Lotus 38 ish Replica

Ben

New Member
#1
Hey all,

It was suggested by another member here who I bought a transaxle from that I post the progress of my build. No its not a GT40. I want a GT40. I just can't afford a GT40. And as prices climb like crazy I couldn't even afford a cigar shaped formula ford from the era, which I had been saving and shopping for for a while.

After autocrossing a 1970 Lotus Europa with a fuel injected engine swapped in, and then road racing a Formula 500 car, I realized not only had I completely disassembled and reassembled a car countless times, but also fabricated a lot of of replacement parts on the chassis's themselves. Plus I had come to love just how much ISN'T there on an open wheel car. So being a more than a little nuts I decided to build a secondary dream car to the GT40, and set out to build a kind of hybrid between the 1965 Indy winning Lotus 38, a formula 5000, and well a lot of F1 cars from the era that have one or another engineering solutions that I like.

If you want to know just how crazy I am: https://www.youtube.com/watch?v=DoSnoayLuIM

I'm just building the car to autocross with my local club as a for fun thing rather than to compete. Its not built to any current SCCA regs, and I'm not trying to pretend its original. I'm making it safer than an original (though that's not saying much) but there are certain things I'd have to change if I wanted to road race this thing around here.

I'm using a ford 5.0 engine with an Audi 016 gearbox. I grew up restoring classic Mustang's so I'm very familiar with the Windsor block. I'm not starting out with webers or fuel injection, just a 4 barrel for simplicity's sake and at a weight of 1,200lbs with fuel and driver, no matter what I'm going to have more than enough power to scare the crap out of myself.

From the rear bulkhead to the front suspension the car is an aluminum monocoque. Mostly 16 and 18 gauge 6061 T6. 2024 would have been more correct to the originals, but I live very near the ocean and was worried about corrosion.

The front suspension is mounted with a steel tube sub frame, and another steel subframe is employed at the rear for the engine and rear suspension. The rear subframe was a compromise I made for both longevity, and ease of modification. That and having to support the audi gearbox behind the axle shafts rather than in front like a Hewland or ZF gearbox would have been in one of these cars originially was a problem that steel tubes quickly solved.

The front suspension is Mustang II spindles, granada discs, and rocker arms from a Reynard Formula Ford.

The rear suspension is just fabricated from swedge tubes and using 94 Cobra Mustang hubs.
 

Ben

New Member
#2
Here is how I made the design. I made it first on graph paper, each square equalling an inch in real life. I read that this was a technique used in the 60's as it could help you determine where your weaknesses would be.
 

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Ben

New Member
#3
Then it was just a matter of translating each paper component to sheet metal. . . and drilling several thousand rivet holes.

I should say that living near Laguna Seca I get to see a lot of the original cars, including the Indy winning lotus 38, in person, so I've got detailed pictures of them inside and out. Plus books on Lotus designs, the Haynes Manual series on famous race cars and a book by Len Terry (who designed the Lotus 38) on building race cars all brought me from wondering how the heck these things were made to where I am now.
 

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Ben

New Member
#4
The engine seen in some of these pictures is a mock up block. I have the engine for the car, but its not all together yet. and a foam block that weighs 10lbs is a LOT nicer to use when locating the brackets for engine mounts.
 

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Ben

New Member
#5
The nose is fiberglass and still needs to be smoothed out, but I'm tired of itching so I'm putting that off for right now. Next up will be mounting the gearbox, steering rack, and doing some electrical work before I paint the car this spring. So far its been 7 months since I started fabrication.
 

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Mesa

Active Member
#6
That's a hell of a piece of work you have going there. Cool!
I tell you what. I'll make you a nose cone and finish it all ready for paint if you make me a copy of your chassis :)

I'll even deliver it over the hill for you.....what a deal.

Didn't I see an ad for a transaxle from you somewhere?
 

Ben

New Member
#7
That's a hell of a piece of work you have going there. Cool!
I tell you what. I'll make you a nose cone and finish it all ready for paint if you make me a copy of your chassis :)

I'll even deliver it over the hill for you.....what a deal.

Didn't I see an ad for a transaxle from you somewhere?
Oh man! Where were you 4 attempts at making a nose cone ago!?!

