Seat Belt Mounts

[EuropaTC]

Hi folks,

I thought I'd post up some photos of the latest "ohgeezwasIrelyingonthat" discovery.  I'm sure some of you folks have met this before but if you haven't, it's food for thought.

I've decided to fit inertia reel belts to my car so I can enter the modern world like you guys over there, and made a sobering discovery along the way. The photo shows the LHS sill mounting point for the seat belt, or rather what's left of it.  I don't want to be too alarmist because I think it would still have held should it ever have been used in anger, but it clearly isn't to the OEM design spec 

It was only held by 2 x 1/4" bolts, both of which sheared as soon as a spanner went near them. The rest just turned in the body because the mounting plate had rusted away completely and had to come out by angle grinder. There's not a lot else to say other than I'll be needing some steel plate this week.....

Tell tale sign - grab hold of the seat belt and pull vertically. If you hear gentle creaking and falling rust, you have a problem. (or "opportunity" as the positive thinkers would say    )

Brian

[BDA]

Yikes! I'm glad you didn't have to rely on that! It a good thing you decided to upgrade your belts!

Have you bought you new belts yet?

[Bainford]

Well, I guess the up-shot is that it is much lighter then original. 

[EuropaTC]

 

Well, as Colin always said, "add lightness" and when you see how much lightness I've added there I'd clearly be up for "employee of the month" ! 

Yes BDA, I've bought a set which claim to be able to operate the click mechanism at any angle so I'm hoping to have some flexibility in how they are mounted. It was Joji's comment about how robust the top mount was that got me thinking, but it's early days yet.

I've just finished making a replacement sill mounting plate today so once that's in place I can see how to put it together.  I don't think the seat belt project will be of much interest to you guys as your cars already come equipped, but it might be useful for any UK guys on the forum.

Brian

[Grumblebuns]

The sill plates may be the same for federal and non-federal TCSs. I took a look at mine on a spare TCS body and although corroded some what, it was still in one piece. FYI, the dimension is approx. 3.5"x 16" and appears to be secured by a couple 1/4" bolts and the main bolt for the seat belt. Although it is simply a thin piece of sheet metal, I'm sure that an engineer did the calculations so that the minimum safety requirements were met for the time. Looking at it, it really doesn't give you a warm fuzzy feeling, in other words, just don't get into a front end accident.

[BDA]

Don't get in a T-bone accident either! Thankfully Chunky protects the valuable frame in that event with replaceable driver or passenger! 

[jbcollier]

The S1 had a length of substantial angle iron as an outer seat belt anchor and jacking point.

[EuropaTC]

hmm, going off those measurements they might have changed plate design then.  Mine is about that length but deeper and an inverted "L" shape. It had 4 x 1/4" bolts along the top, the main seat belt bolt  and then 2 smaller bolts which go through that outer panel under the sill which is riveted to the floor. My problem seems to have been that with the metal held between the outer sill/floor it's let good old English rain in there to steadily rust the base away.

Properly constructed I think it'll be ok, or rather the breaking strain will be more than a passenger could take from the seat belt restraining force.   It's a large area of steel spreading the load over a fairly rigid fibreglass section and should it try to move vertically the horizontal part of that inverted "L" shape will hit square on the door shut panel over it's length.

The main bolt had the nut welded to what looked like a 1/8" reinforcing plate on the back to prevent it distorting locally and bending. It doesn't look as reassuring as thick plate but I can see how they've arrived at it.

[EuropaTC]

Hi folks,

I know this is probably old news to some folks, but it's mightily impressed me so I thought I'd post up a couple of shots of the RHS mounting plate which turned out to be in even worse condition than the LHS.

The first photo shows front & rear of the plate as removed. It really was like this, I haven't pulled off any steel to make it look more dramatic, this is what was sitting in the sill area and holding my seat belt in place. From inside the car there was no hint of the extent of corrosion, all the interior bolt heads were there and weren't even looking rusty but they just rotated as you tried to undo them because the steel behind was missing !

The second shot is the old & new plates to give you some idea of how much was missing, and the third shot is the LHS plate installed in the car.  I used dome headed stainless bolts instead of rivets for the lower two points which I think looks neater from outside. (the plan is to replace all the old rivets over winter)

I know I'm probably laboring the point but the extent of rusting has really surprised me and I think the message needs to go out to check these mounts unless you know for certain that they are good.  The final shot is from the rear wheel arch with the protecting plate removed to give you some idea of how easy it is to see these things. I used a knife blade between the outer sill and floor joint to scrape it clear of rust before replacement, so if you tried the same and get flakes of rust falling down, you need to investigate !

Brian

[jbcollier]

The S1s are much more robustly constructed.

[BDA]

Brian,

Are you able to reach in with your hand through the gap in the body in front of the rear tire to attach your pieces (terminology is eluding me!!) or do you have to drill out the rivets under the doors and spread the pieces?

[EuropaTC]

BDA,

I drilled out 3 rivets and with hindsight need only have drilled out the two rivets which were holding the plate at the bottom. (or not as in my case    )

This is actually a very simple job to do once the rear wheel arch protector is out of the way.  All the bolts have captive nuts welded onto the mount plate and although it looks difficult the plate slides in at an angle with the base going into the gap between the floor/outer sill where the two holding rivets have been removed and protruding outside. Then you just grab and drag it into place.  I used a small screwdriver to lever & hold it whilst getting the first bolt in then it was a minute's job.  It's easier to do than describe !

It's all back now, seat belts in place and now I know why Lotus mounted the reels so high up because  they won't fit anywhere else !  Well, not if you want any seat adjustment that is.  Just some carpet to glue back & bolt the seats in tomorrow and the "morning's job" (started a week ago) will be finished.....

Brian

[BDA]

That's great, Brian! Don't forget to post pictures!

[TCS4605R]

I made new seat belt anchors for my 74 TCS.  The old ones were rust dust.  There is a picture of it on the old Yahoo Groups site in the Photos Section under '4605R' named 'Outside Face - Outboard Seat Belt Anchor'.  If you can't get a view of it there, let me know and I will email it to you

Tom

[EuropaTC]

Hi Tom,

Yes, I do have access to the Yahoo group although I rarely post there, so I found your photos.  I did wonder if the plate was originally a rectangular shape and your shot confirms that.  Going on the oxide jacking between the outer sill & floor joint mine was only held on 2 rivets which is the reason I cut away the lower edges.

I've got to say that restoration you show has incredible attention to detail. One thing you can be sure of is that Lotus wouldn't have paid as much attention to painting the underneath & wheel arches as you have. I'm not even sure mine has any paint underneath apart from the wheel arches.

For anyone in the UK contemplating similar ideas, I've added a photo of the current installation. It seems ok, I'll live with it for a while and post up if any more changes are needed.

In the end I decided not to mount the reel in exactly the same position as the OEM ones for two reasons; firstly the detailed instructions with the reels indicated that a pull at 90deg was needed to lock the belts (so they wouldn't have operated "at any angle" as originally advertised    ) but more significantly the steelwork holding the reels in place is noticeably thinner than the pictures Joji posted. I had concerns that mounted in the same manner the steel would buckle under load, and if that let the reel break free you can imagine that's "game over" time.

I lost a very small amount of rearwards seat adjustment, probably less than an inch, so it doesn't concern me that greatly. The angle of the belt retracts easily and slips nicely away between the seat bolster & carpet, I pulled it out of line here so you can see how the reel is mounted.  Two bolts, above & below with the belt guide also mounted on the top bolt and taking all of the forwards loading. Hidden away is a steel reinforcing plate to ensure that the thin steel is under shear & not bending loads as in the sketch.

Brian