I was wondering if anyone can comment on the use of sill stiffeners.
They are sold by various companies like Monocoque Metalworks (https://monocoque-metalworks.myshopify.com/collections/e-type-sill-panels/products/complete-hidden-subframe-kit-sill-gussets-hd-tubing)
or Martin Robey and perhaps others…
Are they really needed? Do they improve the stiffness of the body?
Tadek
Looks like a pretty good deal, and if Chuck says they work, I believe him!
I have great respect for the work done at Monocoque Metalworks but imho the real question is “are they really needed?”.
I’ve read the info on the site and I can detect only three specific reasons for the mod beyond making the monocoque extremely stiff, and those are
Conspicuous by its absence is any claim that it improves handling, although it is implied by reference to improving stiffness of the anchor points for the IRS trailing arms.
How many sound, rust-free OTS cars display chipping at the door shut panels? I submit the answer is none. Chipping is a sure sign of damage in the B-post and rear sill stiffener, primarily corrosion.
Is there a need to strengthen the jacking point if there is no rust damage in the sills, floors and crossmember? I submit there isn’t. Mine work fine just the way they are.
The mod arguably, and logically, makes the car safer, and that might be the only true justification for it, but without crash testing it’s all theory.
I considered the mod when I did the rotisserie shtick and decided it added coachbuilding complexity, and weight, with no real, documented benefit.
Finally you need to ask yourself if this particular rectangular-tube mod is beneficial then why don’t the best in class restorers, like Classic Showcase and RM seem to offer it?
Given how interesting the question is, this has turned out to be a very quiet thread. Really? No other opinions?
Is it worth it, or is it a solution in search of a problem?
Probably more useful for an OTS than a coupe or 2+2. Take the top half of an E-type monocoque away – make an OTS - and the tub will try to sag under load. Additional structural members will reduce that tendency. Jaguar created three pretty stout tubes, the two sills and the center hump/driveshaft tube, to combat that.
I think the E-type was quite rigid for it’s time, but probably pretty flexible compared to todays computer aided designs. I recall seeing an analysis of the stiffness of the coupe tub with frames attached. The structure was quite rigid with the weakest point being where the frames bolt to the tub and even there it was pretty rigid.
You mean a pair of sentences like:
BUT - ALL of that additional weight is at the floor line - meaning that it LOWERS the center of gravity, and the assembly is situated more toward the rear of the car - shifting the weight distribution to the rear. BOTH of these are going to IMPROVE handling! PLUS - you are improving the engine subframe and radius arm mounts, and while I can’t guarantee that it will save your life someday - you look at the pictures and decide if you would rather have this in there when you get broadsided…
My line is that unless you’re really going to push the car hard on a track then you’re unlikely to notice the difference between a well sorted tub and one with this mod. If you are a racer, is it worth the 28 lbs. penalty?
To me, a great many of the available upgrades seem necessary if you’ve only ever driven cars which are not well sorted. Replacing a 50 year old distributor which is completely worn out with a new 123 does transform the car - replacing a freshly rebuilt distributor which works perfectly with a new 123 gives some benefits, but it doesn’t really change the car from “barely running” to “perfect”. The original Lucas distributor isn’t a huge weakspot, unless it’s a damaged original Lucas distributor.
Andrew, I fully agree.
On top, Jaguar did not even bother to install sill stiffeners to a the low drag coupe, which has really a DHC construction:
Here goes a photo of the Lindner Nocker Low Drag E-Type 4868WK being restored:
Tadek
Stop posting those photos… If you keep at it I’ll have to find a character upgrade so that I can do jealousy of monumental proportions.
I don’t need jealousy… I’ve managed pretty well with plain old respect so far, and you’ve got mine.
About the upgrades: It’s not that I’m an absolute originality nut, or a complete cheapskate. I look at each bit as I go along and think “Ok, it was adequate back in the day. While I’m putting it to rights can I make it a bit more adequate with reasonable effort, and what will I actually gain from doing that?”