If I could, I'd make my living building stuff like this. Of course I'd probably go broke even before someone sued me for making something so unsafe.

I haven't sold any transaxles, I just bought the one I'm going to use a couple weeks ago.
 

Jack

Bronze Supporter
#8
That's a hell of a piece of work you have going there. Cool!
I tell you what. I'll make you a nose cone and finish it all ready for paint if you make me a copy of your chassis :)

I'll even deliver it over the hill for you.....what a deal.

Didn't I see an ad for a transaxle from you somewhere?
Better stick with what you're doing Rob, Time = money ya know!
R&D is redo and do again. I'm sure you've experienced that!
 
#9
Wonderful!!! During the past 2 months I've been gathering all the photos (and rebuild photos), scaled drawings, and even models that I can find of the Lotus 49 for just such a project for an upcoming retirement. I've got billions of questions!

Please, post away.
 

Ben

New Member
#11
I'm no expert, but I can let you know what I did for any given part and why. Hopefully I'll be test driving mine in ars time or less and will have a better idea what works and what didn't. If you're planning a 49, check out this guy:


Are there kit car companies for Lotus 25-49? - LotusTalk - The Lotus Cars Community


Wonderful!!! During the past 2 months I've been gathering all the photos (and rebuild photos), scaled drawings, and even models that I can find of the Lotus 49 for just such a project for an upcoming retirement. I've got billions of questions!

Please, post away.
 

Ben

New Member
#14
Here in Santa Cruz, the weather has taken a particular pattern where it rains on any day that I will have some free time. However, if I'm at work all day or staying home with my kid who's been sick, its sunny. So progress has been slow, and though a lot of work has been done, much of it isn't ready for pictures yet. I've also been dealing with a number of clearance issues that aren't a big deal but change a task from simply bolting something in, to doing minor surgery and rewelding and THEN after a few failed attempts, getting to bolt whatever in. All of this could have been avoided if I had ALL of the parts for the car before I built the frame so I could see if there were any unexpected clearance issues, like the angle on the top of the shock being less steep than I had seen on vintage racers and thus gets in the way. But if I waited until I had everything, I still wouldn't have started yet. :)

The biggest issue has been that I designed the rear of my car to hold a Renault UN1 gearbox, but at the last minute switched to an Audi 016. I had left myself a little extra length so it fit in longways well enough, but the Audi is lower behind the bell housing where the Renault starts to come up. This all meant I had to cut out the bottom of my frame in the rear and lower it. It kind of sucks because as simple as it was, I'd much rather have designed it properly to begin with with a little more elegant solution, but as is it was just some cutting and welding and folding some aluminum under it. In the end I got the transmission mounted (yes my mounts could look better, but I've got a surplus of some material here and have run out of others and am trying to keep this project to a only mildly inflating budget).
 

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Ben

New Member
#16
I did the engine height with a boss 302 style pan which is roughly the standard shape of any small block ford pans. I intended to cut a hole on the floor under it where the drain plug is, but the clearance was so tight I cut an opening (and reinforced it) for the lowest part of the whole sump. That way I'll get a little better cooling on the engine too. Though had I realized how low the output shafts are on the Audi box, I may have raised everything a quarter inch and not had to cut a hole. But it's all comprises, one way or the other.
 

Jim Craik

Lifetime Premier Supporter
#17
Hi Ben, great project. So you are a Santa Cruz guy, I love that place, we are just up the road in Los Gatos... one day I would love to check out your project, do you ever go to the Canepa open house?
 

Ben

New Member
#18
Strangely, I haven't made it to a Canepa open house yet. It seems like for the past 5 or 6 years (that I've been aware of them) I always realize the event is happening hours or a day or two after its over. But if you're going to one and give me a heads up, I'd make a point of making it.

And you're welcome to check out my project, as long as you don't mind me drooling over your GT40 :)
 

Ben

New Member
#19
No rain today! Got lots done. I relocated the lower mounting location of the front shocks to get a little lower ride height and lessen the angle the shocks ran at so they wouldn't hit the rocker arm, installed the shocks, put the steering rack in, and put the electric fan on the radiator before putting that back in.

Man, typing that out doesn't sound like much, but I worked pretty fat for 8 hours, and I'm exhausted now.
 

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