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Lotus 7 Project Arrived


ianashdown

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2 hours ago, joe7 said:

Regarding sealing in the windscreen, I had to replace mine from an encounter with a rock. Had a local glass repair shop provide the windscreen (light tint green and tempered as original) and fit it in the frame, $400. They came out, helped me remove it, took it to their shop, installed the new glass and returned to help me install it. So maybe see what the glass shops recommend.

Noted that the holes in the side panel pics look very large. How were the panels attached to the frame? Are the holes in the frame that large?

And finally, when deciding on what material to use for the dash and side panels, be sure to consider what you are going to do with the seats so as to not get a mismatch.

I think, while the screen is out, I will make a wood template for possible future use.  Maybe even have a spare made if the price is reasonable and time is on my side. 

 

The holes where the screen attaches are square!  A coach bolt was used there.  I’m not sure what is correct, I’ve not checked yet.
 

I’m thinking the Marine Vinyl all round is going to be the way to go!  I like that it designed for a salt water environment, I live 2 miles from the ocean, and also for elevated UV.  I want to buy a red leather steering wheel, and will check the color match.  I can adjust the leather color if needed however.

 

Ian

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4 hours ago, MV8 said:

I for one appreciate the detailed deconstruction processes. I believe the steel in the lower windscreen channel is original. The tapered, lower corners of the glass don't have much strength and can break easily. The steel locks the lower channel into the upper to maintain alignment without relying on the glass. Is there anything inside the upper channel to ensure the top hardware does not screw into the glass?

 

Another option on the glass sealing is to use butyl rope available at home improvement stores. This is used to assemble plastic head and tail light assemblies on production cars. Treat the rope like playdough and roll it into the thickness needed to fill the gaps and extrude a bit when assembled, then rub off the excess. The problem with butyl is it will shrink and harden after a few decades. Not a problem for light assemblies that can be warmed with heat guns or better yet, placed in a 150f oven for a half hour to soften the butyl but a glass screen is not tempered and if it fit in an oven, the differential expansion of the aluminum frame may shatter the glass. Glass is cheap though; just two layers of regular residential window glass, laminated together. Just need to supply the frame or cracked original glass to the cutter. They will also chamfer (wet sand) the edges.  

 

There is a strip on the top and one on each side.  Nasty and rusty!

 

I’ve used butyl before, but not on a 7, thanks for reminding me!  It can get messy.  I believe Caterham can supply the rubber extrusion, it’ll be a while but I’m in no hurry.

 

Ian

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The rubber extrusion is between the frame and the cowl, similar to an mgb. The steel looks fine and can be cleaned with "metal prep" phosphorous from home depot and diluted with water to spray on or let it sit in the fluid, then wire brush. The threads should be chased with a tap, then the parts cleaned with acetone and aerosol painted. Rustoleum "professional" aerosol and "heavily rusted metal primer" are good paints for this.

Edited by MV8
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This is the basic section through the windscreen FYI.  So I think you can see how the steel strip would fit on top of the glass and then the sealing would be with Butyl or Mastic, but if you want to use a rubber seal it's one OR the other, but not both.

image.thumb.png.1ea131b898931ed0e527821a31c95a2f.png

Ian

Edited by ianashdown
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There seems to be some confusion.

 

A rubber extrusion goes between the bottom of the screen (engaging the lower frame in the groove shown in your picture above) and the body/cowl/top of the dash board (much like an mgb windscreen).

 

"Mastic" used to glue in modern windshields would be far too strong an adhesive and very difficult to separate and remove later. 

 

The glass is smaller than the opening in the assembled frame by the thickness of the steel inserts which provide clearance in the top frame for top snap hardware (so it won't hit the glass) and locks the ends of the lower frame into the upper frame. The lower steel attaches to the lower frame with two screws on each end but it looks like the screws were not installed based on your picture showing the threads.

 

 

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No, I understand there is a seal underneath the windscreen assembly.  My screen came removed from the body and there was no seal.  I’m just trying to reassemble the screen frame on to the glass at this point.  If the steel strips are all that positions the glass then what fills the .06”-.07” gap between the glass and the aluminum channel.  Maybe in the ‘60’s when this car was built they used the steel strip and fill the gap with a sealant.  These days Caterham use a rubber extrusion.  A much better solution in my opinion providing the size of the channel and the glass remains the same.  This video shows the extrusion I’m trying to replace.

