MD-3060R Transmission - sluggish 1st gear

Topic: MD-3060R Transmission - sluggish 1st gear (Read 1451 times) previous topic - next topic

MD-3060R Transmission - sluggish 1st gear

August 17, 2018, 05:11:51 pm

Another thread discussing torque converter locking reminded me of a question I've been meaning to ask. Sometimes my coach is very responsive in accelerating from a full stop and other times it's very sluggish. To the point of being dangerous to make a left turn across traffic when I don't know if it's going to actually "go" or not. From what I understand, my transmission starts 1st gear in torque converter mode, then changes to lockup when it feels like it. It seems like this transition to lockup takes much longer when leaving from a stop sign, for instance, than from a red light where it's had more time to think about it. It also seems like it might be related to how much the retarder was involved in the stop. Like maybe fluid that was diverted to the retarder needs time to redistribute before 1st gear is responsive again? All of that is pure speculation on my part, based on the symptoms I think I'm seeing. It's been like that for as long as I can remember, so I don't think it's a "problem" and I'm not having any other transmission issues. Is this just the way it works?

Re: MD-3060R Transmission - sluggish 1st gear

Reply #1 – August 17, 2018, 05:21:21 pm

Not aware of any Allison transmission locking in 1st gear. The "mini-shift" in the upper range of 2nd gear is the torque converter locking.

Torque converter is locked in all higher gears.

Any diagnostic codes when/after this happens?

Re: MD-3060R Transmission - sluggish 1st gear

Reply #2 – August 17, 2018, 05:23:39 pm

You have a six speed so it should fly right off the line. Usually, slow starts are fuel delivery problems but just a guess. Low boost pressure can mean a few reluctant feet until the turbo has spooled up. Do you get any black smoke out the back when coming off a stop sign? Altitude generally means slower off the line.

Pierce

Re: MD-3060R Transmission - sluggish 1st gear

Reply #3 – August 17, 2018, 05:26:08 pm

I got the idea that it had a 1st gear lockup from the following information in an Allison 3000 series document. I might have misinterpreted it, or it might not apply to my 3060.

https://www.allisontransmission.com/docs/default-source/specification-sheets/int3000_sa5341(201306)blk.pdf?sfvrsn=2

Shift Sequences [C = Converter mode (lockup clutch disengaged); L = Lockup mode (lockup clutch engaged)]
Option 1: 1C–[1L]–2C–2L–3L–4L
Option 2: 1C–[1L]–2C–2L–3L–4L–5L
Option 3: 1C–[1L]–2C–2L–3L–4L–5L–6L

No codes that I'm aware of but I haven't gone into the diagnostics to look.

Re: MD-3060R Transmission - sluggish 1st gear

Reply #4 – August 17, 2018, 05:28:31 pm

Quote from: Pierce & Gaylie Stewart – August 17, 2018, 05:23:39 pm

You have a six speed so it should fly right off the line. Usually, slow starts are fuel delivery problems but just a guess. Low boost pressure can mean a few reluctant feet until the turbo has spooled up. Do you get any black smoke out the back when coming off a stop sign? Altitude generally means slower off the line.

Pierce

No smoke. Engine ramps up fine, it's just not getting to the wheels right away some times. Same at sea level or at altitude.

Re: MD-3060R Transmission - sluggish 1st gear

Reply #5 – August 17, 2018, 07:44:51 pm

Check fluid level with touch pad...and for now ignore dipstick reading until you are sure it is calibrated. Slightly low fluid level could give you this symptom.

Ralph
96 U270

Re: MD-3060R Transmission - sluggish 1st gear

Reply #6 – August 17, 2018, 09:01:12 pm

Are your fuel lines original?

Re: MD-3060R Transmission - sluggish 1st gear

Reply #7 – August 17, 2018, 09:14:54 pm

Fuel lines have been replaced.

Re: MD-3060R Transmission - sluggish 1st gear

Reply #8 – August 17, 2018, 09:32:13 pm

do you still have the Winn fuel filter system?

Re: MD-3060R Transmission - sluggish 1st gear

Reply #9 – August 17, 2018, 10:00:44 pm

All original fuel filter system

Re: MD-3060R Transmission - sluggish 1st gear

Reply #10 – August 17, 2018, 10:26:22 pm

Winn's are notorious leakers, suck air. Replace. Period

Bypass the filter. Drive.

Re: MD-3060R Transmission - sluggish 1st gear

Reply #11 – August 18, 2018, 09:26:36 am

I'm not opposed to replacing the Winn but are you suggesting it's the cause of the issue I'm having? I suppose it could be engine related, although it sure feels more like the transmission. If it's the filter sucking air, wouldn't I be having rough running at all speeds? The only time I know that this is happening is from a dead start at idle, and then only under the conditions I described previously. The engine never runs rough, as I would expect with air in the line. As another example, if I exit a highway and use the retarder coming off the ramp to stop at the stop sign, if I haven't waited long enough at the stop sign, the coach is harder to get moving than if I wait for 10 seconds or so. Since I usually do use the retarder I'm not 100% if it happens this way without it but I don't think so. I'll have to pay more attention to that and the engine next time.

Another scenario that could make sense in my mind, if it's not transmission related, is possibly just low fuel pressure? Maybe as the engine is slowing the coach, fuel pressure drops for some reason, and takes a little time to recover?

I'll check for other threads about replacing the Winn.

Thanks.

