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-   -   aluminum undertray advice wanted (

lunarhighway 05-19-2008 07:29 AM

aluminum undertray advice wanted
i'm toying around with the idea of an aluminum undertray, that will attach to the subframe and slope slightly down from the front bumper as does the subframe, so it will shield the engine carter, transmission and exhaust from the airflow.

the undertray will have to be easily removable from underneath the car.

right now the attachment method i envision are U frames that hug the sides of the subframe and that are rivetted to an aluminum sheet, however this would make it difficult to remove.

so i'm looking for some inspiration from real world examples.

what i want is something that won't fall off out of itself but can be easilly removed without leaving to much traces when needed.

can i just hang something from a subframe or would this disturb the cars handling etc?

for now i'll work on a simple temporary solution to see what the effects are

Daox 05-19-2008 07:43 AM

I'll be putting mine on with tapped holes and bolts. However, I fastened my coroplast tray that is under my engine bay with sheet metal screws into the plastic bumper cover, and I used plastic expanding fasteners into the existing subframe at the rear.

blackjackel 05-19-2008 08:48 AM

how about using that stuff that tears apart easy, i dont know what its called but its got hooks and a fluffy part that it clings to... just uuse a whole crapload of that stuff...

lunarhighway 05-19-2008 09:31 AM

you mean velcro? usefull stuff but i doubt it will hold an aluminum plate on maybe if i cut slots in it and use it to tie loops around the subframe... still it doesn't strike me as something that looks very solid...


I used plastic expanding fasteners into the existing subframe at the rear
did you drill holes in the subframe or did you use existing ones? i'd rather not make any structural alterations to such a load bearing structure... well i can't really as tech inspection would not allow it.

edbso 05-19-2008 01:55 PM I went a different route. I used Lexan for durability here in the front I used the bolts and plate for the tow hook to secure it and sheet metal screws into the existing plastic undertray.

nwbabybronco 05-21-2008 03:37 AM

I'm curious whether a commercially available rally skid plate might fit this description.;800x600].jpg

jim-frank 05-21-2008 08:40 PM

If you can't drill the subframe, how about using epoxy to attach flat head bolts to the frame, then use (nylon insert) locknuts to hold the belly pan up? That will not impair the strength of the subframe, and if done neatly, will not raise any eyebrows at a safety inspection.

}{ead$hot Zod 05-21-2008 09:50 PM

I've started taking some welding classes to tackle problems like this. I have a little more room under my truck to make the belly pan rounded though. You may try making a small frame (7/8" Unistrut) that bolts to the cars frame and then attaching the metal to it. Maybe with dzus fasteners.

nwbabybronco 05-23-2008 11:57 PM

I emailed the rally skid plate manufacturer. He indicated that some people have claimed a 1-2mpg improvement, but didn't seem to want to promise anything. He and a colleague did indicate that some additional vibration or noise might be noticed.

adrive7 05-24-2008 12:11 AM


Originally Posted by }{ead$hot Zod (Post 27590)
Maybe with dzus fasteners.

For easy on and off of a body panel, its hard to beat Dzus fasteners. A flat head screwdriver is all you need to remove the panel is about 30 seconds. Faster if you can move quickly. The downside is you will need to weld on your frame.

You can also get them with tabs you can turn without a screwdriver.

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