problem. Pos 3 requires a 9c1 short bolt (pn 14085301) as there is no room for more bolt length.

What I have found is the following:
* With 9c1 OEM upper bushing and 9c1/SS OEM lower bushing the fit and finish is perfect. Spacing from sleeve end to inside of lower washer is 1/8" - perfect. I would highly recommend this option.
* The OEM lower bushing also seemed to fit ok overtop the SS OEM uppers so that option would also be fine (since my uppers raised portion were crushed I had to make a personal estimation but it seems correct as all SS's would come with this).
* with the 9c1 OEM upper and mueller pink as the lower I noticed a 1/2" space between the sleeve bottom and inside of lower washer. The overall fit of the mueller overtop of the 9c1 upper was ok and did not crush the raised middle portion in the upper like the SS upper was. Please note that this fit was a lot better than the SS/Mueller combination. Pictures next - unfortunately you can't see the inside sleeve distance very well.

* with the SS OEM lower and mueller pink there was a definite problem with the inner rubber sleeve fitting overtop of the rubber raised portion on the lower. The raised inner rubber on the mueller made contact with the SS raised rubber portion almost immediately. This raised rubber portion is wider than the 9C1. On most of my uppers this was crushed by the mueller. The distance between the sleeve and mueller was dependant on how much you crushed the upper inner rubber ring. On mine it was between 1/8" and 1/2". I would not recommend doing this.
!! I hit my limit in pics I can include so see next post Pic 1 for this pic.

!! See this pic in the next post - Pic 2)
(You can just make out where the inner sleeve ends below the washer)

Finally, I will edit this tomorrow and include a picture of my pos 5 'bushing'. It does not look like any bushing I have ever seen and I can't speak about what the 9c1 will look like. I am planning on getting the 9c1 or if its no longer available the I will re-use mine as they are in good shape.

I have updated my parts list at the top to include the stock 9c1/SS lower bushing.

Anyone can think of anything else they want me to check out while I have it all apart? Or any tests you want me to while I'm putting it together?

[ 06-28-2007, 03:01 PM: Message edited by: Gary Gevaert ]

Discussion Starter · #19 ·
The remaining Pics are:

Pic 1:

Pic 2:

By the way, you can see these pictures at full size at my 2007 project website listed in my signature or at Webshots website

[ 06-28-2007, 02:41 PM: Message edited by: Gary Gevaert ]

Discussion Starter · #20 ·

As Navy Lifer said, you appear to have a mixture of bushings. I guess that's Dal's mixture of bushings that give you a stock+. Would be interesting to ask him why this combo and whether the 9c1 setup would then be stock++. Although I'm also concerned as I did find that the SS OEM bushings did not fit properly with the mueller lowers (fit and spacing).

I'm guessing that the 348080 would go in position 3.

Also, as Navy Lifer indicated, the #5 is radically different than the other bushings. I'll post a pic in the next day or so.
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