Slant Six Forum,  Forum Index
Slant Six Forum,  Forum Index
Slant Six Forum,  Forum Index
Home Slant Six Forum,  Forum Index Log in Register FAQ Memberlist Search

Click here to make a donation to the Slant Six Forum!

Speedo Gear Question
Goto page Previous  1, 2
 
Post new topic   Reply to topic    Slant Six Forum, Forum Index -> Transmission & Rearend
Select message display options:             View previous topic :: View next topic  
Author Message
DusterIdiot
Board Sponsor


Joined: 29 Oct 2002
Posts: 10070
Location: Salem, OR

Post subject: Yep... (Tue Mar 28, 2017 4:08 pm) Reply with quote

Quote:
I checked with Claude and the tire size is 185/70R14. Where do I look up the calculations you guys did?



You need a 35 tooth gear on the nose....

I have an old spreadsheet that does the calc...don't remember where I got it, but it is sure useful.


Back to top
View user's profile Send private message
Chuck
Site Admin


Joined: 12 Oct 2002
Posts: 1382
Location: Grass Valley, Ca.

Post subject: (Tue Mar 28, 2017 6:27 pm) Reply with quote

Thanks Dan!



_________________
Chuck Rivers, Webmaster
Back to top
View user's profile Send private message Visit poster's website
Chuck
Site Admin


Joined: 12 Oct 2002
Posts: 1382
Location: Grass Valley, Ca.

Post subject: (Tue Mar 28, 2017 6:28 pm) Reply with quote

slantzilla wrote:
Will do.


Wink



_________________
Chuck Rivers, Webmaster
Back to top
View user's profile Send private message Visit poster's website
Chuck
Site Admin


Joined: 12 Oct 2002
Posts: 1382
Location: Grass Valley, Ca.

Post subject: Re: Yep... (Wed Mar 29, 2017 9:48 am) Reply with quote

DusterIdiot wrote:
Quote:
I checked with Claude and the tire size is 185/70R14. Where do I look up the calculations you guys did?



You need a 35 tooth gear on the nose....

I have an old spreadsheet that does the calc...don't remember where I got it, but it is sure useful.


Do you also have calcs for the early tranny? I have to adjust my '63 too.



_________________
Chuck Rivers, Webmaster
Back to top
View user's profile Send private message Visit poster's website
DusterIdiot
Board Sponsor


Joined: 29 Oct 2002
Posts: 10070
Location: Salem, OR

Post subject: Nope... (Wed Mar 29, 2017 3:54 pm) Reply with quote

Quote:
Do you also have calcs for the early tranny?


Sorry Chuck, the table was setup only for the late trannies.

Crying or Very sad


Back to top
View user's profile Send private message
FrankRaso
Turbo Slant 6


Joined: 16 Apr 2004
Posts: 629
Location: Stevensville, ON

Post subject: (Thu Mar 30, 2017 6:07 am) Reply with quote

I have some calculations on my Tire Upgrade page. Don't forget to include the rolling diameter correction in your calculations.

Tire Upgrades

Barry's Tire Tech - Tire Dimensions



_________________
1965 Plymouth Barracuda,
225 engine, Quadrajet, & Dutra Duals, 904 Torqueflite, 2.76:1 axle, Addco sway bars
Rods & Relics - Fort Erie, ON / Collector Car Tech
Back to top
View user's profile Send private message Visit poster's website
Killer6
TBI Slant 6


Joined: 19 Mar 2016
Posts: 113
Location: SW PA

Post subject: (Fri Mar 31, 2017 7:25 pm) Reply with quote

Chuck wrote:
Thanks Dan!


Just to make sure this isn't overlooked, the speedo pinion housing is
marked and offset(eccentric) to accommodate the different diameters
needed for the various tooth counts. Make certain you have it indexed
properly for the one You're using!


Back to top
View user's profile Send private message
slantzilla
Board Sponsor & Moderator


Joined: 17 Oct 2002
Posts: 12075
Location: Park Forest, Illinoisy

Post subject: (Sun Apr 02, 2017 10:26 am) Reply with quote

Closest I have is a 33. Crying or Very sad



_________________
Proud supporter of Mike Jeffrey Racing Engines since 1999.
Back to top
View user's profile Send private message Send e-mail
Chuck
Site Admin


Joined: 12 Oct 2002
Posts: 1382
Location: Grass Valley, Ca.

