750cc V-4 conversion

[godwinmt]

I'm new around here and to open wheelers in general so I'll give a quick intro! My name's Malhon and I'll be a Junior Mech. Eng. student at Rose-Hulman Institute of Technology. I've autocrossed for a few years now, primarily in a 95 Integra I prepped to run in SMF. Our school has a motorsports club which got me involved with SCCA events in the first place, and I've put in quite a few hours working on our '85 RX7 which races F prepared, and our '72 914 we're restoring.

The RWD bug has bitten hard ever since I turboed the integra, and after watching Clemens race in Indy in his LeGrand, I decided the next car would be something light and quick I stumbled on what appears to be a mid 80's red devil a couple weeks ago and managed to pick it up for $1000 from the auction the guy took it to. Some pics of when we first got it:









It is running the Chapparal G44BW I believe it is, and to be honest it has been a royal pain to deal with as far as getting it started. After a bit of chatting with my dad, we determined that that engine did not suit my needs as 90% of the time I will be running it by myself and need something that starts with minimal effort and is a bit more reliable in our eyes. This is where the 750 conversion comes in...

A few years ago I picked up an '84 honda VF750F interceptor. It had sat for roughly 10 years in my uncle's garage, and had severe tank rust etc. I cleaned it up, fixed the tank etc. up, and rode around on it a bit before I realized that at 600lbs, its a bit big of a bike to start out on! Shortly after that, my brother laid the bike over at about 25mph and messed up the front plastics, turn signals, and fuel tank. The engine and transmission run great, the body just isn't with it anymore. We then decided to make the best of both situations and swap the electric start V4 and trans over into the red devil chassis. Pics to follow!

[godwinmt]

We are going to be using the actual frame of the bike as our engine mounts. It is one of the first sport bikes, and the bottom of the rails are nice and flat for easy mounting

Monday evening the teardown began:
Bike at the beginning of the night after yanking the plastics etc.


Dinged up plastics etc.


Fubar fuel tank


Box of removed crap


Wiring harness etc. yanked from the rear along with the rectifier and fuel pump


Other side at that moment in time


Honda V-4 POWER!


Both radiators draining


After simplegreen and some other crap removed


Pneumatic suspension crap


Rear brake/other crap


Lack of radiators is win


Muffler + peg/chainguard yanked


Other side after the same ordeal

[godwinmt]

Last night the goal was to get rid of the swingarm/rear axle assembly and start getting to work on the interceptors wiring harness to integrate into the new chassis

The bike minus its rear end


Wiring harness after it was unloomed...it had a ton more wires than I needed for my setup since I dont' have lights/horn/full gauge cluster/any of that stuff



Some of the wiring/loom that was removed from the harness


Harness after consolidation/orgainization


I ordered a 54 tooth sprocket this morning from McMaster, along with some loom for the wiring. We will be using the same front sprocket on the transmission, and will then add in the other sprocket to the rear. We don't forsee any problems with the smaller sprocket as it will be a purpose autox car rarely going above 70mph. With the 54 tooth rear sprocket, the car will top out at roughly 85mph at redline in 5th.

Tonight I plan on getting the engine pulled from the Red Devil, and tomorrow the cutting of the bike chassis will be underway.

For gearing, I'm looking at the following thrust curves:

[glenn cooper]

Nice little autoX project you got there.
Good luck w/ it.

Hey as a long time M/C industry and racer type, i remember those bikes.
Do yourself a favor and check the camsafts for really bad wear. That gen VF had a huge problem with the hardfacing flaking/coming off of the cam journals and/or lobes.
I'm sure you can dig a little on the web and find out the excat deal.

I like the harness minimization, pretty cool.

Throw all the wheels, body and bits onto the Honda VF/VFR forum/website and fund your project!

What kind of oil pan is on that old lump-a-V4? In the pics it looks really flat, which would be good.
Mock up a clear plastic clutch cover on the crankcases to see how much more oil it would hold and not get whipped by the crankshaft.
Probably/definitely want to run a good bit more than stock level.
How much does the Honda lump weigh compared to the 2 stroke engine and CVT?

That is all, carry on...

[godwinmt]

Thanks Glenn!

