LocostUSA.com

So I'm starting to work on designing my car and I have a few ideas, both concrete and abstract to work out. Awhile ago I posted a topic about a possible solution to an AWD setup, but due to lack of parts availability and after taking apart a FWD transaxle I've come up with a different design. I haven't started picking up parts yet because I want to have a good amount of the design done before I start gathering too many parts, and I'm also fairly broke at the moment (still in school and working part time). So at this point my locost is purely in the design phase. Given that I plan to work on learning SolidWorks since I got a student copy from a friend a few years ago and start modeling out the frame. I'll be using the VSusp website for most of the suspension geometry then translating that into Solidworks.

Now on to the actual Ideas part:
Drive train:
2.8VR6 engine from a VW GTI/Jetta/GLI/Passat/where ever I can get it.
Quicktime Bell housing from Jegs
Tremec T5 from a mid-'90s Mustang
Custom Transfer case using FWD transaxle R&P gears and Diff (more on that later)
Ford 8.8 IRS diffs front and rear, Auburn Ected in the rear
215/45R17 Tire size

Suspension
SLA all 4 corners
Full custom (control arms and Uprights)
Enough Camber gain to eliminate Track width change due to bump
Ackerman Steering
Roll center at least within the chassis
Rear roll center higher than Front
around .5" scrub radius
Caster, Camber, and Toe adjustments all independent hopefully using eccentrics

Frame:
Keep the Lotus look with body work on
Probably around 6-12" of stretch (mostly for the Transfer case behind the seats)
A couple of inches extra height
Integrated roll cage
space for 2
Engine slightly offset to the right
overall weight of around 1500-1700 lbs

I'll be putting the drive train together first, and then stretching it out to fit the passengers with the transmission down the middle and the transfer case behind the seats. The transfer case will take input on the right side and put it through a ring gear from a FWD transaxle to a pinion from the same transaxle and into another ring gear which sends power to the front and rear diffs via a Torque biasing center diff (probably a Peloquin brand). It will be mounted directly in front of and possibly with the outdrive directly attached to the pinion shaft of the rear diff. Once the drive train is modeled I will add the suspension since the width of the frame will be determined by the width of the Diffs and where the axle CVs are. I'm thinking of using Thrust rated Heim joints (1765lbs thrust load) instead of ball joints and Rubber or Poly bushings for the frame side. After the drivetrain and suspension have been worked out I'll build the frame around everything.

So, what do you guys think? I know I'm probably being over ambitious but I can't help it I'm 23, and I won't get too much help while it's all theories, but any input would be greatly appreciated. I also need to get CAD models of the various drive train components so I can start mocking things up, does anyone have a good source for these? I'll have to read through all the Car9 stuff and start to work on the Tutorials for SolidWorks. I'm shooting for a budget of around 10K and a lot of trips to junkyards for parts, and I'll probably be adding in more after the car is built but that's normal.

Some thoughts, not necessarily well thought out.....

And as a preface, I like your idea! So, don't take this as raining on your parade or anything, just want you to have a good chance at actually getting done if you start going beyond the dreaming stage.

A custom T-case is going to be ALOT of engineering, R & D, and machine work, and you might potentially having to make it more than once in order to get it to work right. Do you have the desire, skills, and / or budget to make it happen? I am pretty familiar with a Bridgeport, and I'm not sure I'd take that kind of thing on (I'd like to think I can, but can I really pull it off?). My buddy who's been "turning handles" for 40 years could pull it off, but can I without needing him to hold my hand the "hole" time.... You really need to evaluate whether you're willing & capable of going there, since most of the AWD concept revolves around that very piece of hardware. And if you can't make it yourself, can you afford to be paying $50-$150 an hour to a machine shop to make it happen? Custom machine work is really expensive....

If not, start thinking about readily available tcases and how they might be integrated. I might suggest the BW4472 (by Borg Warner). Used in AWD Astros (thru '98?), Bravadas (thru '97), Syclones, and Typhoons. Capable of serious power (900+hp), fairly cheap & plentiful in salvage yards, parts are available. Viscous Coupling design with 35% / 65% front to rear bias. 27 spline GM input (which wouldn't match up with a Ford pattern T5, but a Chevy T5 would), and are available with 27 or 32 spline rear output. Don't remember what the front output is (splines, flange, but it's something) but it is chain drive (Morse type chain, I think it's 1.25" wide). Comes from GM as a Driver's side drop. Would probably be desirable to spin it and make it Pass side drop (there's enough going on in the driver's footwell of a 7 type vehicle already), but I'm not sure how oiling would work out. There would certainly be some small R & D there. Weighs about 75 lbs. I think the case is aluminum, but might be magnesium (some of the later New Venture cases are Mg.) I think you'd need to make an adapter to mate the T5 to the BW4472. You could use a 4x4 S10 T5 case / tailshaft, which would at least make life a little easier. Might need to mix and match other internals to get the correct gearing, input & output shafts.

But there are certainly other choices for Tcases.

