LocostUSA.com

Learning how to build Lotus Seven replicas...together!
It is currently June 23, 2018, 5:58 am

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 14 posts ] 
Author Message
 Post subject: Lotus Series IV
PostPosted: November 29, 2015, 12:14 am 
Offline
User avatar

Joined: March 30, 2011, 7:18 am
Posts: 1379
Location: central Arkansas
I found a nice article on the Seven Series IV here: http://www.simplesevens.org/anglocanadian/angloSIV.htm

Two of the pictures:
Attachment:
SIVPressRelPhoto1.jpg
SIVPressRelPhoto1.jpg [ 86.13 KiB | Viewed 2953 times ]


The whole body is fiberglass.

The front fenders extend all the way to the back, but they also point slightly down at front instead of aiming at the sky.

The undersides of the fenders - most of the side of the car - appears to be flat black.

The tail is much longer than previous cars.

The cockpit opening is also much longer

The rear fenderwell opening isn't round

It's not apparent from this picture, but the hood and nose are all one piece and tilt forward for engine access. The dashboard is also fiberglass and not flat. And the hood latches inside at the middle, apparently with an inside release.

and

Attachment:
SIVPressRelp5.jpg
SIVPressRelp5.jpg [ 146.43 KiB | Viewed 2953 times ]


note the exhaust travels along the side, then back through the body and out the back, instead of being a sidepipe. That may have been a legislative thing; many US states have had laws requiring the exhaust to exit some specific distance behind the last openable window, etc.

the windshield appears to use cast brackets instead of sheet metal

the battery is moved to the rear

the radiator is moved back behind the rack and pinion, and an oil cooler has been added

the usual S3 front anti-roll bar is not visible. And while the A-arms still attach in single shear, the upper wishbone looks very narrow at the base. And it appears to be using a trunnion instead of a ball joint

the chassis is MUCH different. It's noticeably shorter in front, and the back is triangulated differently. It's not readily apparent if there's a structural rear bulkhead; we see a long diagonal instead of the tube arrangement on earlier and later cars

the center spine is square on top instead of being half-round, and looks to be taller than the S3

I don't see any master cylinders, so I'm assuming it has floor-mounted pedals


The press release says, "increased leg room ... Europa concept double wish-bone suspension ... collapsible steering column ... extensive sound proofing ... hazard warning light ... glass fibre body shell, double skinned at cockpit sides and fully weatherproofed ... 165 x 13 Sport radial ply tyres ... 13 in. steering wheel ... ammeter ... two speed wiper ... screen washer ... heater ... rubber mats ... diagonal seat belts ... weight from 1102 pounds ... 7-1/2 gallon fuel tank behind seats protected by chassis structure"

The earlier cars used 15" tires as far as I know. The brochure for the 4 says "13" in several places.

From the description at simplesevens.org and the drawing above, it looks like the rear axle location was entirely different than the S3 or later Caterhams, using a four link instead of an A-frame.

My eyes always slid over the Series 4 cars. The styling is a product of its time, I guess, but it always looked like someone built the buck out of plywood and rounded the corners a bit before making a mold. For a dune buggy body to go on a used VW pan, sure. But at Lotus prices, I can see why they gathered dust in showrooms.

edit:
I found this drawing of an S4 chassis:
Attachment:
S4chassis.png
S4chassis.png [ 209.24 KiB | Viewed 2943 times ]

http://sevener.fr/articles_redac/Design ... 4_(Type_60).pdf&sa=U&ved=0ahUKEwjnh4Gf67TJAhWGLSYKHV21DME4ChAWCEQwCA&usg=AFQjCNEU4JK7_ie5BG40buHuiqotIfiBbg


Top
 Profile  
Reply with quote  
 Post subject: Re: Lotus Series IV
PostPosted: January 10, 2016, 7:08 am 
Offline

Joined: February 20, 2015, 12:04 pm
Posts: 281
Location: Cotswolds - UK
A few comments to expand on your post:

TRX wrote:
the usual S3 front anti-roll bar is not visible. And while the A-arms still attach in single shear, the upper wishbone looks very narrow at the base. And it appears to be using a trunnion instead of a ball joint

The entire front suspension was much more closely related to that on the Elan/Plus 2/Europa, with a front crossmember and suspension turrets not dissimilar to those used on the Elan's backbone chassis, and shared many components. Anti-roll bar was mounted low down and attached to the bottom wishbone, and yes, its the usual Triumph uprights with trunnions.

TRX wrote:
...I don't see any master cylinders, so I'm assuming it has floor-mounted pedals

The pedals were top mounted. They were carried the 'bulkhead panel' that you can see on your chassis diagram, on which you can see the holes for mounting the master cylinder.

