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oldmanmark
Samba Member
Joined: July 08, 2006
Posts: 842
Location: n.w. indiana,chicagoland
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 Posted: Fri Sep 10, 2010 11:01 am Post subject: swingaxle or irs trans strength |
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| the vw virus in my arteries feeds off my time! will be getting my 1904 in a while. around 100 hp,bit more torque. i got a 72 irs trans from a field find. the swing in the 63 i believe is a 66, so 4:37 r/p. ratio is not my ?, its the strength of the two type of trans,not the handleing or ride quality. its a daily driver,no racin,clutch popn, just sprited driveing up to 5k anytime and watching the others facial expressions. the stronger of the 2 transmissions is ? i got enought to do, not includeing a swap. if you done a swap yourself are you glad you did? |
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Almost Alive
Samba Member
Joined: October 12, 2009
Posts: 1345
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| Posted: Fri Sep 10, 2010 1:14 pm Post subject: Re: swingaxle or irs trans strength |
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| oldmanmark wrote: |
| the vw virus in my arteries feeds off my time! will be getting my 1904 in a while. around 100 hp,bit more torque. i got a 72 irs trans from a field find. the swing in the 63 i believe is a 66, so 4:37 r/p. ratio is not my ?, its the strength of the two type of trans,not the handleing or ride quality. its a daily driver,no racin,clutch popn, just sprited driveing up to 5k anytime and watching the others facial expressions. the stronger of the 2 transmissions is ? i got enought to do, not includeing a swap. if you done a swap yourself are you glad you did? |
If your talking stock vs. stock than swing is stronger.
With the HP your going to be putting out you've got nothing to worry about either way. Both set ups will work fine.
If your pan is a SA, use the SA. If its IRS, use the IRS. |
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oldmanmark
Samba Member
Joined: July 08, 2006
Posts: 842
Location: n.w. indiana,chicagoland
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| Posted: Fri Sep 10, 2010 11:19 pm Post subject: |
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| AlmostAlive thats pretty much what i wanted to hear. with the body currently off and the availability of the irs i'm weighing out all posibilities, so no regrets later. got enough to do. thanks. |
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donmurray
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Joined: December 30, 2008
Posts: 841
Location: Frisco Texas
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| Posted: Sat Sep 11, 2010 7:26 am Post subject: |
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| I thought late model transmissions were stronger. Beetles (USA) from about 72 or 73 had the single side cover trans which is stronger. 73 on had furnace welded/brazed gear hubs. Buses had them welded starting in 71. All German made VW after 10/72 had the better 9 tooth main shaft. |
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oldmanmark
Samba Member
Joined: July 08, 2006
Posts: 842
Location: n.w. indiana,chicagoland
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| Posted: Sat Sep 11, 2010 9:50 am Post subject: |
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| mark, look at all the worms in that can. i heard sorta same thing too,not as detailed though, a 72 or 73 was strongest trans made. i rationalized it as just the trans and not the entire axle/trans assimbly. also hear swing is stronger than irs,as in entire axle/trans assembly. so i figure 72-73 years are exception to this=strongest trans period. so for me, i weigh it all out if a swing to irs really,really worth extra work then seriously consider, the bodys off now. reality=sounds like i need a more powrful engine to take advantage of a stronger irs trans swap,not this 100hp-100+ tq engine. possibly use on next project. got enough to do. |
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mark tucker
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Joined: April 08, 2009
Posts: 23937
Location: SHALIMAR ,FLORIDA
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| Posted: Sat Sep 11, 2010 10:11 am Post subject: |
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| then have rancho build a good one,type 2 cv's. |
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Bruce
Samba Member
Joined: May 16, 2003
Posts: 17290
Location: Left coast, Canada
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| Posted: Sat Sep 11, 2010 1:55 pm Post subject: |
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| donmurray wrote: |
I thought late model transmissions were stronger.
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In the context of this question, a 72 double side cover IRS is not much stronger internally than a 66. The ring gear on the later is held on with 8 bolts instead of 6. The 4.12 of the 72 is stronger than the keyed 4.37 in the 66. On the other hand, the 66 will have a steel 1-2 shift fork instead of brass like the 72 has.
Here's some VW trans history.
The tunnel trans first appeared in a Bug in 61. As the years went on, VW constantly made improvements. So therefore, the newer you get, the better. .......usually. There are a very few exceptions, like the fork I noted above. The following only applies to German made Type 1 gearboxes. Brazilian made ones are their own pile of junk.
*61-63 gearboxes used a ball bearing pinion bearing. These gearboxes are junk and should not be used in any car with more than 40hp.
