$200+ to switch speedo in transmission swap

[jd21476]

I had my T350 tranny swapped out to a 700R4. I have 4.10 gears and a 350 motor and my speedo is now showing about 90MPH when I'm cruising at about 70MPH. I ordered some new gear for the speedo but the tranny shop told me that they were the wrong gears and I had to get an in-line adapter. I called a local speedo shop and he told me it would be around $200ish to get the adapter nad fit it on the truck. This seems awefully expensive.

Anyone else deal with this issue?

[gchemist]

Go here: Scroll down to GM Ratio Adapter
http://www.transmissioncenter.org/70...List.htm#Gears

[jd21476]

That looks like it will work and the price is reasonable. Now I just need to call them to see which one I need.

[54Caddy]

You can swap the plastic gears for the speedo in the transmission it's what I did.

[jd21476]

Originally Posted by 54Caddy

You can swap the plastic gears for the speedo in the transmission it's what I did.

I tried that and the shop that did my tranny said I ordered the wrong gears cause they are not on the tranny.

[84chevyguyid]

I went on Bowtie Overdrive and they had a chart that you input your tire size, and axle ratio and it told you what gear you should have in the trans and what gear for the speedo drive out. Its easy to pull the tail housing and install or change the output shaft gear then match it with the right driven gear and your speedo should be pretty close.

[rudey737]

I've never done the swap, but a quick google/youtube search shows that 84chevyguyid is right. Here's a youtube video on how easy the gear swap is.

700R4 Speedometer Gear | Curt's Corner at Monster...

[gchemist]

He has a 4X4. The speedo adaptor is in the engine bay. He can't swap gears down at the tailshaft.

[rudey737]

I totally ignored the 4x4 bit. Pay no attention to me.

[jd21476]

Originally Posted by gchemist

He has a 4X4. The speedo adaptor is in the engine bay. He can't swap gears down at the tailshaft.

Thats right....I forgot what he said exactly but thats is why the gears I ordered wont fit.

[legendman]

Or you could get one of these...



Speedo gear ratio adapter

http://www.gaugeguys.com/speedcorrect.htm

[Irish1941]

Originally Posted by gchemist

He has a 4X4. The speedo adaptor is in the engine bay. He can't swap gears down at the tailshaft.

Sure he can. You swap at the t-case not the trans. on 4WD. It swaps as easy as a 700R4 2wd. T-case replaces the tail shaft so that's where the plastic gears are.
First - what transfer case to you have behind the 700r4?
203, 205, 208, 241? 700R4 is 27 spline output so I'm leaning towards 203, 208 or 241. The 700R4 to 205 requires fancy ($$$) adaptor.
Anyway, not sure what yrs you are dealing with but that's where the change for speedo ratio is. It drives off the main shaft of the transfer case. You need to figure out what you got vs what you need.
There is only a few color combos.
Pull out the cable from the transfer case and look inside. It can only be one of four colors. Blue, gray, red or yellow. 15 to 19 teeth.
Now look at the gear on the cable. Runs from 37 to 40 teeth then 41 to 45.
All by color.
Post up what color you have inside and on the cable and I can help figure what you need.
You can use an adaptor for ease of install but couple of seals & $30 in gears vs $200 adaptor. You'll still need to look inside so you can get the right ratio. adaptor

[midnight rambler]

did you get the speed o working right ? mines 10 off i need to do it to.

[jd21476]

I did buy the part and went to install it. It turns out there was already a speedo adapter in place and I just removed it and installed the stock cable. It now seems to run close to normal. I dont want to install the adapter that I bought because it is a reducer and will reduce it 27.5%.

I'm sort of upset at the shop cause they never mentioned that there was a speedo adapter already in place and unfortuantely I did not check before ordering the part.

[parrisc19844x4_468]

Originally Posted by Irish1941

Sure he can. You swap at the t-case not the trans. on 4WD. It swaps as easy as a 700R4 2wd. T-case replaces the tail shaft so that's where the plastic gears are.
First - what transfer case to you have behind the 700r4?
203, 205, 208, 241? 700R4 is 27 spline output so I'm leaning towards 203, 208 or 241. The 700R4 to 205 requires fancy ($$$) adaptor.
Anyway, not sure what yrs you are dealing with but that's where the change for speedo ratio is. It drives off the main shaft of the transfer case. You need to figure out what you got vs what you need.
There is only a few color combos.
Pull out the cable from the transfer case and look inside. It can only be one of four colors. Blue, gray, red or yellow. 15 to 19 teeth.
Now look at the gear on the cable. Runs from 37 to 40 teeth then 41 to 45.
All by color.
Post up what color you have inside and on the cable and I can help figure what you need.
You can use an adaptor for ease of install but couple of seals & $30 in gears vs $200 adaptor. You'll still need to look inside so you can get the right ratio. adaptor

Hi Irish, I have the same setup , not sure of the transfer case I looks to be a 208 C , my old gear were 243's I now have 391''s. My speedo also shows 90mph when I am only going 70. I could not get the over off to see what the colours where, I can do that this weekend.
the label on the transfer case says Model 208 C.

[parrisc19844x4_468]

Typeo in my privous post, my gears are 3.73