Convertible body mounts, rubber or poly? - Impala Tech
Convertibles Convertible Q&A's

 
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post #1 of 18 (permalink) Old 01-01-2020, 04:35 AM Thread Starter
 
 
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Convertible body mounts, rubber or poly?

I plan on replacing the body mounts on my 69 convertible.

The question is should I go poly or rubber? I tried to search for info on old threads but nothing really on convertibles. I read something that the rubber on the repro bushings is not that great and rots again in 10 years. But I think that thread was pretty old, has the quality gotten any better over the years? I don't really mind changing them again in 10 years. What I do want to know is what do you think is better for the longevity of the body?

I do plan on putting poly bushings on the front control arms and strut rods, and my sway bar already has poly on it. I do plan on running just stock suspension and shocks and I use 15" tires with lots of sidewall. But the roads around here are kinda rough.

Then there is the question of wich set is correct. The assembly manual for the 69 shows that the convertible has 3 blind bushings per side and my car has them like that (well they have been changed in the 80's when it was frame off restored so who knows what was there originally) But when I look at sets from classic industries the 69-70 has only 2 blind ones per side and the 67-68 has 3 blind ones per side, but one of the smaller bushings is a little different?

https://www.classicindustries.com/pr...s/bm1008b.html

https://www.classicindustries.com/pr...s/bm1006b.html

Could it be that if my car was made early in the year the correct set could be the 67-68 one?
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post #2 of 18 (permalink) Old 01-01-2020, 02:11 PM
BA.
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Sorry man but I've got no insight on the blind bushing stuff.

Just noting that I personally prefer (and bought) the rubber bushings for my Vert because I valued the shock absorbing properties more than the less body roll/flex of the poly mounts. I live in Ohio and the roads aren't always great.

HOW A NOVICE REBUILDS A 66 IMPALA CONVERTIBLE:
http://www.impalas.net/forums/blog.php?u=1432
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post #3 of 18 (permalink) Old 01-01-2020, 02:17 PM
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I ordered the poly bushings from Energy and just one look at them I knew they wouldn't work. Number of bushings, diameters, fasteners, etc. we're all wrong. It's a generic set of bushings and not specific to my car ('68 convertible) at all. I sent it back and got the rubber bushings and have not had any issues.

Take note that these bushing sets typically do not include the 2 bushings for the radiator core support for some reason. You'll also need to loosen the core supports when replacing the other bushings to prevent damaging your front fenders.

The only problem I had when replacing mine were the ones at the very back of the frame - the bolts were fused to the weld nuts on the body and there is no access to them. They broke loose and just spun, so I had to drill access holes in the trunk floor and then used blind grommets to seal the holes. See attached pics.
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1968 Impala SS
496 Stroker
T56 Conversion
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post #4 of 18 (permalink) Old 01-02-2020, 10:15 PM Thread Starter
 
 
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Quote:
Originally Posted by 68WASAGOODYEAR View Post
I ordered the poly bushings from Energy and just one look at them I knew they wouldn't work. Number of bushings, diameters, fasteners, etc. we're all wrong. It's a generic set of bushings and not specific to my car ('68 convertible) at all. I sent it back and got the rubber bushings and have not had any issues.

Take note that these bushing sets typically do not include the 2 bushings for the radiator core support for some reason. You'll also need to loosen the core supports when replacing the other bushings to prevent damaging your front fenders.

The only problem I had when replacing mine were the ones at the very back of the frame - the bolts were fused to the weld nuts on the body and there is no access to them. They broke loose and just spun, so I had to drill access holes in the trunk floor and then used blind grommets to seal the holes. See attached pics.
Thanks for the info. I ordered rubber ones for a 68, I just have a gut feeling that they will fit better in my case.

I have the whole front end of the car removed so it is not a problem, I'll deal with the radiator support bushings later. I still have to uncouple the gas tank, steering and brakes. Speedo cable and the e-brake cable are already removed.

Any other tips on lifting the body, like where are the good places to lift? And do rubber bushings need any grease? Should I loctite the bolts and or use a torque wrench even?

