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View Full Version : Re-gearing a 7.3L w/35" tires.



Loser1
02-15-2005, 04:42 PM
Hey there folks....

I just pulled my new 5er on a 400 mile trip (200 miles each way to Glamis). It seems like my transmission was working a bit harder than it should, I saw temps of 195*. I know that 195* isn't bad but I always found myself obsessed with the gauge.

Now I have 35" tires and the stock 3.73 gear. What are the suggestions? A set of 4.10s would put me right at stock but would going up to a 4.30 be too much?

Thanks for the help!

L1

Ps. What should I expect to pay for the swap?

Pss. CustomMotorsports, right off of the 91 FWY in Corona told me that that they do not regear Diesels do to a loss of performance after the gear swap. I know who wont be touching my truck http://www.socaps.comimages/graemlins/rofl.gif

wampaku
02-15-2005, 05:37 PM
i would say 4.10's for mileage an 4.30's for the extra torque and pull. rpm's may tack a little higher than normal(200-300 more) but 4.30's for that 5'er

james

Tom
02-15-2005, 06:21 PM
how heavy is the 5th wheel trailer?
-T

Loser1
02-15-2005, 06:58 PM
The 5er is a Weekend Warrior LE3505. I haven't weighed it yet but guesstimating it comming in close to 14K loaded and truck close to 8K loaded. I know that I'm a bit overloaded and I'm hoping gears will help move the load and be a bit easier on the trans. It seems that 4.10s will put me close to stock but I just wondering if I need the 4.30s for some extra nuts. The 4.30s with 35"s should feel like 4.10s on a stock tires.

What should I expect to pay for the swap?

Thanks,

L1

Tom
02-15-2005, 07:08 PM
4.56's are probably what you need. That's about 4.10's with stock tires (stock dually ratio).

4.30's would help a lot.

With that load, I wouldn't consider 4.10's.
-T

Loser1
02-15-2005, 07:29 PM
Tom,

Thanks for your help. I've been on 4lo.com looking at ratios. I'm leaning towards the 4.30s but now also considering the 4.56s. I just don't want to take my truck out of the sweet spot of the torque curve.

http://www.socaps.comimages/graemlins/confused.gifDecisions...decisions...it's only money....decisions...it's only money....what did I get myself into...sell the toys...decisions" http://www.socaps.comimages/graemlins/confused.gif

Sorry, just the voices in my head...

Tom
02-15-2005, 09:07 PM
I just don't want to take my truck out of the sweet spot of the torque curve.




That all depends on how fast you tow. 55 is a bit differnt than 65.

With your weight, I'd cap it at 60 and call it a day.

That's a big load for a SRW truck.
-T

bobsquatch
02-15-2005, 09:53 PM
Hey Loser, you are 4x2 correct? It is much cheaper to gear up one axel. I recommend the 4.56 ratio fur sure and if its a bit low you only have to live with it till you get your 37" tires http://www.socaps.comimages/graemlins/burnout.gif

Tom
02-15-2005, 11:35 PM
Hey Loser, ...



That sounds so....mean! LOL
-T

Loser1
02-16-2005, 06:52 AM
Sometimes I wish the truck was a 4X2 but other times I glad it's a 4X4 http://www.socaps.comimages/graemlins/smirk.gif

I'm really leaning towards the 4.30s. That would bring my effective gear ratio to a 3.88 which is just a bit shorter than the stock 3.73s. The trailer is heavy but I'm only just a bit over GCVWR (about 800lbs on the trailer and 400lbs on the truck).

I just don't want to redline on the FWY empty.

L1

Tom
02-16-2005, 09:43 AM
I just don't want to redline on the FWY empty.

L1



If you drive the truck a lot empty and don't drive in the hills all the time, that's a safe bet.

For hills and trailering heavy more than once a week...then I'd consider 4.56's. (or if you're going to 37" tires and retiring the truck to off road duty)
-T

bobsquatch
02-16-2005, 12:59 PM
Hey Loser, ...



