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#4454354 - 07/09/17 03:00 PM Rear End Swap Ratios?
Delta Online   happy


Registered: 04/20/14
Posts: 1155
Loc: South Central PA
Looking to daily drive the S10 more to keep the miles off the GTI, but with the 3.42 gearset (confirmed with po) and locker it makes a terrible driver. Excellent fuel economy, but falls flat on itself up any hill or mountain. Heck even reverse is a chore up my incline driveway.

Build code on the truck says it originally came with 3.73's. I was wondering if a 4.10 out of an auto truck would be better suited for my location. Typical speed range here is 45-55mph. The NV1500 trans in it now's 5th gear ratio is .83. Swapping the rear isn't the hard part, it's my math that fail me. What do you guys suggest?
_________________________
'17 VW GTI 2.0T - 6MT - 7K
'15 Camry SE - 2.5 - 19K
'99 S10 - 2.2 5MT - 153K

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#4454362 - 07/09/17 03:07 PM Re: Rear End Swap Ratios? [Re: Delta]
DuckRyder Offline


Registered: 10/20/05
Posts: 4216
Loc: Atlanta
What size are the tires?
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  • 2007 Toyota Prius Touring
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#4454367 - 07/09/17 03:09 PM Re: Rear End Swap Ratios? [Re: DuckRyder]
Delta Online   happy


Registered: 04/20/14
Posts: 1155
Loc: South Central PA
215/75/15 tires.
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'17 VW GTI 2.0T - 6MT - 7K
'15 Camry SE - 2.5 - 19K
'99 S10 - 2.2 5MT - 153K

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#4454368 - 07/09/17 03:12 PM Re: Rear End Swap Ratios? [Re: Delta]
xxch4osxx Offline


Registered: 03/11/09
Posts: 2605
Loc: Cedarbrae, Ontario
I'd go for a 3.90, but thats just me.
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#4454371 - 07/09/17 03:18 PM Re: Rear End Swap Ratios? [Re: Delta]
DuckRyder Offline


Registered: 10/20/05
Posts: 4216
Loc: Atlanta
So nominally 27.6-27.7” ...

Let me see if I can find a calculator to do the math for us... I don’t seem to have one that will solve for other than a 1:1 high.
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#4454372 - 07/09/17 03:19 PM Re: Rear End Swap Ratios? [Re: Delta]
A_Harman Offline


Registered: 10/01/10
Posts: 6921
Loc: Michigan
Downshift into 4th gear if you want to climb a hill. If you put the 4.10 in the rear end in place of the 3.42, it's numerically the same as downshifting into 4th.

In 4th gear with the 3.42 diff you have 3.42 x 1 = 3.42 overall gearing.
In 5th gear with the 4.10 diff you would have 4.10 x .83 = 3.403 overall gearing.
Basically the same.

Or do you just want an overall peppier feeling with the truck in any gear?
You know the tradeoff; performance for fuel economy.
Or split the difference, and put 3.73's in it.
Or put the 4.10's in it, and if you don't like the gearing, put 10% taller tires on it to emulate a 3.73.
Or put the 4.10 in it, and swap in a T56 double overdrive tranny.


Edited by A_Harman (07/09/17 03:22 PM)
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#4454377 - 07/09/17 03:26 PM Re: Rear End Swap Ratios? [Re: Delta]
DuckRyder Offline


Registered: 10/20/05
Posts: 4216
Loc: Atlanta
You can play with https://www.ringpinion.com/calculators/Calc_RPM.aspx

That will give you an RPM in a .80 high gear.

Looks like a 4.11:1 is going to put you in the 2150-2200 RPM range at 55.
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  • 2007 Toyota Prius Touring
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#4454378 - 07/09/17 03:27 PM Re: Rear End Swap Ratios? [Re: Delta]
Linctex Offline


Registered: 12/31/16
Posts: 6178
Loc: Waco, TX
I had 3.73's in a 2.3 4-cyl Ranger and always wished it had 4.10's

I had to shift out of 5th in a strong head wind or going up a hill with the A/C on.
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#4454381 - 07/09/17 03:27 PM Re: Rear End Swap Ratios? [Re: Delta]
Delta Online   happy


Registered: 04/20/14
Posts: 1155
Loc: South Central PA
Overall I'd like the truck to be more peppier. I know that's asking alot out of the 120hp 4 banger, but the previous owner drove all highway and when the original rear end locked up he changed ratios. Around here I do have to go in 4th for a hill, but the mountains are a chore. 3rd gear is the only option and the engine is screaming for mercy to even do 40mph...

