[MJZ]

I’ve installed new ride tech coil-over suspension package on my 67 GTO.. My question is it rides like there’s no shocks or springs at all. I’ve backed off as far as I can without rubbing tires. Can someone guess what I’ve screwed up. I did the same on my 71 last year and it’s perfect but that time I went with Hotchkis.

[JLMounce]

Where did you set the ride height on the car? The ride height must be set in the operating range of the shock. If the ride height is set too low, you essentially have zero bump travel and your ride gets extremely harsh.

Setting proper ride height should be discussed in the instructions for the product you purchased.

[jwcfbd]

Originally Posted by JLMounce

Where did you set the ride height on the car? The ride height must be set in the operating range of the shock. If the ride height is set too low, you essentially have zero bump travel and your ride gets extremely harsh.

Setting proper ride height should be discussed in the instructions for the product you purchased.

That's what I'm thinking also. Sounds like you have taken all the weight off the springs. I put QA1 coilovers on my 67 Firebird and had to put quite a bit of load on the springs before they took the weight of the car and started working.

[MJZ]

Thanks, I’m going to check that this week.

[JLMounce]

Originally Posted by jwcfbd

That's what I'm thinking also. Sounds like you have taken all the weight off the springs. I put QA1 coilovers on my 67 Firebird and had to put quite a bit of load on the springs before they took the weight of the car and started working.

Perhaps not all of it, but enough that the shock is bottoming out.

Originally Posted by MJZ

Thanks, I’m going to check that this week.

Ridetech typically wants there shocks between 40-60% of the travel. 40% bump travel to 60% droop travel, or variations in that range with more bump and less droop.

Beyond this, you risk bottoming or topping the shock which will create harshness and degrade shock lifespan.

Street cars don't typically have issues with topping out shocks, unless the ride height is set ridiculously high. That is more of a drag car concern. However, bottoming the shock on cars that have been significantly lowered, is definitely a concern.

at the low end of the ride height range at 40% bump travel, typically the shock's compression needs to be increased to help deal with the lack of bump travel.

If the ride height is not where you want the car at the limit of where the shock needs to be, you have options such as drop spindles that will lower nominal ride height without changing travel limits on the spring and shock assembly.

If suspension component alterations like drop spindles are not possible, you can go lower in the shock's operating range, but you have to increase both spring rate and shock damping to control the weight of the car with that reduced travel. This does decrease ride quality, but it's typically better than riding on the bottom of the shock, which is like having no suspension at all.

This could include going to a shorter shock body to accommodate a shorter/stiffer spring, but again, that degrades ride quality.

For the best combination of ride quality, ride height and handling characteristics (outside of a racing application) targeting the longest shock, with the lightest spring rate and enough compression/rebound damping to control that is key. This is why you see systems like Ridetech using a dropped base lower control arm. This allows the shock to be mounted in such a way that the shock body can be increased in length, allowing a longer spring with less spring rate.

I do want to point out that when I say less spring rate, I really mean, less of an increase over the factory equipment. From the factory, these cars are woefully undersprung and damped.

[MJZ]

Great information, thank you very much.