Does the Seneca have enough power

[mikew968]

On my next unit I would probably choose a Dynaforce 37TS HD with the 8.9L cummins at 350 hp and 1000 lbs feet. 100 gal fuel and 30% T would certainly be welcome.

[jvteach77]

Originally Posted by memphis02

I you have a good pair of binoculars or an average telescope, you can see it from the driver's seat. -It's over near the passenger's side of the dash.

I suspect the switch has been removed on the 2017's. I don't have one on mine.

[Robbbyr]

Originally Posted by jvteach77

I suspect the switch has been removed on the 2017's. I don't have one on mine.

The 2017's have the same engine/transmission combination as earlier models, seems odd Jayco and/or Freightliner would take away the ability to lock out overdrive when appropriate.

Is it incorporated somehow into the shifter, or is it the same as earlier models with PB R N D 3 2 1 ?

[jvteach77]

I'll go out to my RV and look again and really search for a OD lockout, but I don't think it makes sense to remove that function either.

[jvteach77]

I went and searched my dash, shifters, and everywhere else I could think of and I didn't find a switch, button, or any way to cut the overdrive on or off. I looked in the manual that came with my freightliner and there was no mention of an overdrive option.

[Robbbyr]

Very odd. I like having the ability to lock 5th and 6th (the two overdrive ratios in my tranny) out when the road conditions cause it to try to shift too frequently.

I wonder if Allison/Freightliner changed something in the transmission software to keep it from "hunting" which can cause more wear and heat? I wonder if an email to Jayco would shed any light on things.

Inquiring minds want to know!

[jvteach77]

I haven't contacted Jayco yet, but on my drive home with the RV from Grand Rapids to Georgia we went up a few moderate hills that would have had my Greyhawk screaming trying to maintain even 35mph. My seneca was never hunting for a gear that I could tell.

[jvteach77]

Here is the response I got back from Jayco when I asked about the absence of an overdrive cutoff switch in my 2017 Seneca.

Mr. Vandergrift,
Here is what I got back from out Freightliner supplier.
The overdrive lock out switch was removed from the M-2 for the 2017 model year chassis, this was a Freightliner engineer request.
The transmission will shift automatic as needed.

[Robbbyr]

Now we know! Thanks.

Mine will certainly shift automatically when it loses speed and starts to lug, but I glad I have my switch. Loaded down (towing) on certain terrain it wants to shift too much in my opinion, and when it is doing that I can watch the trans fluid temp creep up on my ScanGauge. I limit it to 4th and the temp will quickly drop back to where it was. And I have to think the clutch packs and converter lockup will sustain less wear and tear not engaging and disengaging quite so much. While I probably do lose a little economy, I feel longevity is a good trade-off.

According to the specs of our transmissions, with our engine ratings we are running right at the upper end of the 2500's torque-handling capabilities. I was told this by my Freightliner dealer when we discussed flashing the Cummins ECM to gain more HP and torque. The ISB has more in it, but the transmission would suffer in their opinion. So I am leaving mine alone!

[Mountain Cajun]

I don't notice any difference when my OD switch is on or off. I always wondered if it was even working. I tried to check it and turn it off going up a hill and now difference in shift points. My rpms on flat ground don't change turning it on or off! ???

[Robbbyr]

Originally Posted by Mountain Cajun

I don't notice any difference when my OD switch is on or off. I always wondered if it was even working. I tried to check it and turn it off going up a hill and now difference in shift points. My rpms on flat ground don't change turning it on or off! ???

On flat ground cruising at expressway speeds it is very obvious if I turn the overdrive off. Immediate downshift with corresponding increase in engine RPMs. If you are going so fast that downshifting would cause an engine overspeed, the transmission software will not let it shift immediately. Slow down some and it will then downshift at the correct moment.

If at around 60 mph there is no change in RPMs when you activate the switch, I would strongly suspect something is not working correctly.

[SloPoke]

Learning that they removed the OD switch is a BIG DEAL for me towing an 8,000+Lbs trailer. Especially when coming down steep grades with the exhaust brake on. I want the flexibility to control the downhill speeds when I am in the 50-60 MPH range and want that added braking from the engine.

