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Thread: Cobra accident averted (check your suspensions!)

  1. #1
    Senior Member Funding Member RedBarchetta's Avatar
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    Cobra accident averted (check your suspensions!)

    About a month ago I noticed the right half-shaft inner boot started flinging a fair amount of grease. A quick inspection revealed no torn boots but the clamp was loose. I tried to lightly hammer it a little tighter, but to no avail it continued to throw more grease with each drive. Rather than try to perform an in-car grease repack and applying a new stainless band (really no room to do an adequate job), I had to pull the entire half-shaft. Because I don’t have the right socket to remove the outer cap nut, I just decided to pull the hub carrier with it (having done the exact repair about 13-14 years ago).

    Imagine my shock when I pulled the tire/rim and saw this:



    Holy smokes! If not for the safety wire, I would have lost one of the lower control arm bushing bolts and no doubt a bad moment would have occurred immediately thereafter. Not content with just having the right side fixed, I gave the left side the same scrutiny. The same front bolt on the lower control arm didn’t appear loose, but it took no effort for me to untighten it once the safety wire was removed.

    So I had TWO starting to let go, one on each side.

    I’m getting both completely rebuilt and greased with new boots, clamps and cap nuts for $130. Found a shop in Daytona that does nothing but CV’s and transmission/differential work.

    As to how two cap bolts worked their way loose, I have a theory but it pertains to some work that the interim owner had done to the back half of the car prior to my buying it back. As part of my R&R, all bolts and threaded recesses will be completely degreased and chased with taps, and a fresh tube of blue Locktite (also acts as an anti-seize) will be applied. And thicker safety wire than was on there prior.

    I’m also going to perform a very thorough once-over on every fastener, front to back. I feel like I dodged a significant bullet here.
    Last edited by RedBarchetta; 08-06-2019 at 01:03 PM.
    -Dean

    "...tires spitting gravel, I commit my weekly crime."

  2. #2
    Administrator Funding Member Ron77's Avatar
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    Dean,

    Well I am glad that you found this before it completely fell apart when you were driving it. I always go over mine after each drive and check bolts and look for any wear or anything that may be showing up.

    Ron


    MY ALBUMS

  3. #3
    What's a loose bolt among friends?
    Never a dull moment with these cars.

  4. #4
    Senior Member Funding Member Morris's Avatar
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    Dean...

    Now you know why racers pull the wheels after every session on the track.......we use to have a routine when the car came off the track....pull the wheels, retorque the halfshafts both inner an outer, make any adjustments to camber & spring rates, check the alternator, check the d-shaft, sway bar, and bleed the brakes after they cooled down....

    Ahhhh to be young again....we use to throw our bodies down under the car....how crazy and passionate can you be.....

  5. #5
    Senior Member Funding Member RedBarchetta's Avatar
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    I'm not going to make any excuses...I should have seen this earlier (unless it just happened on my last drive). My drive-on ramp system enables me to crawl under after every outing. Clearly I need to get back into that habit (age be damned).

    I tell others that I only drive as fast as my guardian angels can fly. Apparently, one of them was also reaching down and keeping that one bolt just snug enough. Picked up the refreshed half-shafts and they look like brand new. Now onto the assembly and it should be back on the road in a couple days.
    -Dean

    "...tires spitting gravel, I commit my weekly crime."

  6. #6
    GROUCHY FUC***G OLD APE Funding Member Silverback's Avatar
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    I did not check my car after every drive, but I don't think it ever went more than 3 drives. I also marked all the bolts I could reach with paint so I could do a quick visual check to make sure the marks still lined up.

    Glad to see you caught this early Dean. I'm also assuming you have replaced the rear top shock mounts on yours. If not, you need to. Also the original AVO shocks were a weak point.

  7. #7
    Senior Member Funding Member RedBarchetta's Avatar
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    I replaced the upper shock mounts with one of the first sets that RT (Cobra Valley) produced. All suspension bolts are paint striped EXCEPT the four lower control arms that are safety wired. Going to add paint stripes to those, too.

    I ditched the AVO shocks a long time ago and now run double-adjustable QA1’s. The car also has RT’s Heim-joint adjustable anti-roll bars and this combination of shock/anti-rollbar really plants the ride.

    Just ordered this morning new lower rear control arm bushings from Hillbank and hopefully I can start buttoning it all back together in a week. Both axles were repacked and banded, and I also used taps on all bolts and bolt holes to ensure a clean assembly.
    -Dean

    "...tires spitting gravel, I commit my weekly crime."

  8. #8
    Senior Member Funding Member RedBarchetta's Avatar
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    UPDATE:

    So this is where we left off almost a week ago. Both reconditioned axles out (still attached to uprights) and the bottom rear of the car torn apart:



    Now more hurdles! The lower rear control arm Delrin bushings from Hillbank have an ID 0.03" larger than mine. The change occurred when the factory went from a steel upright to an aluminum one. So even the steel rods that go inside also have a larger ID (fatter bolts). Since the larger bolts won't work with my older steel uprights, these bushings are of no help. Hillbank is a great group of guys, but even they can't get the factory to make any more of these older varieties.

