Duke's'72 Carbed KA project

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duke
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Re: Duke's'72 Carbed KA project

Postby duke » 26 Apr 2016 13:53

The second autocross of the year was about a week ago and I was excited to test out the new front suspension upgrades. The car performed flawlessly. The front end handled the rough terrain of our autocross venue awesomely. There is one area of the venue that we call the “go cart” that is particularly rough. If this section is included in the course I have typically struggled. With the new shock setup the car was smooth and predictable. Even on 2 year old slicks that are getting very near the end of their life I was able to win my class end up with the 4th fastest time of the day. I'm pretty happy with that result. Here are a few pictures from the event.

Image

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Duke Schimmer

'72 2-Door 510
"Simplify and add lightness."

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Re: Duke's'72 Carbed KA project

Postby 5teN » 26 Apr 2016 22:09

Hi Duke, where do you auto cross? Cheers
Spencer

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Re: Duke's'72 Carbed KA project

Postby duke » 27 Apr 2016 14:44

I auto cross with a club called ESCA at the Sonoma County Airport.
Duke Schimmer



'72 2-Door 510

"Simplify and add lightness."

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Re: Duke's'72 Carbed KA project

Postby duke » 21 May 2017 16:30

I have been a bit quiet on the updates lately(but I am about to dump a bunch of 510 stuff on here soon), not because nothing has been happening with the car, but because I have been so damn busy! Before I get to what has been going on with regards to the Datsun, I'll give you guys a little taste of what else has been occupying my time.

For the last few years my dad and I have been kicking around the idea of building a lakester to go land speed racing with. My dad has been really into the land speed scene for quite a while, attending the Bonneville Speed Week almost yearly for the last 10+ years. I have gone with him a few times and have always been fascinated and impressed with the innovative and creative approaches people take to building a car to go fast on the salt. I also love that you will see everything under the sun out there, from Geo Metro's trying to go 120 mph to multi engine streamliners trying to be the first wheel driven car to go 500 mph.

Late last year my dad mentioned to me that one of his friends was looking to offload an I class (under 1000cc engine) lakester in preparation for starting a new project. Apparently the car had a bit of a storied history, and had a lot of potential, but nobody had ever been able to get it to run really fast. I was immediately interested. A few weeks later we arranged to go take a look at it to asses if it was something that we would be interested in buying. Upon first sight of the car I was all in. Once I strapped in to make sure that I fit (you will see what I mean when you see pictures of the car) I couldn't contain my excitement. The thought of going 200+ mph on the salt in this thing was firmly planted in my mind. A week later and we were offloading it from the trailer and into our shop.

Plans for modification started brewing on the drive home. The car is currently torn down and we are in the process of widening the track as well as moving the front axle forward and revising the front suspension. The next order of business is going to be fabricating a new tail section that will be a bit shorter and more aero than what was originally on the car. From there we have a few more things to button up but we should be on track to be on the salt this year for Speed Week 2017. Our goal is to run the car as much as possible to get comfortable with it and iron out any kinks. If that all goes well we may try for the current IFL class record of 221 mph, but honestly that is more going to be something that will be on the agenda for upcoming years.

Picture from a standing mile event the car ran a few years back. Because of some issues it never made a full pass.
ImageIMG_1179 by Eldukerino, on Flickr

And in our shop. You can see how small it really is!
ImageIMG_1184 by Eldukerino, on Flickr

Here are a few pictures of the car from when it was for sale a while back as well as an interesting article ( http://www.ridelust.com/death-wish-nitr ... -facelift/ ) that we stumbled across. If you want to follow along with the build, my dad has a thread going over on the land racing forum that can be found here: http://www.landracing.com/forum/index.p ... 445.0.html
Duke Schimmer



'72 2-Door 510

"Simplify and add lightness."

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Re: Duke's'72 Carbed KA project

Postby duke » 22 May 2017 12:24

After much deliberation and planning, I have finally decided to dive down the rabbit hole of installing rack and pinion steering on my car. Like many 510's out there, my steering box was badly worn, and definitely one of the main weak points of the chassis. I have seen many different iterations of rack and pinion installations in 510's, some better than others, and in this research I set a few ground rules for what I wanted.

1. Keep the rear steer setup-I didn't want to have to make new steering arms, a new front sway bar, etc.
2. Keep the oil pan rear sump- With how low my car is, I really like the security of having the crossmember there to guard the oil pan.
3. Use a new rack and pinion- As awesome as the MR-2 rack setups that I have seen are, I don't like the idea of using something that is 30+ years old and can be difficult to find. Also, I didn't like how slow the ratio's are for most stock steering racks.
4. Make it bolt in- I want to use the stock steering mounts on the frame rails to mount the rack, essentially making it a bolt-in affair.
With those guidelines I set about selecting a rack.
I initially was ready to buy a custom built rack. I even went as far as drawing up a print for the necessary dimensions. However, after a few misleads and concluding that it would just be to damn expensive, I stumbled upon a CAD drawing of a MKII Ford Escort steering rack. After taking some measurements, it looked like it would be a good fit. The pivot points were a little wide, but I had plans on how I could correct this. The big plus for me though was the aftermarket support. MkII Escorts are like the Ford Mustang of England. I was able to find steering racks in all types of ratio's, BRAND NEW! I decided to bite the bullet and order one. To my surprise it arrive 3 days later from around the world. Crazy how good international shipping has become.

