C4 Rear Shock Mounting Studs
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C4 Rear Shock Mounting Studs
I have an 89, and the studs holding the top of the passengers sied shock at tge top have borken off inside the frame. I can feel the end of each of the 2 studs through the hole for the top of the shock, whereit goes through the frame.
Looking for tips on best way to fix.
Thoughts are to drill out the studs and replace with bolts, and use nuts and lock washers or nut with built in lockwasheer,
Is there a better way?
Should I use a drill that matches the size of the hole in the frame or start small and step up.
What grade of bolt?
Any suggestions well appreciated.
Thannks,
Harry G
Looking for tips on best way to fix.
Thoughts are to drill out the studs and replace with bolts, and use nuts and lock washers or nut with built in lockwasheer,
Is there a better way?
Should I use a drill that matches the size of the hole in the frame or start small and step up.
What grade of bolt?
Any suggestions well appreciated.
Thannks,
Harry G
Le Mans Master
Joined: Aug 2000
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From: Australia
Plate covers hole so you have no access to inside of rail
I would try to drill/ break the broken bolts out using progressively bigger drill bits so you keep the stock nut welded inside the rail
Last edited by rodj; Oct 24, 2010 at 09:13 AM.
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Thank you, had not throught about holding the other end. If I go progressively larger, do you think it would be possible once I got large enough to use a self tapping screw to turn the remaining treads throught he welded nut, that way would also have a sample size of bolt that would fit the nut?
Team Owner
Joined: Dec 1999
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From: Lacey WA RVN 68-69
NCM Sinkhole Donor
The OEM weld nuts don't have a lot of weld area to keep them in place. Chances are that only the corners of the nuts are welded to the frame. The force of drilling out the remainder of the bolt and trying to re-thread the nut could easily break the welds.
What caused the bolts to break? Rusted in place? If that was the case, the chances are that the rest of the bolt in the nut is also rusted. You could try soaking the area with something like PB Blaster for a couple days and try to use an Easy-Out to remove the broken piece.
The original shock mount nut doesn't take a whole lot of torque, something like 22 ft-lbs. If you do get the broken part out, take a bolts from the driver's side upper rear mounting bracket and use that to get more bolts. They are a metric size and probably a grade 8.8.
What caused the bolts to break? Rusted in place? If that was the case, the chances are that the rest of the bolt in the nut is also rusted. You could try soaking the area with something like PB Blaster for a couple days and try to use an Easy-Out to remove the broken piece.
The original shock mount nut doesn't take a whole lot of torque, something like 22 ft-lbs. If you do get the broken part out, take a bolts from the driver's side upper rear mounting bracket and use that to get more bolts. They are a metric size and probably a grade 8.8.
Le Mans Master
Joined: Sep 2006
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From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
Just a couple thoughts here.
1. Those aren't studs, they are bolts. go look at the other side. You can soak the broken bolts with rust dissolver like previously mentioned. drill into the bolts, and use an e-z out to remove them and install new ones using the original frame captive nuts.
1. Those aren't studs, they are bolts. go look at the other side. You can soak the broken bolts with rust dissolver like previously mentioned. drill into the bolts, and use an e-z out to remove them and install new ones using the original frame captive nuts.
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Thanks, I am able to get my index finger through the hole for the top of the shock and can feel the pointed end of the bolt. Sprayed them with BP Blaster, I guess I will have to wait for them to penetrate. One is a straight shot with a drill, the other has the split shaft in the way. I either need to angle with a small bit and try the easy out or get a right angle adapter on the drill. Keeping it in the center will be the challenge.
I do have the driver side off the ground so I can support the lower end of the shock and remove one of the bolts and try and find a similar one. (or is it better to remove the shock entirely?) I replaced the shocks about 3 years ago and they may have been overtorqued. Will loosen and retorque the ones on the driverside to spec, probably buy 4 new bolts and replace the driverside too.
Thanks again
I do have the driver side off the ground so I can support the lower end of the shock and remove one of the bolts and try and find a similar one. (or is it better to remove the shock entirely?) I replaced the shocks about 3 years ago and they may have been overtorqued. Will loosen and retorque the ones on the driverside to spec, probably buy 4 new bolts and replace the driverside too.
