35” tires with 3.73 gears?

[BlueBronco]

I think people missed that OP is a dealer and this will be their 2nd demo/mannequin/FCTP Bronco that will be, most likely, test driven by customers.

If this is indeed the case, I would only put on 35's with the proper re-gear. Otherwise, potential customers will be getting a less than ideal impression of the Bronco their first time out.

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[vrtical]

if its the A10, its a whole new ball game and you have to do some math if you wan to try to compare it to the old dumpster truck transmissions. The A10 has 3 OD gears to start and a spread of 7 other closer ratios. IMO this combo wont be an issue given the use case.

 

[okbob]

if its the A10, its a whole new ball game and you have to do some math if you wan to try to compare it to the old dumpster truck transmissions. The A10 has 3 OD gears to start and a spread of 7 other closer ratios. IMO this combo wont be an issue given the use case.

Final OD gear is the final OD gear, no matter how old or new the transmission is. The transmission cooling system is for sure better, but gear ratio itself is just that.

 

[mpeugeot]

We have 35s on our OBX with 3.73s. it honestly drives like it did from the factory. The transmission is not hunting for gears and it doesn't lag at all.

I see zero side effects from our experience.

Exactly, I see a lot of people making these doom and gloom predictions with a 3.73, with a 10 speed (or 8 speed transmission this isn't an issue). So looking at the infamous jeep chart, they suggest that 4.56-4.88 gears are the sweet spot for 35" tires with a target RPM of around 3,000.

Well the Ecoboost motors outperform the Jeep 2.0T and 3.6 motors at 3000 RPM by a noticeable margin, and the 2.7 EB makes close to the jeep numbers at nearly 500 RPM less. At 3000 RPM the 2.7 EB is approaching 350 ft/lbs of torque and the 2.3 EB is approaching 275 ft/lbs. The Jeep 2.0 is just cracking 250 ft/lbs at 3000 RPM, and the Jeep 3.6 is stuck at 225 ft/lbs at 3000 RPM.

Gearing in the automatic transmissions is a wash between the two (the Rubicon is a different case) assuming the modern 8HP50. I am assuming the standard transfer cases on both (2.72:1). If you are crawling the 2.3 and the 2.7 are going to be using the torque converter below 1500 RPM (3 MPH), at 6 MPH you are already near 3000 RPM in first gear. Also highway cruise at 65-85 MPH will be 1500-2000 RPM in 10th gear, which you can always just lock out the upper gears as needed. 8th is 65-80 MPH is 2000-2500 RPM, which will easily push the Bronco along, even with a 3500# trailer in tow.

35" tires, while not optimal with the 3.73 are certainly going to be just fine for everyday driving and aren't going to blow anything up. They will be fine even off-road, but I wouldn't recommend that someone who is planning on extreme rock crawling build a non-locker, non-SBD, Bronco as a rock crawler (and I don't think anyone is suggesting that this will be used for that).

 

[Beachin 74]

I bet the trans is running hotter though.

And automatic transmissions don't like heat.

 

[mpeugeot]

And automatic transmissions don't like heat.

I will say that one disappointment I have with the Bronco is the lack of a big standalone transmission cooler. That would have been a big improvement regardless.

 

[vrtical]

I will say that one disappointment I have with the Bronco is the lack of a big standalone transmission cooler. That would have been a big improvement regardless.

Been an issue with Ford stuff forever, but at least for the most part there are always ways to upgrade and/or add fixes for those use cases outside norm. I use to do a lot of towing and have done upgrades in this area, doesn't take much to get the temps back down to reasonable levels. It would be nice if the factory did this, but then its always cost.

 

[IDyeti]

I will say that one disappointment I have with the Bronco is the lack of a big standalone transmission cooler. That would have been a big improvement regardless.

Thanks for that information, was debating about pulling my external cooler off my current rig, decision made.

 

[Silver-Bolt]

It will be a total dog.

 

[Paul Gagnon]

I bet the trans is running hotter though.

Especially if you are going to go off road.

 

[Tricky Dick]

I'd compromise with 33s. It'll still look great but retain most of the pep.

OTOH, I have a buddy that ran 33s with 3.55 gearing in his jeep for a long time. When he finally regeared to 4.56 he said it wasn't a big enough difference and he regretted spending the money.

 

[mpeugeot]

I'd compromise with 33s. It'll still look great but retain most of the pep.

OTOH, I have a buddy that ran 33s with 3.55 gearing in his jeep for a long time. When he finally regeared to 4.56 he said it wasn't a big enough difference and he regretted spending the money.

That's what I ended up with... 4.27's and 33's, it's going to be damn near perfect (although I would like to find a torsen for the front axle).

 

[edgeflyer]

Both transmissions in the Bronco have much lower gearing than an older transmission. This is why we can still run on the freeway with 4:7 gears. It is apples to oranges comparing the Bronco to a jeep in gearing selection. Also, Ford runs large transmission coolers on vehicles that need it unlike was previously mentioned. My FX4 has an awesome stand alone cooler.

 

[mpeugeot]

Both transmissions in the Bronco have much lower gearing than an older transmission. This is why we can still run on the freeway with 4:7 gears. It is apples to oranges comparing the Bronco to a jeep in gearing selection. Also, Ford runs large transmission coolers on vehicles that need it unlike was previously mentioned. My FX4 has an awesome stand alone cooler.

Actually, the new jeep 8 speed compares pretty favorably with the 10 speed, although the 10 speed has finer granularity the Jeep essentially starts and ends in the same bottom and top ratios as the Bronco 10 speed, which surprised me.

Gear	Jeep	Bronco
1	4.71	4.714
2	3.13	2.997
3	2.10	2.149
4	1.67	1.769
5	1.28	1.521
6	1.00	1.275
7	0.84	1.00
8	0.67	0.853
9		0.689
10		0.636

 

[edgeflyer]

Actually, the new jeep 8 speed compares pretty favorably with the 10 speed, although the 10 speed has finer granularity the Jeep essentially starts and ends in the same bottom and top ratios as the Bronco 10 speed, which surprised me.

Gear	Jeep	Bronco
1	4.71	4.714
2	3.13	2.997
3	2.10	2.149
4	1.67	1.769
5	1.28	1.521
6	1.00	1.275
7	0.84	1.00
8	0.67	0.853
9		0.689
10		0.636

Yeah, I forgot they did an 8 speed. I was more referring to the 4 speeds.

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