Jon in Detroit Chassis #123 Build

[zeitgeist]

I think it looks good Jon. The higher rear fenders gives it a raked look which is what I was hoping for. Congrats on getting it done and still removable.

[jon]

Thanks, I am generally happy with it. I think the car looks better with them than without. I still need to do the other side, and I want to grind/cut/paint the modified fender stays. Maybe some paint will cover up my ugly welds

One observation: I think the fenders in general are going to take a lot of abuse. I already knocked mine over and scratched them when assembling. I expect driving to cause some cosmetic issues over time.

I suppose if they get bad I can buy some aluminum trailer fenders and powder coat them; may look real nice.

Still have not driven with them either, curious to see if they shake in the wind.

[gwnwar]

How about covering them with "clear bra" film for the hood of a car??

[buildercg]

Jon, I'm in the process of figuring out headlight mounts in relationship to fenders. I see your headlights are aligned over the rear of the front fender. I know you haven't driven yet with fender mounted but do you anticipate any problems with interference between the fender and headlight?

[jon]

Apr 6, 2016 18:48:15 GMT buildercg said:

Jon, I'm in the process of figuring out headlight mounts in relationship to fenders. I see your headlights are aligned over the rear of the front fender. I know you haven't driven yet with fender mounted but do you anticipate any problems with interference between the fender and headlight?

Good question. I should do some measurements and make sure before I drive.

Just eye balling it, I think I have clearance. Will confirm.

[zeitgeist]

Apr 6, 2016 16:34:07 GMT jon said:

Thanks, I am generally happy with it. I think the car looks better with them than without. I still need to do the other side, and I want to grind/cut/paint the modified fender stays. Maybe some paint will cover up my ugly welds

One observation: I think the fenders in general are going to take a lot of abuse. I already knocked mine over and scratched them when assembling. I expect driving to cause some cosmetic issues over time.

I suppose if they get bad I can buy some aluminum trailer fenders and powder coat them; may look real nice.

Still have not driven with them either, curious to see if they shake in the wind.

I can see the lower front area of the rear fenders getting plenty of stone chips. Consider either the clear bra like gwnwar suggested or body colored vinyl for the high wear and tear areas. I got my idea of fixed rear fenders from Lotus 7 and clones and may start with aluminum rear fenders with the spat front area covered in black vinyl or the opposite with black fenders with an aluminum spat area. Just ideas to ponder.

[jon]

Vinyl is a good suggestion. I suppose I could cover them with that if they ever get messed up.

I think they are gonna get banged into from me just navigating tools around the garage! The fenders are just in a vulnerable spot.

[jon]

Some slightly better pics in day light. The angle brackets make the rear mounts very strong.

[zeitgeist]

I think it looks good Jon. Looks less squat in the rear from both the side and rear angles. I think I'll plan on starting off with fixed rear fender mounts instead of even trying the regular way. Thanks for sharing the work.

[jon]

First HPDE in the books. Great time! The car was fast, and a ton of fun. Driver skill is a limiting factor The car never felt on the limit - it can go faster.

Some metrics: My Exocet is 4 seconds on average faster around this track than my old Miata. I am on stock power, so that is all due to weight reduction (and some nicer components). Granted, my old miata was a POS, and had all kinds of problems, but this is a direct A to B comparison.

My top speed on the back straight is only 4-5 mph faster than the old car. That means most of the time I am getting is attained in the corners. The exocet has the aero dynamics of a brick, so one shouldn't expect top speed to increase. The improvement I get is likely entirely from the increased entry speed.

Also, I think I was the most popular person there. Exomotive should pay me commission. I think i sold multiple Exocets.

I had a few problems too:

1. I sheared a lower wing bracket bolt. This is the bolt that goes into the frame. I highly recommend that everyone look into cross braces. I also do not think that 1/4" bolts are right. They should be sized larger. My bolts were not over torqued. The lower bolt was the one that failed, so the wing pushes into it in compression. It broke from lateral forces on the wing, not downforce.

2. I need to improve the fuel filler. It is hard to fill and the threads leak at high G.

3. I have an idle control problem that is cropping up. I probably need to clean the ISC.

Now for the good stuff!

A random lap (not my best, or worse):

[jon]

In the process of removing the wing mounts to drill and tap the broken bolt, I ended up shearing two more bolts! I do not trust these bolts at all now.

Thus, I highly recommend everyone look into replacing the 1/4-20 bolts that hold the wing on. I retapped all of mine to M8 bolts and got flange heads. I am also going to add cable supports to limit lateral movement.

To be clear, I believe that the lateral movement of the wing is causing the failures - not the downforce.

Exomotive is aware of the issue and is going to address it. In the meantime, please be careful. Mine is not the only failure observed.

[jwagner]

Great info on the wing mount bolts. I'll probably move to hardened bolts and some kind of cross brace based on what you have seen.

[jon]

The included bolts are hardened. Still not enough.

[jon]

I am trying to improve my fuel filler. I extended it a few inches. Helped a lot. I can fill faster and get a full tank.

However, it doesn't look as clean now sticking out the top. Hopefully no leaks around the cap like I had been having.

[einy]

Looks like it is time to fabricate a custom pipe set, sort of like what Jim Wagner took on in his build ...