SPL Rear Trailing Arms Anyone?

[hellokitty]

I am considering upgrading the rear trailing arm to help with keeping the rear end in check. The tail gets too happy even with running on E35 these days and I am hoping this will solve the issue for good.

https://www.bimmerworld.com/SPL-Race...-M2-M3-M4.html

I am also upgrading to SPL Toe Arms w/lockout as part of this upgrade,

Anyone run both or do you guys think the toe arm is all that is needed?

Any thoughts are appreciated!

I am trying not to go "all-in" with SPL parts. I just want to dial it in with as little as possible to solve the rear end issue. I've been down the rabbit hole before with going all out on suspension arms in previous generation BMW cars... no desire to do it again lol

[fanatic1]

Originally Posted by hellokitty

I am considering upgrading the rear trailing arm to help with keeping the rear end in check. The tail gets too happy even with running on E35 these days and I am hoping this will solve the issue for good.

https://www.bimmerworld.com/SPL-Race...-M2-M3-M4.html

I am also upgrading to SPL Toe Arms w/lockout as part of this upgrade,

Anyone run both or do you guys think the toe arm is all that is needed?

Any thoughts are appreciated!

I am trying not to go "all-in" with SPL parts. I just want to dial it in with as little as possible to solve the rear end issue. I've been down the rabbit hole before with going all out on suspension arms in previous generation BMW cars... no desire to do it again lol

I did consider same as you, but went just the fall line toe links - and eccentric lockouts for both camber and toe.

Helped dramatically and primary issue was once you lower the car on coils, it's hard to get the appropriate toe in with stock toe links. Also removing eccentric stopped alignment "drift", prior every time on the alignment rack was different.

This combined with the front tension arm bushing dramatically stabilized the car.

[hellokitty]

Originally Posted by fanatic1

I did consider same as you, but went just the fall line toe links - and eccentric lockouts for both camber and toe.

Helped dramatically and primary issue was once you lower the car on coils, it's hard to get the appropriate toe in with stock toe links. Also removing eccentric stopped alignment "drift", prior every time on the alignment rack was different.

This combined with the front tension arm bushing dramatically stabilized the car.

Are you talking about the front mono balls? Which brand did you go with?

Thanks for your insight

https://www.splparts.com/products/bm...-bushings.html

[1000hp]

Originally Posted by fanatic1

I did consider same as you, but went just the fall line toe links - and eccentric lockouts for both camber and toe.

Helped dramatically and primary issue was once you lower the car on coils, it's hard to get the appropriate toe in with stock toe links. Also removing eccentric stopped alignment "drift", prior every time on the alignment rack was different.

This combined with the front tension arm bushing dramatically stabilized the car.

Have you had any issues with yours? Just read a thread about a failure with one of these links.

[hellokitty]

Originally Posted by 1000hp

Have you had any issues with yours? Just read a thread about a failure with one of these links.

I'll let you know if I have any issues with my setup.

I just bought all of the SPL arms front and back based on the advice of my alignment tech.

I tried to hone in on only ordering the arms I need based on the issues we are trying to address. However, at the end of the day, everything works together so it was best to either go all or nothing. This way, we can adjust for the entire suspension geometry without any limitations.

[hellokitty]

Another thing to note, one thing I noticed with SPL arms is that they are VERY light.

I ordered a part from SPL and another one from ECS Tuning (both arms), and the SPL is literally half the weight of the ECS one.

I think this is why SPL is more expensive.

[1000hp]

Originally Posted by hellokitty

I'll let you know if I have any issues with my setup.

I just bought all of the SPL arms front and back based on the advice of my alignment tech.

I tried to hone in on only ordering the arms I need based on the issues we are trying to address. However, at the end of the day, everything works together so it was best to either go all or nothing. This way, we can adjust for the entire suspension geometry without any limitations.

I'm waiting to hear back from the guy whose Fall Line arms failed, as those are the ones that are available with booted rod ends, and I have had exposed heim joint rod ends fail rapidly on other cars.

If I do them, I will probably at least replace the toe adjustment links and the rear thrust links (or whatever BMW calls them) which are the exact same part as the toe link except without the eccentric washers.

[hellokitty]

Originally Posted by 1000hp

I'm waiting to hear back from the guy whose Fall Line arms failed, as those are the ones that are available with booted rod ends, and I have had exposed heim joint rod ends fail rapidly on other cars.

If I do them, I will probably at least replace the toe adjustment links and the rear thrust links (or whatever BMW calls them) which are the exact same part as the toe link except without the eccentric washers.

I think the bare minimum would be front tension arms since this replaces the entire arm rather than doing the monoball like most people do and Rear toe links with lockout.

Probably best bang for your buck is those 2 sets of arms.

