Does anyone except GM provide HD rubber body bushings?

maybe a different question or two will work--

Who is the supplier for GM rubber body bushings?

Is there a good non-OEM body mount that is not quite as hard as poly graphite or poly urathane?

hey man, i checked with some old GM buddies back east and they all said GM only or the urethane route. i now there was a company awhile back, checked on them, their gone now

Here are the GM part numbers (I think)

position________Upper_____________________Lower
#1_87, 88______1255795_drk blue/white____348080 green/yellow
#1_86 +prior___14034780_blue_____________457941 drk blue/white
#2_____________10005267__green___________457941 drk blue/white
#3_____________330951_orange_____________3778012
#4_____________330951_orange_____________457915 pink
#5_____________488610_grey_______________(none)
#6_____________348080_green/yellow_______377801 black
#7_____________14032560_orange/yellow____377801 black

Are there any older or newer GM part numbers that might be usable for our cars?

several of these bushings are no longer available

Hi MM,

We've been trading some PM's on this topic via this site - and now is probably the time to broaden the readership.

The best characteristics of body bushings from an NVH perspective are very low stiffness, and high loss factor.

The best characteristic of body bushings in terms of deriving maximum benefit from the body in order stiffen the part of the car the suspension is attached to, namely, the frame, is to use the highest stiffness possible. High loss factor helps here too.

As tire and spring designs are trending stiffer and stiffer with the passing years, the lack of stiffness in the A/G body frame (designed in 1975 as essentially a carry-over from designs of decades prior,) is generally becoming more apparent to the driver. This increases the motivation to use the stiffest body bushings possible. Again, high loss factor is always a benefit.

So you can see we are left with a profound conflict: do we want high stiffness for good handling and a feeling of chassis "tightness," or do we want low stiffness for a comfortable ride with good NVH properties. Further, material properties generally vary so that high stiffness comes with low loss factor, and vice-versa.

(One note about PU: polyurethane can be tweaked to have a huge range of material properties. The kind used for most aftermarket body bushing applications is very stiff and has low loss. But I've worked with very soft variants (E=1MPa, tan(delta)=0.25,) that would better match OEM rubber. N.B.: most modern body bushings are made from butyl rubber, as opposed to natural rubber in the "old days." I'm not sure when the "old days" ended, so A/G body bushing material composition is unknown to me; 1975-1988 could have been in a transition period for all I know.)

The "either/or" bushing dilemma can only be solved by radical changes to the fundamental structure of the car, such as radically increasing frame stiffness, or by eliminating them altogether by converting the car to a unibody design.

One further comment for now: I've found the best overall compromise for my taste, to be to use stiff bushings at the four corners of the car, combined with soft OEM rubber everywhere else. It's not a very good compromise, but it's probably the best that can be hoped for short of radical surgery, to achieve the mutually-exclusive aims I spoke of.

Best,
MAP

Thanks Mark,

Mark's postings on this subject are some of the best around. As he has stated, these results must also be combined with what you do on front and rear suspension as well as what tires you run.

Finally, it depends on what you are using the car for and how much you care about Noise, Vibration, and Handling (NVH).

I am working on finding a source for replacements for OEM. If anyone has a source, it would be welcome.

O.K. guys, i went through my "little black book" and none of the companies i used to deal with make anything in the factory style bushings. apparently Prothane makes a little softer body bushing than Energy Suspension does, but i can't trace down the exact material either uses, company secrets i imagine.

Pricey, but what about G Body Parts?
http://www.gbodyparts.com/product_info.p...196f95562c1aec6

Listed as GM units.

In general Regals and Monte Carlos are slightly different body mounts for the uppers.

Mount Cutlass Regal Monte Cutlass Regal Monte
LocationUpper Upper Upper Lower Lower Lower
2 356561 330986 10005267 457915 457915 457941
3 330942 348080 330951 377801 377801 377801
4 348080 348080 330951 457915 457915 457915
5 556755 None 488610 None None None
6 330951 330942 488610 377801 377801 377801
7 25500592 1242754 14032560 377801 377801 377801

Perhaps the GNational was different. I am not sure. Perhaps the Regal is close enough. In general, Buicks were set up to be a softer ride than the Chevy.

I will try contacting them to see if they will tell me the part numbers in the kit.

