remanufactured Differential Gears

Geoff

A good point as far as clutch performance is concerned, and one that should certainly be considered.  Back in 1982 I bought a 1950 Pacemaker sedan, which had overdrive.  Now I'm not sure whether the clutch had been changed, or the overdrive had been retro-fitted, as it had the 9" clutch which all  Pacemakers without o/d had but after driving for several hours on the way home the pedal started going in towards the floor, and when stopped I could not get  into gear.   The corks were obviously swelling up, due to the clutch slipping.   Cut a long story short,  I later fitted  a 10" clutch and no further problems.   The old analogy of pedaling a bike in high gear  into a head wind - you have to push harder.

bob ward

I don't know the story behind this but to me the pinion splines on the Colorado Springs CWP were over length, they were cut unnecessarily long. Possibly something that could be adjusted rather than making a direct copy of what exists. 

Jon B

Geoff, here is an off-topic question:  In 1980 I was cruising along on a parkway in my 1937 T with overdrive fitted, and suddenly there was a "chunk" from somewhere in the rear of the car.  The motor sped up, and I suddenly realized that no matter how hard I pushed the accelerator, the car slowed down until it stopped.  Something was slipping.  I ultimately found that the rearend was bad, and left the car at a nearby garage.  The mechanic removed the guts from the rearend and I transported them -- along with a NOS ring and pinion gear -- to Nelson Creasy, who put everything together, ready to put back into the axle housing.  Then I picked up the finished product from Nelson and transported it to the garage where the mechanic installed it in my Terraplane's axle housing.

What I failed to do, was ask anyone what had happened?  I still don't know what broke, to this day.  I assumed it was something in the pumpkin.  But now it sounds like maybe i had a six bolt ring gear (crown wheel) and maybe the bolts broke off.

From my description of what happened, can one diagnose what might have gone wrong?  Or could it have been one of several things?

Jon B

Jared, I agree that the project should move forward without delay, but the March 15 deadline won't make the next WTN.  No sure when the next one comes out, but someone should definitely alert Sam Jackson to put something in the magazine about the gear project, in the next issue.

Geoff

Jon B said:

Geoff, here is an off-topic question:  In 1980 I was cruising along on a parkway in my 1937 T with overdrive fitted, and suddenly there was a "chunk" from somewhere in the rear of the car.  The motor sped up, and I suddenly realized that no matter how hard I pushed the accelerator, the car slowed down until it stopped.  Something was slipping.  I ultimately found that the rearend was bad, and left the car at a nearby garage.  The mechanic removed the guts from the rearend and I transported them -- along with a NOS ring and pinion gear -- to Nelson Creasy, who put everything together, ready to put back into the axle housing.  Then I picked up the finished product from Nelson and transported it to the garage where the mechanic installed it in my Terraplane's axle housing.

What I failed to do, was ask anyone what had happened?  I still don't know what broke, to this day.  I assumed it was something in the pumpkin.  But now it sounds like maybe i had a six bolt ring gear (crown wheel) and maybe the bolts broke off.

From my description of what happened, can one diagnose what might have gone wrong?  Or could it have been one of several things?

Would definitely be the bolts sheared.  

hasktavern1

Bob, re; your observation about the pinion splines of the former run, the CNC should be able to double check that....I'll make sure to discuss it with Tom.  Jon, I will reach out to Sam, but the next deadline is 4/1 for the May/June issue, so it will print well past this initial organizing period.  I have reached out by email to all the regional chairs; International chairs; and the Railton club; and HET Facebook.  I also looked online at some of the AACA car clubs and found several that had organized differential gear production, and generally, even after a period of months, they had a hard time getting very many customers.  Timing, cost, and other solutions are the reasons that we may also not get a lot of takers, even with a 6 month window  (That's my somewhat researched opinion and I hope I'm wrong).

Jon B

Two quick thoughts on 'spreading the word'.

1. I have access to a list of all the H-E-T chapter editors.  I can send it to you, or I would be happy to do a mass e-mailing to them, if you could prepare a short article I could send them for their newsletters.  In this way you can reach at least a portion of H-E-T members via their local newsletters, even if you cannot reach them through the WTN.

2. Be sure to place an announcement in the AACA online forum, under "Hudson".  Although it's not an active Hudson forum, you might still pick up a couple of orders from people who follow it.

It might not be a bad idea to send a short article to the WTN anyway, even if it will be published past your deadline.  If for some reason the project were to be delayed, the announcement would, then, reach H-E-T members in time.

Jon B

Geoff, thanks!  I had always thought that my 1980 catastrophic failure was either due to wear on some bronze bushing or spacer within the pumpkin, or to the one cog of the ring gear which had broken and had been welded back, by a past owner of the car.

Would it be true that the innards of a standard rear end from (let's say) a '46-7 Hudson can be easily transplanted to a 1937 axle housing? In that case it might be a good precaution to take, due to the 8-bolt setup of the postwar cars resulting in the lessened chance of shearing of the bolts.  (And of course one could then install the new repro high-speed gears as well, assuming that one purchased the 8-bolt version.)  

