4.10 to 3.55 swap for $85 -- worth it? (Rear only)

[Golden Helmet]

With all this discussion (and some on another forum where this was mentioned) apparently you cant get 4.10 gears in liberalfornia.... (maybe just after a certain year of production, they consider it no different than tampering with exhaust/emissions equipment)
Don't believe it, do a search. Lol I was about to call a guy out, but wanted to have all the facts first. Glad I researched it.

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Do you have a source for that? I did a quick Google search and all I found was one thread on a Mustang forum, and all the replies were people telling the OP (and the dealership that told him it was illegal) he was wrong.

 

[79jasper]

Do you have a source for that? I did a quick Google search and all I found was one thread on a Mustang forum, and all the replies were people telling the OP (and the dealership that told him it was illegal) he was wrong.

Nope, Same. Just forums. Lol
Still cant say I believe it, but wouldn't surprise me.

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[DrCharles]

"Don't believe everything you read on the Internet." - Abraham Lincoln, 1860

 

[Randy Bush]

Have you checked on what the ratio is in your transmission. Should be a tag on the side of it. If it is not a wide ratio, .77 in 5th, might consider that route too.

 

[nj_m715]

[QUOTE="The_Josh_Bear, post:
$80 to set up gears is amazing. I would be all over that, it's like a 6 hour process if you don't do it often. I want a TruTrack something fierce in my Sterling 10.25 so I'll still have to figure that out some day.[/QUOTE]

80$ was for setting up the gears, not tearing down and rebuilding the rear

I put a detroit in my truck. it wasn't bad, just had to adjust the shims, didn't touch the pinion gear
it made a huge difference on steep dirt roads

 

[264WSM]

You will be happy. In my 89 IDI turbo 5 spd - I went from 16.5 mpg to 20.5 mpg unladen. Towing small stuff was not an issue - watch your EGTs and downshift over 1000* (if your gauge is after the turbo, 1250* if before the turbo), keep your boost off of the max. When I hooked on to my gooseneck and back-hoe I was grossing 26K. If I had to start on an incline, I would start in the Low Range of the transfer case. Go thru all 5, put the trans and transfer case in N, put the transfer case in High, then the transmission in 2nd and go thru them again. Eventually the transmission got tired and I had it rebuilt with gasoline gears. This gave me a lower first and second and I don't need to use the Low range anymore.
I have an independent front axle with 3.54s in it. $100 come and get it. I am about 600 miles from Spokane

 

[gfemling]

“If I had to start on an incline, I would start in the Low Range of the transfer case. Go thru all 5, put the trans and transfer case in N, put the transfer casein High, then the transmission in2nd and go thru them again.”

Okay interested in this technique’s pro/cons. Had my T19’s 1st gear go out on trip towing 6k RV trailer (3.55 gears, Hypermax turbo, 265-16 tires);successfully nursed it home 1k miles by mainly timing stop lights and running stop signs (on secondary roads ;-)). Did try using low range to get going and shift on-the-fly out of low range into high with some success but always a bit of gear clash. One problem was doing gear change sequence quickly enough to keep enough forward motion going. Any suggestions would be appreciated. Really appealing to have this as an option if can better perfect and be sure not doing damage to transfer vase& trans gears. Others experiences & thoughts?

 

[Isaac Ristow]

“If I had to start on an incline, I would start in the Low Range of the transfer case. Go thru all 5, put the trans and transfer case in N, put the transfer casein High, then the transmission in2nd and go thru them again.”

Okay interested in this technique’s pro/cons. Had my T19’s 1st gear go out on trip towing 6k RV trailer (3.55 gears, Hypermax turbo, 265-16 tires);successfully nursed it home 1k miles by mainly timing stop lights and running stop signs (on secondary roads ;-)). Did try using low range to get going and shift on-the-fly out of low range into high with some success but always a bit of gear clash. One problem was doing gear change sequence quickly enough to keep enough forward motion going. Any suggestions would be appreciated. Really appealing to have this as an option if can better perfect and be sure not doing damage to transfer vase& trans gears. Others experiences & thoughts?

not a good idea, won't take much to wipe out a tcase doing that. i used to do it in my willys jeep but i would put the tcase in natural from low then put the trans in first and revmatch the tcase into high range but this was a twin stick tcase on a 47 willys. tried it once on my ranger said never again. i could do it in the willys without any grinding

 

[JDierk]

Too bad you ain’t closer, I’d swap you front and rears free. I want 4.10 and have 3.55.


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I am in NW Ohio. I have a set of 4.10 front and rear that I pulled out and put in 3.55. If they will work can try to work something out for you to get them.

 

[Hybrid]

Hi guys, very interesting reading and lot,s of knowledge here. I got 1992 E 350 dually with non turbo 7.3 and E4OD trany (former ambulance, rear wheel drive). I am converting this vehicle to RV. Got trany rebuild, new tires (the same size as the original 6 - Thunderer Commercial CLT LT225/75R16 E/10PR BSW ) Just started driving the vehicle around and yes I can get most 9.8 mile per gallon. Very poor mileage. I did look at rear differential, no marking any type or tag with info. So after lot's of reading I'd like change gears in differential to get better mileage. I am down south Florida in Naples and my trips will be mostly to Florida Keys with small boat towing behind on flat as Florida is. Any suggestions before I take the differential apart? Is there cross reference by VIN number to get info for gears? I am attaching sticker from the door if that will be helpful. Appreciate any input.
Denny.

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[renjaminfrankln]

Yeah I know I've been looking around at it... ive heard 305/75R-16 fits stock without rubbing just a little bumper adjustment but hard size to find. 315/75 is easier to find but I dont want to deal with rubbing. So I'd have to run 285/75-16 which is only about 5% bigger. I may run them anyway, ha!

Bigger tires do look way better on these rigs, I'll never dispute that!

I need tires anyway, and thought pretty hard about getting taller tires. But even with 315/75's it's a 9% increase according to a tire calculator online, 3.55's are a 13.4% increase in speed at the same RPM.
Bigger tires also make more rotational inertia to get going, but changing gears doesn't change that variable.

But all that said it's a simple way to lower revolutions per mile for sure.

Yep I’ve done the math as well. Only solution is to drop to 3.55.

 

[snicklas]

Looking at you tag, the axle code of F2 is limited slip 4.10. So you could step up to a 3.55, or go with a auxiliary overdrive unit, like a gear vendor....

 

[79jasper]

For that moving ******* box, plus planning to tow, a O/D unit would be a much better option.

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[raydav]

3.55 gears

What is your trans? Will 3.55 be the final ratio?

My van is 9K#. I get about 5# of boost under rather heavy power.

I have 3.55 with a 0.7 OD which gives a final of about 2.5. It works fine over the road.

On hills and/or with a trailer I gear down. Cross country with no trailer it gets about 15 MPG.

 

[The_Josh_Bear]

ZF5