Review: 3DM Öhlins R&T kit + TMS camber plates + Syncro Design Works tension arms

[Obioban]

Plan for the future: more bump travel.

Reasons:

1. Just hit the bump stops for the 3rd time since the install today. Horrible bumps -- far from the norm -- but if I can solve it, why not?
2. Calculations suggest I don't have much bump travel right now, and a ton of room to trade droop travel for it

I haven't taken any measurements; just calculated. Given:

- 343 lbs/in spring rate
- ~5 mm preload*
- 0.96 spring motion ratio
- 113 mm total damper stroke travel
- 25 mm bump stop length, of which 20 mm is usable*
- 880 lbs sprung corner weight

* = per Barry @ 3DM

Spring rate comes out to 343 / 25.4 = 13.5 lbs/mm.

880 [sprung corner weight] / 13.5 [spring rate] / .96 [motion ratio] - 5 [preload] = 62.9 mm suspension compression with car on the ground

113 - 25 = 88 mm damper stroke until bump stop engagement
113 - 5 = 108 mm total available damper stroke

So, roughly 25 mm damper stroke from rest until bump stop engagement, or 45 mm available damper stroke until things in the cabin get painful. Does that make sense?

343*.96 = 329 lb/in wheel rate
880/329 = 2.67" compression = 68mm. 5mm of that is preload, so 63mm of droop = exactly what you said.

So 45mm of bump travel, of which 20mm you're in the bump stop. Sounds like more bump travel would be good!

... I'd measure droop before doing anything, to verify.

[IamFODI]

Curious what happened next...

At some point after the post you're responding to, I decided to lower the front just a smidge to ZCP height (rear was already there) and, while I was already messing with it, took the opportunity to trade some droop for 4-5 mm more bump up front. If that made a difference at all, it was minor.

I also sustained a few more bump stop hits on awful roads (not sure there's any other kind around here any more) and noticed zero ill effects other than the obvious unpleasantness. It's alarmingly loud when it happens, which in retrospect was probably my whole reason for wanting to change suspension settings to mitigate it. But then I realized my monoball camber plates and FTABs were probably making those hits sound much worse. Maybe I was overestimating how bad the impacts really were for the car.

Lastly, I'm not sure it's possible to achieve a bunch more bump travel without sacrificing too much droop. It seems like the only real way to solve the problem is with significantly longer damper bodies, which would basically require re-engineering the kit -- something I was trying to avoid in the first place.

On balance, if the only issue is very rare and brief moments of unpleasantness -- a lot of which will go away once the roads are finally re-paved -- that doesn't feel to me like enough reason on its own to dig further into this when I can't be fairly sure that the end result will be better overall.

I'm unhappy with my ride quality and my gut is the front is oversprung (8k(448lbin) which is mild by some but my understanding is stock ZCP is 3k(167lbin)...but my issue could just as easily be improper pre-load, so I've got some investigation to do.

Moved my response and subsequent discussion to a new thread.

[IamFODI]

Time for some track impressions. 7 trackdays on this setup, all at NJMP (5 at Thunderbolt, 2 at Lightning). Street tires and brakes, zero power mods, novice-to-intermediate pace.

BLUF: Couldn't have asked for anything better.

You can really tell Öhlins developed the basic R&T kit at a track. Everything about its behavior is well controlled. I made my share of mistakes but the car never put a foot wrong.

It rides curbs like an absolute champ. The suspension shrugs off the initial impact, eats up the rumble strips if you hit them, and lets you back on the pavement with zero drama.

Handling is very intuitive and noob-friendly. Understeer is predictable. Oversteer is super progressive. Either condition is eminently correctable. Enough bark, zero bite.

This is definitely a very understeer-biased setup. I'd love a bunch more front end grip and pointier steering response. But I understand I can't do much to get that without massively lightweighting the car or sacrificing some limit friendliness, so I'm not unhappy on this front.

Overall, I would strongly recommend this setup for someone in my shoes (track noob who DDs the car).

