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Tamaren New Reader
3/19/20 2:02 p.m.

In reply to newrider3 :

Sure, I'll upload some more pictures today.

That would be the part that changed, as well as the width. They are now unequal length and have a bit more travel. I will 100% check out that website to double check I'm on the right track and will post some front pictures as well as some measurements. 

Rod ends have been the biggest complaint so far so it's planning on changing very shortly after testing. A lot of this project is fairly modular at the cost of weight because I've never built a racecar before and will end up modifying and replacing parts that don't work. 


Tamaren New Reader
3/19/20 2:33 p.m.

Some front suspension pictures, I have 8 degrees of Cast and 3" difference in length of A arms.

Hasbro (Forum Supporter)
Hasbro (Forum Supporter) SuperDork
3/19/20 2:49 p.m.
Tamaren said:

In reply to Hasbro :

Sure, I'm planning on using throttle bodies from a Motorcycle like a GSXR or Ducati 996/999, although I don't think I need both injectors. It really depends on what happens with fuel management and what someone who knows more than my basic knowledge of fuel management. It will take some work, as soon as I get mounts for Radiators and fuel tank I can work on getting things running and tuning. 


californiamilleghia Dork
3/19/20 3:15 p.m.

Pelican had some threads on using Triumph motorcycle throttle bodies on a 911  motor.

What are you going to use for a VIN number ?

Tamaren New Reader
3/19/20 3:45 p.m.

In reply to Hasbro :

I hadn't seen that- Thanks for the link, I'll probably order a set. Easier than jerry rigging my own for sure.

Tamaren New Reader
3/19/20 3:48 p.m.

In reply to californiamilleghia :

Might work as well. I'm exploring my options right now.

As far as a vin... I have a clean clear boxster title that came with the car, and historically on projects like this until someone tells me I can't, I just claim that it's a Porsche. I drove the 6x6 Jeep through emissions with little trouble and that's still registered as a bone stock jeep. 


dps214 Reader
3/19/20 4:39 p.m.

It's unfortunate that there's no good way to work around it, but I think you're going to find that having the upper ball joints so far inset from the lowers is going to cause issues, particularly on the front end. I think you're really going to wish you could get the inner pivot point of the upper control arms as low and towards the center of the car as possible. As it is now, body roll is going to create a ton of camber gain on the inside wheel (to the point that you might have wheelspin issues without a strong diff), but not much for the outside wheel. For reference, that's about what the rear suspension of our FSAE cars looked like...but we were running a spool rear end so we were purposefully trying to unload the inside rear tire as much as possible.

Purple Frog
Purple Frog Reader
3/19/20 8:13 p.m.


Let's just say I've been down the road you are on.... many times.   I applaud what you are doing.  I did the same sort of build in 1975.   I say go for it.    In case you haven't looked it over, I did much the same  sort of build that I sort of finished  last year.  You might want to look it over for ideas.


If i were in your position, I would start thinking to use a pushrod/bellcrank spring shock system in the front.

I'm not sure you have enough strength so far to handle the torsional forces you will experience.  A cage tying the front and rear together will go a long way.  I realize you are still sort of in the "mock up" phase.  The stress is in the details.  Details,details,details.    Start thinking through fuel systems, controls, ergonomics, etc.

I think its a cool project.   I have my next one on the drawing boards much like it.

pres589 (djronnebaum)
pres589 (djronnebaum) PowerDork
3/19/20 9:53 p.m.

I really like the 928 on phone dials.  I think this is a cool project.  Listen to the others about the engineering, especially on the front suspension.  Good luck and thanks for sharing.

Tamaren New Reader
3/20/20 12:59 p.m.

In reply to Purple Frog :

Thanks! Very cool VW project as well. 
pushrod suspension is a must, and I agree the details have to be perfect. the cage should provide some strength as well

Tamaren New Reader
3/20/20 12:59 p.m.

In reply to pres589 (djronnebaum) :

Thanks! Always loved 928's and had a few

AWSX1686 UltraDork
3/25/20 7:21 a.m.

Very cool project, I'm excited to see how it turns out!


McDesign New Reader
4/9/20 10:39 a.m.

In reply to Tamaren :

Wonderful to watch - thanks for taking the time to post.  Personally myself, I've found that I do "cleaner" work when I know I'll share it with fellow online enthusiasts - especially under the skin!


Forrest in Atlanta

Dammit Reader
4/9/20 11:23 a.m.

We're using M3 ITB's, which handily come in multiples of six:

drivendaily Reader
4/9/20 11:52 a.m.

This is very relevant to my interests, and the work looks great. I've been trying to figure out which transaxles came with which Boxster/Caymans and it's been very difficult to find decent information. Do you happen to have any suggestions for a good breakdown?

nocones UltraDork
4/9/20 12:49 p.m.

For the front upper ball joint you could run dual upper ball joints (with multiple links).  By running 2 ball joints you can project the intersection out into the wheel.   The Nissan 350Z/Infinity G series cars use this design on the lower ball joint.  It seems like it won't work but it effectively a 4 bar linkage with 1 very short side.  This allows it to rotate.  The effective Ball joint location is the intersection of the lines through the inner and outer ball joints of the long links.  The only big issue with this design is that your KPI/Caster will become somewhat dynamic as the relation between the LBJ and the geometric UBJ would change somewhat.  I also believe that the steering takes a bit more load with this design as braking forces would need to be reacted by the steering though the effect would depend heavily on your scrub radius, trail, and spindle offset.

With work you probably could design if so the change is advantageous.  Given your layout I would take that compromise over the very high KPI you have.  

nocones UltraDork
4/9/20 1:26 p.m.

Looks like Gen 2 DSMs use it as well.  Seems common on the tall upright multilink front suspension design.  Which makes sense as the tall upright gives you freedom to place the UBJ in a place that allows you to run very low KPI with 0 scrub but the LBJ in that geometry would interfere with the brake rotor on modern giant brakes.  So enter the dual Lower Ball joint to allow room for brakes and still be able to project a low KPI.

I've not seen it used on the upper before so I'm not sure if there is a reason for that or if it just wouldn't make sense in a mass produced car as you have more freedom to control the design.  In your application (like my Miata based MG Suspension) at least a few hard points become fixed and can't be changed so you have to compromise your way around them to a functional suspension.


Edit.  Found one.  B5 VW Passat use dual upper and lower ball joints on the front suspension.  I know these cars have a history of suspension link challenges but it shows that you can use a dual upper with sucess.

Tamaren New Reader
8/10/20 8:10 p.m.

Wow. I feel terrible that I didn't keep this thread updated over the last few months. If anyone wants an update, Here- 


californiamilleghia Dork
8/10/20 8:57 p.m.
sehr gut
Purple Frog (Forum Supporter)
Purple Frog (Forum Supporter) Reader
8/11/20 9:04 a.m.

Fantastic build!

To do so much in 3 months is pretty special.  Other than a full time job, i'm wondering why mine took so many years.  frown

Put air-cleaners on it.  You'll be glad you did.

I would be dropping a Lotus Europa body on it, with a hatch in the roof.... street legal.  Terror.

I have a feeling we are going to see a lot more neat projects out of your operation.


AngryCorvair (Forum Supporter)
AngryCorvair (Forum Supporter) MegaDork
8/11/20 9:55 a.m.

that's cool!

Hasbro (Forum Supporter)
Hasbro (Forum Supporter) SuperDork
8/12/20 9:59 a.m.
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