Ohlins Coilover Setup

[Imperial]

The spring bucket/toe arm adjusts toe, the traction arm alters the travel arc of the hub, effectively pulling it in, during compression aiding rear wheel traction hence "traction arm".

 

[OptionZero]

Assuming I leave the mid-link (spring bucket) stock, toe is adjusted with the bucket eccentric?...and/or the traction arm? Not sure how the traction arm plays in...something about bump steer, which I think is toe-related.

Alignment pro's know what's needed, but I'd like to know for my own benefit. Searching isn't answering my questions. Or it does, then the next thing I read contradicts some of it.

As Imperial explained, when referring to individual components, "link" and "arm" are the same. It's the piece of metal that connects two points.

The "billet" version of SPL arms are the heavier duty version of the dogbone style. As you can, see they have a boxed shape with reinforcing braces that form triangles. The two versions do the same thing, one is for those that need to withstand greater stress (pure track car).

With the SPL mid-link, toe is adjusted by changing the length of this arm via the adjustable end that has a thread and locking assembly. Not changing this arm mean you don't get that length adjustment and are left only with the factory eccentric bolt to adjust toe

Although it requires changing to a 60mm OD spring, it is worth it to get that adjustment. One less rubber bushing to fail.

The eccentric lockout kit replaces the factory eccentric bolts with non moving bolts that are locked in place. With adjustment at arm, the factory eccentric bolt becomes a failure point. Even under stock conditions and ordinary use, there can be some slippage over time, which changes your alignment. The degree to which this occurs depends on the age of the car and how it is used. The lockout kit eliminates this possibility. Aftermarket eccentric bolts that offer added adjustment usually require cutting of the subframe area.

As for the traction arm, this may be difficult to explain. The three arms (Camber, midlink or toe, and traction) form a triangle. When your suspension tech changes the length of one to adjust, say, camber, it changes the relationship of that arm to the others. This may do nothing in static conditions when only a little bit is changed; however, when you change one alot, or change two out of three arms' length, it may affect:

1) How the wheel sits within the wheel well. On my IS300, adding negative camber pulled the wheel forward within the wheel well. At the time, I did not have multiple adjustment arms so changing one arm messed up with positioning. Adding more adjustment points allowed the tech to fix this.

2) More importantly, the three arms affect each other's movement arcs when the car is in motion and the suspension has to do work. This is where the reference to bump steer comes from. Again, think of a triangle, except all three corners also are joints that move up and down. They are all tugging at each other in a sense. Changing the length of one affects how the others move.

Rear bumpsteer is "unwanted toe changes when a car encounters a bump and compression." In other words, the car will feel and act jittery



TL;DR:
Get all the arms, they affect each other, mostly under load. The only drawback is cost and changing the diameter of a divorced spring. 60MM OD is a common size, you can get the same rate you otherwise would have. SakeBomb can get it for you from Swift, Hyperco, or Eibach.

 

[FSUZ33]

My kit will have Swifts. Will that be 60mm, or would that be a special request?

Thank you both for helping me through this!

 

[OptionZero]

My kit will have Swifts. Will that be 60mm, or would that be a special request?

Thank you both for helping me through this!

For use with the SPL mid link it is 60mm inner diameter. I misspoke earlier and wrote outter diameter.
Check:
https://www.splparts.com/products/370z-g37-rear-mid-links.html

For use with OEM buckets, i dunno, theyre huge. For example i found an old pic of the springs for my Aragostas

 

[Imperial]

My kit will have Swifts. Will that be 60mm, or would that be a special request?

Thank you both for helping me through this!

Only your retailer will be able to tell you what size spring they've decided to use for your kit. Ohlins Japan uses OE size springs so I will be keeping my spring bucket.

 

[OptionZero]

Only your retailer will be able to tell you what size spring they've decided to use for your kit. Ohlins Japan uses OE size springs so I will be keeping my spring bucket.

if they’re divorced and being assembled for a custom app it should be easy to provide the requested diameter

 

[Imperial]

if they’re divorced and being assembled for a custom app it should be easy to provide the requested diameter

I agree; these details should have been apparent at the point of purchase. If they're truly a bespoke application, then I have a feeling they would select a more readily available industry standard spring size versus having something wound up to OE specifications.

 

[FSUZ33]

With these coilovers I feel like I just bought a car with an MT and dont know how to drive a stick (although that I DO know). Coils should arrive soon. Nick, I think, at Sakebomb said they were ready this weekend. Have an abdominal surgery coming up and I’m not going to be able to get them installed before that, and probably a couple of months before I can wrench on my car, so I’ve got some time to plan and buy crap I need. Also planning to get some thrust bearings if they don’t have them already. Looking at QA1 bearings from Summit. Look like the exact same ones you can get from McMaster. 2.5” ID and about 1/8” thick with the bearing and a washer/race on each side, but a little cheaper from Summit. assume the best placement for the fronts is on top of the main spring and below the helper.

 

[Imperial]

My set is getting installed as we speak.​

 

[Imperial]

My new stance at Ohlins specifications.

 

[Imperial]

Beauties…

 

[Murix]

how do you adjust the rear? Remote extenders?

 

[Imperial]

how do you adjust the rear? Remote extenders?

Correct.

 

[dport]

Very nice. What rotors are those?

 

[Imperial]

Very nice. What rotors are those?

Racing Brake