LocostUSA.com

Learning how to build Lotus Seven replicas...together!
It is currently August 18, 2017, 2:49 am

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 11 posts ] 
Author Message
PostPosted: May 14, 2009, 4:16 am 
Offline
User avatar

Joined: March 23, 2009, 2:57 am
Posts: 50
Location: Snohomish, WA
Preface: I figured I’d write a little blurb about my project to get my build log going. The plan was to write while my daughter took a nap. She took a longer nap than usual so this ended up longer than I really wanted. The upshot is if all goes according to plan (never happens) you should be able to read this post, assume I’ll finish it and go on with your life.

Little background on me first. I posted up in the introduction thread but Chet seems to be the only veteran that hangs out there. I’m a car guy, background is fabrication and engine building. Schooled as a Mechanical Engineer but dropped out of college three years in (with honors) when my European Performance shop was taking off without me. Ran the shop for five years and closed up one day when I was offered my dream job as an automotive consultant on the second largest racing game in the world. These days I only try to work on cars for fun since the five years of doing it for a living nearly killed my passion. My daily is an E36 M3, the baby hauler is an E34 525i Touring with an LS1 swapped in (no kit, 100% my work) and my beautiful, loving Wife has a spotless ’82 Rabbit S.

Clickable thumbnails of the LS1 BMW Wagon
Image Image

On to the car.

I've wanted to build a Locost for years and as soon as I finished my last project I began planning for my very own little sports car. Planning started with a McSorley +4, Rorty IRS and SR20/S13 donor but quickly evolved into a more Caterham-ish design and virtually everything else changed too. Figuring Caterham has been perfecting the 7 since '73 I took a few cues from the current De Dion chassis and started designing. The rear is, of course, De Dion. Not many people seem to build them this way but I just love the way they handle. The joint between the lower A-Frame and the De Dion tube defines roll center and allows me some KRC placement adjustment. The upper links define the rear steer affect and are adjustable. It's the way Papa Chapman built the S2/3 and the way Caterham builds them today.

All chassis bracing omitted from model for clarity:
Image

Up front I've added a kickup to the chassis and the lower control arms mount to the end of the chassis rails which allows me to extend the lower arms slightly and dispose the awkward book designed nose. I plan on running inboard front shocks and have the capability to map wheel rate through travel so it won’t be so much of a guess/check/rebuild issue. More of a define wheel rate curve/move points until it matches/build it once situation.

Other than that and a couple other changes (Lotus based rear structure, dropped N1/2 for arm clearance and some well placed round tubes) it's largely based on book/McSorley dimensions. I added 4" to the cockpit width to fit my race seats and 2" to the height from the scuttle fwd. I also added 2" of length just to the engine bay to ensure there's proper engine room and some symmetry. I’m tacking everything up with the MIG for right now and final welding will be done with the TIG.

The drive train is quite the mish-mash. I'd originally planned on a naturally aspirated SR20 but found them difficult to acquire stateside. Turbo motors are plentiful but the N/A versions aren’t. When we had a BBQ last week with some car friends the game was ‘best engine combination for a Locost’. Suggestions ranged from “HAHA… no” (Ford V8-60 and Cammer) to “Quick, get on the internet and figure out how to make it RWD”. I honestly thought no one would come up with a better idea than the SR until my buddy said ‘Hey, what about a Quad 4?’ Well what about one… they come in 150, 180 and 190hp flavors stock, two companies offer bellhousings to bolt them to a T5, they’re cheap-as-free, can be modded over 260hp N/A for peanuts and they only weigh 300lbs once you’ve removed all the stuff I don’t care about. That was it; decision made. Quad 4 on DCOE side drafts.

I still plan on using the S13 240sx diff, axles and hubs since the design mimics the Sierra with separate outboard hub flanges (plus you can get a OBX helical/torsen differential for under $400), T5 from either a Mustang or a Camaro, Manta or Q4R bellhousing and a neat little Quad 4. As luck would have it Quad 4s were the hot motor in SCCA Sports Racer C for a while and now they’re not… but they’re not old enough to be vintage so the ex-race parts are cheap. Last week I picked up brand new a 7.25” 7lb QuarterMaster racing flywheel for $99 ($600 retail). It uses a 7.25” twin disc clutch which, thanks to the used Nascar parts on ebay, is also dirt cheap. The next day I bought a $4000 set of GM Performance / Crower Titanium connecting rods for a scant $500. A quick chat with an autocross friend went a little like this, ‘You’re using a Quad 4 eh? If you need any parts let me know, I have two complete engines sitting here, pistons, cams, a dry sump… come on over and rummage.’ If deals keep coming up this often I’ll have all the parts to build a killer Quad 4 and no money for the rest of the car. It’s a ‘Locost’ with Ti rods… right.