Ford 8.8 IRS questions: (you don't have to answer these now, but things to start pondering)
From what stock application? What ratio & splines? Alum or Iron case? What half-shafts are you planning to use? Are they going to be a stock size or custom (big $$$)? Do the CV joints in whatever those shafts are have enough articulation for the front axle (for example, does an Explorer rear half-shaft fit your needs, and if so, does it have enough flex to use on the front)? How about the front shafts from F-150 8.8 IFS applications? How much power are you expecting to send to the front diff? Will it survive running on the "coast" side with that much power? What are you going to use for wheel hub / bearing assemblies? How are you going to get the offset in the front diff you need to clear the engine / propshaft, since the IRS setup is pretty much centered.....


I'm brainstorming a similar kinda build, so I've kinda thought through a few of these questions for myself. But my goals are a bit different, so I'm sure it's not apples to apples... Mine is going to be 400 SBC (already have one and love the sound of a healthy V8) / T56 / BW4472. I'm thinking of using the front & rear diffs & half-shafts from the Cadillac SRX / CTS / STS, but haven't laid my own eyes on them to decide if I think they'll work.


Something that alot of the experienced guys will probably tell you is to only bite off so much really radical stuff. If you dive into a whole bunch of uncharted territory, your chances of completion drop fast.... I can't say that for myself, because I haven't gotten past the dreaming stage and into the drawing board /CAD stage. But I'm trying to keep from building a completely new design from the ground up. I just don't have the skill / time / budget.

JustDreamin

Wow, that's quite a reply. About the T-case (and other custom parts), I'm going to try to have as much of it as possible designed to be Plasma Cut rather than machined. The Knuckles (uprights) will be the same way, Plasma cut out of Plate then fit together like a 3D puzzle and welded. I do realize that I'll have to be careful not to warp the parts while welding, but don't think it's going to be too big of a problem. I plan to do the T-case using the bearings from the transaxle, the only thing I really need to ensure is my gear mesh, which may require having the gears, for now I may just kinda have to guess at the size.

The diffs will probably come from an Explorer or Expedition (easiest to find), though an aluminum unit from a T-bird would be preferable. I'll probably be using 3.27 or 3.31 gears (as little as $60 a set used at Randy's Ring & Pinion) I'm planing on around 170-200hp to begin with, about what a stock VR6 will put out. After I get the car built and driven for a while I'll start thinking about more power. I'm looking at the Dodge Grand Caravan hubs in 5x114.3 since they are a bolt-on design with a common tuner pattern (many Japanese 5 lug cars use it). I'll probably be centering my diffs, so that the axles, and arms can be the same on both sides (easier to build and have replacements for) and the knuckles will be mirrored. I'll get the driveshaft past the engine by offsetting it slightly (a couple of inches) to the Right and because the VR6is a fairly narrow motor, and if need be I'll put a CV in the middle or something. I'll have it at a 50/50 power split (unless one side slips) and I'm pretty sure that the Ford 8.8 will survive at below original power levels with less than 1/5th the weight to move.

Hey there FireStorm005.....

I think plasma cutting those bits and pieces isn't a bad idea. In fact, it's a pretty good idea. Sadly, it won't fix the problem of requiring precise machining. The accuracy required to have a transfer case that works will require you to cut, assemble, and weld it fully, then do final machining. Plasma accuracy isn't quite as good as laser or punching, and distortion will happen, no matter how careful you are, especially if you're putting the kind of heat in it that you'll need in order to have a structurally sound part. The MIG "continous spot welding" that you see demonstrated on "Trucks" or "MuscleCar" works great on sheetmetal (really thin, not under a lot of load), but for something thick and structural, you're going to have to put some heat in it, and that will cause distortion.

ltimately, by the time you finish putting that case together, I doubt you'll be able to hold the kind of tolerances you need in order to keep bearings and gears properly aligned without doing finish machine work at the end. You're going to want the bores aligned within .001", bearing & locating holes on size within that kind of tolerance too (and round would be good, as well). As long as that's part of your plan, I'd say it'll go ok. If not, don't expect 200+ hp to go through it and not have issues..... Not a Sermon, just a suggestion....

I think most of your thoughts on the 8.8's sound about right. I do think the front diff running backwards will probably survive at the power and weight levels involved. Any thoughts on half shafts? If you're going to use stock pieces, are your hub choices compatible with the shafts that are available? Custom pieces solve the compatibility issue, but can get really pricey ($400+ a shaft).

Anyway. I think you've got a reasonable plan of attack.... Keep plugging away at filling in the details....

JustDreamin

First off, what's the car for? Bragging rights? Cruising? Canyon carving? Drag racing? Road racing?

The big question is: after it's all said and done, will the extra weight of the 4WD result in a car that's faster than 2WD? For all the extra work it needs to be markedly faster than say, a Caterham R500, if performance is the goal. I suspect that there's a real possibility that it would not, other than perhaps in a straight line. If you've got some data for a 4WD Locost that says otherwise please post it up. Don't forget that driver training may well result in a lap improvement equal to what the 4WD system would theoretically have added...

