Hello,

The rear (#4) body mounts on my 1975 Coupe are completely rusted, including the upper metal reinforcements. However, the lower brackets welded to the frame are in good shape. I haven't found much information online about this specific job, so before I begin, I'd like to confirm a few things.

I've reviewed two articles that cover the replacement procedure:
1963-1982 Corvette Body Mount Replacement Part 1 | Corvette Magazine
1963-1982 Corvette Body Mount Replacement Part 3 | Corvette Magazine

1. Can this be done without lifting the body? Or is it safe to lift just the rear slightly, maybe half an inch, in case more space is needed to insert the new bushings? Without having to unbolt anything else on the car.
2. After removing the bushings and cutting the bolts, should I place something solid between the bracket and the body, considering it won't be a one-day job?
3. Is the nut and cage where the bolt goes accessible from the interior of the car? Not sure about the exact location & it seems that there's a convertible in above mentioned articles...
4. Would you recommend purchasing these sets from bairscorvette? Will their C3 (1968-1982) Body Mount Kits include everything needed, or should I acquire additional items for the job?

Bair's - C3 (1968-1982) Body Mount Kits (bairscorvette.com)


5. Do you have any recommendations or best practices specifically for this job?

Thanks in advance for any guidance or advice you can provide!

 

1.. No but you can modify the new reinforcements slightly to get it to go into place without removing the body.
2.. Yes or just shim between the frame and the body in that general area. No load or twisting = no problem without the mount for a little while
3.. If it's a couple then the nut is accessible from inside the car. Awkward but accessible
4.. Only you can tell what you need. The kit does seem complete though

Here's how I dealt with mine at one point. father down in the thread is the change of the mount, the top part was mainly about dealing with the nut
https://www.corvetteforum.com/forums...oval-tool.html

M

 

Thanks for the response, much appreciated!

Regarding the point 4., I just wanted to make sure that I'm getting all parts needed just for this particular job. Hoping not to broke anything in the process, or find something else that is broken :-)

By the way, I've stumbled upon this topic:
Rear body mount question | Corvette Forum : DigitalCorvettes.com Corvette Forums

In particular:
What do you think about this? Looks like it could make the repair a bit easier...

 

On my 78 the cage nut was impossible to break loose. The cage itself was spinning. So I cut it off and just put a box wrench on the nut inside the car and wedged it in place. Then I went underneath and was able to unbolt it. When I put it back together I did the same but I didn't bother putting the cage back in.
On mine that was the only rust issue and I never could figure out how water got in that well in the back to let it rust. Good luck.

 

It's fairly accessible but another person to hold the inside nut is a must (ok I did it without but I shouldn't have)
It's been a while but I don't know really what advantage there is to putting the bolt in down from the top. Ultimately it doesn't matter which way it goes.
M

 

I'm changing the #4 BM on my '71 currently. Is there supposed to be a aluminum spacer between the metal reinforcement bracket and the fiberglass body?

My body is off the frame, so I can't answer most your questions. I'm going to rivet my nut cage in, then rivet the reinforcement brackets back on the body. I'm not planning to bother with the original assemble rivets, seems impossible to use! Just going to use normal rivets.

 

I recently did all my body mounts. If your number 4's are that bad, what do your number 1's look like? There exposed to the elements as well. Mine where pretty bad indeed!
48 year old car, 48 year old rubber mounts.
doing just the number 4's seems like cutting to many corners.

 

[QUOTE=Arg0413;1607283112]I'm changing the #4 BM on my '71 currently. Is there supposed to be a aluminum spacer between the metal reinforcement bracket and the fiberglass body?
...

Yes, the 68-72 used aluminum spacers and then they went to rubber (slightly thicker)
M

 

[QUOTE=Mooser;1607283234]Interesting: One had an aluminum spacer and the other didn't - appeared they filled the bracket with VPA to take up the space!!! The things people do to these cars!

Do you know the correct thickness of the spacers? Why doesn't anyone sell them new?

 

Wait, I thought you meant between the mount and the reinforcement riveted to the body. Are you saying there was a spacer between the reinforcement and the body? Not that I know of
M

 

I thought there was one between the reinforcement and the body - it fell to the ground and I had an old body mount spacer nearby! I wasn't sure. The drivers side I removed this evening didn't have one. So you just answered my question and confirmed that nothing goes in between the reinforcement and the body. Thanks!

 

Check the condition of the glass under the reinforcement. If it's all solid you're good to go. If its at all weak/cracked the adding something between them won't hurt (I did since I cut the inner part of the reinforcement off
M

 

I was thinking that it'll be easier in a way that I won't have mess arround in that confined space with the cage and rivets - just feed the bolt down (maybe add a washer) & block it with a ratchet, then just work outside of the car.