I checked the camshafts shortly after we got it back in '08 and they were in great shape, especially for the bike having 18k on it!

I plan on throwing everything on vfrworld when I'm done, and also plan on throwing some of the old 2 stroke/cvt parts on as well.

I have no idea as to how much the CVT + 2 stroke weigh, i'll have to throw them on the scale when I finish, but as for the bike, it weighed just under 600lbs wet. With everything I've taken off of it etc. including what I will be using of the bike frame, I imagine that that assembly will be close to 200lbs.

I really like the clear clutch cover idea! I'll have to do that when I get back to school and have access to more stuff!

The oil pan is retardedly flat. The main thing that will limit how low it can be mounted is the collector where the primaries merge.

I just picked up an actual battery/box/wiring stuff today, and the sprocket will be in from McMaster after while so I'll be sure to update later today with more pictures.

Thanks
M

[godwinmt]

Some updates...
Time to update for the past couple days

Ran into town and picked up a few parts..primarily electrical. Going to get a few more on monday for hooking up coolant etc.


Yanked the radiator and old cooling system from cart


Pulled the jackshaft and started dissassembling everything


Engine prior to removal


Jackshaft and pulleys


Pulsejets of old mufflers


oooooold tires


Icky looking coolant from the 2 stroke


Engine removed


Engine


Axle with hub etc. on it


Axle assembly removed...took a couple hours and a giant bearing puller to get it out. Was being a royal PITA with everything seizing to the shaft as it had sat out for a while at the PO's house


One of the bearings


Rear outer axle supports


Axle


Sprocket from hell (i mean mcmaster) has over 11" diameter


Front of the bike...i think i'm missing something


Frame minus the rest of the frame - dedicated to the 4 sawzall blades lost in the cutting


Engine/frame assy


Another angle


I think its missing something


Converted to single pull/spring return throttle vs push/pull throttle on bike


Rear subframe post lengthening. Wheelbase is extended 11 inches to accomodate the longer engine/giant sprocket


Extension welded in


Entire subframe


Posted by engine/sprocket for comparison of how it will sit


Tomorrow is mounting engine to subframe [] Any other modifications will be during this process. Have to wait till wednesday to get the bearings, but other than that, I have to mount the radiators, fuel pump/rectifier combo, clutch handle/shift linkage, and then wire it up after its all assembled. Really is coming quick!

[godwinmt]

Started today by getting the engine up and hanging from the rafters so I could start the mounting of it to the subframe


Whiel it was up we found a few pieces of the frame which were causing some clearance problems...Myself and my dad took care of that with a little help from the gas axe


Made some trial and error mounts out of wood scraps to get an idea what needed to be made and got the engine setup on them to work out any issues.


Then made the final mounts and welded it all up










And after a quick coat of enamel it sat the rest of the night


Closeup of mounting plate


Tomorrow I order bearings and stuff and start electrical/fuel stuff..yay :P

[jim murphy]

That chassis is very old (I remember when they were road raced) and I suspect metal fatigue in all the usual places that take a heavy load so carefully check for cracks in critical places - gusseting and cross bracing is a good idea as you are about to put a load on a chassis that was NEVER designed for THAT much more HP/Torque especially with the low ratio final drive that you mentioned. You will probably smoke the tires every time you use 1st and maybe 2nd gear to the point that it is uncontrollable - consider a taller final drive ratio and new sticky Hoosier R25's along with stronger brakes. For autox, you will need to increase your front end bite big time so rear tires and wheels on the front is called for and a narrower track in the rear will help the car turn with that straight axle. You have just raised the center of gravity up big time with that heavy MC sitting so high in the back. I would strongly urge you to make the car an one piece chassis from the hinged two piece chassis that it is presently - the rear rubber pucks (if you keep them) will not handle the bigger weight of the MC (looks like coil over shocks are called for) and the one piece chassis will allow very easy corner weighing and predictability in suspension set up. In SCCA Solo, it will probably be classed as an A Mod car once you have developed it and dialed it in.

