Bad sound coming from rear end

The weather here in New Jersey is getting cooler I decided to fire up the car   and go for a drive, but didn't get too far. I felt and heard a clunking sound and vibration, not sure where it was coming from, did some troubleshooting, jacked up one side of the rear end and rotated the tire. it would bind and lock up with only a little turn then raise both rear tires and it rotated ok looks like something is binding in the diff. I will be removing it from the car to see what went wrong. Looked thru the assy book to see what  could be the problem, it looks pretty straight forward. Maybe a bad gear. I will post the findings. Has anyone had this problem ?

Hi! Could be a broken tooth on one of the pinions.....?!!
Greg

Dean need your help on getting these parts. Just took the rear end out of the car and found the problem. all the gears are chipped or broken teeth. have to order parts from Dean
parts needed.
LK0307   2
LK0308   4
LK0304   1
LK0311  4
Don't know why  the teeth broke the tooth got into the rest of the gears and broke them. The spur gears on the axle are also broken The case is OK

Popping wheelies and laying down the rubber!! https://2img.net/i/fa/i/smiles/lol.gif

Looking at your parts, I would guess a chipped tooth first, then another bigger chip (long one) that jammed itself and broke the other gear in two. Wouldn't take much to start a chain reaction. At least you can say you have driven your steam car long enough to have to rebuild its differential. For which is an enviable place to be.
Grier

trying to get it done for the trip to florida for the winter.

Hi Jim, I was right! But Grier's blow by blow diagnosis I think is absolutely correct. However, I do feel very sorry for you having to rebuild - always a pain, but at least you have been in the enviable position of actually driving your Lyka (for some years now)! I can't even imagine if that day will ever come for me!!
Kindest regards
Greg

I've been in contact via email with Dean, This was a Modelworks kit which may present a problem with STW, Dean is checking on it now, There may be a difference between the two designs for series one from both companies , I hoping this is not the case.

Dean did respond at this time and said that this car was made by Modelworks and not from STW which could mean that the gears from STW may not work if they were not machined to the same specs. He is checking further to see if there is any difference. If there is any difference  will the new gears fit into the case. I'm still waiting for him to get back to me. If things go well all will work, but if not I will have to made a new set of gears and will need the data for cutting them which is another problem.

jjtjr wrote:Dean did respond at this time and said that this car was made by Modelworks and not from STW which could mean that the gears from STW may not work if they were not machined to the same specs. He is checking further to see if there is any difference. If there is any difference  will the new gears fit into the case. I'm still waiting for him to get back to me. If things go well all will work, but if not I will have to made a new set of gears and will need the data for cutting them which is another problem.

Is it possible that a skilled machinist could measure the gears that you have, and make new ones to the same dimensions ? Just a thought..

At this point I'm waiting to hear back from Dean, it should be monday or tuesday.  If he has them my problems are solved. If not I could cut them myself. I have cut gears before. It's just a a long process not having a CNC  bridgeport milling machine and Lathe,  mine is a old bridgeport  with a DRO and Lathe with DRO. Then the gears have to be heat treated to a HRC  between 50 to 60. It would be great if he had the calculations on the gears. This would make cutting them faster.  Four pinion and two axles gears have to be cut. The plan would be to cut teeth in  a long piece of stock then part each gear, this would make things a little faster. I have  been checking around on machine shops that can cut gears not all do.
My question is why did the gear fail in the first place,  yes a tooth broke off then cause the other gears to fail. Was it a design problem or just material failure. This would help when making a new part, because i don't want to reproduce a part which will fail again. where not talking about a high HP engine in our cars, like our daily drives.

I've been collecting data on modern spur gears. This is what data on gears I have so far. Having the specs on the old gears could may be explain why the old gears failed.

type of steel = s45c
pressure angle  is 20 degs
number of teeth = old gears
specs on gears = old gears
there is a lot more calculations needed for cutting gears which I could measure from the old ones.
The problem with cutting gears is you can't have  39 perfect teeth  and 1 not so perfect.

Hi Jim, Looking at your pictures of the broken spurs, it seems to me that the quality of the original metal was very poor? It seems to be very crystalline? Not cast surely? Or worse, cast from some sort of 'muck' metal??!!
Regards
Greg

Hi Greg, That's what I was thinking also. Having the old gears I could do a HRC test and see what number it was.Taking a closer inspection of the gears you can see wear where it make contact with the axle gears. If you look at the photos , in the very middle of each pinion gear you can see what I'm talking about.This should not be present do to the little use it gets, this presents other questions with the material and harding.

