One of my better decisions

[Timothy Keith-Lucas]

When it came time to reassemble my Seven, it occurred to me that it had been a long job of drilling out blind rivets to remove the panel between the firewall and the top of the instrument panel, and that it had been necessary in order to access the rat's nest of wiring behind the panel. No way I could see what was going on from the bottom. So, I substituted steel 8-32 rivet nuts for the aluminum blind rivets. Good move.  I no sooner had her together than I started having problems with the 63 year-old wiring. The turn signals and that horrid Lucas $160 turn signal switch failed, the sidelights partially failed, the brake lights went dark -- everything started falling apart. The Dark Knight said get home before dark, and he meant it. So, off came the entire panel with the windscreen still attached, I ran new wire, and today the assembly does back on.

 

 

[EdWills]

Hi Timothy.  Just my take on this, but if I understand it correctly, you are referring to the scuttle - which is the shaped aluminum section that holds the windscreen and the wiper mechanisms and wiper arms/blades?

 

I see that your scuttle does not have a flat aluminum firewall sheet permanently riveted to the front of the scuttle as designed by Lotus.

 

Lotus did not intend the scuttle to be riveted or held to the top of the dash tube by any means.  On most? Unirad constructed Series 2 and Series 3 chassis frames, it was held on to the top of the chassis using 1 threaded bolt welded into the top of the frame.  The scuttle was then held in place by a washer and captive nut either side.  Later Arch frames incorporated 2 bolts either side, and Arch/Caterham specified a metal channel section to fit over the bottom section of the scuttle to snug it down over the studs and on to the frame using 4 washers and 4 captive nuts.  

 

Some owners discovered that the hole in the scuttle through which the oil pressure tube, water temperature mechanism, and speedometer cable (at least as applied to my l.h.d. 1969 Series 3 Unirad built Seven), just above where the steering column exits, caused problems when the scuttle had to be removed.  The scuttle was modified by some owners to join the steering column slot to the hole therefore allowing the scuttle to be removed more easily without disturbing the 3 gauge connections.  A rubber grommet would still be used on the 3 connections, but would easily slide out of the slot as necessary.  The only other items to be unbolted from the scuttle for removal would be the wiper blade mechanisms with their tubes still attached.

 

Many scuttles have press studs riveted or bolted into the scuttle to allow the tonneau cover to be attached, but - as relating to my frame - they were not attached to the dash tubes.  

 

I have found that my replacement scuttle does sit a tad too high when loosely placed on my frame, but when bolted tightly with the windshield unit in place, it should sit correctly on top of the curved dash tube. Best.  W.

Edited October 30 by EdWills

[Timothy Keith-Lucas]

Wow! Thanks so much for responding and telling me about it. 

 

That's really odd. Mine is a flat "U" with the windscreen brackets bolted through. The front edge of the scuttle is turned down so it overlaps the firewall. No plate. The turned down front edge was riveted to the fire wall in a string of about twenty blind rivets. The after edge is rolled, and then was riveted to the round frame member that also supports the top edge of the instrument panel. Not as many rivets this time.  There is no facility for easy removal of the scuttle. The stems for the wipers come up through the scuttle in front of the windscreen, but the motor and arm are anchored separately to the instrument panel. 

 

My S2 America was factory assembled and imported to the US in 1962. I have no reason to believe that the scuttle was ever removed after manufacture. The other oddity is that it's an "America" but has a right hand steering wheel. I can see how owners would have complained and asked for a way to remove the scuttle. You really cannot access the wiring from below.  

 

Well, I had the same problem they had, and solved it by substituting rivet nuts and screws for all those rivets. It works - I just put it back in place a few minutes ago.

 

Apparently, I've got a somewhat odd S2.

[EdWills]

Hi Timothy.  I think I see what you have done.  My scuttle has 47 Monel rivets (spaced at approximately 1 inch apart) that connect the vertical firewall panel to the 'U' shaped scuttle front.  Each rivet has a steel washer fitted (on the opposite side of the sheets to the domed head) that the pulled stem of the rivet sits against.  The scuttle is not a structural component, but where ally to ally is riveted together, a washer on the opposite side to the domed head of the rivet of the 2 pieces to be joined is good practice, and Lotus and Arch seem to have followed this method in most instances. This is the same practice used by Lotus for the structural floor under-tray and prop shaft tunnel riveting method.  The vertical firewall also has the starter solenoid installed, and the choke cable pokes out of a hole beside the solenoid unit.  The battery clamp shown in the pic. for the Exide battery was used on some Series 2 models and more so on the Series 3.  The vertical firewall slots into a 'U' shape formed in the horizontal firewall panel that the battery sits on.

