Stroker kit or re-gear?

R49

R49

Forum odd guy
Lifetime Supporting Member
Joined
Nov 11, 2019
Messages
693
Location
South of Billings MT
2005 X
42rle
Stock gears
4.0
47K miles
So I’ve got my 2022 budget set aside.
Enough $ to install a stroker kit or re-gear but not both. Looking for a bit more power. I’m leaning towards gears but that can get sooo tedious. Rebuilding a low mile engine should be relatively easy but far longer downtime.
Bottom line:
Gears let me take advantage of the 4.0 powerband.
Don’t know if a stroker will provide what I want without re-gear.
Thoughts?
 
What size tires do you currently have, and what is the largest you think you will ever go? I would suspect gearing will make the biggest difference. With only 4 speeds, the autos just can't optimize the RPMs like newer cars with 9 or 10-speed transmissions or manual transmissions with more gears.
 
Richard49 said:
I’ll scour the forum to decide what ratio.
Click to expand...
4.88 or 5.13 depending on your preference. Probably 4.88 if you are certain to go with the stroker.

4.88 on the left. 5.13 on the right. (65,70,80mph)
20211205_193115.jpg
 
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Thanks for the input fellas. I’ll chew on it for a while and let you all know what I decide.
Oh Dana 35 by the way.
Most of my wheeling is above 6000 ft.
 
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I have almost the same setup: sport,2004,4.0,42RLE, stock 3.73 gears.
I am running 245/75R17 with is pretty much identical to your tire (mine 31.5 in inches, yours is 31.7).
I have purchased used Dana 44 (if I would stay with Dana 35 I would go the super 35 path, with better carrier and shafts) and Dana 30 High Pinion (from XJ) with 4.56 gears. Today looking back, I wish I would go to 4.88, or even 5.13. It is true that with 4.56, here in Houston area, that is flat as tile, I would be completely OK, but not ideal. My RPM at 70MPH will be around 2440, which is not ideal. Ideal would be around 2650 ( this is what 4.88 would provide).
Given your altitude I would not think twice and go 4.88. 4.88 will make your life much easier on highways with altitude changes.
Also, my plan for 42RLE is installing Derale transmission cooler (Jerry has the article here, with instructions and part numbers - I am going to execute exactly as Jerry instructed), performing a fluid flush ( BG Quick Clean, will do in my garage), replacing the filter (Mopar filter only) in it, and installing a pan with drain plug. Will be spending almost 500$ for cooler, filter, BG Quick Clean and ATF+4. Also I use Mopar ATF+4 only, not anything else.
As for stroker - without proper gearing, even with stroker you will not be in the right power band.
If you really want to get max power out of your rig, you can go 5.13 gears, which will be definitely overgeared, but will get you more power to the wheels at any speed. The price will be that you will be around 2850RPM at 70MPH, which some would say that is too high.
 
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Stroker and regear are two completely different budget ranges. Just the labor bill from the machine shop on my stroker build would have paid for a regear.
 
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You're decision should be a simple one. Regardless of whether you go stroker, you need to regear. Skip the 4.88 and go straight to 5.13. Generally, people don't understand the .69 overdrive in the 42RLE and think 5.13 gears are to much, don't fall into that trap.

Also, add a transmission cooler and temperature gauge. That way there will be no more guess work, and you'll be all set for a stroker, when you're ready.

The numbers tell the story.....Your current RPMs, based on a 31.7" tire and 3.73 gearing, is to low and causing the transmission to work harder, generating more heat.
Gear
Road RPMs at given speed in miles per hour
1112339307860
262121724345
339513842767
42739551910
5---
6---
7---
8---
9---
10---
R87430586116

This, based on a 31.7" tire and 5.13 gearing, would put you where you need to be, plus give you that little extra, in case you ever go to a 33" tire.
Gear
Road RPMs at given speed in miles per hour
11544540510810
285429885976
354419033806
437513132626
5---
6---
7---
8---
9---
10---
R120242068412
 
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