: Differential breakdown

04-03-11, 03:05 PM
Hello guys,

A week ago I had a bad experience with my caddy. Steering and brakes wearing elements changed, ignition tuned, carb cleaned, new ventilator clutch and bands... Everything seemed to go perfect but 20 kms before the car arrived home something went wrong: Transmission began to seem retained progressively and then even making a snoring noise and finally like metal were rubbing against metal as I was looking a safe place to stop. When I got out I saw smoke out of the link between transmission rod and differential. I called the tow to take the car to its housing. The car still moves but the rear axle is braking.

Before it happened I could hear a slight howling noise from transmission. The mechanic told me that it came from a worn rack and pinion but nothing important; just an unpleasant noise. Now heīll have to open differential and locate problem.

Iīd like to know your opinion or similar experiences.


04-03-11, 05:33 PM
Maybe you ran out of gear lube? I'm not quite following your story, of where the problem was noticed, did you ever have a bad pinion leak? I did on my Calais, and I couldn't get the fill plug open, so I couldn't do anything. I figured as long as it was leaking, there was still lube. Finally, something went wrong and it wouldn't really move in either direction, I thought the rear end blew. It turned out to be transmission. If you just had the trans worked on, maybe this is the problem. One way to rule out the axle I suppose would be to disconnect the driveshaft and see if you can turn the pinion. It should turn by hand. You can check the rear U-joint at this time too, to see if it's binding.

04-04-11, 04:59 PM
Of the many things we had to do, one should have been checking gear lube level. Thatīs one of the possible causes Iīm thinking of. The mechanic thought (before checking it) that could be a ball bearing or a gear out of its place.

Smoke out of differential makes me think thatīs the problem source. When the tow platform tilted to unload the car, it did not fall in neutral so I had to turn on engine and help it with reverse geared. Anyway, the test you propose is very simple and useful to be sure that itīs a rear end -and not transmission- problem. Anyway, weīll take the opportunity to check thoroughly the differential.

04-06-11, 06:54 PM
Today the mechanic has checked whatīs the problem: No lube at all :helpless: and progressive wear of gears until differential has failed. Gears were stained in orange as an evidence of overheating probably when breakdown happened. Rack teeth were even sharpened by abnormal friction.

The screw top was not the original one and opening it was difficult. Maybe thatīs the cause of negligent maintenance. Probably, differential lost oil through front pinion seal until the problem solved by itself as oil was over:rant2:

Now Iīll have to look for a new differential. If anyone knows where can I find one in good condition that can be shipped to Spain, Iīll be grateful. (If possible with a long gear ratio)

04-06-11, 07:15 PM
What a pain! As I said, I thought I had this problem, I know the sick feeling. Good luck finding one. I've hoped to find a limited slip myself, but that's about how far it went, hope...

04-06-11, 07:31 PM
That's a sad story. Around here all those fluids get checked during routine oil changes. I just decided this year that I'm not going to restore my '70 Deville so I have a rear axle that i will be selling soon but i have no idea about shipping it to Spain. I may look into it for the fun of it. I'll post back or PM you if it looks feasible.

04-07-11, 09:59 AM
Your housing should still be good. You will need a new gearset, possibly a carrier ( if the centerpin hasn't worn excessively ), new bearings and seals, and possibly new axles. Save you the expense of shipping a heavy and bulky housing.

04-07-11, 07:07 PM
Good thinking deville33, I knew there had to be a better solution.

04-07-11, 08:01 PM
Of course, I do not need all the rear axle / housing; just the carrier. New seals and gasket can be bought new, even bearings.

Iīve been told that it could weight about 55 lbs. Maybe you are not interested in selling just the carrier but all the rear axle as you should have to take it out from the housing. Am I wrong, cadillac_al?

It can be sent by U.S.P.S. but shipping cost would be more than $250. Itīs unavoidable as itīs a heavy part. Iīll have to pay it, whoever sells it to me; Itīs very unlikely finding it in Spain.

BTW, Iīm looking for a '70 caddy steering wheel. Mine operated by a button far away from driverīs hand :helpless: (as original horn operated by wheel rim failed as almost all 69s). Are you thinking of selling it?

04-07-11, 08:24 PM
What a pain! As I said, I thought I had this problem, I know the sick feeling. Good luck finding one. I've hoped to find a limited slip myself, but that's about how far it went, hope...

You got it right. Actually I was reluctant to think that, as I could not think that previous owner was such a fool to allow that happened.:nono: but, as the mechanic told me, the differential was sentenced to death. Filling the diff with lube 2 months ago would have given it just a few more months of life. I have to get another one, one way or another.

04-08-11, 09:15 AM
BTW, Iīm looking for a '70 caddy steering wheel. Mine operated by a button far away from driverīs hand :helpless: (as original horn operated by wheel rim failed as almost all 69s). Are you thinking of selling it?

Usually It is not the horn switch ( in the center of the wheel ) that fails, but the relay. I have bought cars with a button as you describe. only to find that it only needs a new relay or horn. If your wiring still running to the horn center, you can check the circuit with a test light.

