700r4 speedo problem, any tranny experts here??? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**John Fabris** · 05-09-2006, 08:16 PM

Hi All,

I am running a 700r4 tranny (with mech speedo), and I am using a B&M Lockup control that connects inline of the speedo cable to the back of speedometer. On the tranny, there is two plastic gears, one on final drive shaft of the tranny, and one that is on the side (of which the speedo cable goes into).

My problem is that the gear for cable, when placed into the tranny housing, does not engage the shaft gear. (meaning you can spin the gear in the housing and it is not meshing with the shaft gear).

What is the problem? Has anyone seen this before? I will ask my tranny shop Wed evening when I pass by them on way home from work, but just checking to see if anyone here knows what is going on.

this is keeping me from driving this truck (for fear of hurting the tranny do to the lockup control not being activated).

Gordo · 05-09-2006, 09:29 PM

There is a large range of ratio possiblities. No one drive gear will match all possible driven gears and vise-versa. A good trans shop/tech or GM parts counter person would have the resources to supply you with the correct gear combo. Bring with you your tire size, rear end gear ratio and transmission ID#.

**Boog** · 05-09-2006, 10:21 PM

I can't help you with the speedo John but I have to say that is one smooth short for sure. Great color, trim, sits right and good wheel & tire sizing. Good choice on the engine, tranny and rear gearing too for a driver.

Chevrolet4x4s · 05-09-2006, 10:31 PM

Awesome Truck
Shane

BubbaGreen · 05-09-2006, 10:33 PM

Check out this site and pay attention to the 700R4 section for gears and
a subnote about the "inserts" below the table. GM makes two different housings. Make sure you are using the correct housing.

http://www.tciauto.com/tech_info/speedo_gears.htm
http://www.tciauto.com/components/speedometer_gears.htm

PS: awesome looking truck you have put together!!!

**John Fabris** · 05-09-2006, 10:41 PM

I do have a correct set of gears for my application, but did not know that there are two gear housing.

That maybe what is happing with my set up, Thanks Bubba for that link!!!

Thanks to all for the comments about my truck, I have more pictures, I just need to resize all of them for the web page and I will post more here!!

13lazer · 05-10-2006, 01:58 AM

i attempted to install the identical lockup controller you are using. it was an awkward box i couldnt mount and the 2 plugs on the bottom didnt hold the electical connectors in contact very well.
the housing on the rear of the tranny was a hassle, and the plastic gear mounted on your output shaft can slip. if it's more than 1/4" too far in or out, your gears might not mesh. you will not hurt your tranny running without lockup engaged. the throttle valve adjustment will kill your tranny, running without your torque converter locked up might cause some extra heat on a long run. there are several links that explain how to wire the lockup solenoid through a relay, your brake light switch, and a toggle switch.
i took a hammer to that b&m module for all the time i wasted trying to make it work right.
oh yeah, the speedo gear adapter was fun. i used a deburring bit in the tail housing and a beltsander on the gear adapter and shaped them enough to stop the severe leak i had. with a little silicone sealant it hasn't leaked a spot in about 4 months.
i hope there is some info in there that helps you. after all the hassle i went through, i am very satisfied with the end result. i think the only setup i would rather have is a six speed on the floor.

05-09-2006, 08:16 PM	#1
John Fabris TOTY 2006 Join Date: Dec 1999 Location: Magalia CA USA Posts: 2,270	700r4 speedo problem, any tranny experts here??? Hi All, I am running a 700r4 tranny (with mech speedo), and I am using a B&M Lockup control that connects inline of the speedo cable to the back of speedometer. On the tranny, there is two plastic gears, one on final drive shaft of the tranny, and one that is on the side (of which the speedo cable goes into). My problem is that the gear for cable, when placed into the tranny housing, does not engage the shaft gear. (meaning you can spin the gear in the housing and it is not meshing with the shaft gear). What is the problem? Has anyone seen this before? I will ask my tranny shop Wed evening when I pass by them on way home from work, but just checking to see if anyone here knows what is going on. this is keeping me from driving this truck (for fear of hurting the tranny do to the lockup control not being activated). __________________ John Fabris 67 C10 SWB

05-09-2006, 09:29 PM	#2
Gordo Registered User Join Date: Jan 2001 Location: Killingworth, CT. USA Posts: 3,378	Re: 700r4 speedo problem, any tranny experts here??? There is a large range of ratio possiblities. No one drive gear will match all possible driven gears and vise-versa. A good trans shop/tech or GM parts counter person would have the resources to supply you with the correct gear combo. Bring with you your tire size, rear end gear ratio and transmission ID#. __________________ 1971 C10 swb stepside 350/700R4/3.73posi (retired as of 4/22/03) 1998 S10 short bed 2002 S10 Blazer 1942 Oldsmobile 1958 Massey Harris Pony 1951 Wife Killingworth, Connecticut May those who love us, love us, any of those who do not love us, may God turn their hearts. And if God is unable to turn their hearts, may he turn their ankles so we may know them by their limping. A man who works with his hands is a laborer; a man who works with his hands and his brain is a craftsman; but a man who works with his hands and his brain and his heart is an artist.