The rack required a bit of modification to work. I chucked it up in the lathe and turned the left side mount round (they are normally D shaped like most stock racks) so that I could more easily fabricate a chassis mount for it. For outer tie rods I got lucky in that the outside to outside width is similar to the stock 510 width. Because of this I was able to use 14mm female heim joints for outer tie rods. This allows me to adjust bump steer by using spacers to move the tie rod down with respect to the steering arm.

ImageDSC01006 by Eldukerino, on Flickr

To mount the rack to the chassis I used the existing holes in the frame rails for the steering box and idler arm. I also ran some smaller tubing rearward to some captured nuts just to give it some more support. I made doubling plates for the wheel well side of the holes to hopefully give me a little more stiffness. I then positioned the rack as optimally as possible while still having clearance between it, the oil pan, and the front of the transmission. I would have liked it to be a bit higher, but space constraints didn't allow this. To be able to get it far enough forward I had to modify my current oil pan for clearance. Honestly, it was all a game of compromises. I had a very small space in which to mount it and I knew that the final location wouldn't be completely ideal. I was confident that would have enough adjustment for bump steer that I could optimize it once everything was in place. The mounting structure was fabricated from various diameters and thicknesses of mild steel DOM tubing, with an emphasis on making it as stiff as possible to minimize deflection while driving.

ImageDSC01000 by Eldukerino, on Flickr

ImageDSC01008 by Eldukerino, on Flickr

ImageDSC01001 by Eldukerino, on Flickr

ImageDSC01002 by Eldukerino, on Flickr

ImageDSC01007 by Eldukerino, on Flickr

ImageDSC01009 by Eldukerino, on Flickr

ImageDSC01010 by Eldukerino, on Flickr

ImageDSC01001 by Eldukerino, on Flickr

ImageDSC01011 by Eldukerino, on Flickr
This guards the pinion on the steering rack. Just a little extra insurance against damaging the rack.


For various reasons I decided against using the stock 510 steering column. I wanted to move the steering wheel down and back a significant amount, and doing this with the stock column would have been more work than it was worth. I made my own shaft support that bolts to the stock mounting point on the dash. This utilizes 4 tubes in a parallelogram to allow the column to be moves up and down so that I can position it where I want it. The steering shaft rides in bronze bushings that are pressed into the support. There are 2 U joints in the shaft, one in the car and one at the rack. I used Woodward Steering U joints and other components though-out the steering system.

I also had to modify the header to clear the new steering setup. With where the steering shaft comes though the firewall it left me very little space to snake the exhaust through. I pretty much had to rebuild the whole header to re position the collector so that I could make it though the small space that was available. In the end I have about 3/8" clearance all the way around the exhaust.

ImageDSC01029 by Eldukerino, on Flickr

ImageDSC01040 by Eldukerino, on Flickr

ImageDSC01032 by Eldukerino, on Flickr



To say that I am happy with the new steering setup would be an understatement. Because the rack is brand new there is NO steering slop, and the quick ratio is perfectly suited for autocross. Steering effort is perhaps a bit higher than stock, but honestly I haven't really noticed a huge difference. Because of the quick ratio, it is a little twitchy at higher speeds. You have to be careful with your steering inputs as there is now zero play in the wheel, so when you turn the wheel, the car MOVES! I also really like the new steering wheel position. By moving the column down about 3" it has given me much more leverage on the steering wheel. Previously I would find myself hunching forward in my seat in an effort to get closer to the wheel. With this new position I can comfortably sit back in the seat and still have good control of the wheel.
Duke Schimmer



'72 2-Door 510

"Simplify and add lightness."

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Re: Duke's'72 Carbed KA project

Postby duke » 22 May 2017 12:41

A few more pictures of the whole thing installed.

ImageDSC01016 by Eldukerino, on Flickr

ImageDSC01018 by Eldukerino, on Flickr
Duke Schimmer



'72 2-Door 510

"Simplify and add lightness."

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Re: Duke's'72 Carbed KA project

Postby 510rob » 22 May 2017 19:17

That's excellent.

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Re: Duke's'72 Carbed KA project

Postby Heinrich » 22 May 2017 22:10

very nice.
exceptional skills.
Progress is slow, but it is progress non the less.

