more power
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Joined: Dec 2007
Posts: 7,987
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From: Boise, Idaho
The recommendation KemicalBurns was making was to change the gears that are in your axles, not your transmission.
If you put steeper gearing in your axles, it'll give you more oomph overall. If you have a 3.08, you can upgrade to a 3.55. If you have a 3.55, you can upgrade to a 4.10.
If you put steeper gearing in your axles, it'll give you more oomph overall. If you have a 3.08, you can upgrade to a 3.55. If you have a 3.55, you can upgrade to a 4.10.
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Junior User
Joined: Nov 2007
Posts: 84
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From: Helena, MT
What are the donor vehicles I can get them from and is it just the rear axels and if I change the rear axles can I change the leaf springs to give me more lift to hold heaver tow weight? also will I have to get a new drive line? and why not go strate to a 4:10?
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Joined: Dec 2007
Posts: 7,987
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From: Boise, Idaho
Any Bronco, F150, 250, 350, etc.
You'll have to change both the fronts and the rear since your Bronco is four wheel drive. The front and rear ratios have to match or you'll tear up your entire drive train the first time you use it.
The drivelines don't need to be changed.
The reason for not going straight to 4.10s is because, with smaller tires, it can limit your top speed.
With 4.10s and 235 75R15 tires, your RPMs will be at 2500 @ 65mph and 2900 @ 75. That's some pretty high RPMs for the 4.9. You'll enjoy the power around town, but you'll be whining out on the highway. It all depends on how you want to use the truck.
Granted, if you already have 3.55s, 4.10s are the next step anyway.
I don't know about the lift. Someone else may.
You'll have to change both the fronts and the rear since your Bronco is four wheel drive. The front and rear ratios have to match or you'll tear up your entire drive train the first time you use it.
The drivelines don't need to be changed.
The reason for not going straight to 4.10s is because, with smaller tires, it can limit your top speed.
With 4.10s and 235 75R15 tires, your RPMs will be at 2500 @ 65mph and 2900 @ 75. That's some pretty high RPMs for the 4.9. You'll enjoy the power around town, but you'll be whining out on the highway. It all depends on how you want to use the truck.
Granted, if you already have 3.55s, 4.10s are the next step anyway.
I don't know about the lift. Someone else may.
New User
Joined: Apr 2011
Posts: 19
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From: Milwaukie Oregon
I might also point out the second picture definitely shows a crack in that head, Owe, check your heads really well before having them sent to a machine shop so you don't get dinged for disassembly, Another way to boost compression is by putting a 240 head on the 300 carbed engine. Just make sure you do your homework and double check any modifications unfortunately with thye computer controlled EFI engines any mods could end up costing you during the emission testing if your county or state mandates it, it's against federal law to convert over to a dual exhaust if your truck came with a single exhaust system.
Lead Driver
Joined: May 2009
Posts: 6,815
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From: Tobyhanma, PA
Adding springs and/or a lift will NOT allow you to LEGALLY tow anymore. It doesnt raise the GVWR at all. That is based on a number of other items such as frame and wheelbase. Adding stiffer/taller springs may reduce the amount your truck sags when towing, that will help you handle a bit better but it is not advised to tow over the vehicles OEM tow rating.
Fleet Mechanic
Joined: Dec 2006
Posts: 1,925
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From: Phoenix, AZ
Now its against federal law to remove a fully functioning catalytic converter, so if you put on dual exhaust and don't put on two catalytic converters, (or 1 at the cross section), then that would be illegal. However dual exhaust on Broncos is a waste of money because the pipes have to maneuver around the T-case and it creates an unequal length of travel for the exhaust gas for each head etc. A single exhaust is the best, 3" for 302-351, for the 300 V6, maybe 2.5" or possibly still 3".
Moderator
Joined: Dec 2007
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From: Boise, Idaho
Yeah, I've never been one to recommend a dual exhaust. About all it does is look cool. Not only that, but it costs so much more for the same thing. Twice the pipe, double the mufflers, double the cats, plus the underside of the truck isn't designed for it.
For the I6, either a 2.25" or a 2.5" is sufficient. I have a 2.5" and love it. 3", from what I heard, starts to have negative effects on performance.
For the I6, either a 2.25" or a 2.5" is sufficient. I have a 2.5" and love it. 3", from what I heard, starts to have negative effects on performance.
New User
Joined: Apr 2011
Posts: 19
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From: Milwaukie Oregon
This is not true. If it is, I'd like to see the regulation.
Adding springs and/or a lift will NOT allow you to LEGALLY tow anymore. It doesnt raise the GVWR at all. That is based on a number of other items such as frame and wheelbase. Adding stiffer/taller springs may reduce the amount your truck sags when towing, that will help you handle a bit better but it is not advised to tow over the vehicles OEM tow rating.
Adding springs and/or a lift will NOT allow you to LEGALLY tow anymore. It doesnt raise the GVWR at all. That is based on a number of other items such as frame and wheelbase. Adding stiffer/taller springs may reduce the amount your truck sags when towing, that will help you handle a bit better but it is not advised to tow over the vehicles OEM tow rating.
The 1990 Federal Clean Air act states that if your truck is cat/controlled with a single exhaust system that you can't convert it to a dual exhaust system , Period! No muffler shop can install a two cat dual exhaust system on a single exhaust equipped truck. If the truck was converted prior to the 1990 revision and you have receipts to prove it then they can service the system but not convert it. It further states that it's a federal crime to do so. Any muffler shop can verify this. When youre in a state where there emission test/inspection stations this can be a serious problem if you show up with a shiny new dual exhaust system, It is in Oregon, Now if they persue it is another story, most of the time they just give you a fail slip, but it is the law!
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