69 F41 spings and compressed upper A-arm bumpers

[Mark S.]

In process of chassis reassembly with my frame off the ground on a jig. Recently installed new original upper A-arm bumper rubber in the spring towers before installing the F41 coils and bolting the spindles back on. Lots of spring pressure pushed the lower arms down and pulled the upper arms down onto the bumpers. I was installing the shocks yesterday and noticed that all that tension crumbled the upper A arm bumpers. I will now have to go back and unbolt the upper ball joint from the spindle to raise the upper A arm and install new bumpers. Not exactly a fun project....

After I reinstall the bumpers how can I keep this from reoccurring since the frame is off the ground and there is no weight to counter the spring tension?? Once the car is back on the ground with the 427 installed that will compress the spring and center the suspension at the normal ride height. Has anyone had this happen while reassembling? Any suggestions so that i can put new bumpers in and avoid the same issue while the car is on the jig?

Thanks,

Mark

[Richard R.]

Re: 69 F41 spings and compressed upper A-arm bumpers

Mark,

I have a 69 L46 with regular suspension. How I handled this issue was I left a piece of rubber sheet where the bumper goes then installed the bumper after I had the engine and body on the frame. There is a post somewhere that describes how this is done. You don't have to remove the upper ball joint to accomplish this. At least I didn't have to. But I don't have experience with the F41 suspension though.

Rich

[Mark S.]

Re: 69 F41 spings and compressed upper A-arm bumpers

Thanks Rich. Appreciate the reply. will probably put something in between a arm and spring tower to prevent them from touching.

[Richard M.]

Re: 69 F41 spings and compressed upper A-arm bumpers

Mark, I just noticed your posts and need to ask.....

Are the new crumbled bumpers reproduction parts? Vendor? Manufacturer country?

When St Louis built these, even with F41, I suspect they never had that issue. Rubber was better then. These days I prefer to use old US rubber as opposed to brand new rubber from anywhere, especially the Far East.

There have been many reports of other reproduction rubber parts disintegrating in a short time. Like rear spring outer cushions, etc.


Rubber Rant....

If you bought a bag of made in china rubber bands a few years ago, check them. They will be a gooey, brittle mess right in the bag. This is what's going on now.

Chinese Trailer Tries? a.k.a."China Bombs" on the camper forums. Reports of sidewall blowouts within 500 miles of use.

Our new camper came with "Castle Rock" trailer tires. I took those 5 brand new China tires off and threw them out. Got 5 new USA Goodyear Endurance tires. Made in North Carolina & Alabama. The Goodyears are about $8 more per tire than the Castle Rock via Tire Rack.

When we removed the CRs from the 5 wheels, the sidewall was like packing foam soft. The GYs were extremely firm and thicker. The Load range value on the GYs are about 150 lbs higher than the CRs iirc.

There have also been reports of the new spare tires less than a year old rom CR actually splitting from non use with a year of ownership. Sidewalls split or blowouts right under the cover. One camper got a blowout on the road and went to use the spare and found his unused new spare was also a China Bomb.

I just replaced the USA Michelins X-Ones we had on one of our cars. Still like new and pliable, DOT dated late 90's. I would have trusted those more than brand new offshore tires.

Rubber Rant Over.

Rich

[Mark S.]

Re: 69 F41 spings and compressed upper A-arm bumpers

I'm with you on the china thing. try real hard not to buy anything from there...

Those were original GM rubber new in the boxes. Probably 30 plus years old....

[Gary B.]

Re: 69 F41 spings and compressed upper A-arm bumpers

Thanks Rich. Appreciate the reply. will probably put something in between a arm and spring tower to prevent them from touching.

Mark,

What I did is buy a 12” x12” x 0.5” thick sheet of rubber on Amazon for $15.11. The hardness spec fir the rubber is 70 Shore A, which feels somewhat similar to the upper A-arm rubber bumpers. I cut eight, 3”x3” squares from the rubber, to make a stack of four squares for each upper A-arm. For the four per side, I used a hole saw to cut 1.5” diameter holes in two of the squares, a 1” hole in the 3rd square, and I left the fourth square with no hole. I then used Tom Nowak’s 5/8” diameter rod system to compress the spring to lift the upper A-arm off the bumper enough to place the four squares, one by one, over the GM bumper, with the squares with the 1.5” holes placed first, then the square with the 1.0” hole, then the no hole square on top. Then I removed the spring compression screw to let the upper A-arm come down on top of the four stacked rubber squares surrounding the bumper. The four squares compressed about 1/2” to 3/4”, so there is still some compression in the GM bumper, but nowhere near as much as before I added the temporary rubber squares. I did thus after I had left the bare chassis with suspension sitting for 6 months with the upper rubber bumper squashed to about 25% of its normal height. Fortunately when I went thru the process of adding the protective rubber squares, the rubber GM bumper looked completely normal. I had been prepared to see it stay totally flat or cracked, so I breathed a huge sigh of relief when it looked normal.

Gary

[Mark S.]

Re: 69 F41 spings and compressed upper A-arm bumpers

Thanks Gary. That's a great way to handle that...Certainly seems like the cleanest way to protect the bumpers. I will try this...

Mark

[Gary B.]

Re: 69 F41 spings and compressed upper A-arm bumpers

Mark,

Instead of what I bought, this is what I would recommend getting to make the pads:

https://www.amazon.com/Styrene-Butad...4379732&sr=8-1