63 trailing arm originality

[Jim D.]

Re: 63 trailing arm originality

I agree Joe. If you can't do them yourself, have them done by someone that knows what they are doing. Unfortunately, Frank had posted on the CF that his were rebuilt by a very experienced builder and had recommended that person to many others. I only hope that if others followed his advice, they had better luck.

[Joe L.]

Re: 63 trailing arm originality

Frank, this spindle bearing support is from July 1, 1963. If the N was not in the casting number it would be July 1, 1973. I do not call when the N was eliminated. One of mine is after the build date of the car. I found a good date but the labor to swap parts is too much. I'll wait till I really have to change it.

There was also an NF and I can't recall what that was all about.

[ATTACH=CONFIG]99886[/ATTACH]

[ATTACH=CONFIG]99887[/ATTACH]

Harry------


The "N" was never eliminated but it was "added to". All 1963-74 Corvettes used rear spindle support GM CASTING #3820643. Early 1963 have no webbing between the "legs". Later 1963 through 1974 do have the webbing although the casting number did not change when this was added. All have the "N" suffix of the casting number. At some point early-on an "F" was added to the suffix. I do not know just when this happened; it may or may not be coincident with the addition of the webbing. Why it was added I know not. The The "N" represents nodular iron. The "NF represents nodular ferris which I believe is the same material. There may be some distinction, though, of which I am unaware.

The casting is symmetrical and the same casting number was used for both sides. However, the machining and finished part number were different for each side. This related to which "leg" received the D-shaped machining. The left side finished part number was the same as the casting number. The right side finished part number was 3820644.

The supports changed for 1975-82. The bosses on the lower end were enlarged but the supports otherwise remained the same. These carried casting number 348103 still with the "NF" suffix. Following the pattern set earlier, these were finished part number 348103 for the left side and 348104 for the right side. These supports also became SERVICE for 1963-74 in 1976.

[Gary R.]

Re: 63 trailing arm originality

Frank
I just took a look at your video. You are getting play in the 6 & 12 position, which may be showing from the inner axles. How is it at 3 & 9?

You said they were done recently, if done correctly they should not be showing play like that. Do you recall if there was any play when you installed them? I am not saying they were incorrectly setup but you should confirm the play is in the outer axle and not the inner.

The book spec is 001-008" which is about a long as a mile in precision setup. If you grab a wheel stud and can push/pull on it and you feel movement you have at least 003 endplay. Many people set these up all through the spec range, in theory they are all correct. I set mine up without lateral play in them,which ends up about 001-0015" endplay which is subjective to the person applying the force and the method used to check the endplay. Drum brake cars are more forgiving with endplay then disc brake setups with lip seal calipers. Correctly setup they should be smooth and even slightly snug once assembled and greased. Now that is with stock 17 spline axles, I just setup a set of 31's today in fact and they are set to a slight preload without any issues.

If you want to go over any questions let me know, I will be in my shop finishing up those 31's tomorrow.

Since you have your car on the lift, before I would pull the arms I would pull the 1/2 shafts and isolate the play. Without the shaft connecting the inner and outer axles you can check the outer endplay and see if there is clunk there. Then check the inners. Many 63-64 diffs were rebuilt or swapped out over the years. If yours was worked on and later C3 axles used you might have some axle face wear and that would explain the 6& 12 movement. Inner axle endplay comes from 3 area within the diff.
1- axle face wear
2- posi setup
3- cross shaft holes opened up.
Most times it is 1 and or 2.

If you do feel the play and clunk while the shafts are out then there is only the axle and bearings. You can check the axle nut, it should be torqued to 100+ Ft/lb. Sometimes rebuilders try to compensate for incorrect bearing setup by not holding the 100 ft/lb rating. There is also a cupped washer under the nut, this is a 1 time part so it should be replaced every time the nut is loosen since they flatten out. The crown goes to the nut.

If you want to go over these checks, let me know. I will be in my shop finishing up those 31's for my buddy.