Post subject: (Sun Apr 02, 2017 4:36 pm) Reply with quote

slantzilla wrote:
Closest I have is a 33. Crying or Very sad


Thanks for checking.



_________________
Chuck Rivers, Webmaster
Back to top
View user's profile Send private message Visit poster's website
shadango
EFI Slant 6


Joined: 08 Aug 2016
Posts: 307
Location: Pittsburgh, PA

Post subject: (Thu Apr 20, 2017 9:22 am) Reply with quote

The charts I have seen all look at diameter/tire height, not the numerical tire sizing..... what matters is the actual distance would be the measurement from the exact center of the hub/wheel assembly to the ground.....but suince that is tough to do right, I figured that taking as accurate a measurement from the ground to the top of the tire would get me close enough.

I have seen when shopping for tires that some of the same tire sizes (for example - a 235 60r 15) have different spec'd tire diameters. Just bought a set of 235 60r 15s for our 80 Volare and found that some brands said one thing and another was a half inch different....and there is a difference between what a targeted size should be versus what it actually is when installed and rolling.....so I would never rely on the advertised tire height to do this calculation.

When I re-geared my Barracuda some time back I just used the diameter of the new tire as mounted, sitting on the ground, and used the gear ratio and found the right number of teeth on the chart,.....worked out well.

Worked for me..... about to do the same for the Volare.....

Keep in mind the the chart has overlap to allow for slight difference in diameter ...for instance a 25.1 and 25.6" tire both use a 28 tooth gear with 2.76s.


Back to top
View user's profile Send private message
SlantSixDan
Board Sponsor & Contributor


Joined: 31 Oct 2002
Posts: 24582
Location: North America

Post subject: (Thu Apr 20, 2017 1:22 pm) Reply with quote

shadango wrote:
what matters is the actual distance would be the measurement from the exact center of the hub/wheel assembly to the ground


Yes...

Quote:
when shopping for tires that some of the same tire sizes (for example - a 235 60r 15) have different spec'd tire diameters


Yes, but only a little bit different, and...

Quote:
overlap to allow for slight difference in diameter ...for instance a 25.1 and 25.6" tire both use a 28 tooth gear with 2.76s.


...this is what makes it easiest to just do the calculation based on the numerical tire size. You might be off by a tenth or two, but it doesn't matter because it's going to be less than the difference between two adjacent pinions. Let's use your numbers, a 25.1" versus a 25.6" tire: that's a 2% difference. 28- vs. 29-tooth pinion, that's a 3.5% difference. Or 28 vs. 27-tooth pinion, that's a 3.7% difference. What makes it best to use the numerical tire size is it's very difficult to accurately measure the diameter of the tire by eye with a yardstick or tape measure.



_________________
一期一会
Too many people who were born on third base actually believe they’ve hit a triple.

Back to top
View user's profile Send private message Visit poster's website AIM Address
Greg Ondayko
Supercharged


Joined: 27 Nov 2004
Posts: 4520
Location: IRWIN PA

Post subject: (Thu Apr 20, 2017 1:34 pm) Reply with quote

Keep in mind the tranny end of the gear/speedo cable on an 80 volare is different than your e body.

The outside hole is the same but the clocking afapther and gear is a different design than 67-75 for example...

Fyi.
Compare Late 70's - 80's style:
http://www.brewersperformance.com/proddetail.asp?prod=SP22L&cat=216

To THe Muscle Era Style: 1966-1977ish:
http://www.brewersperformance.com/proddetail.asp?prod=SP26&cat=216



Greg



_________________
Greg Ondayko
69 Dart www.youtube.com/hyperpack

Back to top
View user's profile Send private message Visit poster's website
Select message display options:   
Post new topic   Reply to topic    Slant Six Forum, Forum Index -> Transmission & Rearend All times are GMT - 7 Hours
Goto page Previous  1, 2
Page 2 of 2

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
Go To Slant Six Forum Home

Mopar Ring Member Site
Mopar Ring Member Site



Powered by phpBB © 2001, 2005 phpBB Group
Theme created by Vjacheslav Trushkin, modified by Chuck Rivers