Ohlins DFV 16kg - RX7Club.com



Ohlins DFV 16kg

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Old 03-19-17, 08:47 PM
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Ohlins DFV 16kg

Just finished installing a set of Ohlins DFV revalved for 16kg springs from the factory. At 7 clicks out the overall ride quality is similar to the Bilsteins they replaced which were 8kg front and 6kg rear. The increased spring rate is noticeable over large bumps and undulations but is otherwise relatively comfortable.

The chassis is much more tightly controlled, reacts to inputs faster and has very little understeer. Overall the car feels smoother and easier to drive. I will post some more thoughts on the handling when I've had a chance to go for a longer drive.

Here are the dyno graphs for the front and rear shocks showing 0, 7 and 20 clicks from full stiff. The left axis is in Kgf.



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Old 03-26-17, 05:43 AM
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I did a few hours of driving today, hopefully this feedback will be useful.

Through uphill hairpins, the inside rear wheel spins more easily. I expect this is due to the reduced droop travel.

There are several mid corner bumps that used to bottom out the car quite violently. The rear is now stiff enough to resist this but the front tyres still touch the inner fenders over the biggest hits. Does removing the inner fender liners give much extra clearance?

It's hard to give feedback on the balance of the car as the grip level with semi slicks is high. Through slower corners it rotates a little better and turns in more sharply. At low speed the car feels more agile, however in longer bends the reduced roll angle gives less feedback.

In terms of comfort, for the most part I find the spring rate easy to forget, and the bucking from the driveline is less irritating now that it is more strongly damped. I wouldn't recommend them for a daily driver over rough roads, but for a weekend street and track car I think they are acceptable.

I will add some more comments after I have been to the track.
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Old 03-31-17, 05:02 AM
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Interested in the update after track use.

Also, how may miles have you had with these shocks for now?

Are they properly run in yet?

Thanks,
Konstantinos.
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Old 03-31-17, 10:38 AM
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*You should remove your fender liners and relocate the wiring harnesses up above the unibody sheetmetal level if you haven't done this already. The wire harness just hangs on top of the plastic fender liner stock and gets rubbed through.* I put my liners back in after. My RX-8 is missing a liner and you don't want to run that way. Trimmed would be fine, but missing fills the unibody, fender and door jamb with rocks and leads to more damage.

Does removing the inner fender liners give much extra clearance?

It depends on where the tire is contacting the fender liner on how much extra travel you will "gain" (a big bump will blast your tire into the plastic hard enough to push it against the metal behind it).

On my set-up (18x11 +45 w/ 295/30-18) the tire rubs the fender liner where it is hanging down between the upper two outboard mounting points. If your tire is rubbing in this outer area because of its rounded shape or being unsupported (as in my case) you can just trim the liner back.

If your tire is rubbing the very top deepest part of the fender liner removing the liner won't gain you much travel.




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Old 03-31-17, 09:29 PM
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Quote:
Originally Posted by Nabu View Post
Interested in the update after track use.

Also, how may miles have you had with these shocks for now?

Are they properly run in yet?

Thanks,
Konstantinos.
I've done about 300km on them.

Quote:
Originally Posted by BLUE TII View Post
*You should remove your fender liners and relocate the wiring harnesses up above the unibody sheetmetal level if you haven't done this already. The wire harness just hangs on top of the plastic fender liner stock and gets rubbed through.* I put my liners back in after. My RX-8 is missing a liner and you don't want to run that way. Trimmed would be fine, but missing fills the unibody, fender and door jamb with rocks and leads to more damage.

Does removing the inner fender liners give much extra clearance?

It depends on where the tire is contacting the fender liner on how much extra travel you will "gain" (a big bump will blast your tire into the plastic hard enough to push it against the metal behind it).

On my set-up (18x11 +45 w/ 295/30-18) the tire rubs the fender liner where it is hanging down between the upper two outboard mounting points. If your tire is rubbing in this outer area because of its rounded shape or being unsupported (as in my case) you can just trim the liner back.

If your tire is rubbing the very top deepest part of the fender liner removing the liner won't gain you much travel.
Thanks mate, I removed the fender liners and tucked the harness above the sheetmetal. The liners are only a few millimetres thick where the tires are rubbing so I'll definitely put them back in.

I have done some measuring and by my calculations the front bumpstop needs to be spaced down quite a bit in order to be effective. At a ride height of 25.5" I have 30mm of droop, 70mm of bump before hitting the fender liner and at that point there is still another 30mm before the bumpstop would be engaged.

I will have to double check these figures but I've attached my spreadsheet with the rough calculations. I will likely put a 42.5mm spacer in the front and a 10mm spacer in the rear so that both bumpstops are engaging at around the same time.

I estimated the behaviour of the bumpstop using data from another Ohlins bumpstop of a similar size.
Attached Files
File Type: xls
Shocks.xls (38.5 KB, 3 views)
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Old 04-01-17, 12:56 AM
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What front tire are you running?
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Old 04-01-17, 01:33 AM
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255/40r17
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Old 04-01-17, 11:40 PM
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That is the correct diameter tire...

And you calculated the suspension motion ratio into it when seeing how much travel there was to the bumpstop?

So, not just like "I have 2" from top of tire to top of fender and 2.5" from top of shock body to bumpstop." type of eye-balling?

Hard to see how Ohlins would F that up you know...
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Old 04-04-17, 12:35 AM
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At full droop I measured 3.25" shaft travel before the bumpstop. Dividing by the motion ratio of .63 gives roughly 5" travel at the wheel. Unless I'm mistaken, if you have less than 5" travel from the wheel to the inner fender, the bumpstop won't engage. I will remove the springs so I can confirm these measurements.
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