TRX wrote:
...From the description at simplesevens.org and the drawing above, it looks like the rear axle location was entirely different than the S3 or later Caterhams, using a four link instead of an A-frame.

Yes, entirely different. The S4's rear suspension was even more conflicted than that on the 'normal' Seven, and relied on a big, squishy bush (the one marked '6000 bush' on the diagram below) to give some roll compliance against the fore-and-aft Watts linkages. The compliance from this bush led to some problems with axle tramp.

Image

A company called Sylva over here in the UK uses a similar arrangement (albeit with a Panhard rod instead of triangulated lower link for transverse location), much more successfully, by just relying on the small amount of compliance in the 'normal' bushes at the ends of each link.

And yes, the car was very much a product of its time and the dune buggy styling was quite intentional - VW-based dune buggies were extremely popular here in the UK, back then!

Contrary to popular opinion, and a little known fact, but it was commercially quite successful, though: it actually made a profit on each car built (whereas the Seven S3 made a loss on each car, for Lotus), and during its short production life it sold at a much faster rate than the S3 had. Apparently the S3 lost about £110 per car whereas the S4 made a profit of £150; 625 S4's were produced over a 2 year period, compared to 350 S3's over a similar period preceding it

It was killed off not by unpopularity, so much as the twin issues of Colin Chapman's desire to move the company's products up-market with the wedge-series Elite and Esprit, coupled with the closing of a loophole on purchase tax, which had previously exempted component cars in the UK, the loss of which made it commercially much less attractive.


Top
 Profile  
Reply with quote  
 Post subject: Re: Lotus Series IV
PostPosted: January 10, 2016, 3:15 pm 
Offline

Joined: August 11, 2012, 10:56 pm
Posts: 187
Location: Arizona
Very interesting - thanks for posting the info

_________________
* vsusp
* 5.0 442E build


Top
 Profile  
Reply with quote  
 Post subject: Re: Lotus Series IV
PostPosted: January 10, 2016, 7:37 pm 
Offline
User avatar

Joined: March 30, 2011, 7:18 am
Posts: 1379
Location: central Arkansas
Thanks, Sam!


Top
 Profile  
Reply with quote  
 Post subject: Re: Lotus Series IV
PostPosted: January 10, 2016, 9:02 pm 
Offline
User avatar

Joined: April 12, 2012, 11:56 am
Posts: 622
Location: Pemberton, BC
Thanks, Sam. Interesting.
Do you know anything about the sheet metal panels? From the picture, I can't tell if they were riveted aluminum, or welded steel. I'm interested in the welded steel option, for my next build (a Morgan 3 Wheeler replica). If I want to incorporate the body curvature into the frame, then the skin will have to be stressed, or the diagonals a smaller diameter. For aesthetics, welding would be a cleaner look. An example would be the JZR tub.
viewtopic.php?f=36&t=17840

_________________
Martin


My build log:
viewtopic.php?f=35&t=14520&start=0
My build video:
https://vimeo.com/143524140


Top
 Profile  
Reply with quote  
 Post subject: Re: Lotus Series IV
PostPosted: January 11, 2016, 9:43 am 
Offline

Joined: February 20, 2015, 12:04 pm
Posts: 281
Location: Cotswolds - UK
mgkluft wrote:
Do you know anything about the sheet metal panels? From the picture, I can't tell if they were riveted aluminum, or welded steel.


Well, they're welded steel on the Seven S4, I know that much!

The JZR is a nice little car, but remember that, being a three-wheeler, its requirements for torsional stiffness are much lower than those of a 4-wheeler.
My guess is that to gain sufficient stiffness just using single curvature, single-skin stressed steel panels, the steel would need to be relatively heavy gauge?


Top
 Profile  
Reply with quote  
 Post subject: Re: Lotus Series IV
PostPosted: January 13, 2016, 9:48 am 
Offline
Automotive Encyclopedia
User avatar

Joined: December 22, 2006, 2:05 pm
Posts: 5618
TRX, there is something wrong with your link.

I think it is a much better car, and not just because of the weather protection. The seats are molded into the tub also and it is much easier to install the engine and trans with the removable front upper crossmember. The frame is less rigid than the s3 but the glass body contributes to the rigidty. The sheetmetal was spot welded to the tubing.

The 4 link is actually two watts linkages mounted sideways.

Some were made by Caterham and by a company in NZ, but I forget who.

