Treehouse Offset Bushings - caster talk

[Guest]

edit: the downpipes themselves won't fit without modification or special CABs (treehouse) that give you very excessive caster

I don't know if "excessive" is the right word. They are just m3 geometry AFAIK.

they're not e30 m3 geometry. I just put a set on my old 318is two weeks ago, set them next to e30 m3 bushings, they're ~3mm farther offset. I was told repeatedly (even by treehouse) that they were e30 m3 offset though :roll: Doesn't change the fact that I think they're a great product and would recommend them for someone with an e36 5 lug swap.

This is true. I was the one that found this out and showed Bryson. I am worried about the extra caster these will provide. To much caster can create a large weight shifts at the corners which can lead to odd handling. I have not yet figured out how much extra caster 3mm will provide over stock offset bushings, and I am sure it isn't too much said and done -- besides, car rake also effects camber -- and to those with adjustable camber and caster plates, this isn't really a worry.

I just wanted to point this out to fellow E30ers.

I haven't had a chance yet to install these bushings, but I plan to do so and put my car on cornerweighting scales to watch the amount of cross-weight movement.

In another point, I am sure the factory offset geometry bushings move a few MM during heavy cornering, accel, and braking anyway -- they are just soft rubber, so this all might be a moot point.

This is an interesting read about stock caster and excessive (if it even is!) caster.

http://www.ground-control.com/?D=51f2dd6e82fbe390283249c1a2ca81d8

[Skafrog]

What is the factory caster degree of an e30 m3?
My car has 9.0 degrees caster with the Treehouse CAB's.
I have the print out if anyone wants to see.

[Digitalwave]

So are you saying that any added castor with these is just as bad as with any E30 M3 offset CAB's? Or are THR's not direct copies, offset wise?

[Stu]

The tolerence range for E30 M3 castor is 8.63 to 9.63 degrees....9.13 being ideal.

[Skafrog]

alright. Here is the pic of mine with the Treehouse CAB's.

There ya go. 8.8 and 9.2. This is certainly because of a bent control arm, what have you. However, the point is: The offset is the same.

[Bryson]

physical comparison and measuring leads me to believe otherwise

I suppose both my eyes and Trent's decieve us ;)

We've compared two sets of these against e30 M3 bushings

[Digitalwave]

physical comparison and measuring leads me to believe otherwise

I suppose both my eyes and Trent's decieve us ;)

We've compared two sets of these against e30 M3 bushings

So they are visually different?

[Skafrog]

physical comparison and measuring leads me to believe otherwise

I suppose both my eyes and Trent's decieve us ;)

We've compared two sets of these against e30 M3 bushings

Well, I will definately take your advice as opposed to cold hard tech as posted above.

[trent]

physical comparison and measuring leads me to believe otherwise

I suppose both my eyes and Trent's decieve us ;)

We've compared two sets of these against e30 M3 bushings

Well, I will definately take your advice as opposed to cold hard tech as posted above.

Hey man...relax....I was just pointing out something visually and I even said why I wasn't that worried about it.

Caster is dependent on ride height. A car that has a rake will have less castor. I remember on my old '89 with the offset E30 M3 bushings I had 7-8deg (can't recall exactly), which is about a degree less than what you showed. I would post the alignment but this was years ago.

[trent]

physical comparison and measuring leads me to believe otherwise

I suppose both my eyes and Trent's decieve us ;)

We've compared two sets of these against e30 M3 bushings

So they are visually different?

Visually, yes. I will take a picture tommorow.

[Skafrog]

physical comparison and measuring leads me to believe otherwise

I suppose both my eyes and Trent's decieve us ;)

We've compared two sets of these against e30 M3 bushings

Well, I will definately take your advice as opposed to cold hard tech as posted above.

Hey man...relax....I was just pointing out something visually and I even said why I wasn't that worried about it.

Caster is dependent on ride height. A car that has a rake will have less castor. I remember on my old '89 with the offset E30 M3 bushings I had 7-8deg (can't recall exactly), which is about a degree less than what you showed. I would post the alignment but this was years ago.

Hey man, I am cool like fonzie. In fact, to drape off your guys' nutsacks, you two are one of maybe 10 that I actually take with more than a grain of salt.
Post some pics up.
FWIW, another manufactuers delrin bushing I was comparing to the stock m3 bushing did not line up. It was maybe 1-2mm outboard of the stock hole.
When you install the m3 CAB's, they might deflect enough to compensate for the differences. Measure the distances with the stock CAB's on and off the car.

[trent]

Hey man, I am cool like fonzie. In fact, to drape off your guys' nutsacks, you two are one of maybe 10 that I actually take with more than a grain of salt.
Post some pics up.
FWIW, another manufactuers delrin bushing I was comparing to the stock m3 bushing did not line up. It was maybe 1-2mm outboard of the stock hole.
When you install the m3 CAB's, they might deflect enough to compensate for the differences. Measure the distances with the stock CAB's on and off the car.

I wouldn't be surprized if another manufactures bushings didn't line up, there are a lot of shitball parts. When I had my offset bushings installed they were prefect (as to where I don't think it would cuase a discrepency, but either way, say they are slightly off 1mm. That means we are at a 2mm offset "difference." I highly doubt frame rails on these old cars are within that close of spec, so this entire topic is a moot point anyway now that I think about it :)

With all this said anyway, I can't wait to install these. :) I just have to finish my heim-jointed tie rod bump steer setup first :)

[Skafrog]

With all this said anyway, I can't wait to install these. :) I just have to finish my heim-jointed tie rod bump steer setup first :)

You might be the first to use the warranty on the bushing material :)

[trent]

With all this said anyway, I can't wait to install these. :) I just have to finish my heim-jointed tie rod bump steer setup first :)

You might be the first to use the warranty on the bushing material :)

fuck man, don't say that! I sure as hell hope not!



I centered the holes with a large bolt then held it and took a pic. Pic actually makes it look more offset. Pic isn't prefect, centering isn't perfect, can't measure on car right now, just an observation. :)

[JasonH]

If the THR bushings cause "excessive" caster on a stock E30 suspension, then what is happening to the suspension geometry when using these bushing with E36 suspension parts? Obviously the result is (ideally) a centered wheel, but you also end up with a control arm that is no longer near its original location. Maybe some of the race engineers on this board can discuss how this might affect the suspension geometry for those going to 5-lug. This may not be much a problem for street use, but it must be having a negative effect on the track.