69 Impala Convertible - It's not perfect, but it's mine https://www.instagram.com/stedisgarage/
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post #5 of 18 (permalink) Old 01-03-2020, 09:23 AM
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Quote:
Originally Posted by Stedi View Post
Quote:
Originally Posted by 68WASAGOODYEAR View Post
I ordered the poly bushings from Energy and just one look at them I knew they wouldn't work. Number of bushings, diameters, fasteners, etc. we're all wrong. It's a generic set of bushings and not specific to my car ('68 convertible) at all. I sent it back and got the rubber bushings and have not had any issues.

Take note that these bushing sets typically do not include the 2 bushings for the radiator core support for some reason. You'll also need to loosen the core supports when replacing the other bushings to prevent damaging your front fenders.

The only problem I had when replacing mine were the ones at the very back of the frame - the bolts were fused to the weld nuts on the body and there is no access to them. They broke loose and just spun, so I had to drill access holes in the trunk floor and then used blind grommets to seal the holes. See attached pics.
Thanks for the info. I ordered rubber ones for a 68, I just have a gut feeling that they will fit better in my case.

I have the whole front end of the car removed so it is not a problem, I'll deal with the radiator support bushings later. I still have to uncouple the gas tank, steering and brakes. Speedo cable and the e-brake cable are already removed.

Any other tips on lifting the body, like where are the good places to lift? And do rubber bushings need any grease? Should I loctite the bolts and or use a torque wrench even?
Take a close look at your floor pans - avoid lifting in the middle of the pans if there is any question of their integrity. I used a 2*10*10 piece of plywood in between the floor jack and car body to spread out the load as much as possible. Wood is your friend here - it's great in compression, but will still give a little. If you have the front of the car removed, you shouldn't have any problems. The mounts near where the firewall meets the front fenders were the worst, most unnerving ones to replace. I didn't use grease or anything, just some blue loctite on the fasteners.

1968 Impala SS
496 Stroker
T56 Conversion
3.73 Posi-Trac
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post #6 of 18 (permalink) Old 01-03-2020, 09:49 AM
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Before you take it apart it is a good idea to drill an eighth inch hole through the parts to align everything again with a drill bit (hood tinges, fender tabs, any place where the two metal pieces are close together).

Big Dave
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post #7 of 18 (permalink) Old 01-03-2020, 10:58 PM Thread Starter
 
 
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Quote:
Originally Posted by 68WASAGOODYEAR View Post
Take a close look at your floor pans - avoid lifting in the middle of the pans if there is any question of their integrity. I used a 2*10*10 piece of plywood in between the floor jack and car body to spread out the load as much as possible. Wood is your friend here - it's great in compression, but will still give a little. If you have the front of the car removed, you shouldn't have any problems. The mounts near where the firewall meets the front fenders were the worst, most unnerving ones to replace. I didn't use grease or anything, just some blue loctite on the fasteners.
I was looking at those two mounts near the firewall and was thinking that they look the easiest, I am most nervous about the one under the door

Quote:
Originally Posted by Big Dave View Post
Before you take it apart it is a good idea to drill an eighth inch hole through the parts to align everything again with a drill bit (hood tinges, fender tabs, any place where the two metal pieces are close together).

Big Dave
I probably would have done this, but the alignment was already all over the place and I have to start from scratch anyway.

This might be a stupid question but when I'm lifting the body the top should probably be closed yes?

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post #8 of 18 (permalink) Old 01-04-2020, 07:22 PM
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The top doesn't provide much if any structural support to the car. That's what the boxed frame is for. Also, those little wedges in the door jamb with the matching striker plate on the doors? Those are convertible-only and turn the doors into a structural component when you close them. Whatever you do, do not lose them during the body work. They are not reproduced and I've only seen a single set of them on eBay and they were not cheap. Yes, I bought them as they were missing from my car.

Top up or down I don't think matters. I would definitely close the doors.

1968 Impala SS
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T56 Conversion
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post #9 of 18 (permalink) Old 01-06-2020, 07:51 AM
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You have a picture of those by any chance? It'd be nice to know if I'm missing something.