I've inspected #1 front mount as well and it's in decent condition, I mean, in a sense that I haven't put it in "requires immediate attention" category. Thing is, with two little kids to look after, I can't spend that much time working on my Vette... I usually allocate few hours here & there, sometimes, I spend these few hours just on loosening single bolt... :-) So I'm prioritizing the repairs in a way that the Vette will be ready to pass the MOT in March, safe to drive, with no leaks & reasonably reliable - as far as almost 50 yrs old car can be reliable, that is :-D

Plan is to lift the body, have remaining body mounts replaced, change the lines, touch up the frame as it'll be exposed etc., but that'll take me lot of time and I'm not making it this winter - If I want to drive it this spring :-)

 

Interesting answer. My car is 2 years younger. My number 1's, both of them looked far worse when I actually removed them.
Less than a year ago.
Numbers 2 and 3. Out of the elements. Where in much better condition. But none the less squashed from years of service.
I did all 8 in a tiny one car garage. Lifting one side at a time. Doing it 1 - 2 hours at a time.
As I work 6 days a week and also have life duties beyond my Corvette. Chipping away 1 to 2 hours Max most evenings and some time on my one day off a week.
It was completed in under a month. It included fibreglass work at the number 4's and some frame welding.
So, doing new number 4's without the other 6. Still sounds like doing a half **** job.
Your car.
However, those other 6 will be compressed from years of service.
getting all your shimming correct with just 2 new mounts should be interesting.

 

Well, managing 4 vettes means you've got quite the skill set already! :-)

However, as far as my Vette is concerned - I'm doing everything for the first time and learning as I go. Also, with my car sitting in the garage most of it's time - it's never been driven in the US, exported into Germany straight away in '75 and served only for occasional drives, last 12 years, it's been driven only to the shop to have the fluids changed. Lots of bolts, nuts, etc - no one has touched it in all that time, so loosening something is hell a lot of times. I mean, maybe it's an easy job for you because you've already spent a bunch of time on your 4 Vettes and maybe you've done this particular job before. I know, there are videos on YT, it's great, but - how many times do you actually get it as nice&easy on your car as it's done on YT? :-D

Often I get into a situation where I have to do whatever it takes to save the bolt/nut/etc in question (if it's not severely weakened), because here I simply can't go to the hardware store around the corner and buy a new one in the grade I need. For example, I'm currently trying to do a no-damage extraction of the bolt that holds the rear shock on top (stuck in the metal housing inside bushing). In the US I would simply cut it and buy a new one, but here I just can't get that bolt anywhere. And I don't want to get into any shenanigans like re-drilling the rear shock housing on the M12 metric bolt etc... These can be ordered from the US, of course, but it could get really expensive ordering those small parts separately, so I'm consolidating these - but again, it takes time and I like to have things done and not to have rear of the car in boxed in a garage for months because I'm waiting for 3 bolts :-)

I try to follow a methodical approach - disassemble, repair, replace, finish, move on to the next section of the car. I know a few people who got a classic car, took it apart in the garage, and then never put it back together. :-D And for me, in this moment - lifting the body & do all that is necessary, it's a big project that I can't plan together with everything else I have planned for this winter.

And unfortunately, this is something to be taken into account for planning and in terms of goal setting...

Just to make myself clear, I do really appreciate your response and this is just an explanation of how things are, not an counterattack (as there has not been any attack in the first place), nor excuse.

 

No, there is no spacer between the fiberglass and the steel reinforcement. You rivet the reinforcement directly to the fiberglass. If there was a spacer in there then someone has been playing in the #4 area already.
David Howard
AllC34Me

 

If you call Mike at Bair's he will be glad to review this with you to assure you that you are getting all of the parts you need for this replacement. Good luck.
David Howard
AllC34Me

 

Mr. Vat887,
you have me all wrong.
I am in Australia. Land of metric bolts.
I too never lifted my body, (one side at a time).
I truly believe that YouTube videos are made by people that know how to make videos. NOT how to fix cars. Won't waste my time on YouTube.
just saying, there is a right way to do this job.
If it's worth fixing, it's worth fixing right! If it's not worth fixing right. ........
Well then maybe it's not worth fixing.

 

AllC34Me:
Thanks, I'll either email them or give them a call. I'm still waiting on the order because I haven't finished the suspension yet. There might be some additional fasteners or similar parts that could break in the process, and I might need replacements...

4-vettes:
No problem

I thought that Australia also uses inches, miles, pounds, and all kinds of other weird stuff too:-) I've never been there yet, though I've been only approximately 5,000 to 6,000 kilometers closest so far, from both sides (Islands of Maupiti to the east and Rodriguez to the west). I'd like to visit someday, but planning is tough with that country being so huge :-)

You're right, I never questioned what you said, but, it is what it is. Of course, I'd rather replace all the body mounts at once. I'll leave it until last this year and if there is time and I can get all the other repairs done before the deadline, I'll try to do it the right way.