Gears for ZF5 and 35s 4.88 or 5.13

[RPM289]

Very interesting thread! I know RPM scares alot of folks but I had a 302 in my mustang that cruised at 70@ 3000 sweet spot of combo. Now I am rebuilding it and running a nasty 302 with 5 speed went with 4:11 and 235/60/15 to run at 3100 @ 75 in 5th, now if i want to pass 4th is a jump but right where I am making power. I have turned this 302 to 7500 with no issues and side stepping it with 5:13 gear in my drag car. 9in no issue with 5:13 gear! Anything in 3000 to 3500 is ok to me for street cruising.

I'm thinking about 4:88 in my bronco has 38 now will likely drop back to 35 or 36 at some point either going ZF or M50D so I am following this as I have to decide which gear to run have 4:11 now.

 

[kens bronco]

I have a mild built 302 with a zf and 4:56 gears. I'm very happy with the way it drives. I had 35's now running 37's. It wheels great, we're always on the interstate with it.
Kenny

 

[RPM289]

I have a mild built 302 with a zf and 4:56 gears. I'm very happy with the way it drives. I had 35's now running 37's. It wheels great, we're always on the interstate with it.
Kenny

Sounds like what I want can you give details? Speed / RPM etc

 

[75Bronc]

Kenny, would you prefer lower gears or do you think 4.56 gears are perfect? Did you feel a lack of gearing going to 37's?

What type of wheeling do you do? Do you think 4.88's and 35's is overkill?

Also, do you like the gap in the gears? Do you feel like it's too wide ratio?
Thanks!

 

[75Bronc]

Just wanted to update this thread. Been running 4.88's with 35's behind the ZF5 for several months now. Been on the interstate a bit more than expected and in the rocks quite a bit. So far I have been extremely happy with the gearing. I would recommend 4.88's for anyone running 35's and a ZF. I wouldn't mind a little lower transfer case gearing, but that's a whole other topic.

 

[Boss Hugg]

I wouldn't mind a little lower transfer case gearing, but that's a whole other topic.

So what RPM are you running at 70mph? I'm in 5.13s and about 2600 at 70.

 

[Hozr]

I was pretty happy with my ZF on 35's with 4:10/4:11 gears. Still runnung it with the 4BT in fact. RPM are a bit different but it puts me at 70mp in 5th at 1750 rpm. 65 is at 1600 which is the 4BT mileage sweet spot.

 

[75Bronc]

I'm actually right at 2600 while doing 70 Boss. Are your numbers actuals or based off a calculator? My 35's measure about 33.5" tall bringing me in at 2600 at 70.

Are you happy with the 5.13's? I almost went that route, I think I would have been happy with them. I don't go much over 70, I wouldn't mind a little more Highway RPM to get a little lower crawl.

 

[Boss Hugg]

I'm actually right at 2600 while doing 70 Boss. Are your numbers actuals or based off a calculator? My 35's measure about 33.5" tall bringing me in at 2600 at 70.

Are you happy with the 5.13's? I almost went that route, I think I would have been happy with them. I don't go much over 70, I wouldn't mind a little more Highway RPM to get a little lower crawl.

I'm happy with it. I'm going off my tach and gps speedometer. I think my 35s are around 34, 34.5. Maybe that's the difference. But I prefer to have the RPM to move the air. I don't think the MPGs are really bad if I keep it below 65, but anything above that, and it drops off significantly.

I do intend to install a doubler (cold duck) just because I want that option when crawling. Heck even in the yard sometimes it's nice to move slow. If I had a manual transmission, I probably would've stayed 4.88 or maybe even 4.56, but the torque converter is SUPPOSED to absorb the torque so I'm not too afraid I'll break gears. I won't be bouncing on the throttle in low-low for sure!

 

[NYLES]

5.13 gears are considerably smaller in size than 4.88 gears. I have heard the ring and pinion set is weaker than a 4.88 set.

I'm leaning toward 4.88

Keep the input coming!

I hAVENT BROKE ONE YET AND IF YOU INTEND ON USING 5TH YOU BETTER AT LEAST DO 5.13 AND IF YOU EVER THINKING OF 37S BETTER GO 5.38.

4.88 ITLL BE A MUTT ON THE HWY

 

[PaveBronco]

I was pretty happy with my ZF on 35's with 4:10/4:11 gears. Still runnung it with the 4BT in fact. RPM are a bit different but it puts me at 70mp in 5th at 1750 rpm. 65 is at 1600 which is the 4BT mileage sweet spot.

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