[Frank D.]

Re: 63 trailing arm originality

Appreciate it Gary - I'll do some more research on your suggestions today...
I have receipts from decades ago where an Eaton posi was installed so, yes, the differential, has been "gone into" before -- at least once.
I'll print out your post and use it in the shop today - thanks.

The trailing arms were done almost exactly two years ago and set for the tighter end of the spec, I want to say .002 but its been a while..
Timken bearings were used.

[Harry S.]

Re: 63 trailing arm originality

Thanks Joe, but could swear that I have seen several sets over the years with the N or F. Oh well.

[Timothy B.]

Re: 63 trailing arm originality

Hi Frank,

I would do as Gary say's and isolate the axle from the rear pumpkin (inner axle) to see if there is any abnormal movement in/out, the bearings may be fine. Are you certain the new emergency brake cables are releasing completely, brake shoe not dragging on the backing plate, brake drum not round etc.

It probably does not take much for 20* temperature rise in summer temps, go have a beer and think about it for a bit and if you can't justify bad bearings get another set of eyes on it first.

[Frank D.]

Re: 63 trailing arm originality

Yup - Did all that yesterday. With the half-shafts off, the differential flanges have no lateral play and a slight (VERY slight) in/out movement and in talking with Van Steel and Gary all is well and easily within specs and by design. The inner bearings move smoothly and quietly and are easily turned by hand - all good there. No leaks and I had changed the pinion seal this spring.

It also appears the trailing arms are good. Van Steel offered to check them out (no charge) and I'll carry those (along with the half shafts) over to Clearwater today and also use it as an excuse to have lunch with daughter (works in St. Pete). Van Steel said to bring the half shafts for a look-see as well in regards to the noise/movement in the video above...

All this does make me miss my solid-axle 61 a bit...certainly been a learning experience...

Car has new shoes, new ACDelco "Professional" drums (very nice pieces), new, rubber hoses, new brake spring and self adjuster kits, I'm pulling the original wheel cylinders out of storage and will rebuild and dump the Dorman aftermarket versions. We'll see.

[Harry S.]

Re: 63 trailing arm originality

Frank, now you can check the dates on the bearing supports.

[Frank D.]

Re: 63 trailing arm originality

Frank, now you can check the dates on the bearing supports.

And do some serious detailing in hard-to-reach spots, are your rear leaf springs a "light gray" as the 63 JG states ?

[Harry S.]

Re: 63 trailing arm originality

Yes,

63 Rear Spring Restored 004.jpg

[Frank D.]

Re: 63 trailing arm originality

Thanks. Some previous owner painted everything under my car's rear with barbecue grill black paint; including the spare tire tub (which I've corrected)..

[Frank D.]

Re: 63 trailing arm originality

I agree Joe. If you can't do them yourself, have them done by someone that knows what they are doing. Unfortunately, Frank had posted on the CF that his were rebuilt by a very experienced builder and had recommended that person to many others. I only hope that if others followed his advice, they had better luck.

You're assuming they were done incorrectly and I will have Van Steel look them over today....as a second check; as Gary R. responded to me yesterday, with the half-shafts disconnected, there is nothing involved except the bearings and they work smoothly, with minimal play vis a vis Gary's "wheel stud" check and no clunk-clunk.

I suggest you be more circumspect with your remarks about people whose skill set you don't even know...

[Frank D.]

Re: 63 trailing arm originality

Starting to bolt things back together today - I don't think I've mixed them up but is there an obvious way to tell the left and right shock mounts ?

[Larry M.]

Re: 63 trailing arm originality

Starting to bolt things back together today - I don't think I've mixed them up but is there an obvious way to tell the left and right shock mounts ?

Part number of derivative of part number if stamped on mount. Odd # is driver side.

Larry

[Frank D.]

Re: 63 trailing arm originality

Perfect. I know that's the usual convention but thanks for confirming... One mount # ends in "29" and the other in "30" so I had them right anyway.