[ultimatemj]

This is definitely a very understeer-biased setup. I'd love a bunch more front end grip and pointier steering response. But I understand I can't do much to get that without massively lightweighting the car or sacrificing some limit friendliness

I don't see/recall your tire setup, but Dinan has some info in their suspension kit about how front/rear tire size difference influences turn in...might be something to consider

INSR190-9131Page 14of 16Rev. 4not turn well when going fast.If you drive the car fast,you will punish the front tires so much that they will overheat the compound and actually increase under-steer as the tires get older.
30mm smaller front tires:If you have 30mm smaller front tires than the rear,you will have noticeable under-steer, probably more than desired. This is the typical factory M-car set up, designed to make enough under-steer to keep you out of trouble. If you drive the car fast, you will punish the front tires a little more than the rear, which will overheat the compound and actually increase under-steer slightly as the tires get older. This is the safest combination.
20mm smaller front tires:If you have 20mm smaller front tires than the rear, you can achieve a well balanced car. This is the typical Dinan configuration, designed to make it possible to achieve under-steer or over-steer at will, based on your set up and driving style. If you drive the car fast, you will punish the tires equally, so the car will remain balanced as the tires get older.
10mm smaller front tires:If you have 10mm smaller front tires than the rear,you can achieve a well balanced car. This will make it possible to achieve under-steer or over-steer at will based on your set up and driving style. If you drive the car fast,you will punish the rear tires slightly more than the fronts, and the car will develop a slight over-steer as the tires gets older. This is only true of a high powered car because of its ability to “turn the rear tires over”. A low-powered car will maintain good balance,and the rear tires will not degrade more quickly than the fronts.
Equal sized tires front & rear:If you have equal sized tires front and rear, you can achieve a well balanced car. This will make it possible to attain under-steer or over-steer at will, based on your set up and driving style. You will punish the rear tires a lot more than the fronts, and the car will develop a significant over-steer as the tires get older. This is more true of a high powered car because of the ability to “turn the rear tires over”. It’s OK to install a smaller rear tire to balance the car. Oftentimes people put on a larger rear tire, when a smaller one will actually make the car handle better.

How's the ride quality "around town"? Do you find yourself driving around road imperfections, or does the set up do fine around town?

Thanks

[IamFODI]

I don't see/recall your tire setup, but Dinan has some info in their suspension kit about how front/rear tire size difference influences turn in...might be something to consider

245f/265r PS4S. Definitely thinking about other setups for whenever I'm ready for dedicated track tires.

Saw some chunking on the outer edges of the front tire on my most recent track days, so it seems advisable to run more camber at the track. I'm sure that'll help some.

Street use is a tougher nut to crack. Don't want wider tires because I don't want to reduce hydroplaning resistance (already unhappy on this point -- my last car was better). Don't want more camber for wear reasons. But understeer is much less of a problem on the street anyway, for obvious reasons.

How's the ride quality "around town"? Do you find yourself driving around road imperfections, or does the set up do fine around town?

Overall, I feel about the same now as I did when I wrote my initial impressions of ride quality.

The only road imperfections I avoid are the absolute biggest bumps/potholes (bump stop hits are extra loud with this setup). Everything else is a non-issue for me. It doesn't have the eerie smoothness and composure of a modern sport/luxury car, but it's good enough that I can just drive and not worry about the condition of the pavement.

[IamFODI]

The only road imperfections I avoid are the absolute biggest bumps/potholes (bump stop hits are extra loud with this setup). Everything else is a non-issue for me. It doesn't have the eerie smoothness and composure of a modern sport/luxury car, but it's good enough that I can just drive and not worry about the condition of the pavement.

This comment hasn't aged well.

The roads around where I live have been horrendous this winter. Worse than normal. Big dips and heaves, major potholes, and some very broken pavement everywhere. That means a really busy ride, lots of impact noises, and frequent worries about running out of bump travel.

Not that the stock setup was much fun on roads like this, either. But at least it didn't constantly threaten a huge "BANG" where most cars would only make a mildly disconcerting "thump."

So I guess, if your roads are in a state of hideous state of neglect, don't buy travel-limited coilovers or replace all the rubber in your front suspension with sphericals. 😛

[ultimatemj]

Well, I decided to make the switch to the Ohlins....install next week!

Curious, how many clicks are you running the dampers, front and rear?

[IamFODI]

Well, I decided to make the switch to the Ohlins....install next week!

Curious, how many clicks are you running the dampers, front and rear?

Nice. Interested to read your impressions.

I ended up 5 clicks from the firmest setting all around. Based on forum posts, other people have chosen very different settings, so I'd strongly recommend trying things yourself. IMO the most important thing about the setting is how you arrive at it. Here's the procedure I posted in another thread:

Start at the softest setting and drive around. Pay attention for whether the car flops around or bounces more than you'd like. If it does, dial the damping up one click. Repeat until you find the setting you like.

At some point, you might realize that increasing damping doesn't make the car feel better. If that happens, come back down to the softest setting before things stopped improving. E.g., if anything past 6 doesn't help, keep it at 6. I pulled that number out of thin air but you get the point.

