1965 Differential Cover

[Mark P.]

When I bought my car the lower ears on the differential cover were welded after I assume someone broke them by torqing the 4 bolts down tight before loading the spring properly.

Is this very common ?

I plan to lightly tighten (i.e. 10 lbs) and attach the spring to the trailing arms but not torque them the rest of the way until the car is on the ground. Is that the right way to do this ?

My car was built in early February. It does not have heavy duty brakes. What is the right casting number ?


Are there any dates on the cover ? Any good source to locate one ?

[John H.]

Re: 1965 Differential Cover

When I bought my car the lower ears on the differential cover were welded after I assume someone broke them by torqing the 4 bolts down tight before loading the spring properly.

Is this very common ?

I plan to lightly tighten (i.e. 10 lbs) and attach the spring to the trailing arms but not torque them the rest of the way until the car is on the ground. Is that the right way to do this ?

My car was built in early February. It does not have heavy duty brakes. What is the right casting number ?


Are there any dates on the cover ? Any good source to locate one ?

Mark -

I've never seen one that's been welded, but I've heard of that repair being done successfully.

The procedure for torquing the bolts you noted is the correct way to do it.

I don't recall the changeover date between the earlier 303 rear cover and the later 375 cover; someone else may have it.

[Joe L.]

Re: 1965 Differential Cover

When I bought my car the lower ears on the differential cover were welded after I assume someone broke them by torqing the 4 bolts down tight before loading the spring properly.

Is this very common ?

I plan to lightly tighten (i.e. 10 lbs) and attach the spring to the trailing arms but not torque them the rest of the way until the car is on the ground. Is that the right way to do this ?

My car was built in early February. It does not have heavy duty brakes. What is the right casting number ?


Are there any dates on the cover ? Any good source to locate one ?

Mark-----

I wouldn't use a weld-repaired cover. The covers are dated and the usual "6 month rule" applies. Most 1965's used the 3871375 cover. It should not be too difficult to find one of these covers. However, finding one properly dated might be more difficult. Ikerd's Corvette in Bedford, IN is a good source for used examples of these covers.

[Jim D.]

Re: 1965 Differential Cover

My April 65 has the 375 cover.

[Mark P.]

Re: 1965 Differential Cover

Here is a photo of my welded cover. You can kind of see the welds.

https://www.forums.ncrs.org/attachment.php?attachmentid=16714&d=1237127379&uid=6614

I don't want to reuse it. I'll look for the 375 cover.

I am going to send my trailing arms out to be rebuilt due to a bearing that just failed. I was also going to get my half shafts rebuilt.

Since I have no history of the work done on my car over the years then I was thinking of having someone go through my differential and replace what needs replacing.

Since I will have the spring removed from the trailing arms and half shafts removed, do you think it is worth doing this now ?

Is it much extra work to remove the differential at this point ?



Thanks,

Mark

[Mark P.]

Re: 1965 Differential Cover

I spoke with Ikerd's and they had a 3830303 cover with the fine threaded plug with a K 25 64 date. Would that be Nov 25, 1964 ?

Any issues using that for a Feb 4, 1965 car or should I hold out for a 3871375 cover with an A date ?

I need to look at the numbers on my existing cover and the rest of the dates on my differential to decide what to look for.

Has anyone heard of much variation in dates between the differential case and the cover ?

Thanks,

Mark

[Joe L.]

Re: 1965 Differential Cover

Here is a photo of my welded cover. You can kind of see the welds.

https://www.forums.ncrs.org/attachment.php?attachmentid=16714&d=1237127379&uid=6614

I don't want to reuse it. I'll look for the 375 cover.

I am going to send my trailing arms out to be rebuilt due to a bearing that just failed. I was also going to get my half shafts rebuilt.

Since I have no history of the work done on my car over the years then I was thinking of having someone go through my differential and replace what needs replacing.

Since I will have the spring removed from the trailing arms and half shafts removed, do you think it is worth doing this now ?

Is it much extra work to remove the differential at this point ?



Thanks,

Mark

Mark------


That cover not only has the welds but it also has serious corrosion damage. The rust has been cleaned off leaving the serious erosion of metal. It's UGLY. I'd junk that thing in a second. I'd concentrate on getting a good, non-repaired, non-corrosion damaged cover. If it were me, I'd worry less about date than getting a good cover.