Good Luck

Jim
Been messing with F440/F500/F600 cars since 1982
Member 600cc Motorcycle committee

[godwinmt]

That chassis is very old (I remember when they were road raced) and I suspect metal fatigue in all the usual places that take a heavy load so carefully check for cracks in critical places - gusseting and cross bracing is a good idea as you are about to put a load on a chassis that was NEVER designed for THAT much more HP/Torque especially with the low ratio final drive that you mentioned. You will probably smoke the tires every time you use 1st and maybe 2nd gear to the point that it is uncontrollable - consider a taller final drive ratio and new sticky Hoosier R25's along with stronger brakes. For autox, you will need to increase your front end bite big time so rear tires and wheels on the front is called for and a narrower track in the rear will help the car turn with that straight axle. You have just raised the center of gravity up big time with that heavy MC sitting so high in the back. I would strongly urge you to make the car an one piece chassis from the hinged two piece chassis that it is presently - the rear rubber pucks (if you keep them) will not handle the bigger weight of the MC (looks like coil over shocks are called for) and the one piece chassis will allow very easy corner weighing and predictability in suspension set up. In SCCA Solo, it will probably be classed as an A Mod car once you have developed it and dialed it in.

Good Luck

Jim
Been messing with F440/F500/F600 cars since 1982
Member 600cc Motorcycle committee

Thanks for the advice Jim! We did check thte chassis over completely for stress cracks etc. in all of the welds right after we got it and didn't find any. The question I have though is when you refer to it as hinged. There was no hinging in it at all. The rear mounts were solid steel where it did mount to the main frame.

Can you point me to the 'rear rubber pucks' as you call them? I really see no place to mount a rear coilover setup as well.

The cars polar moment of inertia has raised a bit, however from what i've been able to see so far, the actual weight of the vehicle has not increased much at all with the addition of this engine compared to the previous setup with the snowmobile engine. The engine is quite a bit bigger, however it is aluminum which saves a ton of weight. When compared against the previous engine/jackshaft/pulley combo that was on the car, we estimate that we've picked up maybe 40 lbs. A good portion of this weight is shifted forwards as well compared to the previous setup which will help to even out the front/rear split.

Front wheels/tires are identical and were when we picked up the chassis. I will consider going to a steeper final drive if necessary, however this engine was a heluva lot easier to modulate when it was in the bike than the old CVT setup that was in the cart and is a lot easier to modulate and control than my current SMF car. I really doubt I will have an overly large issue controlling it, especially with a pair of 7.5" wide hoosiers.

[jim murphy]

Thanks for the advice Jim! We did check thte chassis over completely for stress cracks etc. in all of the welds right after we got it and didn't find any. The question I have though is when you refer to it as hinged. There was no hinging in it at all. The rear mounts were solid steel where it did mount to the main frame.

Can you point me to the 'rear rubber pucks' as you call them? I really see no place to mount a rear coilover setup as well.

The cars polar moment of inertia has raised a bit, however from what i've been able to see so far, the actual weight of the vehicle has not increased much at all with the addition of this engine compared to the previous setup with the snowmobile engine. The engine is quite a bit bigger, however it is aluminum which saves a ton of weight. When compared against the previous engine/jackshaft/pulley combo that was on the car, we estimate that we've picked up maybe 40 lbs. A good portion of this weight is shifted forwards as well compared to the previous setup which will help to even out the front/rear split.

Front wheels/tires are identical and were when we picked up the chassis. I will consider going to a steeper final drive if necessary, however this engine was a heluva lot easier to modulate when it was in the bike than the old CVT setup that was in the cart and is a lot easier to modulate and control than my current SMF car. I really doubt I will have an overly large issue controlling it, especially with a pair of 7.5" wide hoosiers.

The chassis may be older than a 1983 which was hinged at the bottom of the main roll hoop OR it may have been modified to what you saw. You will need to fabricate the frame, axle and panhard rod connections for the coil-over-shocks in the rear - the fronts are there already (may want to reverse these). I am glad to hear the weight increase is only 40 pounds as that MC looks huge compared to the snowmobile motor. And apparently you already have the same width tires/wheels all the way around. The taller final drive will help you control the car at slower speeds.

Please keep us updated with photos.