A little short on space. I pull the cars out when I’m working.

Image

2hr/day for a week and I have this. At this point I’m measuring hood clearance with a set scuttle and nose height.
Image

Until next time…

_________________
I should be in the garage.

-Aaron


Top
 Profile  
Reply with quote  
PostPosted: May 14, 2009, 12:08 pm 
Offline
User avatar

Joined: April 26, 2008, 6:06 pm
Posts: 2834
Location: Under the weather. (Seattle)
Nice start...I like how you're kicking the nose up, although it does also mean the oil pan will likely stick just that much further below the chassis.

_________________
-Justin

Also follow my build on blogspot, tumblr, or instagram and twitter (GarageOdyssey)


Top
 Profile  
Reply with quote  
PostPosted: May 14, 2009, 7:01 pm 
Offline
User avatar

Joined: March 23, 2009, 2:57 am
Posts: 50
Location: Snohomish, WA
The nose is only kicked up fwd of tube E so the pan shouldn't be hanging too much. It also means I can run a standard nose on a +2H chassis without LD (front lower tube) hanging down below the bottom of the nose. Shouldn't be a problem anyway since I'm picking up a Cold nose with an airdam but it's a nice thought. I was walking around a Lotus 340R today at the local Lotus dealer and I kept eye-fondling the front fenders. I didn't have the guts to ask what a new pair cost... if they could even get them.

Edit: Something I forgot to mention about the Quad 4; the T5 adapter bellhousing exists because street rod guys think it looks like an Offenhauser Twin Cam. While I can kind of see the resemblance I found something that hits a little closer to home. When you pull the coils/engine cover off and convert it to plug wires it starts to look a LOT like a Coventry Climax FPF.

Quad 4 in 'street rod' trim. More or less how mine will look.
Image

Coventry Climax FPF in a Lotus 18
Image

_________________
I should be in the garage.

-Aaron


Top
 Profile  
Reply with quote  
PostPosted: May 20, 2009, 10:40 pm 
Offline
User avatar

Joined: September 17, 2007, 10:36 pm
Posts: 209
Location: Montreal, Canada
Great progress! Looking forward to following this one.

That Rabbit is :drool:. The others are too, but I've got a thing for vdubs.

_________________
Concordia University FSAE - Chassis
00 Impreza OBS - RIP
81 Rabbit 1.6D
95 525i


Top
 Profile  
Reply with quote  
PostPosted: May 20, 2009, 11:21 pm 
Offline
User avatar

Joined: January 5, 2007, 6:23 pm
Posts: 101
Location: Charlotte, NC
Interesting build. You might enjoy seeing Wayne Evans' q4 build http://www.texaslocost.com/Quad4page.html.


Top
 Profile  
Reply with quote  
PostPosted: May 21, 2009, 4:01 pm 
Offline
User avatar

Joined: March 23, 2009, 2:57 am
Posts: 50
Location: Snohomish, WA
sorta_se7en wrote:
Interesting build. You might enjoy seeing Wayne Evans' q4 build http://www.texaslocost.com/Quad4page.html.



Thanks, I'd probably been to Wayne's build log a dozen times prior to switching my plans to a Quad 4 but somehow after I made the choice to change plans it never dawned on me to go back. I plan to get by his fitment issues by starting with my chassis a bit larger from the begining (422) and possibly removing the troublesome timing cover and chaindrive system in favor of an open belt system for more bonnet clearance. I ended up stealing almost every picture on his site with a Quad 4 in it for engine reference.

The weekend was semi-eventful. A trip to the wrecking yard provided me with a set of Mustang II spindles. The plan is to use them with 11" Granada rotors (or a Wilwood 11"/alu hub set if the 'budget' permits), custom brackets and Elise front calipers. This will put me at a 5 - 4.5" lug pattern which I can easily match in the back by using N/A 300z hubs and 240sx SE rotors. While 5-lug seems overkill on a Locost it's the only option I seem to have to get the wheel/tire sizes I want with the offset I need. That being 15x7(195/50-15) front and 15x8(225/45-15) rear, 40 offset.

