| Author |
Message |
esde
Samba Member
Joined: October 20, 2007
Posts: 5969
Location: central rust belt
|
 Posted: Sat Dec 20, 2014 8:59 am Post subject: separating 3rd and 4th gear and drive hub |
 |
|
Can any of you point me to a picture showing how you set up the gear/ hub assembly on the press to separate them? I'm pretty far into my first transmission rebuild, and this has got me stumped. The gear and hub diameters are so close that there isn't a step to use, and the space between them so little that I don't see how a bearing splitter can work without causing damage. I've purchased loctite green sleeve retainer for the reassembly, any help getting it apart will be a huge help!
SD |
|
| Back to top |
|
 |
Type 5 Joe
Banned
Joined: January 18, 2003
Posts: 1795
Location: Oregon
|
| Posted: Sat Dec 20, 2014 9:24 am Post subject: |
|
|
Dremel and a carbide burr... Or milling machine if you have one. Split it and it will come out.
I would tig weld it back together again if you can. |
|
| Back to top |
|
|
esde
Samba Member
Joined: October 20, 2007
Posts: 5969
Location: central rust belt
|
| Posted: Sat Dec 20, 2014 9:50 am Post subject: |
|
|
| Well, yes that would work, except that I'm intending to re use the parts. Inspection shows that they're slightly worn on the drive side, and perfect on the other. Switching the hubs between 3rd and 4th gear will use the unworn good side of both hubs. But, how to get it apart? |
|
| Back to top |
|
|
jsturtlebuggy
Samba Member
Joined: August 24, 2005
Posts: 4496
Location: Fair Oaks/Orangevale, CA
|
| Posted: Sat Dec 20, 2014 10:17 am Post subject: |
|
|
First question is why are you removing the hub from the gear? If you are just removing to see how it done and then reinstalling it or are you replacing it?
Yes 4th gear is very close to same diameter as hub. A bearing splitter plate works with the flat side up to get hub off in a press.
Loctite will work to a point, but you need to heat hub to expand it (like what you do for a crank gear) for it to be a more interference fit.
As the power and torque increased, VW changed the way they installed the syncro hubs, from a press fit to first using brazing then electron beam welding.
With the early style hub you have, welding the hub on is really the only sure way to keep it from spinning.
Yes I have spun a hub on a gear using Loctite with only a 1200cc engine in a off road race car years ago.
Welding can be done with either a Tig or Mig. Using a Mig requires using shielding gas, Not flux core wire! You are trying to keep the heat down so as not to overheat the hub. Tig is a better option for keeping heat down. After welding gear needs to be hone (so it not tight on bearing) and surfaced on side where welding has be done.
The welds are short, either 2 or 4 small welds strips between the slots for oiling on hub. Also I add to extra oiling slots to get more oil to surface and bearing.
_________________
Joseph
Fair Oaks/Orangevale, CA
Elrod Motorsports
Motion Tire Motorsports
Having fun with Dune Buggies since 1970
Into Volkswagens since 1960 |
|
| Back to top |
|
|
esde
Samba Member
Joined: October 20, 2007
Posts: 5969
Location: central rust belt
|
| Posted: Sat Dec 20, 2014 10:54 am Post subject: |
|
|
| jsturtlebuggy wrote: |
Yes 4th gear is very close to same diameter as hub. A bearing splitter plate works with the flat side up to get hub off in a press.
Loctite will work to a point, but you need to heat hub to expand it (like what you do for a crank gear) for it to be a more interference fit.
|
I guess that I have to find a bearing splitter better matched to the diameter I am working with. Someone on STF has done some research on using loctite, and has found that using some abrasive on the mating surfaces in addition to the loctite made the fit stronger. Here's a quote from that thread:
"I did some tests. The first test was to bond them in exactly the condition the parts were made. Cleaned them well with Brake Kleen, then pressed them together with Loctite 680 spread evenly over both parts. Directions stated 24hr cure at room temp. I gave it a few more days. The reading I got when I pressed it apart converted to 400 ftlbs.
