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  #1  
Old 02-12-2014, 02:17 PM
Harrdware
 
Join Date: Sep 2012
Location: near Winchester, VA
Posts: 18
W114 / W115 Rear axle ratio

Greetings,

Just revived a 1969 model 230-6 gas car with automatic), daily driver, and started driving it around.

The car shifts through all 4 gears quickly, then about screams to 3750 rpm or higher, at highway speeds. It seems have enough power, but is extremely noisy. Not used to those kind of revs just to keep up with traffic on highways. Reminds me of my old muscle car days. My wife says shift it into 5th gear! I say, there is no 5th gear, it's 4 and done!

I saw the data card lists an axle #030847. What axle ratio is this? Maybe 3:91? Are there other, lower numeric, axles that could be swapped in, to bring the revs down? Acceleration is more than fine, I could give up a bit, to keep the overall revs down, which will help with long-term engine wear, and better gas mileage.

I imagine there are overdrives available, like for the US muscle cars, but they are $2K or more. On a budget here. A axle swap would fit the budget better. Any ideas? Thanks,

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  #2  
Old 02-12-2014, 02:34 PM
Registered User
 
Join Date: May 2010
Posts: 860
The later 114/115 cars had a 3.69 differential instead of your 3.92--I'm not sure whether they're interchangeable with earlier cars, or if the driveshaft setup is the same.

One alternative I've used with all my 114's is to change the back tires to the tallest set I could find--say 205/75/14 or 215/75/14. This lowered the ratio by 7-8% and helped compensate for the usually optimistic VDO speedometers



Tim Kraakevik
kraakevik@voyager.net
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  #3  
Old 02-12-2014, 07:40 PM
Harrdware
 
Join Date: Sep 2012
Location: near Winchester, VA
Posts: 18
Thanks for your thoughts. I know you have lots of experience with the /8s, esp. the later ones. I will research the later diff. swap. Do you happen to have any from the parts cars you had?
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  #4  
Old 02-12-2014, 09:39 PM
Registered User
 
Join Date: Feb 2011
Location: Modesto CA
Posts: 4,068
Harrdware:

Center sections (aka, diffs) interchange physically between models 114/115, 123, 116 w/ inline engines, and 126 w/ inline engines.
The ring gear of all of these is 185mm in diameter.
Ratios range from 2.88:1 to 4.36:1.
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  #5  
Old 02-12-2014, 11:45 PM
Registered User
 
Join Date: Apr 2009
Location: Los Angeles (Altadena)
Posts: 1,923
Quote:
Originally Posted by Harrdware View Post
The car shifts through all 4 gears quickly, then about screams to 3750 rpm or higher, at highway speeds. It seems have enough power, but is extremely noisy.
3750 RPM on the highway is normal. Is there a bad noise, or is it just that you feel the engine should rev lower (as many people feel)? You can change the axle ratio by swapping the rear end, or as the previous poster says, use taller tires. Both of these will change the speedometer reading to read less than before, whether or not that is an improvement is up to you. If you have a smart phone you can download an app called SpeedView (for Android, I'm sure there is something similar for iPhone) and see if your speedometer is way off from actual speed.
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  #6  
Old 02-13-2014, 02:09 PM
Registered User
 
Join Date: May 2010
Posts: 860
I don't have differential parts--email sent



Tim Kraakevik
kraakevik@voyager.net

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