I spent most of my Sunday evening in a friends garage looking at Quad 4 parts, taking measurements and generally BSing the high and low points of the engine, what mods are available, what mods were available and who to talk to for each. He's loaning me a mock up engine for chassis building purposes and when the time comes for the real thing it's likely he'll have a good engine for me too.

_________________
I should be in the garage.

-Aaron


Top
 Profile  
Reply with quote  
PostPosted: June 19, 2009, 2:38 am 
Offline
User avatar

Joined: March 23, 2009, 2:57 am
Posts: 50
Location: Snohomish, WA
I've had a couple of setbacks the last few weeks. I'm on the last week of a 100 day break from work; Microsoft contract work is a 365 days on, 100 days off loop otherwise they have to give you stock. I know guys that have done it for 10 years. Given the economic dump the world took just before I went on my break there's been some question of if I'll have a job next week so we've been playing the tight finances game. Well, word came back on Tuesday that indeed I will have a job.

In celebration of the good news I scored 340sq/ft of RaceDeck tile on Craigslist for $210 and did the floor of my garage. This stuff normally costs $3.95 per square foot so I wasn't going to let the deal slip by me. I didn't do the area under the build table because I weld there but I did get enough tile to cover that area when the welding is done.

Image

Another setback happened while refining my model. I noticed a collision between what would be the 'K' tube in the rear bulkhead and the lateral arms when I went over 4° of body roll. Will I get to 4° of body roll? I didn't want to find out the hard way. The solution was to replace the tube with a 1.5 x 1 x .065 rectangle tube, notch the middle back 1/2 and fill the notch with a 1" wide strip of 16g 1018 cold roll. It's done and welded in. The plate that fills the area between tube K and the suspenion pickup point will be flat patterned out and shaped on the bending brake. Right now the holdup is for mill time to cut the slots where the front heims on the lateral links go.

Image

Still missing all the bracing. At this point I'm just refining the chassis design around the nessesary suspension geometry.

Image

_________________
I should be in the garage.

-Aaron


Top
 Profile  
Reply with quote  
PostPosted: June 19, 2009, 9:57 am 
Offline
The voice of reason
User avatar

Joined: January 10, 2008, 4:47 pm
Posts: 7327
Location: Massachusetts
You mentioned dry sump parts above and you have a small flywheel. Are you going to do that to help fit the motor?

_________________
Marcus Barrow - Car9 an open design community supported sports car for home builders!
SketchUp collection for LocostUSA: "Dream it, Build it, Drive it!"
Car9 Roadster information - models, drawings, resources etc.


Top
 Profile  
Reply with quote  
PostPosted: June 19, 2009, 7:28 pm 
Offline
User avatar

Joined: March 23, 2009, 2:57 am
Posts: 50
Location: Snohomish, WA
I've been looking into it but I don't know how advantageous it would be. I'll have to get everything measured properly but my gut and a few pixel ratio measurements from known dimensions tells me the bottom of the T5 trans is too low to really take advantage of it. I think I can probably chop 1" out of the bottom of the wet sump pan, baffle it and get the pan as high as the trans case without consequence. It's a way cheaper option and more reliable for street use.

The dry sump pans for these motors were intended to be used as chassis members in Sports Racers so they're 1/2" thick in most places. Is there enough advantage in chassis rigidity to outweigh applying torsional loads to what was once a precision machined engine block? Apparently Oldsmobile thought so.

_________________
I should be in the garage.

-Aaron


Top
 Profile  
Reply with quote  
PostPosted: November 30, 2009, 5:01 pm 
Offline

Joined: January 9, 2008, 12:21 am
Posts: 274
Location: Mankato MN
Aaron, get back to work. I wanna see how far you've progressed.



By the way, killer job on Forza 3...Amazing game. I've been playing a lot. Got any job openings? :lol: :lol: :lol: :lol:

_________________
Daily Driver: 2006 Cobalt SS/SC
Good in the corners, good in the straights, but it's FWD...
Locost to the rescue!


Top
 Profile  
Reply with quote  
PostPosted: December 2, 2009, 10:58 am 
Offline
User avatar

Joined: July 22, 2007, 10:58 pm
Posts: 388
Location: Zagreb, Croatia
huh, stumbled onto this build.. :)

I love the BMW conversion.. have a build log somewhere by chance?

_________________
Building a single seater middy BEC with GSXR 1000 power :)
build log: http://locostusa.com/forums/viewtopic.php?f=36&t=5899

day job: http://smg.photobucket.com/albums/v723/turbolimac/portfolio/


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 11 posts ] 

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 7 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

Search for:
Jump to:  
POWERED_BY