Steve59

Over the last two years, I've had an engine, trans, and rear built for my 59. I'm now planning on installing those assemblies. The first I'm going to do is the trans, the one presently in the car will not stay in 4th gear. So that trans will be replaced. Of the three, it's probably the easiest to do.

I'm familiar with the difficulties and problems associated with engine and trans swaps but haven't a clue as to what to plan for or what I will encounter in the rear swap. This will be a drum to drum swap. What's in the car now is a 3.70 open, what will go in is a 3.70 posi. Any thoughts or advice from guys who have done this type of swap would be appreciated.

wmf62

Changing the 'pumpkin' is as simple as pulling the axles and then removing the differential (pumpkin). Reassembly is the reverse EXCEPT that you might have to shorten the drivers side axle an 1/8 - 1/4" if it doesn't slide all the way in. do a forum search on this subject.
Bill

62vetteman

Here is a pictorial by DZAuto ( Tom Parsons ) that shows what is needed to be done to convert to a posi.

Steve59

Thanks for the replies, but I'm not changing the pumpkin or converting the open rear to a posi, I'm changing out the entire rear axle, drum to drum. Need to know what that entails.

narlee

If you are replacing the housing and pumpkin it is just basic wrenching, the worst problems you should have are rusty bolts. If you are replacing instead of rebuilding make sure you save the old units if they are correct for your car or know the value if you sell them.

AZDoug

The front spring mounting bolts to the frame may be a problem re rust.

I had to helicoil some of the holes in the frame mounting bracket after drilling out broken off bolts.

Doug

1COOL60

As everybody has stated it is just a matter of wrencing to replace the entire housing. You may want to consider removing the "pumpkin" to lighten the load.

As Doug stated you might run into rusted bolts. I believe, however, you can swap out the housing without dropping the front of the springs. You will need to slide it out one side and then slide in the new one. Your choice how you go about it.

Have fun!
160

DZAUTO

Are you just going to remove the axle housing from the leaf springs, or, are you also going to remove/replace the leaf springs?
AND, are you going to replace/install the rebound straps with new ones, or are the existing straps in good shape?
My response will depend on your answers.

Steve59

I plan on removing the axle housing from the springs. I don't believe that they (the springs) need any work. The rebound straps are in good condition. About two years ago, I replaced screws holding the plates on with CC rivets, which I guess I'll have to replace again with newer rivets.

So far:

1.Need to separate the axle housing from the springs
2.Disconnect the shocks.
3.Disconnect the brake lines
4.disconnect the hand brake lines.
5.remove and replace the rebound straps.
6.Possibly drop front or rear ends of the springs.
7.The rear struts (?) on the 59, do they need to be removed?
8.remove drive shaft
9.Remove and replace the rear brake assemblies ie. drums,shoes, cylinders, springs etc. (bearings are new and good)

anything else?

One other item, and I hope I'm asking it correctly, what keeps the axle/pinon housing (pumpkin) at the proper angle in relationship to the drive shaft?

rich5962

Until Tom wakes up I'll jump in.....

Answer to your last question......The flat brackets on the axle housing that fits over the top of the springs, along with the radius rods(59+ to prevent axle hop) keeps the axle angled properly.

I did what you want to do, two times on 3 different cars over the last 2 months.......a '56 complete swap of axle assy, and a spring swap from a '62 bare frame to a '61 with the body on. Technically 4 cars, but one time was on a '65 IRS.

See if I remember this right as this will be the closest to what you're attempting......
On the '56, we swapped springs, axle housing, pumpkin, and brakes. It had HD springs, big brakes, posi axle with Halibrand wheels. We were turning it back to stock with a complete axle housing and rear suspension change.

The only difference is the '56 has no radius rods like the '59+ so that removal step isn't here. (edit....I just remembered seeing the pics again that this '56 had radius rods, that the prior owner added, so we had to remove those too.)

We had the car raised a few feet on the 2-post lift, removed the wheels and axles from the housing. We needed to take out the Halibrand axles to lighten the load and pull the HD brake plates. So we had to use a slide hammer on a jig we made for the Halibrand hubs. We then removed the entire brake assy parts, e-brake cables from them, brake backing plates, rubber fluid line, driveshaft, etc. We removed the pumpkin from the housing. Now we had a empty and lighter axle housing with no brake plates in the way. We then removed the shocks, u-bolts, and removed the springs completely by removing the 4 bolts from the front spring perch then the rear shackles. The light axle housing was then held in place by the rebound straps.

