Author Topic: AC MKIV Shock/Ride Height problem  (Read 302 times)

lonzo

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AC MKIV Shock/Ride Height problem
« on: July 31, 2019, 16:27:25 »
Several years ago I replaced the shocks on my MK IV because they were leaking.  I used Spax G953 on the front and G952 on the rear.  I think the shocks came assembled with springs but am not sure.  I now have the spring adjustment ring as low as it will go but the ride height is still 1-2 " too high on three corners and 2-3" on the right front. Any suggestions on how to fix this problem? Where could I get shorter springs? What are the spring specs (spring rate etc.)

westcott

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Re: AC MKIV Shock/Ride Height problem
« Reply #1 on: August 02, 2019, 14:36:04 »
AK 1106 still has the original Koni shocks and springs. No idea what specs Spax units should have to fit the MK IV.
Everything should be made as simple as possible, but not simpler!

Flyinghorse

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Re: AC MKIV Shock/Ride Height problem
« Reply #2 on: August 05, 2019, 12:55:03 »
Lonzo,
You dont state where you are (For specialist options)  or if car LHD or RHD or if on 16" or 15" rims& tyres.

The front RH corner being higher -is that with fuel & driver in car (if RHD) as this may explain that.
16" and 15" set ups will change the ride height without touching anything else.

What made you decide its to high given you have had it like this 2 yrs?

There are /were  shorter uprated springs available  (about 1" shorter) in period, and I have some on my CRS with Konis. You say you dont know if the springs came with the Spax so theres another potential source of discrepancy.
An autokraft drawing from 1985 I have shows the Front spring as D1112 length 11.52" (free) 10 coils and the rear(D1143) free length 12" and 9 coils.
For reference my springs are 10.25" free length front & back. These are Uniclip uprated (+25%)springs supplied by Thunder road)

If you have the original konis they can be rebuilt (I have the contacts) and you would be able to see if they have springs and make comparative measurements to the spax.

If in the UK there are specialists who know this stuff and have spares in the ACOC magazine.
Graham

« Last Edit: August 05, 2019, 13:17:01 by Flyinghorse »

lonzo

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Re: AC MKIV Shock/Ride Height problem
« Reply #3 on: August 12, 2019, 15:21:19 »
My car is LHD and has 16" wheels.  I bought it new in 1985 and it came with Spax shocks from the factory. I replaced the shocks with new Spax units since the old ones were leaking. After several attempts by the garage which originally installed the replacement shocks the ride height with or without a driver is visibly much higher at the right wheel. I checked with Spax and found out the replacement shocks did not come with new springs which means I still have the original springs on my car. All four shocks are adjusted as low as the adjustment ring will go.  LC

B.P.Bird

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Re: AC MKIV Shock/Ride Height problem
« Reply #4 on: August 12, 2019, 20:05:18 »
Lonzo,
I wonder if the 'high' corner damper is faulty, or in some way mismatched and is holding the suspension up ? Perhaps you should take both front spring/damper units off and compare them. Important: Do not muddle them up. First compare the complete assemblies, then demount the springs and compare the damper stroke from full extension to full compression. Check the part numbers match. Compare the springs for damage, height, turns and wire diameter. Compare the spring perches. If you find the answer that's fine, if not reinstall everything back on the car, but reversing the original position side to side. Now see which corner is high. If it is now the other side the fault is with that spring, or damper. If the high corner remains on the original side it may be a rear spring or damper which is hiding the problem. Possibly, although less likely, is there incorrect assembly or damage on the chassis or suspension ?
As you say all four corners are now higher I would suspect that the dampers have longer lengths of 'buffer' rubbers at the end of the compression stroke. If you have the old dampers that would be another useful comparison, you can see the buffers at the top of the damper on the piston rod. Have you asked Spax for details of what they have sent you, it might be that they have got it wrong, do you know how those part numbers were generated ? They are not the numbers they list for a Cobra, possibly they are a custom specification to suit the coil spring chassis ?
Last unlikely possibilities: have you got three rear dampers and one front or three fronts and one rear, or a front and a rear on each axle ? Clutching at straws here.....
Barrie

lonzo

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Re: AC MKIV Shock/Ride Height problem
« Reply #5 on: August 14, 2019, 21:32:55 »
Barrry,
I have checked with Spax and they say the shocks I received are the correct ones for my AC. I couldn't remember if they came with springs or not.  According to Spax the new shocks did not come with new springs. This means we put the old springs on the new shocks. What I can't understand is why the car now sits higher with the original springs and new shocks.  The gap between the tire and the fender is approx. 2" on the rear and left corner but is approx. 3 1/2" on the right front even though the adjustment rings are all the way to the bottom on all.
Lonzo

Flyinghorse

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Re: AC MKIV Shock/Ride Height problem
« Reply #6 on: August 14, 2019, 22:11:03 »
Lonzo ,
Has the car been jacked up at all as the split lock collets that hold the spring to the shock can become unseated if the spring is set loosely. Might be worth checking , but as Barrie suggests you will have to start at the front , tyres off and start comparing each side/working out firstly why one side is higher than  the other.

Graham

lightblue

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Re: AC MKIV Shock/Ride Height problem
« Reply #7 on: August 16, 2019, 14:06:13 »
Lonzo,
My 1985 MKIV also has Spax dampers and I can confirm you have the correct part numbers.
Just a thought - have you checked the clerance from the ground to the underside of the forward ends of the chassis tubes?  If they are equal the problem is more likely to be related to body mounting or wheel-arch shape.
John.