Screen Removal Bargman L-300 Door Handle brakes Satellite Fuel Tank Fire Extinguishers Roof Antenna Tech Talk Forum Shortcut Motor Oil Window Generators headlights batteries Radiator AC Unit Grab Handle Wiper Blades Wiper Blades Door Locks Door Locks Door Locks Door Locks Rims Front Shocks Rear Shocks Front Tires Oil Filter Steps Roof Vent Awning Propane Tank Mirror Info Clearance Lights Clearance Lights Clearance Lights Clearance Lights Clearance Lights Spartan Chassis Gillig Chassis Freightliner Chassis P-32 Chassis MCC Chassis
    Forums    Tech Talk    Torque Converters
Go to...
Start A New Topic
Search
Notify
Tools
Reply To This Topic
  
Torque Converters
 Login now/Join our community
 
Supporting Member of Barthmobile.com 6/12
Formally known as "Humbojb"
Picture of Jim and Tere
posted
Anyone know if Barth/GM used the RV torque converters in the TH400 trannys they supplied with the big block P30 Barths?


Jim and TereJim and Tere

1985 Regal
29' Chevy 454 P32
8411 3172 29FP3B
Gear Vendor 6 Speed Tranny
 
Posts: 3677 | Location: madisonville tn usa | Member Since: 02-19-2005Reply With QuoteReport This Post
Supporting Member of Barthmobile.com 1/19
Picture of Steve VW
posted Hide Post
The GM chassis that Barth used was a driveaway forward control chassis. I doubt Barth ever changed components on the chassis, with the exception of the tag axles they added to longer models.

The TH400 was built in two variants. The standard units had helical gears. The heavy duty ones (sometimes called the TH475) had straight cut spur gears. They were identical in outer appearance. Some of the heavy duty ones can be identifed by the parking brake drum mounted on the tailpiece.

To my knowlege they all had the same torque convertors.


9708-M0037-37MM-01
"98" Monarch 37
Spartan MM, 6 spd Allison
Cummins 8.3 300 hp
 
Posts: 4197 | Location: Kalkaska, MI | Member Since: 02-04-2011Reply With QuoteReport This Post
Supporting Member of Barthmobile.com 6/12
Formally known as "Humbojb"
Picture of Jim and Tere
posted Hide Post
I've been reading about RV torque converters that lower the stall speed, give a little more oomph off the line, help in slipping and improve fuel economy. Anyone every done this to their TH400?


Jim and TereJim and Tere

1985 Regal
29' Chevy 454 P32
8411 3172 29FP3B
Gear Vendor 6 Speed Tranny
 
Posts: 3677 | Location: madisonville tn usa | Member Since: 02-19-2005Reply With QuoteReport This Post
Supporting Member of Barthmobile.com 1/19
Picture of Steve VW
posted Hide Post
When I replaced the engine on the Regal it went from 240 hp to about 400, also torque around 500lbs/ft.

Stock TH400 is only rated about 500. Since I had the original trans I decided to replace it with something more robust. Competition TH400s are made for over 1000 hp.

I wanted use the 480LE 4 speed with overdrive. Unfortunately they have electronic shifting and require a PCM (Power Control Module) which also interfaces with the modern engines. Unfortunately, my fuel injected 454 had an ECM (Engine Control Module) only. To use the 480 I would have to start over with a PCM and program chips, etc.

Decided to go with a rebuilt TH400 trans. I bought a TCI unit made for RV use, about 800lb/ft rated. A very good unit. Smooth tight shifting, shift rpm allowed engine to pull right to max and not lug down into higher gears.

Getting to the point:

I replaced the torque convertor with the recommended TCI unit. Heavier rating and claims better "lockup" at speed, ie about 4% more efficient.

That seems about correct. At 60mph cruise I was seeing 3000 rpm. With the new torque convertor it was about 100 rpm less.

The tighter shifts were the only thing I noticed when driving
I suspect the gas mileage was up to 4% better but with the numerous changes made I could not prove it.

By the time I sold it, the 33ft tag axle 454HO was getting 8 mpg at 60 mph on the highway. It was getting 6.5 when I bought it.


9708-M0037-37MM-01
"98" Monarch 37
Spartan MM, 6 spd Allison
Cummins 8.3 300 hp
 
Posts: 4197 | Location: Kalkaska, MI | Member Since: 02-04-2011Reply With QuoteReport This Post
  Powered by Social Strata  
 

    Forums    Tech Talk    Torque Converters

This website is dedicated to the Barth Custom Coach, their owners and those who admire this American made, quality crafted, motor coach.
We are committed to the history, preservation and restoration of the Barth Custom Coach.