Next was to rough up the surfaces with some 60 grit sandpaper. I made sure not to lean on the parts to affect the press fit. Also note that every time you press the parts on and off, it wears out the press fit, so any reduction in grip could be due to that. However, this time it took more force to push the parts apart. Converted, I get 530 ftlbs. The sandpaper definitely helped."
I'm just building a stockish trans to go into a straight axle bus, nothing fancy. I bought hardened keys just because the original one (for the 3-4 drive hub) looked a bit hammered, other than that all stock parts. Looks like I'm asking for a bearing splitter for Christmas.. |
|
| Back to top |
|
|
modok
Samba Member
Joined: October 30, 2009
Posts: 26790
Location: Colorado Springs
|
| Posted: Sat Dec 20, 2014 11:03 am Post subject: |
|
|
3rd and low fourths should be easy just set on a piece of tubing the right size. A tube supports all the way around so even a small lip is enough. Tubing can be bought cheap from scrapyard and if you operate a press eventually you will collect plenty of scrap anyhow.
If the gear is bigger than the hub and you only have a tiny groove to support then may have to make a special tool.
Can go about that several ways. Machinist thinking is carve it out of a solid piece with much work.
My thinking is build it up from small parts. SO for instance take a big washer that is near the right size to fit into the tiny groove you have. Weld it to a tube. Cut in half. Then you can clamp it together on your piece with a few hose clamps or chain-grips. |
|
| Back to top |
|
|
[email protected]
Samba Member
Joined: May 17, 2003
Posts: 4863
Location: Harmony, PA
|
| Posted: Sat Dec 20, 2014 11:06 am Post subject: |
|
|
| A bearing splitter is what I use. I have taken a burr, and ground the radius of the opening close to the diameter of the gear. Also grind the surface touching the gear, and mating to pressing the hub at a 90 degree corner to keep the bearing plate from catching/dragging the gear teeth when pressing off the hub. You'll need a splitter that has the bolts through it, so you can snug it down on the side of the gear, but not tight enough to drag the teeth of the gear. Although switching the hubs will change the drive surfaces, if the worn surface is worn badly enough, then the trans will pop out of gear upon de-acceleration. The hub drive surface only wears 9 teeth in 3, 3 teeth sections that are wider than the others. It's better to remove the hubs, and grind the worn teeth completely off, then the slider will use the remaining non-worn teeth on the drive hub. And yes, if you're going this far, weld the hub back on. If you can't do the welding, and honing that may/may not be needed, find someone that can. |
|
| Back to top |
|
|
modok
Samba Member
Joined: October 30, 2009
Posts: 26790
Location: Colorado Springs
|
| Posted: Sat Dec 20, 2014 11:12 am Post subject: |
|
|
Good idea. If you can get some cheap chinese bearing splitters then grind to fit!! The good ones are a lot of cash tho.
Unlike epoxy..........the faster loctite cures the stronger it is, so a fresh sanded surface DOES make it work better. Even better if you don't clean it after sanding. Even the tiny bits of metal dust seem to help the cure!!! |
|
| Back to top |
|
|
jsturtlebuggy
Samba Member
Joined: August 24, 2005
Posts: 4496
Location: Fair Oaks/Orangevale, CA
|
| Posted: Sat Dec 20, 2014 11:23 am Post subject: |
|
|
Yes I read that on the STF too. Until it put in a vehicle with an engine that has the torque to really test it , I still will say welding the hub is really the only way to keep hubs from spinning.
Also by going to a straight axle instead of using reduction boxes, you are changing the torque applied to the gears inside the transmission.
The bearing splitter I have is from Snap-on (I have had for more than 30 years now). There are other good quality ones out there too. Proto and others make good ones. You may find good used one on line or in a use tool store too.
Also when I am pressing the hub off, once I have the hub moved up the gear a little, I reposition the splitter further under the edges of the hub.
Another thing that is done is the worn teeth on the hub (it usually 3 teeth spaced in 3 location around the hub) are cut off so that the other teeth contact the slider.
Long Enterprises www.longenterprises.com machines the sliders for full contact on all the teeth.
