[Fot] Gear ratio recommendations

[Robert Lang]

 Not to beat a dead horse, but with your setup, the 4.10 would be the best bet. You'll use the 1:1 and the overdrive gears only.
Lime rock "standard" times for small bore production cars, lap average speeds are close to 90 MPH. Sidebar: the track has one of the highest if not the highest average lap speed for any track in the USofA. The slowest corner on the track is the exit of Big Bend and if you get the line perfect, you're at 65 to 70 MPH. The left hander is a tosser, so don't even try to gear for that. The most critical corner is West Bend because you carry that "Mo" all the way to the entry to Big Bend.
I'll also +1 the tire diameter - I assume 23" - 24" diameter tires with a nod towards 24". Smaller than that, you need the 3.70, for sure.
Regards,Bob Lang
    On Monday, March 24, 2025 at 11:59:39 PM EDT, Dave Riddle via Fot <fot at autox.team.net> wrote:  
 
  
While we will be running the Toyota 5 speed in the TR4 at Lime Rock that gear box and engine are slated to go back in the BajaTR3 afterwards.  The motor that is being built for the TR4 is being mated to a 4-speed TR4 box that has been order.  Trying to determine what gear ratios to run in it.  Will have both a 3.71 and 4.11 final drive and the motor turning over at 6k with about 175 hp at the rear wheels.
 
  
 
Currently the Toyota boxes we have are running…
 
  
 
1st           3.950                    3.830
 
2nd          2.140                    2.060
 
3rd           1.38                       1.430
 
4th           1.00                       1.00
 
5th           0.810                    0.840
 
  
 
Anyone care to share the hot setup for a 4-speed TR4 box?
 
  
 

 
Dave Riddle
 
Business IT Consulting
 
Office: 480.610.8234
 
Cell: 602.692.5276
 
eMail: dave at microworks.net
 
Website: http://www.microworks.net
 

 
  
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