    Here's a photo of a bad Delrin bushing and one that is still intact:



    What's interesting is that the two really bad Delrin bushings were on the opposite side (driver's) of where I discovered the loose bolt. Driver's side control arm on left, Passenger side on right:



    So the Passenger side bushings all look solid and most likely had nothing to do with the bolt loosening. So Hillbank mentioned that any competent machine shop can mill some new Delrin bushings using one of my good ones. I then called Dennis Olthoff at Olthoff Racing (a renowned Superformance dealer, installer and repair shop in North Carolina) and he said the same thing. He has ONE left, which he purposely kept just in case he needed to have some made. Well, my call has prompted him to check with his machine shop on Monday to determine if that is possible. {fingers crossed}

    So right now I'm working two options, Olthoff first and then Hillbank next. Is it common practice for a competent machine shop to be asked to machine solid rods of Delrin into bushings? I'm just naive on this part of these cars and assumed that my typical Superformance resources would have a small parts bin with half dozen laying in there. My goal is to purchase four (two for the driver's side and two to have as spares). I have not explored local machine shops yet, choosing to default to two known parts/repair facilities that have dealt with dozens of these occurrences.

    So basically the car is still shelved because of a couple $12 bushings. Have used the spare time to machine sand (starting with 400 all the way up to 1000 grit) and micro-polish the steel rods that go inside the bushings, and they should turn more freely once it's all stitched together again (note the holes for zerk grease fittings at each outer rod).
    Last edited by RedBarchetta; Today at 10:05 AM.
    -Dean

    "...tires spitting gravel, I commit my weekly crime."

  9. #9
    GROUCHY FUC***G OLD APE Funding Member Silverback's Avatar
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    Have you thought of going with bronze bushings instead of Delrin?

    For my sway bars I bought some bronze bushings from McMaster-Carr and then machined them on my mill to what I needed.

    https://www.mcmaster.com/bronze

  10. #10
    Senior Member Funding Member Morris's Avatar
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    Quote Originally Posted by Silverback View Post
    Have you thought of going with bronze bushings instead of Delrin?

    For my sway bars I bought some bronze bushings from McMaster-Carr and then machined them on my mill to what I needed.

    https://www.mcmaster.com/bronze
    Silvers right on Mark.... and Bronze is what is in the original bushings ...McMaster Carr has it all....

    Take your control arms and the thru bolt to a machine shop and they will do it easily...

  11. #11
    Senior Member Shootnride's Avatar
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    Quote Originally Posted by RedBarchetta View Post
    UPDATE:Is it common practice for a competent machine shop to be asked to machine solid rods of Delrin into bushings
    Yes, it's very common. If I had the Delrin (which is pretty easy to get) and the dimensions, I'd just make them for you. Do you have the dimensions ?

    Ted
    Some people raise the IQ in the room when they enter.......others when they leave

  12. #12
    Senior Member Funding Member RedBarchetta's Avatar
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    Quote Originally Posted by Shootnride View Post
    Yes, it's very common. If I had the Delrin (which is pretty easy to get) and the dimensions, I'd just make them for you. Do you have the dimensions ?

    Ted
    Yes, Ted, I have a digital caliper so here are the dimensions. WOW, I really appreciate the offer but let's see what the first source (Olthoff) comes back with first. In the meantime, maybe you can check local availability of Delrin stock based on these dimensions. Apologies for the sideways pics...they didn't auto-correct when I uploaded.

    Length .720


    OD = .945


    OD with flange = 1.180


    ID = .790


    flange thickness = .093 was the most consistent dimension that I could get (was tough to get caliper to stay flush while photographing with the other hand). I then checked a few others and came up with .094.
    Last edited by RedBarchetta; Today at 12:33 PM.
    -Dean

    "...tires spitting gravel, I commit my weekly crime."

  13. #13
    Senior Member Funding Member RedBarchetta's Avatar
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    Quote Originally Posted by Morris View Post
    Silvers right on Mark.... and Bronze is what is in the original bushings ...McMaster Carr has it all....

    Take your control arms and the thru bolt to a machine shop and they will do it easily...
    Thank you, Morris. I was hoping you would see this and respond. As I mentioned to Ted previously, I'm going to give Dennis an opportunity on Monday to get me an answer. Then I either go local or hire Ted (keep the money in the family).
    -Dean

    "...tires spitting gravel, I commit my weekly crime."

  14. #14
    Senior Member Funding Member Morris's Avatar
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    Quote Originally Posted by RedBarchetta View Post
    Thank you, Morris. I was hoping you would see this and respond. As I mentioned to Ted previously, I'm going to give Dennis an opportunity on Monday to get me an answer. Then I either go local or hire Ted (keep the money in the family).
    Good deal....����

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