Trans low gear set.

[Alan Warman]

I run a K/SA Olds with a 307 and Mertic200. How do you know when you need a low gear
set. Mine has a a 2.75 low gear in it now, but they make a 2.91low gear set for it.
So how do you know.
Thanks Alan

[Alan Roehrich]

Things to consider about low gear sets:

1. The lower first gear is, the wider the spread between the gears. Including second and third.

2. Wider spread between gears leads to a greater RPM drop, although that is somewhat mitigated by the stall speed of the converter.

3. Increasing the time you spend at your stall speed in a gear may not lead to greater torque multiplication, or more time at peak torque multiplication.

4. More time slipping the converter can hurt ET and MPH.

5. The lower the gear, the lower the wheel speed is at the shift.

6. Number 5 above can be made worse by the wider spread between gears.

7. All of the above can lead to very poor shift recovery.

8. All of the above can be very hard on engines without a lot of torque and HP.

For a lot of combinations, you reach the point of diminishing returns around 2.75:1.

It is a trade off. One way to tell would be to put more rear gear in the car, and see if it responds with better ET in the 1/8 mile. Then see if it hurts the back half of the 1/4 mile. A rear gear won't cost as much as a low gear set, and might be easier to sell if it does not work. For example, if you're at 5.14 now, try a 5.38. If that doesn't help you in at least the first 330', the low gear set probably won't either.

Remember that when you increase the gear ratio, you're almost certain to have to shift sooner.

You might try one of the ET prediction programs.

[Alan Warman]

Thanks for the info Alan. I was looking for ways to make ny car faster for next year.
Trying to get the biggest bang for the buck.
Thanks Alan

[Alan Roehrich]

I hope that helps you find what is right for your combination. Hopefully, maybe someone with more experience with a combination like yours will step up and point you in the right direction.

[greg fulk]

Alan I have 2.75 low gear in my car with 5.13 & 94" slicks....

[Adger Smith]

Another thing to be aware of is the way a lower gear causes your converter to work like it is tighter. It won't be the same converter when you go lower on gears. The same converter issues happen with rear gear, but not as bad as when you do a low gear tranny set. Some times the converter issues are a good thing and is what actually makes for the combination to be quicker. The lower gear may really help, but the change it causes in the converter may take away any gains. What I'm saying is: Monitor the way your converter works when you change gears. There is more to look at than just an ET Slip!!! That is why it is called getting the most out of your "Combination"