Racing Seat And Seat Mounting

[rgh0]

For many years I have used the standard seat in my Elan S4 for racing, good enough from a driver location view point but a concern in an accident due to its lack of strength and 2 bolt mounting. I want to upgrade to a racing seat for added safety and even better location in high speed cornering (a very experienced racing driver friend of mine says a good seat is worth 10 to 20 HP in most cars similar to an Elan) and would like to know what people have fitted as none of the normal racing seats are narrow enough to fit into the seat well of an Elan. The only seat I have heard that fits is a "Cobra Imola" with mods to the wings or a TTR 26R seat.

My other concern is how to mount the seat. No good having a good seat, harness and roll cage if the seat goes through the floor. Dave Bean put a carbon fibre floor in his Elan to ensure the seat was properly anchored after he rolled his Elan once. I dont think I can afford that option but would like to mount my seat better than bolting it into 35 year old fibre glass. I have sketch up a number of design using various frames to connect the seat mountings to the chassis, door sill and roll cage but would like to know if anyone else has addressed this problem and what they did.

Rohan
Elan S4 FHC

[steveww]

Have a look at <a href='http://www.europaspares.com/' target='_blank'>http://www.europaspares.com/</a> they have some narrow seats for little sports cars like the elan and caterfields

[sotul86]

Hi I?m also interrested in this topic.

Was considering one extra bar in my roll cage, in front of seat connecting to frame and side protusion bar.
Something like this



Picture from <a href='http://www.racecar.co.uk/kelvedonlotus/gallery2.html' target='_blank'>Kelvedon homepage</a>

But still seat only in the two bolts in fiberglass

Surely some one must have done something in this area or thought about it??

[paros]

Race seat is problem and on my various race Elans when in England the best was not the 26R but Mallock as used in their race cars. Fits beautifully and is high enough at shoulders it can be attached to roll cage to stiffen the seat. I used a piece of steel sheet below seat going across from intrusion bar and bolted to chassis. Not perfect but as someone who had several crashes, I can only say it worked. I also spraed the load into as much of the floor as I could.
Biggest problem is that if you are taller than 1.85 then your head is higher than roll bar, thus need seat where yoyur backside is on the floor and not on cushion or padded seat. Thus shell seat such as 26R or Mallock is ideal.
Richard

[ernest87544]

Rohan,

Seat & belt mounting in an Elan is a vexing problem. I chose to build a tubular side intrusion structure for my Elan and mount the both the seat and belts to the steel backbone on the inside and this structure on the outside. There are photos of the tubular structure in the Roll Cage file along with yours. Photos of the interior with the seat in place can be seen at <a href='http://buffalotours.home.att.net' target='_blank'>http://buffalotours.home.att.net</a>. In the US we have several types of alumunum seats available and I believe they are the safest way to go.

Gerry

[rgh0]

Gerry and others

Thanks for the replys. I am still thinking about the options and your feedback has given me a lot of possibilities to work through. I need to get it sorted out though and stop procrastinating. Spinning in front of about 10 other cars as I did last weekend and sitting in the middle of the track facing the wrong way as they all managed to successfullly get past me sure focuses the mind of crash impact safety !!

Rohan

[type26owner]

Found a technical glitch with my plan to use Schroth Autocontrol Safety Restraints in combination with the original Elan seats. Schroth recommends against using them with any low back seat arrangement which does not keep the shoulder harnesses constrained laterally. Since my only purpose is to have a trackday worthy car and the fact the car offers nearly zero impact strength to the door area should I be concerned enough to replace the seats so the harnesses conform to Schroth standards? Without a complete roll cage, meeting this requirement seems rather futile. Should add that the shoulder harnesses on the driver's side is attached to the rollbar mounting and is laterally constrained about six inches behind the seat. Passenger's seat is positioned farther forward by about six inches to clear the original battery location. Opinions?
Keith

[rgh0]

Keith

Not sure about the version of Schroth belts you are referring to.
I use a Schroth Profi 11-6 ASM harness wth the standard seats. This is a FIA approved six point harness. and in the instructions they warn against fitting in a car with seats with no head rest or high back rest. However given the small distance in an Elan from the normal mounting point at the top of the rear tower to the seat I see no problem with lateral stability compared to having the belts go through suitable high back seat or head rest arrangement. The Elan arrangement is not that much different from a seat with the straps through holes at shoulder level.

In any case no other harness is going to be any better with the standard seat.

There are other aspects of Schroth instalation instructions that are also hard to meet. In particular the crotch strap monting point location and pull out stength specifications.

Competing in an small fibreglass historic car means some compromises compared to modern safety standards. The art is to minimise the issues and compromise in ways the limit the risk increase including how close to the limits you drive and how much wheel to wheel racing yuo indulge in.

Rohan

[type26owner]

Rohan,
The belts are a four-point harness with their anti-submarining mechanism incorporated in one of the shoulder harnesses so the crotch belts are unnecessary. Hoping to gain enough lateral support from the shoulder harnesses so propping myself up with a stiff right arm in not necessary anymore going around the quick left-hand corners in my LHD car. Controlling a slide with my left hand only at 100+ mph is exciting though! The downside is it's also extremely fatiguing.