04-08-11, 10:36 AM
Horns do work, by pressing the right button you can see under dash. The problem is that the wheel rim you pressed to play horn originally is shattered, as you can see in the pic below. I donīt think it works :bigroll:

http://s4.postimage.org/riqzf20u3/IMG_0735.jpg (http://postimage.org/image/2phfeehgk/full/)
free image host (http://www.postimage.org/)

04-09-11, 09:39 AM
I think those wheels' had the horn activation on the outer ring, different than conventional configurations. I think there was someone who repaired those, but you would have to go way back in the achives, posts from 5 years ago.

04-09-11, 10:31 AM
I've been looking into the rear axle compatibility and it looks like they changed the rear axle in '70. I was supposed to go to the junkyard today and I was going to check the Hollander book but it looks like it will be next week now. Still too much snow around here to walk the junkyard.

04-09-11, 12:37 PM
If this illustration is right your '70 rear axle is like this:
http://s3.postimage.org/buplj2w2n/Group_5_7.jpg (http://www.postimage.org/)
post image (http://www.postimage.org/)
I have no illustrations of the '69 but my differential carrier is similar to this one (taken from a 59-60 limousine):
http://s1.postimage.org/8mxp9z7jk/Bj34g_Lw_BGk_KGr_Hq_YH_Cg_Es9_ZZVs_QRBLVM0w_L0_Vw_ 12.jpg (http://www.postimage.org/)
post image wordpress (http://www.postimage.org/)

Thatīs just what I need but I have to be sure if itīs compatible with '69 transmission.:hmm:

Tomorrow Iīll go where my car is. Iīll try to take some photos of the diff.

04-09-11, 10:53 PM
OK that's the difference then, mine is like the picture. Yours will be easier to work on in my opinion

04-10-11, 11:32 AM
I gotta admit, I'd love to see pics of whats left of the dif.

04-11-11, 12:27 PM
Definitely, 69 and 70 are different, and mine is easier to change and to work on, as the mechanic said: Just disconnecting transmission bar, taking out differential carrier with gear set after unscrewing it and getting in the new one, connecting trans. bar again, just adding new seals and gaskets. If necessary, new bearings are available.

Yesterday I was working on other issues of my caddy and took some pics of the diff.:

http://s1.postimage.org/9auz1hpuo/IMG_0863.jpg (http://postimage.org/image/27n3lvk1w/full/)

http://s1.postimage.org/9av403rca/IMG_0860.jpg (http://postimage.org/image/27n8khlj8/full/)

http://s1.postimage.org/ukiv9k94k/IMG_0858.jpg (http://postimage.org/image/27ndj3n0k/full/)

http://s1.postimage.org/5r9jilgit/IMG_0857.jpg (http://postimage.org/image/27nlssdhg/full/)

image upload (http://www.postimage.org/)

04-11-11, 12:40 PM
I gotta admit, I'd love to see pics of whats left of the dif.

By now, we did not open the diff. The mechanic could see the gear set by a microcamera at the end of a thin hose, introduced by the filling hole (something similar to those used in surgery) so he saved previous work.

When I get the new one Iīll take some pics of the remainings of the original one. Itīs incredible that it run at least more than 1.000 miles (maybe much more) with no lube at all.:hmm: Iīve heard about cases of differentials totally blocked when they had enough or at least some lub.

05-23-11, 07:36 AM
Hello guys,

last friday I received a "new" differential for my 69 SDV. After contacting several companies, I found AA National Auto Parts, in Phoenix, specialized in used cadillac parts. As they have some 69s, they helped down a differential in good condition and sent it to me by air through a local company that crated it thoroughly. They looked for the cheapest way to send it from AZ to Madrid, so finally I paid $ 200 for the part and $ 640 for the crating & transport (just the diff. weighs 95 lbs.!). Itīs the best quote I got. Iīve also bought a new diff. carrier gasket and waiting for a new diff. pinion seal. We hope the rest is in good condition.

As soon as I receive the seal Iīll contact the mechanic to change diff. Here are some pics I took last saturday of the diff as I just opened the crate. I havenīt a great experience in differentials, but for the info I checked on Internet this seems to be Ok. Waiting for the mechanic opinion:

http://s4.postimage.org/cg2t7mdva/IMG_0924.jpg (http://postimage.org/image/1t90275es/full/)

http://s4.postimage.org/fzoskyt2u/IMG_0923.jpg (http://postimage.org/image/1t91pqhwk/full/)

http://s4.postimage.org/jjaryb8ae/IMG_0922.jpg (http://postimage.org/image/1t93d9uec/full/)

http://s4.postimage.org/jjatluks6/IMG_0921.jpg (http://postimage.org/image/1t950t6w4/full/)

http://s4.postimage.org/n2wsz6zzq/IMG_0920.jpg (http://postimage.org/image/1t96ocjdw/full/)

http://s4.postimage.org/qmiscjf7a/IMG_0919.jpg (http://postimage.org/image/1t98bvvvo/full/)

http://s4.postimage.org/u64rpvueu/IMG_0918.jpg (http://postimage.org/image/1t99zf8dg/full/)

post image wordpress (http://www.postimage.org/)

More pics when we change differentials ;)

05-25-11, 08:47 PM
I took the diff. to the mechanic as he asked. Heīll start by changing pinion seal to the new differential. Heīll probably need some equipment difficult to take where the caddy is. This way, changing the part will be easier. I canīt wait to have my car in the road again