aluminum undertray advice wanted

[lunarhighway]

Nice,,,you have a brake ???

nope, just folded everything with my hands over the edge of the workbench or along some metal bars... the folds are not perfect, but thats mostely because the edge of the bench was chipped. in the places where i needed a real tight fold i rubbed the handle of a file back and forth while applying pressure

this stuff is just great to work with, making this out of carboard would be more difficult.

the folds also make it pretty rigid... it will need some support in the center to keep it form makeing noise on the car though.

the holes where not drilled but i just punched a hole in with a big self tapping screw and a hammer and than screwed it in all the way, and than used a bigger screw to get the right size... worked faster and more presise than a drill... this method along with some hamering of the spot with a big bolt, provided a nice recess where the screws can sit.

i've been driveing for two days without any tray, and i can honestly say, the difference is big! the car feels much less stable and more noisy, can't comment on FE changes yet though, can't wait to put this on thoug!

[lunarhighway]

finisched!

[COMP]

Originally Posted by lunarhighway

nope, just folded everything with my hands over the edge of the workbench or along some metal bars... the folds are not perfect, but thats mostely because the edge of the bench was chipped. in the places where i needed a real tight fold i rubbed the handle of a file back and forth while applying pressure

this stuff is just great to work with, making this out of carboard would be more difficult.

the folds also make it pretty rigid... it will need some support in the center to keep it form makeing noise on the car though.

the holes where not drilled but i just punched a hole in with a big self tapping screw and a hammer and than screwed it in all the way, and than used a bigger screw to get the right size... worked faster and more presise than a drill... this method along with some hamering of the spot with a big bolt, provided a nice recess where the screws can sit.

i've been driveing for two days without any tray, and i can honestly say, the difference is big! the car feels much less stable and more noisy, can't comment on FE changes yet though, can't wait to put this on thoug!

well you did good

[nwbabybronco]

Originally Posted by lunarhighway

i've been driveing for two days without any tray, and i can honestly say, the difference is big! the car feels much less stable and more noisy, can't comment on FE changes yet though, can't wait to put this on thoug!

Can you please clarify the above? Are you saying no tray is worse than the political sign? Thanks!

The final result is shiny so it must be good.

[lunarhighway]

no at the time of the post i was still working of the aluminum version, and had taken of the plastic one, so for a few days i was driving with the car in stock configuration (appart form wheeldams wich i'm reviseing too)

when i originally put the first tray on i thought driveing had changed, but things like "stability" are difficult to feel when you're driveing day to day... on a windy day any car might feel less stable, but when i took the tray off again i did get the impression the car drove worse again, so i really think it did something good.

although things are not dramatic, i don't think the average person would detect if its there or not from driveing the car...

now i've been driveing for a couple of days with the aluminum version. so far it's been grate apart from a rattle when a smam the door, wich makes the car sound cheap, but a little rubber in the right place will cure that.

i get the impression the plastic version might have been a hair better at sound proofing, while the aluminum version seems to keep the heat in the engine bay longer, wich is nice.
i'd driven the car and parked it outside at my girlfieds home, quite a while later we drove of and i remember being surprised the engine was warmer and the car drove nicer right away.

i've considdered placeing the plasic tray inside the metal one to get both the sound and heat insulation, but perhaps i'll use the plastic for a rear defuser so we'll see.

i still can't comment on FE changes...haven't gone trought a full tank yet, and it'll take a few tanks to be certain it works (i drove half this tank without the tray and half with so this resuly might not show the full effect although in theory it should be slightly better than average)

as you can see the sides are still exposed. yesterday i made some plastic spacers to fair these over and to serve as a basis for better wheel dams.
i don't want to compromise brake cooling though, as i damaged a break rotor once on my last car, so i know it's possible!

i think i'll make an opening above the wheel dam so the high pressure will force air in, this will also eliminate some lift.

i hope the tray will help so i don't have to start looking for a design flaw or take it of, we'll see

[Xringer]

"i don't want to compromise brake cooling though, as i damaged a break rotor once on my last car, so i know it's possible!"


How did that happen? It would be nice to know, for us folks that are thinking about moon disc wheel covers & etc.

Thanks,
Rich

[lunarhighway]

well i'm not saying one has to do with the other, but

i had smooth wheel hubs installed from my dads retired ascona (nephew of the old chevrolet cavelier), wich look more or less like a moondisc but with vent holes at the sides, i also had an airdam extention in font of the wheels, the wheelwels had no liners in front of the tires (stock setup) so behind the bumper everything was pretty much a see trough affair...wich would not make speciffic break cooling paths needed, but might also cause hot engine air to migrate to the wheelwels.

it happened on a trip to the ardenes in my old kadett, we where going to say in a guesthouse at a farm for a weekend with some friends, it was a couple of hours driveing highway, and than some large open roads but more hills, mostely high speed driveing so i think the brakes would have been rather hot to begin with.


suddenly the GPS send me on a little road wich i though would be a shortcut to another major road but the quality of the road continued to decrease, wich got me a little agitated as i was beginning to suspect the GPS from not sending me along the best route (it turned out other people's gps from a different brand had indeed taken a better route). my girlfriend started jokeing about running a flat etc, wich didn't really help to improve my mood at the time, anyway.

suddenly there appeared a very big pothole in the road, so a slamed the breaks however with all the small rocks on the roads i skid trough it.

i feared the worsed but when i got out of the car everything seemed fine, however when we got on our way i noticed a vibration in the steering wheel everytime i used the breaks.

this vibration didn't go away, so when i got home i took of the wheel and noticed the contours of the breakpad where visible on part of the disc, i don't think the disc itself was really warped but you can tell that from just looking at it... it appeared some break pad substance was baked onto the disc.

my dad said it wouldn't be a huge problem and since i switched to another car shortly afterwards i didn't fix it, but if the discs where indeed damaged that would have been an expensive repair.

anyway.... it's one of these things that remembers you that various components on a car can get hot and that they can get damaged pretty easy under such conditions.

perhaps the mods to the car had nothing to do with it but that would only mean that these things could occur even faster when factory cooling would be decreased...

since then i try to see why engineers made a setup wich seems to be causeing drag... rather than assume everthing that sticks out into the airflow is just a design flaw... you might not be able to tell a break cooling path from all the other mess on the bottom of the car, untill you close it and the breaks overheat... wich doesn't mean things can't be improved

[Xringer]

It kinda sounds like you had some abnormal driving conditions.
All that heavy breaking during a short time frame can't be good, even for brakes that are getting good cooling air.

In any event, I'm pretty sure I'm not going encounter those conditions, but on extremely rare occasions.