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Author Topic:   Is a TH-350 out of a truck geared different?
CrazyT
Dirt Forum Racer

Total posts: 79
posted August 10, 2003 12:53 AM  
I am running a 350 turbo out of a truck in second gear with 3.08 gears. That figures out to be a 4.68 final drive, but i run 7000 rpm on a 4/10 mile track. Everyone else is running like a 5.30 something final drive and barely hitting 6000 rpm. what gives?

racer17j
Dirt Forum Champ
Total posts: 5390
posted August 10, 2003 01:58 AM  
I shift it manually and i am sure it gets into second.

rico 08
Dirt Forum Champ
Total posts: 1139
posted August 10, 2003 08:52 AM  
It's slipping.

racer17j
Dirt Forum Champ
Total posts: 5390
posted August 10, 2003 09:42 AM  
This was kind of embarrasing on my but when I first put my car together for a 3/8 mile track I was sure I had the right gears, but my RPM's were way to high,turns out I had taken the tack out of a v-6 Blazer and forgot to change the setting iside the tack to v-8, went thru alot of work for nothing. Jim

CrazyT
Dirt Forum Racer

Total posts: 79
posted August 10, 2003 11:53 AM  
Man it doesn't feel like it is slipping, the car pulls hard all the way to the corner. I guess i will check the tach again but i don't think that is it. I didn't think the transmission would slip that much and still stay together, and it goes right in gear and shifts good from first to second. I know i have 3.08 because i just had the cover off the rearend and checked it

wizzard
Dirt Freak

Total posts: 306
posted August 10, 2003 08:28 PM  
try a differnet torque conveter just because the trans dont slip mabe the converter is. just a thought

Raz_900
Dirt Forum Champ
Total posts: 635
posted August 11, 2003 10:44 AM  
"stock type" torque convertors will slip ~10%-15%. Some racing units slip less.... like under 5%. Add some clutch slippage (is it a stock high mileage unit?) and 7000rpm could turn into 6000rpm real quick. (7000rpm less 15% slippage = 5950rpm or less 10% slippage = 6300rpm)

Add used/high mileage/stock replacement parts in there and it's very possible bad/worn parts are the problem.

Hutch5375
Dirt Maniac

Total posts: 123
posted August 11, 2003 07:27 PM  
I a rookie, whats the story with the vacuum mod? I haven't dealt much with transmissions...

racer17j
Dirt Forum Champ
Total posts: 5390
posted August 11, 2003 08:03 PM  
I found my problem the tach was set on 6 cylinder. Thanks for all the help

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