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Old 11-23-2021, 08:49 AM   #1
FreeEMSFred
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Default 700/900 wagon IPD lowering springs centre support spacing

How high should I lift the driveshaft centre support with these super-common springs?

I have:
  • Done some experiments with 0, 6mm, 10mm, 12mm
  • Asked IPD what they recommend

What do you recommend? What did you find works best?

I could also test 3mm, 8mm, 9mm and 14mm - but didn't yet.

Need to repeat the ones I did do with more gentle driving - not just hard first gear accel from stop to redline.

Thoughts?
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Old 11-23-2021, 08:50 AM   #2
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IPD article simply says -4mm to +12mm - and no more. But it's general advice for all lowering, not their particular kit.
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Old 11-23-2021, 09:17 AM   #3
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I lifted it about 10mm ballpark with my -40mm springs, which is not really enough in my case.

It still drones between 70-90kph but it's bearable with no load in the car.
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Old 11-25-2021, 10:17 PM   #4
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Interesting - I got zero above 60kph ie in 2nd gear or higher with no spacing. I feel like you might have a bad bearing or U joint or balance issue as well/instead?

But 0-60 with hard accel eg flooring it or pushing against hill or trailer was pretty bad and seeming to get worse as the rubber loosened up

Adding 10mm mostly solved it, no or not noticeable hard accel issues, but light accel first 10-20kph it did shake a little as I discovered later.

Adding 12mm seemed similar but I want to test for light accel see if it's cured

6mm was moderately bad under hard accel but a lot better than 0mm was.

I have modified the old centre support from the 960 by stuffing it full of window structural silicone and it's about half way through curing now. Probably good enough to install.

But before I do that I want to understand what the loose version does ie I want to get the geometry right first then stiffen it up.

after all the testing I just added the 10mm ones back in and then a few days later used it - that's when I noticed the shake under light accel - I had only tested under heavy accel, oops.

The thing with these old OEM supports is they're SO soft that ANY slight imbalance throws them into a low earth orbit AND they sag - so spacer is firstly offsetting the sag of say 4mm and then correcting after that. I need to measure the exact sag amount once I get the unmodified shaft back out again. But ball park, that's about right.

I'll use "successful spacing with loose/saggy support" minus "sag" = spacing I should run with the modified one.

Any other data points out there?

Cheers.
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Old Today, 05:34 AM   #5
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Tried 13mm today with the soft 740 shaft and unmodified centre support and that was perfect as far as I could tell. There was some shake up around 140kph but I don't know if it was coming from the driveshaft and I don't usually go that fast anyway, just for testing. Sag in that shaft was 3mm so I'll be running 10mm with the modified/filled/reinforced support in the original shaft when it goes back in tomorrow or in a few days. IE, 13 - 3 = 10. 3 making up for the sag, 10 additional height.
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Old Today, 12:28 PM   #6
ZVOLV
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I would put it up on the drive-on lift and measure the u joint working angles.
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