I fabricate a fair bit of stuff out of Stainless, powder coat or plate some stuff that was originally painted, and fettle everything so that there aren’t any sharp edges. I also often substitute Nylocks where a lockwasher was used, and if there is a more modern glue, paint, or insulation available I will go with that. My aim is to make the car at least as good as it was when new, and make service easier (up to, but not including, an inflatable driveshaft, but I’m thinking of using rare earth magnets to mount the IRS, fuel tanks and doors…).
For my tuppence, I would replace sills with those for the 2+2. They are longer than the stock short wheel base ones, and you don’t see them anyway.
LLoyd
Chuck for years, has been begging people to better support the areas behind sills. I think he uses a long tube support welded to the two stock supports. If I were to go that route I go for his alloy bonnet, doors/hatch as well.
Patrick
Yeah. Notice, though, that the alleged improvement in handling is attributed to the addition of weight and its corollary distribution, not the mod itself. You can achieve the same “effect” buying 28# of fishing sinkers and stashing them behind the seats.
I envy you folks who understand applied differential calculus. For the life of me I can’t figure out how to integrate the extra nine inches invisibly into the structure. (you can take the tongue out of your cheek now, Lloyd).
The question is why? Why is there a need for better support behind the sills? The rear bulkhead is a robust design incorporating eight integrated box sections tied into the longitudinal frame rails, IRS rails, sill/B-post, floors etc, much of it 18 ga and some of it 16 ga steel:
Chuck Hadley doubtless has some of the greatest experience repairing and restoring E-type monocoques as anyone. I’m sure he’s seen it all, from extensive rust damage to stress failures. As Andrew opines above, there will be no issues with a solid, well sorted monocoque but over time, many miles and exposure to the elements the structure of the monocoque may be expected to become less rigid. In that case, Chuck’s mod should be expected to maintain the structural integrity of the tub such that any time/usage/corrosion effects would be mitigated. I might also expect that the structural integrity of a reinforced tub would be less subject to compromise following minor to moderate fender benders. That is, the mod can be considered a prophylaxis.
I saw no evidence of stress failure in the tub as I cut out and replaced corrosion-compromised sections in my car, which perhaps indicates it hasn’t been subject to significant collision damage or extremely rough driving conditions. Rust is another thing entirely, but I submit one can do a great deal to prevent future corrosion issues by doing what the factory did not, and that is extensive rustproofing prep and follow through. In my case I used POR15 as a primer over sandblasted steel inside all structural surfaces followed by the application of a purpose-made wax/oil formulation.
when I did my sills, added another of the angled inner braces to the center of the sill, so I have 3 of the angled braces, instead of just 1 at either end of the sill. could make the jacking point more ridged.
but I wouldn’t jack the car up like that anyway, to scary, Roger
Hi Tadek,interestingly Martin Robey do sell what appears to be an extra piece to add stiffness to the sill structure.
Item # 16.Regards Gerry 62 Ots.
Gerry,
This is why I mentioned Robey in my initial post… 
To be honest, after looking at the Lightweight photos and considering that even Jaguar did not strengthen the sills, I think it’s pointless to strengthen them in any way in a FHC.
The sill stiffeners are not really sill stiffeners - they actually support A & B pillars.
Tadek
Sorry just re read the initial post,I would not bother either,especially on a coupe!
Regards Gerry.
During my current restoration, I realized that the “body guy” that repaired my car years ago never welded the rocker panel to the floor panel on one side, as well as many other mutilations. If i had known about Chuck when i started about 7 years ago, I probably would have added his support inside the sills. But in replacing much of the interior sheet metal I added a third support piece right above the jack point since it seem odd that the support pieces were at either end and the jack point was in the middle. I’m not sure if it adds weigh above or below the COG, or improves handling, but it made me feel better about using the jack point.
Having jacked up the body at the jack point ONCE when I first got the car I would never do it again and if the sills were apart I would put in the extra stiffeners. But my rockers did not need replacing and after talking about it with the body guy decided to not go in there.
What’s it going to hurt putting them in?
Most of the damage under my car was obviously improper jacking. Never let your car out of your sight.
Did they put a roll cage in the lightweight? That should add significant stiffness.
