Advice: rebuilt DME enroute - padding for new install

[COL 911]

I have a reman exchange DME enroute for an '87 Carrera. Earlier posts have hinted at using some sort of padding under the body of the DME to reduce long term effects of vibration, etc. What is the opinion of Pelicans, pro or con?

The DME sits on the floor under the driver's seat, attached at four points. The 'footprint' or base of the DME unit is approx. 6 1/2" wide and about as long. The floor itself, is flat for 2 1/2" front to back, and then drops off approx 1". I assume the rear end of the DME 'hangs free', with a gap between the floor and the rear end of the installed DME.

I mocked up padding using some thin closed cell padding (from swimming pool liner). I'm wondering if padding under the body of the DME is worthwhile, or a general waste of time. Photos attached, thanks!

[dshepp806]

NOT a waste of time, at all! Mine's padded, too!

BEST!

Doyle

[djdsc]

I didn't pad the DME, but I did pad the relay. I used plumbing pipe insulation with the slit and self stick seam.

[BE911SC]

Originally Posted by djdsc

I didn't pad the DME, but I did pad the relay. I used plumbing pipe insulation with the slit and self stick seam.

Jung, can you post a pic of your padded relay?

[HawgRyder]

If you are worried about vibration....try using some isolators to secure the object.
The ones I am thinking of are rubber or neoprene with a stud sticking out of each end.
We used them on all sorts of mobile equipment where vibration might be a problem.
Bob

[JAR0023]

Originally Posted by HawgRyder

If you are worried about vibration....try using some isolators to secure the object.
The ones I am thinking of are rubber or neoprene with a stud sticking out of each end.
We used them on all sorts of mobile equipment where vibration might be a problem.
Bob

Along this track the studs in the floor should be long enough to insert neoprene washers between the DME and floor. -J

[HawgRyder]

If you use the neoprene washer trick...make sure the nuts are the locking style...so that you don't need to run them down tight and remove the "bounce" factor.
Bob

[COL 911]

I thought I read or was told that the DME had to maintain metal to metal contact at the mounting bolts, hence no small o-rings, neoprene washers, etc. should be used. I didn't think this sounded right, but was hedging my bets using 'plastic bedroll' solution pictured. I was concerned about any static electricity that might be generated by the plastic underlayment.

Using some sort of isolator in conjunction with the mounting bolts sounds like it would be the cleanest installation - but still can't help wondering about the effect of vibration from the rear part of the DME hanging in air over time. Maybe I'll use both! Thanks all, for the input.

[Deadeye]

Metal to metal not required, there are ground wires (brown) coming out of the ecu harness.

[James Brown]

you can always use these for mounting radios in aircraft. and put a bonding cable from the unit to the body if you want.

[Tippy]

I'm leaning on the not so good idea. The PCB's are anchored to the chassis. If you were to have uneven torque/pressure exerted (from padding being under bottomside of DME) on the 4 corners where the studs come through, it could potentially exasperate solder failures.

Dunno, just throwing it out there.

[COL 911]

The reman DME arrived, and once installed fired right up. Good to be back driving.

I ended up using surgical tubing, cut to about 1/4" length as vibration dampers under the DME at the four mounting point bolts. I added one to the DME relay mounting point as well.

I did push the "bedroll' underneath the rear of the DME where it hangs free, but it's not jammed in, just tight enough to maybe prevent some vibration in that area. The potholes here are numerous and deep!

Thanks, everybody, for the advice.

[patz]

Keep a spare DME relay in the glove. Not a URO.