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Midlana book: Build this mid-engine Locost!, http://midlana.com/stuff/book/
Kimini book: Designing mid-engine cars using FWD drivetrains
Both available from https://www.lulu.com/

VERY good points.

_________________
Fingers of butter and fists of ham.

Except the most important one, ie; "Because I want to".

Cheapracer is right. While I agree that FireStorm's car might not be the optimal configuration, and maybe it's a fine line between pointing out things the builder might not have thought of and discouraging him altogether, but you don't *have* to build the fastest Locost, or the easiset Locost, or the most practical Locost. What is there about building a car from scratch that's practical in the first place? Sometimes you just want to build something. IMO we should encourage people to build the car they want to build, and maybe not the car we think they should build.

Apparently this assumption has to be pointing out occassionally.

_________________
Midlana book: Build this mid-engine Locost!, http://midlana.com/stuff/book/
Kimini book: Designing mid-engine cars using FWD drivetrains
Both available from https://www.lulu.com/

exactly, and because the increase in traction is useful at all times, both in a straight line and around corners, and when the weather isn't as cooperating (as is usually the case here in Washington) the effects are multiplied. I plan to add a top to my car as well, now to see if it will be a hard top. Saw a possible idea in another thread, a video with a twin v-8 street rod where the whole roof hinged up at the base of the windshield.

The first series of questions are good ones. If you're going to race it (ever) what sanctioning body's rules do you need to play by (SCCA, NHRA, NASA, etc) and what class will you be put in. For example, Kurt's Midlana probably doesn't meet NHRA requirements, so he won't be running that kind of event, and I don't know what class the SCCA would put it in or whether it would be competetive there.

I personally feel that AWD makes a high powered car much easier to drive, especially in the wet. Rod's LS1 powered 7 will spin the tires in at least 2nd, and probably 3rd, in a straight line, on dry pavement, without using full throttle.

How about Midlana? How much of that 400 hp turbo'd Honda power can you get to the ground below 100 mph? Can you load up the motor enough to build boost?

The weight penalty isn't a big deal for many folks, I bet. I'd be willing to bet it ads less than 200 pounds worst case. For those guys who are trying to stay under 1500 thats a big deal, but if your goal is 1800 to 2000, that's pretty manageable, especially if you can make the car easier to drive and able to use all the power your engine is capable of making.

JustDreamin

The Explorer 4x4 front diff would be a good choice as it is small and built for a SLA front end. I have a '97 Explorer 4x4. But, there is a big caution with using the transfer cases of any domestic AWD or 4x4 - they are BIG. I'm using a '94 Mustang T5 in a modified Haynes Roadster and it fits OK, but the chassis had to be modified for it, primarily because of the bell housing it attached to, not the T5 itself, which is bigger than most import transmissions, but not hugely so. If you add in a transfer case along side of a T5, or similar sized domestic manual transmission, you're going to have a real packaging issue unless you go right hand drive.

I think the idea of an AWD Locost is cool, and I'm not trying to be negative here, dream big I say. However, I would be looking at smaller rigs like some of the smaller imports that have AWD, preferably with a inline (not transverse) I4 engine. How about something from the Suzuki product line? Is there anything from that line that might work?

Cheers,

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

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

The front diff in those Exploders is a Dana 35. Not known for being overly stout, and virtually no aftermarket support. I wouldn't say it's the worst case, but wouldn't be my first choice. My wife's '99 Moutaineer's front diff was a mess (made all kinds of noise) with under 100k on it.

My approach to using a truck tcase is I'm going to flip it to be passenger side drop, and make the passenger space smaller. That is likely to require some lube system changes.

JustDreamin

I thought of using a 7.5" IFS, but there's not a whole lot of support for them and they have an extension housing coming off the side that I don't want to have. I'm planning on the suspension pickups being inline with the inner CVs and that would make the car way too wide for my tastes.

I'm going to be making the chassis fit around the drive train, not stuffing a drive train into a chassis. I'll also be going with a Divorced transfer case, there will be a driveshaft between the transmission and the transfer case, which will be mounted behind the seats.

Why AWD?
In my case, a much taller vehicle with about an 80" wheelbase and ~335hp, and I realized that sooner or later my responses won't be fast enough. I'll blink, I'll misjudge.

From there, driving AWD daily absolutely hammers home the point that 2WD vehicles are obsolete. Period.
They might not be in Cali, but here in western Canada where temps swing 125*F/year most years and 135-140 on a severe year, and when snow is on the road 5-8 months a year and add one full month at each end where dirt and gravel is all over the road, then yes, 2wd is obsolete. For me. YMMV.

I'm not just raving. I'm 40 years old and likely have driven more vehicles than all but a half dozen members on here.
Further, I'm honest with myself about what I need. I don't want to look like I'm going fast (tickets), and don't want to dance with danger on the ragged edge, I don't want to run against a clock at any sort of time trial at all (except maybe a 1/4 mile once or twice to see how the combo works). Street. Quick. Easy.