Mirrors, revisited
- Thread starter wrath
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Yeah, for the number of hours spent, I think I'd rather cast one out of aluminum.
Cool!! So, now that you have a printed mount, how about doing 4 of them. Take them to a foundry and have them use the prints as a mold and pour them in aluminum. A little light machining and some paint gives you something to sell to us that are interested.
There is a fella that owns a GMC, and is a member of the Greater Midwest Classics. He used to teach pattern making and foundry in his working days. Might be worth talking to him if interested in taking this further.
Gaskets finally showed up yesterday. They're made from 1/4" crappy foam. Like cheap yoga mat or drawer liner forum. Even worse than what come with Grote lights. I could be wrong but I doubt they're UV stable and they appear to be permeable. To the dumpster they go.
The black molding for the body showed up also. I had grand ideas of them being beautifully cut and ready to go for the price. Instead it looks like someone gave a blindfolded Michael J Fox a pair of garden shears and told him to use his imagination. I was at least hoping something that I couldn't do better with a dull box cutter.
I'm actually afraid to open the rest. I can only survive so much disappointment per time period.
The black molding for the body showed up also. I had grand ideas of them being beautifully cut and ready to go for the price. Instead it looks like someone gave a blindfolded Michael J Fox a pair of garden shears and told him to use his imagination. I was at least hoping something that I couldn't do better with a dull box cutter.
I'm actually afraid to open the rest. I can only survive so much disappointment per time period.
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Wow, imagine if every car came with side view displays instead of mirrors. A lot of gas would be saved.
I've been driving it around a lot lately trying to work out the kinks (mostly related to the fool-injection). One thing that is driving me crazy is the buffeting caused by these new mirrors. I've been trying to adjust the housings up/down/side-to-side trying to get rid of it. It's so deafening that I might as well have skipped the $1500 worth of dynamat and run it with the doghouse off.
The buffeting starts at about 63mph and is still there at 95mph. Past that the engine air intake is too loud for it to matter. I would like it to not exist at least until 77mph. It cruises nice at 77mph.
Anyone else figure out what causes it? I know it must be the mirror shape and its relation to the windshield.
The buffeting starts at about 63mph and is still there at 95mph. Past that the engine air intake is too loud for it to matter. I would like it to not exist at least until 77mph. It cruises nice at 77mph.
Anyone else figure out what causes it? I know it must be the mirror shape and its relation to the windshield.
Well i guess if you want to test your theory of the shape verse the windshield, if possible, turn the mirrors sideways [facing the coach] and see what that does. If the noise reduces that is the issue, if it remains it will be the support arms [i'm assuming the noise did not exist before the new mirrors were added]
I know it has to be the shape. Old mirrors didn't do it at all.
I took it on the expressway for the first time since the new mirrors and set the cruise for 80 and messed with the mirrors while driving (safety second).
If you hold your hand near the top inside of the mirror the noise goes away. I was thinking about making some airfoils to solve the problem... but I can't believe no one else has this problem.
Before you could sit there with the windows open, the roof vents open, and cruise at 75 and have a normal conversation. Now your eyes feel like they're going to pop out of your head.
It's not a problem with the windows closed.
I took it on the expressway for the first time since the new mirrors and set the cruise for 80 and messed with the mirrors while driving (safety second).
If you hold your hand near the top inside of the mirror the noise goes away. I was thinking about making some airfoils to solve the problem... but I can't believe no one else has this problem.
Before you could sit there with the windows open, the roof vents open, and cruise at 75 and have a normal conversation. Now your eyes feel like they're going to pop out of your head.
It's not a problem with the windows closed.
It sounds like you've created a giant flute from hell. Perhaps you can change the spacing between the mirror and coach for testing? It's probably perfectly wrong right now, and moving in either direction may disrupt the phenomenon.
I trolled Mr Google and the only complaints i saw was the Prevost guys [vibration].
The interesting thing here and the reason i asked about speed, is their are a ton of these mirrors used on GMC's with the average driving speeds in the 65 to 70mph range with no compalints......... so something is different between what you have and what they have for mirrors.
Do me a favor and post up a head on shot of the front of your GMC.....get far enough back that you can clearly see the front and the 2 mirrors....lets see if we can spot anything.
The interesting thing here and the reason i asked about speed, is their are a ton of these mirrors used on GMC's with the average driving speeds in the 65 to 70mph range with no compalints......... so something is different between what you have and what they have for mirrors.
Do me a favor and post up a head on shot of the front of your GMC.....get far enough back that you can clearly see the front and the 2 mirrors....lets see if we can spot anything.
Well...
There are no holes or gaps in the wheel well liners. I even plugged the holes for the seat base bolts.
There are no holes in the fenders for air.
The gap between the bumper and the body is filled with a PVC pipe used for vacuum reservoir.
The driver front cavity in front of the tire is where the engine air intake and filter box is located. There is shielding to try to keep hot air from going back between the wheel liner and radiator to go in the intake.
There is shielding on the passenger side of the motor also to protect the Fitech FCC.
