innertwist

iTrader: (3)

I started drilling it with an 1/8" bit like Carl suggested on his website but is this really enough to make a notable difference? It seems like no matter how many times I drill it through the rubber just closes up the hole. Has anyone ever experimented with different sizes? I'm thinking at least 3/16", maybe a 1/4" or even larger.

sittinlow88

What is this mod supposed to due? it would seam that you would get worse handling from this???

XLR8

iTrader: (52)

After reading the mod wright-up, I noticed that the bushing on the control arm looks much older then the one you are using. The purpose of the mod is to make the bushing softer and more flexible. If using a newer rubber bushing, it is gong to be much more pliable and you may have to use a larger drill bit to get the same effects.

XLR8

iTrader: (52)

The purpose of the mod is to reduce oversteer. A stiff rear end is great for drag racing. But, when pushed hard in the turns the rear will not flex, so something has to give, and it will be the tires. Of course you don't want the rear to be a sloppy *****, but on the same note you don't want it to have so much tension that there is no flex. Since FB's are known for understeer, due to the "not so efficient" Watts linkage. This mod should help.

The original site helps explain this.
http://www.pbandjracing.com/rear_suspension.html

Rx7carl

Yea its ok if the hole closes up a little. IIRC I said to use a slow drill speed so you actually remove the material and dont just burn through it. Softening the bushing is the goal yes. Also older bushings are softer to begin with which is why the Spec-7 racers like to use them.

Looking at your pic I think you can go a little bigger on the bit. Or drill it multiple times.

innertwist

iTrader: (3)

I don't know how old the trailing arms are but they're definately not new. They were a junkyard special off an 81 iirc. My old trailing arms were rusty old things with very swelled and cracked bushings. There is a night and day difference between them. So what you're saying Carl is that I'd be better off using the old arms? Hmm, I suppose I could shave off the excess bushing and paint them. I think I'll try it out different ways if I ever find a decent autocross place around here.

I think I drilled them as much as I could at 1/8". I did do it very slowly, pulling the drill back as I did to get out as much material as I could (I'm using a hand drill here). No burning. So then, would 3/16" be a good bore?

Thanks guys. And thank you especially Carl for making the tutorial!