Jim

[godwinmt]

From what it looks like as far as how the frame is setup, there is a heim/ball type joint about an inch rearward of the rear roll hoop. The main frame rails extend about 2.5' past the back of the hoop where they attach to a cross-member running between them. There are a pair of tubes that run from the ends of this cross member back up towards the front as a triangulated base as well to support the rear. The actual rear subframe attaches to the cart via the front heim joint (maybe what the hinge you're talking about is?) and then is bolted to the very back of the cart on each side by a 1/2" diameter bolt.

Tonight I'm going to start the radiator mounting + electrical stuff so i'll be sure to post pictures as I get them! Thanks for your help again! I know relatively nothing about the origins of the car as the PO had it listed on craigslist as an "adult gokart"

[jim murphy]

From what it looks like as far as how the frame is setup, there is a heim/ball type joint about an inch rearward of the rear roll hoop. The main frame rails extend about 2.5' past the back of the hoop where they attach to a cross-member running between them. There are a pair of tubes that run from the ends of this cross member back up towards the front as a triangulated base as well to support the rear. The actual rear subframe attaches to the cart via the front heim joint (maybe what the hinge you're talking about is?) and then is bolted to the very back of the cart on each side by a 1/2" diameter bolt.

Tonight I'm going to start the radiator mounting + electrical stuff so i'll be sure to post pictures as I get them! Thanks for your help again! I know relatively nothing about the origins of the car as the PO had it listed on craigslist as an "adult gokart"

Yep, it sure is a hinged two piece chassis where the ENTIRE rear clip moves with the suspension. This MUST be made into an one piece chassis as you will have rear steer and bad handling. The only thing that should move is the rear axle with 4 link trailing arms and panhard rod. The front mounting point for the trailing arms will be next to the main roll hoop. The diameter of the axle will need to grow to 1 3/8" diameter to stiffen it (or a bigger tube design). The rest of the axle assembly will have to be fabricated.

Jim

[godwinmt]

I guess I still fail to see how the rear clip will move/steer. I could see some movement with soft mounts in the rear, but with solid mounts and a solid ball joint up front, I don't see how it is moveable.

[jim murphy]

I guess I still fail to see how the rear clip will move/steer. I could see some movement with soft mounts in the rear, but with solid mounts and a solid ball joint up front, I don't see how it is moveable.

Apparently, it has been modified so you will have to fabricate what I mentioned earlier
to make a true suspension that was NOT there earlier.

Jim

[godwinmt]

Just as an update, Progress is slow but sure. The bearings for the rear axle came in Wednesday. I made new mounts for the rear subframe as the old ones no longer fit once the wheelbase was extended.

Cleaned the axle up with a wire brush and when I got the inner bearings mounted and the axle in, it spun beautifully. Mounted the sprocket, and ran into a major holdup. The collector on the bike was positioned a little awkwardly and was coming into contact with the chain when spun manually

Ended up solving the problem by picking up a 15 tooth idler sprocket which was attached to the bike frame. After mounting it up and picking up a half link to join the chain, the setup works beautifully. I'll be finishing up the rear axle tonight and then get ready to mount the rear subframe. I've got to run by the store tonight and pick up some radiator hose and possibly some fuel line, but overall it is coming together excellently (is that a word )

[godwinmt]

Got it running today!

http://www.youtube.com/watch?v=nHWHKtnxwJQ

[preform resources]

Hey Jimbo, what class would this car fit in,in autocross ?
Dave Craddock

[godwinmt]

If I get it homoglated it can run B mod, otherwise it's an A mod car.

It's essentially driveable and I'm looking forward to racing this weekend at the local autox event. I've got to do a quick repair to the shift cable tonight when I get a balljoint in from mcmaster, but other than that it's moving

I took it out over the weekend for some fun without the body, and well...holy butts is it fun and quick! I had some problems actually putting the power to the ground, but that's with very hard/old tires on a gravel road (yay for living in the country).

Couple pics

Driving it around the drive with the body off


Body set on in barn


Cockpit and shifter setup to the left under the wheel


Another exterior shot


I did have a question. What do most people run for seats in F500's?

