700r4 speedo question .....

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

uprdn84

Member
Joined
Mar 3, 2013
Posts
40
Reaction score
2
Location
Gulfport, MS
First Name
Steven
Truck Year
1984
Truck Model
C10
Engine Size
305
Jesus I'm all over this forum asking stupid questions. Why does my speedo cable plug look different than the plug on my tranny? It won't fit. and how can i fix it? Hotrodpc is probably gonna nail me on this.......damn. lol..
 

HotRodPC

Administrator
Staff member
Admin
Joined
Aug 29, 2010
Posts
47,017
Reaction score
9,020
Location
OKC, OK
First Name
HotRod
Truck Year
85 K20 LWB
Truck Model
Silverado
Engine Size
454 - Turbo 400 - 3.73
So you're saying you have a Speedo Cable, but your transmission has an electrical plug in??? If this is true, then you have a mechanical speedo cable, which you should have in an 84, but someone has installed a later model 700r4 from a 90-93 transmission that uses an electronic speedometer and/or Vehicle Speed Sensor (VSS) with a reluctor wheel on the output shaft instead of a plastic speedo drive gear.
 

MrMarty51

Full Access Member
Joined
Oct 25, 2012
Posts
7,512
Reaction score
9,348
Location
Eastern Montana
First Name
Martin
Truck Year
1978
Truck Model
K20
Engine Size
400
So you're saying you have a Speedo Cable, but your transmission has an electrical plug in??? If this is true, then you have a mechanical speedo cable, which you should have in an 84, but someone has installed a later model 700r4 from a 90-93 transmission that uses an electronic speedometer and/or Vehicle Speed Sensor (VSS) with a reluctor wheel on the output shaft instead of a plastic speedo drive gear.
HHHHMMMMmmmm,do I see another TBI conversion a coming ?????:happy175::popcorn:
 

HotRodPC

Administrator
Staff member
Admin
Joined
Aug 29, 2010
Posts
47,017
Reaction score
9,020
Location
OKC, OK
First Name
HotRod
Truck Year
85 K20 LWB
Truck Model
Silverado
Engine Size
454 - Turbo 400 - 3.73
Or just change to an electronic speedo cluster from a 90-91.
 

supercharged

Junior Member
Joined
Jan 2, 2013
Posts
28
Reaction score
3
Location
Cold Lake Alberta
First Name
Steve
Truck Year
1985
Truck Model
c15
Engine Size
350
I ran into the same issue, I pulled the T350 and installed the 700r4 .
The 700 has electronic pickup and t350 is mechanical, was gonna swap tale housing ,but it was a different length ( shorter I believe ) so we would of had to swap output shaft too.
We thought it was a good idea to just stick with the electronic speedo since there is so many variables in actual speed,gear changes tire sizes etc.
I was told if we change the speedo to electronic we could calibrate it a lot easier.
Makes sense if this is true.
 

uprdn84

Member
Joined
Mar 3, 2013
Posts
40
Reaction score
2
Location
Gulfport, MS
First Name
Steven
Truck Year
1984
Truck Model
C10
Engine Size
305
So can i just change out the vss to a gear drive?
 

HotRodPC

Administrator
Staff member
Admin
Joined
Aug 29, 2010
Posts
47,017
Reaction score
9,020
Location
OKC, OK
First Name
HotRod
Truck Year
85 K20 LWB
Truck Model
Silverado
Engine Size
454 - Turbo 400 - 3.73
To change to gear driven, you'd have to pull the trans, and swap out output shafts on the trans too. So yes, it can be done.

And true if ou got all that was needed to do the electonic speedo, they can be calibrated for gear swaps, tire size swaps etc and keep the speedo accurate.
 

MrMarty51

Full Access Member
Joined
Oct 25, 2012
Posts
7,512
Reaction score
9,348
Location
Eastern Montana
First Name
Martin
Truck Year
1978
Truck Model
K20
Engine Size
400
And it makes a good "Platform" to start Your,to TBI swap.:naughty:
 

bucket

Super Moderator
Staff member
Super Moderator
Joined
Aug 3, 2010
Posts
29,150
Reaction score
24,119
Location
Usually not in Ohio
First Name
Andy
Truck Year
'77, '78, '79, '84, '88
Truck Model
K5 thru K30
Engine Size
350-454
To change to gear driven, you'd have to pull the trans, and swap out output shafts on the trans too. So yes, it can be done.

And true if ou got all that was needed to do the electonic speedo, they can be calibrated for gear swaps, tire size swaps etc and keep the speedo accurate.

I thought you could just pull the ring off the shaft and install a speedo gear on a 700r4?
 

HotRodPC

Administrator
Staff member
Admin
Joined
Aug 29, 2010
Posts
47,017
Reaction score
9,020
Location
OKC, OK
First Name
HotRod
Truck Year
85 K20 LWB
Truck Model
Silverado
Engine Size
454 - Turbo 400 - 3.73
I thought you could just pull the ring off the shaft and install a speedo gear on a 700r4?

I know you can swap the gears, BUT, isn't the reluctor built into the output shaft? Don't get me to lying now. It would be great if it was that easy.

Now the 4x4 units, it doesn't matter, and come to think of it, now that I mention 4x4, I think you're right bucket, it's the Tcase output shafts that can't be changed right??? :shrug: Hell, I'm not positive now. Let's research that and find out fo sho. We might come up with some good news.
 

HotRodPC

Administrator
Staff member
Admin
Joined
Aug 29, 2010
Posts
47,017
Reaction score
9,020
Location
OKC, OK
First Name
HotRod
Truck Year
85 K20 LWB
Truck Model
Silverado
Engine Size
454 - Turbo 400 - 3.73
You can, I did it. It's a pain in the ass though.

What do you mean a PITA? Just remove Dshaft and tailshaft housing right? Or do you need a pulled to get the reluctor off?
 

Latest posts

Forum statistics

Threads
42,217
Posts
911,522
Members
33,722
Latest member
schultz76
Top