Stock Endlinks OK for Tracking?
 

Hi Guys,

*noob warning* :slap:

I was checking out the Perrin Polyurethane end links and I noticed in the description that they said something about the stock end links having a flaw.

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I quote from Perrins website:

"Subaru's rear suspension has a flaw. Under certain driving conditions your endlinks can change position and flip under your control arms. This causes major damage to the suspension and of course the endlinks. I highly recommend installing sway bars, stout mounts and endlinks all at the same time"

http://perrinperformance.com/i-14754...-fr-s-brz.html
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My current setup is 18x9.5s /w 245/35/18s. Stock suspension with Racecomp yellows. The mechanic that did work on my car said my wheels were too big for my suspension.

I'm planning to track this setup next month. I was wondering if the end links are at jeopardy with with my meatier tires?

(I do plan on getting coil overs, sway bars, and end links but I my schedule is tight from work and will probably do that when I revisit EFI for an open source retune in a few months...)

Thank you in advance! :cheers:

We have put 30k miles on our BRZ going to nearly every single track day every weekend in the past year and hold most of the FRS/BRZ street tire (and perhaps R-comp) records with very minimal modifications. I think you will be fine. :thumbup:

Tracked mine several times with RCE springs and sways and stock endlinks with 235/35/18 grippy street tires; no issues.

The main reason to swap endlinks is to eliminate pre-load. The stock endlinks are not adjustable. So if you are lowering the car you are creating more pre-load on the bar.

The real world effects of this for most people are minimal but will cause more wear on the bushing of the endlinks.

For track guys, the truth is it can effect handling but with so much slop in the suspension as it stands its not as noticable there either. If you were setting up a hardened track car I would have adjustable endlinks front and rear to do a proper setup.

Thanks guys, I appreciate the feedback.

I do plan on changing out the bushings when I change out the end links, sway bars, and stock dampers (obviously) so I am not worried about them wearing out.

Change of plans though, probably going to go with Koni dampers instead of coil overs. My friend who is guiding me with my modifications told me that coil overs are probably too advanced for my needs.

Setting up an adjustable suspension properly is a time sink and very few people spend the time to do it right.

I am pretty OCD about things being set up properly so it is probably for the best that I go with a "one size fits all" kind of deal via the dampers.

Next hurdle.. sway bars and what gauge to go with... *rips hair out* Luckily I have at least a month or two to research and decide.

What is your intended goal? Sway bars are a fine tuning item. They may reduce roll, but it ultimately makes small differences compared to other items.

:offtopic: <---- but with a smiley face!! :thumbup:

My BRZ is my weekend car / occasional track car when I can do track days. I hope to be able to do at least 3 and hopefully 5 or 6 track days next year.

I just want improved handling, I don't mind a little over steer but want to avoid under steer. (I think that makes sense?) I'm sure we all want "improved handling" so I guess that might be a little too general. I don't plan on turning this into a drift car or a drag car. Just want as much nimbleness as I can get out of her without sacrificing stability.

I plan on doing at least one track day with the stock sway bars / end links before I decide so I actually have a good idea of the cornering characteristics of the BRZ which I wouldn't be able to feel out on the street.

My main question regarding this is which gauge of sway bar and also what combination for the front and rear. I currently am thinking the 19 front / 16 rears from Perrin. With Kartboy end links. But I would be open to Whiteline sway bars as well.

This can turn into a long convo. I'll PM you. :)

Could you elaborate on this? I don't understand how lowering the vehicle could pre-load the bar.

Basically lowering the suspension or bringing lower control arms upward toward the frame simulate a loaded ARB because the links are a fixed length designed for stock height.

Moving the control arms up load the bar. This can effect corner balancing and track setups/shock setup. Ideally you want to change the end links to threaded units to be able to set the bar to neutral. So the bar is not pre-loaded.

Nope, I still don't get it. I thought arb only have an effect when they are being twisted. When both side are moving up or down in unison there is no effect. I appreciate that altering the end link lengths changes the geometry but I don't see how this "pre-loads" the arb. That is, if one loosens the end links on one side the arb doesn't spring back into a different position; the sway bar is not storing any energy.

^^ This.

There's no pre-load on the sway bars, if both wheels are moving up and down together the bar adds almost zero resistance (other than any resistance in the bushing). If you don't believe it, disconnect the end links and see how easy it is to rotate the bar.

The bigger reason for shorter end links (especially up front) is that the stock ones can end up binding when lowered too much.

