My top lost it's memory over the summer

[DanEC]

A bit of a struggle to get it on in my 60 deg garage. Finally resorted to a heat gun to warm it a little and it snapped down OK.

BUUUT - Noticed after I had the rear bow pushed back and the windshield bows clamped down that it had pulled the top of the windshield frame up on the glass - probably close to a 1/4 inch in the middle. Is that a pretty common experience with the rest of you with tops? I don't remember seeing that last year but maybe I just didn't notice. I relaxed the clamps to let it sit awhile but that didn't relieve the pressure in the middle very much. Most of the tension is probably from the rear most bow. My main bow adjusters are screwed down to their lowest point.

[Rick Parker]

That is what the optional tension bar is for. It attaches to the top of the windshield frame and the bottom at the angled plate on the top of the cowl at the bottom center of the windshield. It prevents the frame of the windshield being separated by the stress and buffeting of the top in the wind.

[DanEC]

Originally Posted by Rick Parker

That is what the optional tension bar is for. It attaches to the top of the windshield frame and the bottom at the angled plate on the top of the cowl at the bottom center of the windshield. It prevents the frame of the windshield being separated by the stress and buffeting of the top in the wind.

I may have to resort to that. How do they attach at the top of the frame - hate to screw up my Beclawat emblem.



I moved the rear-most bow back out of position and the frame relaxed. I may need to do a bit more tweaking on it, reduce a bit of radius in the corners and shorten it a little more. I'll let it sit a few days first.

Thanks

[patrickt]

Originally Posted by DanEC

My top lost it's memory over the summer...

Hmmm, maybe your top has been hitting the sauce a little too hard?

[1795]

Dan,

It is currently 29 degrees here and with only the support on the base of the windshield, my top is not pulling up on the windshield frame at all. My top was fitted during the summer and does fit tight. I decided to store the car with the top on, just in case I get a warm spell, figuring that it would be easier than trying to install a cold top. 60 degrees really is not that cold, I had the car out for a spirited run earlier this week in 60 degree weather wearing nothing but a t-shirt and a grin. The top did not pull on the windshield at all, even at 5200 rpms.

How tight was the top fitting originally and how hot was it when you first fit the top? I have installed mine when it was cold out and it was a struggle at times, but doable and I have never seen the top pull up on the windshield frame, except once on the highway and I will leave it at that

It might be that you will need another brace...?

[mrmustang]

Put the top on, don't adjust anything, take it out and sit it in the direct sunlight for a few hours above 48 degrees. It will find it's proper shape again in an hour or two.


Bill S.

[DanEC]

Originally Posted by mrmustang

Put the top on, don't adjust anything, take it out and sit it in the direct sunlight for a few hours above 48 degrees. It will find it's proper shape again in an hour or two.


Bill S.

I pushed the rear bow up and put a couple strips of Gorrilla tape across the front of the windshield frame and down over the glass to secure the frame for now. I will probably give it a few days to relax and move it outside when we get some warmth as suggested.

The last several days have been in the 30s for daytime highs so not optimal. But my garage is well insulated and around 60 w/o heat. I fitted it last Feb and Mar and it was snug but don't remember any movement at the top of the glass that I noticed. Since I was sweating over every detail I think I would have. It was definately the rear bow pulling it out of position since as soon as I pushed it up to the top the frame top moved back down in position. I also probably need to secure the side clamps before moving the rear bow in position as it transfers tension down the windshield uprights which should relieve some of it off of the header.

Thanks for the input.

[strictlypersonl]

Actually, fiberglass has a negative coefficient of thermal expansion, so the body grows as it gets colder.

Anybody want to buy a bridge?

(Sometimes, I just can't help myself...)

[patrickt]

Originally Posted by strictlypersonl

Actually, fiberglass has a negative coefficient of thermal expansion, so the body grows as it gets colder.

Just like ice... just tell him it's a hydrogen bonding thing.

[DanEC]

After studying my bows I went ahead and trimmed another 1/4 inch off of the rear-most bow as it was actually keeping the main bow from joining together completely. Still very tight but it's all in place with a couple strips of tape holding the frame at the center. Weather isn't cooperating but we may get a 50 degree day next weekend - but not promising any sunshine. Hopefully it will relax over a couple weeks in the garage and I can peel the tape off.

I'll tell it to lay off the sauce Patrick. Bob - that's an interesting fact about fiberglass I had not heard of before.

[strictlypersonl]

Originally Posted by DanEC

... Bob - that's an interesting fact about fiberglass I had not heard of before.

"Believe nothing of what you hear and only half of what you see."
Benjamin Franklin

[DanEC]

Originally Posted by strictlypersonl

"Believe nothing of what you hear and only half of what you see."
Benjamin Franklin

Ahh - a mischievous post. Got it.

The thermal expansion behavior of three epoxy-fiberglass composite specimens was measured from 20 to 120°C (70 to 250°F) using a fused quartz push-rod dilatometer. Billets produced by vacuum-impregnating layers of two types of fiberglass cloth with an epoxy were core-drilled to produce cylindrical specimens. These were used to study expansion perpendicular and parallel to the fiberglass layers. This type of composite is used to separate the copper conductors that form a helical field coil in the Advanced Toroidal Facility, a plasma physics experiment operated by the Fusion Energy Division at Oak Ridge National Laboratory. The coil is operated in a pulsed mode and expansion data were needed to assess cracking and joint stresses due to expansion of the copper-composite system. The dilatometer is held at a preselected temperature until steady state is indicated by stable length and temperature data. Before testing the composite specimens, a reliability check of the dilatometer was performed using a copper secondary standard. This indicated thermal expansion coefficient ( α) values within ±2% of expected values from 20 to 200°C. The percentage expansion of the composite specimen perpendicular to the fiberglass layers exceeded 0.8% at 120°C, whereas that parallel to the fiberglass layers was about 0.16%. The expansion in the perpendicular direction was linear to about 70°C, with an α value of over 55×10-6 °C-1. Anomalous expansion behavior was noted above 70°C. The expansion in the direction parallel to the fiberglass layers corresponds to an α value of about 15×10-6 °C-1. The lower α values in the parallel direction are consistent with the restraining action of the fiberglass layers. The α values decreased with the specimen density and this is consistent with literature data on composite contraction from 20 to -195°C.
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[1795]

Originally Posted by strictlypersonl

"Believe nothing of what you hear and only half of what you see."
Benjamin Franklin

I think that goes without saying given the bevy of characters that reside here

[DanEC]

Originally Posted by 1795

I think that goes without saying given the bevy of characters that reside here

Yeah - but this time I think I got caught holding the bag on the annual snipe hunt.