Hopefully this will be easier to read

Mount Cutlass Regal Monte Cutlass Regal Monte
Location Upper Upper Upper Lower Lower Lower
2 356561 330986 10005267 457915 457915 457941
3 330942 348080 330951 377801 377801 377801
4 348080 348080 330951 457915 457915 457915
5 556755 None 488610 None None None
6 330951 330942 488610 377801 377801 377801
7 25500592 1242754 14032560 377801 377801 377801

Nope

One more time

Mount____Cutlass__Regal___Monte____Cutlass__Regal___Monte
Location_Upper____Upper___Upper____Lower____Lower___Lower
2________356561___330986__10005267_457915___457915__457941
3________330942___348080__330951___377801___377801__377801
4________348080___348080__330951___457915___457915__457915
5________556755___None____488610___None_____None____None
6________330951___330942__488610___377801___377801__377801
7________25500592_1242754_14032560_377801___377801__377801

Victory!

Dixie has them at quite a price

http://dixiemontecarlo.com/items/DM94016.html

rmsautoparts.com has lowers for 54.35 doesnt have monte pos 2 but cutlass and regal has the regal uppers for 47 for all but pos #7

All Gbody Buicks except GNXs did not get all the body mount bushings like the MCs did. The first handling upgrade for a Gbody Buick is to install the missing body bushings that GM did not install. Buick claimed that not installing some of the bushings gave their cars a softer ride. So a stock body bushing set for a Regal probably won't be complete for a MC.

Thanks George. I will check it out.

Will-- did the GN actually get all of the bushings, perhaps even stiffer than the MC?

the only Buick that got all the bushings was the 1987 GNX.. the regular Regals and GN's had a bunch of missing bushings- my 84 T Type (essentially a GN with blue paint and no spoiler on the trunk) actually has a few spots where there is an upper bushing but no lower bushing.

Most of the Gbody Buicks, even GNs either had 4 to 6 lower body bushings not installed, my n/a Regal Limited had 4 missing lower body bushings, but I installed those 4 lower bushings which did improve the handling.

Hi Folks,

Here's something of a primer about selecting materials for bushings:

http://machinedesign.com/ContentItem/61978/Shockaweandvibration.aspx

A bushing has two important properties: stiffness and dampening. Assuming the translational modes are the only ones that count (which is true for body bushings,) then the bushing behaves as a spring shunted by a viscous loss dampener (i.e., a shock absorber,) in x,y,z. That's why if the bushing is made from a single piece of material, then the material should be viscoelastic.

For best mechanical isolation, the lowest possible stiffness, combined with high loss factor, are important. (That's why some of the non-MCSS G-bodies have missing bushings - there's no cheaper way to decrease stiffness than to delete bushings!) But as previously stated, what's good for mechanical isolation is bad for chassis dynamic behavior, and vice-versa - that's because for most body-on-frame cars, such as our G bodies, most of the chassis stiffness is derived from the body, and not the frame. If the frame "floats" with respect to the body, then the suspension doesn't act as it should, and the result is vague, uncontrolled, "weird" handling. In short, our G body frames desperately need stiff coupling with the body so that the modern tendency toward stiff tires/springs/shocks/swaybars can work at least passably well with our cars.

But you ultimately need to make the judgment call between good handling and bad NVH (Noise, Vibration, Harshness,) or its converse. Your mileage may vary: NVH perception is notoriously subjective, but it can probably be said that many enthusiasts reading here would most likely veer in the direction of poorer NVH but better handling, as opposed to the original factory design. This would indicate stiffer bushings than stock; but again, stiff or not stiff, we want high loss factor. Exactly 100% of the aftermarket PU body bushings I've seen fail miserably in this regard.

Best,
MAP

This has been very helpful.

MAP, do you have a recommendation for the harder bushings in positions 1 and 7 (manufacturer, material, etc.)?

What size would you use in those positions --both upper and lower?

Hi MM,

I found one location where I wrote about these bushings in detail:

http://www.montecarloss.com/community/ub...true#Post486863

I'm unaware of anyone that manufactures these bushings, so you'd have to make your own. Plus - read the full text of this thread, since it describes one of the potential pitfalls of using stiff bushings at the corners of the car.

I like Delrin (acetal) for this bushing since it has attractive material properties for this application: reasonable modulus, low creep, low moisture absorption, and low mass density. It's also an electrical insulator, which avoids the galvanic action problems of using dissimilar metals in close contact. A disadvantage of Delrin is that it's one of the pricier plastics out there, so you might want to consider an alternative (possibly Nylon, but this is mostly uncharted territory for me. I wouldn't use HDPE, but that's opinion more than fact. Someone claimed success here several years ago using plain PVC.)

Best,
MAP

How different are poly urethane or poly graphite bushings from these?

Is the only way to have delrin mounts to make them yourself?

Also, is there a place I could get enought delrin to make these 8 mounts but not have to buy a large $250 sheet to do it?