I got a "Bang" in the rear end

[Pedigry]

Hey guys,

I have a 70 mustang with a ride tech 4 link setup in the rear with their coilovers. It is the triangulated 4 link.

I am getting a "bang" when I down shift the car (C6 auto with a manual valve body and a gear vendors). Sometimes it sounds like it comes from the right side of the car and sometimes it sounds like it comes from the left (which is why it has led me to believe it's the lower 4 link bushings).

If it came from the center I would think third member or gear venders but it distinctly comes from either the left rear, or right rear or both sometimes. It almost sounds like the are bound and then they are coming unbound. The lower 4 link arms have no adjustment in them, I think they are older designs as the new ones usually have a heim joint on at least one end.

I have gone through a range of motion on the rear end, I can't get it to do it on the stands. It doesn't do it all the time, but it does do it most of the time. If i have the gear vendors engaged and I un-engage it, it will do it almost every time. When I manually drop a gear, it will do it as well, more so at higher rpm as it's more of a "jerk" to the rear end. I have adjusted the pinion angle form 1 to 3.5 and it made no difference.

There is nothing that is touching anywhere on the suspension. It's not rubbing anywhere, the coils are free through their range of motion. It's not hitting the bump stops. I can only think it's the lower trailing arm bushings but when I check them by hand they are tight. I will try and post some pics of the undercarraige.

Thanks in advance for any ideas you might have.201225

[Josh@Ridetech]

The only way the suspension would make a banging sort of noise is if the bushings had wore out like you mentioned or something has came loose and is now moving. You might not notice anything just by cycling the suspension, it may need more force (like the downshift) to get everything to shift and create that clunk. Have you pulled the four link bars down yet to look at them yet? That's the old style rubber bushing we used to use, they're stout, but could have some wear on them.

In my head, the only other possible way that you're going to hear that kind of noise is of something is going on inside the rear end. However, I think you'd have more happening at other times than just when you downshift.

[Pedigry]

Thanks Josh!

I am positive it's not in the rear end. The sound switches from the left to right and sometimes on both sides at the same time. I was concerned about the rear end rotating on me if I took both of the lower arms out. I guess I can take one out at a time and check them to see if there is visible wear there. If the bushings are worn, can they be pressed out and replaced? The other option would be getting new ones but I don't want to spend the money if I can just press them out.

I also wanted to switch out the top ones for 2 sided adjustable. I have been messing with the pinion angle and it's a pain to have to pull the rear coils, insert the metal brackets in place of the coils, then pull the upper control arms every time I want to adjust the pinion angle.

Thanks,

Lance

[Josh@Ridetech]

Thanks Josh!

I am positive it's not in the rear end. The sound switches from the left to right and sometimes on both sides at the same time. I was concerned about the rear end rotating on me if I took both of the lower arms out. I guess I can take one out at a time and check them to see if there is visible wear there. If the bushings are worn, can they be pressed out and replaced? The other option would be getting new ones but I don't want to spend the money if I can just press them out.

I also wanted to switch out the top ones for 2 sided adjustable. I have been messing with the pinion angle and it's a pain to have to pull the rear coils, insert the metal brackets in place of the coils, then pull the upper control arms every time I want to adjust the pinion angle.

Thanks,

Lance

No problem at all!

Doing one at a time will make your life easier for sure :D.

On those older bars, those bushings were ones that we had molded specifically for us and they're no longer available unfortunately. We do have the R-Joint upgrade bars available for guys with the older four links (and we can do them in double adjustable if you wanted to). Get with me directly and I'll help out where I can if it turns out that your bushings are indeed bad.

Thanks,
Josh