I'm thinking that anyone currently with a 6-bolt rearend, would want to consider switching to an 8-bolt version before ordering the new gears.  Otherwise you run the risk of having the new, high-speed 6-bolt ring gear shearing off at some point, possibly damaging that $1300 gear!

Jon B

Send an e-mail to the Nicola Bulgari collection in Allentown.  They have at least one Hudson (Park Waldrop's magnificent '36 Hudson Eight convertible) and Mr. Bulgari LOVES to drive his cars, not just show them.  He might be in the market for a high-speed gear set or two, unless of course Park installed one before selling the car. (Park just told me the car does not have the 3.59 gears)

hasktavern1

Jon, yes please send the email addresses of the editors and I can send the project information to them.  Send the addresses to: terrahasktavern@netsync.net (drop the 'terra' before sending).  I will also look up the email address for the Bulgari collection and send info to them;  and will post on the Hudson portion of AACA.  I also emailed Sam this morning for his feedback on WTN print timing.  Tom is also doing some 'phone networking' and is getting the word out and building some interest that way.  If anyone reading this has any other networking ideas please let us know.

Geoff

Further to the problem of bolts shearing off, I don't know the  quality of the bolts that were originally fitted.   Apparently the problem started showing up after a few years, which is why they shifted to the stronger construction in 1939 models.  The only one I have seen with broken bolts, the original bolts had no markings on the heads.  Grade 8 bolts, with  a plain shank going through the  carrier should be used, and torqued up to 45 lbs.  Personally I would also put some arc weld around the periphery as well.  This can always be ground off if you have to  replace anything at a later date.  

Jon B

So if one is installing a new ring gear (er, "crown wheel"), and if it has but 6 bolt holes, you are suggesting drilling a few more holes around the perimeter of the ring gear?  Then drill mating holes through the differential, and weld bolts (or studs?) to the differential, which will engage the crown wheel?  Not sure I understand. 

bob ward

A 6 bolt CWP installed properly, especially now that loctite is available, will give many years of trouble free service, there is absolutely no question of that. Use plain shank grade 8 bolts with loctite, put loctite between the carrier and the CW. 

As Geoff says the problems started to show up in the 6 bolt diffs after a few years and that is why the redesigned 8 bolt diff was introduced. 

I have read, I can't remember the source, that the main cause of failure was initiated by the bolt lock tabs. Bolt lock tabs are of course made of soft steel so the the tabs can be bent up against the bolt head.

The CW to carrier bolts were torqued down through the soft steel lock tabs and over time the lock tabs compressed/fretted a little, a little of the bolt torque was lost, the lock tabs became more worn and the downwards spiral continued to its inevitable conclusion. 

Plain shank grade 8 bolts and the marvels of loctite will eliminate the problems.

Jon B

For what it's worth, regarding the shift to 8-hole crownwheels in the 1939 model year, the following comes from the Hudson shop manual for 1939 (section 13, page 11, issued August, 1939.)

In this design (the 8-bolt drive gear) the bolts have a larger diameter and notched shakeproof washers are used under the gear bolt heads in place of the soft steel lock plates....  Due to the change in number of bolt holes from six to eight and an increase in the pinion shaft diameter at the rear end, these parts are not interchangeable with those of former models.  The service operations, however, remain virtually unchanged as the parts are of the same general design.

Note: in making repairs to former models where the soft steel lock plates were used under the gear bolt head it is recommended that shakeproof lockwashers be used instead of the lock plates.  This latter arrangement provides a more secure lock and will prevent the bolts from loosening.

Due to increase in the size of the pinion shaft and revisions in the differential carrier, the roller bearings are not interchangeable with those formerly used...  Inasmuch as the number of drive gear bolt holes has been increased and the size of the differential bearings has been increased, the 1939 differential case is not interchangeable with that of previous models.  The service operations on these parts, however, do not change.

Geoff

Jon B said:

So if one is installing a new ring gear (er, "crown wheel"), and if it has but 6 bolt holes, you are suggesting drilling a few more holes around the perimeter of the ring gear?  Then drill mating holes through the differential, and weld bolts (or studs?) to the differential, which will engage the crown wheel?  Not sure I understand. 

I never said that Jon, sorry.  You cannot just drill new holes, the parts are not compatible, and besides you cannot drill and tap hardened steel.

hasktavern1

Excellent ideas and information in the above exchange.  As a do-it-yourselfer, it's very useful.

hasktavern1

To add a little to the technical info, tho most of you probably know this:  Brandon Wright, who's restoring a 37 coupe, posted the following on Facebook:

From Brandon: "Wanted to add some references for some who may have some doubts on the gear ratio that is being made.

The 3.55 gear was actually a ratio that was an optional gear set offered by Hudson. Along with a 3.88, a 4.55, and a 5.12. The standard gear being 4.11.

