Original spec B body mounts. Are they still available?
cdnpont said
Aug 30, 2014
I had always had it in the back of my mind that at some point, I'd like to probably replace the body mounts on my 67.
Yesterday, while changing my diff lube, I had the car up, with the axle supported on stands, and the front wheels on ramps. At one point when I pulled myself out from under the car holding the back bumper, I heard a thunk or knock. I can move the bumper up and down slightly and hear a knock. It appears the rearward mounts (#7) are shot and are not cushioning the body to frame in any way. I have heard this clunk on the road and wondered about it.
Can good quality stock rubber replacement mounts (not poly) be bought for our B bodies? Anyone have any experience changing them, and any comments on the quality?
I see that the #7 mount upper has a GM# of 3926945, and the lower 3868996.
Mark, if you haven't done already, just call your local dealer and give them the numbers? That would be the easiest to do and go from there... I'm sure there must be repops out there... Did you type the p/n on an ebay search... That to i'ved done before with great results!
One of these days I will have to add position #3 rubbers to my Rag... Forgot and never thought about it since I replaced the frame with a 4-dr one back in '88ish... Oh well, no ill effects to date.. (lol)
-- Edited by 67Poncho on Saturday 30th of August 2014 12:03:34 PM
2qwik2c said
Aug 30, 2014
The 3926945 mounts were used on 68-72? Chevelles as well. They are not that hard to find NOS either, they come up On eBay often. I would try to find them from a chevelle supplier as they seem to be made from a better material for the chevelles. Maybe NOS can get them for you? I ve heard mixed results on the repop aftermarket impala kits, some don't fit in the frame holes properly and are made of a cheap material that deteriate rather quickly.
427carl said
Aug 30, 2014
I just changed the rears on a 66
Original re-pros seem to squish down (according to Uncle Bernie who replaced his in Lemans )
read the B-Body sites re-pros are not recommended (as they are not made to OE 66-67 specs)
2qwik2c said
Dec 6, 2014
Not one of those poly bushings even look close to the originals. I wonder if the heights of them are even close?
427carl said
Dec 6, 2014
They are a perfect fit in the back of my 1966 B-Body I'd rather have a black poly working well than a re-pro all squished down (2 cents)
2qwik2c said
Dec 6, 2014
Yes for sure, I heard the same thing about the repro's.
cdnpont said
Dec 6, 2014
I bought a set of offshore mounts. I should have talked to NOS, but at first glance everything looks good.
But the one thing that makes me suspicious believe it or not, is the smell of the rubber. Yea, the smell! I'm sure most here know what I mean. you know that cheap, princess auto rubber item smell? Yea, these are just like that!
We'll see. I'll just do the rearmost and see how that goes.
I bought a set of offshore mounts. I should have talked to NOS, but at first glance everything looks good.
But the one thing that makes me suspicious believe it or not, is the smell of the rubber. Yea, the smell! I'm sure most here know what I mean. you know that cheap, princess auto rubber item smell? Yea, these are just like that!
We'll see. I'll just do the rearmost and see how that goes.
Can you do me a favour and tell me what the heights of the repro bushings are for there respective locations?? I'm curious to see how close they are to my NOS ones. I may need a set.
427carl said
Dec 6, 2014
I will do that for you
I was just going over them, to replace the rad supports....
I have them all except the rears (installed)
"Aluminum body mounts are too harsh for street use and tend to break, causing damage to other parts.
Original rubber mounts are so soft that they crack, distort, crush, and often fall off.
Energy Suspension's specially formulated polyurethane body mount sets combine the best qualities of both--they're soft enough for a smooth ride, and yet rugged enough for the most demanding road or track.
Most have a steel ring molded into the end for added durability."
-- Edited by 427carl on Saturday 6th of December 2014 08:30:48 PM
NOS said
Dec 6, 2014
NOS wrote:
Body mount kit pn 318BM1005B for 67 B- body $87.50
BM1005B - 1967-68 IMPALA / FULL SIZE 2 DOOR HARDTOP / SEDAN BODY MOUNT BUSHING SET
OEM reproduction subframe bushing set.
Each pre-packaged set contains all shouldered rubber bushings and biscuit. Each body mount is produced using correct compression molded S.B.R. rubber
Dale @ NOS a poncho supporter
I will get an explanation for S.B.R rubber cause I would like to also know
427carl said
Dec 7, 2014
For many purposes SBR directly replaces natural rubber, the choice depending simply on economics.
Its particular advantages include "excellent" abrasion resistance, crack resistance, and generally better aging characteristics.
Like natural rubber, SBR is swollen and weakened by hydrocarbon oils and is degraded over time by atmospheric oxygen and ozone.
In SBR, however, the main effect of oxidation is increased interlinking of the polymer chains, so, unlike natural rubber, it tends to harden with age instead of softening.
The most important limitations of SBR are poor strength without reinforcement by fillers such as carbon black (although with carbon black it is quite strong and abrasion-resistant), low resilience, low tear strength (particularly at high temperatures), and poor tack (i.e., it is not tacky or sticky to the touch).
These characteristics determine the use of the rubber in tire treads; essentially, its proportions decrease as the need for heat resistance increases until 100 percent natural rubber is reached in the heaviest and most severe uses, such as tires for buses and aircraft.
sr-71 said
Feb 7, 2015
I'm new this forum but if anyone is interested I have some NOS GM mounts that have been in cool dry storage for the last 30+ years. Part number on them is 3926945. I bought them for a GTO restoration in the 80s and were incorrect for the application.
409Safari said
Apr 3, 2015
sr-71 wrote:
I'm new this forum but if anyone is interested I have some NOS GM mounts that have been in cool dry storage for the last 30+ years. Part number on them is 3926945. I bought them for a GTO restoration in the 80s and were incorrect for the application.
