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My 68 has a later dash with the speaker holes. I want add dash speakers, but the 68 dash bar cuts through the center of where the speakers need to go. I know they didnt use the bar on later cars. Is there something else that does the job on those or did they just eliminate it? Id like to get rid of mine, but dont want to compromise anything structurally.
Is the only point of that bar to support the dash? I assumed from the pretty hefty bolts on the end that it was something more structural. If so, I wouldn't feel so bad about hacking it up.
Are the dashes in later cars (i.e. '70+?) supported differently?
You need to research the construction of the '68 dash vs. '69-'75 dashes. When the speakers were moved to the dash in '69, there must have been some other support system to replace that bar. Perhaps your later-vintage dash already has the support required and that bar is no longer needed. But, you need to check that out. Whoever installed that dash could have removed some structural components (or not).
P.S. If your dash still has the speaker retaining hardware, great; that hardware is needed give the dash strength to support those speakers. If you no longer have that hardware, you will need to find some (salvaged stock parts). And, I would tell you that those dash speakers are there to provide mid-to-high frequency ranges for the sound system. DO NOT install multi-range, high-powered speakers in the dash. The 4x10" inch speakers in your kickpanels (or quality replacements for them) will provide great low/mid frequency response to go with the high-range dash speakers. The impedance of speakers that you purchase needs to match up with the output impedance of whatever sound system you put in the car. The stock Delco radio head has a 10 ohm output impedance which should have no less than 8 ohm [combined] speaker impedance connected to each side.
You need to research the construction of the '68 dash vs. '69-'75 dashes. When the speakers were moved to the dash in '69, there must have been some other support system to replace that bar. Perhaps your later-vintage dash already has the support required and that bar is no longer needed. But, you need to check that out. Whoever installed that dash could have removed some structural components (or not).
P.S. If your dash still has the speaker retaining hardware, great; that hardware is needed give the dash strength to support those speakers. If you no longer have that hardware, you will need to find some (salvaged stock parts). And, I would tell you that those dash speakers are there to provide mid-to-high frequency ranges for the sound system. DO NOT install multi-range, high-powered speakers in the dash.
The holes in the later dash I have match up to the bar, so I assume the basic structure is common among the years. I'm hoping for somebody with a 69+ car to pop up and show me what the underside of theirs looks like.
As far as the speaker plan, no worries. I'm building a complete system, so the dash speakers will be CDT Eurosport 2" wideband drivers I'll high pass at about 700 Hz getting 60 WRMS each. They'll match up to a set of 5.5" Scan-Speaks in sealed enclosures in the kicks. At the moment I'll not be running tweeters (I'm too old to hear them, anyway ). The dash speakers will be mounted to the car (not the dash) in 1L 3-D printed pods (which is a little overkill, but will let me cross them lower if I want). My original plan was to weld a bracket in place on the cross bar, then cut the section of the bar I need gone. Then I pulled it out and found out it's not steel... I can still alter it, but if there's an easier way, I'm all ears.
Hi EM,
"I'm hoping for somebody with a 69+ car to pop up and show me what the underside of theirs looks like. "
Later cars (71) have a single small bracket that bolts to the cowl and the upper pad near the center of the pad.
Regards,
Alan
The under side of the upper dash pad. Note the clips that attach to the flange on the windshield frame and the u-nuts for the screws in the lower dash pads' upper edges. This is an original dash pad.
You can take out that beam. It is NOT a structural part of any major significance. It is just to weak to provide any type of resistance IF the two hinge posts were thinking of collapsing in towards each other. To prove my point..you can easily pull down on it and watch it flex. And YES...it is to support the top dash pad made for that year model
The curved stamped steel lower windshield frame area has all that covered....because...none of this is used on Corvettes a few years later.
As I stated in my previous post, the dash speakers are ONLY intended for upper-mid/high frequencies...because they will reflect off the glass windshield and be reflected to your ears [directly]. Putting lower-mid and bass frequencies in those dash speakers will only cause rattle.
And, high frequencies don't require much power (compared to bass/mid frequencies), so planning on pumping lots of watts out of them is a total waste.
As I stated in my previous post, the dash speakers are ONLY intended for upper-mid/high frequencies...because they will reflect off the glass windshield and be reflected to your ears [directly]. Putting lower-mid and bass frequencies in those dash speakers will only cause rattle.
And, high frequencies don't require much power (compared to bass/mid frequencies), so planning on pumping lots of watts out of them is a total waste.
Have at it son, you know what you want.
No fear, the midbass will be in the kicks where it belongs. Only the high stuff (with the flexibility to adjust crossover to get the sound stage up) in the dash. And 60W in the dash isn't much compared to the rest of the drivers... I'm not that old.
Alan, your pictures are, as always, incredible. You are exactly the "somebody" I had in mind.
01-11-2018, 06:59 PM
Cross-car dash bar on 68
). The dash speakers will be mounted to the car (not the dash) in 1L 3-D printed pods (which is a little overkill, but will let me cross them lower if I want). My original plan was to weld a bracket in place on the cross bar, then cut the section of the bar I need gone. Then I pulled it out and found out it's not steel... I can still alter it, but if there's an easier way, I'm all ears. 