The good news is that Dean has the gears that will fit and will be sending to me. as soon as we work out the shipping to the USA.

Here is the latest findings on the gears.. Did  a Rockwell test on the gears. The small ones are 40 HRC and the large ones are 48 HRC from what info I gathered on pinion gears they should be between 50 to 60 HRC. I am getting a new set from STW to get the car back on the road But at the same time I order 4140 bar stock and will be making new gears.  4140 can be case harden to any HRC number,  it will  be between 50 to 60.

Just received the gears this morning did a HRC test both gears are 63. Now time to assy diff and test drive. Thanks to Dean ready for the road again

Good to hear. Good luck with the assembly. Hope to see you steaming soon.

Here is the latest findings on the diff.
I wanted to know why the gears broke in the diff and a very close study was made not just assy the diff, and this is what I found. I assy. the large gears on the axles and check for end play.   The end play can not be removed due to the axles that were a replacement from Modelworks many years ago  The shims do not affect the end play in the axles. I shot a video to better explain the problem. Still thinking on how to resolve this end play. I may turn the wheel side of the axle as talked about in the video. What looks like had happened is the end play caused the axle gear to move into both pinion gears rotating clockwise and counterclockwise and broke the teeth off. This is something other owners should check. It is not obvious if you are not looking for end play. The big question on the fix ? I can turn the wheel side of the axle so the bearing will seat further on the axle.

Jim I have also noticed that the gear blanks only have a small radius on the tooth edge. Because I believe that the two halves or opposing axles will no doubt flex in this design, for an added protection against this flexure against counter rotating gears in the differential, I would chamfer the gear profile from the outer gear diameter to the root diameter. The image I attached shows what I am trying to say. I do believe that you have discovered your issue with the end play. Correcting that will solve your problem.
Regards,
Grier

you tube on the axle

Grier wrote:Jim I have also noticed that the gear blanks only have a small radius on the tooth edge. Because I believe that the two halves or opposing axles will no doubt flex in this design, for an added protection against this flexure against counter rotating gears in the differential, I would chamfer the gear profile from the outer gear diameter to the root diameter. The image I attached shows what I am trying to say. I do believe that you have discovered your issue with the end play. Correcting that will solve your problem.
Regards,
Grier

Since I had the axles out of the car I machined a radius on the teeth of the gear only on one side the side that engages with the pinion gear. Thanks for the input.

When treading the nut on the end of the axle in the diff the two axles made contact and you couldn't tighten them all the way tight so what is being done is new nuts were ordered from amazon they are m16 by 2.0. These are jam nuts which are thinner then normal nuts. Then these nuts were thinned on the lathe and tooth lock washers were used instead of the spilt washers because they are thinner , all this is done because of the space between the two axles shafts in the diff. also since the nuts are thinner I was able to remove more thread from the axles on the diff side.

Latest video

Happy to report that the diff is now back in the car. All went well, the space between the two axles is .034". The gearing is a little tight but will work in after some driving. Working on the rear brake lines I noticed the chain was hitting the brake line that went to the right wheel. The   distance between the fitting and chain is very close and if the chain has too much play it will hit the copper line. Working on a fix.

The right wheel brake line was in  position that was very close the the chain and could be hit if the chain got loose and so it did. The copper tubing had to be bent with  such a tight radius   to clear the chain and could easy be kinked.  My solulation was to make a 90 deg fitting to  clear the chain. They  have a bubble flare on that end.This is what I did, cut off the copper tubing  just pass the bubble nut fitting with a little copper sticking out of it, then got a 90 deg. flare to pipe brass fitting for that size tubing cut off the pipe threads so the fitting got smaller drilled out the end of the fitting so I was able to insert the copper tubing into it, then silver solder the tubing into the 90 deg. fitting. Now I have a bubble to flare fitting that will rotate in any position. Bent up a new brake line with flare ends on both ends. It all worked the chain has plenty of room with the brake line and no chance of loosing the brakes when driving the car. If this were a production car this would be a called a safety recall. Still making improvements after all these years