That sounds so....mean! LOL
-T



That's funny, I was thinking just that when I wrote it http://www.socaps.comimages/graemlins/rofl.gif

Loser1
02-16-2005, 01:07 PM
Hey Loser, ...



That sounds so....mean! LOL
-T



That's funny, I was thinking just that when I wrote it http://www.socaps.comimages/graemlins/rofl.gif



My therapist tells me that acceptance is the first stage of recovery http://www.socaps.comimages/graemlins/ooo.gif

PITBULL62
02-16-2005, 03:22 PM
Loser, theres a good thread over on TDS.COM. Im running 38" tires w 4.56. I plan on lowering my truck and running 35's and plan to keep running the 4.56....My point is the 4.56 with 35" tires is supposed to be like stock tires w 4.10 gearing, much like the duallies run stock...whatever you do dont run 4.10 waste of money..IMO Wont notice any difference

Loser1
02-16-2005, 03:59 PM
What fourm is the thread about the 4.56s in? I've been looking/following for a couple of days now and haven't come across it and would like to review it.

My math.....34.8 (BFG 315/75/16)/ 31.6 (stock 265/75/16) * 3.73 = 4.10s to get back to stock.

So 4.30 would get me an effective ratio of about 3.90. whick is a bit shorter that stock.

If I go with a 4.56 my effective ratio would be about a 4.14. At 4.14 I'm guessing I'd tach about 2500rpms at 70 which would suck the fuel.

I think, but I could be wrong and usually I am, that the 4.30s would be a nice compromise.

PITBULL62
02-16-2005, 04:23 PM
I believe the 4.56 on 35's would give an rpm of 2250, dont quote me on that? anyways do a search on woodsracer or gordon24, I think he actualy did the 4.56 on 35's and gave his results on it, which convinced me to stay w the 4.56 w the 35's....4.30 is good to tho, in my case i dont want to spend AANOTHER 1300 dollars to go to 4.30, only reason im staying w 4.56. 2250 isnt that bad and will give me the extra oomph! like i said it was said it would be like stock tires on a dually w 4.10 from the factory, that is the statement that convinced me it would be ok....just my opinion

PITBULL62
02-16-2005, 04:24 PM
also type in "gears" along w those handles. If all else fails, PM smokeywren he'll have an answer for you

MSDSMAN
02-16-2005, 04:42 PM
I would go with the 4:30s I had the same problems so I had 4:10s installed, wish I went with the 4:30s.....
Diff Works in Riverside did mine for about $1650 http://www.socaps.comimages/graemlins/burnout.gif

Bullfrog
02-16-2005, 04:56 PM
Suck fuel is right! I Have an F-450 with a 4.88 and I tach about 2800rpms @ 70 mph. In turn I get about 9 MPG. If I were you I would go for the nice compromise (4.30 gear).

Loser1
02-16-2005, 05:17 PM
MSDSMAN,

JSC=Johnnys Speed and Chrome!!!!!!!! I had a 2 seater with a 2165 and dual 48s!!!!!!! I loved that car!!!!!!! http://www.socaps.comimages/graemlins/burnout.gif

Tom
02-16-2005, 05:26 PM
Suck fuel is right! I Have an F-450 with a 4.88 and I tach about 2800rpms @ 70 mph. In turn I get about 9 MPG. If I were you I would go for the nice compromise (4.30 gear).



4.88's with 225/70-19.5's...sure. That's a lot of gear for stock height tires!

Try 2225 RPMS at 70mph with 4.56's and a 34.8" tire.
Your trailer is pretty heavy. If it was my truck, I'd be putting 4.56's in it. 4.30's is a good compromise, if you don't tow a lot.
-T

bobsquatch
02-17-2005, 12:43 AM
Don't forget, to achieve any accuracy you need to get out the tape and measure your tires. Just because thay say 35" or 315/**/** doesn't mean squat. I have seen 2" discrepencies from claimed/actual circumference. http://www.socaps.comimages/graemlins/shocked.gif By the way loser, did you notice my Avitar??? http://www.socaps.comimages/graemlins/peace.gif

Tom
02-17-2005, 01:54 AM
Did you get all that info, Loser?

