Betty blows another Tranny

[garryv84]

Are the SA transmission braces still available? Will they fit a 2wd 4speed tranny?

[gears]

There is no damaging "case flex" along the length of the transaxle. The purpose of the brace is NOT to add strength, but rather to help cancel out damaging vibrations.
_________________
aka Pablo, Geary
9.36 @ 146 in '86 Hot & Sticky
'90 Syncro Westy SVX
'87 Syncro GL 2.5
https://guardtransaxle.com

[kgold708]

[Jon_slider]

[snowsyncro]

[kgold708]

[IdahoDoug]

Gears,

I agree. I can't see "case flex" being a problem with this case - essentially a well braced large diameter aluminum tube under relatively low horsepower (even with the 5 cyl). If the theory is that engine shake is shaking the trans like a dog wagging its tail....? That has to be the theory, because there is no engine torque/power flexing the tranny - no such bending force is taking place.

So if it's literally the shaking diesel causing the tranny case to whip up and down, then two comments come to mind:

1 - where is the evidence this is happening in terms of internal parts failure?
2 - does anyone have any idea how much force it would actually take to actually whip/flex the transmission enough to damage internal parts by making shaft bearings no longer align momentariy? Hint: more than engine vibrations.


Finally, if this is the working theory now "the 5 cylinder diesel shakes so badly that it is whipping my trans up and down so violently it is flexing the case and damaging internal parts" then there's a WAY easier fix I alluded to earlier. Simply change the sympathetic resonance of the transmission by either using harder durometer front mounts (very easy to make), or hanging a mass damper off the front of the trans (I suggested a soup can).

A brace with the available room of a Syncro like that black one above is not going to do it. In fact, I'm going to get more direct. It's pitifullly and totally useless and here's why. You can flex a part like that more degrees than you can flex the case under it. In other words, the case it is attached to is more rigid than the brace. Does that translate? The brace is so small in cross section and of a softer metal that it will actually flex through more degrees than the much stiffer trans case. Structurally, it is literally as though you are using the trans case to stiffen the little hand made brace.

I hate always being the bearer of bad news, but look it up. You will find that a brace flexes until it reaches its elastic limit and then resists further flex. The aluminum trans case will flex much less in terms of degrees of angle before it reaches its elastic limit because it is a massive cross section structural member of a stiffer material. With that brace attached, the trans can happily flex up and down its limited amount without even bending the softer steel brace to its limit where the brace would then resist further flex. A total and complete waste of time.

DougM
_________________
1987 2WD Wolfsburg Vanagon Weekender "Mango", two fully locked 80 Series LandCruisers. 2017 Subaru Outback boxer. 1990 Audi 90 Quattro 20V with rear locking differential, 1990 burgundy parts Vanagon. 1984 Porsche 944, 1993 Toyota LandCruiser, 2002 BMW 325iX, 1982 Toyota Sunrader

[j_dirge]

I think I'd be looking to source a UN1......

Can't be that much more work than trying to brace the VW TA properly.
_________________
-89 GL Westy, SVX.. finally.

-57 pan f/g buggy with a 67 pancake Type 3 "S"
"Jimi Hendrix owned one. Richard Nixon did not"
-Grand Tour, Season 1, episodes 4 and 5

[snowsyncro]

[kgold708]

DougM,

You do realize that the factory brace is also far less stiff than the case right? From now on I'm calling it FRV (Flextural Resonate Vibration). I'll say it again, VW put that brace there for a very good reason that I don't fully understand. But I fix stuff that I don't FULLY understand all the time.
_________________
ASE Master Tech.
ASE L1 Advanced engine performance specialist.
ASE L2 Advanced electronic diesel engine specialist.

[gears]

There's a number of transaxles that could be stuffed into a Syncro, NONE of which offer low G gear and vacuum-locking differential. Betty needs those.

From a "strengthening" standpoint, that brace is worthless. But if it serves as a vibration dampner in any way, it could help. I was envisioning something stiffer, but I applaud any effort, given the lack of space.
_________________
aka Pablo, Geary
9.36 @ 146 in '86 Hot & Sticky
'90 Syncro Westy SVX
'87 Syncro GL 2.5
https://guardtransaxle.com

[Jon_slider]

[Phishman068]

10. Run factory CV's/axles for a while and see if they're breaking. If they're breaking, you've found your problem with your driving style and you can put your stronger ones back on transferring all that unnecessary torque back to the transmission (once fixing your driving style).

I'm glad there's a summary.

