Variable rate springs for Harrison

[macloft]

Hola
Looking at the QA1 shocks for the back of my Harrison. Question is springs.
Has anyone had experience with Variable rate springs on a Harrison and if so what strength did u use? the 175/ 350
I find with the AVOs and the 250 spring I have the ride is to harsh for the road
Thanks Bruce

[OZVENOM]

Hi kings springs make 2 types of progressive springs single and double taper.
These work very well you just have to make sure you can get the right length because if you compress the spring to fit it it stops being progressive and acts like a normal spring. a lot depends on how much you compress it.
hope this helps.
oz.

[macloft]

Hi Oz
So if the car currently has 250 rate springs do you know if i use a 175/ 350 would that give me a softer ride for the initial smaller bumps i hit and then stiffen out.
I find right now the back bangs a little to much even if i soften the shocks down.
I am bringing shocks and springs over from the US with me when i go back to Brissy for a couple of days R&R.
Thanks
Bruce

[Merv and Sharon]

Bruce, the longer shocks and springs should do the job, however, I also tried some keeper springs before I went for the 12" shocks and springs at the rear. There was an earlier thread: spring rates

[aussiecoupe]

Hi Bruce
We allways suggest 350 lbs on the front and 300 lbs on the rear . I have just had an engineer do a road test for rego . His 15 kms test run is like a goat track at the back of Lismore NSW . He was quite pleased as with others with the ride and handling . Unsure where you are driving the Cobra . I would suggest you talk to either King spings
or a spring manufature about the progress spings . One of the Cobra racers is trying Penski shocks to see if he can inprove his times with the two adjustment style . Do not forget the AVO is rebuildable and REg can alter the valving . The others , well look into if they can be rebuilt . We had some problems with leaking shafts but those have been fixed under warranty .

Warwick.

[Merv and Sharon]

Hi Warwick. Catch up with you at Twin Waters in November. We need to have celebration when Rog finishes number 100!

[macloft]

Hello Warwick
Thank you for responding
I have tried to call a couple of times but very difficult due to time difference and my Mexican phone.
I will try again today. I am coming over in a week and have arranged a couple of days to work on my car to finish a few things off and take it for a drive.
Cheers
Bruce

[macloft]

Hola
Just to close out this thread. I have spoken to Warwick and decided to go with the QA1s for the extra 1 inch travel (17") over the AVO. I dont want to compromise the ride height of the car by using to short a shock. I am going to use the QA1 single adjustable shock as I am no suspension wizard and it's not a track car. I do believe there will be enough adjustability to suit my needs.
I am also most likely going to use the standard 12" long coil spring at the 300 lb spring over the variable spring.
Does anyone actually have hands on experience between the handling difference between the variable and fixed springs on a road car. My intuition tells me u probably would not be able to feel a difference through ya butt.
Now to talk to my bank manager
Thanks Warwick (and others) for your response and help.
Cheers
Bruce

[400TT]

Bruce, what settings did you have your shocks set to. It's not as obvious as shocks set too hard.

Going to longer shocks is a great idea.

Just a heads up the QA1's are a very stiff/hard shock, so you will only be using the lower part of the adjustment range.

[macloft]

Hello Craig
The AVOs were set in the middle setting
The real problem I have is, to get the car at the right height to pass inspection (4 inches) i had to jack the back up until the rear shock was almost fully extended. So when I am driving the car and the shock rebounds over a bump the shock would fully extend and bang.
Certainly when the car was lowered I could get the setup to work right.
Maybe I got to short an AVO. I do not have an issue with the AVO itself or the spring I believe I have wrong length.
Cheers
Bruce

[400TT]

Bruce, know exactly what is wrong, performed the same mods but Warwick would have covered that with you.

I'm just giving you a heads up if you are changing shocks.

Haven't used AVO's for a very long time, so don't know how hard they are. But with the QA1's, don't get too carried away on the number of clicks you put into the shocks, start soft and work your way up, don't start half way. Hope that helps.

[muzzza]

I have 17" QA1 shocks on the rear of my Harrison, with 300lb 250 long springs. Have also fabricated spring mounts that bolt onto the chassis. ( front and back ) This means I can easily fabricate brackets to raise or lower the spring mounting point, and hence the car ride height.

This solves any spring / shock compromise settings. eg "winding up the spring pre-load to raise the car "

Unless you run a circuit car set up for zero droop, you will only need sufficient pre-load to keep the spring firmly in place when the suspension goes into full droop. When you pre-load a spring for no other reason than raising the car height....it is NOT THE THING TO DO. It also changes the the linear properties of the selected spring. QA1 shocks blow apart very easily with too much spring pre-load.

With too much pre-load and not enough droop, it is not too hard to lift a rear inside tyre and "Rotate"......when the tyre does make contact with the road surface again, the spring will not take up the loads progressively / smoothly as you have wound up too much pre-load. ( a 250lb spring acting like a 350lb spring )

I would stick with 17" shock ( easy to shorten shock or put in a droop limiter ) and 250 long spring.....possibly with a spacer under the top spring seat. 300 long spring may be a little too close to lower suspension arm, if you are running a skyline rear end. MUZZZA

[macloft]

Hello Muzza
Good comments. I would like to see some pictures of the top mount if possible. Thanks Bruce

[Merv and Sharon]

Yes Bruce, Murray is one of the most knowledgeable people I know on these things. Very experienced. I followed his advice with my shock set up at the rear, although his rear mount setup is much better.

[muzzza]

Meant to say.......QA1 do 1" and 2" alloy shock extensions that bolt onto top of shock shaft.........could be an option. I have some 4140 ( steel ) 1" extensions that I turned up a while back, if you decide that may be an option for you.
Will take pics of shock mounts tomorrow.
Muzzza

[leroy17]

Bringing up an older past thread.

Muzzza, If you ever get a chance I would be interested in pics of the shock mounts that you mentioned above.

Cheers mate.

[muzzza]

Lee, I have a two ( very average ) pics in my gallery. The rear brackets were cut off and a plate was welded in place with threaded holes for a bolt on bracket. At the front ...... I cut back original mounting plates and bolted on new ones with the upper shock eye relocated downwards. If I want to change ride height, I can remove the plates and re-position the holes.

[leroy17]

Thanks Murray, pics are perfect and confirms what I thought you had made.

Thanks again.

[sambo]

Reviving this thead again. Bruce, how did you go with the spring upgrades?

I have QA1 shocks on the rear with 250lb springs, which I've pre-loaded roughly 20-25mm for ride height. Cruising around on the street it's too jittery in the rear, so I'm considering a beefier spring with less pre-load.

Options from QA1 include 300, 325, 350 and 400lbs.

For Harrison owners with the Nissan rear end and 12" shocks, what springs are you running and how is the ride quality?

[leroy17]

On my previous Harrison number 40, and hopefully the new owner may comment as well. I used QA1 with 300 (f) and 275 (r) for memory, or maybe 250 (r). There was minimal preload and the adjusters were set at 5 clicks (again for memory).

Either way, it drove very balanced and stable and I would not have changed a thing from this setting for street driving.

Perhaps the adjusters could be backed off a little, just a thought.

I