I had to do everything in the rear so we can dial in more positive camber so I get better traction on E85.

[1000hp]

Originally Posted by hellokitty

I think the bare minimum would be front tension arms since this replaces the entire arm rather than doing the monoball like most people do and Rear toe links with lockout.

Probably best bang for your buck is those 2 sets of arms.

I had to do everything in the rear so we can dial in more positive camber so I get better traction on E85.

I've been happy with the front grip so far, with monoball tension bushings.

The rear can be a little squirrelly under power if the road is not perfectly flat, and not for loss of traction. I can clearly feel the toe moving around back there under those circumstances. It's more pronounced when the rear tires don't break loose. I plan to start with the toe links and the rear (of the car) thrust links.

[hellokitty]

Originally Posted by 1000hp

I've been happy with the front grip so far, with monoball tension bushings.

The rear can be a little squirrelly under power if the road is not perfectly flat, and not for loss of traction. I can clearly feel the toe moving around back there under those circumstances. It's more pronounced when the rear tires don't break loose. I plan to start with the toe links and the rear (of the car) thrust links.

If you already have monoballs then no need to upgrade the arm up front.

The SPL front arm is only needed when you don't have monoballs already and want to swap the factory arm with the SPL arm.

SPL arm allows adjustment of caster plus allows the benefit of a solid bushing

[1000hp]

I'm talking about the rear suspension.

There are toe links available from SPL, Fall Line, and others with heim joint rod ends.
There is another link in the rear (what I'm referring to as a "rear thrust arm" for lack of a better term) that uses the same link, but without adjustment.

The part circled in the parts diagram is the other link that I'm referring to, which uses the same part as the toe adjustment link.

[sly1types]

I have the SPL rear toe links with lockouts and they well crafted and you can notice the difference. It made my car feel like the whole chassis turns in now.

[1000hp]

Originally Posted by sly1types

I have the SPL rear toe links with lockouts and they well crafted and you can notice the difference. It made my car feel like the whole chassis turns in now.

Good to know. Thanks!

[fanatic1]

Originally Posted by 1000hp

Have you had any issues with yours? Just read a thread about a failure with one of these links.

I did have issues with mine, but I'm pretty sure it's an outlier. The track version of the urethane thrust arm bushing is what I used.

No reason not to go full metal jacket here with mono ball

[1000hp]

Originally Posted by fanatic1

I did have issues with mine, but I'm pretty sure it's an outlier. The track version of the urethane thrust arm bushing is what I used.

No reason not to go full metal jacket here with mono ball

I was referring to issues with the rear toe links. I'm wondering how long the rod ends will last.
I have turner monoballs up front and have had no issues with them.

[fanatic1]

Originally Posted by 1000hp

I was referring to issues with the rear toe links. I'm wondering how long the rod ends will last.
I have turner monoballs up front and have had no issues with them.

No issues on the rear toe links

[1000hp]

Originally Posted by fanatic1

No issues on the rear toe links

Cool. Thanks.

[hellokitty]

Just wanted to give my impressions on the full SPL kit.

- No NVH to be had other than a heavier steering wheel in comfort and more road feel in the steering wheel. It feels like hydraulic steering. Very positive feeling. Comfort mode feels like Sport mode now.

- Bump steer completely eliminated

- No weird noses or or clunks

- Very solid going into corners. The car is very very precise and doesn't lose any composure at high speed / cornering.

- Rear end has been slop is completely gone. I would recommend the rear end kit to anyone running stage 2 on full E85. You'll be able to put the power down without fear of losing the rear end.

This is a major upgrade ($$$$) and not for the faint of heart unless you are a total track junkie or adding a lot of power to the point where the car loses composure.

[1000hp]

Originally Posted by hellokitty

It feels like hydraulic steering.

Sold!
Which parts do you think achieved this for you?

[hellokitty]

Originally Posted by 1000hp

Sold!
Which parts do you think achieved this for you?

Most likely the tension arm but I'm sure the lower control arm helps too. The tension arm is a better solution compared to pushing a monoball into the stock arm.

https://www.splparts.com/products/bm...sion-rods.html

https://www.splparts.com/products/bm...-m2-m3-m4.html

[heitzke]

Appreciate the review on this too. I've been contemplating a few of the components for the rear just to help with street traction. It seems like maybe just the rear traction arm and the toe arm would help with this?

There's a terminology distinction that confuses me though. The Dinan rear kit specifies the rear toe arm and the rear trailing arm. The real trailing arm is what the SPL kit calls the traction arm? Or am I missing something else?

[hellokitty]

Yes, there are 4 total arms on each side in the rear.

2 camber arms
1 toe link
1 traction arm aka trailing arm