Compatibility of front control arms/spindles
 

I have a 70 GMC and have upper/lower control arms and drop spindles from a 1972 chevy. When I look at parts books like LMC or brothers, these parts are different for the years. I am not sure what is different.

Is there any way to use the control arms and spindles on my 70? What parts may I need to get? Tie rods inner/outer, engine crossmember?

Re: Compatibility of front control arms/spindles
 

Just found my answer and a couple days of looking. http://67-72chevytrucks.com/vboard/s...ad.php?t=13692

Re: Compatibility of front control arms/spindles
 

Some additional information in my signature.

Re: Compatibility of front control arms/spindles
 

Thank you for the reply. I found your posts earlier. Very good info. The parts I currently have off a 72 are - drop spindles, rotors, upper and lower tube arms with the boots, coil springs.

I currently have drop spindles and disc brakes on the front with original arms and spring. The arms have been messed with by the PO.

With my original cross member will the tube arms bolt up OK? Then I can get outer tie rods and tie rod adjusting sleeve made to convert from 67-70 threads to 71-72 threads? Some one posted part # CPP CP4SC-SAP for sleeve. But that converts to a 73+? Any idea if they make one to convert to 71-72?

Re: Compatibility of front control arms/spindles
 

Just noticed this on your thread :
Tie Rod Adjusting Sleeves
Grouped by Differences:
C10 and C20
*60-64
*65-70 (5/8" thread)
*71-87 (11/16" thread)

So would the CPP part work - even though they sat converts a 70 to a 73+?

Re: Compatibility of front control arms/spindles
 

I am not sure where you are getting your info, or IF it is correct, not trying to sound like a Beavis, just to help!!!

I CAN tell you that (without doubt...) 67-70 steer linkage is ALL different from 71, 72 linkage, AND those are ALL different from 73-up steering linkage.

HOWEVER...The control arms are all the same from 67-72. Your 72 upper AND lower control arms will bolt up to your 70 cross member.

67-72 Pitman arms are same,(Power steering, remember manual takes a different pitman arm, 68-72 manual pitmam arms are same, not sure why 67 is NOT included. 73-up pitman arms are another part number

67-82 Idler arms are ALL same!!!

The thread sizes on the threaded end of the tie rod ends MAY be the same (My experience tells me, IT IS NOT), BUT also the tapers on the tie rod ends are not the same. The tapers are larger on the 73-up tie rod ends. 71 and 72 tapers are the same , BUT also different form 70 and earlier.

I do NOT know if the aftermarket makes "conversion" tie rod setups for the 71-72 spindles. The only way I know to use the 71-72 spindles is to use ALL 71-72 steering linkage...

Re: Compatibility of front control arms/spindles
 

I just completed a 70 C30/35 to 86 Disc Brake Conversion and the 86 tie-rod ends... ARE... the same taper as the 70. I reused my 70 center link with a 70 Pitman Arm, a 70 Idler Arm and 86 tie-rod ends inner and outer, they are the same taper and fit perfectly.

Now the 86 center link which is a different length, about 1-1/4" shorter than the 70 at the Pitman, Idler taper centerlines and 1/2" shorter at the tie rod tapers, cannot be used...it does have one size smaller Idler Arm Taper, but the frame Idler brackets are the same taper.

Here are my notes I posted on what I used to complete my conversion:
http://67-72chevytrucks.com/vboard/s...light=sheepdip

Re: Compatibility of front control arms/spindles
 

Glad to hear that. I am going by part numbers, AND knowledge...from my end. Hope that helps the OP!!!

Re: Compatibility of front control arms/spindles
 

Thanks for the info and confirmation. Everything I have read and seen on this site as well as in catalogs - the steering linkage is different from 67-70 to 71-72. But like you said the pitman and idler are the same for all years.

What I can tell is the threads and size on the tie rods are different on the years - so either have to replace the whole linkage or get outer tie rods for a 71-72 and a thread converter. However, the CPP thread adapter says it Accepts 73-87 outer tie rods and 63-70 inner tie rods.

So questions:
1. Are 71-72 outer tie rods same as 73-87? to be able to use the thread adapter by CPP. Vs changing completely over to 71-72 linkage
2. Is the engine crossmember the same 67-72?
3. The tubular control arms are different part numbers 63-70 and 71-72? Does this have to do with the boots? What makes the tubular different from stock control arms? The stock control arms are the same for the years.

Re: Compatibility of front control arms/spindles
 

I was looking at parts catalog and seem to remember seeing that there was a difference with C10 vs C20 to C30? Could you findings be a little different since you have a C30?

Re: Compatibility of front control arms/spindles
 

WOW. Lots of conflicting info here.

1) The problem with tie rods are that there are two ends to measure.
The threaded end and the tapered end.
The conversion tie rod sleeves convert from 5/8” to 11/16” thread.
( the tapered ends are different also from 63-70, 71-72, and 73-87)

But the real confusion is that the 63-70 OUTER tie rods are LH THREAD.
71-72 and 73-87 OUTER tie rods are RH THREAD.
So to keep a 63-70 centerlink with the later disc brake outer tie rod ends (71-72 OR 73-87) and keep the thread pitch compatible,..
You need to use a 63-70 OUTER tie rod in the INNER location.
This will allow you to use the 71-72 or 73-87 OUTER tie rod to match whichever year spindle you are using.

Not sure why companies list he conversion tie rod sleeves at 73-87. Because 71-72 outer tie rods are also 11/16” diameter.

2) crossmember is the same with the exception of the steel brake line tab location.
Behind the crossmember on 63-70 trucks.
In front of the crossmember on 71-72 trucks.