Have you derived a seating arrangement which better suits the needs of full blown competition yet? Love to see a picture of it.
Thanks,
Keith

[rgh0]

Keith

The ASM device while helping prevent submarining and also reducing head and neck loads does not totallly replace the need for a 5 or six point harness in an Elan IMHO.

The problem is if you tighten up the shoulder straps to hold you firmly in place for competition the lap belt is pulled up to high. The only way to prevent this is to use a crotch strap 5 or 6 point arrangement or move the lap belt anchor mountings further forward which is hard to do without fabricating a new mounting plate that carries the load back to the orginal seat belt mounting or roll cage. When you move the lap mountings forward you end up with a less effective overall belt arrangement that I believe will suffer more than desirble forward movement in an accident.

The basic seat and mounting arrangement I have come up with is as follows

1. Fabricate a shallow U shaped tray of suitable thickness Aluminium alloy the width of the current seat base and thus a light push fit into the seat well width.
2. The sides of the tray will pick up the side mounting points of any competiton seat narrow enough to fit inside the seat well and thus inside the tray edges.
3. The tray will extend backwards far enough for the sides to also pick up the inboard and outboard lap belt mounting points which will also tie into my lower roll cage mountings which pick up the same points.
4. The front of the tray will pick up the original seat mounting bobbins in the floor
5. The front and rear inside and outside of the tray floor will be bolted through to the body floor and chassis flange using the holes that exist for the original seat runners.
6. The front outside of the tray will have some yet to be finalised arrangement to pick up the steel frame inside the door sill.

If I do all the above properly I am confident the tray and a competition seat bolted to it will stay in the car and stay fixed relative to the roll cage and seat belt anchorages. I also do not drill any extra holes in the body and the total arrangement is reversible back to standard easily.

I have not chosen a seat yet but any seat narrow enough to fit in the car can be used. A local maker of Lotus 7 style clubmans ( Elfin cars ) has a suitable competiton seat at a good price I will probably use. I will post some photos when I get to cutting metal on this project. Currently my time going on building up my second competition engine and gear box and doing some front suspension and sump / oil pickup modifications.

Rohan

[type26owner]

Rohan,
Yep, am aware of the lap belts' required positioning and will do the first fitting of the belts tomorrow. Hoping the original belt attachments points relative to the seat being positioned at the end of travel away from the pedals will help in that regard and the vector will be alright. If it's not okay, then your idea of adding a structural floorpan and a properly supporting new seat is the way to go. My I suggest the sheetmetal be made of stainless steel rather then aluminum. For a stressed floorpan with out of plane forces being applied it turns out as a first order approximation to get the same stiffness you must use the same total weight of material whether aluminum or any steel. This is because their densities (weight) are roughly in a ratio of 3 to 1 and so is their modulus.

Was pondered adding a flange to the original seat which wraps around below my right arm and laterally supports my chest. Chances are the seat frame is not sound enough to withtstand that type of added torsional load. Bad idea.
Regards,
Keith

[type26owner]

Rohan,
Was just under my S2 car figuring out how to attach a removable diagonal brace to my new rollover hoop to the passenger's footbox area of the chassis. While under there I noticed the fiberglass floorpan in not flat under the seats. It has a raised section about the footprint size of the seat which slopes up towards the front to stiffen that area. Any metal pan insert which installs from the inside is going to have to match that contour and complicate the fabrication considerably. Dratted again but still doable with great effort. Maybe a better approach would be to install a stiffening structure from the underside.
Regards,
Keith

[rgh0]

Keith

I thought about a plate underneath and then brackets inside that bolted through to the plate. May be easier to fabricate as you say. I you go the flat plate underneath route you need to make up a few brackets for inside the car as well.
eg
1. To connect the plate to the roll bar bottom mounts and seat belt mountsat the rear
2. To connect the seat to the plate.
3. to connect the front outside corner of the plate to the door sill truss.

In addtion the plate can pick up the the inside chassis flange and the original seat mounting bolt bobbins in the floor
I think either option will work you just end up with lot more holes in the floor if you go the outside plate route.


Rohan

[elandoc]

Hi Rohan,
A fascinating problem. There's a chap (forget who) from NSW who was at Lotus 2003 who had moulded up his own seats - I think he had a racing +2 - but they were very snug and stiff (and light). He'll probably bring it to Lotus 2005. I modified my seat to take a crotch strap and bolt the crotch and lap belts under the floor through a duralium plate that locates on the chassis inboard and the sill out board, but there's a bar through the sill (Safety Devices cage). I had a big off in Targa this year, smashing the floor over a culvert, and it all held together beautifully. The standard mounts are dangerous, allowing the lap belt to ride up and rupture your spleen or liver in a big one. My lap belt runs almost vertically, over the bony part of my hips - I can run the harness very tight and not get uncomfortable.
Patrick

[rgh0]

Hi Patrick

I read about your Targa exploits I hope the damage was not to bad

The guy with the plus 2 is Keith Edwards. I will look closer next time I see his car to see how he mounted it.

My seat project has taken a back seat ( sorry for the pun) to other jobs in recents months including trying to finish off my spare engine and gear box build.

I have found a local guy ( who is a lotus club member) who makes seats that are approved for things like the Elfin clubmans and cobra replicas. He can make one that will suit the Elan together with any mounintg frame I need. Once I get a little spare time and cash I was going to work with him on the detailed development.

regards
Rohan