No Park Gear Selection on Motorhome Trannies??? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Huskerboy2 · 02-03-2006, 12:57 AM

Probably a stupid question, but what's the deal on motorhome trannies. I picked up my new '68 motorhome today. It has a TH400 and there isn't a park. There isn't even a P on the gear selector. I looked at some pics I have of other motorhomes from this era and they are the same. No park. These things sit in neutral with a big hand brake. I never realized this. It completely sucks because my storage space is on a little bit of a slope and the hand brake aint so great. What's the reason for this and is there a conversion or modification that can be done?

Fred T · 02-03-2006, 02:13 AM

The reason was part breakage and strength. The pawl system used on the th400 was not strong enough to take the weight of the truck. Best solution I know of is to chock the wheels and keep the hand brake functional. If you had air brakes you could put spring cylinders on the rear, but I'm assuming you have hydraulics.

**Bob B.** · 02-03-2006, 05:00 AM

For the same reason most Allison automatics in large trucks and buses don't have 'Park' either.

Longhorn Man · 02-03-2006, 06:15 AM

torque lock is the other reason for this.
You ever parked on an incline, and then couldn't get the car out of park later? The weight of the vehicle would lock it into park.
No park, no problem.

I know in the army hummers, the tranny has park... but the shifter doesn't. Disconnect yout linkage, and see if you can put it in park. If so, then a column swap is all that is needed.

**special-K** · 02-03-2006, 07:45 AM

The pawl is missing in the 30 series TH400.These were the first automatics put in 1tons and,for all the reasons provided,it was believed to be too much to ask from "park" on a bigger truck:don`t give the option,it can`t be used.On my`70 C/30,I installed a line-lock in the hydraulics.Mine was a Winnebago chassis-mount before I got it.It`s pretty rare to find an automatic C/30 cab`n`chassis that didn`t start life as an RV.

Huskerboy2 · 02-03-2006, 10:45 AM

Thanks for the replies. That all makes sense. Pretty much what I figured. I was thinking that if I parked this thing on a hill, I wouldn't be able to get it out of park anyway. I guess I just never noticed before that these things didn't have park. There have been a couple of times when I have looked at interior pics of these rigs and they looked like they were in gear? I guess that explains it.

Sorry for the ignorance on trannys. I've never dealt with them much. Is the pawl in the column? So, a column swap could remedy the issue? I'm going to a flatbed with this thing and after my 200 mile drive from Fort Worth, my 6'6" 275lb. body is telling me to put in a tilt as well.

OLDCHEV4X4 · 02-03-2006, 10:53 AM

The pawl is in the transmission.

02-03-2006, 12:57 AM	#1
Huskerboy2 Senior Member Join Date: Feb 2001 Location: Austin, Texas, USA Posts: 1,628	No Park Gear Selection on Motorhome Trannies??? Probably a stupid question, but what's the deal on motorhome trannies. I picked up my new '68 motorhome today. It has a TH400 and there isn't a park. There isn't even a P on the gear selector. I looked at some pics I have of other motorhomes from this era and they are the same. No park. These things sit in neutral with a big hand brake. I never realized this. It completely sucks because my storage space is on a little bit of a slope and the hand brake aint so great. What's the reason for this and is there a conversion or modification that can be done? __________________ '72 Chevy Blazer

02-03-2006, 02:13 AM	#2
Fred T Cantankerous Geezer Join Date: Aug 2002 Location: Bel Aire, KS Posts: 6,264	Re: No Park Gear Selection on Motorhome Trannies??? The reason was part breakage and strength. The pawl system used on the th400 was not strong enough to take the weight of the truck. Best solution I know of is to chock the wheels and keep the hand brake functional. If you had air brakes you could put spring cylinders on the rear, but I'm assuming you have hydraulics. __________________ Fred There is no such thing as too much cam...just not enough engine.

02-03-2006, 05:00 AM	#3
Bob B. Senior Member Join Date: Aug 2005 Location: Los Angeles Posts: 1,316	Re: No Park Gear Selection on Motorhome Trannies??? For the same reason most Allison automatics in large trucks and buses don't have 'Park' either. __________________ 1967 GMC CM-2500 Camper Cruiser, 351E V-6, NP 435 4 speed, Dana 60, and factory A/C. 2012 GMC K-3500 WT regular cab, 6.0L Vortec, 6L90.

02-03-2006, 06:15 AM	#4
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Re: No Park Gear Selection on Motorhome Trannies??? torque lock is the other reason for this. You ever parked on an incline, and then couldn't get the car out of park later? The weight of the vehicle would lock it into park. No park, no problem. I know in the army hummers, the tranny has park... but the shifter doesn't. Disconnect yout linkage, and see if you can put it in park. If so, then a column swap is all that is needed.

02-03-2006, 07:45 AM	#5
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,862	Re: No Park Gear Selection on Motorhome Trannies??? The pawl is missing in the 30 series TH400.These were the first automatics put in 1tons and,for all the reasons provided,it was believed to be too much to ask from "park" on a bigger truck:don`t give the option,it can`t be used.On my`70 C/30,I installed a line-lock in the hydraulics.Mine was a Winnebago chassis-mount before I got it.It`s pretty rare to find an automatic C/30 cab`n`chassis that didn`t start life as an RV. __________________ "BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~

02-03-2006, 10:45 AM	#6
Huskerboy2 Senior Member Join Date: Feb 2001 Location: Austin, Texas, USA Posts: 1,628	Re: No Park Gear Selection on Motorhome Trannies??? Thanks for the replies. That all makes sense. Pretty much what I figured. I was thinking that if I parked this thing on a hill, I wouldn't be able to get it out of park anyway. I guess I just never noticed before that these things didn't have park. There have been a couple of times when I have looked at interior pics of these rigs and they looked like they were in gear? I guess that explains it. Sorry for the ignorance on trannys. I've never dealt with them much. Is the pawl in the column? So, a column swap could remedy the issue? I'm going to a flatbed with this thing and after my 200 mile drive from Fort Worth, my 6'6" 275lb. body is telling me to put in a tilt as well. __________________ '72 Chevy Blazer

02-03-2006, 10:53 AM	#7
OLDCHEV4X4 Registered User Join Date: Apr 2000 Location: Chester County PA, USA Posts: 1,228	Re: No Park Gear Selection on Motorhome Trannies??? The pawl is in the transmission. __________________ 72 k/10 short wideside 72 k/5 Blazer 72 K/5 Blazer - obstacle course racer 72 custom/10 8' bed 70 K/5 Blazer 67 C-30 GMC Flat bed 86 GMC K2500 Plow Truck 85 GMC K3500 84 M1008 85 M1008 77 G30 Motor Home 72 Sears 12hp Tractor Glenmoore, Pennsylvania



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