c6 transmission rpm

1987 FORD F-250
150,000 MILES
Avatar
IAN NORDMAN
  • MEMBER
  • 6 POSTS
I have an 87 f250 6.9 idi diesel with a 3 speed c6 transmission. also has sterling rear end with 3.55 gear ratio. does 2400 rpm going 55 mph seem normal with this transmission and gear ratio??? it seems like it is winding engine pretty high and was wondering if this is a normal rpm for 55 mph. any response would be greatly appreciated thank you.
Nov 7, 2011 at 10:44 AM
Advertisement
Avatar
JACOBANDNICKOLAS
  • ✓Experienced Mechanic
  • 110,248 POSTS
That sounds correct. Remember, there is no OD, so the gearing will have a difference at that speed.
Nov 7, 2011 at 10:46 AM
Avatar
IAN NORDMAN
  • MEMBER
  • 6 POSTS
From what i have heard on internet with other owners of same to similer truck, 2,400 rpm at 55mph is correct if equipped with 4.10 gears with c6 transmission. i have double checked my diff gears and they are in fact 3.55. i have 235/85/16 tires which are stock and still manage 2400 rpm at 55 mph. shouldnt rpm be more in the 2,000 rpm range? any available info would be great thanks!
Nov 7, 2011 at 2:39 PM
Avatar
JACOBANDNICKOLAS
  • ✓Experienced Mechanic
  • 110,248 POSTS
I would say it's fine. However, we'll let this post open to see if others respond.
Nov 7, 2011 at 3:09 PM
🔧 Tools & Auto Repair Parts
Find automotive tools, diagnostic equipment, and replacement parts for your next repair.
Shop on Amazon →
Paid affiliate link. As an Amazon Associate, we earn from qualifying purchases.
Add a reply
Join 2CarPros for free, one of the most advanced car repair communities on the internet. From first-time drivers to seasoned mechanics, everyone is welcome to reply, share details, and get better answers. You can add a temporary image or video first; uploads are limited to 20 MB.

Ask a new question

Frequently Asked Problems for This Vehicle