ZephTheChef

So after adding vibration damping mats and mass loaded vinyl under my hood for soundproofing, the stock shocks no longer hold it up. I had been propping the hood in the meantime, but finally found a site that allows you to search for lift supports by dimensions. The stock lifts are listed as 61 lb force, so I did a search and came up with several replacement candidates dimension-wise varying between 40 and all the way up to around 200 lbs.

I really don't know what strength to get. If I go too light, I will end up with the same problem, and if I go too heavy the hood will be difficult to close and it could potentially bend or damage something. Any input on this, or has anyone dealt with this before?

I went ahead and ordered some 80-lb replacements and will report on how they do. There's also the chance my stock lift supports are slightly worn out and that new stock ones might hold the hood. I added quite a bit of weight...that MLV was 1lb/square foot. Anyway, I thought it might be helpful for other people in the future if I posted the link to the ones I am getting/the site where you can search to match your application.

http://www.liftsupportsdepot.com/lif...trut60077-10w/

doni01

iTrader: (1)

What's wrong getting OEM's ??

ZephTheChef

They aren't strong enough to hold my hood up with all the extra soundproofing I have added.

shooffnyc

Are you sure your original hood strut you have is still holding to its designated pressure?

ZephTheChef

It is very possible a brand new stock set might cure my problem. But the hood stayed up just fine before the soundproofing and it *almost* holds itself up now. I have had both shocks removed to test them individually and they are pretty stiff (were a huge pain to get back on), so I know I don't have one completely blown or anything. So I thought it would be a good idea to get some at least slightly uprated ones. If they are too strong then I may run one stock and one of the new ones.

ZephTheChef

Update:


The supports arrived today. 80 lb ones turned out to be a bit stiffer than I would have liked. Installation was a real pain (took two of us). When I got the first one swapped, the hood would hold itself but had no lift to it. With both installed, it now slowly lifts itself once I get it about 1/4 of the way up manually. They aren't excessive to an unacceptable degree (it's not difficult to close the hood or anything but it does require deliberate force). They are definitely not a perfect match. I probably should have gone with the 70 lb struts. I'm going to inquire about exchanging them, but if that doesn't work out then I'll just live with it. It's not a big enough deal to shell out another $60 for...it's certainly still better than the hood not holding itself open.

shooffnyc

That sux. But yeah better than non working struts. When ur the first to try it, it's always trial & error.

Others learn about mistakes at your expense. Trust me, others will thank you one day when they are looking for the right hood strut and stumble at your thread.

ZephTheChef

That's exactly why I posted the update. If it saves even one person some money or frustration then that's great.

To add a little information about how much weight I had added to the hood to cause this issue in the first place, it was .25" thick mass loaded vinyl cut to match the factory underhood padding, and about a sheet and a half of Noico 80-mil vibration dampening mat. I had figured probably 20 lbs total give or take, but I really should have weighed the MLV sheet before attaching it. The stock shocks are listed either as 61lb or 65lb, so I figured I didn't want to come up short and 20/2=10+65=75 so I rounded up to 80 since a 75lb shock wasn't listed.

I have decided to not mess with an exchange. The hood closes just fine from the front. It's just a bit of a bear if you're trying to close it one-handed standing off to one side. I'd rather them be just a little stiff than right on the edge and have it fall on my head while I'm working under the hood after they wear in a little, lol.

AMG 17GT

Why are you soundproofing a quiet motor?

ZephTheChef

The story of why I soundproofed underhood is actually more directly related to the fact that I had purchased a bunch of soundproofing stuff to cut down on what I feel is a ridiculous amount of vibration and road noise for such a high end car, and underhood just happened to be the easiest place to start (without really having to disassemble anything). And yes, my motor mounts are recent replacements in good shape and I already replaced the ABC dampener...as well as fixing a few lines that weren't properly isolated so I do know what it feels like when something is actually wrong, I am just particularly sensitive to even what most would consider a normal level of noise/vibration in this car.

On that note, I would hardly call it a quiet engine anyway, they are fairly noisy...even just normal things like the injectors and EVAP solenoid clicking away, let alone the system as a whole. Maybe it's silly of me, but I feel like it's worth it.

ItalianJoe1

Very interesting. I can't imagine that much noise coming through the hood and reaching the interior. For me the car is almost too quiet stock, feels like an electric car compared to most engines.

Curious to see what makes the biggest difference.

