Speed Limiter / Governor Safe Tweaks

[EastCoastCB]

Originally Posted by Booyah45828

Yeah, Charlie, I haven't figured out what's going on with your bus yet.

It must have some sort of aftermarket low stall converter in it because all the converters that I've seen that allison spec'd from the factory are all way too loose for you to be doing what your doing.

Allison had a minimum full-load engine governed speed of 2400. That means they want engine rated hp at that # or above. So the torque converters they used reflect that, which is why most engines with the at545 seem to be ran higher in the engine rpm range.

You can put a lower stall converter in it, and it's not a bad idea to do so, so long as you're easy on it. We did that with a pulling truck and an at545 and slipped/burned up the clutches because we applied too much power at too low of an rpm.

Far as I can tell its a reman with the tag on it. My engine's redline is 2400, maybe these buses came with a lower stall converter?

[turf]

maybe try a stall test , see if this upload helps or works but ......

[cadillackid]

when I put a pressure gauge on an AT545 it built full pressure at about 2000 RPM on both my 545s.. even my broken and wouldnt move 545 built line pressure at the same rate..



onto charlie.. the pic isnt reflective of full load.. his engine is at partial load. or is against a speed limiter.. althiough i thinkl he said there is no speed limiter.. so the real test is to run it up to 65 and punch the throttle and take a pic once the turbo spools and the engine is pushing out real load against the converter.. look at the RPM then..

a ground-stop stall speed test wont tell you much. my ground stop stall testing on mine came back with around 1300-1400 without pushing things super hard.



there were only 2 converters made for the later 545s.. a Gas and diesel.. TC-275 and TC-290. since his trans is a reman no idea which is in it ..


incidently the AT540/545 share a lot of commonalities in design with the TH-400 GM trans.. ive been told some of the same converters were interchangeable.. never looked into it any deeper than guys with farm trucks that talked of it.

[Booyah45828]

Originally Posted by cadillackid

when I put a pressure gauge on an AT545 it built full pressure at about 2000 RPM on both my 545s.. even my broken and wouldnt move 545 built line pressure at the same rate..

Same thing we saw. Applying full throttle (cummins 12v) with our tight converter roasted the forward clutch and steels. Too much power applied for not enough clamping. The pump didn't have enough volume to make the pressure we needed. Rev it up more past peak torque and it did fine, you just couldn't lug the thing down to peak torque. Which is why I feel the torque converters are all designed to be loose.

Originally Posted by cadillackid

incidently the AT540/545 share a lot of commonalities in design with the TH-400 GM trans.. ive been told some of the same converters were interchangeable.. never looked into it any deeper than guys with farm trucks that talked of it.

That's the converter source that we used. 6 bolt th400. I forget the stall rating but it did lower it to about 1400 rpm. Got it special order from tci at the time.

[Sleddgracer]

Originally Posted by cadillackid

when I put a pressure gauge on an AT545 it built full pressure at about 2000 RPM on both my 545s.. even my broken and wouldnt move 545 built line pressure at the same rate..



onto charlie.. the pic isnt reflective of full load.. his engine is at partial load. or is against a speed limiter.. althiough i thinkl he said there is no speed limiter.. so the real test is to run it up to 65 and punch the throttle and take a pic once the turbo spools and the engine is pushing out real load against the converter.. look at the RPM then..

a ground-stop stall speed test wont tell you much. my ground stop stall testing on mine came back with around 1300-1400 without pushing things super hard.
there were only 2 converters made for the later 545s.. a Gas and diesel.. TC-275 and TC-290. since his trans is a reman no idea which is in it ..


incidently the AT540/545 share a lot of commonalities in design with the TH-400 GM trans.. ive been told some of the same converters were interchangeable.. never looked into it any deeper than guys with farm trucks that talked of it.

does the TH-400 GM trans. lock up? - my inexperienced bit of knowledge says yes, but I don't know for sure

[Booyah45828]

Originally Posted by Sleddgracer

does the TH-400 GM trans. lock up? - my inexperienced bit of knowledge says yes, but I don't know for sure

No, it did have a torque converter option that had a switchable stator angle, but never a lock up clutch.

[Sleddgracer]

Originally Posted by Booyah45828

No, it did have a torque converter option that had a switchable stator angle, but never a lock up clutch.

thanks ...................

[Sleddgracer]

Originally Posted by Booyah45828

No, it did have a torque converter option that had a switchable stator angle, but never a lock up clutch.

my 88 gmc pickup would lock up/unlock, back and forth, at certain speeds at no acceleration/no deceleration - it could be annoying at times - later models corrected that minor problem

[cadillackid]

There was a th350C which was a lockup 3 speed but I don’t remember one of the 400.
I had an Oldsmobile with it, was a terrible setup as the lockup was electric based on vacuum so the result under certain conditions was constant lock and unlock. My car had a carb and a 307 V8.
Christopher

[Sleddgracer]

Originally Posted by cadillackid

There was a th350C which was a lockup 3 speed but I don’t remember one of the 400.
I had an Oldsmobile with it, was a terrible setup as the lockup was electric based on vacuum so the result under certain conditions was constant lock and unlock. My car had a carb and a 307 V8.
Christopher

........................................

[rabryant1]

Originally Posted by drew78634

Any update on this problem? Did you find a solution?

Drew

We have not, we also haven't looked into it much, been too busy on the conversion. The couple of diesel shops we've had it to for other stuff have not had the equipment to re-program the engine, citing something about being something that can only be accomplished at a dealer.