TH 400 Speedo Gear

[Steven B.]

Which speedo gear is correct for a TH 400 with 4.11? I don't have sources with me.

Thanks!

Steve

[Tom L.]

Re: TH 400 Speedo Gear

Steve, I went through this a while back and bougt a few gears before I got the right one. The way I found out is that the gear holder (for lack of a better word) listed the possible gears that would fit in the "holder". I don't remember what the "holder" said, and I can't see it in the car, but the gear I bought for a 3.08 was a TM-168 (a ZIP cataloge #). Hope this helps and Have fun!!

[Joe L.]

Re: TH 400 Speedo Gear

Which speedo gear is correct for a TH 400 with 4.11? I don't have sources with me.

Thanks!

Steve

Steve-------


Assuming you're talking about a car with typical C3 stock tire size and assuming that you have one of the more common speedometer DRIVE gears installed in the transmission, I don't think you can do this without an adapter.

[Richard G.]

Re: TH 400 Speedo Gear

To determine the correct speedometer gears for your application, use the following formula to calculate to calculate the number of teeth on the driven gear (round to the nearest available gear.
# DRIVE TEETH X AXLE RATIO X TIRE REV PER MILE
-------------------------------------------
1

= NUMBER OF DRIVEN TEETH


If failed to note if these numbers were for a 400 or 350 style gear but here they are:

Driven Gear Color Part Number 34T Lt Green 9774413 35T Orange 25522477 36T White 25522479 37T Red 1359271 38T Blue 1359272 39T Brown 25522485 40T Black 25522487 41T Yellow 25522489 42T Green 25522491 43T Purple 25522493 44T Dk. Gray 25522495 45T Lt. Blue 9775187

May be as clear as mud as this forum doesn't take formulas well. Contact me off site and I can email you the excel sheet.