Re: MD-3060R Transmission - sluggish 1st gear

Reply #12 – August 18, 2018, 10:03:13 am

Next time you use the coach do as you suggested and stop without the retarder a few times to see if the problem persists. Sucking air through the Winn filter would be more noticeable pulling a grade or a no start issue. I am still using the Winn and have a replacement for it if and when it fails. My Monaco used the same filter and it never failed while I owned it.

Re: MD-3060R Transmission - sluggish 1st gear

Reply #13 – August 18, 2018, 10:05:39 am

Check the 2 return springs near your fuel solenoid could be causing a problem.

Re: MD-3060R Transmission - sluggish 1st gear

Reply #14 – August 18, 2018, 10:42:59 am

Quote from: bdale – August 18, 2018, 09:26:36 am

Another scenario that could make sense in my mind, if it's not transmission related, is possibly just low fuel pressure? Maybe as the engine is slowing the coach, fuel pressure drops for some reason, and takes a little time to recover?
Thanks.

No, the fuel pressure won't drop as you slow to cause a problem when you start back up. You could bypass the filter for a trial without removing it. Removing it seems extreme if it turns out not to be the culprit.

Call Allison and describe your symptoms.

Pierce

Re: MD-3060R Transmission - sluggish 1st gear

Reply #15 – August 18, 2018, 11:37:00 am

Quote from: bdale – August 18, 2018, 09:26:36 am

As another example, if I exit a highway and use the retarder coming off the ramp to stop at the stop sign, if I haven't waited long enough at the stop sign, the coach is harder to get moving than if I wait for 10 seconds or so. Since I usually do use the retarder I'm not 100% if it happens this way without it but I don't think so.

bdale,
Go and look at your retarder accumulator air valve vent. Make sure it isn't stopped up. If it is stopped up it can give some of your symptoms. Here is a link to how you remove and clean if need be. Allison retarder air valve

Mike

Re: MD-3060R Transmission - sluggish 1st gear

Reply #16 – August 18, 2018, 01:27:15 pm

Uneven acceleration can be myriad things. Lots of parts. My Winn vacuum leaked as did almost all. Repaired it twice. Scrapped it finally,

The Cummins shop bypasssd it by rerouting the hoses.

My coach had starting issues from air in the lines. Especially with less than a full tank and/or with the nose down and the engine off for a while.

Ran fine with a full tank.

Cummins mechanic had worked on a truck fleet with the Winn's and remembered the issues and rerouted the hoses and reran the coach on the dyno and picked up 50hp.

I thought it was slow. The starting was a separate but related symptom

Re: MD-3060R Transmission - sluggish 1st gear

Reply #17 – August 19, 2018, 12:26:02 am

If you have the Cummins mechanical C8.3, your coach likely uses an electric King Throttle Control. Could this be slow to pull back on throttle cable. You could have someone look with bed up when taking off. All slack should be removed on cable, which can be manually observed by pulling on cable.

King will also go in low-rpm (limp-mode) if it does not see a ground through the brake light bulb. Do you have led brake lights or a poor bulb connection.

Re: MD-3060R Transmission - sluggish 1st gear

Reply #18 – August 19, 2018, 11:26:06 am

My C8.3 is very responsive from a stop. But at other times from a dead stop; I want to take off fast, I floor it. And it refuses to respond. What are we doing wrong? Usually when I floor it, it is to avoid something so it really makes me mad. My 2016 F150 will respond to full throttle at any speed. It has had fuel lines replaced, and it will run 80mph with no problems. It is the dead stop lack of response that is my biggest complaint. I should have bought Dave Metzer's FT; I bet it does not do that.

Re: MD-3060R Transmission - sluggish 1st gear

Reply #19 – August 19, 2018, 11:51:06 am

These engines do not respond like a car,it's me but I don't think I ever floored it from a stop,no reason to except emergency,
check all the above things and get a resonator if you want every drop of power.

Re: MD-3060R Transmission - sluggish 1st gear

Reply #20 – August 19, 2018, 10:41:22 pm

My guess is you are attributing the slow acceleration to the transmission instead of the likely cause of turbo lag.

Re: MD-3060R Transmission - sluggish 1st gear

Reply #21 – August 19, 2018, 10:54:19 pm

My 98 c8.3 is often slower than I think it should be pulling away from stop sign. After a slow start it picks up, but no pulling out in traffic like a car. I've just learned to leave more room. It surprised me the first few times, try to remember that I'm not driving a car.

Re: MD-3060R Transmission - sluggish 1st gear

Reply #22 – August 20, 2018, 08:45:20 am

Quote from: Pamela & Mike – August 18, 2018, 11:37:00 am

bdale,
Go and look at your retarder accumulator air valve vent. Make sure it isn't stopped up. If it is stopped up it can give some of your symptoms. Here is a link to how you remove and clean if need be. Allison retarder air valve

Mike

Where is the retarder accumulator valve? I looked for it yesterday but didn't find it.

Re: MD-3060R Transmission - sluggish 1st gear

Reply #23 – August 20, 2018, 09:16:08 am

X2 on Barry's post it is very similar to what I was experiencing. I chased the fuel system and even had the King rebuilt before finding the issue was the brake light. Open the first bay on the drivers side. Look on the bulkhead on the left. You will see two round switches. Check and clean them. Nice to rule this out up front. I posted the whole experience. Also cites Chucks "Science experiment" on fuel system.

Intermittent power 97 270 KC2600 not fuel

I originally thought I was having a transmission issue 4 months earlier and had an Allison tech check it. No faults etc.

Re: MD-3060R Transmission - sluggish 1st gear

Reply #24 – August 20, 2018, 09:54:13 am

I have a Cat 3126, not a Cummins. I don't think I have the King Throttle Control.

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