Thanks again
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Well, I got one bolt out of the driverside and decided to take them both out, ont a good idea, broke it off removing it, got it half was out and it snapped. Nuts appear to be locking nuts as the drag on the nut as you remove the bolt remains heavy. I used the PB on the one I took out and in the hole and tried to reinstall, constant drag, will need to clean more to reinstall and must be a lock nut. Look like I now have 3 to remove.
Can anyone confirm it is a locking nut and any hints on getting them out, I guess I need to spray some more BP Blaster on them and let it soak for a couple of days.
How bad is it to dirve local without the shocks?
Can anyone confirm it is a locking nut and any hints on getting them out, I guess I need to spray some more BP Blaster on them and let it soak for a couple of days.
How bad is it to dirve local without the shocks?
Team Owner
Joined: Dec 1999
Posts: 34,873
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From: Lacey WA RVN 68-69
NCM Sinkhole Donor
Bad. Very bad. 
Not only does the shock absorb the bouncing from the wheel, it also keeps the spring from moving too far. While there is a bump stop, the spring will be moving through a much longer sweep and at a faster rate.
And if you should ever have to perform some sort of avoidance maneuver in traffic, you could easily lose control.
Not only does the shock absorb the bouncing from the wheel, it also keeps the spring from moving too far. While there is a bump stop, the spring will be moving through a much longer sweep and at a faster rate. And if you should ever have to perform some sort of avoidance maneuver in traffic, you could easily lose control.
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Brett Foote
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From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
When removing bolts that are frozen, after getting them to just barely turn, tighten them again, and turn back, tighten, turn back, keep this up till you have them out. yes, it's tedious, but it's the only way.
Le Mans Master
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From: Life is just one big track event. Everything before and after is prep and warm-up and cool-down laps
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St. Jude Donor '12
On my 92 I got one of the bolts cross threaded and broke off inside the weld nut.
Just drilled out the old bolt that was stuck, cleaned out the threads and used a new bolt.
Worked like a champ and 10 track days later still tight and holding strong.
Just drilled out the old bolt that was stuck, cleaned out the threads and used a new bolt.
Worked like a champ and 10 track days later still tight and holding strong.
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OK, the plot has thickened.
Started working the driver's side to remove the broken bolt. Was able to drill with a number of increassing sizes. Heated the bolt and applied PB Blaster to try and get it sucked up the threads. Installed a #4 easy out and broke it off in the bolt. After trying multiple methods to remove the easy out, used a punch, 3# hammer and knocked the nut off the back of the frame, leaving just the hole.
Still working on the other 2 bolts on the passengers side. Got 4 dtill sizes on the easy bolt (not over the axle) and broke the 5th size, think I can get it out with vise griip, if I am careful (cobalt drill).
For the one without a nut, has anyone have suggestions? have thought about a screw stud with an allentip, that I could hold the stud while I tightened it. Also JB weld a new nut, but concerned about getting it clean enough to holdm, not sure it would.
Any ideas are welcome.
Thanks
Started working the driver's side to remove the broken bolt. Was able to drill with a number of increassing sizes. Heated the bolt and applied PB Blaster to try and get it sucked up the threads. Installed a #4 easy out and broke it off in the bolt. After trying multiple methods to remove the easy out, used a punch, 3# hammer and knocked the nut off the back of the frame, leaving just the hole.
Still working on the other 2 bolts on the passengers side. Got 4 dtill sizes on the easy bolt (not over the axle) and broke the 5th size, think I can get it out with vise griip, if I am careful (cobalt drill).
For the one without a nut, has anyone have suggestions? have thought about a screw stud with an allentip, that I could hold the stud while I tightened it. Also JB weld a new nut, but concerned about getting it clean enough to holdm, not sure it would.
Any ideas are welcome.
Thanks
Le Mans Master
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From: Life is just one big track event. Everything before and after is prep and warm-up and cool-down laps
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St. Jude Donor '12
Nope, JB weld is not going to be enough.
You'll have to at least tack weld a new nut on there. good luck with that. You may be able to cut a hole in the floor over the area big enough to weld the nut on.
Another option is to cut a slot in the frame wide enough for the proper size wrench to go in there and hold the nut. Take a look at some of the pictures folks have posted moving the stock mounts to install coil over shocks.
You'll have to at least tack weld a new nut on there. good luck with that. You may be able to cut a hole in the floor over the area big enough to weld the nut on.
Another option is to cut a slot in the frame wide enough for the proper size wrench to go in there and hold the nut. Take a look at some of the pictures folks have posted moving the stock mounts to install coil over shocks.
