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Lowering standard spring perches?


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#1 zzzzed

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Posted 11 March 2015 - 05:36 PM

I don't like the 4wd stance my 2 seater has right now.
What I was thinking was to use standard springs to keep the smooth ride but to lower the spring perches
And section the struts.
Is this a viable option?  If so from what car do I steel the strut inserts from?

#2 gilltech

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Posted 11 March 2015 - 06:24 PM

It's a LOT less work - & expense - to just get your existing factory springs re-set shorter. Spring places do it, they re-temper them & alter the length if you want (within reason). The number of coils stays the same, the wire X-section stays the same, so doesn't stuff up the spring rate, the spring just acts through a different range.
I had that done to the fronts on mine, IIRC 25mm, & for the back ones I trimmed IIRC half? a coil off which, I calculated at the time, stiffened the spring by about 5% to reduce rear squat & lowered the car the equivalent amount to the fronts.
In my case I was limited by a flat-to-slope transition on my driveway, so the above left me with barely 10mm clearance with car laden 2 people & full tank. And I had factory 14" mags with 195 tyres.
Your situation may be somewhat different. I'm assuming you aren't looking to slam the car! In any case, measure it all up carefully first before you make any changes.

#3 44014

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Posted 11 March 2015 - 07:20 PM

If you lower the car and don't harden the spring your just going to bottom out all the time and the car will handle horribly....
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#4 zzzzed

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Posted 11 March 2015 - 07:35 PM

If you lower the car and don't harden the spring your just going to bottom out all the time and the car will handle horribly....

.
That was on my mind. I guess if it was that simple every one would do it.
I might just buy king spring super lows.

#5 44014

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Posted 11 March 2015 - 07:42 PM

I happen to have some for sale... With adjustable koni inserts to go along with them.


#6 PZG302

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Posted 12 March 2015 - 07:57 AM

On my old race Zed the standard spring perches were cut off and rewelded onto the struts about 50mm lower using the same springs it had before. However, the springs were made by Lovells to suit the rate needed and the height. The advantage it gave me was the same length of travel in the suspension for a 2" drop in static ride height.

In terms of hitting the bump stops it wasn't an issue as it was a track only car and the spring rates were very stiff for a Zed, 450lb/inch on the front and about 400lb/inch on the back.

The big disadvantage is that the spring perch is lowered meaning you have to be much more careful in wheel choice, especially if running big diameter wheels. I hade a 3-4mm gap to the tyre side wall running 18x8" rims with a negative 3mm offset. I was lucky that the slicks I used were the equivalent of a 30 series tyre and had a very stiff sidewall any way.

This was done because the options weren't available over 15 years ago when the car was built, so today I would do it properly and go the way Doug and Jake have with properly set up coilovers.

#7 Howdy

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Posted 12 March 2015 - 10:23 AM

Don't just get shorter springs. The best thing to do is to rip out your springs and bump stops on one side, disconnect the sway bar links, reassemble your suspension and wheels then measure how much bump travel you will be left with when you lower your car by jacking up the wheel until it stops. I've found on both '75 and 74 260 2 seaters there was very limited bump travel left even when I only lowered the car slightly.

I drove my '75 260 for years wondering why no matter what brakes I ran, it would never pull up well. Tried so many bigger brake combos, balance valves, pads etc but it would just not pull up as hard as it should have. I developed an uncanny talent for finding appropriate escape routes in corners, between tire walls, Marshal towers, trees and rockeries. Eventually worked out it was bottoming out at the front under brakes.

The only solution, especially if using softer springs, is to cut the struts and use shorter inserts. To give you an idea, in my case for my 1000Kg '74 260 race car, on which I run soft springs (F182lbs/in, R 210) I think I cut about 145mm from the rear and used the front inserts and about 50mm from the front and used VW golf inserts. Not sure which model Golf but it would have been an older model. This gives me a total (with bump stops removed) of 130mm bump on the front and 150mm on the rear. On a smooth track like Phillip Island I use up 90mm of the front and 135mm of the  rear bump travel with standard size bump stops installed (about 40 - 50mm long I think). Your car with standard springs, extra weight and rougher roads but less grippy tyres will probably use a little more not counting pot holes, rocks and small fury animals.
You can cut above or below the spring perch but that will depend on your spring length and wheel size for optimal clearances. Watch out for inner wheel / tyre to spring clearance and coil bind. With soft springs you probably want at least 100mm of bump before hitting the bump stops which should be gradual, not just a solid lump of rubber.

