Does anyone know the size of the rear shock absorber mount bracket bolts?

Maintenance/Repairs
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1

Hello,

I need to replace the rear shocks on my 2010 but I have no real hope of removing the bolts that go through the top and bottom of the shocks. These are rusted far beyond removal. I have tried PB blaster and a torch on the lower bolts with absolutely no success. I don’t think it’s safe to use a torch on the upper bolt. I can cut off the lower bolt but there isn’t enough space to access the upper bolt with a saw or grinder.

I think it will be best to remove the bracket the that upper shock bolt mounts to. I don’t know if I can get the bolts out without breaking them so I don’t want to try to remove one to see what it is. I want to have the replacement hardware ready when I try the repair. Even if I can get the bolts out in one piece I would still replace all of them with corrosion resistant coated bolts.

This is the bracket,

Mopar 4721664AB Passenger Side (RH) Shock Mount Bracket

which is located here,

Number 8 in the parts diagram

The mounting bolts are not listed in the parts diagram, which is very frustrating. I would never change out a bracket like this without using new mounting bolts. Why sell the brcket but not the fasteners?

Based on the size of the hex heads I suspect they are M8 (something like M8-1.25mm x 30mm) and would be class 10.9 with course thread. It may be a flange bolt or a hex bolt with an integrated washer. I have no idea how long the bolts. The bolts that mount the shock into the bracket are M10 and these look a bit smaller.

If anyone knows what these are I would appreciate the information.

LMHmedchem

2

M8 for the lower mount seems too small.

Why not cut the old ones out and head over to your local hardware store with the measurements?

Since you don’t know the length, why do you need the diameter?

1 Like
3

Thanks for the reply.

M8 for the lower mount seems too small.

The bolts that go through the top and bottom of the shock absorber are M10-1.25x70mm grade 10.9 flange bolts, at least that is what the replacement parts I have are. I will check again before I try cutting off the lower bolts. It can be a little hard to measure when they are so rusted but I will clean off the end of a bolt with PB blaster and a wire brush wheel.

Why not cut the old ones out and head over to your local hardware store with the measurements?

I have the brake lines off of my explorer while I am painting the frame so this is currently the only working vehicle I have. I would probably be fine to drive with 3 of he 4 mount bolts in place but I would rather not. Also, the hardware store isn’t guaranteed to have what I want. They would have grade 10.9 M10 bolts (probably) but may not have the right length or the anti-corrosion plating I want. They would also cost about 10 times as much. That’s not a deal-breaker for 8 bolts but I would rather order exactly what I need for a better price.

Since you don’t know the length, why do you need the diameter?

I need to know everything, the diameter, thread pitch (since these are threaded into the frame and not a nut), and the length (though generally there is some wiggle room on the length).

It seems I should be able to find out the specs of the bolt without having to take one out, but who knows.

LMHmedchem

4

I never had a problem getting mine off but I did have to buy the correct socket. Maybe 15 mm don’t remember but Gm. A little pb blather ahead of time and an impact wrench or some leverage should do it. But I have a rule to never start a project on one car until I’m done with the other.

1 Like
5

No friends? Or a bicycle?

Never a good idea to disable both cars at the same time.

6

I had to remove some really rusted bolts a couple weeks ago. The washer was part of the bolt, which provided more surface to rust, & ever harder to remove. It was rusted fast & unlikely to ever rotate again. The bolts screwed into a captured (welded on) nut. I used a Dremmel tool w/cut off wheel to cut off the part of the bolt sticking out of the nut, then cut an “X” in the end of the bolt to center the drill, then drilled through the nut to remove the bolt. Maybe a Dremmel tool w/cut-off wheel will fit in the space, while a typical angle grinder won’t. Sometimes you can just cut off the nut, don’t have to mess w/the bolt other than hammer it out with a punch.

I expect you’ll have to wait on purchasing the replacement fasteners until after you’ve removed the bolts. Then you can take what you’ve removed to the hardware store to exact match some replacements. Make sure to match the grade, 10.9 or marks stamped on the bolt head, etc. Big job & frustrating, but diy’er doable.

