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Author Topic:   Gear ratios for the GM saginaw trans?
rnoswal53
Dirt Maniac

Total posts: 120
posted March 27, 2005 09:21 AM  
What are the gear ratios for this trans mission? As far as I know it is stock. I am trying to figure out the final gear I need to run a 1/4 mile track. Right now the car has a 5.43 gear and I want to top out at around 7000 rpms or so. Any information would be great.

Thanks
Russ

leapinlizard
Dirt Freak

Total posts: 402
posted March 27, 2005 10:10 AM  
High gear or final gear is always 1:1. Unless the trans in qeustion has over drive. Then it's usually 30% over driven or .70:1.

rnoswal53
Dirt Maniac

Total posts: 120
posted March 27, 2005 10:29 AM  
Duh, of course! I didn't even think about that. Thanks. Ok, well how about a rear gear number for a 1/4 mile track, topping out at 7000 rpms or so.

Thanks
Russ

FearDaPierce 35
Dirt Roller

Total posts: 22
posted March 27, 2005 10:50 AM  
Depend on your car weight,hp,track conditions as well as throttle control to...We run a 2500pound 650hp mod on a tight banked 1/4 mile and we run a 514 and turn 7000-7400 tops most all the time

rnoswal53
Dirt Maniac

Total posts: 120
posted March 27, 2005 01:56 PM  
Hmmmmmmm, well the weight is 2400 minimum, horsepower is probably closer to 400/450. Track is red clay that stays fairly tacky and smooth the whole night. Usually there is a lower and upper groove. I have quite a bit of experience in other cars, but this is my first year in modifieds. If you are turning those numbers with a .514, the .543 will add at least 2 to 300 rpms.

Thanks

nut3d
Dirt Freak

Total posts: 331
posted March 27, 2005 05:44 PM  
I ran a fast 1/4 mile last season with my car. 2550 550 hp engine and had a 543 gear and turned 6800 to 7200 so i would say your 43 would work.

uforacing51
Dirt Forum Champ
Total posts: 570
posted March 28, 2005 03:27 PM  
Most saganaw second gears are 1.82 if that is the gear you are running in. if you want to get gears, then run in the 1 to 1 gear.

FlyNLoIMCA17
Dirt Forum Champ
Total posts: 753
posted March 28, 2005 04:50 PM  
The trans. gear ratios can be different for each transmission. I'm not sure if its 1st or 2nd or both thats different but I know that if you look on the input shaft there will be lines running opposite of the shaft splines. some trans. have no lines some 1 or 2 or 3. Thats how you can tell the gear ratios but I can't remember the exact numbers for each one. But 3rd gear is always 1:1.

I run a pretty tight turned 1/4 mile dry track with about 400-500HP. I ran 5.83 gears last year and normally turned around 7600-7800. Now I'm running 5.67's but my tach is messed up and I don't know what its turning. But 5.67 is basically what most cars in my area are running and almost all the tracks around here are 1/4 some are 3/8.

autoshop
Dirt Freak

Total posts: 298
posted March 28, 2005 07:50 PM  
just of the top of my head I know of 2 different ratios for second gear one is 1.68 to 1 and the other is 1.50 to 1 the tird one i would have to look up at work.

FlyNLoIMCA17
Dirt Forum Champ
Total posts: 753
posted March 29, 2005 12:25 AM  
Ok I finally found it. Here you go!

3-Speed Saginaw

1st 2nd 3rd

No Lines- 2.85 1.68 1.00

1 line- 2.54 1.50 1.00

2 lines- 3.11 1.84 1.00

3 lines- 3.50 1.89 1.00

Those are the lines or grooves that run opposite of the splines on the input shaft.

Hope that helps!!!

Dale

rnoswal53
Dirt Maniac

Total posts: 120
posted March 29, 2005 07:31 AM  
That helps a bunch! Thanks again Dale.

Russ

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