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1988-04 glass sunroof and composite top weights

9K views 39 replies 15 participants last post by  MRDANGERUS 
#1 ·
For some reason, I thought someone might need this info :scratchhead:

The 1988-04 glass sunroof weighs 18.0 lbs.
The 1988-04 composite top weighs 15.4 lbs.

As measured on my bathroom scale with tops leaning on wall:



 
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#3 ·
Interesting information but I don't think the 2.6 lb. weight difference is going to come into play when somebody decides which roof to put on.

I have both and even here in hot sunny Florida I prefer the glass roof which is heavily tinted and doesn't seem to make the cabin any hotter than when using the composite roof especially as it gives you more headroom and makes the cabin seem brighter and more spacious.
 
#12 ·
Hey, every pound counts - add lightness, yada yada! ;)

Actually, I was told the glass top was significantly heavier than the composite, so I figured why not get a number? :p

RE: glass roof DEFINITELY makes cabin hotter. On a California summer day, put your hand on the glass on the INSIDE of the car - it is HOT. The composite top is cooler to the touch.

But the headroom of the glass top is definitely worth it (about 1/2" more)

I drive with the top off when possible (like today).
 
#5 ·
Simple. The hat weighs 83.5 lbs. based on the fact that it's a 10-gallon hat with a gallon of water weighing 8.35 lbs.
 
#10 ·
Yes - it is a factory OEM tinted safety glass roof (frameless) from a V8 Esprit. It fits on my 88 but the gasket needs to change. I added foam to it to allow use with my existing composite roof gaskets (shorter height).

The glass roof is pretty rare and expensive. Just keep in mind you can buy the individual parts (I think from SJ Sports and others) for around $1400. I saw an eBay auction that went higher than that.

There is some thread discussing the plexiglass roofs - I can't remember if plexiglass was a different year OEM or aftermarket.
 
#14 ·
Glass. Not sure why yours would be plexiglass?

The first Stevens "glass" roof panels were indeed a sort of plexiglass or plastic. It was found that they would "bulge out" after exposure to the heat. So later cars were fitted with an actual glass roof.

Just searched for the changeover points, couldn't find them online or in my '88 - 92 parts book. I'm sure someone else will chime in...

EDIT Thanks Jim!
 
#17 ·
Eddie B,
Interesting. I ended up buying all the bits to make a glass roof assembly for mine earlier this year. For curiousity sake I weighed both the original composite roof the came with the car and the replacement glass (Lotus) assembly and they were within a quarter pound of each other. One variation I noticed was that the replacement glass was marked as a 'Pilkington' unit rather than the original Triplex, so I'm assuming Pilkington bought Triplex at some point or simply decided to take over the highly lucrative Esprit replacement sunroof glass market.... Right...
Anyway, I'll dig up the numbers I have, but is your weight based on the original Triplex glass, or the more recent Pilkington replacement?
Derik
 
#19 · (Edited)
Repasted here with the update - verified as XXX Lotus Glass Assembly 43R-00014

The 1988-04 glass sunroof weighs 18.0 lbs.
The 1988-04 composite top weighs 15.4 lbs.

Looks like the glass top weight is very similar, but the composite top maybe is more dense for sound deadening?

Just remembered - my glass top has added foam strips (not particularly light) - could account for some of that 0.4 lbs difference

 
#21 ·
I have had both the plexi and glass roofs. I currently have real glass. When I sold my 1st Esprit the Plexi roof was sold to another club member. I did call Saratoga to find out if they still had bits and pieces but they did not. The plexi does not require seal replacement as they have channel or double seal that fits into the gutter. Some track days do not like a real glass roof. But I have a GF roof for those instances
 
#26 ·
Update - 10/07/2015

Here is same scale, but with another composite top.
Not sure what year, but the headliner is thicker than my 88 composite top.

Total composite top weight is nearly 4 lbs heavier (15.4 vs. 19.2 lbs) and definitely heavier than my glass top (18.0 vs 19.2 lbs).

 
#27 ·
I find it amusing to hear about a couple of #'s. For most of us, if you want to make the car lighter, the best place to start is with the nut behind the wheel. The only time weight matters with the roof panels is if you are going to ship them somewhere.
David Teitelbaum
 
#29 ·
Actually, it was a follow up where someone mentioned the glass top was lighter than the composite top.

