Adjustable Toe and binding Reduction: Stage 2 Measure/Calcs

Re: Adjustable Toe and binding Reduction: Stage 1 Planning

When our cars are slammed in addition to the rear wheels gaining toe in the wheel also moves forward in the wheel well.

If toe adjustment is made on the inner mount it will need to be shortened to straighten out toe, but the wheel will still be further forward in the wheel well.

Instead, consider making your toe adjustment on the outboard heim by extending it's length, pushing the wheel back to the center of the wheel well while also reducing toe in.

End result being the inner mount is a heim to reduce binding, the outer mount is a heim to extend the length of the control arm, reducing toe, returning the wheel to the center of the wheel arch, and also having some sort of camber adjustment.

Yes, I've thought about doing this for a while, lol.

Re: Adjustable Toe and binding Reduction: Stage 1 Planning

^exactly. The main problem still remains though, toe/camber gain on our low cars is unbearable.

Re: Rear Control Arm Camber and Toe Bolt Diameter

[quote]nismopu wrote: [quote=adamvann3]I can think of at least 3 ways to do what he did better.

Re: Adjustable Toe and binding Reduction: Stage 1 Planning

With my tire/fender clearance I have 1" suspension travel. Removing that from the situation, with 12k's I might have 2" travel. How much camber/toe gain can be seen at 1" and 2" travel assuming the starting point is zero toe/camber?

I feel like at my ride height the camber gains seen during 1" of travel are greater than what would be seen on a stock car raised high enough to have zero toe/camber. But that's just an eyeballing guestimation.

Re: Adjustable Toe and binding Reduction: Stage 1 Planning

[quote]Benedict wrote: A lot on a low car. Not much on a car with stock ride height. There are ways to measure, caveman method tapes a marker to the hub and have it draw on pc of cardboard as you stroke the suspension through its travel.

Re: Adjustable Toe and binding Reduction: Stage 1 Planning

Here is one of the articles that sparked my interest in the matter: http://www.e30m3project.com/e30m3perfor … /index.htm

Just an awesome write up on the matter at hand. In my nights of random suspension reading, I have found the e30 community to be the most informative on the semi trailing arm, and pretty reliant to what the z31 has. Once I nab a rear x-member+CA I will put together some calculations, and graphs more specific to the z31.

For now, here is some general calcs from the above link.





Off hand I dont have the sweep angle for the z31, so for shits and giggles lets assume its the same as the e30's. For a pure trailing arm theta=0 thus no change in camber or toe throughout the suspension travel. Below what you're going to see is the e30 sweep angle=15* along with a modified BMW motorsport e30 m3 touring=12*. The basis of the graph is with the CA at 0* with a full sweep up to 90* (unrealistic, however if you read the article the author later uses realistic inches of travel vs camber gains). When rotation of the arm =90, the sweep angle=camber angle.



more reads later:
Same article goes into the same depth in toe curve, in which you can read.


In the end semi trailing on a lowered car on pavement is not ideal (now for an off road buggy its s different situation). I am not going to argue that. All that I am trying to gain from this is better static alignment numbers, thus allowing be to drive my car without chewing up rear tires driving in a straight line. For race car sake, this is not the best. However if I feel like making the car more competitive I will switch to multi-link (thanks mike for the kits, butter and others for write-ups and research). The semi trailing is more than capable of hard/spirited back road driving in which my car sees a lot of; cost vs benefit

Enjoy!

Re: Adjustable Toe and binding Reduction: Stage 1 Planning

As a suggestion: Before you start buying things and hacking away you might want to map the suspension – at least 3” above and below actual ride height, so that you know for sure where the best possible ride height is.

Say for every ¼” (plus or minus from static) ride height change how much does it change camber and toe? It costs you nothing but time.

For mapping the front you might also map it a 10*, 20* & 30* left and right turns to see if the results are much different that straight ahead. It will also give you and indication of what caster changes, if any, might be helpful.

When you map the rear, you can find a sweet spot that gives you the least toe change in your anticipated operating range and also find the most consistent camber change (which your tires will thank you for). Running at that set up lets my tires run within a couple degrees temperature on the outside, middle and inside. Their happy place!

The two Z31’s that I have mapped ended up having slightly different best ride heights. Also the left and right rear maps will be slightly different – as the rear suspension seems to have been manufactured that way.

As it works out with my current overall set up (coilovers ++ but no adjustable rear cross member yet), I have to run my ride height about 1.5” higher than I would really like to, because it produces the best grip - under all conditions.

At least by mapping you will have a starting point to measure everything else from. Mapping, along with tire temperatures, skid pad timing, and driver feel, will help point out some things you may need like: camber adjusters, bump steer spacers, spring and stabilizer bar changes, shock settings and caster adjusters.

I am probably at 80% on my suspension modifications – an ongoing (primary) process, and a bit less complete on the engine.

Re: Adjustable Toe and binding Reduction: Stage 2 Measure/Ca

Spare rear (thanks JoeZ31) rigged up to measure sweep angle:



Calculations to come when I figure what the fuck is wrong with my toe curve equations/commands.

Re: Adjustable Toe and binding Reduction: Stage 2 Measure/Ca

Glad to see you're underway with this. I just recently got my parts car to the house and have yet to pull the subframe out to get those measurements for you.

Re: Adjustable Toe and binding Reduction: Stage 2 Measure/Ca

Wish I was further. Still need to order Ballistic joints. End game goal is May/June so I have some time to procrastinate.

It will get done, I will not be chewing up tires every 3k.

Re: Adjustable Toe and binding Reduction: Stage 2 Measure/Ca

I think you will find that the toe changes very little (or not at all) within 1" above above and 2" below below a static ride height (with a hub center to fender lower lip height) of about 16". I measured the toe change out of the car (just the crossmember & STAs hanging absolutely vertical) with the suspension unloaded, and stock bushings.

However, you may have different results if you are jacking the suspension up and down with everything connected while measuring the toe. If so, I would be very interested in seeing the figures.

Re: Adjustable Toe and binding Reduction: Stage 2 Measure/Ca

You can calculate the entire 180* of suspension travel using a couple of calculations. No need to sit and measure everything at different heights. Granted I am making a few assumptions (non adjustable toe and camber), but ball park they should be close. Makes life a little easier.

Re: Adjustable Toe and binding Reduction: Stage 2 Measure/Ca

I wanna kit when you make it because I said so :lol:

Re: Adjustable Toe and binding Reduction: Stage 2 Measure/Ca

WARNING! Do Not Buy From Balistic Fab! Unless you like paying for parts you will never get, or dealing with thieves don't do it. Time and time again they have screwed over many people in the offroad comunity. They WILL do the same thing to you.

Read some of these from the Pirate4x4 board. By the way they are so crooked they where banned from Pirate even though they where a Sponsoring Vendor of Pirate.

http://www.pirate4x4.com/forum/showthread.php?t=992142

http://www.pirate4x4.com/forum/showthre … listic+fab

Re: Adjustable Toe and binding Reduction: Stage 2 Measure/Ca

Weird, I had no problem with ballistic. That was like a year and a half ago, maybe things have changed.