OK...so in another thread I talked about how I changed to bigger wheels/tires and now the gearing is off. Option of changing the gearing (front and rear) is pretty costly so now I'm looking at trying to bullet proof my stock 4R100 transmission.

I've briefly talked with John at Domestic Diesel in Chino, CA regarding this.

Can anyone give me some advice on some options for what should be done to the transmission to bullet proof it?

 

A few questions:

How many miles currently on the vehicle?

How many miles per year do you anticipate?

What do you tow? How much does it weigh? How often? Terrain?

 

Current mileage 140,000 miles

Miles per year 5000-6000 daily driven

Tow - Occasionally tow a single open car trailer probably about 5,000 lbs with car and trailer. Never go off road.

 

John Wood built transmission.

John Wood Automotive down in Holtville, CA.

Stewart

 

What is your current gearing and tire size? A transmission is going to cost you 4-6K. If you are staying stock, I think the re-gear is a better idea. Rebuilding our transmission is not going to change the strain on it. As mentioned John Wood is great. BTS, and Ford-HD are also ones to consider. Since you are in Cali...John Wood will be highly recommended, especially since its only 3 hours away..

 

I had stock 16" wheels with 31.5" tires now I have 20" wheels with 34.5" tires.
Current gearing is stock 3.73 I believe.

Looks like I need 4.11 gears to get me back to the stock-ish final ratio. The truck just seemed more responsive before changing wheels/tires and I'd like to go back to that.

Any ideas on what gear changes should cost per axle? Mine is a 4X4. The shop I took it to doesn't do the gear changes and he estimates about $1200 per axle (parts and labor).

I'm in SoCal so anyone with a recommendation for a shop to get an estimate on that would be great.

 

Nothing you can do to the transmission will help that at all. A $6000 transmission will feel exactly as responsive as the one you have now.

My recommendation to upgrade your trans to last with the new, larger tires is to replace the aux trans cooler with one from a 6.0L F-Series. The added load on the trans causes heat, and this cooler will get rid of that heat.

 

So it's sounding like the consensus is that trans should be much lower on my list of upgrades and I think I'm in agreement with that.

My initial thought was that because I've heard some concerns about the 4R100 trans and was looking to compensate my gearing issues with some tuning, then I would want to build the transmission a bit.

Considering I'm not really into tuning that much, is a stock well maintained 4R100 trans with 140K miles probably still in good shape for a while?

 

I'd run it until it broke or problems appeared, especially if its like you say. Why throw 4K away?

 

Do a little more research. If anything the 4R100 lasts longer than most. As others have said work on other things first. Keep a reserve set aside for when it does need to be rebuilt and when you do get the HD kit installed but I wouldn't just go out and spend the money if it is working fine now. Though I would go out and replace the fluid if you haven't yet done so.

 

I was quoted 1K for both axles....Just not on my need to do list right now.

 

OK...dropped the Ex off tonight at the shop to have the new springs and shocks mounted. Decided to go with the upgraded trans cooler for now. Thanks everyone for the advice.