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Old 04-25-2016, 05:38 PM
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TH350 vs TH400...... Whats the difference?

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Old 11-23-2001, 03:00 PM   #1
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Default TH350 vs TH400...... Whats the difference?

I have noticed that a lot more people with 10 second or lower LS1's are moving to a 3 speed auto. But there seems to be a mix of TH350's and TH400's. What is the differences between the two? Can a 350 hold 800+ rwhp?

- Matt
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Old 11-23-2001, 03:40 PM   #2
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Default Re: TH350 vs TH400...... Whats the difference?

The TH350 is a lighter transmission that can built just about as strong as a TH400 (some say JUST AS strong.)

800 RWHP? It will but not forever. That's alot of power!
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Old 11-23-2001, 03:48 PM   #3
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Default Re: TH350 vs TH400...... Whats the difference?

TH350 is lighter, and takes less power to spin, but it wont last as long.

I'd say 1st gear is different, but I dont know how much. If you look hard enough you can find a TH350 with lock-up also, which will help retain some streetability over a TH400. I believe one of the 9.50 or faster LT1s has a lockup TH350. They were used in vans and some pickups weren't they?

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Old 11-23-2001, 04:16 PM   #4
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Default Re: TH350 vs TH400...... Whats the difference?

Who sells a th 350 for our cars? Do our converters work with them(probably not, huh)?

Marty

[ November 23, 2001: Message edited by: Marty ]</p>
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Old 11-23-2001, 04:32 PM   #5
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Default Re: TH350 vs TH400...... Whats the difference?

TH400's were orginally so strong that GM decided the quality had to reduced because they lasted too long and held up too well. TH400 250,000 miles + was pretty common. TH400 was designed to hold up behind a Big Block with lots of torque.

A properly built TH400 can have a fair amount of weight reduction with careful selection of parts and this can help it be more effficent.

Not taking anything away from the TH350...but with massive torque I'd look at TH400's with updates very closely.
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Old 11-23-2001, 05:11 PM   #6
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Default Re: TH350 vs TH400...... Whats the difference?

350 saps less power

gears for anyone that wants them (standard planetary)

350 - 2.52 1.52 1.00
400 - 2.48 1.48 1.00
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Old 11-23-2001, 08:59 PM   #7
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Default Re: TH350 vs TH400...... Whats the difference?

What kind of selection is there for gears?
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Old 11-23-2001, 11:25 PM   #8
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Default Re: TH350 vs TH400...... Whats the difference?

At what rwhp would you folks consider stepping up from a 350 to a 400?

- Matt
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Old 11-24-2001, 12:16 AM   #9
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Default Re: TH350 vs TH400...... Whats the difference?

THERE are many different gear ratios avail, for these tranzs, but are big dollars($500-$700over the standard price)when i switched over from my 700r4 to a th-400 i thought i would suffer in the 60 ft area because of the gear change(3.06to a 2.4)first gear- the car stayed in the same 60#s as before picked up about .05 in the 1/4 but lost 2 mph over the 700r4 i was satisfied with the stock gears in the th400, so if you want to change gears in one of these tranz, you might spend the $ in a better area
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Old 11-24-2001, 02:53 AM   #10
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Default Re: TH350 vs TH400...... Whats the difference?

I have a 2.75 1st gear in my TH350.

As far as the difference in strength between the 350 and the 400...I can't tell you first hand but there are many that swear that a 350 built just right is even stronger than any 400. Don't know, just hearsay. So far my 350 is working perfectly. <img src="images/icons/cool.gif" border="0">
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Old 11-27-2001, 01:35 PM   #11
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Default Re: TH350 vs TH400...... Whats the difference?

Not to worry, The th350 is a very heavy duty tranny. I have also the th350 with all the goodies inside and it seems to be far more a heavy duty light weight tranny and does absorb less power in spin then the th400..(fact)
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Old 11-27-2001, 07:49 PM   #12
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Default Re: TH350 vs TH400...... Whats the difference?

Where could I get either one of these trannies...you never know!
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