Generally these steps cover a comfortable 5mph "cruising" speed change for the same rpm speed. Say if with a 4.11 comfortable speed would be 50-55, with a 3.88 it becomes 55-60 and with a 3.55 60-65. Nice thing with Hudson engines is they are designed for a decent torque curve and built more for higher rpm then usual engine designs of the era. This was especially true in the late twenties and early thirties, which is "one" of the reasons why Hudson employed unusually low gear ratios in their cars.

In addition with higher comfortable speeds being achievable, you do need to consider the condition of your steering, brakes, chassis, and overall driveline. With the wear and neglect these cars have seen over 70-80 plus years. There is generally allot to fix to make them properly "higher" speed worthy again.

(Picture included is from page in the 1937 Hudson parts book)"

hasktavern1

Also written by Brandon on Facebook:  "first of all thank you for bringing this information to our Facebook forum. Not to mention the cost is very reasonable for a set of ring and pinion gear which are very difficult to cut. For reference I had one new timing gear cut for my 8 cylinder Hudson which cost 1200. alone and that was just a bevel cut gear.  I'll definitely reach out for an order."

hasktavern1

More from Brandon Wright on Facebook:  He apparently was determined to not have to take things completely apart and has figured out a way to tell if you have a 6 or 8 bolt rear, by shining a light into the drain hole.  Normally this wouldn't be something we would be needing to do, but with all of our talk about 6 vs. 8 bolt gears and which replacement set to order it has become a thing   :  

Brandon's method:  "First for reference is a quick look at what we are going to be looking for. The six bolts that physically hold the gear to the carrier. Notice the spacing between the bolts. Keep this in mind for the next few pictures."

"Jack the car up and set the rear axle on stands, put the transmission in neutral. Pull the fill plug out. Use a paint marker and mark a spot on the carrier that is close to one of the bolts you will see in the next picture."

"Look closely at the arrow, that is one of the ring gear bolts. You can rotate your gear and count these as you go until your mark shows up. If you have an 8 bolt you will find the spacing to be really close together compared to a 6 bolt."

dantheman

Hi Tom, I'd be interested in the gears for my 36 T also.     Dan

Rocket

Hi Dan if you are seriously interested than let hasktavern know so you can get on the list if we have enough people who realy want these we will get them done I am having a set of Ivans gears and a 6&8 bolt carrers sent to the gear company now so they have everything they need as soon as we tell them to start making them. THE DEAD LINE IS MARCH 15TH 2021 if we do not get enough people we will just close this thread (JUST SO YOU KNOW ALL WE NEED IS A TOTAL OF 15 SETS ALL TOGETHER  IT DOSE NOT MATER IF THEY ARE 6 BOLT OR 8 BOLT)

Park_W

Re contacting Mr. Bulgari, you want to contact Keith Flickinger, who's in charge of maintaining the collection.  Good guy.

hasktavern1

Thanks Park,  That's the one suggested contact I haven't made as the organization is not as reachable as some.  Do you or someone else on here know how to reach Keith directly?

hasktavern1

Project update:  we are slowly but surely building a list of customers for these gearsets.  Don't be shy and don't miss out, even if differential gears aren't on your current to-do list!  As Geoff reminds us in his Technical Topics, essential parts seem never to be available when they are essential, and vice versa.  These gearsets will hold their value and will be marketable, even if for some reason you end up not using them.   In the meantime, we are working hard to gather all the correct parts/prototypes to ensure that all remanufactured parts will fit precisely.  Tom has some in hand already, but we will know this coming week, if we need additional parts for models.  Please watch this thread, as there may be a call for additional help with this aspect of the project - or reach out now with what you have to offer.  Thanks to all of you who have weighed in and helped so far!  

Park_W

I've found his phone number. email me and I can give it to you. ( address is in HET Roster)

hasktavern1

Thanks Park....will do

7XPacemaker

I would love to have 3:55 gears in my '39 112 but am concerned about how hard the 175 would have to grunt to get the car moving from a stop!

Park_W

For the folks who are going to run these gears in an overdrive car, here's a recommendation.  With those gears, you're going to have more situations where you're in OD with speed down to 30 t0 40 mph, and you want to accelerate.  You'll want to get out of OD, but sure don't want to floorboard the accelerator to do that.  Yes, you can put a switch on the dash to cut out the governor, but there are enough switches on the dash, and you'd rather not have to take your attention away to reach for that switch.  Here's a well-proven (by me) solution: Move the OD kickdown switch over to the left side of the steering column, and use your left foot to do the kickdown.  Place it where it wouldn't interfere with the dimmer switch and is comfortably reached with your left foot.  Aside for making the holes for the switch and two screws, you just need to lengthen the four wires that are on the kickdown switch.  I did this on my OD Hudsons, and a few for others. It's a good move.

hudsonsplasher1

In replacing the gears in my 37 Terraplane, is it a good idea to replace the bearings also? If I would need bearing, where do I start looking.

bob ward

Your call, but for me I would go for new bearings. Assuming you are having a pro set up the new gears in your pumpkin, he/she will know where to source them.