TR2/3/3A 4:1 Diff in a TR3?

[karls59tr]

What affect on acceleration would there be by installing a 4:1 Gear set in the TR3 Diff non-overdrive?

 

[trrdster2000]

Karl , if you are going to use it for AutoX, then great, if you are going to drive it for pleasure, forget it. You will be running a very high RPM at normal highway speed and really high on the interstate. My roadster is a 455 and it restricts me from driving to car shows on the interstate in the summer, I'm just in the way unfortunately.

Wayne

 

[TR3driver]

The change in acceleration isn't as much as you'd think anyway. Too much torque wasted accelerating the flywheel, and lower gears just mean more goes into the flywheel. Steve Hedke made some careful measurements with "Scrappy", the TR3 he built to run in the History Channel's Great Race, and reported that he actually got better acceleration with 3.45 gears! That was with a stock engine, flywheel, tires etc. though. Still, I'm planning to go the same way even with a warmed-over engine, alloy flywheel and low profile tires.

Going from 4.1 to 3.7 did make it harder to spin the rear wheels. Probably a Good Thing, as it is still possible around here to get a ticket for "unsafe start".

 

[charleyf]

I have a friend with an overdrive who swapped out his 4:1 for a 3.7 and really loved the difference. For myself, I changed out my 3.7 for 3.45 in my two TR4s. We drive together a lot and when he had the 4.1 gears he would go up the steeper hills a lot easier than me. But on the downhill side I would be on his tail in a matter of seconds.
To me for all around driving the higher the gears the better. These engines have so much power it is a real waste to put low rear end gears in them unless it is just for auto crossing. One example that I use is that when I take off from a stop light behind my friend, he is shifting into second gear before he gets to the pedestrian crossing on the far side of the intersection, I am still in first gear and right on his tail.
Charley:fat: