LocostUSA.com

Learning how to build Lotus Seven replicas...together!
It is currently March 29, 2024, 1:31 am

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 37 posts ]  Go to page Previous  1, 2, 3  Next
Author Message
PostPosted: July 9, 2018, 10:47 am 
Offline
User avatar

Joined: October 24, 2008, 2:13 pm
Posts: 5326
Location: Carlsbad, California, USA
What's your wheelbase on the model as it stands right now?

Cheers,

_________________
Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886


Top
 Profile  
Reply with quote  
PostPosted: July 11, 2018, 10:58 pm 
Offline

Joined: November 26, 2012, 2:29 pm
Posts: 191
Location: Rome, GA
Lonnie-S wrote:
What's your wheelbase on the model as it stands right now?

Cheers,


105.82 inches as it currently sits. That's center of front hub to center of rear differential axle hole.

_________________
My build -> viewtopic.php?t=15585


Top
 Profile  
Reply with quote  
PostPosted: July 12, 2018, 11:05 am 
Offline
User avatar

Joined: October 24, 2008, 2:13 pm
Posts: 5326
Location: Carlsbad, California, USA
If the Donkervoort is your model, you may want to check their wheelbase figures. Typical 7-type cars are somewhere around 95" wheelbases.

There is a debate about how long the hood line should be on a 7-like car. I wasn't aware of this issue when I designed by car. In practical terms, there seems to be a genuine effect between it's length, placement of the windshield and buffeting at highway speeds. Then there's the aesthetic aspect, on which opinions differ.

You might want to take a look at the couple of threads dealing with it over the last couple of years. There's one pretty current conversation you might check for if you're interested.

I look forward to following your design as you move forward.

Cheers,

_________________
Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886


Top
 Profile  
Reply with quote  
PostPosted: July 13, 2018, 6:46 pm 
Offline

Joined: November 26, 2012, 2:29 pm
Posts: 191
Location: Rome, GA
I know it's not quite donkervoort wheelbase. I'm planning on modifying my design to fit a little better with the donkervoort style design. I put the front wheels in place way before I actually added that picture...

_________________
My build -> viewtopic.php?t=15585


Top
 Profile  
Reply with quote  
PostPosted: August 22, 2018, 10:16 pm 
Offline

Joined: July 30, 2015, 9:05 am
Posts: 45
Location: Mooresville, NC
Meh, if you're going bigger and stretching it out, go ahead and drop a v12 in there :)

Where did you get that human being model?

_________________
To Midi-exo or AWD Locost...


Top
 Profile  
Reply with quote  
PostPosted: September 10, 2018, 3:45 pm 
Offline

Joined: November 26, 2012, 2:29 pm
Posts: 191
Location: Rome, GA
Homemade WRX wrote:
Meh, if you're going bigger and stretching it out, go ahead and drop a v12 in there :)

Where did you get that human being model?


I think I downloaded it from grabcad.... it was either there or thingiverse.

I had to convert it to a solidpart file and scale it appropriately.

_________________
My build -> viewtopic.php?t=15585


Top
 Profile  
Reply with quote  
PostPosted: May 15, 2022, 9:06 pm 
Offline

Joined: November 26, 2012, 2:29 pm
Posts: 191
Location: Rome, GA
Been quite awhile again, haven't had much time to work on the design as I started trucking. Now that I've got my own truck and the money situation is much better I think I'll be able to work on the car a bit more.

Here's some updated design pics for you all.

There's quite a bit I need to work on here. The front suspension is almost done aside from the mounts needing to be finalized and the lower control arm toe/caster rod needs to be added. I've designed the bellcrank to be able to be greased without removal as well.

Rear suspension will need to be completely redesigned as I've changed where the pickup points will need to be. Model wise it is fairly close to accurate.

Fuel tank will most certainly be made smaller as I think it is currently ~14 gals and really I won't ever need that. Not to mention its quite close to some chassis parts such as the rear subframe assembly. The fuel tank will be held from the bottom by a bracket made with angle iron and have rubber mat wherever the steel would touch the aluminum fuel tank. I'm planning on also bolting it to the back firewall frame with a rubber isolator between the aluminum bracket and the frame.

Image
Image
Image
Image
Image
Image

_________________
My build -> viewtopic.php?t=15585


Top
 Profile  
Reply with quote  
PostPosted: May 16, 2022, 12:26 am 
Offline
User avatar

Joined: September 29, 2020, 8:24 pm
Posts: 152
Read through the whole thread and while brief it's a journey, you've been wanting ti build this car for a decade at this point. Your model is very thoughtful, if your trying to get it all figured out in solidworks I recommend designing your body and figuring all your bracketry (those details will bog a project down)

Hinging the doors with simple low offset hinges to the A pillar like the donkervoort is probably the easiest/ coolest solution.

