V1 Robinjo #405 Full Cage - 2006 SS/SC Build "Drago"

[Desert Sasqwatch]

This article has some good explanation of caster and scrub radius that maybe(?) can help explain what is being seen with no return to center? One little change in any of the front suspension geometry adjustments will always affect other characteristics. Trying to get to the ideal combination can be a challenge - that's why car manufacturers and racing teams spend so much time testing different combinations to get to their handling goal.

"EFFECTS OF CASTER AND SCRUB RADIUS" (by Mark Ortiz)

I thought some might find this interesting. It was written by Mark Ortiz who was a race car suspension consultant in the 1990's and early 2000's working in the U.S.. I read he got hit by a car while riding his bicycle, and I am not sure what his current status is. But he wrote an ongoing segment...

www.pro-touring.com

 

[Gtstorey]

I may have just got lucky on my initial setup. I set up mine pretty much the same as Ross's recommendations at the time and it has worked so well, I'm afraid to touch it. Tire wear hasn't been perfect but not too bad either.

 

[Rttoys]

I drove about 50-60 miles today. Mixed driving back roads, small town and freeway. At higher speeds, going through sweeping curves, the goblin returns to center just fine. Slow speed, 90° turns, and it doesn’t return the center very well, but I don’t really have to force it back either.

 

[Gtstorey]

I couldn't tell you if mine returns to center on the 90 degree turns. It feels normal, but I really couldn't say if anything does it in those situations.

When I think of return to center issues, I think of my 1989 Dodge Ramcharge that had a screwed up professional alignment. A lane change was scary since you had to really focus on getting it back to going straight again. It would turn into multiple iterations of adjustments, getting it closer every correction.

 

[Rttoys]

I was just driving, then reminded myself I need to pay attention to report back. Overall it felt “normal”, whether it be normal to all vehicles or the normal for the goblin that I have just got use to.

 

[Robinjo]

Drove mine to work today. The alignment overall feels much better. Small bumps on the interstate don't cause the vehicle to dart anymore. It wasn't bad before, but would slightly pull when hitting bigger bumps. Those are all gone. Felt smooth all the way from 0 to 100 (in Mexico) when I did a pull and very solid when applying the brakes coming off throttle.

 

[Gtstorey]

Alignment without addressing bumpsteer will allow steering changes on bumps, especially when the bumps affect one wheel more than the other.

 

[Robinjo]

Alignment without addressing bumpsteer will allow steering changes on bumps, especially when the bumps affect one wheel more than the other.

I know you’ve mentioned this before. How did you determine where the aluminum steering arms from the spindle to the outer tie rod needed to be?

 

[Gtstorey]

Mounted a mirror on the hub to reflect a laser pointer back to a piece of cardboard and adjusted the arm unruly the laser tracked a vertical line.

 

[Robinjo]

Tracked a vertical line how? When the suspension worked? Turning the steering wheel? Where was the laser mounted? Where was the cardboard mounted?
The only clear part here is a mirror on the hub. I’m try to visualise this but am completely lost.

 

[Gtstorey]

Removed the spring from the front coil over. Locked the steering wheel straight ahead. Laser settings beside the car on a box pointing toward the 12x12 mirror on the hub.. Cucled the suspension with a jack. When you have bump steer the hub will turn even with the steering wheel straight. Tracked the reflected laser on a piec of cardboard. What this doesn’t really do is give a you a true “measurement” of how much bump steer you have, even though with measurements you could probably calculate the degrees of bump steer. I just moved the arm until the reflected laser moved as close to vertical as I could get it. Which at about 2 feet from the hub was less than a 1/4 inch from what I remember. I think I had well over 1” when I started.

 

[Gtstorey]

And the 1” measurement was in opposite directions from vertical at top and bottom of the suspension cycle. So more like 2” of total toe change at 2’ from the hub.

You can probably do a search for diy bump steer measurement including the words laser and mirror.

 

[Robinjo]

That makes a lot more sense now, thanks. I need to do this at some point. While the alignment has it better, it's not completely gone. As I turn the dampers to more stiff, it gets worse. I did watch a couple videos on the subject and was still very fuzzy on it all. This may be a winter project.

 

[Robinjo]

Sunday was a busy day. First, swapped in @Rttoys supercharger body to my snout. I have needle bearings and a puller on the way so hopefully I can return his blower at Goblin Fest. Since my blower is out, I removed the screws and ported/polished the unit. Inlet porting was minimal to match up with the throttle body. Also ported the outlet about 1/8". Nothing too extreme. While the blower was out it was the perfect time to do an oil change. Getting the filter out is very easy without a huge chunk of metal blocking the filter housing. Last thing was installing a hood scoop to the bottom of the splitter to funnel more air through the heat exchanger. I did remove the splitter to be able to drill 4 holes through it and secure the scoop with some screws. I didn't trust just securing with the double sided tape provided.

Scoop (sorry for it being blurry)


Polish Job


GoblinFest Items (October 4th-6th)

• Make rear camber adjustable
• Tint new screen (at tint shop)
• SC Coupler/Oil change to new unit
• Port/polish my S/C
• Needle Bearing replacement
• Engine oil change
• Hood scoop on splitter
• Headlights

 

[Robinjo]

Monday night I replaced the needle bearings (case bearings?) in my supercharger case. Super easy with the tool that both pulled the bearings and allowed me to press the new bearings back in. The kit has a pressing block that fit into the middle of the bearing to guide it in but pressed against the outer meatal housing (race). Also, the it was machined to bottom out at the right height as the bearing should be recessed an amount. So right now I have a needle bearing tool that can be loaned out if anyone needs it, I may throw it on the Facebook MP or back on eBay.

Last night the new headlights came in, wired them to a connector so that I can swap back and forth as I want easily. Fit in with no issues in the original brackets. Need to adjust them a little to shine further out but that is easy.
Insert Photo(s)

And..... dead possum 1, new splitter scoop 0. Looks like I'll be working on version 2 of the splitter scoop. Straddled a dead possum in the road not thinking about the splitter scoop this morning. It's now a gift to the environment (which I'll try to find).

GoblinFest Items (October 4th-6th)

• Make rear camber adjustable
• Tint new screen (at tint shop)
• Needle Bearing replacement
• Hood scoop on splitter (round 2)
• Headlights

 

[G Atsma]

I'm guessing the possum got split.....

 

[Desert Sasqwatch]

 

[Rttoys]

Need to crop that with a scoop

 

[Rttoys]

The critter splitter strikes again.

 

[Mahkoi]

Hopefully the critter splitter gods accept your sacrifice and allow me a critter free drive to work tomorrow for the employee car show. Thank you for your sacrifice.