[jim murphy]

For a seat in a cockpit, most people start with aluminum sheets and form them from the anti-submarining bump in the front under your thighs up to the back of the neck bottom (a firewall is required in addition to the seat). Two part foam finishes the shape and foam cushioning is added to help with the bouncing around - you don't want to move at all.

BTW, the butterfly steering wheel is upside down - flipping it will give you a little bit more clearance for your legs. The steering ratio should be as short as possible so that you can catch the car with counter steering when the rear steps out. This can be accomplished by drilling another hole about 1/2 way along the horizontal steering arm to the upright. The original slower ratio was for the much higher speeds in road racing.
A little toe-out (1/8") will help turn-in. Once you buy new R25's, do some testing to see what tire pressure (around 15 lbs) gives even temp's across (do a bunch of circles on asphalt/concrete to heat up the outside tires) along with the best negative camber for this as well. Bumps are going to be a REAL threat as you have no suspension which can send the car in a direction you do NOT want to go at speed.
You will quickly find out that too low of a final drive ratio will make the car in 1st/2nd gear virtually undriveable.

Jim

[godwinmt]

For a seat in a cockpit, most people start with aluminum sheets and form them from the anti-submarining bump in the front under your thighs up to the back of the neck bottom (a firewall is required in addition to the seat). Two part foam finishes the shape and foam cushioning is added to help with the bouncing around - you don't want to move at all.

BTW, the butterfly steering wheel is upside down - flipping it will give you a little bit more clearance for your legs. The steering ratio should be as short as possible so that you can catch the car with counter steering when the rear steps out. This can be accomplished by drilling another hole about 1/2 way along the horizontal steering arm to the upright. The original slower ratio was for the much higher speeds in road racing.
A little toe-out (1/8") will help turn-in. Once you buy new R25's, do some testing to see what tire pressure (around 15 lbs) gives even temp's across (do a bunch of circles on asphalt/concrete to heat up the outside tires) along with the best negative camber for this as well. Bumps are going to be a REAL threat as you have no suspension which can send the car in a direction you do NOT want to go at speed.
You will quickly find out that too low of a final drive ratio will make the car in 1st/2nd gear virtually undriveable.

Jim

Thanks for your help Jim! I'll flip the wheel ASAP! It was actually like that when I got the car so the PO must have done that.

I was actually looking into the 2 part foam bead seat kits and I think that may be something to do down the road after making a backer out of alumnum as you suggest.

The pitman arms were already shortened. That was actually the first thing we did to the car. We went from roughly 12 degrees of max steering angle to just short of 30 which has helped a lot.

We have a pyrometer setup at school we use on our school's autox cars. dialing in pressure will be something to do as soon as I get the new tires which will be about the time I head back to school.

One thing I want to ask, you say shoot for even temperatures all across. Granted these are street cars, but we've found that we have actually gotten more lateral grip when there is about a 20 degree gradient in temperature from the hotter inside to the cooler outside. Because of this we whipped up an excel spreadsheet to plot the temperatures and then set pressure based on the linearity of the line. Have you found this to be the same with open wheel cars?

Thank you again!

[jim murphy]

Thanks for your help Jim! I'll flip the wheel ASAP! It was actually like that when I got the car so the PO must have done that.

I was actually looking into the 2 part foam bead seat kits and I think that may be something to do down the road after making a backer out of alumnum as you suggest.

The pitman arms were already shortened. That was actually the first thing we did to the car. We went from roughly 12 degrees of max steering angle to just short of 30 which has helped a lot.

We have a pyrometer setup at school we use on our school's autox cars. dialing in pressure will be something to do as soon as I get the new tires which will be about the time I head back to school.

One thing I want to ask, you say shoot for even temperatures all across. Granted these are street cars, but we've found that we have actually gotten more lateral grip when there is about a 20 degree gradient in temperature from the hotter inside to the cooler outside. Because of this we whipped up an excel spreadsheet to plot the temperatures and then set pressure based on the linearity of the line. Have you found this to be the same with open wheel cars?

Thank you again!

The bead seat kits are pricey and two part foam is much cheaper - takes a garbage bag and a 2nd person to pour it in (gets really warm!). You don't want to sit on aluminum as it stains anything that sits on it.
You will have to try both tire temps approaches to see which one works best for you.