_________________
MV8

https://www.youtube.com/watch?v=Om3C1Ep ... D3E18BB447


Top
 Profile  
Reply with quote  
 Post subject: Re: Lotus Series IV
PostPosted: January 14, 2016, 10:57 pm 
Offline
User avatar

Joined: March 30, 2011, 7:18 am
Posts: 1379
Location: central Arkansas
Yeah, I tried pasting it three or four times and it never would "take." You can copy it and paste it into your URL bar and get there, though.

It's a fairly interesting design analysis of the S4.


Top
 Profile  
Reply with quote  
 Post subject: Re: Lotus Series IV
PostPosted: January 15, 2016, 10:55 am 
Offline
Automotive Encyclopedia
User avatar

Joined: December 22, 2006, 2:05 pm
Posts: 5618
If you delete everything after "pdf" it works. Great article!

_________________
MV8

https://www.youtube.com/watch?v=Om3C1Ep ... D3E18BB447


Top
 Profile  
Reply with quote  
 Post subject: Re: Lotus Series IV
PostPosted: January 15, 2016, 11:37 pm 
Offline
User avatar

Joined: July 29, 2006, 9:10 pm
Posts: 2907
Location: Oregon, usually
TRX wrote:
The press release says, " ... extensive sound proofing ... "
Well then take my money!

It took me a while to edit the URL (even with MiataV8's advice) for TRX's second link so here's what worked for me:

http://sevener.fr/articles_redac/Design_Analysis_of_the_Lotus_Seven_S4_(Type_60).pdf

I've always rather liked the styling of the S4--even simpler than the S3 and earlier models, and simplicity is the primary charm of the Se7en--and if I'd been one of the three lottery winners day before yesterday, I'd be looking for an S4 so I could own a Real Lotus.

Sam_68, thank you for pointing out the error of the S4-was-a-failure-and-nobody-liked-it legend.

PS--though I've never ridden in an S4, or even seen one in person, "extensive sound proofing" sounds a bit of wishful thinking.

_________________
Locost builder and adventurer, and owner/operator of http://www.kineticvehicles.com


Top
 Profile  
Reply with quote  
 Post subject: Re: Lotus Series IV
PostPosted: January 16, 2016, 10:57 am 
Offline

Joined: July 6, 2008, 11:15 am
Posts: 1049
Location: Cave Creek, AZ
Just getting the exhaust out the back of the car would have enough sound proofing for me.

Tom

_________________
Sometimes, I'm as confused as a baby in a topless bar.

My short term memory is absolutely horrible and so is my short term memory.

https://www.youtube.com/watch?v=sG16m2e4O6I


Top
 Profile  
Reply with quote  
 Post subject: Re: Lotus Series IV
PostPosted: February 19, 2018, 10:57 am 
Offline
User avatar

Joined: March 30, 2011, 7:18 am
Posts: 1379
Location: central Arkansas
Looking at some pictures, the front of the frame on an S4 sure *looks* to be less tapered than an S1, and the front of the chassis looks wider. I can't find any drawings of the S4, or even any pictures I can make a direct comparison with, though.

From what I've read the sheet metal panels on the S4 chassis were welded steel. I've wondered whether corrosion was an issue, from water getting into the gaps between the panels and the frame tubes, but I haven't found any mention of it.

The cockpit opening still looks longer than on the earlier cars.

Even though I think the dune buggy bodywork is fugly, the S4s are fascinating for some reason. I did find pictures of two S4s where the owners had junked the fiberglass bits and rebuilt them to look like S2s.


Top
 Profile  
Reply with quote  
 Post subject: Re: Lotus Series IV
PostPosted: February 19, 2018, 1:41 pm 
Offline

Joined: February 20, 2015, 12:04 pm
Posts: 281
Location: Cotswolds - UK
TRX wrote:
I've wondered whether corrosion was an issue, from water getting into the gaps between the panels and the frame tubes, but I haven't found any mention of it.


Yes, it very much was.

There's a book (now very rare and valuable) called 'Lotus Seven: Restoration, Preparation, Maintenance' by Tony Weale that covers the S4 in some detail, including the chassis design and restoration, but suffice it to say that it's a real rotbox in exactly the areas you've identified.


Top
 Profile  
Reply with quote  
 Post subject: Re: Lotus Series IV
PostPosted: February 19, 2018, 4:59 pm 
Offline
User avatar

Joined: July 29, 2006, 9:10 pm
Posts: 2907
Location: Oregon, usually
Sam_68 wrote:
Apparently the S3 lost about £110 per car...
But they made it up in quantity. :-)

I still like the S4. I think it has potential as a semi-replica DIY car...but then again, as my dad used to say, You can do anything you want, you just can't do everything you want.

_________________
Locost builder and adventurer, and owner/operator of http://www.kineticvehicles.com


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 14 posts ] 

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 2 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