_________________
Joseph
Fair Oaks/Orangevale, CA
Elrod Motorsports
Motion Tire Motorsports
Having fun with Dune Buggies since 1970
Into Volkswagens since 1960 |
|
| Back to top |
|
|
Bruce
Samba Member
Joined: May 16, 2003
Posts: 17290
Location: Left coast, Canada
|
| Posted: Sat Dec 20, 2014 6:47 pm Post subject: |
|
|
| jsturtlebuggy wrote: |
Also by going to a straight axle instead of using reduction boxes, you are changing the torque applied to the gears inside the transmission.
|
The torque applied to the gears is from the engine. Changing the axles to reduction boxes doesn't change the engine.
To get the hubs off the gears, I use a short piece of 3" tubing from any muffler shop. Get it about 2" long, then cut it down it's length. Wrap a hose clamp around it's OD to adjust it to fit whatever ratio you're working with.
_________________
| overheard at the portland Swap Meet... wrote: |
| ..... a steering wheel made from a mastadon tusk..... |
|
|
| Back to top |
|
|
esde
Samba Member
Joined: October 20, 2007
Posts: 5969
Location: central rust belt
|
| Posted: Sat Dec 20, 2014 8:03 pm Post subject: |
|
|
| Bruce wrote: |
To get the hubs off the gears, I use a short piece of 3" tubing from any muffler shop. Get it about 2" long, then cut it down it's length. Wrap a hose clamp around it's OD to adjust it to fit whatever ratio you're working with. |
I was hoping there was a solution that was this easy. Thanks a million, and happy holiday. |
|
| Back to top |
|
|
jsturtlebuggy
Samba Member
Joined: August 24, 2005
Posts: 4496
Location: Fair Oaks/Orangevale, CA
|
| Posted: Sat Dec 20, 2014 9:02 pm Post subject: |
|
|
Bruce,
Maybe you should read about torque and how it applies all the way out to the tires contact on a surface.
_________________
Joseph
Fair Oaks/Orangevale, CA
Elrod Motorsports
Motion Tire Motorsports
Having fun with Dune Buggies since 1970
Into Volkswagens since 1960 |
|
| Back to top |
|
|
Bruce
Samba Member
Joined: May 16, 2003
Posts: 17290
Location: Left coast, Canada
|
| Posted: Mon Dec 22, 2014 7:50 pm Post subject: |
|
|
Maybe you should think about how torque is generated. The engine doesn't know what gearbox is hooked up to it. Talk to engine builders who dyno engines. Max load is max load, regardless of the gearbox.
_________________
| overheard at the portland Swap Meet... wrote: |
| ..... a steering wheel made from a mastadon tusk..... |
|
|
| Back to top |
|
|
Bruce
Samba Member
Joined: May 16, 2003
Posts: 17290
Location: Left coast, Canada
|
| Posted: Mon Dec 22, 2014 7:53 pm Post subject: |
|
|
| jsturtlebuggy wrote: |
Yes I have spun a hub on a gear using Loctite with only a 1200cc engine in a off road race car years ago.
|
Let me guess.... You were off roading and you jumped the car with your right foot to the floor. While in the air the engine quickly goes to redline. Then when you land, the tires instantly stop, creating a huge shock load that spun the gear.
I suggest Loctite for street cars.
_________________
| overheard at the portland Swap Meet... wrote: |
| ..... a steering wheel made from a mastadon tusk..... |
|
|
| Back to top |
|
|
mcmscott
Samba Member
Joined: March 12, 2010
Posts: 4858
Location: sanger ca
|
| Posted: Mon Dec 22, 2014 8:46 pm Post subject: |
|
|
If there is no resistance at the end of the gearbox then zero torque is generated, doesn't matter if there is a detroit diesel in front of it, no torque will be generated. There fore a lower gear ratio will have less chance of spinning a hub than a taller one, hence third has less chance of failure than fourth. Aparently Bruce doesn't understand this. And yes, I do have a dyno.
