54 shimms dont work

[Guy M.]

I just installed them and they make the 3rd arm hit the cross member mounting flange, Save youeself the trouble, dont do it. Theres nothing wrong with my third arm.

[Gary C.]

Re: 54 shimms dont work

Guy,

FYI - the '56 dealer retrofit mod that added shims to 56's also included a different 3rd arm to resolve the clearance problem.

Gary
....

[John H.]

Re: 54 shimms dont work

I just installed them and they make the 3rd arm hit the cross member mounting flange, Save youeself the trouble, dont do it. Theres nothing wrong with my third arm.

Guy -

That's why the third arm changed for '57, from part & forging #3706023 to part #3733215 (forging #3731801), to compensate for the geometry and dimensional changes that resulted from the addition of the caster shims.

[Tom P.]

Re: 54 shimms dont work

Can anyone show a side-by-side picture comparrison of the center steering arm so that the change in angle can be seen? Also, how about a comparrison of the early/later bracket for the steering arm?

[Gary C.]

Re: 54 shimms dont work

Tom,

Sorry, don't have any photos of an early 53-6 023 or 024 3rd arms.

The 56 retro mod dealer installed kit that added shims included the 511 3rd arm with spacers.

Attached are photo examples of the 511 3rd arm with 1/2" spacers on the rear bolts between the 3rd arm and front cross member. The 688 3rd arm basically adds the 1/2" spacers to the casting. IIRC correctly the 024 3rd arm has a thinner base plate than the 511.

Might want to search the archives.

Gary
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[Tom P.]

Re: 54 shimms dont work

Gary,
Your pictures are showing what I call the third arm BRACKET, but you're calling it third arm. I've always called the third arm (or center steering arm) that part which the tierods are connected to.
Now I'm confused. Which term is correct?

[Gary C.]

Re: 54 shimms dont work

Tom,

You're definitely the most experienced guy in 56-7 front suspension that I know of.

Looks like I've mistakenly referred to the Third Arm Bracket as the Third Arm and its attaching piece that goes to the steering box and tie rods the Idler Arm for years.

- P&A Group 6.186 Bracket-Bolt-Lock, Steering Idler and Third Arm, part # 688
- P&A Group 6.179 Arm Assy, Steering Idler and Third Arm, part # 1801

Sorry about that.

Gary
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[Jim P.]

Re: 54 shimms dont work

OK, now you fellas have me going out and looking at my steering assembly on my '53 which came out of a '54. I have the #3706023 Idler Arm, which is good, but my Bracket has been broken and brazed back together. Seems like I remember a thread on here talking about that bracket breaking easily, or doing some dumb stunt that would cause it to break. Does anyone remember that? Is that bracket a Corvette only part that I need to start looking for? Anything to do or not do when putting the correct replacement on? Looks like a simple bolt on to me.

Jim

[Tom P.]

Re: 54 shimms dont work

OK, now you fellas have me going out and looking at my steering assembly on my '53 which came out of a '54. I have the #3706023 Idler Arm, which is good, but my Bracket has been broken and brazed back together. Seems like I remember a thread on here talking about that bracket breaking easily, or doing some dumb stunt that would cause it to break. Does anyone remember that? Is that bracket a Corvette only part that I need to start looking for? Anything to do or not do when putting the correct replacement on? Looks like a simple bolt on to me.

Jim

Jim,
MANY, MANY people have used that bracket MANY times to place a jack under it for jacking up the front of the car with ZERO consequences. MANY people have stated MANY times-----------------DON'T DO IT, because there is a real possibility of it breaking (or a crack developing which can eventually lead to a break)! Tom Parsons is here to tell you also---------DON'T DO IT. I ALWAYS used to place the floor jack under that bracket to jack up the front of the 56. One day, 3 blocks from the house, it broke. If I want to jack up the front of the car, I place a wood block under the cross member on either side of the bracket to jack it up now. The place where the bracket breaks is just forward of the bearing. When it breaks, YOU'RE DONE. If it breaks at speed, you may be dead. Some of us dummies have to learn the hard way!!!!!!!!!!!!

Yes, the center steering arm bracket, center steering arm, L&R steering arms and the tierod tubes are specific to the 53-62 Vettes. BUUUUUUUUUUUT, as a complete assembly, they are a DIRECT swap to the 49-54 pass cars, which is an EXCELLENT improvement in steering for the 49-54 pass cars. Just changing from the kingpin/bushing setup of the pass car steering arm to the HD ball bearing of the Corvette steering arm will immediately and virutally permanently remove a lot of steering slack in the 49-54 pass car steering (and you guys with slack in your 53-62 Vette JUST THINK there is a lot of slack in your Vette steering ). I did this change to my 51 Chevy ~35yrs ago (maybe longer) and it still has tight steering. The ONLY adjustment I have ever made to the 51, as well as the 56 Vette, is adjustments to the steering box and the drag link per the ST12.

Oh ya, I would STRONGLY RECOMMEND that you have the brazed bracket welded by a highly experienced person that can weld cast iron, and then anneal it. It can be welded, and in my book it would be safe to use, but I wouldn't trust it after being brazed. That bracket is subjected to severe stresses from the steering.

[John H.]

Re: 54 shimms dont work

Gary,
Your pictures are showing what I call the third arm BRACKET, but you're calling it third arm. I've always called the third arm (or center steering arm) that part which the tierods are connected to.
Now I'm confused. Which term is correct?

Tom -

What you and I have always called the "third arm" is called "Arm - Steering Idler & Third" on its drawing (#3731801). The drawing is in Ken Kayser's "Countdown To Gold" article in the May, 2001 issue of "Vette Vues" magazine. There's no drawing of the previous third arm (#3706023), so I can't compare the dimensions that were changed when the caster shims were added.

[Gary C.]

Re: 54 shimms dont work

John,

3731801 is the cast number on the "arm" that attaches to the steering box. Attached is a good photo of the 023 "arm" from 56 VIN # 4026.

3731801 was used in conjunction with the shims 3733477, spacers 3733479 and bracket 3727511.

Attached a synopsis of the caster shims that Ken Kayser wrote for the 56-7 JM update.

Gary
....

[John H.]

Re: 54 shimms dont work

John,

3731801 is the cast number on the "arm" that attaches to the steering box. Attached is a good photo of the 023 "arm" from 56 VIN # 4026.

Gary -

Yup, that's what's commonly known as the "third arm".

[Tom P.]

Re: 54 shimms dont work

Well, now you all have me thouroughly confused!

FIRST, Ken's date-VIN in his letter don't jive. The 10-10-56 at VIN 4156 is Oct 10, 1956. In Oct 56, ONLY 57 Vettes were being built. VIN 4156 is 200+ cars before my 56 (4363) and my 56 was built on Sep 7, 1956 per Jack Knudsen's little note pad wherein he kept start-ending VINs for each day, which he wrote down for me at the 1981 NCRS Natls in St. Louis.

FRONT-BACK of his card.




I always thought the third arm was the center steering arm.
I thought the arm attached to the steering box (on the end of the sector shaft) was the pitman arm.
And I always had heard the adjustable link between the pitman arm and the center steering arm was called a drag link (but I know that's not the right term).

The bracket on the 56 for the center steering arm (as well as the one on my 51 Chevy) is 3742688 and the REAR of the bracket, where the 2 bolt holes are, is thicker than the front. I have a spare 3727511 bracket, with spacer washers at the rear holes, under the workbench. On the 511 bracket, the front and rear are the same thickness.
The center steering arm on the 56 (along with almost everything else) has been chrome plated, thus the casting number were ground off and polished. But the center steering arm under the workbench is 3731801. I do not remember where I got the spare bracket and steering arm.
I have another bracket and center steering arm in the attic. The bracket is 688 (thicker at the rear) and there is no number on the steering arm. Don't remember where these came from either.
So, which is the early bracket (thick or thin at the rear) and which is the later bracket (thick or thin)? And which bracket got the spacer washers and what year(s)?

[Gary C.]

Re: 54 shimms dont work

Tom,

56-7 JM page 85 chart lays out the transition VIN #'s for the various third arm brackets. Notice the chart is correctly named in the JM.

Would expect your car to have came with a 511 bracket, 1/2" spacers (between the bracket and front cross member) and a 1801 third arm.

688, which is a '57 part was available as the OTC service replacement part for years.

Gary
....

[Tom P.]

Re: 54 shimms dont work

Tom,

56-7 JM page 85 chart lays out the transition VIN #'s for the various third arm brackets. Notice the chart is correctly named in the JM.

Would expect your car to have came with a 511 bracket, 1/2" spacers (between the bracket and front cross member) and a 1801 third arm.

688, which is a '57 part was available as the OTC service replacement part for years.

Gary
....

DUH---------------------BINGO!!!
That's why my 56 has a 688 bracket on it------------------because it replaced the broken one!
I bought/chromed/installed the one which is on it now (688) and had the broken one welded and somewhere in the back of my mind (from ~35yrs ago) I sort of remember that it went on some other car.
Since I have a 511 under the work bench, I probably should install it and throw away the chromed 688 bracket ( ).