How fast am I going????????

Nate Dogg · 09-22-2004, 04:20 PM

OK, I bought a CJ7 with 35's and there is no way that the speedo is right. I am getting to around 45 or 50 on the speedo and that is as fast as I feel comfortable.

Any idea how fast that really is?

390fastback · 09-22-2004, 04:40 PM

Assuming you originally had 235/75/15 and the axel and speedo gear haven't been changed, you are doing around 54-60mph.

Dimension4 · 09-22-2004, 06:13 PM

heh this is funny for me. In the jeep I just bought, an '84 with 30.5"s I asked a cop if he would clock me as I went by and tell me how fast I was going. Instead he told me to follow him and he would go 55. When he was going 55, my speedo read 54. Well, it felt alot faster, so go fig.

CJ-5 · 09-22-2004, 09:20 PM

LMAO.....
I remember my first ride in my CJ-5, no top, no doors, I was always used to driving a full sized vehicle.......WOW did it FEEL fast for the first week....
Now I drive it at 65-70 mph always. You'll get used to it too.

liver156 · 09-22-2004, 11:12 PM

easiest way to figure it out is to use a GPS. that way you can index several speeds to memory. 50 on my CJ-7 is 59 on the GPS, a good thing to know in cop country!

390fastback · 09-23-2004, 08:21 AM

I just figured a rough ratio for increase in circumfrence diference, then used it as a multiplication factor to what ever speed you are doing. A 235/75/15 tire has a circumfrernce of about 89.5 inches, a 35" tire has a circumference of about 110 inches. This works out to a ratio of 1.23 times. If you multiply 45mph by this you get 55mph, and so forth.

**CJ51973** · 09-23-2004, 11:19 AM

Here are some formulas. I'm off about 5 mph at top end (65). It's a ratio so it's less the slower I go.

http://www.offroaders.com/info/tech-corner/reading/mph-rpm.htm

83greencj7 · 09-23-2004, 11:34 AM

You can get a new gear from your CHrysler or Dodge dealer. Some of the gears are no longer available. I got mine right on on the second try. Here are the part numbers.

Teeth Color Part Number
24 WHITE 3410024
25 BLUE 3410025
26 RED 2538926
27 WHITE 52068149
28 BLUE 52068150
29 BLACK 52068151
30 YELLOW 52068152
31 GREEN 52068153
32 BLACK 52068154
33 YELLOW 52068155
34 GREEN 52068156
35 ORANGE 52068157
36 RED 52068158
37 WHITE 52068159
38 BLUE 52068060
39 GREEN 52068061
40 ORANGE 52068062
41 RED 2538941
42 WHITE 2538942
43 BLUE 2538943

**CJ51973** · 09-23-2004, 11:48 AM

My understanding is that this list is for Dana 300s. As far as I can find and am told these are not the same gears for a Dana 20. If he has the stock t'case it should be a Dana 20 (If I remember right he bought a '78 or something close). I would be interested if someone knows of a place to get gears for a Dana 20 or if I'm misinformed about there being a difference between the two. I've been too lazy to pull my speedo gear out and check it.

**CJ51973** · 09-23-2004, 12:00 PM

This might be more the calcultor you'd be looking for. I realize you didn't own the Jeep with stock tires but you could probably guess 30" and go from there.
Again, I would love to be wrong about the Dana 20/Dana 300 not being the same gear thing if anyone knows.

http://www.angelfire.com/ca5/TheDuck/calculators.html

tool · 09-24-2004, 09:58 AM

Quote:

Originally Posted by 83greencj7

You can get a new gear from your CHrysler or Dodge dealer. Some of the gears are no longer available. I got mine right on on the second try. Here are the part numbers.

Teeth Color Part Number
24 WHITE 3410024
25 BLUE 3410025
26 RED 2538926
27 WHITE 52068149
28 BLUE 52068150
29 BLACK 52068151
30 YELLOW 52068152
31 GREEN 52068153
32 BLACK 52068154
33 YELLOW 52068155
34 GREEN 52068156
35 ORANGE 52068157
36 RED 52068158
37 WHITE 52068159
38 BLUE 52068060
39 GREEN 52068061
40 ORANGE 52068062
41 RED 2538941
42 WHITE 2538942
43 BLUE 2538943

As far as these part numbers are concerned. I have 35" tires so does that mean I want the one with 35 teeth, Orange?

09-22-2004, 09:20 PM	#4
CJ-5 Registered User Join Date: Mar 2004 Location: Saskatoon, Sk. Canada Posts: 215 Profile Gallery Classifieds My Jeeps	Lol LMAO..... I remember my first ride in my CJ-5, no top, no doors, I was always used to driving a full sized vehicle.......WOW did it FEEL fast for the first week.... Now I drive it at 65-70 mph always. You'll get used to it too.

09-23-2004, 11:34 AM	#8
83greencj7 Registered User Join Date: Apr 2004 Location: Hanover Pa Posts: 35 Profile Gallery Classifieds My Jeeps	You can get a new gear from your CHrysler or Dodge dealer. Some of the gears are no longer available. I got mine right on on the second try. Here are the part numbers. Teeth Color Part Number 24 WHITE 3410024 25 BLUE 3410025 26 RED 2538926 27 WHITE 52068149 28 BLUE 52068150 29 BLACK 52068151 30 YELLOW 52068152 31 GREEN 52068153 32 BLACK 52068154 33 YELLOW 52068155 34 GREEN 52068156 35 ORANGE 52068157 36 RED 52068158 37 WHITE 52068159 38 BLUE 52068060 39 GREEN 52068061 40 ORANGE 52068062 41 RED 2538941 42 WHITE 2538942 43 BLUE 2538943 __________________ 83 CJ-7, AMC 360, RV CAM, GM FI, AUTO WITH SHIFT KIT, FRONT DANA 44 HP LOCKRIGHT HIGH STEER, REAR CURRIE 9" HP SHAVED AND SPOOLED, 37" PJ DIRT GRIPS, AJ'S BODY FENDERS AND HOOD, WARN HS9500, OBA, BESTOP TOP AND SEATS AND STILL GOING.

09-22-2004, 06:13 PM	#3
Dimension4 Registered User Join Date: Sep 2004 Posts: 158 Profile Gallery Classifieds My Jeeps	heh this is funny for me. In the jeep I just bought, an '84 with 30.5"s I asked a cop if he would clock me as I went by and tell me how fast I was going. Instead he told me to follow him and he would go 55. When he was going 55, my speedo read 54. Well, it felt alot faster, so go fig.

09-22-2004, 11:12 PM	#5
liver156 Registered User Join Date: May 2004 Location: dallas oregon Posts: 127 Profile Gallery Classifieds My Jeeps	easiest way to figure it out is to use a GPS. that way you can index several speeds to memory. 50 on my CJ-7 is 59 on the GPS, a good thing to know in cop country!