Inliners International
Posted By: straight axle 63 Gear Change - 02/09/14 04:55 PM
OK now that I have the cam choice done (comp 260) I think I may be in need of gear change. Right now the rear gear a 2.41 7.5" axle from a 78 El Camino. The trans is a Saginaw 4 speed with the following ratios 3.5, 2,47, 1.65 and 1:1. With a 4500-5000 projected shift points I will have 39-44mph in first, 55-61 second and 83-92 in third. The 60 mph cruise rpm is about 1950.

I do not want to loose any street drivability but also want to be able to get out of the hole quickly ( I do some 1/8 mile drags) I was thinking on 3.23 or 3.42. Right now my tire size is 205/60 15. I can change to a taller tire if needed too, maybe a 205/70 or 205/75. Oh yeah the car is a 1962 Chevy II
Posted By: intergrated j 78 Re: Gear Change - 02/09/14 11:48 PM
If you went with a 3.42 gear it would be almost like driving down the road in 3rd gear now. 2.41x1.65=3.9765. If you wanted to kinda see what it would be like put on some 235/75/15 and head to the nearest freeway in third gear. If I had your combination I think 3.08 would be the best combo for not loosing driveability but going quicker in the 1/8 mile.What speeds is the car going at the end of the track? 5000 Rpm in third gear would be about 73mph 4500 would be about 66mph in third with a 3.08 axle and 24.9 inch tall tire. With a 60 mph cruise rpm being~2500rpm. A lot would depend on what gears you can get cheap and easy. After all some fine tuning can be done with tire height. I am sure other people will post up with their ideas. Jay 6155
Posted By: straight axle 63 Re: Gear Change - 02/10/14 01:43 AM
My only time at the track I had really bad traction, and spun the fist 70 feet or so, I am shooting for 70 at the traps. I have no freeways around me, and only have about 15 minutes on one on the way to the track.
Posted By: CNC-Dude #5585 Re: Gear Change - 02/10/14 02:33 AM
Keep in mind that Saginaw's aren't real strong trannys, they were put in a lot of Vega's, Monza's and low HP 4 cylinder vehicles. And in a heavy car like this may be troublesome.
Posted By: Beater of the Pack Re: Gear Change - 02/10/14 03:26 AM
I abused one in my '53 pickup behind a pretty stout 270 for years with no problem. Put in a T 5 and gave the Saginaw to a young friend for his small block powered Model A. He blew it up almost immediately.
Posted By: straight axle 63 Re: Gear Change - 02/10/14 11:53 AM
If it does go I'll replace it with this.
http://www.jegs.com/i/Richmond-Gear/836/1304000071/10002/-1?parentProductId=

I all ready have a Hurst competition shifter.
Posted By: intergrated j 78 Re: Gear Change - 02/10/14 09:47 PM
If 70mph is the goal,then 3.08 will get you there. If you make more HP than you think with the "260" cam then put on a little taller tire. That will decrease rpms at the end of the track. So will the T-10 with its different 3rd gear. At this point 4th gear becomes a poor mans overdrive to get you to the track. My understanding with the sag 4spd is it is real weak in reverse. I don't have any experence with this trans. Jay 6155
Posted By: straight axle 63 Re: Gear Change - 02/11/14 12:52 AM
Poor mans overdrive is exactly why I went with the trans. I can use all three gears instead of two with a th350, and still drive at highway speeds! I do not know much about them, all I know is mine works great and only cost me $200 with proper ChevyII bellhousing! I wonder if a T5 is stronger???
Posted By: intergrated j 78 Re: Gear Change - 02/11/14 09:30 PM
Sadly, I can't help there either. All I know about T5s is that there are different ones out there with different ratios. There is also something called "world class", I don't know (but would like to learn) what that means. I used to own an 89 Chevy 1/2 ton pickup with a 5 speed that was nice I just don't know who made the trans. Jay 6155
Posted By: Beater of the Pack Re: Gear Change - 02/11/14 11:01 PM
There is a good chart in our "Tech Tips" section that shows T5 ratios and applications. There are also several ratios to choose from in the Saginaw. Also Patricks sells a modified Hurst shifter that moves the stick forward into a much better place. His catalog shows the Saginaw ratios but the online catalog page is hard to read. PATRICK'S
Posted By: CNC-Dude #5585 Re: Gear Change - 02/11/14 11:29 PM
 Originally Posted By: straight axle 63
Poor mans overdrive is exactly why I went with the trans. I can use all three gears instead of two with a th350, and still drive at highway speeds! I do not know much about them, all I know is mine works great and only cost me $200 with proper ChevyII bellhousing! I wonder if a T5 is stronger???

Pretty mild 5.0 Mustangs can break a T5 without a lot of effort and they only weigh 3000-3200 lbs., an El Camino is a lot heavier and probably can break them just as easily if driven hard. A good adjustable PP can go a long way toward softening the shock of dumping the clutch though.
Posted By: straight axle 63 Re: Gear Change - 02/12/14 01:55 AM
The axle is out of a El Camino, the car is a 62 Nova that weighs about 3000 with me in it and a full tank of gas.
Posted By: CNC-Dude #5585 Re: Gear Change - 02/12/14 01:57 AM
Ok gotcha, I mistook your car as the El Camino and not the rear end.
Posted By: straight axle 63 Re: Gear Change - 02/12/14 08:36 PM
It was one of those free and was the correct width deals. Little more work but worth it.
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