What are you thinking for triangulation around the front suspension, I'm guessing that's not been ironed out yet?
Attachment:
6a8klgs.png
Here's a shot in the dark that'd tie it together and still have room for a frontsteer rack (Na miata units are front steer)

Wheelbase was mentioned earlier in the thread, I think right around 100-95 is going to be the sweetspot at 72" total width (for reference my cars 97.5" wheelbase) You'll have plenty of hood to get the right proportions, I'd be happy to lend a hand with exterior design if it'd help as that's something you'll want/need ironed out soon to figure trunk access, door/hood/ radiator fitment.

Keep the dream goin!


You do not have the required permissions to view the files attached to this post.


Top
 Profile  
Reply with quote  
PostPosted: May 21, 2022, 12:47 pm 
Offline

Joined: November 26, 2012, 2:29 pm
Posts: 191
Location: Rome, GA
sony1492 wrote:
Read through the whole thread and while brief it's a journey, you've been wanting ti build this car for a decade at this point. Your model is very thoughtful, if your trying to get it all figured out in solidworks I recommend designing your body and figuring all your bracketry (those details will bog a project down)

I'm planning on putting epoxy mounted studs on most of the panels except for the large wraparound ones. I'm unsure of how I'll mount the rear bumper for instance. Probably just bolts in hidden areas honestly.

sony1492 wrote:
Hinging the doors with simple low offset hinges to the A pillar like the donkervoort is probably the easiest/ coolest solution.

That's absolutely my plan and partially why I decided on a cage around the sitting area. Means I'll be able to weld bracket mounts to the cage.

sony1492 wrote:
What are you thinking for triangulation around the front suspension, I'm guessing that's not been ironed out yet?
Attachment:
6a8klgs.png
Here's a shot in the dark that'd tie it together and still have room for a frontsteer rack (Na miata units are front steer)

I'm thinking that I will probably add in some triangulation to the front once I figure out the suspension a little bit more as wall as the intercooler and radiator placement. I'm planning on having a V-mounted radiator and intercooler with the radiator venting back and out the sides through louvers and the intercooler being vented via a hood vent. I will have to figure out some flow simulation to ensure I'm not going to be pulling in air from the hood vent. Obviously because of my design for the vents I need to keep bracing somewhat small to not impede airflow. One thought I had was to have small gussets specifically for the front upper control arm mounts and have a bolt in v-brace that will incorporate the intercooler ducting to keep everything separated and still easily accessible. I do FEA testing on the chassis with the suspension rigid so I can design it with the least amount of intrusive bits as possible. The chassis as it stands currently is well over the torsional rigidity of an aussie mods chassis (currently as far as previous front suspension iteration). Keep in mind I'm also using 14ga vs 16ga tubing and 2x1 rectangular tubing all around the cabin.

sony1492 wrote:
Wheelbase was mentioned earlier in the thread, I think right around 100-95 is going to be the sweetspot at 72" total width (for reference my cars 97.5" wheelbase) You'll have plenty of hood to get the right proportions, I'd be happy to lend a hand with exterior design if it'd help as that's something you'll want/need ironed out soon to figure trunk access, door/hood/ radiator fitment.

Keep the dream goin!

Honestly I very well may need some help on exterior design. I'm a little bit in a crappy position currently since I was planning on using a 3d scanner that creality was coming out with, but they got into some legal trouble with it so I'm unsure if I'll even be able to do that and use off the shelf headlights now. Obviously that'll have a huge effect on how the car looks and is designed. Body panel wise I'll be building a large scale 3D printer and fiberglassing over the panels for stiffness. There's a guy on reddit that made a 3d printed miata hardtop and used carbon fiber over it. I need to get in touch with him and watch his youtube vids for a bit of instructions as far as what plastic he used but I think it should work decently well. The nice part is I should be able to run a very large nozzle on the printer to keep it from taking forever since I should be able to smooth over any imperfections with the fiberglass and sanding.

_________________
My build -> viewtopic.php?t=15585


Top
 Profile  
Reply with quote  
PostPosted: November 18, 2023, 10:57 am 
Offline

Joined: November 26, 2012, 2:29 pm
Posts: 191
Location: Rome, GA
Well its been over a year since the last update :BH:

I haven't been able to really go at it like I'd hope because of life. The war in Ukraine is a big factor in that since my wife is from there and has family there still. We've also moved from South Dakota to Georgia, which has been quite an undertaking. In saying those things though I've been working on various parts of the car when I get free time. I bought a 3d scanner to help model parts with before I build them to check clearances which has been a huge help. Before I bought that I also bought the 3d scans for my engine and transmission. Being able to accurately place things has been a huge boon. Because of that I've modeled some of the intake piping, started the engine mount designs, found I could use at least 2.5" exhaust all the way back in the transmission tunnel rather than the side of the car (might see if 3" would fit since turbos like the least amount of restriction as possible).

