Author Topic: Brake caliper bolt tightening on a 1967 Eldorado?  (Read 328 times)

Offline 67_Eldo

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Brake caliper bolt tightening on a 1967 Eldorado?
« on: June 10, 2017, 05:14:01 PM »
Yesterday I was 200 miles from home when I backed into a parking space, causing my loose left-front brake caliper to slice the valve stem from the inside of the left-front tire. This was unusual so I've attached pics of the damage.

The caliper's top bolt had worked itself loose and fallen out. If I rolled forward, the caliper "clicked" against the valve stem. But if I backed up, the caliper turned into a valve-stem-ripping monster.

Amazingly, I found the bolt a few hours later and got it back into place using an old crescent wrench (the only wrench I was carrying that would fit). Needless to say, I had no idea if the bolt was tight enough or not.

Since the sliced-off valve stem and the loose caliper bolt had apparently rattled around inside the wheel for a few rotations, the CV boot was shredded. With a questionably tight caliper bolt and an exposed CV joint, the 200-mile drive home (at night) was something of a nail biter. BTW, the spare I put on looks to be about 20 years old. I was sort of amazed when I arrived home without incident.

What is your advice on caliper bolts? The shop manual has torque numbers, but do those still apply to older "stretched" bolts? It also seems that some Loctite might be a very good thing. Should I crank the caliper bolts down a bit more tightly using Loctite?


Offline TJ Hopland

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Re: Brake caliper bolt tightening on a 1967 Eldorado?
« Reply #1 on: June 10, 2017, 06:15:20 PM »
Got a picture of what this bolt and caliper looks like?    I don't think there are many people here including me that are familiar with that early fixed caliper design.
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
75 Eldo rusty but trusty
80 Eldo Diesel
And other assorted stuff I keep buying for some reason

Offline 67_Eldo

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Re: Brake caliper bolt tightening on a 1967 Eldorado?
« Reply #2 on: June 10, 2017, 06:42:36 PM »
This isn't a pic of my car -- I wasn't in a picture-taking mood -- but this is a 67 caliper from Gerald's great site (http://www.eldorado-seville.com/mycars/67eldo/).

Offline The Tassie Devil(le)

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Re: Brake caliper bolt tightening on a 1967 Eldorado?
« Reply #3 on: June 10, 2017, 06:54:05 PM »
You are a lucky fellow.

As for tightness, I just tighten these bolts to what I feel is sufficiently tight enough, then a tad more.

The secret is not to use a spanner that is too big, or small, and this comes with experience.   

But, in the case of a person that isn't sure, use the Manuals' torque specifications, as you cannot go wrong (but this is incorrect in the '72 Shop Manual for the cylinder head bolts) and no need for Loctite.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'55 Buick Special Post Coupe (LHD)
'74 Chris Craft Gull Wing RHH
(Past President Modified Chapter)

Offline 67_Eldo

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Re: Brake caliper bolt tightening on a 1967 Eldorado?
« Reply #4 on: June 12, 2017, 11:04:59 AM »
I didn't think so at the time but yes, I am a lucky fellow.

I just took these photos (Monday morning) of the brake caliper/CV boot condition. Needless to say, I haven't moved the car since I got home Friday night.

The top caliper bolt was still tight after the 200-mile journey. The bottom caliper bolt, however, had worked itself loose by about 1/4".

The CV boots aren't completely shredded but they aren't in good shape either. :-)

Offline The Tassie Devil(le)

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Re: Brake caliper bolt tightening on a 1967 Eldorado?
« Reply #5 on: June 12, 2017, 07:06:12 PM »
Until you get the chance to pull the axle and replace the boot, you can get one of those replacement boots that are split, and you bolt them together.

I did that in 2008 to my '72, and it lasted until I replaced it in 2010, after driving 6,000 miles.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'55 Buick Special Post Coupe (LHD)
'74 Chris Craft Gull Wing RHH
(Past President Modified Chapter)

Offline TJ Hopland

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Re: Brake caliper bolt tightening on a 1967 Eldorado?
« Reply #6 on: June 14, 2017, 09:36:10 AM »
Those are not original boots.   Those are some sort of repair boot.    Originals didn't have screws in them.   The screws are there to allow you to install the boot when its still in the car.   I never tried but read that the 88+ chev 4x4 boots kinda fit so I assume that is what those are.   I suppose its possible that those were an aftermarket item made for these cars back in the day?   Unless that was something unique to the 66/67 shafts?   I thought it was just the inner flange that was different on the early ones.

