Challenger Flip-top Gas Cap Differences and Question

[Floyd]

Looking at several original flip top assemblies I have and I notice two variations. One style has the metal tab screwed in place to pop the lid open. The other style has no provisions for the tab and instead uses a rubber grommet to pop the lid open. My originals have one type or the other. My assumption is that if you had the metal tab you wouldn't have the rubber grommet. I've seen pics of restored cars with both the tab and rubber grommet but don't know if those just got added during restoration.

It is my understanding that all Challengers optioned for the flip top lid also came with the locking gas cap. The locking cap does mate up well with the rubber grommet causing the flip top lid to pop open.

Anyone know if this was a design change, early vs. late thing?

ALSO... any recommendations on how to remove and replace a chrome flip top lid? I'm not sure what to call that pressed in 'rivet' or how to get it out without damage to the lid.

[MoparLeo]

It is a roll pin that attaches the top of the cap to the body mount side. Small punc and small hammer to tap it out. The "grommet" is actually the "seal" to the top of the actual cap. The flip top is really just a gas cap cover, not a cap. You have to have a cap as well as the cover or fuel will spill out after you top your tank while driving. The metal clips break that assist the coiver to open and make the clip a simple replaceable item.

[R/T's 4 R/P]

good question, Bruce.
I have an inventory of older gas cap that show the same thing.  Never noticed the small screw on spring missing on some, though.
IIRC...were the locking gas caps 70/71 only?  so, maybe the later versions removed the rubber 'seal'?
The locking style as cap is round, and the rubber seal would align with it.
The typical Cuda or B-body style gas cap would have the metal tab, and the rubber seal would not fit with it well...or at least that is what i am seeing.

If any recall the 69 Car and Driver article, they took a hard Left turn and it shows gas pouring out of the tube.  I wonder in that instance did someone think that the rubber seal was all that was needed, so there was not a true cap installed?

[Floyd]

Thanks Ron, I think you're right on locking caps for 70-71 only.  In fact, weren't flip top caps also 70-71 only?

MoparLeo - Thanks for the nomenclature on the "roll pin".  Problem with punching it out is that there is only one access hole to insert the rollpin into the lid.  It looks like it has to be pulled out.

I also didn't know what to call the rubber part.  I didn't call it a "seal" because, as you note, it doesn't really function as a seal. Agree that if there's no inner cap in place, gas is going slosh out with or without that rubber part.

[7212Mopar]

Here in CA, the fuel nozzle boot won't fit through the flip out gas cap collar. I have to fill the car manually. Not sure about the rest of the country

[318Stroker]

Here in CA, the fuel nozzle boot won't fit through the flip out gas cap collar. I have to fill the car manually. Not sure about the rest of the country

Ran into the same problem here in St. Louis when I first got my car back on the road 15 years ago. Had to hold the bellows back by hand as I pushed the nozzle in. Finally at some point they did away with the bellows, and I can re-fuel normally.

[70/6chall]

Back in 1975 during OPEC's oil embargo in the US. I had my fuel siphoned from my tank a couple of times which was to say the least pretty irritating, then had to find where the perpetrators threw my factory twist in, the flush, type gas cap. That was the time I decided to put the flip type nascar style gas cap on. Off to the Dodge dealership I went and purchased flip door cap, for $12.00 the trim ring, can't remember price and a locking gas cap to go under the flip door. They sold me a Stant G787 locking cap, which is still in place on the car. Didn't question their offer of this cap opposed to the factory locking one. I've posted pics of what they sold me and how it looks under flip door.
Thanks,   Al

[MoparLeo]

One other recommendation, put theft proof screws on the retainer ring as it only takes a few seconds with a cordless phillips screwdriver to steal your flip-top cover.

[Scooter]

Here in CA, the fuel nozzle boot won't fit through the flip out gas cap collar. I have to fill the car manually. Not sure about the rest of the country

This is the exact reason why the previous owner of mine removed the flip top. I have it on the shelf and have considered reinstalling it... but seems like a hassle to get gas in it.

[7212Mopar]

But it looks so cool.

[MoparLeo]

Too hard to put gas in your car ??? Really ??? Just takes a few minutes to fill it up.  Wear gloves...

[R/T's 4 R/P]

ANYWAYS...Getting back to Floyd's original question, who knows why there are differences in the caps?
Was it a model year application?
I have seen most with the little spring at the pivot/hinge point.

It is always more helpful to actually comment on the question posed.

[318Stroker]

One other recommendation, put theft proof screws on the retainer ring as it only takes a few seconds with a cordless phillips screwdriver to steal your flip-top cover.

Yep, had that happen to me years ago. I have tamper-proof screws on it now.

[EV2RTSE]

I'm wondering if the one on the far right is an original that came on a 1970 or 71 off the line while the other two are later over the counter parts?

My understanding is also that all flip top caps came with the locking gas caps and they were only used in 70 and 71.

Years ago (probably in the 90s) when Jack's Auto Parts was still on Route 9 in Howell NJ I bought an OEM / NOS flip top cap and trim ring (was probably still being sold by Chrysler dealers then too) from him and it didn't come with the grommet.

Note all 3 caps have the provision to be able to use the grommet and the spring clip retainer.

Just a guess but maybe as the years went by and those locking inner gas caps were discontinued and no longer readily available that's why they changed the flip tops?

I had a 1970 318 parts car that someone added a flip top cap to but it didn't have the locking inner cap, just a small twist in one. 

[Floyd]

Thanks - That's a plausible explanation.  I haven't been able to find any pics of the inside of lids from original cars yet.  I'm guessing flip tops were replaced frequently, either from theft or from the chrome giving out.