Ideally, this should be done one axle at a time. I.e. see whether the front or rear is the source of the excess motion and tweak only that axle -- or try each individually before clicking all of them up. The former requires you to be a lot more sensitive and perceptive; the latter takes a lot more time. If you don't want to mess with that, just raise all the settings together.

This applies to any adjustable damper. Other people's preferred settings can be good sanity checks -- e.g. if everyone says 5 and you hate anything besides 10, it might make sense to revisit your perceptions (again, totally made those numbers up but you get the point). However, the reality is that you'll have to do some tweaking no matter what, so IMO you might as well start from scratch.

The reason for starting at full soft is that you want only as much damping as you need, and no more. As much as necessary, but as little as possible.

[Exclusivs]

Obioban Are these ohlin kits still suffering from the lack of travel discovered by and needing to use TMS plates, etc?

[ultimatemj]

Obioban Are these ohlin kits still suffering from the lack of travel discovered by and needing to use TMS plates, etc?

Considering mine are about to be installed, this would be really helpful to know ASAP

Being the design adjust ride height via raising and lowering the body, I'd hope the design has (at least) the stock amount stroke with the 6mm spring preload (indicated in the install manual).

[IamFODI]

Considering mine are about to be installed, this would be really helpful to know ASAP

Being the design adjust ride height via raising and lowering the body, I'd hope the design has (at least) the stock amount stroke with the 6mm spring preload (indicated in the install manual).

Total travel is something like 1.2" less than stock. It's definitely a short damper. But with default settings, most of the loss is in droop. Bump travel is comparable to stock; maybe slightly more if my calculations are right.

There are some asterisks on the bump travel comparison though. The stock bump stop is long; it engages after 0.5" or less of bump travel, and then it has another 1" or so of compression before it runs out of give. The Öhlins kit with out-of-the-box settings has about 1" of bump travel before engaging the bump stop, and then another 0.8" before the bump stop ends.

[ultimatemj]

Wait, the Ohlins don't have 150m of travel?? DOH!
If that's the case, these won't ride much better than the coilovers I'm coming from

[IamFODI]

Well, looks like this thread will need a serious revision soon.

After a bunch more bump stop hits, I finally had enough and reached back out to Barry. He suggested increasing front preload further to gain more bump travel – but then realized that might risk coil bind, so we concluded some measurements are in order.

Got into the wheel wells today to take those measurements. Looks like I'm getting coil bind already:



This is with 9mm of preload on the front springs (slightly more than the kit ships with). Assuming 113mm damper travel and 5mm bump stop length when fully compressed, that means the spring could see up to 117mm of compression in use. Swift's specs for this spring indicate a max travel of 4.6", which calculates out to 116.84mm. So, to put it mildly, there doesn't seem to be any more room to add preload with this spring. Even if I'm misreading those marks on the springs, the calculations suggest there's zero room for error.

The next size up in Swift's catalog is a 203mm long spring with considerably more available travel. Unfortunately, the threaded section of the damper body isn't long enough to easily accommodate it, so I'd have to run something like 22 mm of preload. All-in, the total compression would be only 2mm shy of the spring's max. Better, but not by much.

I scanned the ERS and Hyperco catalogs for a spring with more travel. I found exactly one: a Hyperco that'd yield 3.8 mm of breathing room.

Not sure what I'm going to do at this point. I first need to verify the bump stop specs to make sure I know what I'm working with. Whatever the case, though, I'm going to take this as yet another sign of the risks of messing with a fully engineered kit. If I had just stuck with one of 3DM's top mount options instead of the TMS camber plates, I could run a longer spring without issue. Now I have to worry about potential damage to the strut towers and other things, which I really didn't need in my life.

[Obioban]

I ended up using Eibach's extreme travel line of springs for this reason. They're basically linear rate barrel springs designed for use in coilovers, and have a bit more travel than other options of similar length (and eibach claims the entire travel is useable travel, whereas most spring aren't supposed to be used right to the point of coil bind).

[IamFODI]

I ended up using Eibach's extreme travel line of springs for this reason. They're basically linear rate barrel springs designed for use in coilovers, and have a bit more travel than other options of similar length (and eibach claims the entire travel is useable travel, whereas most spring aren't supposed to be used right to the point of coil bind).

Thanks. I did see that series. Best match looks like 0800.2530.0350, with 131mm travel – 2.8mm less than the Hyperco option I saw (188B0350), and only 1mm more than what it'd see in use. 😕