_________________
There are no stupid questions, only stupid people,
68 Ghia
67 T-1
65 Notch
02 Mexican beetle
74 Thing
15 Long travel rail
07 Nomad
05 f-250 |
|
| Back to top |
|
|
esde
Samba Member
Joined: October 20, 2007
Posts: 5969
Location: central rust belt
|
| Posted: Mon Dec 22, 2014 9:58 pm Post subject: |
|
|
The chunk of tubing, held tight with a hose clamp did the trick, thanks! Heated the hub and it reinstalled easily with some loctite as recommended. Next question, where are my options for when I need new 3rd/ 4th gear hubs? I know that Long Enterprises has them, just wondering if/ what other options there are.
SD |
|
| Back to top |
|
|
bugguy076
Samba Member
Joined: December 11, 2007
Posts: 1068
Location: Dover, PA.
|
| Posted: Wed Dec 24, 2014 5:03 am Post subject: |
|
|
I would just buy some broken trannys for spare parts. Most of the racing parts in the drag car tranny came from used broken trannys I bought or were given to me.
_________________
Grubby Fingers Racing
1976 Drag Bug
1967 Street Bug |
|
| Back to top |
|
|
Bruce
Samba Member
Joined: May 16, 2003
Posts: 17290
Location: Left coast, Canada
|
| Posted: Fri Dec 26, 2014 6:33 pm Post subject: |
|
|
| mcmscott wrote: |
| If there is no resistance at the end of the gearbox then zero torque is generated, doesn't matter if there is a detroit diesel in front of it, no torque will be generated. There fore a lower gear ratio will have less chance of spinning a hub than a taller one, hence third has less chance of failure than fourth. |
I see what you're getting at. Sure, at part throttle, the gear ratios affect how much torque the engine will make. But, IMO, that's not relevant to the topic at hand. If the synchro hubs are going to let go, it will happen at full throttle, not part throttle. And at full throttle, the max torque of the engine is the max torque the input shaft will ever see, regardless of what gear you're in. IOW, the torque applied through 3rd gear's synchro hub will be exactly the same as through 4th gear's synchro hub.
Why would the synchro hub let go while cruising down the freeway (engine making 40ftlbs of torque) and not 3 minutes before when you were at full throttle on the freeway on-ramp (engine making 80 ftlbs of torque)?
_________________
| overheard at the portland Swap Meet... wrote: |
| ..... a steering wheel made from a mastadon tusk..... |
|
|
| Back to top |
|
|
mcmscott
Samba Member
Joined: March 12, 2010
Posts: 4858
Location: sanger ca
|
| Posted: Fri Dec 26, 2014 7:01 pm Post subject: |
|
|
| Bruce wrote: |
| mcmscott wrote: |
| If there is no resistance at the end of the gearbox then zero torque is generated, doesn't matter if there is a detroit diesel in front of it, no torque will be generated. There fore a lower gear ratio will have less chance of spinning a hub than a taller one, hence third has less chance of failure than fourth. |
I see what you're getting at. Sure, at part throttle, the gear ratios affect how much torque the engine will make. But, IMO, that's not relevant to the topic at hand. If the synchro hubs are going to let go, it will happen at full throttle, not part throttle. And at full throttle, the max torque of the engine is the max torque the input shaft will ever see, regardless of what gear you're in. IOW, the torque applied through 3rd gear's synchro hub will be exactly the same as through 4th gear's synchro hub.
Why would the synchro hub let go while cruising down the freeway (engine making 40ftlbs of torque) and not 3 minutes before when you were at full throttle on the freeway on-ramp (engine making 80 ftlbs of torque)? |
It won't let go driving down the freeway, but will under full throttle. Due to gear ratio "multiplication" it will happen sooner in fourth than third. You will always have more load in fourth than third. If this wasn't the case you would just start in fourth gear.
_________________
There are no stupid questions, only stupid people,
68 Ghia
67 T-1
65 Notch
02 Mexican beetle
74 Thing
15 Long travel rail
07 Nomad
05 f-250 |
|
| Back to top |
|
|
Type 5 Joe
Banned
Joined: January 18, 2003
Posts: 1795
Location: Oregon
|
| Posted: Fri Dec 26, 2014 7:36 pm Post subject: |
|
|
From what I have seen.... Usually its 3rd gear spinning the hub.
Aggressive driving, speed shifting and "clutching" 3rd is usually the culprit.
Its called shock load. |
|
| Back to top |
|
|
|