We then removed the axle housing, jogging it through the rebound straps right/left, down and out. Empty rear suspension done.

Installation of the stock axle and associated suspension hardware was basically the reverse order of the removal process.

It sounds like your task is similar, so if you remove the pumpkin and axles and brake plates, you won't have to re-do your rebound straps. If you're going to keep the brake plates intact on each one then straps must go.

One last issue. If you're putting in a Posi housing, etc, I don't remember if the the rear wheel bearings on a non-Posi are different or not. I seem to recall they are..........whether or not it makes any difference if you're keeping axles intact.

Rich

Steve59

Thanks this is a great help.

I forgot about being able to remove the brake backing plate and forgot that what I called "rear struts" are called "radius rods".

Also, the info re the pumpkin angle was just a question I had had for awhile since I never knew how that was done.

As to the bearings, it's been awhile since I had the axle housing rebuilt. I believe it was off a 57 and now has a correctly dated 1959, 3.70 posi rear in it. At the time of rebuild, I followed Tom's many treatises regarding bearings and axle lengths. They were excellent and I tried to follow them to the letter. So I should be good to go there.

One more note. the reason I've asked this question is that I have a mechanic friend of mine who will be doing the work. (I'm too old to be schlepping these heavy parts around, I can handle the small stuff, plus he has the lift and tools). What we do is go over what will be done and I try to leave him with all of the proper parts and manuals so all he has to do is the "wrenching". It's worked well in the past for us. But occasionally we end up with surprises which I want to avoid here.

Roger Walling

It is a lot easier to cut the rear axle / spring "U" bolts with a power saw or cut off wheel and replace the "U" bolts and nuts with new ones.

Most spring shops will do that. It makes for a better installation with proper torque in the bolts. Most spring shops will make you up new ones by looking at the old ones.

DZAUTO

Drain the oil from the rearend (drain plug is on the bottom of the housing).
Remove the driveshaft.
Disconnect the brake lines from the wheel cylinders.
Remove the axles and the brake backing plates.
Disconnect the brake rubber hose.
Unbolt the radius rods from the axle housing.
UNBOLT the U-bolts from the housing (I swear, I DO NOT understand why anyone would want to cut off the original U-bolts unless they were total junk!).
Remove the center section from the axle housing.
Now slip the empty axle housing through the rebound straps and take it out from under the car.
If you plan to replace the rebound straps, NOW is the time to do it-----------------------NOT after you install the other axle housing.
Put it all back together in reverse order. Start by slipping in the empty axle housing after the new rebound straps are installed (if they are replaced).

As I have pointed out 8 bazillion times-----------------ALLLLLLLLLLLLLLLLLLLLLLL 58-62 axles and axle bearings are the same--------------------FOR EITHER A POSI OR NON POSI REAR, PERIOD!!!!!

emccomas

Just to be sure, the rear end HOUSING that you are putting in came out of a Corvette, correct.

1955 - 1957 passenger car rear end housings will fit, but the pinion angle is not correct. It CAN be adjusted by cutting the rear end spring brackets loose and re-welding them.

It is basic wrenching, nothing real complicated.

Keep us posted on your progress.

Steve59

Tom:

Thanks for that complete reply. When all is said and done here, I plan to print up this thread and talk it over with my mechanic.

This reply has got me a little worried. I bought the original complete rear years ago (about 1975) and was told and it was marked as a 57 Vette.
Is there anyway to confirm that it's a Vette axle housing with it out of the car? And if it isn't, how is the pinion angle measured if I need to cut the spring brackets?

DZAUTO

IF IT IS A 57 VETTE HOUSING---------------------YOU DO NOT WANT IT!!!!!!!!!!!!!
The brackets for the radius rods are NOT, repeat, NOT on the 56-58 housings! The first year for the radius rods (and attaching brackets) was 1959. Thus, only the 59-62 axle housings are a direct, 100% swap for your car.
Why not just remove your axle housing, clean it up (inside and out), paint it and put it all back together again.

And, to answer your question. The quickest way to distinguish a pass car housing from a Vette housing, is to look at the 4-hole flange (where the brake backing plate attaches) on the end of the axle housing. They are NOT in the same position as on a pass car axle housing.