Once you have the spring, trailing arms, and half shafts out, removing the differential carrier is as simple as disconnecting the driveshaft, removing the forward snubber bolt, and lowering the crossmember with differential carrier attached.

[Joe L.]

Re: 1965 Differential Cover

I spoke with Ikerd's and they had a 3830303 cover with the fine threaded plug with a K 25 64 date. Would that be Nov 25, 1964 ?

Any issues using that for a Feb 4, 1965 car or should I hold out for a 3871375 cover with an A date ?

I need to look at the numbers on my existing cover and the rest of the dates on my differential to decide what to look for.

Has anyone heard of much variation in dates between the differential case and the cover ?

Thanks,

Mark

Mark------


The date is November 25, 1964 and would work as far as NCRS and NCCB guidelines are concerned for your car. A 3830303 cover is usually a LOT harder to find than a 3871375. In what kind of shape is the cover you've been offered? Corrosion damage? If so, I'd definitely pass on it.

If your car currently has a 3871375 cover that's been repaired, the chances are that your car was originally built with that cover (check the date on it to be sure). In that case, I think I'd look for another 3871375. Among other things, they are easier and cheaper to find.

[Wayne M.]

Re: 1965 Differential Cover

I spoke with Ikerd's and they had a 3830303 cover with the fine threaded plug with a K 25 64 date. Would that be Nov 25, 1964 ?

Any issues using that for a Feb 4, 1965 car or should I hold out for a 3871375 cover with an A date ?

I need to look at the numbers on my existing cover and the rest of the dates on my differential to decide what to look for.

Has anyone heard of much variation in dates between the differential case and the cover ? ....

I'm sure Ikerd's has seen a lot more diff. covers than I have (and I've heard of a '303' dated cover -- maybe it was the same source), but IMHO, covers were not dated before the C3 era. See link of previous discussion, below:

https://www.forums.ncrs.org/showthread.php?t=79136&uid=2547

Also, big pic(s) are of the '303' off my early '65 VIN 014xx, 4.11's assembled AP-9-17 (Sept 17th). It is a hybrid as it has the 2nd design NPT plug [I show the threads, compared to the '63-4 style (fine) [3rd big pic].

[Mark P.]

Re: 1965 Differential Cover

I checked the differential cover and it is a 3871375. I see no date and the JM does not mention one so that makes it easier to find. I will start calling around asking for one.

My differential cast date is A 16 5 so this is January 16, 1965 and precedes my car build date by 2.5 weeks. The assembly date looks like 1 ?? 5 so it was some time in January. The corrosion has made it so I can't make out the day of the month.

[Russ S.]

Re: 1965 Differential Cover

I welded both lower tabs on my 73 about 30 years ago and they are still fine even with auto crossing the car for a couple years. With a good weld mine are stronger than before they broke but it's hard to tell if your weld is good or not being you don't know any thing about who or how it was done.

[Mark P.]

Re: 1965 Differential Cover

I found a cover and it looks in good shape except for this hole in the casting because someone used too long of bolts.

Should I find another one, or should I just use it as is ?

Should I get it welded or repair with JB Weld ?

I paid $100 off EBAY. Should I just return it ?

Thanks,

Mark

[Russ S.]

Re: 1965 Differential Cover

If it is the right numbers I would(if you have room) screw a set screw all the way into the hole from the outside and then have it welded. You would need to make sure you have enough depth for the bolt after you put the set screw in.

[Wayne M.]

Re: 1965 Differential Cover

If it is the right numbers I would(if you have room) screw a set screw all the way into the hole from the outside and then have it welded. You would need to make sure you have enough depth for the bolt after you put the set screw in.

(Mark) -- Wow; I hope seller described that defect. Those things weigh about 25 lb boxed, so return freight will be a real hit.

(Russ) -- looking at Mark's pic, I see that the missing chunk has already cost about 5 effective contact threads, so welding would subtract at least that number from the available.

[Gary R.]

Re: 1965 Differential Cover

I wouldn't use that cracked cover.