Mono shock zero roll for D-13

[Greg Davis]

I am thinking of switching from the dual spring/shock set-up on my D-13 to a single shock system, but don't know if that would require a different exhaust system and trailing arms. Can anyone fill me in on how difficult this is to change from my current configuration? Also, does anyone have one of these systems laying around that they would like to sell?

[kidkoh]

I know that it has been done by a lot of other d13 guys out there but I have never heard of anyone ever sticking with it. I asked the same question about the rear shock and I always got the same answer,it works great so why go and try to reinvent the wheel. After you go through all that work and after you buy a $600 penski shock you will have a car that looks cool and fast but wont handle As good. Save your time and effort and buy yourself a set of tires for christmas

[fvracer27]

I gave this a thought as well just for weight savings ( 1 less spring and shock ) but I would hate to mess with the handling of my car. I have only driven a D13 in FV but I have race many other cars and karts and the one thing I love about the D13 is I almost 100% of the time know what it is going to do when it slides and it that changed I would not be happy. Only advantage I could see is weight savings as the shocks are almost completely out of the air stream already. But you can try it and let me see how it turns out

Mark

[problemchild]

In 1987, I rearranged the rear suspension on my D13. I made a collar and threaded by Bilsteins together end to end. I made a collar and threaded my droop limiters together. Then I made solid links to replace the shocks. In the days before testing, I just put it on the car and went racing. I had won my previous two Nationals with the original setup. I made one adjustment after practice ..... then put it on the pole and won the race setting a lap record that lasted for 5 yrs. I then won the Cdn Runoffs and qualified 6th at the SCCA Runoffs. I don't think that rear suspension got adjusted for a decade and won lots of races and championships with the next two owners.
Don't overthink it. Just move the peices around keeping the basic geometry. Go racing. Use the same basic cambers and droops as you did before. Fine-tune like always.
Cheers!

[fvracer27]

In 1987, I rearranged the rear suspension on my D13. I made a collar and threaded by Bilsteins together end to end. I made a collar and threaded my droop limiters together. Then I made solid links to replace the shocks. In the days before testing, I just put it on the car and went racing. I had won my previous two Nationals with the original setup. I made one adjustment after practice ..... then put it on the pole and won the race setting a lap record that lasted for 5 yrs. I then won the Cdn Runoffs and qualified 6th at the SCCA Runoffs. I don't think that rear suspension got adjusted for a decade and won lots of races and championships with the next two owners.
Don't overthink it. Just move the peices around keeping the basic geometry. Go racing. Use the same basic cambers and droops as you did before. Fine-tune like always.
Cheers!

so you used both shocks? That would be no arrow savings nor weight savings.
did you kept the same uprights?


Mark

[Greg Davis]

I love the handling of the D-13 also. I had a Laser for a few years and hated it's unpredictability. I sold it and got in the Caldwell again and was smiling ear to ear after the second turn. The reason I'm looking at changing the current set-up is that I am punching such a big hole through the air that I am a sitting duck if someone is drafting me. I am thinking of pulling the body in at the rear and making more of a tear-drop instead of the current wedge shape. Also I figure you would lose some unsprung weight with the single shock/spring. Greg, I had thought of a similar system as what you made, but I didn't think there would be enough room for two shocks using the current geometry( I have Carrera rear gas shocks). Could you explain the system you used a bit more, or maybe it would be easier to discuss it in more detail over the phone if you would post your phone #.
Thanks to everybody for their input on this. I know it would be a lot of work and the cost/benefit ratio has to be fairly good before I go ahead with it.

[fvracer27]

Thats the probem with the Caldwell is the hole in the air. Problem you will have if you pull in the body you will never know for sure what you are doing to the air unless you do some wind tunnel testing. You could make is worse. So many un knowns doing it.

If you don't let anyone get close to you they can't draft you or you could set up a oil slick button for when they get close.

[Ed Womer]

Greg,

I think the zero roll off of my car should fit the D13 but I haven't looked at one for awhile. I did have a home built that was a copy of a Zink Z12 with a D13 zero roll and it was a good car. It now is a hill climb car the last time I heard of it. Even though the D13 was a good handeling car don't think for one minute that it was the best thing since sliced bread because we would all still be using that system. Most of the zero roll systems are good you just need to get one that fits and is adjustable to your driving style. Bob Tupper did narrow a D13 many years ago and I think he used the for runner of my zero roll on the car. He was a multiple MARRS champion.

Ed

[brian]

Ed's right. While the zero roll is pretty simple, getting the spring rate and shock valving compatible is very important. One set up does not fit all situations. Angles, length of rockers and general geometry is widely different among cars. Minimizing or eliminating roll steer is equally critical.

[Greg Davis]

Thanks to everyone for their input on this subject. Ed, if you could PM me I would like to get some cost figures from you on your zero roll system.

[Veefan]

I've work with one of Ed's zero roll on my old Womer, it bolt's up to the engine (hard to see the engine bolts) and trans so you do not need to weld any brackets to the chassis.
I have a D-13 now and the push rods mounts are real similar to the Womers also (top right corner of picture)

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[problemchild]

so you used both shocks? That would be no arrow savings nor weight savings.
did you kept the same uprights?


Mark

I used everything. I just made a coupler for the droop limiters and a coupler for the shocks. Yes it was more aerodynamic. It had struts on each side instead of shocks, springs, and droop limiters. I repackaged what was there already and retained the exact handling.

As soon as you change one component, it will be different, then you might as well just install some proven suspension kit from any of a dozen cars.

I am collecting parts and will have atleast one BRD suspension kit available shortly.