These are not the best pictures for making a comparrison between a car and Vette axle housing, but it's all I have at the time.
Notice in the top picture the lower side of the 4-hole flange is parallel with the spring mounting pad------------THAT IS A PASS CAR HOUSING (55-57).
Notice in the second/third pictures that the position of the 4-hole flange is rotated from that of the pass car flange and the lower side of the flange is NOT parallel to the spring pad. This is a 60 Vette housing that I installed in my 56 Vette.

Steve59

[QUOTE=DZAUTO;1587031293]IF IT IS A 57 VETTE HOUSING---------------------YOU DO NOT WANT IT!!!!!!!!!!!!!
The brackets for the radius rods are NOT, repeat, NOT on the 56-58 housings! The first year for the radius rods (and attaching brackets) was 1959. Thus, only the 59-62 axle housings are a direct, 100% swap for your car.
Why not just remove your axle housing, clean it up (inside and out), paint it and put it all back together again.

And, to answer your question. The quickest way to distinguish a pass car housing from a Vette housing, is to look at the 4-hole flange (where the brake backing plate attaches) on the end of the axle housing. They are NOT in the same position as on a pass car axle housing.

These are not the best pictures for making a comparrison between a car and Vette axle housing, but it's all I have at the time.
Notice in the top picture the lower side of the 4-hole flange is parallel with the spring mounting pad------------THAT IS A PASS CAR HOUSING (55-57).
Notice in the second/third pictures that the position of the 4-hole flange is rotated from that of the pass car flange and the lower side of the flange is NOT parallel to the spring pad. This is a 60 Vette housing that I installed in my 56 Vette.




[/QUOT


Tom:

Once again this is great info. The pics are clear enough and I understand what you are describing. Tomorrow, I'll check out the housing, but I'm beginning to get a feeling that what I have won't fit my 59 as I had intended, without some modifications. I can have the radius rod brackets welded on but not too sure about changing the flange angle in relation to the spring mount. Is this how the drive shaft/pinion shaft angle is determined?

A little history on this "rear". Back in the 70's there was a guy around here who had parted out, he said, about 85 different C-1's. (plus apparently, some late 50's and 60's Chevy's of all kinds).
I would go there and buy parts one of which was this rear. It was cheep and I figured if I ever needed a spare, this would be a good alternative.

Fast forward to about two years ago, I now have the time, and money to do the rear. Since the one in the car works fine but is an open rear of unknown dates, I decided to take my spare rear and make it a numbers matching posi. So I would have two good rears and as it turned out, both are 3.70 rears. The irony of all this is that lots of stuff he said were Vette parts weren't (including an engine I got from him which apparently came from a 64 Chevelle). This rear was marked as a 57, and like I said, it may turn out to be one of the more truthful things he sold me, unfortunately.

DZAUTO

With everything you have explained so far, I REALLY, REALLY feel your best solution is to jack up the car, put jack stands under the frame ahead of the axle housing, pull the rear apart, clean and paint the parts and have a rearend center section built with the gear ratio (3.70 as you mentioned) and posi that suits your desire.
As I understand it, your car already has a 59 axle housing under it, so if you want a posi, all that needs to be done is to install a posi. Your NON-posi 3.70 can be converted to a posi.
A few years ago, I put together this article about converting a non-posi rear to a posi. To the novice, it probably seems complicated---------------------------but it is not.

http://www.chevytalk.org/fusionbb/sh...hp?tid/223912/

DZVette

Here is Tom's article in PDF format.
DZ

Steve59

Tom:

I currently do have a completely new, rebuilt center section 3.7 posi. That's what's in the rear that's not in the car (the one I've been describing as a "57" rear)

I think my situation maybe be slightly easier than you have indicated. I have basically two complete rears from unknown years (so far). What I do know is the one rear ("57" ?) has a new 3.70 posi in it and the other (59?) is a 3.7 open. What I may end up doing is pulling the open pumpkin (which is currently in the car) and replacing it with the posi pumpkin. That maybe the simplest way to do things. I'll have to go back and re-read your axle length articles. I've forgotten if the axles currently in the car (the non-posi pumpkin) are ok with a posi. I believe they are, but will have to re-read.