There is a lot of dynamat and polyurethane sealer trying to direct airflow and reduce noise.
I have modified the radiator air intake significantly over factory. If it comes through the grill it has to either go through the radiator or through the dash vents. Everything else has been plugged with sheetmetal and EPDM rubber way better than the lousy factory setup.
If it goes under the bumper there are air guides there also as an attempt to keep the engine fan from sucking the same air through the radiator over and over when parked. It's a PITA to keep a Cadillac cool with a clutched fan.
At 40+mph there is little to no air that comes out of the wheelwells (testing in rain). Originally air came out of the wheelwells such that you were riding next to mist from the Big Sur while driving in the rain. There is a compression wave or whatever you want to call it about 2' in front of the front tires. It practically blasts the water off the ground. It reminds me of pulling my travel trailer (parachute) with my truck as far as air currents on the ground.
So yeah, lots of air changes from factory. However, other than switching to electric wipers nothing above the beltline is different other than the mirrors.
The cabin is quiet enough with the windows closed all you can hear is the gentle whine of the transmission at 65.
I was experimenting and if I open the window in front of the door about an inch the buffeting largely goes away.
I think the best part of these vehicles is being able to drive around with the windows open but to be honest I've never seen anyone drive around with their windows open.
There are no holes or gaps in the wheel well liners. I even plugged the holes for the seat base bolts.
There are no holes in the fenders for air.
The gap between the bumper and the body is filled with a PVC pipe used for vacuum reservoir.
The driver front cavity in front of the tire is where the engine air intake and filter box is located. There is shielding to try to keep hot air from going back between the wheel liner and radiator to go in the intake.
There is shielding on the passenger side of the motor also to protect the Fitech FCC.
There is a lot of dynamat and polyurethane sealer trying to direct airflow and reduce noise.
I have modified the radiator air intake significantly over factory. If it comes through the grill it has to either go through the radiator or through the dash vents. Everything else has been plugged with sheetmetal and EPDM rubber way better than the lousy factory setup.
If it goes under the bumper there are air guides there also as an attempt to keep the engine fan from sucking the same air through the radiator over and over when parked. It's a PITA to keep a Cadillac cool with a clutched fan.
At 40+mph there is little to no air that comes out of the wheelwells (testing in rain). Originally air came out of the wheelwells such that you were riding next to mist from the Big Sur while driving in the rain. There is a compression wave or whatever you want to call it about 2' in front of the front tires. It practically blasts the water off the ground. It reminds me of pulling my travel trailer (parachute) with my truck as far as air currents on the ground.
So yeah, lots of air changes from factory. However, other than switching to electric wipers nothing above the beltline is different other than the mirrors.
The cabin is quiet enough with the windows closed all you can hear is the gentle whine of the transmission at 65.
I was experimenting and if I open the window in front of the door about an inch the buffeting largely goes away.
I think the best part of these vehicles is being able to drive around with the windows open but to be honest I've never seen anyone drive around with their windows open.
Here's what i would do as a mechanic if you brought that to me to try to fix......first thing is i would measure the gap between the mirror body and the windshield....compare to stock.....if not the same i would make it the same, so loosen the top mirror mount - put in a wedge, snug up and tap closed with duct tape to road test....if noise gets worse wedge the mirror closer and see......
You may have to fine tune the mirror base position to get this right.....i know you shouldn't have to do this but....
If you dont want to mess about contact your supplier and see what they say?
You may have to fine tune the mirror base position to get this right.....i know you shouldn't have to do this but....
If you dont want to mess about contact your supplier and see what they say?
The shape of the mirror between a Ramco and a pancake farmtruck mirror from the 70s... not even close. The Ramco is significantly larger and four times the depth. It is marginally closer to the body, but mostly because it is wider. The Ramco arm is also comparatively large with regard to the fact that the factory arm is a piece of 3/4" round bar stuck to a piece of stamped steel.
I suspect the "aerodynamic" nature of the mirror is causing the problem. If it were ugly and flat I bet there is enough air disturbance to cause a wash that it doesn't happen.
The part that has my attention is that no one else has had this problem. If I spent $480 for a set of mirrors I'm going to hassle with then why didn't I just build some arms out of stainless and slap on a cheap pair of Velvac fleabay mirrors for $50? I was trying to buy myself out of a time vampire.
I'm wondering if all the time I've spent trying to seal up the interior and the modifications related to the front has caused me all of this grief. If I open a window inside (preferably the one in front of the door) the problem goes away.
I suspect the "aerodynamic" nature of the mirror is causing the problem. If it were ugly and flat I bet there is enough air disturbance to cause a wash that it doesn't happen.
The part that has my attention is that no one else has had this problem. If I spent $480 for a set of mirrors I'm going to hassle with then why didn't I just build some arms out of stainless and slap on a cheap pair of Velvac fleabay mirrors for $50? I was trying to buy myself out of a time vampire.
I'm wondering if all the time I've spent trying to seal up the interior and the modifications related to the front has caused me all of this grief. If I open a window inside (preferably the one in front of the door) the problem goes away.