Edit. Thanks Duck, looks like what I might go with.


Edited by Delta (07/09/17 03:28 PM)
_________________________
'17 VW GTI 2.0T - 6MT - 7K
'15 Camry SE - 2.5 - 19K
'99 S10 - 2.2 5MT - 153K

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#4454386 - 07/09/17 03:30 PM Re: Rear End Swap Ratios? [Re: Delta]
DuckRyder Offline


Registered: 10/20/05
Posts: 4216
Loc: Atlanta
If you know the transmission ratios you can use:

http://www.tremec.com/calculadora.php

To get speeds in gears.
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Robert
  • 2007 Toyota Prius Touring
  • 2005 Honda Civic Sedan
  • 1972 Ford F100

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#4454405 - 07/09/17 03:46 PM Re: Rear End Swap Ratios? [Re: Delta]
BrocLuno Offline


Registered: 09/06/15
Posts: 5528
Loc: Kalifornia Kollective
I'd be looking at 3.90 also. A few RPM less in 5th on the highway vs 4.10's, but still more gear than you have now. Happy compromise smile
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#4454440 - 07/09/17 04:24 PM Re: Rear End Swap Ratios? [Re: Delta]
DuckRyder Offline


Registered: 10/20/05
Posts: 4216
Loc: Atlanta
It doesn’t look like anyone makes a 3.90:1 for it (it is a 7.5” 10 bolt right?).

2.73, 3.08, 3.23, 3.42, 3.73, 4.11, 4.30, 4.56.
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  • 2007 Toyota Prius Touring
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#4454448 - 07/09/17 04:31 PM Re: Rear End Swap Ratios? [Re: Delta]
Delta Online   happy


Registered: 04/20/14
Posts: 1155
Loc: South Central PA
Correct, 7.5/7.625 10 bolt. If it was the 8.5 out of the V6 I'd have more options. Looking like the easiest and cheapest option is to keep the locker and replace the ring and pinion. I'm assuming all the bearings are in good shape.
_________________________
'17 VW GTI 2.0T - 6MT - 7K
'15 Camry SE - 2.5 - 19K
'99 S10 - 2.2 5MT - 153K

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#4454460 - 07/09/17 04:44 PM Re: Rear End Swap Ratios? [Re: Delta]
E150GT Offline


Registered: 03/11/12
Posts: 1110
Loc: San Antonio, TX
3.42's aren't enough? My truck has 150 hp and 2.73's. I ask because I want to make my swap someday and I was thinking 3.55's. Generally for around town its not a problem with the 2.73 rear end but when I go down to the coast and fight the headwind I have to downshift on flat road into 4th to keep pace. She aint quick by any means. My old 1990 ford econoline with the 4.9 and C6 3 speed and 3.08's felt much quicker and probably was.
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#4454467 - 07/09/17 05:01 PM Re: Rear End Swap Ratios? [Re: E150GT]
Delta Online   happy


Registered: 04/20/14
Posts: 1155
Loc: South Central PA
Originally Posted By: E150GT
3.42's aren't enough? My truck has 150 hp and 2.73's. I ask because I want to make my swap someday and I was thinking 3.55's. Generally for around town its not a problem with the 2.73 rear end but when I go down to the coast and fight the headwind I have to downshift on flat road into 4th to keep pace. She aint quick by any means. My old 1990 ford econoline with the 4.9 and C6 3 speed and 3.08's felt much quicker and probably was.


Hah, your inline 6 has torque. My old 2.2 4 banger, not so much. Sideling Hill and Tuscarora Mountain are anywhere between 9% to 12% grade for about 3 miles either way. I typically run 3rd gear around 45mph, but like I've said the engine is begging for mercy. I've done faster, but it will start to get hot. You can run it to about 52, shift into 4th but it won't hold speed in that gear. Not looking for a speed demon, but anything to help it along.
_________________________
'17 VW GTI 2.0T - 6MT - 7K
'15 Camry SE - 2.5 - 19K
'99 S10 - 2.2 5MT - 153K

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