Jim

[zexel]

I think all autocross cars must have working suspension front and rear, though a small local club may let it slide. It sure helps the handling..........

[lancer360]

Jim is right, save your money and do a 2 part foam seat. Bead seats give much better impact protection, but since you are only going to be doing autocross, a 2 part foam seat will be 1/4 the cost and provide just as much support.

[bpimm]

Great project, any updates?

You will probably want to convert to a 4 link rear suspension at some point, the solid read and puck front will be hard to balance out. Does it still have the rubber puck in the front?

The 2 part foam seat is plenty good for autox.

When I built my car (1987 Red Devil + Hayabusa engine) I used GSXR 600 rear coilovers for the suspension. dual adjustable damper with about a 700 Lb spring for $30.00 new takeoffs on ebay.
They are working better than i expected.

Keep us updated.

[godwinmt]

Unfortunately updates are kindof slow at the moment. So far its been working out a couple of kinks with it which i'm confident I've eliminated.

The plan was to run in an autox a couple weekends ago, but on the shakedown run to triple check everything the night before, I let my brother drive it. Somehow he managed to break the throttle cable so it ended up not running in the race. The next race is this weekend, and everything has been fixed and nothing has happened in the nightly drives at home, so its game on.

I am looking over the next year at school to get a 4 link type setup designed for it.

It is still running the pucks, but most likely since it's running AM, once I get access to our school's corner scales I'll take some measurements and eventually convert over to a spring/damper setup. Thanks for the heads up on the gixxer takeoffs though, those sound like a great bang for the buck!

How big of a problem with wheelspin do you have with the busa engine? That has got to be the definition of verge of too much power

[bpimm]

To Much Power.... No such thing

I have it geared for about 125 MPH top end. With that gearing i can torch the tires in 1st, 2nd, and 3rd gears if I want to. for autox I launch in 2nd and I have not topped third yet, third is good for 82 MPH, been close but not quite. it has enough torque that on the faster events I rarely have to drop to 2nd. it pulls strong in third from about 30 MPH on up.

One note on the 4 link, Jim had said to put the front mounts up at the main hoop, this is how the F500's are built but they run a jack shaft up there also and that keeps the final drive geometry good. If you are running direct chain drive, then you would want to have the front pivots located at the drive sprocket to keep the chain geometry right.

My front pivot points are at the main hoop and I'm direct chain drive and the geometry is horrible, over 1" of length difference through the travel range, I handle it with a bad ass chain tensioner. you don't want to go that route.

The busa has a lot of power now but it is not enough to be able to run the max wings for AM, I will need more when I get to that point.

[godwinmt]

Very cool. This is currently geared for an 85mph top end which is more than enough regional events here.

Good to note on the 4 link. We had all sorts of weird ways to tension chains back on my FIRST robotics team in high school! I'll make sure to have the pivot at the center point though.

20 square feet of wings is a decent amount! I can see where the busa wouldn't have enough power once you get moving with it. Would something like a small turbo setup be an option? AM rules say nothing about it

[godwinmt]

Another question while we're on it. What are you doing for your rear axle? Are you still with the solid rear or have you gone to a chain driven rear differential like the FB's do?

[bpimm]

Yes a turbo is probably in the future, maybe big bore also. I figure i need 250-275 HP to push the wings to a top speed of about 70-80 MPH.

I'm still using the live axle from the F500. Plans are to go to independent rear, I snagged a low hour Quaife/powertech gear drive unit like the radicals use that will get me away from chain drive altogether.

Good luck at the race this weekend.

[godwinmt]

Thanks! Good luck with your build! I'd like to most likely keep the chain with mine in the future, but eventually pull an LSD from a honda FWD trans and make a sprocket to adapt to it. I've been big into honda b series engines, and something like the mfactory LSD for a 98 spec ITR would work great...take the sprocket and bore out the inside to fit where the FD gear would. I'm almost done actually with my CAD design of the rear suspension so I'll post pics of it in a few days.