My experience was the reverse - glass was heavier than composite (for the 88). But clearly, something changed on the later cars as the later composite top is now heavier than glass - at least compared to my 88.

I bought the top for other reasons; while I was using it, I noticed it seemed heavier than my 88 top and verified that was true.
 
#28 ·
^^ Hey David, I just vacuumed out at least an OUNCE of road dust from my Esprit's carpets. :p I am MUCH happier now. Can't wait to see if I can tell on the ol' butt dyno. :D



Every little thing helps. Audi, Porsche, and Caddy (to name a few) have achieved useful weight reductions by saving ounces here and there.

For that matter, so has Lotus, with the Evora 400. :bow:
 
#32 · (Edited)
Hmmm, fair enough David. Most often it doesn't matter at all.
So, I only fill up the gas tanks about ½.
And I lost the plate holders front and rear.
And I saved some 71,118 Kg on the car so far.
And I am constantly exercising, and I weigh the same as when I was 18 y.o. (seriously many moons ago) - 75 Kg (I am 1,88 Meter).
And I use some very slim light Sparco shoes for driving ;) As I think wearing Crocs when driving is dangerous.
Do thin socks Count for something?
Maybe I should eat less before a Sunday drive, and Wear less clothes? Hm... At least I got a haircut.
Btw. I think a Lotus tshirt with print is lighter than an embroidered one?
Can I save a comma in this text?

I think it could be fun, if we start a weight saving thread (for our Esprit's). Anyone up for this?

Cheers,
Redfox.
 
#33 ·
I just thought it was interesting to see the different weights between the glass and composite roofs from different years. Nothing at all to do with a search to find the lightest bits for the car. Just a geeky little side topic of interest (for me).

Why do the roofs weigh differently? I can say that the glass roof I've weighed is not an original Triplex, but a replacement Pilkington that I put together from various sources. Maybe they saved a little $ by going slightly thinner on the Pilkington glass. Maybe we'll never know, but it's fun to theorize and discuss!
 
#34 ·
When Dick Rutan went on the around the world flight without refueling trip, every gram was precious. He and Jeanna skipped breakfast and even trimmed their nails before flight. An old hot-rodder's rule-of-thumb is every 10 pounds is equivalent to 1 HP. Colin Chapman knew that, hence "Add Lightness". It is a LOT easier and cheaper to improve performance by reducing weight rather then trying to increase HP. Aircraft from time to time go through a weight reduction program during their production cycle. Reducing the weight of the car would be an interesting exercise BUT, you can't compromise safety or reliability. Among the first things to go is the heater, A/C, radio, headliner and carpet. Anyone in?
David Teitelbaum
 
#37 ·
Hmmm - both my composite tops are outside the 'norm' defined by 04Esprit and Lorenstump.
But the glass tops are pretty close at 17.6 and 18.0 lbs.



04Esprit has:
--------------------
Pilkington/Lotus Glass Assembly : 17.6lbs
Lotus Composite Assembly : 17.8lbs

Lorenstump has:
--------------------
Lotus Composite Assembly : 17.4lbs

I have:
--------------------

Lotus Composite Assembly #2 (88+) : 19.2 lbs
Lotus Glass Assembly : 18.0 lbs
Lotus Composite Assembly #1 (88) : 15.4 lbs
 
#39 · (Edited)
Hi Dangerous,

Here's some.
The attatchment points are exactly the same as on my normal fiber roof, so everything fits straight on. Well, I forgot. Some of the fixings, which you screw into the carbon rood, are upsized 1mm, so that they last and hold better. Built in nuts etc. into the carbon roof.

I had it painted and clad in magnolia leather as my original roof (was an extra option originally), so it looks exactly like my original roof. Except when you look from inside the cabin, up on the edge between the leather and the ... leather. There you notice that it's not matte black, but matte carbon. I prefer the weight saving to be somewhat discreete. Don't want to change the looks of the car. Only the power, and the weight and the funcionality here and there. But this roof is seriously lighter, as I wrote earlier. (more on the way).
Hope this is satisfactory.

Kind regards,
Redfox.
 

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