Its hard to tell in the pictures but it sort of looks like the whole CV shaft isn't parallel to the knuckle which would indicate a bearing issue.  Maybe its just the way the photos look.   I looked at all of em and they all look odd. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
75 Eldo rusty but trusty
80 Eldo Diesel
And other assorted stuff I keep buying for some reason

Offline 67_Eldo

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Re: Brake caliper bolt tightening on a 1967 Eldorado?
« Reply #7 on: June 14, 2017, 11:25:08 AM »
I talked to a local mechanic here (NOT one of the people who worked on it before) who drives a 1970 Eldorado and he suggested replacing the whole axle assembly. So that's scheduled for next week.

In the meantime I have some wiring and vacuum issues to work out.

One weird incident (which happened only once) is that when I turned the headlights on, the headlight covers came *up*, firmly and did not move no matter if I had the lights switched on or off. After it sat an hour or so, the normal headlight-cover operation resumed. This problem is not high on my to-do list, but it is another one I'm keeping in mind.

Thanks!

Offline 76eldo

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Re: Brake caliper bolt tightening on a 1967 Eldorado?
« Reply #8 on: June 15, 2017, 08:03:31 AM »
As Bruce said, it's a feel thing.  You don't want to overtighten it but it has to be on there tight.  I have done front brakes and rear disc brakes at least 100 times on my cars over the years and never had that issue.  If you use some threadlocker, use the blue, not the red.  Sorry for the damage...

With axles, I always replace the whole thing.  They are not very expensive and much less labor intense than cleaning out the old grease, checking the bearings, reloading new grease and fastening the boot.

Brian
Brian Rachlin
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I prefer email's not PM's   rachlin@comcast.net

1960 62 Series convert with factory Tri Power
1960 Eldorado Seville
1970 DeVille convert
1976 Eldorado convert
1980 Eldorado Hess & Eisrnhardt convert
1981 Eldorado Hess & Eisenhardt convert
1985 Eldorado Biarritz convertible
2007 DTS
2012 CTS Coupe
2017 CT5

Offline 67_Eldo

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Re: Brake caliper bolt tightening on a 1967 Eldorado?
« Reply #9 on: June 15, 2017, 09:50:55 AM »
Thanks!

I got the bolts cranked down to what feels tight to me. There's not much room to move a wrench around in there.

Since nobody (including the manual) recommends threadlocker, I didn't use any.

I'm still not going to drive it again until it is time to install the new axle. I want to get it up on a lift where I can see things more clearly.

Offline The Tassie Devil(le)

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Re: Brake caliper bolt tightening on a 1967 Eldorado?
« Reply #10 on: June 15, 2017, 07:25:43 PM »
With axles, I always replace the whole thing.  They are not very expensive and much less labor intense than cleaning out the old grease, checking the bearings, reloading new grease and fastening the boot.  Brian
I wish it was that easy.

In 2008 I tried to purchase a pair of axles so that I could ship them home in the container, and going to the local NAPA store where I was staying, they couldn't get me the correct replacements, no matter how many times they tried.   Each time, the replacement axles were the wrong length, and diameter, and I even had a pair of old ones for them to measure up.   Time came for the container to be closed up, and alas, no replacements had arrived.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'55 Buick Special Post Coupe (LHD)
'74 Chris Craft Gull Wing RHH
(Past President Modified Chapter)

Offline Glen

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Re: Brake caliper bolt tightening on a 1967 Eldorado?
« Reply #11 on: June 16, 2017, 03:28:51 AM »

With axles, I always replace the whole thing.  They are not very expensive and much less labor intense than cleaning out the old grease, checking the bearings, reloading new grease and fastening the boot.

I have a number of spare axels I removed from parts cars.  I usually overhaul them and have at least one ready to install.  I does take a little work but I avoid the possibility of getting china junk.    And someone mentioned that the threads for the axel nut may be different then original.   
I have even opened up the 67-68 only wheel bearings to clean and re-grease them. 
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Offline 67_Eldo

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Re: Brake caliper bolt tightening on a 1967 Eldorado?
« Reply #12 on: June 16, 2017, 04:15:14 PM »
I'll find out on Tuesday morning what the local Eldorado expert will use as far as his parts source. If he doesn't have a source already in mind, I'll check back here.

Thanks!