3) the tubular control arms have different part numbers because of the different ball joints that are used. The arms themselves are the same.

Re: Compatibility of front control arms/spindles
 

C20 and C30 upper a-arms ar the same design, different balljoint as the C10’s.

The c20/c30 LOWER a-arms have a physically different size hole for the lower balljoint. Bigger than a c-10 lower a-arm,... but still the dame design.

Re: Compatibility of front control arms/spindles
 

Centerlinks MAIN DIFFERENCE is the taper of the hole for the inner tie rods.
That’s why the break down of differences.
63-70
71-72
73-87

Re: Compatibility of front control arms/spindles
 

1) yes

2) yes. Read post below about match thread pitch direction.
You have to have a RH/LH assembly. So use 67-70 outers at the INNER location. Then screw a 71-72 outer at the OUTER LOCATION to match your spindle.

3) use the one that says 73-87. It’s the same 11/16” diameter as your 71-72 tie rod.

BUT ALL OF THIS MISMATCH OF PARTS COULD BE ELIMINATED IF: you would use direct bolt on 63-70 conversion spindles.

You decided where you want to spend your money.
New spindles? Or buying a bunch of parts to make what you have work.

Re: Compatibility of front control arms/spindles
 

Keith, I don't doubt your expertise in these conversions, in fact I used a lot of info you provided, but I can tell you that the 73-87 tie rod tapers are the same as a 70, at least on a C30 they are. I reused my existing 70 center link, 70 idler and pitman and tie rods inner and outer were 73-87, they were the same taper and fit perfectly, the truck computer aligned perfectly after the install.

Like I stated in a earlier post I just completed a front disc conversion from an 86 to my 70 leaving my 70 cross member in place and bolting 86 upper and lower control arms to it.
I found the 86 center link to be roughly 1-1/4" shorter at the pitman/idler taper center lines and 1/2" shorter at the tie-rod taper center lines than the 70 center link.

Not sure what year the break occurred but the idler arm taper on the 86 was also 1 size smaller. Also I'm not sure why the 86 center link is shorter but it has to be in the steering box/idler arm center lines... I did not have the whole truck to measure why the discrepancies.

Re: Compatibility of front control arms/spindles
 

Man thank you so much! Awesome info! You may be right about all of the mismatched parts.

My 70 already has front drop spindles with disc in front with original beat up upper and lower arms and drums in back. I was mostly trying to see how I could somehow use the upper/lower tubular arms from a 72.
If I could just use the tubular arms and they bolted directly up to my current spindles and leave my tie rods alone that would be great.

Re: Compatibility of front control arms/spindles
 

Keith, My goal is to see if I can use the CPP tube arms from a 72 C10 on my 70 to replace the stock arms. My 70 has drop spindles already.

Sounds like using my 70 ball joints (or buying new ones for a 70), my 70 drop spindle, and not messing with my 70 linkage - the upper/lower tube arms will bolt up fine?

Re: Compatibility of front control arms/spindles
 

Do you know for sure what year spindles is on your 70 now?
63-70 conversion spindles?
70 trucks were drum brake.
Maybe someone has converted it with 71-72 parts already.

You have the truck.
Pull it apart and see.

The least you could do is swap 70 ball joints in the tubular a-arms.
I don’t know what parts are on your truck.
You are going to have to figure that out to get a real answer.
Everything from me is just a guess.

Re: Compatibility of front control arms/spindles
 

That did cross my mind. I'm going to pull the the wheel off this weekend. Is there any way to visually tell? I would think that if someone were to add drop spindles the easiest thing would be to just do the spindles for the correct year. I know the ball joints have been replaced. But over 50 years and a few different owners who knows.

Re: Compatibility of front control arms/spindles
 

True, but that may not have been cost effective for what THEY were doing. Perhaps they got the spindles for free...

Re: Compatibility of front control arms/spindles
 

LOL! who would ever do that? That is exactly what I am trying to do! Haha.

Re: Compatibility of front control arms/spindles
 

So do you think in my case maybe get some new 1970 ball joints and compare them to the ball joints in my 70. If the angles are the same then it was a 70 adapter spindle. If not a match then next best guess would be to get a 71-72 ball joints and compare angles? then 73+ ball joint..... geese this was supposed to be simple. Gotta be sherlock on some of this stuff. I really appreciate everyone on here sharing knowledge and helping.

Re: Compatibility of front control arms/spindles
 

That would be my approach. I would purchase parts for all 3 possibilities from my local parts store w/their buy-in (talk w/a manager). Sort & test the fit. Return what you don't use.

I've had to do it this way more than once trying to sort through what someone else did. It's also a reason I include a folder w/info when I sell a vehicle I've worked on/built.

Re: Compatibility of front control arms/spindles
 

Out of the blue Van at CPP returned my call from last week re using 72 tube arms, boots and drop spindle on my 70. He said that as long as everything on my 70 is really 1970 then this is the following to make it work.

Bolt up the 72 tube arms, use the 72 boots and 72 drop spindles. Then buy 1971- 1972 outer tie rods and buy CP4SC-SAB converter sleeve. Replace my inner 1970 tie rods with my outer 1970 tie rods and use the outer 71-72 tie rods to attach to the drop spindles. He thought this would be the cheapest/easiest way to switch everything.

I'll post once I get into it here a let everyone know how it works or doesn't work!

Re: Compatibility of front control arms/spindles
 

I think you have it figured out!
Now you are the expert on this subject.
I’ll count on you to pass this info on to others.
Because this subject WILL come up again. :metal: