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So in looking to pick up a new center link as I start to acquire parts for a front end rebuild on my 64 Starfire, I see that you could have either TRW or Saginaw type steering setups. In trying to determine what type I have, this statement seems to be out there a lot...
If you are unsure which type of steering you have, you must measure the stud taper at the pitman arm end of the center link. The smallest diameter of the taper on TRW type centerlinks is .556 inches while the Saginaw type has a measurement of .587 inches.
This seems to be an pretty intricate measurement to take from a 56 year old greasy suspension part. Is there another easier way to determine what type system you have?
Unfortunately, not really.....
The two systems are NOT interchangeable... And they are what they are....
Oldsmobile bought from both companies back then -- they didn't think these cars would still be around 60 years later !!!! Their "job" was to get them into showrooms, as fast as possible....
So yes, the .556 versus .587 measurements are Critical....
Here is the Great News !!!! I have both Center Links and Idler Arms --- N.O.S. U.S.A. made ---
At way under the going rate $$$$ !!!!!
Always best to simply call me --- Craig --- 516 - 485 - 1935... New York...
Craig is correct. The factory put out this technical bulletin, but it only applies to the parts installed on the assembly line. Unless you have complete unbroken history on the car since it was born and know with 100% certainty that nothing in the linkage has been replaced in the last 55 years, measurement is the only way to know. And FYI, while this bulletin only talks about 61-63, that's because it was published in 1963. The 64 cars use the same parts as do the 63s.
Fusick has a useful drawing of exactly where to measure.
This seems to be an pretty intricate measurement to take from a 56 year old greasy suspension part. Is there another easier way to determine what type system you have?
Yes , look at the pitman arm ( that's the part attached to the steering box ) .
You should see a number forged on the bottom side of the arm.
If the number is a seven digit number , starting with 56 it is a Saginaw linkage . ( 56XXXXX )
-------- That ---- might ---- be okay, if it is Saginaw and has markings.....
The foolproof method of success is still:
.556 = " Alternate or TRW design ". Versus
.587 =. Saginaw Design....
You don't want to be shipping Center Links & Idler Arms & more.....
Back and forth and Back and forth....
It pays to be PERFECT right from the start.......
-------- That ---- might ---- be okay, if it is Saginaw and has markings.....
.
If it is a Saginaw pitman arm , it WILL have a 56XXXXX number forged on it .
Saginaw was a division of GM . and each division had a two digit prefix to the part number .
56XXXXX was used by Saginaw , 31XXXXX was used by Harrison Radiator , 51XXXXX by Detroit Diesel , 59XXXXX by Guide lamp , etc .
This , of course , was before the the advent of eight digit GM part numbers .
Last edited by Charlie Jones; May 18th, 2020 at 05:01 PM.
This is interesting CSI stuff here LOL. I am surprised it would be as easy as looking for the "56" and the "S" stampings. I would think, of course with that err of caution since I do not know the entire suspension history of this car, that if you have these parts, you would have the Saginaw setup. I suppose tie rod ends could have been replaced along the way, but the pitman arm is sort of a lifer?
So it got me thinking, does this really matter at all if you change everything? Tie rods, pitman arm, idler arm, and drag link. If I were to buy all 7 parts of one style...or the other....and put them on, I should be OK?
I should add that I am looking to do a whole suspension rebuild, not just the center link. So I wouldn't be wasting money on extra parts since I planned to replace them anyway.
I also know these 394s had two different oil pans. Is that a factor with the replacement parts?
So it got me thinking, does this really matter at all if you change everything? Tie rods, pitman arm, idler arm, and drag link. If I were to buy all 7 parts of one style...or the other....and put them on, I should be OK?
Yes, so long as the tapered holes in the pitman arm and idler arm match the tapers on the center link, you're fine. The problem is that you won't find the pitman arm. That's not a normal wear item and replacements were not readily available.
I believe I do have all 8 eight items for both set ups that you would want:
The (1) Center Link
The (1) Idler Arm
The (2) Inner Tie Rods
The (2) Outer Tie RodsThe (2) Tie Rod Sleeves
Those are the 8 replaceable parts of your car's Steering Components...
The PITMAN ARMS , as our most knowledgeable leader, Joe P. Pointed out,
Is a Non - Wear item, and remains "as is".
Everything I have is N.O.S. U.S.A. made --- no Wuhan / Chineseum !!!!!
On Power steering cars, YES, the oil pan with step in sump is a different center link again!!!!!
to bypass the oil pan.....
And, I have the second design center links N.O.S. U.S.A. made also .... Life is great.....
Yours, Craig.....
With Joe P. and Charlie Jones supplying mega information, and me with confirming information and all the parts,. You couldn't be in better hands ( on unfortunately, a very prickly situation -- not any of our faults!!!!! It is what it is......)
Last edited by mpolds; May 20th, 2020 at 10:21 AM.
Reason: Add on
Thanks for the great info guys! I hope to crawl under tomorrow to verify what it is exactly that I have. As to the oil pan and the stepped vs. non-stepped version, I guess I was picturing this as a type of horizontal, well, step, or lip. But is it the two 30 degree or so bends in the pan that are called 'steps' for the steering clearance? This is a 1964 88 stock internet picture, showing these 'steps'...
And in this picture (from Charlie Jones posts here in 2018 of I believe a 1963 394) would be showing the non-step version?
Yes that picture was a 1963 Starfire engine .
That pan would be the same as the early '64 pans .
What you have is the later '64 pan .
Since the TSB mentioned in the parts book is dated Nov . 1963 , I would think the change occurred about then .
