Swapping Control Arms for a little more Negative Camber

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jondee86
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Swapping Control Arms for a little more Negative Camber

Postby jondee86 » Fri Mar 23, 2018 8:12 pm

This is a mod that gets talked about a lot. And since I was interested in getting just
a little bit more camber on my AE86 road car, I grabbed a pair of TT132 (IIRC) LCA's.
Apparently these are the same as XT130, RA40 and a few other old Toyotas, and these
are the LCA's that are said to be 10mm longer than the stock AE86 LCA.

However, when I did a bit of searching, I found that the interwebs emphatically state
that these LCA's give anything between no gain in length up to 15mm gain, with a
lot of "i dunno's ' sitting on the fence. So I decided to make this post to try and show
what I found to be the difference. To begin with I hung the arms in a rachet extension
to show how the overall length compared...

Image

Image

The difference does not look like much. and in fairness to the "I dunno's" these things
are incredibly difficult to measure due to their unusual shape. The only true measurement
is from the centre of the bushing shaft to the centre of the ball joint shaft at the point
where it passes thru the steering arm while the arm is bolted to the strut. This last pic
shows why this is the only true measurement... due to the difference in ball joint angle.

Image

I couldn't measure that, but by eyeball and tape I estimate the effective extra length to be
11mm plus or minus 1mm. A 10mm increase is said to be good for an extra one degree of
negative camber, so I'm hoping for around neg 1.5 degrees when I get my alignment done :)

Cheers... jondee86
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totta crolla
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Re: Swapping Control Arms for a little more Negative Camber

Postby totta crolla » Sat Mar 24, 2018 3:04 am

I have adjustable LCA's and from memory 10mm does add about 1°negative camber.
Two things to consider, one is obvious and that is to make sure you have enough thread adjustment on your steering tie rod ends. The other less obvious, make sure the alignment includes the caster setting.
Lengthening the LCA changes the arc that it takes and to avoid having bump steer issues I ended up with about 0.75°less caster than when it had the standard length LCA's.

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jondee86
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Re: Swapping Control Arms for a little more Negative Camber

Postby jondee86 » Sat Mar 24, 2018 2:59 pm

Yes, I can see that there will be some small changes to the suspension geometry. But
I am hoping that they will be small enough that they don't have any significant effect
on handling. Doing some rough figuring, moving the tension rod attachment point outward
by 10mm and leaving the length of the tension rod the same, should move the attachment
point forward by around 5mm and increase the caster by maybe 1.5deg.

A bit more caster is said to be good for the handling of a road car used for sealed sprint
events, but until I drive it I have no idea how it will feel. How far outwards did your tension
rod attachment point move ? And how much caster did you have immediately after putting
the adjustable LCA's on the car ?

You will have more suspension travel than I will have, so bumpsteer will be more noticeable.
But I can dial out some caster in the short term if bad bumpsteer is immediately apparent.

Cheers... jondee86
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totta crolla
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Re: Swapping Control Arms for a little more Negative Camber

Postby totta crolla » Sun Mar 25, 2018 3:00 am

Best bet is to try it and as your car is lower you may find that one of the bump steer adjuster kits would work to dial out any bump steer. As my car is slightly higher than standard I need raise the steering balljoint and none of the available kits appear to allow for this.
Remember that adding caster will increase dynamic camber, combine this with the increased camber from the longer LCA and you may end up with too much camber for good front grip, exactly what happened to my car.

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davew7
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Re: Swapping Control Arms for a little more Negative Camber

Postby davew7 » Sun Mar 25, 2018 4:18 am

A 1.5* caster increase will make the steering heavy. I would take a look at the front lower strut bar. You could probably modify the rubber attaching bushing. Reduce the front bushing thickness then add spacers to the back side of the bushing. You could probably add enough spacers to the back side, to get you pretty close to the stock setting, as long as you have enough threads left on the strut to lock it down, you should be OK. Davew7

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jondee86
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Re: Swapping Control Arms for a little more Negative Camber

Postby jondee86 » Sun Mar 25, 2018 3:46 pm

@davew7 Good thinking. I have grabbed a few flat washers and will put this back
together with a 3mm washer to reduce the caster gain. If the car doesn't feel happy
I will increase that to 5mm worth of washers. There is enough thread on the tension
rod to accommodate the washers without any other mods.

EDIT: Changed my mind. Decided to put 5mm worth of washers in there to start
with. Want to see if that little bit of extra camber make a difference before messing
with caster.

Cheers... jondee86
Give a person a fish, they eat for a day. Suggest they search before posting, and they learn a skill for a lifetime.

zokustyle
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Re: Swapping Control Arms for a little more Negative Camber

Postby zokustyle » Wed Mar 28, 2018 4:54 pm

Do I dare be the one to mention NCRCA's on an 86 forum? No changes to tie rods, sway bars, tension rods, caster, or KPI. But I bet someone will want to argue scrub radius over all of that.

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jondee86
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Re: Swapping Control Arms for a little more Negative Camber

Postby jondee86 » Wed Mar 28, 2018 5:49 pm

If there were NCRCA's for the AE86 that only increased camber by one degree, I would
certainly have considered using them. But to get access to the securing bolts the amount
of camber added has to be around 2.5 degrees, and that is way more than you need for
a road car. So for an AE86 NCRCA's are really only applicable to race/drift cars.

Cheers... jondee86
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