I also notice a difference in the shift pattern at 4th and 5th when climbing. The shifting with the OD lockout lets the engine RPM up to about 2300 at the shift point, instead of shifting at 2000 and dropping the next range to 1400. A difference of about 15 MPH when getting on the freeway in traffic.

[SloPoke]

We happened to be at CampingWorld on Saturday and decided to walk thru a 2017 Seneca 36FK on the lot.

We found that the Overdrive Switch is indeed GONE... along with a bunch of other features that we have on our 2015 FK. If we were to be looking at another Super C, we would be looking for an older model still sitting on a dealers lot. We really didn't care for the changes.

[Robbbyr]

I would love to know why Jayco and/or Freightliner removed the switch. I hope it wasn't just to save a few bucks! I strongly suspect any dealership salesperson is going to be clueless about the reason. I plan to go to the Cleveland RV show next month, Jayco usually has some senior people present and I will ask them if I can.

A few years ago at the show I asked them why they switched from hydraulic 4-wheel disc brakes to air drum brakes. Was there a shortcoming in the hydraulic brakes? They assured me the hydraulic brakes were absolutely adequate, but the "competition" was offering air brakes and they felt that some customers would be swayed by that. I asked why they didn't "one-up" them (Dynamax) and spec air disc brakes, they said it was a cost issue.

[vanovafan]

Do you Seneca guys know what rear axle ratios are in your rigs?

[Robbbyr]

Originally Posted by vanovafan

Do you Seneca guys know what rear axle ratios are in your rigs?

5.13:1 in my 2014

[vanovafan]

Originally Posted by Robbbyr

5.13:1 in my 2014

Thanks Robbbyr, Can you tell me what your rig weighs in at fully loaded, no trailer. Also, do you 22.5's or 19.5's. Over drive trans or final drive gear 1:1?

Bill

[Robbbyr]

Originally Posted by vanovafan

Thanks Robbbyr, Can you tell me what your rig weighs in at fully loaded, no trailer. Also, do you 22.5's or 19.5's. Over drive trans or final drive gear 1:1?

Bill

Last time I weighed just the rig (no toad) packed for camping and full of water, grandsons, wife and I onboard, we were at 26,400. GVWR of 28K, GCWR 33K. 22.5" tires, Allison 6-speed, 5th and 6th both OD but I can't remember the exact ratios. 4th gear is 1:1.

[vanovafan]

thanks so much for your replies. You are really helping me figure a rear axle ratio issue I'm working on. How does your truck pull up long inclines with the toad on the back. Do you do them in 5th or 4th? thanks again.

Bill

[Robbbyr]

Originally Posted by vanovafan

thanks so much for your replies. You are really helping me figure a rear axle ratio issue I'm working on. How does your truck pull up long inclines with the toad on the back. Do you do them in 5th or 4th? thanks again.

Bill

Somewhat of a long story. Originally my unit came with 340 hp 700 lb/ft torque, and my Allison was (mistakenly) programmed with an "ultra economy" shift schedule. Cummins even had a bulletin regarding performance noting that the mistaken transmission programming could hamper performance. With that original power/shifting combo my unit would slow on the large grades and never shift down to 5th. When it would lug down enough it would drop all the way to 4th (direct drive) but the momentum was lost, never to be regained on the long pulls. My unit has a dash overdrive cancel switch which I would employ and force a downshift to 4th in an attempt to keep a little more momentum. Helped a bit.

But based on feedback from other owners I discovered that I could (for a fee of course) have Cummins "uprate" my horsepower and torque to 360/800. Allison also reprogrammed my transmission to a performance shift schedule. Those two upgrades have significantly changed the way my unit drives. Now on the long upgrades the unit will easily downshift to 5th as I ascend. Unless it is an extremely long/steep grade I will usually be able to maintain my speed towing my Ford Edge ST. So much better than before! Obviously there are still some mountains where I slow to where it drops to 4th and 55-60 mph is what it will maintain at that point.