Welcome to the site! Here you can see applications for those body mounts # 3926945.
Thanks for the part lookup Pierre, looks like SR71's oem mount is for the #7 position, 65-70.
I've pm'd him in the hope. But he's only one post, on Feb 7th.
409Safari said
Apr 3, 2015
cdnpont wrote:
Thanks for the part lookup Pierre, looks like SR71's oem mount is for the #7 position, 65-70.
I've pm'd him in the hope. But he's only one post, on Feb 7th.
And #1-2 upper I think.............know that the post is old but give the info anyway and most of all, I love to post these diagrams and pages from the shop manual so, all the pleasure is for myself ...........LOL
I had always had it in the back of my mind that at some point, I'd like to probably replace the body mounts on my 67.
Yesterday, while changing my diff lube, I had the car up, with the axle supported on stands, and the front wheels on ramps. At one point when I pulled myself out from under the car holding the back bumper, I heard a thunk or knock. I can move the bumper up and down slightly and hear a knock. It appears the rearward mounts (#7) are shot and are not cushioning the body to frame in any way. I have heard this clunk on the road and wondered about it.
Can good quality stock rubber replacement mounts (not poly) be bought for our B bodies? Anyone have any experience changing them, and any comments on the quality?
I see that the #7 mount upper has a GM# of 3926945, and the lower 3868996.
Cheers, Mark
Mark, if you haven't done already, just call your local dealer and give them the numbers? That would be the easiest to do and go from there... I'm sure there must be repops out there... Did you type the p/n on an ebay search... That to i'ved done before with great results!
One of these days I will have to add position #3 rubbers to my Rag... Forgot and never thought about it since I replaced the frame with a 4-dr one back in '88ish... Oh well, no ill effects to date.. (lol)
-- Edited by 67Poncho on Saturday 30th of August 2014 12:03:34 PM
The 3926945 mounts were used on 68-72? Chevelles as well. They are not that hard to find NOS either, they come up On eBay often. I would try to find them from a chevelle supplier as they seem to be made from a better material for the chevelles. Maybe NOS can get them for you? I ve heard mixed results on the repop aftermarket impala kits, some don't fit in the frame holes properly and are made of a cheap material that deteriate rather quickly.
I just changed the rears on a 66
Original re-pros seem to squish down (according to Uncle Bernie who replaced his in Lemans )
I bought a kit and used 2
your welcome to 2 or more if you like.....
just saying
read the B-Body sites re-pros are not recommended (as they are not made to OE 66-67 specs)
Not one of those poly bushings even look close to the originals. I wonder if the heights of them are even close?
They are a perfect fit in the back of my 1966 B-Body I'd rather have a black poly working well than a re-pro all squished down (2 cents)
Yes for sure, I heard the same thing about the repro's.
I bought a set of offshore mounts. I should have talked to NOS, but at first glance everything looks good.
But the one thing that makes me suspicious believe it or not, is the smell of the rubber. Yea, the smell! I'm sure most here know what I mean. you know that cheap, princess auto rubber item smell? Yea, these are just like that!
We'll see. I'll just do the rearmost and see how that goes.
Body mount kit pn 318BM1005B for 67 B- body $87.50
BM1005B - 1967-68 IMPALA / FULL SIZE 2 DOOR HARDTOP / SEDAN BODY MOUNT BUSHING SET
OEM reproduction subframe bushing set.
Each pre-packaged set contains all shouldered rubber bushings and biscuit. Each body mount is produced using correct compression molded S.B.R. rubber
Dale @ NOS a poncho supporter
Molded SRB rubber
Can you do me a favour and tell me what the heights of the repro bushings are for there respective locations?? I'm curious to see how close they are to my NOS ones. I may need a set.
I will do that for you
I was just going over them, to replace the rad supports....
I have them all except the rears (installed)
"Aluminum body mounts are too harsh for street use and tend to break, causing damage to other parts.
Original rubber mounts are so soft that they crack, distort, crush, and often fall off.
Energy Suspension's specially formulated polyurethane body mount sets combine the best qualities of both--they're soft enough for a smooth ride, and yet rugged enough for the most demanding road or track.
Most have a steel ring molded into the end for added durability."
-- Edited by 427carl on Saturday 6th of December 2014 08:30:48 PM
I will get an explanation for S.B.R rubber cause I would like to also know
For many purposes SBR directly replaces natural rubber, the choice depending simply on economics.
Its particular advantages include "excellent" abrasion resistance, crack resistance, and generally better aging characteristics.
Like natural rubber, SBR is swollen and weakened by hydrocarbon oils and is degraded over time by atmospheric oxygen and ozone.
In SBR, however, the main effect of oxidation is increased interlinking of the polymer chains, so, unlike natural rubber, it tends to harden with age instead of softening.
The most important limitations of SBR are poor strength without reinforcement by fillers such as carbon black (although with carbon black it is quite strong and abrasion-resistant), low resilience, low tear strength (particularly at high temperatures), and poor tack (i.e., it is not tacky or sticky to the touch).
These characteristics determine the use of the rubber in tire treads; essentially, its proportions decrease as the need for heat resistance increases until 100 percent natural rubber is reached in the heaviest and most severe uses, such as tires for buses and aircraft.
Welcome to the site! Here you can see applications for those body mounts # 3926945.
Thanks for the part lookup Pierre, looks like SR71's oem mount is for the #7 position, 65-70.
I've pm'd him in the hope. But he's only one post, on Feb 7th.
And #1-2 upper I think.............know that the post is old but give the info anyway and most of all, I love to post these diagrams and pages from the shop manual so, all the pleasure is for myself ...........LOL