05-09-2006, 10:21 PM	#3
Boog laying low Join Date: Mar 2001 Location: Searcy, Ark. USA Posts: 13,514	Re: 700r4 speedo problem, any tranny experts here??? I can't help you with the speedo John but I have to say that is one smooth short for sure. Great color, trim, sits right and good wheel & tire sizing. Good choice on the engine, tranny and rear gearing too for a driver. __________________ Boog 69 Chevy stepside, 358/T350, 4.11 posi, 4.5/4 drop, rallys, poboy driver primer is finer 91 Chevy sportside, Tahoe, Yukon & GMC Crewcab All GM..'nuff said. I stand for the flag and kneel at the cross

05-09-2006, 10:31 PM	#4
Chevrolet4x4s Registered User Join Date: Nov 2005 Location: WV Posts: 227	Re: 700r4 speedo problem, any tranny experts here??? Awesome Truck Shane __________________ 1993 K1500 350 5 speed 1985 K10 Silverado Vortec 406 5 speed (in body shop) "I been drivin' this '85 pickup truck Them buddies of mine call it a bucket of rust She's a little beat up but she still runs like the wind Yeah, kinda like me I been banged and bruisedBeen around the block a time or two But I'm runnin' like new goin' places I never been No, I ain't broke I'm just broken in" 1963 Dodge Townwagon(its amazng what 30 years and zero miles will do to a vehicle ) Member#20327

05-09-2006, 10:33 PM	#5
BubbaGreen Senior Member Join Date: Mar 2001 Location: Cedar Park, TX Posts: 686	Re: 700r4 speedo problem, any tranny experts here??? Check out this site and pay attention to the 700R4 section for gears and a subnote about the "inserts" below the table. GM makes two different housings. Make sure you are using the correct housing. http://www.tciauto.com/tech_info/speedo_gears.htm http://www.tciauto.com/components/speedometer_gears.htm PS: awesome looking truck you have put together!!! __________________ 71 Chevy C-10 SWB Fleetside RamJet-350/4L60e & Compushift/3.73Posi See it at www.prismnet.com/~grzanich Last edited by BubbaGreen; 05-09-2006 at 11:26 PM.

05-09-2006, 10:41 PM	#6
John Fabris TOTY 2006 Join Date: Dec 1999 Location: Magalia CA USA Posts: 2,270	Re: 700r4 speedo problem, any tranny experts here??? I do have a correct set of gears for my application, but did not know that there are two gear housing. That maybe what is happing with my set up, Thanks Bubba for that link!!! Thanks to all for the comments about my truck, I have more pictures, I just need to resize all of them for the web page and I will post more here!! __________________ John Fabris 67 C10 SWB Last edited by John Fabris; 05-09-2006 at 11:38 PM.

05-10-2006, 01:58 AM	#7
13lazer 13lazers' blazers Join Date: Jul 2005 Location: San Pedro, CA Posts: 152	Re: 700r4 speedo problem, any tranny experts here??? i attempted to install the identical lockup controller you are using. it was an awkward box i couldnt mount and the 2 plugs on the bottom didnt hold the electical connectors in contact very well. the housing on the rear of the tranny was a hassle, and the plastic gear mounted on your output shaft can slip. if it's more than 1/4" too far in or out, your gears might not mesh. you will not hurt your tranny running without lockup engaged. the throttle valve adjustment will kill your tranny, running without your torque converter locked up might cause some extra heat on a long run. there are several links that explain how to wire the lockup solenoid through a relay, your brake light switch, and a toggle switch. i took a hammer to that b&m module for all the time i wasted trying to make it work right. oh yeah, the speedo gear adapter was fun. i used a deburring bit in the tail housing and a beltsander on the gear adapter and shaped them enough to stop the severe leak i had. with a little silicone sealant it hasn't leaked a spot in about 4 months. i hope there is some info in there that helps you. after all the hassle i went through, i am very satisfied with the end result. i think the only setup i would rather have is a six speed on the floor. Attached Images __________________ 1970 2wd blazer 1972 1ton blazer 4x4 in progress 1966 mustang coupe (modified) 1985 c20 suburban tow rig 1996 462 ranger with a 150 efi merc. a former B.A.S.S. tournament boat almost all exempt from california smog laws intentionally.

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