Who is capable of rebuilding a 37 LaSalle differential assembly. I know this has been kicked around in the past and I have reviewed old posts but can't seem to come up with anything. Terrill machine says no and was not able to offer any suggestions. Thanks much, Scott Kennedy
There is no answer I'm afraid. There aren't even any specifications or manuals for it as Cadillac deemed it a replaceable unit. Easier to find a used replacement because they were a very strong unit. 60 series Cadillac will fit and be a little higher ratio.
Like Steve says....
The smaller series had hypoid diffs. The larger series had spiral/bevel and they were rubbish. Fortunately, '37 was the last year for them. Don't get caught with the spiral bevel...
I'm concerned that if I install another unit, it may not be any better than my present one. My present one is not all that bad. But it does have a noticeable whine and a slight growl sometimes at slow speed. It appears that the major issue regarding rebuilding these units is that the ring gear is riveted to the planetary gear carrier. This makes complete disassembly and inspection of the planetary gears impossible without drilling out the rivets. It would seem that the rivets could be drilled out and then be replaced with grade 8 bolts with an adequate shoulder length, castellated nut and cotter pin. has anybody tried/done this?
Maybe I'm way off base and missing something very basic.
The point is Scott there are no parts available. Cadillac made that situation deliberately. If you found a replacement diff, you can always examine it first?
I guess it was the beginning of the disposable era. Thanks Steve and John.
Odd this is that Buick adopted this design late 50 and early 60s and they did print manuals with some specs on it but that doesn't help us with the spares side of things. The diff also requires a series of special tools and I have been 20 years trying to find them all. I have acquired just one so far. The most important one would have to be made should I ever have to get into it, once again though, no good for getting parts. When I bought my car I took the step of getting another diff just in case.
If your 'growl' is only at low speeds it could be the transmission as diff noises usually only change due to 'power on, or 'power off'
Apparently in that era and into the '50s Cadillac made differentials to be replaced, not repaired. This is certainly true of '49 Cads, as it says in the shop manual it can only be taken apart successfully at the factory. A mechanic friend of mine once doubted this and attempted to take apart a diff belonging to a friend. He found that certain parts (I can't remember exactly what) were "pinned" together in such a way that they would be impossible to put back together.
My own experience with my '49 is that the diff in the car when I bought it 34 years ago had a chronic pinion seal leak. (It couldn't be fixed because the surface on which the seal rides was pitted, which would damage a newly installed seal.) I replaced it with another diff from a junk yard, which didn't leak but which had an audible hum at all speeds. Also, it was the wrong ratio, 3.36, whereas my car with a manual transmission needs a 3.77. After 20 years or so it still worked perfectly except for the hum (and wrong ratio). Finally, I found a 3rd diff at Hershey with the correct ratio which doesn't hum or leak and which is now in the car.
The point is, and I've heard this from other guys too, is that a Cadillac diff can hum for years without any other ill effects.
Yes Jay, your mechanic friend is right. Some of the parts are either riveted or pinned, with the pins being in blind holes. No way to extract them without drilling them out.
I will try and reduce the slack between the ring and pinion down to .005(+/-). That might reduce the hum but if not, I will live with it. Appearance wise there are no obvious signs of wear. There are signs however, that others have been there before me. To what end, who knows. I'm ok with the 3.91 ratio since I have installed a Gear Vendors overdrive which incidentally, has a slight sound of it's own when disengaged.
I am grooming this car for the 2020 Rally New Zealand. Assuming my wife and I survive this ordeal with our marriage still intact we are eying the Peking to Paris Motor Challenge. As you can guess, I am paranoid about anything that is difficult to repair by the side of the road.
There is no adjustment between the crown wheel and pinion unless you have the specific tools to do it and that consists of a really special one that parts the two towers that support the crown wheel unit and allows you to increase or remove the shims to change the backlash. These towers are cast iron and I have seen other attempts to part them snap them clean off!
I understand your point Steve. This will take some fixturing. Definitely not a slam bang hammer and chisel job such as was suggested on another forum.
If you are in N. Zealand, I now understand why you don't just replace the diff as we here in the US would.
As Steve and others have pointed out, the only repairs that can be made are to replace the pinion bearing and the pinion seal.
If you are "eyeing" the Peking to Paris rally, I would speak to some of those who have done it before. A team did it a few years ago in a '49 Cadillac, and I remember from reading the daily report they posted online that they had to make one or more repairs of some kind on the side of the road. Maybe there is some way you could get in touch with them. It's probably not for the faint of heart, since between China and Europe conditions were not good in some of the countries they passed through.
Another way, if you are not worrying about originality is to simply graft a different centre to replace yours, and if necessary, re-spline the axles.
Bruce. >:D