redwake9112

Truck has a 3.55 rear....running 2100 rpms at 60.....this is the truck I swapped trannies on....i know 5spd has a higher ratio in 5th (.79 I think) compared to the auto (.74 I think).....but my speedo is definitely off.....running side by side with my brothers jeep the speedo is of by 8-10 mph. Do I take it to a dealer or a specialty shop or what? thanks. redwake.

Red_Angus

im not sure if this is true about ur dodge, but on the older ones all u have to do is change a gear where the speedo cable connects to the trannie. should be easy to trace. there arent to many lines that connect to the trannie. i think its on the left side, halfway up, mid way back.

NMCTD

if all you changed is the tranny, and you kept your t-case, then the speedo won't be off, speedo is run off the t-case on pre-98 models. However if your running different than stock sized tires (215/85r16) that will cause it to read wrong. What you have to do is change a little plastic gear in the side of the t-case

did you change the t-case?
what size tires do you have (or better yet, just measure the height in inches)?

Get this info for me and I can probably recomend a gear that will get you real close. Otherwise you'll have to take it to a speedo shop to be calibrated.

Just for reference I changed my 4.10 gears to 3.55 gears and I have over sized tires and was able to get my speedo back to withing 2mph at 75 (verified with GPS)

....Josh

OutlawStorm

3.55 rear gears should be running around 1700 rpm at 60 mph not 2100. to me sounds like something isnt right. Are you sure your brothers Jeep is right? I use a GPS to check mine and its close off about 2 mph

Stock size tires will be 245/75/16 on the truck

NMCTD

Not on his truck... Ram 3500 is a dually and had 215/85r16 until 98 year model

OutlawStorm

Sorry missed that,, its a 1 ton dually,, i was thinking a 2500 series.

redwake9112

I did change the t-case.....tires are 235's......the jeep is on the money. I know I am going faster than 60 at 2100rpms....the speedo is just not reading it correctly. thanks for the input thus far. redwake.

NMCTD

235/85r16????

redwake9112

yes....what do you think? redwake

NMCTD

Ok, it will be the same as mine. Unfortunetly there isin't a gear to get it exactly on, but you can get it real close

a 30 tooth will make your speedo read about 2mph fast at 75 meaning if speedo reads 75 you'll actually be going 73.

Here is the dodge part number.... 52067630

you can order the gear at any dodge dealer, or online this is the cheapest place I have found, about $7 per gear http://www.trademotion.com/partlocat...?siteid=213794


Oh yeah and the gear goes in the driver side of the tcase, near the output shaft..... Acutally a google got this how-to for a jeep (same setup as our trucks) http://jeep.us41.org/speedo/index.html


PM me if you have any questions....Josh

redwake9112

aight..thanks man...that helps alot. redwake

NMCTD

glad I could help