[1971-Chevelle]

I am hoping that someone can help me figure out why my front end shudders when I hit bumps or potholes. It just feels like all of the body parts are not connected. I have UMI adjustable upper control arms w/ heim joints, UMI lower control arms with Delrin bushings, 1.25" sway bar, and Viking double adjustable coil overs.

My coil overs are currently set at 6 on compression and 8 on rebound (I was at 4 and 6 respectively before the beginning of the month - I have noticed a little difference in the shudder, but not a whole lot). The springs are the 550 pound units (which may be too much for an aluminum headed small block car).

Would a frame brace up front help with this issue?? Some only tie the frame horns to each other, while others tie the frame horns and the cross member together (a design that I feel is better).

Would I be better off getting the 450 pounds springs from Viking and swapping them out?? Will the lighter springs react better over bumps??

If anyone has any ideas, your input will be greatly appreciated. Thanks in advance.

 

[shovelrick]

Hi Brian, what steering box do you have?

 

[1971-Chevelle]

Hi Brian, what steering box do you have?

Just a standard parts store gear. I don't feel it in the steering - the whole front of the car - hood, fenders, etc. - are what is shuddering.

 

[senna]

More info would be helpful.

What are the alignment specs?

Are all the steering components in good shape?

You mention adjustable upper control arms with heim joints? That would be rear control arms? I only know of one company that makes adjustable front upper control arm and that is SPC.

I don't see the springs being an issue, they could provide a firmer ride, but it's doubtful they're the problem.

A front frame brace can be helpful, but not a cure for issues like you're describing.

 

[MikeMalibu]

Your shock settings seem high based on my experimenting for street driving. Have you tried lower settings? Can you describe the shudder in more words? The 550 lbs springs will give a harsh ride with high settings on shocks, especially with low profile tires at high pressure. I have the same springs for my aluminum head small block.

 

[1971-Chevelle]

I really don't see how alignment specs will contribute to shudder. 0.17° total toe, -0.5° camber, 5.5° caster left, 6.0° caster right. UMI makes an adjustable upper control for the front (not fully adjustable like the SPC units, but adjustable).

1964-1972 GM A-Body Front Upper A-arms, Adjustable, 0.9? Taller Ball Joints [4056-3] - $629.99 : UMI Performance, Inc.

I have been running the shocks at lower settings until now and the problem was the same. My tires are 245/50R17. I run them at 35 PSI. The whole front end shakes - hood, fenders - everything. If I set the shocks lower, then the front end dips down way too low for my liking coming off of speed bumps, out of driveways, etc.

 

[NorCal-SS]

Which Viking series coil overs are you running? Are these a retrofit coil over or are they the true coil over with the upper mount? Hopefully you’re running the Warriors as they’re intended for street use and NOT the Crusaders. How low is your ride height? Is it possible the shocks are bottoming out?

 

[shovelrick]

I'd think a shudder would be in the steering components, tie rod ends, ball joints? but those are all in good shape? has anything been changed recently?

 

[HKalin]

I would take a look at the delrin bushings for wear and also the sway bar end links.

 

[1971-Chevelle]

Which Viking series coil overs are you running? Are these a retrofit coil over or are they the true coil over with the upper mount? Hopefully you’re running the Warriors as they’re intended for street use and NOT the Crusaders. How low is your ride height? Is it possible the shocks are bottoming out?

I am running the Warriors - retrofit. Ride height is fine - they are not bottoming out. Ground to fender lip is 26.75" - hub center to fender lip is 14.25".

I'd think a shudder would be in the steering components, tie rod ends, ball joints? but those are all in good shape? has anything been changed recently?

Nothing has changed. All of the steering components are in good shape.

I would take a look at the delrin bushings for wear and also the sway bar end links.

The lowers have only been in for less than 2 years - I don't believe the bushings are worn. The sway bar end links are new.



I should add that this car had the same problem when I was running all stock suspension with rubber bushings.

 

[lucifershammer]

If you can, get a GoPro (or some other camera) mounted and aimed at the front sheet metal, and hit a few bumps. Also, if you can have someone in front of you filming, do the same.

Maybe you are missing some body/fender bolts, maybe some are loose, etc. But if you can actually see the sheet metal bouncing around when you hit bumps, it may lead you in a different direction you haven't thought of.

 

[71350SS]

IF this was a stock suspension with stock parts I would immediately suspect shocks that have lost most or all of their oil and because of that, their dampening ability.If you ever test drive a car with bad shocks(or struts) and go over some bumps you'll feel that kind of shudder.
BUT with an adjustable shock you can add in some extra dampening in either compression or rebound.If you can try taking the front shocks to 50/50 and see if that helps some.
The other thing on a stock front end with a short arm long arm suspension would be upper control arm bushings and more likely worn out upper ball joints .
Go back to the basics and check your FE with the jack under the LCA to see if anything came loose.

 

[1971-Chevelle]

IF this was a stock suspension with stock parts I would immediately suspect shocks that have lost most or all of their oil and because of that, their dampening ability.If you ever test drive a car with bad shocks(or struts) and go over some bumps you'll feel that kind of shudder.
BUT with an adjustable shock you can add in some extra dampening in either compression or rebound.If you can try taking the front shocks to 50/50 and see if that helps some.
The other thing on a stock front end with a short arm long arm suspension would be upper control arm bushings and more likely worn out upper ball joints .
Go back to the basics and check your FE with the jack under the LCA to see if anything came loose.

All the parts are tight. The upper control arm 'bushings' are heim joints. How would I take the front shocks to 50/50?? There are 19 positions of adjustment on both compression and rebound. I am currently at 6 on compression, and 8 on rebound.

 

[71350SS]

I am not too familiar with your shocks but 50/50 would just be the same on compression as it is on rebound.So for 50/50 adjust your shocks to the middle of the settings with it being the same on both compression and rebound.So for 50% of 19 you would have to try both 10 and 9 on both settings since 9.5 is not available.
If the 50/50 setting gives you some improvement then you could adjust from there for the best setting.If it doesn't help it didn't cost you anything but time.

 

[temp2c]

I would get the frame brace Mark sells at SC&C...

 

[1971-Chevelle]

I was looking under my hood the other day and noticed something. I have a feeling that this might be contributing to the front end shudder. I am fearful that I may not be able to do the replacement easily, or that the steel part may be too far gone.

 

[NorCal-SS]

Is the where the radiator core support mounts to the frame? Yeah I would think that separated support would cause some front end vibrations

 

[HKalin]

The metal pieces should be bolt on items that you can buy separately. I would replace both sides and put new bushings in too.

 

[1971-Chevelle]

Is the where the radiator core support mounts to the frame? Yeah I would think that separated support would cause some front end vibrations

Yes, the core support bushings are shot (they are the originals, as far as I know).

The metal pieces should be bolt on items that you can buy separately. I would replace both sides and put new bushings in too.

The driver side bracket looks to be okay. The passenger side one may have an issue (the bracket appears to be further back than where the bushing it sitting).

 

[skreddy]

My passenger side was rusted out there and causing a loud thunk when going over bumps. My car is 68 and could not find just that replacement tab, needed to buy the whole core support. However, yours looks in way better shape and maybe new metal or a fender washer could be welded in place. In the event it’s not savable, I ended up buying one for a 64-67, which is repro’d. Looks slightly different but key measurements are the same.