[godwinmt]

Hmmm...looking back it doesn't look like the shakedown video from a couple weeks ago ever got posted. This was one of the first runs of the cart around home getting a few bugs/kinks worked out. The very end I ended up loosing the chain as the setscrews centering the axle walked out. That has since been taken care of. She will run this Sunday at a local autox event. I'll be sure to take video.

Video Link

[glenn cooper]

Looks like it's coming along real good.
I did notice one thing though; you mentioned the use of a half link in the chain.
AFAIK, these do not have near the strength of the other links, in which case you have a weak link installed.
Surely there is a way to get the chain tensioned correctly without a 1/2 link?

Good on ya for the initiative, sadly lacking in many folks in this day and age!

[godwinmt]

Yup, the half link is now gone

Took it to autox yesterday for the first time to actually have it out on pavement for the first time. It is definitely much more fun to drive than my street car autoxing! First heat went absolutely phenominal outside of plowing a few cones over. I did fight some understeer though which was curable with a little more right foot action

Second heat I launched great the first run and ended up bent the rear subframe where I extended it. It was a decently large design error on my part, but is easily curable this week. It did end my day early though, but nothing ever goes off perfect the first time out

Video of first runs

I had a great time and the car went over very well with the local crowd. Had a fellow racer pull up next to me in a blue Z06 asking some questions about it. Said he used to race one just like it in the 80's at Road Atlanta until he decided that it was too hard to get in and out of

[bpimm]

Sounds like you had a good time.

Watching the video, it looks like you are fighting under steer, check and see if you can soften the front suspension or change it so you can. With the solid rear you will need to induce body roll to unweight the inside rear tire to help overcome the under steer. like a kart chassis that uses chassis flex for the same purpose.

Looking good, keep the updates coming

[godwinmt]

Understeer was the big killer really only during corner entry. After applying power coming out of a turn, the rear tended to want to bounce a bit causing a few moments of oversteer. I believe it was essentially wheel hop from running too soft of rear puck (50A), but I'll worry about that when I get it put back together.

I don't have any pictures here at work, but I pulled out the subframe last night and have it cut apart to repair. There was about 10 degrees of actual bend in the rear subframe Luckily the damage was isolated to the extension piece I had welded in so after cutting that out, I'll be able to reweld it all up tonight and get a coat of paint on it for assembly Thursday night.

Oh, the R25B's came in last night as well Going to be much easier to drive on than the old tires. Looking at the goodyears, I was mistaken originally and the fronts are the 19.5x6.5s. The new hoosiers are an 18x7.5 which sould help out quite a bit with the understeer.

I'd also like to give a big thumbs up to John Berget Racing Tire for their epic wins of service! I called John up about getting a set of used R25B's to finish out the season Monday at 1:00pm and he got me setup with a set in about 10 minutes for $50 apiece. Said he would also throw in an extra with a small flatspot as a spare if I wanted to pay for shipping which was cool. Got all 5 tires at my door yesterday by 3:00pm...just amazingly fast shipping! I looked at the one that he marked as the spare, and for the life of me cannot find the flatspot so much more win

[godwinmt]

Thought I'd post an update...just had the first autocross of the 2011 season at Rantoul today and did very well. Last year was spent working out a few bugs, but I think I've finally got it most of the way down. cart ran great, and outside of not being able to keep any any heat in the tires with a codriver (35 degrees out + 20mph wind), and was good enough for 4th fastest time overall. Fastest time was set by a 997 turbo S which was able to put the power down

Here's a quick video of my last run of the day.

[jim murphy]

Thought I'd post an update...just had the first autocross of the 2011 season at Rantoul today and did very well. Last year was spent working out a few bugs, but I think I've finally got it most of the way down. cart ran great, and outside of not being able to keep any any heat in the tires with a codriver (35 degrees out + 20mph wind), and was good enough for 4th fastest time overall. Fastest time was set by a 997 turbo S which was able to put the power down

Here's a quick video of my last run of the day.

WOW!! I just spent the night in Rantoul at a Super 8 Motel while I picked up a new F600 Scorpion from Kenny Price in Dewey (5 miles west). Kenny sold his car building eqpt. to Leon Mitchell in Indianapolis and I got his very last car. Our latest F600 census is now at 24 cars with 8 already raced (www.eformulacarnews.com).

Jim