differential ratio swap wagon H190

[Stupid_fast]

Hello all, I've been doing some reading and have not found my answer.

 

I have 510 wagon with stock H190 , 3.889 gearing, 195-55-15(22.5") and a early WR ZX gearbox (3.32, 2.077, 1.308, 1.0, 0.864) and going to be dropping in a late CR/tall OD ZX gearbox(3.062, 1.858, 1.308, 1.0, 0.745)

Currenly with 3.889/0.864 5th its 72.7mph @ 3500rpm which is acceptable economy and keeping the motor in a comfortable rev range( at the bottom of the power band) With the new gearbox 3.889/0.745 5th it will be 72.2mph @ 3000rpm which will put it at what feels like the bottom of the torque band. This is good for cruising and economy, but acceleration and top speed will hurt for track and performance use.

 

All though I love to cruise at 80mph, this is not a DD and the shorter gearing will be more to my liking.

 

So I want to swap in a 4.375 ratio from a truck H190.

This will make 1-2-3-4 super close ratio for acceleration, and put the tall 0.745 5th gear for 75mph at 3500rpm and 128mph top end at 6000rpm. Seems a good sacrifice between street usability and rally style gearing to wake up the low power motor.

Even a 4.6 ratio would be nice being 71.4mph at 3500rpm !! Still streetable ... Shift points aren't even much different.

 

 

My question is are the pinion/ring gear bolt on from the later 73-80 trucks with h190's ?? Where else can I source a 4.375 ?? Even a 4.11 would be okay if it was all I could swap.

Really want to do this soon.

 

I know there are different carriers, but I have not seen any info on gear interchangeability.

 

I can get a speedo gear from nissan for the short gearing.

 

Thanks.

[datzenmike]

Fifth is not an acceleration gear, like for passing, and fourth should always be used for this at any speed. Acceleration for passing will thus be unchanged using either transmission.

 

I hear ya on the 4.375 and the first 4 gears. That will really wake them up.

 

Instead of swapping gears just swap your wagon spline side gears into a truck diff and swap it in.

 

http://community.ratsun.net/topic/10748-h190-spider-gear-swap/

[Stupid_fast]

I say acceleration in 5th for whenever I get my car prepped and safe enough for track use. I'll probably exceed 95mph that 4th gear will top out, in this case 5th will be nice to get 110-120mph with 4.375's.

The 5th gear will still be more tall than what I have now, being 3mph faster at the same revvs.

Also my motor does not make much power below 3000rpm, its only where it starts to wake up and it has a nice power balance at 3500rpm on the freeway right now, IMO its about the right speed for its current tune.

 

There will be no issue of different driveshaft bolt pattern, ect? Okay, thank you. I will go try to find a diff from the junkyard. Will the later H190 D21 diff drop in the same? Or only the 521 and 620's ?

 

edit, nevermind I see how it goes in now. Thanks for the help, datzenmike ! I needed a bit of a jolt to picture how it worked.

 

I am only confuse about one thing, there are different size front case things that hold the pinion, is there any difference in pinion gear length ? does it not need to come over with the ring gear?

[josh817]

If our 3rd members can swap (bolt right in) I will gladly trade you my stock 521 3rd member for your 3.89 member. I want a good highway cruise.

[ggzilla]

120 mph in a 510 wagon? That's stupid fast.

[datzenmike]

....

I am only confuse about one thing, there are different size front case things that hold the pinion, is there any difference in pinion gear length ? does it not need to come over with the ring gear?

 

Not sure what you are asking. The diffs are basically the same, later ones use a stronger metal. The big difference is the small side gears. The axles slide into them on splines. The truck has 29 spline and your goon has 23?.... all you are doing is putting the goon side gears in the truck diff so your 23 spline axles will fit it.

[ggzilla]

All 521 used 4.375

Most 620

Some 720

No hardbodies IIRC

 

He's asking if all H190 pumpkins are the same length (snout + flange length) -- will stock driveshaft fit *any* H190 pumpkin?

[Stupid_fast]

If our 3rd members can swap (bolt right in) I will gladly trade you my stock 521 3rd member for your 3.89 member. I want a good highway cruise.

I replied to your PM.

 

120 mph in a 510 wagon? That's stupid fast.

With suspension tuning, better brakes, and more power I'm confident it will pull to 5th on a road course.

 

Not sure what you are asking. The diffs are basically the same, later ones use a stronger metal. The big difference is the small side gears. The axles slide into them on splines. The truck has 29 spline and your goon has 23?.... all you are doing is putting the goon side gears in the truck diff so your 23 spline axles will fit it.

Okay, I figured it out thank you.

 

He's asking if all H190 pumpkins are the same length (snout + flange length) -- will stock driveshaft fit *any* H190 pumpkin?

^^ I wanted to make sure there was no difference in the pumkin type .. I don't like running into surprises after I've acquired the parts.

 

Some sources indicate the hardbodied D21 did in fact come with a 4.375:1 H190a in some configurations... I have not verified this.

 

I pulled a 4.375:1 h190 rear end from a 74 620 in the yards, I will be dropping it in at the same time as the new ZX gearbox. With my cam and shorter powerband this should give me the gearing for best road and track performance and drivability.

 

Thanks for the replies.

[datzenmike]

Yes here are some with differet flanges for the drivshaft. Somewhen around '82-'83 the H-190 in the 720 4x4 changed to a larger yoke. The smaller old style yoke will not swap onto it. (different spline) After '83 the 4x4 started using a C200 diff but there are still some of these around. If getting one from a 720 4x4 do check the fit. 2wd are ok.