SOS. Need help with lower control arm.

[Sw00per]

SOS. Need help with lower control arm. As you see in the photo the lower control arm needs to move forward. The bolt came out easy... now to get it back. I did try to jack up the rear a bit but that did not seem to work. Help!

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[Bandit’s Lair]

Do you have the other side in? Is the control arm at exactly the correct length? Can you jack up the axle on 1 side with a jack on wheels and try to shimmy it back a bit? My head is telling me if the arms aren’t set correct and it’s falling short. Something isnt lined up correctly. Go back through and measure everything out again. Better safe than sorry.

 

[kevman65]

Try the floor jack on the side of the axle you're working. Raise and lower the jack to see where it gets you closer.

Ratchet strap on that side of axle back to frame to draw it in.

 

[Sw00per]

Do you have the other side in? Is the control arm at exactly the correct length? Can you jack up the axle on 1 side with a jack on wheels and try to shimmy it back a bit? My head is telling me if the arms aren’t set correct and it’s falling short. Something isnt lined up correctly. Go back through and measure everything out again. Better safe than sorry.

Yes the other side is in. I am attempting to install the MC skid plate for the LCA bracket. So the length was set before so that was good. The bolt came out easy but now does not align. I attempted to jack it up from the rear diff and from the axel on the side to move forward without luck. I have also tried a ratchet strap and it helps a bit.

The jeep is on a slight decline toward the rear would that cause it?

 

[Sw00per]

Try the floor jack on the side of the axle you're working. Raise and lower the jack to see where it gets you closer.

Ratchet strap on that side of axle back to frame to draw it in.

Trying that and is maybe a 1/4 inch off.

 

[Bandit’s Lair]

Yes the other side is in. I am attempting to install the MC skid plate for the LCA bracket. So the length was set before so that was good. The bolt came out easy but now does not align. I attempted to jack it up from the rear diff and from the axel on the side to move forward without luck. I have also tried a ratchet strap and it helps a bit.

The jeep is on a slight decline toward the rear would that cause it?

Incline or difference side to side could have an effect. If you know the arms are correct throw another ratchet strap or a stronger ratchet strap on it. Axle needs to move to the arm. Maybe a long pry bar and a second set of hands if it’s only a 1/4”.

 

[Gizmo]

Put a jack under the pinion side of the diff and raise it and the control arm WILL move as the pinion rotates up. Their is a flat section i usually just put a bottle jack under it. The springs rotate the pinion down so ya need a jack to rotate it up.once you have tension on the diff with the jack you can take both lower arms off. Use the jack to set your caster and adjust your arms to the mounting holes. I have also just put my foot on the tire and roll it forward or back wards slightly depending on which ya need to go. This is easy to fix no need for ratchet straps. Dont over think it

 

[BlueScapegoat]

Put a jack under the pinion side of the diff and raise it and the control arm WILL move as the pinion rotates up. Their is a flat section i usually just put a bottle jack under it. The springs rotate the pinion down so ya need a jack to rotate it up.once you have tension on the diff with the jack you can take both lower arms off. Use the jack to set your caster and adjust your arms to the mounting holes. I have also just put my foot on the tire and roll it forward slightly. This is easy to fix

This guy has it. Jack the pinion end of the diff, just try not to jack on the pinion flange itself (although it would probably be fine)

 

[Gizmo]

I have simply pushed the tire backwards and with my foot just slid a piece of wood as a tire chock to hold the tire in place until the control arm and mounting hole lined up

 

[Sw00per]

Thanks for all the replies! Success - it took two ratchet straps and an extra set of hands\eyes to align the hole! Now I believe it is the torque is 111 + 65 degrees. Please correct me if I am wrong.

 

[Jteakus]

Ratchet strap and line up tool were gonna be my suggestions.

 

[BlueScapegoat]

Thanks for all the replies! Success - it took two ratchet straps and an extra set of hands\eyes to align the hole! Now I believe it is the torque is 111 + 65 degrees. Please correct me if I am wrong.

In my experience it's always been whatever torque spec is in the FSM then torque it again halfway down the trail to as tight as you can get it when the factory torque spec was inevitably not enough.

Depending on the type of mount and bushing I've literally just starting to look up the torque specs on the bolts themselves.

Not that I recommend that behavior, of course.

 

[Pliny]

Now I believe it is the torque is 111 + 65 degrees. Please correct me if I am wrong.

Are those the stock bolts? If they are aftermarket / longer, the "+so many degrees" is only for the thread pitch of the OE bolts. The OE LCA to frame are M16x1.5 Fine. FWIW the instructions for the Mopar 2" lift that I have says torque them to 185 ft lbs.

If the bolts you are using are coarse thread then +65 degrees is going to end up with a higher torque than on a fine thread bolt.

 

[Sw00per]

Are those the stock bolts? If they are aftermarket / longer, the "+so many degrees" is only for the thread pitch of the OE bolts. The OE LCA to frame are M16x1.5 Fine. FWIW the instructions for the Mopar 2" lift that I have says torque them to 185 ft lbs.

If the bolts you are using are coarse thread then +65 degrees is going to end up with a higher torque than on a fine thread bolt.

They are after market Metalcloak supplied 5/8 bolts. They appear to be the same thread pitch as the factory bolt.

 

[Pliny]

They are after market Metalcloak supplied 5/8 bolts. They appear to be the same thread pitch as the factory bolt.

If they appear similar to OE, then they are probably UNF 5/8 - 18 which has 18 threads per inch.

The OE bolts have thread pitch of 1.5 mm, so 25.4 / 1.5 = 16.9333..... threads per inch.

There are reasons that I didn't end up in a mechanical engineering / material science career but 65/360 x 1/18 = ~0.010031 inches of additional compression / bolt stretch. Whereas 65/360 x 1/16.933 = ~0.010663 in. (25.4 / 1.5) / 18 = ~0.94074. So ~6% less.

I suspect the actual clamping force delivered to the assembly is a function of the actual material the bolt is made from, as well as the difference(s) between metric class 10.9 and SAE grade 8.

I learned this lesson when I initially went to install the LCA skids on my JTR. The longer aftermarket bolts that came with the skids were coarse thread, and trying to use the +degrees spec resulted in them being drastically overtightened.

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