TH 350 w/ lockup or 200R4? - Hot Rod Forum : Hotrodders Bulletin Board -- Hot Rod Forum

Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Transmission - Rearend
User Name
lost password?   |   register now

LinkBack Thread Tools
  #1 (permalink)  
Old 10-25-2007, 10:26 AM
Join Date: Nov 2002
Location: Beverly Hills
Posts: 442
Wiki Edits: 0

Thanks: 1
Thanked 0 Times in 0 Posts
TH 350 w/ lockup or 200R4?

For some time I have been considering replacing my perfectly good TH350 with a 200R4 pro tranny to get the 4th gear for improved milage on the highway. The other day I was discussing this idea with a fellow rodder who suggested that I could add a lockup feature to my 350 and achieve the same results. I suppose that is true to some extent. I'm wondering what happens to the ride comfort at highway speed with a lockup. Will the car lurch or shake or vibrate because the dampening effect of th torque converter is eliminated? How does a lockup work? Would an engaged lockup at highway speeds disengage automatically in an emergency situation? What do you suggest or advise?

Reply With Quote Quick reply to this message
Sponsored Links
  #2 (permalink)  
Old 10-25-2007, 10:44 AM
XNTRCI-T's Avatar
AKA Lee in KC
Last photo:
Join Date: Apr 2006
Location: Overland Park, KS
Age: 68
Posts: 530
Wiki Edits: 0

Thanks: 0
Thanked 1 Time in 1 Post
I'm no tranny expert, but I'm pretty sure you can't use a lock-up converter on a non-lock-up tranny. You would need a TH350C tranny. The pressure to apply the lock-up clutch in the converter comes from the transmission and is activated by a solenoid in the tranny.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 10-25-2007, 12:11 PM
curtis73's Avatar
Hates: Liver. Loves: Diesel
Last wiki edit: How to find cheap parts
Last journal entry: Found an LQ9 today
Last photo:
Join Date: Dec 2005
Location: Carlisle, PA
Age: 43
Posts: 5,472
Wiki Edits: 16

Thanks: 31
Thanked 52 Times in 44 Posts
You need to get a later (post 82) th350 to get the lockup. You can put a non-locking converter in a lockup 350, but you can't go the other way like you suggest. Its a whole different thing that is engineered into the later trannys.

There is no lurching or anything different in the operation. The only thing you'll notice is that as you accelerate up through the gears, after you get to third, the converter will lock up. It will almost feel like a tiny extra gear change since the RPMs will drop slightly. It just stops the slipping and directly connects the engine to the tranny.

A torque converter sorta works like a manual clutch that's half engaged. A lock up converter just gives you the added benefit of becoming fully engaged at higher speeds.

The 200-4r is a great tranny, and (if your 350 is a short tail version) the 200-4r is almost a direct bolt-in. Its the same length with the same output shaft, so you don't need to change driveshafts. The tranny mount is further back on the case, so you'll need to move your crossmember back. most GMs of that era have other holes drilled in the frame for just that purpose, but if they don't you can drill it yourself. There is an electrical modification to make to get the converter to lockup, but its a pretty easy swap.

Give us more info... what is the car, engine, current rear gears and tire size? If your th350 is backed with 2.73 gears, you don't need an overdrive as it will just lug the engine too slow.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 10-27-2007, 10:39 PM
BMM BMM is offline
Registered User
Last photo:
Join Date: Jul 2006
Location: Not there
Posts: 605
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
One thing to keep in mind, the cost of buying a new 2004R (In my case, $2000), would take quite awhile to make up in fuel savings. Thinking long term, how often will the car be driven at highway speeds? Id rather have my motor cruising at 1500 rather than 2700.

I have a 2.73 rear gear, with a 2004r, and I dont have any problem with a lugging engine in overdrive. It actually cruised along very nicely.
Reply With Quote Quick reply to this message

Recent Transmission - Rearend posts with photos

Quick Reply

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
Please select your insurance company (Optional)


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
Distributor Tuning and Theory - Part 1 Rick WI Engine 35 04-26-2011 12:38 AM
Port or Full time vacuum cool rockin daddy Engine 129 10-05-2010 03:00 PM
Cam/Lifter Question about Ramjet 350 Jake Harsha Engine 20 07-07-2010 06:22 AM
Bog/Black Smoke on Olds 350 at 3000 rpm JohnTN Engine 4 03-17-2009 11:39 AM
Turbo 350 Lockup Converter Wiring boneyard Buick Transmission - Rearend 0 07-14-2005 06:03 PM

All times are GMT -6. The time now is 07:24 PM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999 - 2012. All Rights Reserved.