ZephTheChef

It's acceptable stock. But not super quiet. I wasn't even originally planning on doing the hood but I thought it would be good practice and knew it would be a while before I find a good time to mess with the interior so it was hood first, fenders next (because I ended up having all that pulled apart doing the intercooler upgrades), probably the trunk next because it's relatively easy and then I'm sure it will be one door at a time. No idea if I'll actually ever get around to gutting the interior and doing everything.

The biggest thing for me is it just feels like it has quite a bit of road noise. Much more so than my 1998 Buick Park Avenue (which really has a TON of padding under the carpet and such). I'm really excited to get it back on the road after I get the wheel arches and trunk done to see how much of the noise that cuts down. I couldn't believe it when I was drilling the holes for the intercooler lines to the trunk that the whole trunk floor is just some sort of fiberplastic. No sheet metal whatsoever. I'm sure that's part of why I can hear the exhaust resonance so much on decel after ditching the cats. I am definitely looking forward to getting that area better insulated.

tusabes

Im confused - when you want it quiet leave the exhaust cutouts closed and when you want it loud route the exhaust through the open cutouts ! If your cats are deleted even when the cutouts are closed , put them back in. Only use the cutouts when you want the sound

A biturbo 600 is one of the quietest cars when left in stock form. I couldn't even hear the exhaust note on a biturbo cl600 when I floored it

ZephTheChef

I want my damn cake, but I want to eat it, too.

I wouldn't really say it's louder with no cats...there's just a particular RPM at low load (particularly on decel) where the exhaust resonates now and makes sort of a higher pitched drone. It may well have been present with the cats in place, I just didn't notice it because I usually have the radio on. I had it off on purpose after installing the cutouts because I wanted to listen to the exhaust, lol. So then I noticed the slight drone as well.

The Y pipes for the cutouts replaced the cats. There's no putting them back. So with cutouts closed it is the complete stock system, just minus the cats. And it's quiet...just has a certain resonant frequency. I suspect the little odd triangle merge pipe is a significant contributor to the noise because I can hear and feel that section vibrating when I'm under the car with it idling on the lift (I spend a lot of time under this car, lol). I don't know what that pipe looks like inside but for some reason it makes noise. I actually have a couple hockey pucks strapped to it to cut down on the vibration. Which sounds kind of like a ridiculous idea, but it's pretty darn effective. I'm surprised these cars don't have factory exhaust dampers...a lot of BMWs do.

But the soundproofing didn't really have anything to do with the exhaust drone either. It really was mostly about the road noise. Which I know probably has more to do with the sport tires than anything else, but we all know I can't change those cuz racekar. So obviously the only rational decision is to add a ****load of weight to make it slower.

cybertronicify

When changing the lift supports, it helps to open the hood completely vertical. This allows you to slip it on without compressing the shock too much by hand.

ZephTheChef

Oh believe me, I had it all the way against the stop...it was still probably 3" of compression needed. Not a big deal with the factory shocks but these bigger ones were a huge pain. I was afraid I was going to bend or break the mounting bracket.

wallyp

Zeph,

Forgive me if you already know this, but...

If you lift the hood as far as it will go;
then press the small tab on the side of the left hinge and lift the hood just a bit more;
then continue to hold the hood up as far as it will go and walk your way around to the right side;
then very slightly release the upward pressure without actually allowing the hood to drop any appreciable amount;
then press the release tab on the right hinge;
you can then raise the hood to the completely vertical position, where it will latch into place.

To lower, push the hood up a little, press the left release, then lower the hood. Some cars may require both releases to be pressed.

ZephTheChef

I was not aware. I hadn't spent much time examining the mechanism. Thank you, that will surely come in handy in the future.

ZephTheChef

Small update on this, I have drastically improved the drone, and can now confirm it wasn't caused by deleting the cats. I had a very small exhaust leak right where I had welded the tips back on after installing the flappers/dampeners. It was a round to slightly oval joint, and I had welded it with the exhaust system in place, just dropped down a little bit (still not very good access or visibility) so it was leaking a bit. I didn't think it would matter since it was post-muffler and physically inside the slip-on tip itself, but obviously it did. It must have been reflecting some of the sound back under or towards the front of the car since the exhaust was able to exit to within the outer shell of the tips. I used a tube of the versachem exhaust joint sealer around all those welds and it's now quieter than it's ever been. I don't know if I would trust the stuff on pre-muffler exhaust, but it really doesn't get very hot right at the tips. It's supposed to be good to 1000 degrees. I also added another hockey puck damper on each side around the muffler hangers to further reduce/absorb resonance and vibrations.

Probably should be posting this information in my cutouts thread as opposed to a completely unrelated thread on hood lift struts...but since this thread is where it was brought up, this is where the update is going, lol.