Quote:
Originally Posted by 68WASAGOODYEAR View Post
The top doesn't provide much if any structural support to the car. That's what the boxed frame is for. Also, those little wedges in the door jamb with the matching striker plate on the doors? Those are convertible-only and turn the doors into a structural component when you close them. Whatever you do, do not lose them during the body work. They are not reproduced and I've only seen a single set of them on eBay and they were not cheap. Yes, I bought them as they were missing from my car.

Top up or down I don't think matters. I would definitely close the doors.

1969 Impala convertible build thread here:
https://www.pro-touring.com/threads/...ghlight=impala
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post #10 of 18 (permalink) Old 01-06-2020, 08:20 AM
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Quote:
Originally Posted by justjohn View Post
You have a picture of those by any chance? It'd be nice to know if I'm missing something.

Quote:
Originally Posted by 68WASAGOODYEAR View Post
The top doesn't provide much if any structural support to the car. That's what the boxed frame is for. Also, those little wedges in the door jamb with the matching striker plate on the doors? Those are convertible-only and turn the doors into a structural component when you close them. Whatever you do, do not lose them during the body work. They are not reproduced and I've only seen a single set of them on eBay and they were not cheap. Yes, I bought them as they were missing from my car.

Top up or down I don't think matters. I would definitely close the doors.
Sure. I'll post some pics in this reply when I get home tonight.

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post #11 of 18 (permalink) Old 01-06-2020, 08:20 AM
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I'd use rubber.




Ted
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post #12 of 18 (permalink) Old 01-06-2020, 05:57 PM
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Pics attached.
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1968 Impala SS
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post #13 of 18 (permalink) Old 01-07-2020, 08:06 AM
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Quote:
Originally Posted by 68WASAGOODYEAR View Post
Pics attached.
Thanks. I vaguely remember those. Of course I'll check when I get home tonight.

1969 Impala convertible build thread here:
https://www.pro-touring.com/threads/...ghlight=impala
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post #14 of 18 (permalink) Old 01-16-2020, 07:25 PM Thread Starter
 
 
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Seems like I've hit a little snag.

I received the body mount kit today and I started to open the bolts and checking out what goes where I noticed that I have the same problem as in this thread:

https://www.impalas.net/forums/8-res...html#post12923

The body mounts are indeed a little weird, I attached a few photos. Seems like the bottom part was gnawed out by the last person who wanted to swap the mounts.

I am not sure if this is even that big of a problem though, the new round one should fit pretty snug, and worse case I will have to reuse the old bottom part temporarily.

I got an OER set and the new rubber is super stiff compared to the old one, is this normal?
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post #15 of 18 (permalink) Old 01-17-2020, 09:16 AM
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I do remember that damn square mount when I did mine, but I can't remember what I did about it. I think the new bushing was big enough to slip over it and then the bolt went through the middle? I might have used a large fender washer to make the bolt work through the middle of the square hole. I'll have to look. The rubber will soften up with use. The ones you took out are likely decades old and dry rotted.

1968 Impala SS
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T56 Conversion
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post #16 of 18 (permalink) Old 01-19-2020, 01:42 AM Thread Starter
 
 
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I had a little surprise on the passenger side when I went to loosen the bolts there. The square hole mount had no bottom part to be seen anywhere and the bolt is broken. It has some thread visible as it didn't break into the nut so I might be able to get it out. This position seems the be a real problem if I have to put in a new nut somehow.

I did swap all the drivers side mounts though. But the body didn't go back down all the way on all the mounts. Positions 1, 2 & 6 are floating, #6 especially big gap. I think I'll swap the passenger side and see how it settles after that.

The square hole mount fit very well, I have to figure out the bottom part for it though.

All the mounts that were on the car were #3906748 (except the square hole) and the bottom part was #3962720 (except square hole which had actually a #3906748 that was gnawed out) So I guess those were available when they were swapped in the 80's
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post #17 of 18 (permalink) Old 06-25-2020, 02:50 AM
 
 
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I have the poly ones from Energy Suspension also, and I'm pleased with them.
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post #18 of 18 (permalink) Old 06-25-2020, 08:31 AM
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I have the Prothane bushings on order for my 69 convertible.

1969 Impala convertible build thread here:
https://www.pro-touring.com/threads/...ghlight=impala
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