Now , what's the number on the bottom of the pitman arm ?
So I was able to look at my Pitman arm and it would appear to not be the Saginaw type, as the only number i can see is the larger one. Is the Saginaw 56XXXXX large like this, or smaller?
I also found this related to the idler arm. Or is this part interchangeable?
I appear to have an alternate type...
Based on these things, I'm leaning toward the TRW setup? Are there any other clues, such as the plant the car was assembled at, or the VIN number? For example if it is a high VIN, could one assume it was a second type, as they had switched by then?
Hey. Awspeich,
Not that I know of .... I have always been a fan of the .556 vs. .587 !!!!!
Let's see what Charlie Jones and our illustrious leader Joe Padavano say....
I am leaning toward your belief that this would the be the:
TRW = Alternate Design = .556 ......
Hopefully, Charlie and Joe P. Will comment today....
(In the meantime, you might want to see if you have that "step in sump" of the oil pan
For 1st design versus. 2nd design .......
Yours, Craig 516 - 485 - 1935.....
That pitman arm does not have a Saginaw number .
That and the idler arm tell me it is an alternate / TRW steering system .
As far as I know , there was no rhyme or reason as to which cars got either type .
I suppose it was whatever was available at that assembly plant on that day .
Saginaw was a division of GM . TRW was an independent company .
Okay, we have three of our four precincts reporting TRW / Alternate , with one precinct yet to report -- Joe P.
The no rhyme or reason is correct ... What I had heard, years ago, but I can't substantiate it's validity (and the correct people to ask have all passed now...) was that Saginaw could not make them fast enough, so they called in "an outside vendor -- TRW" to make them....
But, unlike other situations, where then it is car # xxx through car # yyy , and after car # yyy ,
It is not.... So I think the final answer, is, who knows ?!?!? I guess it "is what it is !!!"...
Yours, Craig.....
Last edited by mpolds; May 26th, 2020 at 06:40 PM.
Can you guys help me with one last thing....the oil pan. I guess I'm still not clear what the first type and second type for 1964 394's looks like. Below is a picture of what I believe is a 2nd type, stepped version? Would that be correct? Just want to make sure I have the right combo of TRW parts and oil pan. Thanks!
Hey Al / Awspeich,
That sure LOOKS like the step in sump Oil Pan...
We need Joe P. And Charlie Jones to chime in and confirm.....
Hey Men, what do you say ???? Agreed ????
Yours, Craig......
Can you guys help me with one last thing....the oil pan. I guess I'm still not clear what the first type and second type for 1964 394's looks like. Below is a picture of what I believe is a 2nd type, stepped version? Would that be correct? Just want to make sure I have the right combo of TRW parts and oil pan. Thanks!
Of course, all the time and effort we all took to confirm everything for Al / awspeich --
Four months ago, May 30, was the last time he has been on Classic Oldsmobile, period....
And, obviously, has NEVER come back here.
He was from South Carolina, and they have had a serious "2nd wave" of coronavirus.... I hope
Al / awspeich isn't DEAD.....
Hey Brad,
I would certainly agree....
I looked up your Center Link.... Planning on getting to my building tomorrow... Ran out of time today .... Will talk to you tomorrow.... Yours, Craig.....
Of course, all the time and effort we all took to confirm everything for Al / awspeich --
Four months ago, May 30, was the last time he has been on Classic Oldsmobile, period....
And, obviously, has NEVER come back here.
He was from South Carolina, and they have had a serious "2nd wave" of coronavirus.... I hope
Al / awspeich isn't DEAD.....
Just a quick note to say that, yes, I am alive. Life has been ...interesting..since I asked all these questions about the steering setup. I hope the thread adds value to others who seek out the information in the future. And thanks again for all who researched the issue and commented. Craig I'll also reach out to you regarding these parts. Thanks! - Al
Gang,
I came across this diagram today from one of my 1966 parts books. I think this may help tell the tale. 1966 Olds Parts Book diagram of Thompson vs Saginaw steering parts
A piece of trivia which may interest some of you is that Thompson was the "T" in TRW which was built into a conglomerate of many businesses from aerospace to (surprise) auto parts. TRW eventually bought a credit bureau which became TRW credit bureau and has since become Experian whose commercials you may see on TV even today.
Chris, that diagram is unfortunately only applicable if one is certain that the parts are OEM. If they have been replaced in the last half a century, aftermarket replacement parts may or may not look like those originals.
When I was interviewing for a job after college, TRW in Redondo Beach was one of my stops. I was especially taken by the fact that across the hall from the cafeteria there was a counter with a complete parts store TRW automotive catalog. Apparently employees were able to order parts directly at factory discount. Needless to say, that was an enticement, however I ended up at Hughes Aircraft up the street instead.
A piece of trivia which may interest some of you is that Thompson was the "T" in TRW which was built into a conglomerate of many businesses from aerospace to (surprise) auto parts. TRW eventually bought a credit bureau which became TRW credit bureau and has since become Experian whose commercials you may see on TV even today.
Some of the world's largest consumer data breaches were via Experian. Shoved under the carpet now by most media outlets. Those data breaches I believe still represent the largest consumer personal identification data breaches in the world.
But be clear, Equifax and Trans Union are not better.
The US has made some very anti-consumer decisions in the name of commerce and growth. Most of the world are much more careful about consumer privacy than we are.
I was deep in that world for many years. And worked directly with, but not for, Experian for 5.
I installed enterprise global network monitoring & management s/w both in the private & public sectors. How well the customer employs the s/w is up to the customer.
May 17th, 2020, 09:26 PM