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Re: Duke's'72 Carbed KA project

Postby 510wizard » 23 May 2017 07:29

Very nice in the design and the build. I have always been in favor of using the existing holes from the old mounting for the rack. This is following what Flaming River does for their rack mounts for old cars. One thing that they do different is the way they mount the tie rods( what I call traveling rod), which allows them to move the rack input shaft over to where in streering box input was in the stock position and also allows for adjusting bump steer in design.

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Re: Duke's'72 Carbed KA project

Postby greenthumb » 23 May 2017 08:22

Fantastic fabrication! My hat is off to you sir. I love the one casual post that you're going to dive down the rabbit hole, and then bam, it's done. I can only imagine the hours and hours of planning and fabbing. Brilliant solution

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Re: Duke's'72 Carbed KA project

Postby duke » 23 May 2017 12:49

Thanks guys. The actual fabrication for the rack install really wasn't to much work (honestly modifying the firewall may have been the biggest pain in the ass) but all the things I ended up doing "while I was in there" really took a lot of time!


Another one of my "winter projects" was upgrading the front brake calipers. The goal here was mainly weight savings, but also the ability to run 13" wheels (which ended up not happening because of the steering, but oh well). I did a lot of research into what calipers to buy and I wasn't able to find a traditionally mounted caliper that fit my needs that would be simple to adapt to the 280zx struts. Because of this I decided to go with a radial mount caliper. I selected the Wilwood Ultralights after reading a long thread on a Miata forum about a kit that Flying Miata offers that uses these calipers. They seem like a good lightweight caliper that will be well suited to my needs. I machined a bracket that bolts to the 280zx struts to be able to mount the calipers. I took care to make sure the calipers were as close to the rotor as possible to maximize wheel clearance.

ImageDSC01020 by Eldukerino, on Flickr

To go along with the weight savings from the calipers I purchased a set of aluminum hubs from Techon Toy Tuning. With these and the calipers I have saved 9 lbs of unsprung weight per strut! I was amazed when I weighed the assembled struts side by side.

ImageDSC01013 by Eldukerino, on Flickr

As you can see, I also had a bunch of stuff electroless nickle plated and anodized. I'm really happy with the finished look it gives the suspension.

The brakes have a great feel to them. Piston volume is a bit less than the 280zx calipers so the pedal is a bit firmer than it was previously. I was a bit concerned about caliper flex as I had heard that this is a common complaint with Willwoods. From my initial assessment, they seem to be plenty stiff and provide a very good pedal feel.
Duke Schimmer



'72 2-Door 510

"Simplify and add lightness."

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Re: Duke's'72 Carbed KA project

Postby icehouse » 24 May 2017 22:05

So it's quicker steering but is it have less overall wheel angle?

Me and Sam swapped over to rack and pinion on our daily 510's in one day. I thought we did something wrong at first, but it's exactly as you said. It's weird having tight steering in a 510 haha.

Awesome build! I want a set of your caliper brackets. How much :)
"People don't like it when shit doesn't match their rule of thumb." Sam

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Re: Duke's'72 Carbed KA project

Postby cambo » 24 May 2017 22:14

That is a super cool install. I see that there are a bunch of different ratios available for the MKII , do you know what ratio you picked?

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Re: Duke's'72 Carbed KA project

Postby Byron510 » 24 May 2017 22:28

cambo wrote:That is a super cool install. I see that there are a bunch of different ratios available for the MKII , do you know what ratio you picked?


Funny, I was just about to post the same question - what rack ratio did you end up using?

Great job.

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Re: Duke's'72 Carbed KA project

Postby duke » 25 May 2017 07:05

cambo wrote:That is a super cool install. I see that there are a bunch of different ratios available for the MKII , do you know what ratio you picked?


Yes, I used the quickest available, which is 2.2 turns lock to lock. If I were to do this on a car that is more primarily street driven, I would go with a little slower ratio, but for what I wanted it is awesome. Slaloms and quick directional changes in autocross require much less steering input now, but it can be a little aggressive on the freeway. I also used 280zx steering arms which are a bit shorter than the 510 arms, but are designed to be used on a car with rack and pinion steering so the ackerman is better than the stock 510 arms (the scrub radius is also better than a 510 arm, which is a nice bonus).

One thing that I don't like about the MKII Escort rack is the pinion angle isn't optimal for a rear steer application, which is why I had to move where the steering shaft comes through the firewall so that the U-joint angle woudn't be to steep. Just to be clear, MKII Ford Escorts are front steer, so I used a RHD rack flipped over to work in a rear steer car. I also moved the LCA pivots out 1" per side to better match the width of the pivots on the rack.

For people with access to a CAD program, here is a DXF I found of the Escort rack. http://www.super7thheaven.co.uk/escort- ... k-lhd-dxf/
Duke Schimmer



'72 2-Door 510

"Simplify and add lightness."


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