7

There are bolts in the parts list that are not shown in the diagram. These bolts are the same size, old number/new number:

image
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The shock mount bolts are 12 mm. Note: the upper bolt threads into the body, replacing the bracket won’t help.

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8

So, if you do not think you can get the bolts out without breaking them off, what are your plans if and when you find the replacements. Do you have the tools and the skills to remove the broken bolts? If the bolts are so rusted in, do you have the extractor tools bits capable of removing the frozen bolts? Cheap Extractors will break off too…

9

When you say torch, are you talking a propane torch?

Or a blue wrench?

image

Tester

2 Likes
10

Looking at a video, this is a standard rear shock replacement with two bolts. Don’t make it more complicated. Of course there is rust so use some solvent on the nuts and threads ahead of time. Need a good ratchet or impact or both, plus a curved box wrench. The problem this is Chrysler with the nuts on the wrong side so access is harder. Don’t over think it but get the right tools.

1 Like
11

Worst case, go to a pull a part salvage yard and take one of there vans apart and measure everything you need… Or just to be safe, buy what you need and take it home to match up and or have a back up since you will be without a vehicle…

1 Like
12

The blue wrench not only solves automotive problems, it’s an electrician’s best friend too. A friend used to work on an electrical construction crew in a steel mill. He said they used to torch more than any other tool. Need a hole? Burn one. Is that bracket in the way? Burn it.

13

I watched a vdo too, just curious. For the rear shocks, the bolt head definitely seems to have the easiest access, compared to access to the nut. But if the bolt was oriented the other way, so the nut had easier access, I don’t see how that would make removing the bolt any easier? Either way, you still have to get a wrench/socket on both ends.

Or do you mean that if the nut was on the easier access side, it would be easier to knock the bolt out with a hammer once the nut was removed?

The bolt head seems to be resting on a separate washer. With that configuration, seems like rust penetrant, given a few days to work its magic, seems like it should be possible to twist the bolt head enough to wrench the nut off the bolt anyway. Removing the bolt from the mount probably still poses some difficulties.

It’s sort of interesting Car-Talk-wise, that if a diy’er is faced with this sort of problem and needs to solve it quickly in order to drive to work the next day, it can really be an unpleasant experience. But if there’s nothing time critical involved, it becomes a sort of puzzle and can be quite fun to try to figure out the easiest way to do it. A few years ago I found a very rusted pipe fitting to experiment with, decided to try everything possible to separate the two threaded together fittings, heat, various rust penetrant, various wrenches, big, very big. Even though I had perfect access, and plenty of time, I could never separate the two fittings. I didn’t have the blue torch though. I did try a map/oxy torch.

I’ve always been puzzled by that too. But bolt dimensions & strength rating are seldom published, even in the factory repair manual. The best manual I found for this sort of thing was for my old VW Rabbit, manual titled “How to Keep Your Rabbit Alive”. The author provided the wrench size you needed for each bolt in the procedure, a pleasant convenience for a diy’er.

I hope OP comes back and tells us how he solved this stuck fastener problem :slight_smile:

14

IIRC I bought a new bolt from the Chrysler dealer, special order, for maybe $11 - after looking at hardware and auto and fastener stores without success. And IIRC the nut is actually part of the welded-on bracket.

Addendum: this was on my 2007 T and C van.

15

One of the first diy’er jobs I did as part of taking a night school auto shop class was to replace my truck’s shocks. I lay on my back on the shop floor, wrenched and wrenched for close to an hour, could never get even one fastener to budge. Finally instructor comes by, asks me how I’m doing? I show him the problem, he gets out the shop’s blue torch, has the fasteners removed (cut out) in about 3 minutes … lol …

16

Factory manuals often have the specs for bolts in them. True one way or the other access is limited. It seems like more force would be required to turn the bolt than just the nut and getting the bolt out might be why they did it this way. Happily I haven’t worked on many Chrysler cars.

17

Sorry for the long delay. Crazy weather has caused some delays here. I will respond to these suggestions, hopefully later today.

LMHmedchem