There is something to be said about shortening the links so that the bar is in the same position as stock to keep the geometry closer to stock, but it's not going to harm the bar to not get adjustable links.

As I said for a street car its not going to make a huge difference. But when you have a preloaded bar it changes the forces required to twist. A preloaded bar requires more force to twist. Also this as mentioned can effect your setup but also can be used to change corner balance. Importantly it can effectively change spring shock settings because of the forces requires to twist the bar. An ARB is a spring you preload it and it can increase its effective rate which changes things underload and vice versa.

I spent a few weekends in a race shop dealing with all of this. Makes your head explode.

Go to 4:25

[ame="https://www.youtube.com/watch?v=wvHH_Aoz-RU&feature=youtube_gdata_player"]Alignment 949 Racing Supermiata - YouTube[/ame]

When he says pre-load, I don't think he means storing energy in the bar. What I see happening is that as the car is lowered and the sway bar arms rotate up, you shorten the moment arm that you have to twist the bar, effectively stiffening it.

edit - depending on the starting angle of the sway bar arms it could either become stiffer or softer with lowered ride height.

I think pre-load is a really bad word to describe this, there is no load on the bar at all. All that changes is the lever length (kinda) as the bar rotates up from horizontal.

The real thing to look out for is if you're lowered to the point that any further compression travel actually puts the bar 90* from stock, if you continue to compress the suspension you'll have to bend the bar (not twist, bend) to get any more travel.

That said, I'm sure that unless you're lowered 3" and have lots of compression travel and soft springs you'll be totally fine.

God... This is getting more complex as we continue. Thanks for the explanation. I'm starting to get it

The end links should be close to neutral (No Load) when the car suspension is uncompressed.

Load on the bar in with suspension uncompressed is pre-load.
Nothing else to call it.

Lowering the vehicle pulls the lower control arms up toward the shock/strut towers. With the end links at a factory length you now have pre-load on the bar.

If you take a lowered car with stock endlinks, put the car on scales, disconnect one of the endlinks and the corner balance changes, the endlinks had pre-load. That's exactly what we saw.

But again, this is not a race car and the suspension setup I used was valved and sprung around the stock bars.
@Racecomp Engineering

^^ How much was that car lowered though? The only way that would come into play is if it's so low that at resting height it's binding from the bar being rotated too far or if something is a bit twisted or leaning (not ride height related at all). Was the car sitting level side to side before disconnecting the bar, or was one side slightly lower? Any load on the bar from unequal suspension movement (leaning, etc) shouldn't be confused with load on the bar from lowering evenly. I bet if you put a stock car on scales with the driver in it you would find both front and rear bars have a bit of pre-load on them as well.

I just watched parts of the video again (the part talking about pre-load), and I think you're mixing things up... the pre-load mentioned there would be from one link being longer or shorter than the other, not both being too short or too long.

To get it right (with adjustable links) you would disconnect one, then adjust the other so that at resting ride height the bar is horizontal. Then go to the other side and adjust the length so that there's no pre-load on the bar side to side. You should start with the links at the same length, but there's no guarantee their happy length will be identical to each other.

The key to all this (with corner balancing) is that you don't want to be fighting the bars, so you set the car up with the bar disconnected, then when you go to reconnect the bar you adjust the links so that there's no twisting load on the bar at resting height. Nothing to do with the final ride height, just correcting for different heights across an axle. Getting even weight distribution might not result in the same ride height at both wheels, and that would add some twist load to the bar.

Don't believe me, go disconnect both end links and see how much load you can get on the bar by rotating it, the answer is next to none.

The truth is the original post asked about stock endlinks being ok for track use. And with a nominal amount of lowering won't cause any issues.

All I was saying is changing the the stock suspension geometry puts more pre-load on the sway bar. This has an effect on valving and spring rates as it increased the load required to twist the ARB. Like I said I saw this by by removing the end links and also on the scales. Already with driver weight.

You are arguing that the bar will just move upward and there will always be some twist but with both links connected, its very minimal. Where you see more action is the deflecting of the end link bushings which it does until those pivot joints max out under high load.

If you really watch the video the sway bar is perfectly horizontal, but they still have to disconnect the one end link to do the corner weighting, so that takes away any of the pre-load you're talking about from lowering and only leaves the pre-load from differing ride heights.

Like I said above, even at stock height you would have to disconnect one end link per bar to properly corner weight the car.

I still 100% disagree with what you're calling pre-load since it isn't adding any tension to the bar at all. Load implies adding tension or force.