Speedo Reading 20mph high

[1KWIKSIX]

Recently installed one of Lonnies Stg II L/UP transmissions in my car that I bought used from another member. I had Lonnie freshen it up & install a billet forward drum, etc before I installed it.
Previous owner had it installed in a mid 80's Camaro/Firebird behind a 350 cu in motor.

I find I'm getting whacky speedo readings in my Buick.....I'd guess it's reading about 20mph higher than the actual cars speed.

My best guess is that the Camaro had different rear end gearing & therefore this tranny has different speedo drive gears.

I do have my original 200-4R BRF tranny handy so could swap out speedo gears if it isn't a big job?

Can anyone familiar with this type of work on these tranny's please let me know what colour gears should be installed for the 342 gear set in the rear end & the steps involved in doing this.

Thanks Much

dave

 

[Pronto]

http://www.transmissioncenter.net/speedometer_calibration_______va.htm
Don't know if they are available.

 

[1KWIKSIX]

Thanks for the link Pronto!

 

[SSedan64]

For 3.42 Gear & stock size Tire:
29-tooth Green Driven gear & 11-tooth Orange Drive gear.
Driven gear is easy, located in outer Bullet/Housing.
Drive gear is inside Pan under cover at rear of Trans.



GM #8634965 11-th Orange

GM #403999 29-th Green
http://chevellestuff.net/tech/speedo.htm

 

[1KWIKSIX]

For 3.42 Gear & stock size Tire:
29-tooth Green Driven gear & 11-tooth Orange Drive gear.
Driven gear is easy, located in outer Bullet/Housing.
Drive gear is inside Pan under cover at rear of Trans.

View attachment 196836View attachment 196837View attachment 196838

GM #8634965 11-th Orange

GM #403999 29-th Green
http://chevellestuff.net/tech/speedo.htm

Thanks very much.
Hmmmm........Since I'm running 16" GTA rims wondering if the above still holds true?

I've got BF Goodrich G Force Sports 255/50ZR16 which are 26.063" diameter?

 

[SSedan64]

Those are the stock equivalent to the factory 215/65/15's so, no noticeable difference.
Comparison >> http://www.gnttype.org/techarea/suspension/Tirechart2.html

Easy Speedo gear calculator >> http://www.montess.org/speedo_gears.html

The Driven gear Bullet/Housing can be a pain to remove if you're in a cold, snowy area, road salt etc.. helps corrode it + they're dissimilar metals. I suggest spraying several times with penetrating oil & using Vise Grips, Channel Locks etc.. with something covering the jaws to protect the Speedo Bullet threads from damage. Twist back & forth to loosen & twist/pull out.

 

[TR Custom Parts]

For 3.42 Gear & stock size Tire:
29-tooth Green Driven gear & 11-tooth Orange Drive gear.
Driven gear is easy, located in outer Bullet/Housing.
Drive gear is inside Pan under cover at rear of Trans.

View attachment 196836View attachment 196837View attachment 196838

GM #8634965 11-th Orange

GM #403999 29-th Green
http://chevellestuff.net/tech/speedo.htm

Great info!

 

[David Husek]

Recently installed one of Lonnies Stg II L/UP transmissions in my car that I bought used from another member. I had Lonnie freshen it up & install a billet forward drum, etc before I installed it.
Previous owner had it installed in a mid 80's Camaro/Firebird behind a 350 cu in motor.

I find I'm getting whacky speedo readings in my Buick.....I'd guess it's reading about 20mph higher than the actual cars speed.

My best guess is that the Camaro had different rear end gearing & therefore this tranny has different speedo drive gears.

I do have my original 200-4R BRF tranny handy so could swap out speedo gears if it isn't a big job?

Can anyone familiar with this type of work on these tranny's please let me know what colour gears should be installed for the 342 gear set in the rear end & the steps involved in doing this.

Thanks Much

dave

A stock BR-F trans is calibrated for a 3.42 gear ratio. The parts installed are 11 teeth (orange) drive gear and 30 teeth (blue) driven gear. The orange drive gear will be in the pan towards the back of the trans. Drain the fluid and remove pan. Remove the 4 - 13mm bolts and remove cover and governor assembly. (See picture posted above by SSedan64) You will need to remove the old drive gear from the governor assembly. It is held on with a c-clip. After its removal, pull off the washer then the old drive gear and replace with the new orange drive gear, washer and replace the c-clip. The driven gear is located on the outside of the trans, drivers side rear. Remove the speedometer cable, then the 10mm bolt and bracket that holds the driven gear bullet assembly in the case. Slide driven gear bullet assembly out of case. Slide old driven gear out of the bullet and replace with the new blue driven gear. Slide driven gear back in bullet. (See picture posted above by SSedan64) Reinstall driven gear bullet assembly using a new o-ring on the bullet housing. Use trans fluid on o-ring and case bore, then push bullet assembly back into case. Reinstall bracket, the 10mm bolt and then the speedometer cable. Place governor back in cover, use a new gasket on cover and slide assembly back into the case. Reinstall the 4 bolts and torque them to 200 inch pounds. Reinstall pan with new gasket and fill with fluid... Hope this helps...

 

[1KWIKSIX]

Thank you David, for a very thorough & helpful write up & also a big thank you to SSedan64 & Pronto too. You guys have all been a big help to not only me, but to others who may face a similar project one day. Don't know what people would do if not for the likes of you all + the many other members who regularly step up to the plate to help the needy (like me) with their knowledge & expertise.
Hey David, if I can't find the speedo bullet "O" ring & the governor cover gasket locally.....can I purchase these from you?

Thanks much.

dave

 

[David Husek]

Hey David, if I can't find the speedo bullet "O" ring & the governor cover gasket locally.....can I purchase these from you?

Thanks much.

dave

I have plenty of them in stock, just give me a call when you are ready....

 

[1KWIKSIX]

Sent you a PM

thx

dave

 

[GNRick]

My VDO speedometer has always read about 20 mph too fast. I also have 255X50X16's in back. I have the stock orange and blue gears, 3.42 rear end. Art Carr has a speedometer adaptor on his website for $75. He says if you compare your speed from your gauge with actual speed per gps, he will calibrate the adaptor. Does this sound like an easy fix?

 

[1KWIKSIX]

Hey Rick,

My Mechanical VDO speedo was pretty close when using my original transmission.
S0, I pulled the pan on my EA Stage II tranny & found a red (12 tooth drive gear ) & a black (27 tooth driven gear).
Guess that would explain the whacky speedo reading. You gotta understand that I bought this transmission used form another member who had it in a late model Camaro/Firebird & I dropped it off to Lonnie to freshen up & install some parts. Didn't even think about the different rear end in the car & the speedo gearing.

So, I swapped out the speedo gears for the original ones in my spare BRF tranny that came out earlier this summer.
The orange (11 tooth drive gear) and (green 29 tooth driven gear) seems to have got it fixed close enough for me.
Checking with my GPS yesterday at speeds up to 75mph & I am now only 1 -2 mph out, which I can live with.

Now I've just gotta sort out why my 3rd gear pressure switch is indicating open on my PL at all times. Have changed to a known good 3rd gear pressure switch outta my BRF but it still reads open. These are a normally closed switch.
Guessing that there is a short somewhere. Not sure if it could be in the pan or from the wiring up to the ECM. Gonna check to see if it could be pinched between the tranny housing & firewall? Understand that this is not totally uncommon? If not there, looks like the tranny pan is coming off again for a closer look at the wiring.

Onward & upward!

dave