As far as the front suspension I've decided against inboard suspension because of cost and ease of building. I have not redesigned the coilover mounts yet to facilitate this however.

Intercooler
I plan to use a frozenboost.com air to water system. I'll be using the type 117 heat exchanger, though I may buy a cheap honda half sized radiator and having a buddy of mine weld the inlet and outlet closed to change them to a pipe fitting rather than use the frozenboost unit since it's got some odd mounting design, we'll see. The intercooler will be either the type 8 or 9 kit and mounted above the frame rails over the ducting for the radiator and intercooler heat exchanger. I previously was going to use a larger one but have decided against it.

Cooling
I've decided on using a drag scirroco radiator and mounting it upside down to be able to mount it without having to modify the mounting brackets on it. Thankfully it does not come with a cap on the radiator. Placing it in the model however I've found the lower port on the radiator would run right into my steering rack. This means I'll be swapping racks for this project because the radiator is staying.

Steering
Since I'll be using wilwood pro mustang II drop spindles I can move the steering arm to be front or rear steer on the spindle. I'll be going to a rear steer rack since the radiator will be in the way, and after seeing some center take off racks like the 89-93 Chevy cavalier I figured I'd do some searching. The cavalier racks are hard to find anymore, even if they're cheap still. The input shaft also has a different OD and spline count than my steering column (more info on that soon). I've found that the 02-06 Acura RSX had a rear steer center take off rack that mounted tie rods to arms on the mcpherson strut assemblies and they are about $230 price wise. So a rack that I won't need to cut open to modify and I can adjust the bump steer however I want! I'll post some info on the two racks below.

Quote:
88-93 Cavalier
Splines = ?
Input Shaft OD = 17.42 (11/16 x 36 probably)

Power = 2.66 turns lock to lock
Manual = 2.83 turns lock to lock

RSX
Splines = 36
Input Shaft OD = 17.29

02-04 = 2.63 Turns lock to lock
05-06 = 2.59 Turns lock to lock (Type-S only)



Steering Column
I was originally planning on using my old 02 WRX column and rack and pinion, however since I'll be using a different rack I also decided to see if anyone in the subaru world had sucessfully used an FRS/BRZ steering column in a GD Impreza (02-07) while retaining the GD impreza stalks on the column. These columns also have electric power steering on them that is very easily used with a add on potentiometer setup from a guy in portugal. This will allow steering difficulty adjustments on the fly. The column also has tilt and telescoping functions. I found a guy that had does this exact swap so I plan on doing what he did to swap the stalks on the column. That basically amounts to cutting off the old mounts, enlarging the hole for the new column and re-welding the old mounts to the new column for the stalks to mount to. The clockspring will also need to be modified since the 02 WRX clockspring is 3 turns lock to lock, while the FRS/BRZ one is ~2.5 turns lock to lock. A buddy of mine had a Scion TC column which is exactly the same as the FRS/BRZ columns so I picked that up for $100. They can easily be found with the computer on ebay for a similar price.


Here's the link to the guys writeup and a link to some plugs for the computer for the steering module.
https://b.obsdian.com/category/retrofits/
https://forums.nasioc.com/forums/showpo ... stcount=22

Here is a writeup in a mustang forum that goes over these columns and what they can be found in a bit more thoroughly.
https://www.corral.net/threads/35-elect ... s.2321889/


Rear Subframe
The last thing I've done in the interim is model up a rear subframe. It's designed so the laser cut parts will be used to locate the rear upper and lower control arm mounting tabs easily. It also incorporates the rear differential mounts.

Image
Image
Image
Image
Image
Image
Image
Image

_________________
My build -> viewtopic.php?t=15585


Top
 Profile  
Reply with quote  
PostPosted: November 18, 2023, 12:26 pm 
Offline

Joined: November 26, 2012, 2:29 pm
Posts: 191
Location: Rome, GA
I've also had some time to look at possibly using an electronic wastegate actuator from an F30 BMW.

I've gotten a little ways into this but I'm unsure if I'll go any further since I will probably not be raising the boost much over 4-8 psi. However I'll post what I do have below regardless.

