Can We Have A Manual Down-Shifting Discussion?

Topic: Can We Have A Manual Down-Shifting Discussion? (Read 1363 times) previous topic - next topic

Re: Can We Have A Manual Down-Shifting Discussion?

Reply #25 – August 06, 2020, 07:28:10 pm

Quote from: craneman – August 06, 2020, 07:07:03 pm

Lots of double clutching on trucks going from the main to the brownie. Never had any cars with flat gears.

Early VW and then first gear in most English cars, AH Sprite, Jaguar. When I was a kid, I worked in a foreign car garage with lots of Jags. The manual was terrible but Borg Warner made the automatic and it was great. The 3.8 sedan with automatic was a fantastic car. Fast and with the interior of a Rolls Royce.

I was the guy that had to teach the new guys how to drive crash boxes. Several had automatic Hondas so the transition to a crashbox and a huge fire truck was difficult to say the least. No parking lots, just had to leave the station onto city streets on their first drive. Usually started with a 1943 Mack with juice brakes. After a few hours, it was time to stop and then start on a steep hill without rolling back (no air brake valve on the steering column). I remember one guy rolled back, panicked and dumped the clutch. Will always remember the sound of the axle snapping.

Pierce

Re: Can We Have A Manual Down-Shifting Discussion?

Reply #26 – August 06, 2020, 09:19:14 pm

First RV-- 1958 VW panel truck. Double clutch or CRUNCH.

Re: Can We Have A Manual Down-Shifting Discussion?

Reply #27 – August 06, 2020, 10:08:22 pm

Quote from: wolfe10 – August 06, 2020, 09:19:14 pm

First RV-- 1958 VW panel truck. Double clutch or CRUNCH.

Split case tranny and 6 volt I bet.

I also had one but a PU. It was 6 volts but I converted it to 12v except for the starter. Started instantly after that. I broke the crankshaft but could barely tell. I could grab the generator pulley and the crank pulley would turn a few thousands. No other damage done and a new crank did the trick. I finally put a twin port 1600 in with a Zenith 2 barrel and tunnel trans. The right side behind the cab folded down so you could push a dirt bike up the ramp and then lift the door up. Great truck.

Pierce

Re: Can We Have A Manual Down-Shifting Discussion?

Reply #28 – August 06, 2020, 10:18:39 pm

Learned on my first, 5 forward gears and a 3 speed transfer and yes you better double clutch or you ain't going into the next gear!
This was on a 30 ton Lorain! Fun in town!

Re: Can We Have A Manual Down-Shifting Discussion?

Reply #29 – August 06, 2020, 10:43:45 pm

Quote from: juicesqueezer – August 06, 2020, 10:18:39 pm

Learned on my first, 5 forward gears and a 3 speed transfer and yes you better double clutch or you ain't going into the next gear!
This was on a 30 ton Lorain! Fun in town!

Nice to know that there is more talent on the forum than junk bond Barons who can't change a light bulb or drive a Porsche because the ignition key is on the left side!

Pierce

Re: Can We Have A Manual Down-Shifting Discussion?

Reply #30 – August 06, 2020, 10:43:59 pm

Learned how to drive hauling a dump trailer with a B1 Mack with a triplex. Graduated to an R model 237 Mack and a 5 speed. Never used the clutch while shifting, of course the 5 speed Mack you could take a nap between gears. Rolling black coal from a single stack Mack😎👍

Hey Joe don't get both boxes in neutral at the same time 😬

Re: Can We Have A Manual Down-Shifting Discussion?

Reply #31 – August 07, 2020, 04:52:43 am

My only double clutching was a u-haul truck about 50 years ago. Had some success downshifting.

Re: Can We Have A Manual Down-Shifting Discussion?

Reply #32 – August 07, 2020, 08:20:18 am

Early in our ownership I learned that manual shifting is our friend...thanks to Brett Wolfe.

I routinely use manual downshifting to 5th to maintain RPM when approaching a grade since, at highway speeds, we'll always be in 6th gear on the flat. Since we typically run cruise control on the highway this manual downshift requires no change in throttle position...shifts down, and then up, are smooth.

When cruise if off I will let off the throttle before downshifting and even if I may be heading for 4th gear...or even 3rd on steep inclines, I'll make each shift deliberately with time for the engine to reach the new RPM. The key is to downshift BEFORE the incline so the RPM rise is manageable rather than trying to go down more than 1 gear in a hurry.

I especially enjoy downshifting to 5th through tunnels and along freeway embankments just to enjoy our resonator!

Re: Can We Have A Manual Down-Shifting Discussion?

Reply #33 – August 07, 2020, 09:53:18 am

I manually shift the transmission quite a bit. If I'm in town I'll usually run the correct gear for the speed limit so the trans doesn't continually hunt between gears.

Re: Can We Have A Manual Down-Shifting Discussion?

Reply #34 – August 07, 2020, 10:20:26 am

Outside of California I tend to run with my cruise control set at 65mpg. This is the Max towing speed for my toad. In hilly country I drop it to 5th to reduce speed up on down grades. I'd rather not use the retarder and have my cruise drop out. If I see a more serious downgrade coming, I'll get my speed under 60mph and drop it into 4th, limiting my engine speed to 2200rpm, below the overrun limit on my isl400. If it hits 2500 the warning tone sounds.

Re: Can We Have A Manual Down-Shifting Discussion?

Reply #35 – August 07, 2020, 10:37:48 am

To WildBil

Yes when over revving the transmission will upshift. Corrected my post.

Roland

Re: Can We Have A Manual Down-Shifting Discussion?