Spend some time measuring it up and you will avoid some mysterious handling problems which will make your car unpredictable and dangerous.


#8 gilltech

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Posted 12 March 2015 - 05:10 PM

I might just buy king spring super lows.

If you just want to lower your car a small amount so it looks right, then have a think about my feedback above, simple & cost effective.
But if you are looking to lower it substantially, as many have done, then it's not that simple because there will be flow-on effects such as with wheel/tyre combinations & clearances, & especially wheel alignment.
Be careful. People buy the king springs then find that they are substantially shorter than stock, to the extent that with some models they are no longer 'captured' by the spring retainers when the suspension is at full droop (such as up on a hoist), AND in order to lower the car without causing bottoming-out problems you will find that they are substantially stiffer than stock, so harder riding. There are other posts on this forum about that which would be worth reading.
Also, with 240's & 260's there are quite a number of different stock spring rates used by the factory depending on whether the car has A/C or not, which market it's sold new in, which suspension option (sports, etc) is fitted, 2 seat or 2+2, etc; have a look in a Z parts manual & you'll see what I mean. Who knows what your car has? King springs simplify it all by just offering 2 choices for 240s & 2 for 260s, & the 'standard' option inexplicably uses the same rate as the 'lower' option. You won't know what your new ride height will be until you try them.
I tried a set of king springs for my 260 2-seat, the '30mm lower' version; ride height actually went up, front springs were too short as weren't captured, & both ends were too stiff (which is why the ride height went up). So I took them off again, I want my suspension to work as designed not sit on a rigid board which has little give.
So proceed carefully.

#9 zzzzed

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Posted 12 March 2015 - 06:29 PM

All I want is for the tops of the guards to be level with the top of the wheels

#10 zzzzed

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Posted 12 March 2015 - 06:49 PM

My car currently sits high enough that it has slight posative camber on the rear.

#11 Howdy

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Posted 12 March 2015 - 08:01 PM

All I want is for the tops of the guards to be level with the top of the wheels

Man that's low :o might smoke a bit going down the road.
Seriously though, if you have 14" wheels and want the wheel to the top of the wheel arch, I reckon you'll only have about an inch of bump, if that. One thing I'm confused about is that you said "standard springs" but why is it sitting so high at the rear? Did you replace the original struts? Those old springs should be sagged out a bit by now.

#12 zzzzed

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Posted 12 March 2015 - 09:58 PM

The car has been inu family for 10 years or more and the springs have never been out of the car in that time
It's is running 205/60/15 on 8" zero offset rims.
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#13 gilltech

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Posted 12 March 2015 - 10:59 PM

It does look a touch high compared to what we're used to today, but I'd say that looks about stock; I have the same, '74 260Z 2-seat, since 1984. As per my first reply, I lowered my car about 25mm both ends. I can barely slide my fingers under the guards & over the tyre. I reckon I've got it about right, rides nicely, not so low that suspension travel is compromised.

#14 cracker

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Posted 13 March 2015 - 08:26 PM

If its an early enough car to use the 240z suspension, I have a set of lovells and a set of king springs (both "low") that you are welcome to test fit.

#15 zzzzed

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Posted 13 March 2015 - 08:32 PM

Thanx mate. I have been offered a set in exchange for some welding.
I will wait untill he is ready his car is the same year as mine and sits very nice so
At least I know they will be what I am after.

#16 MaygZ

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Posted 15 March 2015 - 01:18 PM

I'm going to just put it out there:  have you considered reducing the thickness of the rubber cone thingy at the top of each strut?  You can easily take 3/4 to an inch out them and it simply lowers the body on the suspension.  No spring changes and it should also bring the camber back in.

#17 dat2kman

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Posted 15 March 2015 - 02:47 PM

Very easy to open up strut top, and remove half the rubber, trim metal back, slit the ketal cup, and fold it over so that it still retains the strut.
Very common tip woth race cars that retain stockish suspension.
Tha'll give you 3/4 to 1"
Then remove half a coil off your stock spring at each end, heat and reshape, and wire top and bottom of spring to perches.
Rough, cheap and effective.

#18 zzzzed

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Posted 15 March 2015 - 06:06 PM

That's a good idea. I have thought of it and was only talking about it with some people today.

#19 Rick

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Posted 15 October 2015 - 09:06 PM

Any chance of a drawing .
Cheers.




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