[kgold708]

Umm... has anyone mounted an AEL w/the 50deg. Bellhousing?
Edited to add:
11) replace SA bellhousing w/OG 1.6NA 50deg. Housing. Thus moving the primary combustion induced vibrational pattern out of alignment with the dominate local gravitational field.
_________________
ASE Master Tech.
ASE L1 Advanced engine performance specialist.
ASE L2 Advanced electronic diesel engine specialist.

[D Clymer]

[Jon_slider]

[kgold708]

[Jon_slider]

point counterpoint
below is an exchange with a 78 year old gentleman that has 34,000 miles on his AEL syncro turning 28" tires, with zero transaxle failures.

===
http://autos.groups.yahoo.com/group/TDI-conversion/message/18999
Jon,
 
I have 34,000 miles on my AEL (5 cyl) conversion, much of it in the mountains and deserts of the West, with with no T/A problems so far.  The stock rear tranny (T/A) was redone with different gearing by Darryl at conversion, and the front end was switched with a partial slip/decoupler rig.  I run with the front end disengaged most of the time, unless I need the extra 4WD traction offroad or for weather.  Don't know how much difference that will make from stock Syncro.
 
Just tossing in my experience with another AEL, in a modified Syncro.  Hope you come up with the bracing rig you're looking for.
 
Lou James
===

and later in the thread we compare our setups…

===
http://autos.groups.yahoo.com/group/TDI-conversion/message/19009
Hi Lou

thanks for taking your time to share info, very helpful, I add my info for the
benefit of the group
 
1.   how big are your tires  BFG AT 215 70R 16

* mine are MUCH bigger 245x75x16, and I use a 5.43 ring and pinion, instead of
your 4.86
 
2.   at 3000rpm, what is your GPS speed in 4th gear  I have checked that with
GPS years ago but can't find my record.  I don't have a GPS now and don't know
anyone with one to recheck.  If I find one, I'll check it and let you know.  The
stock speedo reads about 64 mph @ 3000 rpm in 4th.  Using mile markers on an
Interstate, I've calculated that it's reading about 5 % low (about 68 mph
true). 

* Im at 70mph@3000rpm 
 
3.  what is your EGT at 3000rpm in 4th, flatland (and sea level)  At about 62
degrees F. ambient, the EGT averages about 690 degrees F. 

* I cruise at 600F
 
4.  what is the maximum EGT, and what minimum RPM do you allow before
downshifting on highway hills  I've never pushed the EGT to max.  I don't
remember ever pushing it over about 1250 degrees F., and then only momentarily. 
I keep it pretty much under 1000 degrees F., as Tom suggested, and I don't use a
fixed rpm for downshifting.  I shift down when I see (or hear) the revs dropping
at full throttle unless the crest of the hill is only a very short
distance away.  I just don't let it lose revs on hills.  I don't lug the
engine.  The tach never drops below 1500 rpm.

* I am guilty of letting the motor lose revs on hills. I have been allowing it
to drop to 2000rpm, and I have allowed EGT of 1000.
 
5.  do you drive like an old lady  I stay with or ahead of the traffic from
stops most of the time, but I don't pop wheelies

* I also don't do wheelies, and drive like an old lady. I have been extremely
gentle with my beast, but she continues not to be a Beauty.
_________________
My Soapboxes: Inflation; Handling; Gearing; Decoupling; Swepco

[IdahoDoug]

KGgold,

The brace I'm criticizing as ineffective is the small black hand made one, which is NOT a factory brace (someone correct me if I'm wrong here), it won't add stiffness to the case, and it won't act as a harmonic damper any more effectively than a chunk of metal of the same weight/size. Which is very little, and the better place for a chunk of mass for harmonic damping is near the front where the movement would be maximized.

Ron,

As for the SA guys swearing up and down good results. If you were my friend and you were going to run off to a shop and pay someone to build and install that part, I would pull you aside, look in your eyes and kindly say "there is no way that is stiffening the trans case in any meaningful way. Simply no way." Because there are people (maybe some on here right now) who will swear that this reduced trans case flex (with no objective data), I will be polite and not back someone in a corner. It defies the simplest of physics to say a short part made of a softer material is stiffening a huge long part made of a stiffer material that has a very high sympathetic resonance.

The factory brace that is tube-like and goes from the upper bellhousing to the front of the trans on 2WDs is from what I understand the "factory stiffener." This is an excellent design and would help the tranny resist both flexing and vibrating. Unfortunately it will not fit on a syncro.
_________________
1987 2WD Wolfsburg Vanagon Weekender "Mango", two fully locked 80 Series LandCruisers. 2017 Subaru Outback boxer. 1990 Audi 90 Quattro 20V with rear locking differential, 1990 burgundy parts Vanagon. 1984 Porsche 944, 1993 Toyota LandCruiser, 2002 BMW 325iX, 1982 Toyota Sunrader

[Alaric.H]