Pin Drive Width Front Setups?

[Todd Buttrick]

Rod,

I still have to mirror this to the other side so another evening in the garage tomorrow. Like anything, it should take half the time now that I know what the hell I'm doing. Neither upper or lower CA was changed so all should be same with caster/camber, just have to check toe due to the extra 8mm width but I'll check caster/camber for sh!ts and giggles and report back. I was more concerned about the extra 8mm width than anything else. I cannot see any difference whatsoever in the stance as it relates to the fender and trust me, I'm anal when comes to that stuff. Not an issue at all.

[Todd Buttrick]

I got this mod completed and over 300 miles this past weekend. Amazing difference and dramatic reduction in bump steer. I haven't checked the opposite passenger side bump steer to see if it's the same as I simply used the same spacers and setup as the drivers side. This is a better perspective of what my current front geometry looks like.

[skullandbones]

Hi Todd,

Your geometry really got better, didn't it. It looks like your static roll center is significantly lowered. That's what happened with mine even though we did different things. I'm surprised you ended up with the tie rod ends on top but it works according to your video. Are you still going to adjust your rack with the Breeze offset bushings? I haven't done that yet but did do the real measurements on my pickup points by using a friend's 4 post lift. It was so much easier than crawling under the car and trying to "guestimate" the correct points. From looking at the measurements on a full scale cardboard mockup, it looks similar to yours in that the SAI is good and the UCA is angled down. My rack is too high I think but the offset bushing should allow enough adjustment. I took a long curvy trip this last weekend and the car handled like a dream even at speed. I didn't feel any bump steer during that time but I also didn't hit any pot holes. There were some dips though and cattle gratings.

Did you lower your ride height to cause the LCA to change from the original position? I didn't catch anything that you would have done to cause that to go to a parallel position with the ground. Anyway it looks good. Your hard work paid off! WEK.

[Todd Buttrick]

Hey WEK.

The first drawing I'd done was not really accurate with respect to geometry. It was really only intended to show differences in SAI vs no-SAI and the angle of the CAs where a bit of a guess. I did however lower the ride height from 4.5" to 4" which makes the lower CA more parallel. The second pic is more accurate and still a guess as you can't see from dead on with the body on. When you think about it, changing from standard to pin drive width steepens all the CA angles if all else doesn't change like the segments below. I went from standard to pin drive and added SAI which shortens the upper CA even more. That could be good or it could be bad unless you account for the changes. In this case it lowers the instant center nicely and as you mentioned ealier, it looks more like any racecar suspension you see.

The MK1 had built in bump steer issues out of the chute so my car has NEVER felt this good. Like you say, handles like a dream and even at speed. Can't even begin to tell you how delighted I am and learned much from this.

[CraigS]

Todd, I am glad to see you got the bump steer worked out. My tierod is also on the top of the steering arm. Mine is a MkII w/ a partial SAI mod and the Ackerman mod. When I moved the rack back for the Ackerman, I had to use the offset bushings to raise the rack. It is close to the square tubes of the "X" frame so even with raising it I had to notch the tube a little. I think this is why I had to put my tierods on top of the steering arm. I got similar bump steer results to yours. This is also why I always recommend doing the actual measurement w/ the laser. Looking at the UCA and LCA and steering arm in front view just doesn't work. Thanks to Dave Borden where I first saw the technique w/ the laser 90 degrees to the rotor.

[Todd Buttrick]

Craig,

The laser technique is sweet. I have a bump steer gauge but would have to remove my pin drive adapter and caliper to get it rigged up. Like this technique much more. Thanks for the info!

[LukasM]

Hi Todd!

Not sure if you remember me, I came to visit you in MA about 15 years ago with my girlfriend, uncle and cousin and got a ride in your sweet blue Mark 1. I ended up buying a kit at some point and importing it to Austria, where it sadly sat unfinished for a long time because I lived abroad and then traveled around the world for a few years....

Said cousin has now bought himself a Mark IV kit, and and we have a great garage setup in our home town Vienna with all the tools, so I'm finally going to get back at finishing mine as well!

Since you are one of the very few people with a Mark I, and pin drive 15" wheels like me, are you still running the same setup with SAI mod and SN99 spindles as you did 5 years ago? I have SN95s with the dog leg but could switch them out if the wider SN99 still work without sticking outside the body.

Thanks for your input!
Lukas

[Jeff Kleiner]

Lukas,
Sorry to have to share this news with you:

https://thefactoryfiveforum.com/show...light=buttrick

The welcome that Todd gave you years ago is just another example of his willingness to share with others.

Regards,
Jeff

[LukasM]

Man, so sad to hear this.... I met him briefly after his wife had passed, and he still took the time to share his passion for FFR with us. Definitely influenced my decision to buy the kit and now my cousin, who saw his first burnout when Todd and I drove off...

Super nice guy and will surely be missed by many, my sincere condolences to the family.

Thanks for the heads up Jeff.

Cheers,
Lukas