3.73-A4 RPM at 60MPH??? DD

**SKULLZ** · 09-05-2007, 09:40 AM

Hey hey, I recently had 3.73 gears installed in my 99 Z28. I love them but after reading some gear threads I think my engine RPM is a little too high at 60 mph. Right now at 60 rpm is right at 3000. Does this sound right? I also have a yank 3000 stall, could it be that the TC just isnt locking?? Shift points too high? I don' care so much about mpg, but every little bit helps. I had the work done at a local, reputable shop so I dont think its a shoddy tune. Any words of wisdom from the Ls1 community?? Thanks guys

**2001NBMZ28** · 09-05-2007, 10:17 AM

Something's wrong IMO - according to the calculator at www.f-body.org/gears/ 3.73 gears at 61 MPH should be 2100 RPM. You should be able to feel the TC lock at about 45 unless it's been changed. Bring it back and have them look at it.

**SKULLZ** · 09-05-2007, 10:30 AM

Thanks, I thought it might be a little high.

**firemedic0135** · 09-05-2007, 09:48 PM

yeah I have 3.73 and my tach at 60 is 2000.seems to increase by 400 rpm's every 10 mph

**slims00ls1z28** · 09-06-2007, 09:13 AM

I have 4.11's and 80 is 2800-3000 so ya its off. Sounds like the tq converter is slipping. when you are cruising at this speed/rpm slightly blip the throttle if you feel it move then something else is up if it revs just a hair but doesn't really move its not locking. Definately sounds like its slipping unless you have 13" tires

***Ed Blown Vert*** · 09-06-2007, 09:19 AM

Do you have a cam installed?

**SKULLZ** · 09-06-2007, 10:50 AM

I contacted the shop and they seem to think it is either a wrong gear set (great) or an "improper" tune but more likely the tune. They seem pretty cool and were at least willing to help and fix the problem. No, no cam. I think it may be the TC locking late or not at all.