Ruined transmission (a tale of torque and woe).

Post by **Growlerbearnz** » Tue Oct 24, 2017 9:47 pm

I think I'm going to throw up.

: 20171025_150414.jpg (60.6 KiB) Viewed 7426 times

That's the inside of my transmission, which was rebuilt in January: 20,000km ago. Yesterday it started shifting strangely, then it went *bang* and I only had 2nd gear.

The rebuild guys don't know yet what went wrong, but they warned me that it might be a consequence of the extra torque from my brand-new and power-tuned D4BF (which isn't covered by warranty, and fair enough too.) The size of the metal chunks means the transmission is very likely a writeoff- those pieces are just what's made it through the torque converter and transmission coolers, there's far worse still chewing up the gears and bearings.

Tomorrow I'm buying a manual L300 as a donor.

ACKO15 · Post by **ACKO15** » Wed Oct 25, 2017 8:25 am

Oh no!

My sincerest condolences. That's the worst luck. I sure hope some solution can be found. I feel so terrible just looking at the damage.

javabob · Post by **javabob** » Wed Oct 25, 2017 10:24 am

Oh no Growler! I threw up in sympathy for you. I am so sorry.
Wish I could smoke some bbq and deliver some beer to you and yours.

Hang in there Growler!

lrp374 · Post by **lrp374** » Wed Oct 25, 2017 10:42 am

Sorry to see your mess Golden Growler. I noted @ the top of the L300 section you had a recent comment on the use of Dexron IV vs III. Do you think this could have contributed to your problem? As an aside I read somewhere that these transmissions are supposed to be rated for 300 HP. Obviously it must have been an unreliable source!!

north54 · Post by **north54** » Wed Oct 25, 2017 10:49 am

Sorry to see this brother! I say we start a gofundme page for Growler to get him some support getting back on the road faster!

Post by **Growlerbearnz** » Wed Oct 25, 2017 1:08 pm

lrp374 wrote:I noted @ the top of the L300 section you had a recent comment on the use of Dexron IV vs III. Do you think this could have contributed to your problem?

Possibly, the shifts were quite a bit harder with the Dexron VI in there. It could be that something made of steel couldn't handle the hammering and broke. If the clutches had worn out I'd say definitely.

lrp374 wrote:As an aside I read somewhere that these transmissions are supposed to be rated for 300 HP. Obviously it must have been an unreliable source!!

The Volvo guys use the same transmissions behind some big turbo motors, and they're reliable as long as you don't go drag racing. I suspect it's the torque that's killed this one- turbo gas engines only make their power at high revs, where my diesel is making peak torque around 1800rpm.

north54 wrote:I say we start a gofundme page for Growler to get him some support getting back on the road faster!

I'm grateful for the concern, but please don't do that. It's all under control. Tonight I pick up a 1995 manual L300 and start swapping the bits over. We'll get a "how to convert from automatic to manual" (or possibly "why you can't convert from automatic to manual") tutorial out of it.

...and if my recent luck holds, it'll be followed by "how to rebuild a V5M21 gearbox".

TieMyShoe · Post by **TieMyShoe** » Wed Oct 25, 2017 7:19 pm

How much power are you putting down Growler? My 4D56 in its current setup is just a shade quicker than my buddies 4M40 SWB from a standing start and dead even at a roll. It runs out of power around 140KPH unloaded. Have not had a chance to dyno it. However the VW TDI motor will be putting down roughly 153whp 273wtq... I thought the trans would be able to handle it but now I'm concerned. From what I had researched the 5Spd STD was weaker than the autobox.

Post by **Growlerbearnz** » Thu Oct 26, 2017 12:52 pm

I haven't had mine on a dyno either. The upper limit for the VE injection pump is 100kw (130hp) at 4500rpm (it just can't pump any more fuel than that). Torque feels about the same as a friend's Triton, which is supposed to make 320Nm (though my power drops off after 3000rpm where the Triton just keeps pulling).

That said, we don't know what went wrong yet. I'm leaning towards the hard 1st-2nd shift breaking something. Once it was moving it certainly didn't slip or overheat, even at 2000rpm with a heavy load.

The problem I have now is the transmission rebuilders want to look at it, but if it turns out it failed because of something I did they'll want to charge me for their time. Since I now have a manual Delica in the driveway I don't think I want to chance the extra expense. Maybe I'll disassemble it myself and just ask them to look at the parts.

The KM147 5-speed is known to be weak, with an undersized 5th gear that likes to split. The KM147 was modified in 1990 to address these issues, and was renamed the V5M21 (larger 5th gear, stronger bearings). In theory if it has a hydraulic clutch and was built after 1990 it should be more durable. We'll find out, I guess.

Post by **Growlerbearnz** » Wed Nov 01, 2017 3:51 pm

And the results are in: a spectacularly failed overdrive gearset, finished off for good when a chunk of gear tooth got stuck in the OD brake pack, jamming it on.

Likely cause of failure: excessive torque.

The moral of the story: don't use overdrive under heavy load (hauling stuff up hills, overtaking) even if you have the torque to do so.

And now, because it's Halloween, something to give you nightmares:

: OD.JPG (272.08 KiB) Viewed 7275 times