third member switch

Joined
Apr 23, 2005
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Location
marietta, GA
Im plannin on puttin 33's on my 79 and want some 4:11 gears. Is trading third members with someone the best way to get these gears? And how would the lower gears be on the road compared to the 3:70's?

thanks
 
Joined
Aug 11, 2004
Messages
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I'd estimate that your top speed would lower 10-15 mph from the 3.70 thirds. (I can easily cruise below 3k going 70-75 with 3.7's and 31's, but can only hit 60-65 with 4.10's. You'll get more oomph out of your truck (you'll even have to worry about spinning out sometimes) and will be able to go through all of your gears in a short fraction of the time compared to 3.7's... I don't know what the exact compensation of 33's will have, I'd say they tack another 5-10 mph...
 

Gus

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Apr 13, 2003
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Ridgway, CO
Sort of a hi-jack; I've been thinking of doing this to my 79 FJ40, would you have to use fine spline third member diffs out of a 78 FJ40 or FJ62 or could you use the (from what I've heard, weaker) course spline third members providing you switched to course spline axle shafts.
 
Joined
Apr 24, 2003
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i don't think the coarse spline diffs from 76-78 ( i might be wrong) were coarse axles, weren't they coarse pinions?

i don't know... the full floaters are fine spline after 76
 

nuclearlemon

not an addict
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Joined
Jan 30, 2003
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Location
meh-ico, colorado
when you swap, swap slipshafts also, that way neither you or whomever you swap with will have to deal with matching flanges to driveshafts.

i went to 4.11's in my 60 when i went 33s and i'm almost back to stock.
 
Joined
Aug 11, 2004
Messages
24
A '75 I had (as with my newer 40's) was fine axle, it was stock as well. Also, what you can do is just change out the spider gears, right? I thought that only the older FJ40's had course axles?
 

Gus

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Apr 13, 2003
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This sounds easier than I had anticipated, thanks for the clarifying everyone ,
 

PabloCruise

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Jun 3, 2004
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If you can find fine spline pinion thirds from a 62 (4.11), that would be the ticket.

Also, put the front third in the rear, as they have virtually no mileage compared to the rear...
 
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