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  #1  
Old 05-06-2020, 05:39 PM
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Join Date: Jan 2003
Location: Dallas
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OK to shift to "Park" and tighten tailshaft nut to 120 N.m?

Park pawl looks really robust; I assume I could engage it and torque up the big rear tranny nut without breaking anything?

Tks
DG

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  #2  
Old 05-07-2020, 12:10 PM
ILUVMILS's Avatar
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You should be fine. I imagine the parking pawl sees higher loads when parked on an incline....
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  #3  
Old 05-09-2020, 07:10 AM
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Trevor Hadlington
 
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Location: Worcestershire in England
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I would not do it that way .If you have ever seen whats in the auto box in way of this pawl its not that strong . Anyway i would not do it this way ,the torque is so great on the flange nut ,.Its up to you ,,so if the gearbox plays up after you will know why. The manual wont tell you to do it this way .I would make a fixture from a scafold pole and a good clamp . And another factor is your flexi joints will take all the force ,,so it will do these a world of good .

Last edited by optimusprime; 05-09-2020 at 07:30 AM.
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  #4  
Old 05-09-2020, 08:37 AM
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Quote:
Originally Posted by ILUVMILS View Post
You should be fine. I imagine the parking pawl sees higher loads when parked on an incline....

+1


Quote:
Originally Posted by optimusprime View Post
I would not do it that way .If you have ever seen whats in the auto box in way of this pawl its not that strong . ...

ok lets take a following example:

-mass of the car: 1500kg
-parked on a 30 degree slope
-0.3m tire radius
-3.07 axle ratio


cars weight on earth: 1500kg x 9.81 = 14715 Newtons

force pulling on the car on a 30 deg slope: 14715/2 = 7358 Newtons

torque on the braking wheels from this force: 7358 x 0.3 = 2207 Newton-Meters (Nm)

torque on the driveshaft (tranny output yoke) = 2207 / 3.07 = 719 Nm


So as you see torquing the nut to only 120 Nm is not a problem because the parking pawl is designed for a lot more torque.

719 Nm is just to hold the car in place. When you put the car in park while slightly rolling the peak forces are way higher than that

Last edited by Usaguy; 05-09-2020 at 09:18 AM.
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  #5  
Old 05-10-2020, 03:30 PM
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Join Date: Jan 2003
Location: Dallas
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Thanks for the info.
Yeah, the park ratchet looks like it could hold a ton easily.
However, with the trans sitting on the work bench it was pretty easy to jam the rear tripod with a socket and lock it up; so I went ahead and used that method.
All is good, assuming I fixed the shifting problem I tore it down to resolve, and I got all 17 possible leak points well sealed. Wish me luck!

DG
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  #6  
Old 05-12-2020, 01:39 PM
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Good analysis Christuna, especially about the forces involved with shifting into park while still rolling.

Fun fact: At a 45% gradient (25 degrees), Waipio Rd. in Honokaa, HI is the steepest road in the USA. Here are the top ten: https://cdn.fixr.com/infographics/top-10-US-steepest-streets-1.jpg

Baxter Street here in Los Angeles is a real eye opener to first-timers when Waze routes them around freeway traffic, lol. Waze really shouldn't use Baxter.
https://editorial01.shutterstock.com/wm-preview-1500/9689883a/4ee71eb6/steep-street-los-angeles-usa-shutterstock-editorial-9689883a.jpg
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Last edited by URO Parts Support; 05-14-2020 at 12:19 PM.
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  #7  
Old 05-14-2020, 12:07 PM
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Quote:
Originally Posted by URO Parts Support View Post
Fun fact: At a 45% gradient (25 degrees), Waipio Rd. in Honokaa, HI is the steepest road in the USA. Here are the top ten: https://cdn.fixr.com/infographics/top-10-US-steepest-streets-1.jpg

nice infographic

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