Author Topic: Chevy SM420 manual box  (Read 3485 times)

Ponti

  • Guest
Chevy SM420 manual box
« on: March 27, 2016, 01:25:31 PM »
Has anyone ever used one of these in a slingshot?

ratios are
   1st              2nd                3rd                 4th                 Reverse
7.05 : 1      3.57 : 1         1.70 : 1          1.00 : 1             6.78 : 1

 Wondering about using just 3rd and 4th.

 Any thoughts?

Offline bikeguy307

  • Full Member
  • ***
  • Posts: 241
    • View Profile
Re: Chevy SM420 manual box
« Reply #1 on: March 28, 2016, 05:23:47 AM »
Those are some interesting ratio's. 3rd and 4th are close to some of the glides I have built for my higher HP customers 1.69 and 1.00. Would be interesting if you could remove 1st and 2nd to make it a true 2 speed box.

Ponti

  • Guest
Re: Chevy SM420 manual box
« Reply #2 on: March 29, 2016, 08:36:08 AM »
I'm just toying with idea's.  Will have to look to see how gears are set in the box.

Offline ricardo1967

  • Hero Member
  • *****
  • Posts: 570
    • View Profile
  • Your Best Time: No full pass yet.
  • Your Engine: Alky SBC 400
  • Your Track: Brown County Dragway (Bean Blossom, IN)
  • Your Vehicle: 173" FED
Re: Chevy SM420 manual box
« Reply #3 on: March 29, 2016, 02:23:20 PM »
I like the idea, but I think you're considering what when comparing gear ratios between manual and automatics transmissions, the torque converter provides additional reduction.