LOL

Loser1
02-17-2005, 07:37 AM
bobsquatch,

Avitar....You mean the 2 seat Highjumper catchin' air?!?!?! Aren't the dunes great? We are there last weekend and the Desert Verbina (purple flower) was in bloom in the North Dune Closure and down by the canal. Again great place but don't tell anyone about it!!!!! http://www.socaps.comimages/graemlins/laugh.gif

bobsquatch
02-17-2005, 09:53 AM
UUUHHH, what place http://www.socaps.comimages/graemlins/wink.gif I heard they closed the whole world east of the lagunas.

zurniega
02-20-2005, 08:07 PM
Well guys I was going to run a new thread but this one answered all my questions. I so happen to have the exact same dilema. 35" tires w/ 3.73 gears. I'm pretty sure 4.30's just in case i want larger tires http://www.socaps.comimages/graemlins/stirthepot.gif http://www.socaps.comimages/graemlins/stirthepot.gif http://www.socaps.comimages/graemlins/stirthepot.gif http://www.socaps.comimages/graemlins/stirthepot.gif http://www.socaps.comimages/graemlins/stirthepot.gif http://www.socaps.comimages/graemlins/burnout.gif http://www.socaps.comimages/graemlins/burnout.gif http://www.socaps.comimages/graemlins/burnout.gif http://www.socaps.comimages/graemlins/burnout.gif http://www.socaps.comimages/graemlins/burnout.gif http://www.socaps.comimages/graemlins/burnout.gif

Just one more question does anyone know what makes are the front and rear axles on a 03' f-250. for the life of me i cannot find it. http://www.socaps.comimages/graemlins/help.gif http://www.socaps.comimages/graemlins/help.gif http://www.socaps.comimages/graemlins/help.gif http://www.socaps.comimages/graemlins/help.gif http://www.socaps.comimages/graemlins/help.gif http://www.socaps.comimages/graemlins/help.gif http://www.socaps.comimages/graemlins/help.gif http://www.socaps.comimages/graemlins/help.gif

Tom
02-21-2005, 08:46 AM
Well guys I was going to run a new thread but this one answered all my questions. I so happen to have the exact same dilema. 35" tires w/ 3.73 gears. I'm pretty sure 4.30's just in case i want larger tires http://www.socaps.comimages/graemlins/stirthepot.gif http://www.socaps.comimages/graemlins/stirthepot.gif http://www.socaps.comimages/graemlins/stirthepot.gif http://www.socaps.comimages/graemlins/stirthepot.gif http://www.socaps.comimages/graemlins/stirthepot.gif http://www.socaps.comimages/graemlins/burnout.gif http://www.socaps.comimages/graemlins/burnout.gif http://www.socaps.comimages/graemlins/burnout.gif http://www.socaps.comimages/graemlins/burnout.gif http://www.socaps.comimages/graemlins/burnout.gif http://www.socaps.comimages/graemlins/burnout.gif

Just one more question does anyone know what makes are the front and rear axles on a 03' f-250. for the life of me i cannot find it. http://www.socaps.comimages/graemlins/help.gif http://www.socaps.comimages/graemlins/help.gif http://www.socaps.comimages/graemlins/help.gif http://www.socaps.comimages/graemlins/help.gif http://www.socaps.comimages/graemlins/help.gif http://www.socaps.comimages/graemlins/help.gif http://www.socaps.comimages/graemlins/help.gif http://www.socaps.comimages/graemlins/help.gif



The front is known as a Ford Dana 60. The rear is known as a Ford 10.5" by Visteon. Formerly owned by Ford and called Sterling 10.5". Just tell them you have a Ford Superduty and it has the Dana 60 straight front axle. If they're worth their weight in salt, they'll know.
-T

zurniega
02-21-2005, 11:14 AM
Thank YOU http://www.socaps.comimages/graemlins/computer.gif http://www.socaps.comimages/graemlins/computer.gif http://www.socaps.comimages/graemlins/computer.gif http://www.socaps.comimages/graemlins/computer.gif http://www.socaps.comimages/graemlins/computer.gif