 

Ian

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So I just fit the top steel strip and I see how the snap posts screw in to it and it does position the screen vertically, the side strips position it laterally.  But how is the glass sealed to prevent water etc?  Is the channel just filled with some kind of sealant?  What sealant might anyone have used previously?

 

Thanks,

 

Ian

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You can use bicycle inner tube, the seal the more modern cats use in the video (spacers are in the video also), or butyl. Sealing isn't critical given the gaps around the frame, doors, etc.

Edited by MV8
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1 hour ago, MV8 said:

 

You can use bicycle inner tube, the seal the more modern cats use in the video (spacers are in the video also), or butyl. Sealing isn't critical given the gaps around the frame, doors, etc.

What are you saying?  I'm going to get wet?!!

 

Good job I live in Southern California!! :driving:

 

Ian

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It sounds like you have a dial caliper. What are the dimensions of the upper channel at the spacers (width and depth of the slot)? What is the glass thickness?

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10 hours ago, ianashdown said:

What are you saying?  I'm going to get wet?!!

 

Good job I live in Southern California!! :driving:

 

Ian

I was chuckling about this, too.  I got caught in a brief shower while driving in the WVa mountains last year.  Both sides of the windshield were wet when I got back to the trailer at the hotel, but no evidence of a windshield leaks. :classic_tongue:

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1 hour ago, SENC said:

I was chuckling about this, too.  I got caught in a brief shower while driving in the WVa mountains last year.  Both sides of the windshield were wet when I got back to the trailer at the hotel, but no evidence of a windshield leaks. :classic_tongue:

I was thinking about this yesterday as I drove under heavy looking clouds, in the wrong direction, to meet some folks. I was picturing those flimsy rubber strips doing jack squat for visibility. Fortunately the clouds parted and we stayed dry.

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Nice diagram! Looks like LP-10 glass setting channel in epdm would be a good choice: https://metrommp.com/glass_setting_u_channel_lp_10/

The bottom seal looks to be the same as an mga L-shaped profile or any epdm with a 3/8 leg and what looks to be a two inch leg.

All interesting to talk about for folks who build "locosts" that are a different scale where the original screen frame and seals won't work but for you, I'd order the right bits from Cat.

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I’m still trying to settle in my mind how to go about re-sealing the windscreen in to the Aluminium channel.  I thought about the MG TC, TD even MGA etc as they use a very similar arrangement.  If you search on YouTube there are a few helpful videos.  Then, I thought I’d take a look on Moss Motors to see how they show the arrangement and what they sell for it.

 

And there it is!  Quite well illustrated and they sell a roll of flat, overly wide rubber.  I assume to trim back after the installation is complete.  I’m not sure rubber is compressive enough, but I’m going to get some anyway.  I’m also going to order some similar rolls but in a few different durometer in foam rubber, or neoprene.  I’ll test out a few options.  Water will not be a major concern for me, I just want the glass in there securely, not rattling etc, and if it’s 90% waterproof that be a victory!

 

More will follow!

 

Ian

 

PS. I should say that this method is what a couple of people had posted on here using a bicycle inner tube.  I did not really fully understand the process, but did feel that an inner tube might be a bit thin.  I have a gap of about 0.060” on each side of the glass, I think from memory, so I’m thinking a natural thickness of 0.080” or 0.090” would be a good place to start.

Edited by ianashdown
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This is my go to source for anything auto glass related , https://www.crlaurence.com/products/brands/listing/C06AB_AU

On many specialty cars, I have also used recessed rubber shims to center the glass in the channel, then run a bead of GE Black Silicone around the glass filling between the glass and channel, then let it dry and trim it flush with a razor blade, looks perfect.

Glenn

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I’m going to order up some rubber extrusions from a couple of places to see what works best.  If all else fails it think black silicone or some specific sealant will work too.

 

I’m just just getting my blast cabinet back up and running so I can blast the steel strips, then some zinc primer and a coat of black.  Not that anyone will see them . . but I’ll know :toetap05:

 

Ian

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