Videos
https://www.youtube.com/watch?v=SCwrkhY ... x=2&t=317s
https://www.youtube.com/watch?v=PUL5DZ9 ... p=gAQBiAQB
https://www.youtube.com/watch?v=ygrsIqW ... ex=1&t=13s
https://www.youtube.com/watch?v=Ozh-Yd9 ... x=6&t=153s
https://www.youtube.com/watch?v=QvXa6GK ... ex=8&t=15s

Controller
You basically need to have an arduino and a motor driver to act as the controller for the wastegate actuator. The wastegate has a position sensor inside it that one of the videos goes over and the motor can be controlled with a dual H-bridge motor controller. An IBT-2 or IBT-4 are going to be the best solutions for the actual motor driver. I picked an arduino Uno but any arduino except a nano will work. You'll also want a DC-DC buck converter to keep voltage at manageable levels. I am sort of unsure how many amps the wastegate uses, but I doubt it'd be over 15. Below I've made a drawing of the wiring that I was planning on using. As far as the libraries for the arduino you will want to make them yourself using some of the videos I've posted for info.

On the left the wires in order from top to bottom are...
Ground for controllers
Power for controllers
PWM boost control signal as (grounded via ecu)
wastegate power
wastegate ground
0-5v wastegate position signal back to ECU, if you want to use it.

Image

_________________
My build -> viewtopic.php?t=15585


Top
 Profile  
Reply with quote  
PostPosted: November 18, 2023, 5:55 pm 
Offline
User avatar

Joined: October 24, 2008, 2:13 pm
Posts: 5326
Location: Carlsbad, California, USA
In the 5th screenshot above, Cody, it looks like the blue objects are the exhaust system. So, is the plan to run it inside the transmission tunnel just below the transmission and changing to a flat, NASCAR type of setup there? Is it going to end where we see it in the screenshot, or will you be adding flat pipe to go to the rear of the car?

What kind of scanner and software are you using?

Cheers,

_________________
Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886


Top
 Profile  
Reply with quote  
PostPosted: November 18, 2023, 7:27 pm 
Offline

Joined: November 26, 2012, 2:29 pm
Posts: 191
Location: Rome, GA
Lonnie-S wrote:
In the 5th screenshot above, Cody, it looks like the blue objects are the exhaust system. So, is the plan to run it inside the transmission tunnel just below the transmission and changing to a flat, NASCAR type of setup there? Is it going to end where we see it in the screenshot, or will you be adding flat pipe to go to the rear of the car?

What kind of scanner and software are you using?

Cheers,


Yup, you're right Lonnie. Blue is the exhaust system, or at least a preliminary model to test fitment. Once i get a little further with the transmission mount design I will probably start actually adding in a bit more detail.

I was planning on doing some rectangular exhaust underneath, but I think I will be able to get away with at least 2.5" tubing underneath, possibly 3" if it goes below the frame slightly. I also am planning on using a minimum of 2 off the shelf resonators, I'll have to see if I can fit them under the trans tunnel or not. If not I'll have one in the transmission tunnel and the muffler will probably have one built in.

As far as the tailpipes, I plan on making them similar to the TVR Sagaris.

ImageTVR Sagaris by John McCulloch, on Flickr




The scanner I'm using is a CR Lizard. I'm also just using their software for it, CRStudio. It works pretty well. Today I scanned a cast iron alternator mount and an aluminum thermostat housing for my engine. No issues. Probably took me 20 mins each or so. Another 15 mins each to modify the model to mount them in reasonably the right location on the engine model I have.

_________________
My build -> viewtopic.php?t=15585


Top
 Profile  
Reply with quote  
PostPosted: November 27, 2023, 7:27 pm 
Offline

Joined: November 26, 2012, 2:29 pm
Posts: 191
Location: Rome, GA
Well I'm back to looking at steering racks. The center takeoff racks have housings that were way too long. I'm now looking between an AE86 manual rack from techno toy tuning or an ~84 Corvette rack.

The T3 AE86 rack is 2.5 turns lock to lock and manual, the Corvette is either 2 or 2.25 turns depending on which model you buy. Either way they'll have to be shortened. Both are similarly priced but the AE86 has an input shaft that is ~17mm. So it MAY work with what I already have.

_________________
My build -> viewtopic.php?t=15585


Top
 Profile  
Reply with quote  
PostPosted: November 28, 2023, 10:36 am 
Offline
User avatar

Joined: October 24, 2008, 2:13 pm
Posts: 5326
Location: Carlsbad, California, USA
If you're OK with spending that kind of money, you actually have several other options. There are several companies that make MGB-derived racks, or Ford Pinto/Mustang derived racks in a variety of widths and in multiple steering ratios in the $300-$500 range depending on features selected.

You might be able to get closer to your ideal setup as far as steering shaft location and angle, inner tie rod pivot location, and steering shaft spline type. Just a thought.

Cheers,

_________________
Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 37 posts ]  Go to page Previous  1, 2, 3  Next

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 53 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to:  
POWERED_BY