So I just got my jeep regeared to 4.88 and now the speedometer is off which is to be expected. The question I have is kind of an odd one, I originally had 3.07s in the jeep at which time the speedo was off. When I put in Rubi axles with 4.10s and my 35" MTK/Kevlar the speedo was surprisingly spot on. Now I don't know what I have for a speedo gear in the jeep now (its a 97 sport TJ with 6cyl) but its likely I had a 31 tooth gear in. Its "Recommended" that I use a 39 tooth gear for the speedo gear but unless I had a 33 gear speedo in there before Im not sure a 39 tooth gear will make things right...
Anyone running 35" MTRs with 4.88s out there that can comment? Im not sure the Goodyear are a true 35" and i don't want to waste 40 bucks on the wrong gear.... (i know about the give a speedo take a speedo on JF but it doesnt seem there are many folks leaving the higher tooth count speedos).....
1970 Jeepster- stock
2003 Jeep Rubicon 2" BDS Spring lift 35s and MCE fenders
2012 Jeep JKU 2.5' Terafkex spring lift, Rock Hard Bumpa, skids, BodyArmor4x4 sliders..
Jeff : I have a 56 tooth gear in mine with 35s. It really depends on the final drive more than anything else. I went from a three speed to a 4 speed tranny and from a d-20 to a d-300. With 32s.I had 3.73s and my speedo was slow because of the 32s.Now on 35 with 4.56s I keep breaking the cable as the speedo is off the charts ! So I pulled the 39 and went to a56, Ill let you know how close it is. I was told there is more to it than your axle ratio. One of the off road mags had a great explanation. FjR68
Little Napoleon wrote:I have several speedo gears here, believe I have the correct one for you.
that would be great if you do! Let me know Chris!
there is a chart for these things on quadratec and such but I dont know how many teeth my current one has, I only know the speedo shouldnt have been right with 35s and 4.10 given the standard factory tooth count is too low but it was...
1970 Jeepster- stock
2003 Jeep Rubicon 2" BDS Spring lift 35s and MCE fenders
2012 Jeep JKU 2.5' Terafkex spring lift, Rock Hard Bumpa, skids, BodyArmor4x4 sliders..
COH143 wrote:I have 4.56 and 33's soon to be 35's and never corrected the speedo. I use my GPS when on the highway and otherwise don' care. Is that bad?
Your speedo is required to be within 5% of actual speed, or else is a safety violation. Also keeps the odometer accurate.
COH143 wrote:I have 4.56 and 33's soon to be 35's and never corrected the speedo. I use my GPS when on the highway and otherwise don' care. Is that bad?
I think a lot of people do the same thing. I live in a town that strictly enforces the speedlimit and drive thru a few to get to most trail heads so its just better for me to be accurate rather than hoping I remember my GPS. Technically if you dont correct the speedometer the odometer is not accurate and it needs to be disclosed when selling as well as what Jon said...
1970 Jeepster- stock
2003 Jeep Rubicon 2" BDS Spring lift 35s and MCE fenders
2012 Jeep JKU 2.5' Terafkex spring lift, Rock Hard Bumpa, skids, BodyArmor4x4 sliders..