Rear End Rub and harsh ride

[33PizzaGuy]

Hey gentlemen, I am BACK. The car is fully built and painted. Just waiting on registration and wire my power windows. Oh, and I am tuning the Holley Sniper so I am doing some data logging for my tuner guy. Anyways, I think I sent a picture of my car before but I will try it again.

The issue I am having is when I hit the smallest of bumps the car sounds like its biting me in the ***. Sounds like the rear coil springs are not long enough or something. I have the supplied KONI no adjustable shock with I believe the #250 rear spring and the collar adjustment is barely applying pressure on spring so I can get more clearance. If I tighten the collar to compress the spring it lowers the car and stiffens the ride. Any thoughts on this and what length of spring should I get? Maybe #250 is good but need longer. Now when I drive the car with just me its better about rear wheels hitting bike fender but today I had my dad and it was bad. Not sure what to do here. Any input would be great. Thanks guys

Scott

[33fromSD]

Beautiful!!

Simplest answer to your problem is dump the Konis and go with a better shock. I went with QA1 prom star double adjustable shocks on the front and single adjustable on the rear and then went with a different spring combo. NAZ on this forum was a HUGE help with getting me dialed in.

* Front = QA1 DD403 Proma Star Double Adjustable coil over shocks with 9" long 300# springs (if you invert the front you'll need a couple extra items)
* Rear = QA1 DS601 Proma Star single Adjustable coil over shocks with 12" long 300# springs

Also, I had a bad rubbing problem in the back too on the full fenders until I did the above but I also added a 2nd bump stop in the shock shaft which resolved my rubbing issue. Now that I know that works, eventually I'll replace it with a single bump stop the same length as the two combine but for now I'm just enjoying the non-rubbing ride.

Keep tweaking, you'll get it. We are never really "finished" with these rides, we just make them better as we go. :rolleyes:

Jim

[edwardb]

If I tighten the collar to compress the spring it lowers the car and stiffens the ride. Any thoughts on this and what length of spring should I get? Maybe #250 is good but need longer. Scott

That's backwards. Tightening the collar on the coilover raises the ride height and should give you more clearance. Tightening compresses the spring and the resulting force pushes the suspension up. Can't say how much it affects the ride, but kind of a moot point if you're dragging things. There are perhaps better shocks out there. But I wouldn't be in a rush to change them ($$$) if the issue is simply that your ride height is too low.

I'm betting your '33 Hot Rod has the same shocks and springs as my 35 Truck build. The pictures look the same. The Koni 82 series shocks are adjustable. https://www.koni.com/en-US/Cars/Technology/Adjustment-Guides/. May not help, but just FYI. Based on your picture, you are near the top of the adjustment on the coilover. My truck is the same way. The kit comes with 8" 250# springs. It's probably possible to install 10" springs (the next available size) which I'm considering maybe for my truck. Going to wait and see once it's on the road. Eibach EIB-10002500250 or EIB-10002500250S at $75 each a relatively inexpensive possible upgrade.

Your Hot Rod looks great BTW!

[33PizzaGuy]

Thank you Jim and Edward. The exact answers I was looking for. I actually meant everything the opposite as far as tightening the collar. So, I have now in hand are the Proma Star single Adjustable coil over shocks with 12" long 300# springs for the rear. I will install Sunday. Thank you

Scott

[33fromSD]

Thank you Jim and Edward. The exact answers I was looking for. I actually meant everything the opposite as far as tightening the collar. So, I have now in hand are the Proma Star single Adjustable coil over shocks with 12" long 300# springs for the rear. I will install Sunday. Thank you

Scott

Did you get any additional bump stops? Changing out shocks isn't too big of a deal but why do it more than once.

The beauty of the bump stops is you can then run the suspension as soft or as stiff as you want and the bump stop will prevent the bottoming out.

Good luck.

Jim