Ridetech rear suspension bottoms out on bumps

[CamaroJesse]

I just got my car out on the road 2 weeks ago and im loving it so far. i know that its going to take some time to tune the suspension but im looking for some tips. its a 67 firebird with full ridetech stage 2. When im out on the highway doing about 60-70 and i hit a bump the rear end will hit the ridetech rear crossmember. it doesnt seem to be smacking it too hard but definitely hitting it. the car sits low but no lower than the rest of the cars are sitting so im hoping i dont need to raise the car to fix this. what exactly do the adjustment knobs do on the shocks? do i need to stiffen them up maybe or could i possibly have the wrong springs? i cant recall right now what pound springs i have i would have to look but they re one step stiffer that what the ridetech kit comes with if that helps.

thanks
Jesse

[F-Body International]

Shock will probably need stiffening on compression. Doing this slows down spring compression. You may need to step up to a stiffer spring.

A lot of people have been raving about soft springs on this website recently. There comes a point where things become too soft. This is more of a problem when you lower a car (decreased spring travel).

[Tom5410]

CamaroJesse,

I am curious to what rear end you have.. My Dana-60 does the same thing in my 67..

[CamaroJesse]

I have a Moser 9 Inch with a top fill and the cap is hitting the cross member.

[darren@ridetech]

Let's check a few things.
1. How long are the shocks from center eye to center eye with the car at ride height?

2. How tall is the spring at ride height?

3. The springs do have the rate printed on the side of them, verify rate.

4. Axle to frame at ride height.

5. Fill cap to cross member at ride height.

The knob mainly adjusts the rebound dampening of the shock. What do you currently have them set at? Around 12 clicks from full stiff (clockwise) should be enough to prevent excessive body movement.

[CamaroJesse]

1. How long are the shocks from center eye to center eye with the car at ride height? 14 1/2 inches

2. How tall is the spring at ride height? 9 3/4 inches

3. The springs do have the rate printed on the side of them, verify rate. part number-1812b0200

4. Axle to frame at ride height. 3 3/4 inches

5. Fill cap to cross member at ride height. 2 inches

[Josh@Ridetech]

1. How long are the shocks from center eye to center eye with the car at ride height? 14 1/2 inches

2. How tall is the spring at ride height? 9 3/4 inches

3. The springs do have the rate printed on the side of them, verify rate. part number-1812b0200

4. Axle to frame at ride height. 3 3/4 inches

5. Fill cap to cross member at ride height. 2 inches

Hey Jesse,

From looking at all of your numbers, the shocks, springs, and axle to frame look good.

The biggest problem that I see is the fill cap to cross member, it's limiting the compression travel. The suspension has the correct amount of movement but with the way your axle housing is built, it's running into clearance issues sooner than a stock housing would. There are a few ways that this could be solved (some easier than others). The ideal situation would be to find a way to get your compression travel back and have clearance but it would take some modification on the housing or crossmember. Can you post a couple of pictures of the fill cap clearance that you have at ride height please?

Thanks,
Josh

[bret]

If I remember correctly, that Moser rearend has a fairly large cap that screws into the fill port. You might be able to find a different cap with the same thread size but a smaller head on it that would provide more clearance. I'm thinking something with a recessed allen head that would sit flush with the bung when tightened. It would not be as handy to remove, but you likely do not fill your rearend that often anyhow.

[CamaroJesse]

im thinking im going to have to notch the rear subframe to make it work. luckily its not hitting that much so i shouldnt have to notch much. ill do it over the winter.

[TheJDMan]

Before you start cutting anything just try increasing the shock compression a couple of clicks. My Moser 9" fill cap will hit the rear frame crossmember once in a while and I have about the same 2" clearance.