Reply #36 – August 07, 2020, 10:39:12 am

Quote from: Tom Lang – August 07, 2020, 10:20:26 am

If I see a more serious downgrade coming, I'll get my speed under 60mph and drop it into 4th, limiting my engine speed to 2200rpm, below the overrun limit on my isl400. If it hits 2500 the warning tone sounds.

I have been led to believe that the Allison brain will trigger a upshift to prevent engine overspeed, regardless of what gear is manually selected. Have you ever observed this behavior from your transmission? Just looking for comments from more experienced owners, like yourself.

I have not personally tested this assertion. I don't ever let our C8.3 exceed 2450 (governor break rpm) - "Better safe than sorry".

Re: Can We Have A Manual Down-Shifting Discussion?

Reply #37 – August 07, 2020, 11:09:38 am

The ECU fuel cutoff on our Detroit is 2130 rpm and in 3rd gear on downgrades. I decided to try it and let it go to 2300 rpm. I never shifted. It might have but then again, it might not have.

I also remember a forum Cummins that bent pushrods, had it repaired, drove further and ruined the engine. Think that one was over revving on a downgrade. Otherwise, you can't bend a pushrod.

Bottom line is I'm not going to take a chance with the Allison.

Pierce

Re: Can We Have A Manual Down-Shifting Discussion?

Reply #38 – August 07, 2020, 11:51:15 am

I hardly ever let things get over 2000 RPM

Re: Can We Have A Manual Down-Shifting Discussion?

Reply #39 – August 07, 2020, 12:02:55 pm

Quote from: bbeane – August 07, 2020, 11:51:15 am

I hardly ever let things get over 2000 RPM

Yes, but you have a retarder. I only push the limit when using our exhaust brake. It works best at high (2400) RPM.

Re: Can We Have A Manual Down-Shifting Discussion?

Reply #40 – August 07, 2020, 12:08:58 pm

Different engines have different RPM limits. Usually, the larger the displacement, the lower the maximum RPM.

Pierce

Re: Can We Have A Manual Down-Shifting Discussion?

Reply #41 – August 07, 2020, 12:23:01 pm

I can remember testing the Allison in the early 90s. Driving a Ford 700 with a manual trans my left knee was starting to have problems ( clutch ) so I mentioned to the supervisor that the next new truck needed to be an automatic. He was very hesitant because the company didn't think an auto would hold up. They ordered one anyway and I never gave that transmission any mercy,, couldn't cause that route ended at 10:00 pm and I needed to get-er-done. Stick it drive and smash the throttle. That truck or transmission never gave me a bit of grief. It held up to anything I ask of it..... but that company also had excellent service policies.
And the truck was propane.

Re: Can We Have A Manual Down-Shifting Discussion?

Reply #42 – August 07, 2020, 01:03:26 pm

Quote from: Chuck & Jeannie – August 07, 2020, 10:39:12 am

I have been led to believe that the Allison brain will trigger a upshift to prevent engine overspeed, regardless of what gear is manually selected. Have you ever observed this behavior from your transmission? Just looking for comments from more experienced owners, like yourself.

I have not personally tested this assertion. I don't ever let our C8.3 exceed 2450 (governor break rpm) - "Better safe than sorry".

I haven't checked in years, but believe my isl400 is ok to 2700-3000rpm in overrun (foot off the gas pedal). Somewhere in that range it will automatically upshift. I've never tested it. But the alarm sounds at 2500rpm. When that happens I hit the service brake and also retarder if cool enough.

Re: Can We Have A Manual Down-Shifting Discussion?

Reply #43 – August 07, 2020, 01:27:56 pm

For another 2003 ISL 400. Serial number: 46210160:

Peak Torque 1200 lb-ft @1300RPM.
Peak HP 2100.
Governed RPM 2330.
Overspeed 2600.

Re: Can We Have A Manual Down-Shifting Discussion?

Reply #44 – August 07, 2020, 01:59:06 pm

Quote from: Roland Begin – August 07, 2020, 10:37:48 am

To WildBil
Yes when over revving the transmission will upshift. Corrected my post.
Roland

I know you knew it, must have been the spell check.

I am looking forward to getting on the road to try my new setup. I have a real engine brake now. on my ISM.
Bill

Re: Can We Have A Manual Down-Shifting Discussion?

Reply #45 – August 07, 2020, 02:39:43 pm

Owned 3 cars, van and pickup with no synchro in first gear. All were three on a tree.

Re: Can We Have A Manual Down-Shifting Discussion?

Reply #46 – August 07, 2020, 08:15:11 pm

Quote from: Realmccoy – August 07, 2020, 02:39:43 pm

Owned 3 cars, van and pickup with no synchro in first gear. All were three on a tree.

Are you sure it was no syncro in first? I drove an old '50s two ton truck with syncro only in first, you had to "double clutch" between all the other gears.

Re: Can We Have A Manual Down-Shifting Discussion?

Reply #47 – August 07, 2020, 09:26:08 pm

Quote from: Pierce & Gaylie Stewart – August 06, 2020, 07:03:40 pm

Does anyone here remember double clutching?

Pierce

Rode shotgun with my Dad as a toddler watching him double clutch his International flatbed. He had a brick and stone business in Western New York, I couldn't wait until my legs were long enough to reach the pedals. Set me up for a lifelong yearning to push on a go pedal and see the countryside...

Re: Can We Have A Manual Down-Shifting Discussion?

Reply #48 – August 08, 2020, 10:22:06 am

These hills in Vermont have been giving my coach a workout for sure. I have mostly left it up to Allison to manage the gearing, but will try more manual shifting options heading up to Maine and see how that works out. I only use economy when its pretty flat. The retarder is getting a good workout on these roads.

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