Scratch building Bugatti 57SC Atlantic with BMW S65

[Sean in CT]

Ira, i built a bump steer gauge - it really helps to position the steering rack - the height is super critical, though you need some adjustment in case you change caster. I was able to get my bump steer down to 0.030" at 2" bump, even though my rack is too wide.

I can bring it to Wrays this week if you want to use it. There is a plate that bolts to the wheel mounting surface Mine is drilled to 5 x 4-1/2 but you can make another or drill another set of holes if you need. Let me know!

Sean

[in33anity]

Originally Posted by Sean in CT

Ira, i built a bump steer gauge - it really helps to position the steering rack - the height is super critical, though you need some adjustment in case you change caster. I was able to get my bump steer down to 0.030" at 2" bump, even though my rack is too wide.

I can bring it to Wrays this week if you want to use it. There is a plate that bolts to the wheel mounting surface Mine is drilled to 5 x 4-1/2 but you can make another or drill another set of holes if you need. Let me know!

Sean

Sean,
That would be great and I really appreciate it. I spent a lot of time looking at rack specs and ultimately picked up an early 2000's close ratio 911 rack that so far looks like it was made to fit. The Ferrari uses a female thread uniball set-up. Going to cut the ball joints off the 911 tie rods and turn down and thread the outer end to fit the Ferrari joint, At least that's the theory. Be great to have a tool to dial it in!!! Ira

[racer-john]

Just checking in to see progress. Looking good.

[Sean in CT]

Ira - i have it in my truck. Ill be at Wrays all day wednesday, I leave it for you. Keep it as long as you need it. Might want to read up on how it all works. I know Longacre sells a similar device - maybe they have online instructions. Otherwise i can certainly help. I think you have quite a bit of anti-dive. It makes the bump steer do all kinds of crazy things. If you can get it close for 2-1/2" bump and 1-1/2" droop, you'll be just fine. +/- 0.030" will be unnoticeable in a street car.

[Gojeep]

Nice milestone to hit Ira.
Looks like a nice stance to it.

[in33anity]

Thanks guys, much appreciated. Sean, I got the bumpstear tool. The uniball joints didn't show up in time for the weekend,so didn't get to put it to use. I have read up on it, maybe less confusing when I actually use it, but the reading -- not so I Suspect I'm going to need to find a Wednesday in the shop.

In the meantime, progressed the superleggera skeleton. More stressful than it looks!!!

[Sean in CT]

Ira - i saw the car last week - looks REALLY nice sitting on wheels

Ill teach Sam how to use the bump steer gauge (he needs it for his car anyways). Its actually pretty easy...

[John Francis]

You probable know this, but just in case...make sure the spacer sleeves that fit around the head of the cap bolts for the outer tie rod ends (front and rear) are in place.

[Oldnek]

Ira, Just a thought!, I know you have done the bump, and .030"@2" is pretty good by the way, it pays to have a check on ackerman angle as well, if the steering rack is mounted to far forward or back, then your toe out on turns is possibly going to be an issue. You want to make sure that the inside wheel turns in more than the outer. You might of done this already, if so all is good.
Beaut job on the chassis.
Awesome Cheers John

[RockHillWill]

John and the guys, keep us posted on the ackerman situation. If I remember correctly, an appropriate ackerman angle for a front steer car, requires that the ends of the steering arms be outboard of the lower ball joints to have the intersection at the rear end housing. This car has a pretty wide location of the lower ball joint vs the rim of the wheel. I am interested in what you are doing, I LOVE this car!