 

My appreciation to John Watson for the photo of a LHD Series 3 Seven engine compartment. In this rather grainy photo reproduced from a Lotus ad, there are quite a lot of rivets on the scuttle firewall. W

Edited October 30 by EdWills

[IamScotticus]

I have drilled out my scuttle rivets as well, for ease of access., on a previous scuttle.  I have a newer one on now, and intend to do it again.

When I can, I would like to replace the firewall with a new piece of a thicker gage sheet.

In that picture, LHD S3 has indicators under the headlamps whereas a RHD S3 I have seen does not.  I am thinking these were USA DOT compliance additions.

On the S3 photo, I count 24-25 rivets.  My scuttle has 24

Edited October 31 by IamScotticus

[Timothy Keith-Lucas]

So, I'm not alone in having the scuttle riveted to the top edge of the firewall. She's back together, will hit the rod in a few days, and going to a friendly local car show in a week.

[7Westfield]

pre-lit Westfields also have the scuttle riveted to the vertical panel, with a lot of rivets.  The vert panel is tucked under the back edge of the horizontal shelf and riveted as well.  Would be PITA to remove scuttle assy.

 

I'm making a new dash panel, to move things around a bit, and remove unused switches, etc.

How is the dash mounted in a S2/3?

[MV8]

Many rivets with exposed heads. Not obvious on the newer cars.

[7Westfield]

1 hour ago, MV8 said:

Many rivets with exposed heads. Not obvious on the newer cars.

what I figured...

mine was sheet metal screws, I'm switching to rivnuts

[Timothy Keith-Lucas]

Rivet nuts certainly will last longer than sheet metal screws. Allow me to recommend the steel ones - it's too easy to spin the aluminum ones with just a tiny bit too much torque on the wrench. I set my drill (not my 1/4 inch impact driver) on low torque and chase the threads with a tap if I run into resistance.

[EdWills]

On 10/30/2025 at 8:37 PM, IamScotticus said:

I have drilled out my scuttle rivets as well, for ease of access., on a previous scuttle.  I have a newer one on now, and intend to do it again.

When I can, I would like to replace the firewall with a new piece of a thicker gage sheet.

In that picture, LHD S3 has indicators under the headlamps whereas a RHD S3 I have seen does not.  I am thinking these were USA DOT compliance additions.

On the S3 photo, I count 24-25 rivets.  My scuttle has 24

Hi Scott.  Most of the LHD and RHD Series 3 cars that I have seen were fitted by Lotus with the amber Lucas L691 signal lights mounted on a bracket fitted directly under the headlamps (as per mine and other Series 3 Sevens that were imported into the city where I live).  Lotus attached the amber signal lamps to the side of the nose cone on the 13 or so Twin-Cam cars (all RHD except 1), and possibly some owners chose to do the same?  Photos on https://simplesevens.org will show how Series 1, 2 and 3 cars are equipped.  Also Tony Weale has a number of photos of how the lamps were mounted. (see page 111 for example of a Series 3 RHD).

 

My scuttle came from Arch after the Caterham take-over (I have no photos of my original unit unfortunately), so possibly Arch may have followed suggested aircraft practice and placed the pop rivets at the recommended spacing (roughly 1 inch apart for a 5/32 inch rivet  @MV8?).  I don't think that Lotus were practising 'add lightness' by only providing 23,24, or 25 rivets on Timothy's or your scuttle Scott, but maybe cutting costs because, as noted, the scuttle is not structural?  Also, if an owner wishes to keep the firewall and scuttle in one piece, it does make it stronger to handle to remove and replace and it keeps its shape better this way to avoid having it buckle. Only the hole above where the steering column slot is located needs to be modified to join the two up. (see: 'where can I get a Series 2 nose cone by @Bill.  His scuttle appears to have the modification I am referring to).  In any event, to remove the scuttle without a firewall attached, you still have to unbolt it from the frame, and remove the wiper mechanisms.  With a scuttle that is kept intact, the choke cable also comes off with the scuttle, after unbolting the end from the carb(s).

So naturally, whatever works best for you. Cheers, W.

 

Just a P.S.  Just read an article from the 1980s by a Lotus Seven racer in the U.S.  He described the twisting that an original (unmodified) Lotus Seven Series 2 frame goes through in a race situation, and the stresses placed on the frame, ally body, and rivets.  I would have to defer to @MV8 to advise if Arch - with my scuttle at least - were trying to make this body part more structural?  With double the amount of rivets than required by Lotus, double bolt and nut fixing on each side of the chassis, and a strong channel piece to cover the area of the scuttle that bolts to the frame, possibly Arch have attempted to provide some structural support to the top of the chassis. I wonder though, how much extra it would provide?  W.

Edited November 1 by EdWills
P.S. added

[Timothy Keith-Lucas]

My guess is "not much." My reason is that the front of the scuttle attaches only to the sheet aluminum fire wall - there is not a frame member at the front. That's a lot of opportunity to flex between the frame member at the top of the instrument panel to the bottom of the fire wall.