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MG MGB Technical - Bonnet (hood) soundproofing
Firstly, thanks to all who have taken 30 seconds to respond to my previous questions. Much obliged!
Anyhow, another question - when I bought my BGT I was very kindly presented with the bonnet soundproofing mats to afix at my leisure. The time has come, but I am wondering what sort of adhesive to use.
Thanks in advance,
PS This weekend is the XI Tolosa classic car show. For those that don't know Tolosa is in Guipuzcoa, in the Basque country of northern Spain. If you're going, drop me a line - I am always keen to meet fellow MG owners - and we are a scarce commodity in these parts! ;)
My original 1980 soundproofing appears to be stuck on with impact adhesive, which is still holding well.
I just finished my second project and used a "spray" adhesive to attach the soundproofing. Made by 3M and called "Super 77". Comes in a black can. Not sure if you can get it in your neck-of-the-woods but might be worth a try.
So far it appears to work fine even with all the heat of a V8.
|I haven't found anything which really works that well yet. I think the trick is to really clean the bonnet well before adhering and use the strongest stuff you can find. Vapor from a hot engine will attack the glue and twice I've had my padding come loose.|
|Good old Lepages Contact cement. Installed Soundproofing mat 3 years ago using Lepages and it's still there. Wait till the glue on both surfaces is completely dry though before installing|
|I used Liquid Nails in the caulk tube, took the whole tube, been many years hasn't budged. The secret is to glue all the way to the edges of the mat.|
BTW, the mat makes a huge difference in the noise level in the cockpit. Worth every penny. Don't leave home without it.
|Next question... are you guys gluing the vinyl side or the fuzzy side?|
|I glued the fuzzy side. Is that correct? I used spray upholstry glue. As Steve says, getting the inside of the bonnet clean is important.|
|Spray the fuzzy side and the clean bonnet. Wait 10 mins and spray again. Wait another ten and fit the panels. They will fall down in time...gravity sees to that, but just re affix any slack areas.|
|Someone told me that my pad keeps coming loose because the fuzzy side is supposed to go out and the vinyl side gets glued. Normally I wouldn't believe that but he was very knowlegable on these cars.|
|Definitely not, the fuzzy side has to be stuck to the tin.|
|Fuzzy side faces towards motor to absorb heat and sound and (unfortunately) oil leaks.|
|I too am about to glue on the bonnet liner. Now Iam confused. Fuzzy side or vinyl - which? Any definitive answers as there appears to be some confusion here? Cheerz.|
|My original pads that came on the car were fuzzy side to the metal, vinyl side to the engine.|
|My car has original pads , they are fitted with an open weave hessian or jute backing towards the engine. Behind this is the fuzzy sound absorber and the noise can easily enter through the open weave (about 5mm squares.)I think the vinyl is corrct for later cars and was fitted towards the engine|
|Just removed the origila pads, Jute type - There was a soft white material between the jute and the metal. |
In mine, the fuzzy side was against the metal.
Clausager shows vinyl towards the engine (pg 15 and 115)
|Good lord, now I'm more confused than ever! Where is Paul Hanley?|
|The soft white material is probably the remains of the self adhesive backing used to stick the pads on originally. I found that the best way to replace the pads is to remove the bonnet and turn it upside dowm on a padded suface. Then take some time to remove the original pads and all the remains of any of the backing or hessian. This is a real pain, but vital. Then clean the surface with a suitable solvent or even use a scraper if needed. Be prepared to touch up the paintwork - it does not need to be perfect as it's going to be hidden anyway. Then use contact adhesive on both the bonnet surface and also on the pad having removed the backing sheet from the already applied self adhesive. Don't rely on using the self-adhesive on its own as it tends not to stick very well. The pads from the owners club come with this self adhesive - it may not be present on yours. Wait until both surfaces are tacky to touch and then install the pads. Press down firmly and carefully to remave any air pockets as you install the pads and do not be tempted to move them once installed as this will ruin the contact cement. The pads should be installed with the hessian closest to the bonnet metal and the vinyl exposed in the engine bay - looks smart and is also oil proof . Then leave the bonnet off for a futher 24hrs, preferably, to the let the adhesive go off. Replace the bonnet (another interesting experience in itself !) and hey presto !|
I did this about 3 yrs ago and seems to be very solid.
Hope this helps and good luck !
|Fuzzy side to the metal.|
|Fuzzy side to the metal when i removed the old material. I purchased the so called Space age material. Its like compressed styrofoam with a heat reflecting material (Shiny side) its also supposed to keep the heat from the bonnet and stop discoloration of the bonnet. It goes shiny side out. You can buy a sheet and cut to size. I got it on e-bay but I also saw it at Moss I believe although cost more.|
I just bought some "space age" stuff - looks like compressed thread-like material on one side and shiny foil on the other. It's about 3/8" thick. I'm presuming it's the same stuff (Moss has it) that you're talking about. The instructions said always put the shiny side facing the heat, which would indeed put it out, toward the engine, as you say. I did this on a '73 B I used to have but when the late Bob Mason saw it, he suggested that it might help the engine run cooler if you don't reflect its heat back on itself. But then, I've never had a problem with an MGB engine running too warm.
But regarding sound insulation, the previous contributions to this thread might suggest that perhaps some of the guys at the factory weren't sure either!
By the way, I've "glued" a lot of insulation with 3M undercoating. ' Just put the insulation on while the undercoating is still wet. I do NOT use undercoating as rust protection! I use it only on panels that need stiffening to reduce sound levels. The underside of the bonnet is one of them. This has worked well for me.
|Jute is for sound proofing, foiled stuff for heat.|
Replacement sound proofing I jsut installed was jute and vinyl. Jute to the underside of bonnet.
I 1st tried 3M spray adhesive. After 20 minutes of driving, I just happened to check and it had fallen onto engine.
The supplier (Northwest Imports) had suggested RTV silicone adhesive, but I didn't think that was as good as 3M. Cleaned the underside of bonnet well with wire brush and mineral spirits. Got RTV Silicone adhesive, beads all around edges to within 1/2" and multiple beads throughout remainder of area. Two people can easily align and smooth out without removing bonnet.
The RTV worked very well, have had no issues with it holding. Should have listened to Steve at Northwest from beginning :-)
|Just get a 3M adhesive that is heat resistant like that used for putting fabric on inside tops of hard tops. They have about forty-leven types of adhesive and several are heat resistant. That's what I used the 2nd time after mine came down and again when I got a new hood (bonnet) after an accident....no problems at all. Do have a friend help with alignment and install. One of those jobs that once you do it alone you always go get help for 15 minutes the next time.|
|Hi all. Just a thought on bonnet refitting..I worked at the Healey Factory in Melbourne and whenever we removed a bonnet we would first drill two 1/8 holes in the bonnet hinge on both sides before removal..This allowed pop rivets to be placed in the holes on refitting and made alighning them a lot easier.BTW.you don;t need to actually rivet the things,just place them in the holes...|
This thread was discussed between 07/06/2005 and 24/06/2005
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