Another big problem with them is the cantilevered 1-2 shift rod. The fork is hanging waaaay out on the end of this rod, so the bore in the gear carrier is subject to a LOT of wear. Once there's lots of wear, the fork can wobble around. This pulls and pushes on the 1-2 slider, causing it to pop out of gear.
On top of all that, the 1-2 slider is 1mm wider on these early gearboxes, so it has ˝mm less engagement than later sliders.
The first gear idler is much narrower than later gears. Weaker.
First gear synchros are not available for these early firsts.
*By about 65 or 66, most of these glaring early problems were fixed. From then on, VW began making the gearboxes stronger. By 67, the ring gear was up to 8 bolts, and the R&P was the stronger 4.12 to better suit the bigger 1500cc engine. The only step backwards was the introduction of the brass 1-2 shift fork. I guess they figured brass would wear better. Problem is, brass is brittle, and they break all the time.
*In 1970, VW changed the pinion bearing again. It has a larger OD so it is better supported in the case. And it is held in by the large ring nut instead of the 4 bolts. The ring nut spreads the clamping load evenly around the bearing, rather than concentrating it in 4 points.
*69 or 70 was also the time when VW changed 3rd and 4th to the fine tooth gears. The individual teeth are weaker than the coarser teeth the early gearboxes have, but there are many more of the fine teeth in contact at any given instant, so the overall strength isn't compromised. Many people will argue the whole gear is way weaker. I disagree. What happens is that when there's a chunk of steel floating around in the oil, when it gets caught between the fine teeth, they chip off. Many times only a corner. This now introduces a second chunk of steel floating around. Then a third......... So if you beat on your gearbox and don't change the oil, you'll likely have trouble with fine tooth gears.
*In 71 VW changed the throw out bearing to a type with integral clips. IMO this is one of the best upgrades they did. If you have a 1970, you can easily upgrade to the later TO bearing.
*73 saw the most changes in one single shot. The obvious is the much stronger single side cover trans case.
Stronger bits in a 73:
First gear : 9 tooth instead of 10
Diff gears : 15 teeth instead of 17
Spiders : 10 instead of 11
IRS side cover : extra reinforcement ring
TO bearing cross shaft : 19mm instead of 16mm
Pinion bearing : 002 type instead of 113 type (both with the ring nut)
Clutch arm : 90mm instead of 73mm (for much less pedal effort)
1-2 shift fork : back to steel, however, some still had brass.
3rd and 4th gears : furnace brazed synchro hubs (no more welding)
3-4 slider: longer dog teeth for deeper engagement
3.88 R&P : Strongest of all
All of these upgrades also happened to swing axle gearboxes (where applicable), so starting with a 73 swing is a very good choice.
*In mid 75, VW again increased the clutch arm for even less pedal effort. The side cover got another upgrade with another reinforcement ring.
*In 76, VW used a bunch of Bus 091 parts in the Bug gearbox.
Pinion bearing
Mainshaft bearing
1-2 shift hub
Reverse idler shaft and reverse idler gear.
The 091 pinion bearing is a big upgrade. Previously, the rollers were the same on each side 11mm wide (for the 002). Some bright engineer then realized that the load is predominantly from the diff side, so they changed the bearing to increase the size of the rollers on the diff side to 13mm to better support the load. The other side was reduced to 10mm, presumably to make it all fit.
Enough rambling for now.....
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| overheard at the portland Swap Meet... wrote: |
| ..... a steering wheel made from a mastadon tusk..... |
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vwracerdave
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Joined: November 11, 2004
Posts: 15308
Location: Deep in the 405
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| Posted: Sat Sep 11, 2010 3:15 pm Post subject: |
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Bruce
How would you compare a late SSC AT trans to a AV Thing trans as far as strength.
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2017 Street Comp Champion - Thunder Valley Raceway Park - Noble, OK
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Bruce
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Joined: May 16, 2003
Posts: 17290
Location: Left coast, Canada
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| Posted: Sat Sep 11, 2010 3:24 pm Post subject: |
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| vwracerdave wrote: |
Bruce
How would you compare a late SSC AT trans to a AV Thing trans as far as strength. |
Other than the R&P and the flanges, there's no difference. A 73-74 AV is exactly the same as a 73-74 AT trans.
You do get bigger flanges with the AV so you can use Bus or Thing CVs.
The AV is usually an O type 4.12 R&P, which is almost as strong as the common G type 3.88 R&P in the AT. However, don't bet the rent on getting an O type in an AV. Many are G type R&Ps.
The only other difference I can think of is the nose cone. AV used the early one, AT the late one.
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| overheard at the portland Swap Meet... wrote: |
| ..... a steering wheel made from a mastadon tusk..... |
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