1967 Lower Control Arm Rubber Bumper Mount Hardware

[Steven B.]

Re: 1967 Lower Control Arm Rubber Bumper Mount Hardware

The other side is correct, because I had to replace the linkage as it had come loose one day as I was driving down the road. Didn't get around to the other side.

Steve

[Tom D.]

Re: 1967 Lower Control Arm Rubber Bumper Mount Hardware

The chassis was "up side down" when this was installed?

[Bill M.]

Re: 1967 Lower Control Arm Rubber Bumper Mount Hardware

Design intent was probably with the nuts on the bottom. The rubber bumper is designed to be fully compressed before you get to metal-to-metal, which is where something metal will bend. You don't want the bolt shank to contact the frame before the bumper is fully compressed.

The guy on the line may have found it easier to install the bumper with the nuts on top.
(Assuming the bumper was installed on the chassis line and did not come in PIA (part-in-assembly).)

[Stephen L.]

Re: 1967 Lower Control Arm Rubber Bumper Mount Hardware

Tom Dingman, The chassis looks upside down to me, in these photos...... probably easier to install suspension components in this position......and then flip over and send to the next assy line.

[Stephen L.]

Re: 1967 Lower Control Arm Rubber Bumper Mount Hardware

Bill Mashinter, It is my understanding that parts that are called out with part#s etc. in the AIM were installed at St Louis on the assembly line.

The bumper being discussed in this thread is NOT the rubber bushing holding the sway bar to the frame which is compressed under the metal loop, but rather, the rubber bumper attached to the lower control arm which is commonly known as a "rebound" bumper.....

[Bill M.]

Re: 1967 Lower Control Arm Rubber Bumper Mount Hardware

Bill Mashinter, It is my understanding that parts that are called out with part#s etc. in the AIM were installed at St Louis on the assembly line.

The bumper being discussed in this thread is NOT the rubber bushing holding the sway bar to the frame which is compressed under the metal loop, but rather, the rubber bumper attached to the lower control arm which is commonly known as a "rebound" bumper.....

It is a jounce bumper.

[Richard M.]

Re: 1967 Lower Control Arm Rubber Bumper Mount Hardware

Thank you Gents....

Yes I think Leif mentioned the sway bar rubber but it's the jounce/rebound rubber in question. Interesting discussion about the other rubber too so it's all relative.

Yes the frames were upside down during assembly so based on fabrication preference, I suppose it's logical it was done either way.

However, if the installer used the air gun socket and applied torque on the bolt head instead of the nut, it was done incorrectly. I would suspect that the designers intended the head to be at the rubber bracket, facing the sky when chassis set upright, and the nut below facing the ground when chassis set upright. When installed on the assembly line the intention was to torque the nut, which should have been facing the assembler. If the assembler used the opposite AIM method I doubt he put the gun under the flipped chassis to torque the nut. It'd be too much work. Torque applied to a bolt & nut assembly should be to the nut, not the bolt bolt head. I learned this many years ago from my limited mechanical engineering references.

Based on the consensus, it appears original cars have had the bolts in question installed either way, even though the AIM is specific in their orientation. For the record we were told the AIM is wrong. It is not. I feel our deduct/note or whatever we got spanked for was due to a misinformed volunteer.

Rich

[Gary J.]

Re: 1967 Lower Control Arm Rubber Bumper Mount Hardware

I look at a orginal '67 chassis yesterday and verify which way the nut was on the lower A arm bumper. The nut was on top.

[Donald H.]

Re: 1967 Lower Control Arm Rubber Bumper Mount Hardware

Related question.

The Judging Guide says the bumper is attached with a black bolt and hex nut. I don't see a lock washer in the AIM. ZIP and LIC sell the set of black bolts and nuts, and both have a lock washer at the head of the bolt.

Should there be lock washers?

Thanks,

[Jim D.]

Re: 1967 Lower Control Arm Rubber Bumper Mount Hardware

Related question.

The Judging Guide says the bumper is attached with a black bolt and hex nut. I don't see a lock washer in the AIM. ZIP and LIC sell the set of black bolts and nuts, and both have a lock washer at the head of the bolt.

Should there be lock washers?

Thanks,

Neither of my 65's left the factory with lock washers.

[Donald H.]

Re: 1967 Lower Control Arm Rubber Bumper Mount Hardware

Thanks,

Don

[Richard M.]

Re: 1967 Lower Control Arm Rubber Bumper Mount Hardware

Gary, thanks for the datapoint.

Don/Jim, As I recall the bolt "assembly" has a integrated LW. None on the nut end.

Ref photo of the LIC repros. I seem to remember originals are the similar configuration.

[Donald H.]

Re: 1967 Lower Control Arm Rubber Bumper Mount Hardware

Rich, after your thread, I looked at my just finished 66 restoration. I used the lower arm bumper bolt kit from Paragon, and it is wrong. Natural steel with a crimp nut, versus black phosphate and standard hex nut. I check Paragon, LIC and ZIP and all have the captive LW on the bolt. LIC and ZIP sets are as you pictured, black phosphate with captive/integral LW on the bolt/screw.

Per my 66 AIM, the bolt/screw is part number 3784302. Per a Google search, this part is described as - GM#3784302 is a 5/16"-18 x 3/4" in length with a 1/2" hex (AF) and integral split washer.

I just ordered the LIC set since I'm doing final adjustments to my car to take to the PA regional next week. Thanks for the insight.

Don

[Jim D.]

Re: 1967 Lower Control Arm Rubber Bumper Mount Hardware

Don/Jim, As I recall the bolt "assembly" has a integrated LW. None on the nut end.

You are correct. I was looking for a lock washer under the nut.

[Gene M.]

Re: 1967 Lower Control Arm Rubber Bumper Mount Hardware

Think about this logically. The access to tighten the NUT is open access from the bottom which being upside down is the top. One holds the bumper with the two bolts loaded in the holes, slips it into the holes of the A arm, starts the nuts and hits it with the air gun, done.

To do the assembly reversed would require a right angle air gun. Only and idiot would attempt torque the bolt head vs the nut. Did GM offer right angle guns to workers?

Logic says most installers would end up when right side up with bolts on top, nuts on bottom. But since the assembly guide does not state insertion direction it could possibly be reversed. Personally I've never found the assembly reversed on original cars restored in my garage.