Rear Toe Help

[Yeineken]

Hello all having some alignment gremlins this week.

Had BMW try and do an alignment after doing a full M3 suspension swap including rear subframe. The main issue according to the Tech is the rear toe not being able to get within spec making the rear ended extremely squirrely.

He aligned it to M3/1M specs.

His best guess is the ECS trailing arms are too short. So I will be measuring them and comparing to the OEM trailing arms in a few days. Another solution would be to use adjustable toe arms from Dinan or HPA; however I'm not sure if this is just putting a bandaid on a larger underlying issue.

Attached are the alignment specs. Curious what everyone thinks could be wrong.

[Dackelone]

How slammed are you? I bet a lot. Sounds like you need adjustable rear trailing arm links.

[Yeineken]

Originally Posted by Dackelone

How slammed are you? I bet a lot. Sounds like you need adjustable rear trailing arm links.

Actually I measured the ride height to be pretty close to the 1Ms ride height. It's low but not slammed. Guess I'll look into adjustable toe arms.

[Esteban]

Originally Posted by Yeineken

Actually I measured the ride height to be pretty close to the 1Ms ride height. It's low but not slammed. Guess I'll look into adjustable toe arms.

Doesn't look too low to me...

I like it just the way it is!

PS - those red numbers, though. lol

[MightyMouseTech]

That is a LOT of toe out in the rear. I would think it would be barely drivable. If you reduce the rear camber, it would be closer. Basically, what you want is to set the toe adjusters to maximum, then turn down the rear camber until the toe comes into spec. Basically backwards to doing a normal alignment. You won't have much camber, but at least it will be driveable. Your rear tires will be done in no time as it sits.

Then go find some shorter arms.

[Yeineken]

Yea the car is very sketchy to drive. Unfortunately my DIY alignment was very stable compared to how it is now.

[low135]

Was it a new subframe? I had this problem on a previous car when buying a used subframe. Never could get it correct

[chris_flies]

Did you also swap rear knuckles?

[Yeineken]

Originally Posted by low135

Was it a new subframe? I had this problem on a previous car when buying a used subframe. Never could get it correct

I had them inspect the subframe and he said it was fine and was aligned properly.

Originally Posted by chris_flies

Did you also swap rear knuckles?

I did not change the rear knuckles. From my research that isn't necessary. But I may be wrong.

https://www.1addicts.com/forums/show...=748574&page=4


Now that I've had some more time to think about it I really suspect that the rear is just too low for the OEM arms and I need something adjustable as others have stated.

[Dackelone]

You replaced #17 & #13 with the M control arms right>?


I think you will need to replace #10 to adjust the rear toe properly.



There are Manza and Megan rear toe arms out there. Megans runs about twice the price of Manza arms.

I will be also doing the M3/1M rear suspension soon and wonder IF I will need these rear toe arms. ???


https://www.e90post.com/forums/showthread.php?t=1075804

something like this...
http://www.manzousa.com/index.php/bm...-m-models.html




Dackel


PS: Your ride height looks perfect to me. Not slammed at all. HP Autosport has some insight on what parts are needed?

[Yeineken]

@Dackelone yes all arms have been replaced with M and M3 subframe. #10 was replaced with ECS trailing arms. #10 is also the same part across 135is and 1M/M3s. I still need to get it on the lift and make sure the ECS trailing arms are the same length as OEM.

[Yeineken]

Ended up talking to someone at Dinan to check on the range of adjustability on their toe arm (considering this brand) and here's what one of their engineers had to say.

"Yes, lowering the car can “push out” the tire, increasing the track width. But there are several suspension links, and they all work in unison, so the alignment should stay reasonable, even if the car was lowered. That’s what happens thru the normal travel of the suspension.

He replaced the subframe and arms…

The M-Coupe & M3 subframe and arms are different than the non-M subframe & arms. The toe arm mounts on the M-subframe are about an inch(?) more outboard than the non-M subframe. So this means that the M toe link is shorter than the non-M toe link. My notes say the toe link lengths are around:

· non-M toe link = 16.25”
· M toe link = 15”

I wonder if he got the correct subframe and toe links. If he got a non-M subframe, with M toe links (looks correct in the photo), then it will result in a severe toe-out situation. It doesn’t make complete sense though, as this combination should yield a much worse alignment than what he’s showing. Still, I’d double check the part numbers."

Which doesn't help me much considering I know this is a M3 subframe and these are the correct Toe Links. Really itching to get the car on the lift and inspect what's going on this weekend.

Also starting to contemplate this is just a bad alignment job.

my car:


m3:

[Dackelone]

Originally Posted by Yeineken

@Dackelone yes all arms have been replaced with M and M3 subframe. #10 was replaced with ECS trailing arms. #10 is also the same part across 135is and 1M/M3s. I still need to get it on the lift and make sure the ECS trailing arms are the same length as OEM.

What exactly is an ECS trailing arm ?

Is it adjustable like the Manza unit I posted?



Yes, #10 is the same arm used on a M3/1M and a non M car(like a 135i). That is why you need to replace this part with a link(that is adjustable, like Manza or Megan) to bring your rear toe back to factory specs.


Perhaps you should have a second alignment shop take a look at your car. Maybe the first shop just wasn't comfortable working on your hybrid M suspension. ?

Dack

[Yeineken]

Originally Posted by Dackelone

What exactly is an ECS trailing arm ?

Is it adjustable like the Manza unit I posted?

Yes, #10 is the same arm used on a M3/1M and a non M car(like a 135i). That is why you need to replace this part with a link(that is adjustable, like Manza or Megan) to bring your rear toe back to factory specs.

Perhaps you should have a second alignment shop take a look at your car. Maybe the first shop just wasn't comfortable working on your hybrid M suspension. ?

Dack

I think we are talking about different parts here. The link you provided above is for the toe, which would replace #13 (Steering arm).

#10 is the trailing arm that is the same across non-m and m.
- ecs trailing arms. https://www.ecstuning.com/b-ecs-part...SABEgJN7PD_BwE which are direct replacements for #10.

[Yeineken]

Bit of an update.

The trailing arms are not the problem. They are the exact same size between stock and ecs. So this leads me to think it is possible that the knuckles between the 1M and 135i are more different than I thought.

For the time being upgraded to the Dinan toe arms and raised the rear slightly with the TCKline adjusters.

Will update again when I get the alignment done.

[Sancs]

Any update?

[Yeineken]

Originally Posted by Sancs

Any update?

Not really. The Dinan toe arms fixed the problem. As to why the OEM M3 arms with M3 rear subframe didn't not work is still up in the air.

[duder13]

Originally Posted by Yeineken

...So this leads me to think it is possible that the knuckles between the 1M and 135i are more different than I thought.

Yeah, that would be my guess, too. I can't think of anything else that would cause the variance.