Engine mounts sagging

[Bryan Cotton]

I only ordered 8! They must have been trying to get rid of them. With these bushings should I still fit the cowl so the prop is high?

[Bryan Cotton]

I found them at Jay Racing in Ohio and the best price at Moog in Texas:
http://www.moog-suspension-parts.com/spf2092bk
http://jayracing.com/mobile/index.php?m ... s_id=36051

[NWade]

Thanks, Bryan!

Question: The narrower part of the pushing (which fits inside the accessory plate holes) looks pretty short - one datasheet I found claims that this part of the bushing has a length of about 1.46mm. Does it have the depth to fill anywhere close to half of the plate's thickness (so that a pair of them fill msot of the depth of the plate)?

Appreciate the research and the work!

--Noel

[n502pd]

OK! Now I see what I was missing. The original Sonex ones have a second lip/groove that seats inside of the accy plate, and an inner diameter that is fit over the mount tube that has the bolt inside of it. The original, when tightened , are squashed quite a bit and appeared to me that the poly item need a larger diameter on the rubber ones. From Bryans phots, I can see just how the poly ones should fit.. And when squeezed tight, the poly ones should not squash anything near the way the natural rubber ones do, and hence..maybe no or at least very much less sag! I think I am now good to go and I will use my nice bright red ones!

As far as the comments on adjusting the cowl closer at the top vs bottom to account for future sag, I probably will lean towards doing that to some lesser extent than described here, just to be proactive.

Thanks also for every ones help on this! I have a much better feeling and can go forward...when I get done preparing the RV and truck and bride for the trip from Dallas area to OSH! :D :D

[Bryan Cotton]

Noel,
This Gunslinger works in inches. The lip is 1/16", for a total of 1/8" with two bushings. The hole is 1/4" deep. That makes for exactly half. That part of the bushing is so thin though I see it as more of a pilot. The big OD of the bushing should do most of the work.

Also now that I realize there is a bushing on each side, I only need to build one more Waiex instead of 3.

[Timwaiex0146]

Hi ! I just took my aerovee off the mounts after reading this thread. It has been on the mounts for about two years and has yet run . Sure enough , the holes were all oval , just from sitting there patiently. I purchased a set of the poly bushing, but they are different from the rubber mounts. They fit in the mount holes but have no shoulder like the factory rubber jobs , also when pulled tight the tube the bolts go through sits about 1/8" proud of the bushings so you need about fourfender washers to fit over the tube so you can tighten the bushings sufficiently . Does this seem right ? Any advice would be great fully appreciated. Tim 0146

[Brett]

I didn't actually end up using the poly bushes,,,,, I had them on the frame and engine mounted and it just didn't look good to me,,,,

I fitted another set from Sonex, so far so good

[Bryan Cotton]

Anybody care to guess how much sag I should allow for with the poly bushings?

[mike.smith]

Hi ! I just took my aerovee off the mounts after reading this thread. It has been on the mounts for about two years and has yet run . Sure enough , the holes were all oval , just from sitting there patiently. I purchased a set of the poly bushing, but they are different from the rubber mounts. They fit in the mount holes but have no shoulder like the factory rubber jobs , also when pulled tight the tube the bolts go through sits about 1/8" proud of the bushings so you need about fourfender washers to fit over the tube so you can tighten the bushings sufficiently . Does this seem right ? Any advice would be great fully appreciated. Tim 0146

I had someone make a mold for me, to match the Sonex bushings. Then we tried different polyurethane mixes until we got one that was harder than the Sonex bushings. No problems in 80 hours. With the Sonex bushings they had a pronounced sag after ever 50 hours or so, and eventually it was so bad I had to buy a new engine accessory plate (that big honkin' red aluminum thing the engine attaches to); the bottom holes in that aluminum accessory plate had become ovaled (not just the bushings).

My take on the problem: The upper engine mount arms are not well braced vertically so they flex a lot. The bottom engine mount arms are well braced so they don't move. This lets the engine vibrate up and down by pivoting around the base of the upper engine mount arms (the pivot point is at the rear of the arms, near the firewall). Take a look sometime and do the geometry for yourself.

There is no published torque value for the bolts. You have to REALLY tighten them so that the rubber bushings are bulging to some degree (how much is too much? I don't know). But usually the nuts bottom out at the base of the threads before that happens, so you only THINK the nuts are tight. To remedy that you need more fender washers on the nut-side, and/or shorter bolts.

[Timwaiex0146]

I'm in the middle of mounting the poly bushings , had to add four thick washers o compress the bushings without the bolts and nuts bottoming out on the bolt tubes . I would post a pic but haven't figured that out yet . I too would like to hear from anyone who has been using the poly bushings about how there working out . Tim Waiex 0146