24 bolt wheels with BFG Bajas - Runflat or No Runflat

[T9000]

meant to reply on next post

 

[T9000]

Yes, putting a turbo 6.5 with 4speed in a A0-A1 truck would have the highest top speed.
Or just swapping the A0-A1 diffs into a turbo truck, same difference, gearing wise.

Please disregard my ignorance as I am not mechanically familiar with the truck, would something like this 2.56 ring & pinion gear set do it or there is more to it?

M998 HMMWV 2.56 5579501 DIFFERENTIAL RING & PINION GEAR SET 3020-01-191-8784 H1 | eBay

PINION: 16 TEETH. NOS Diff ring and pinion set.

www.ebay.com

 

[T9000]

_

 

[Elijah95]

Aha! So you engaged the Gravity Boosters aka downhill...I have the same transmission with 6.5L TD and maxed out at the 80mph on the speedometer, but didn't check with the GPS.
The transmission shifts smoothly and after it goes into overdrive, it's all high RPMs from there.
I will do another test using the GPS too after I finish all the engine fixes and report back.

I saw a chip and ECU mod by Heath Diesel, has anyone tried it?

1996-2000 Max E Tork Programming

You'll find brand name diesel performance parts at Dieselsite. Get advice for your truck from the owners who are also certified AMSOIL distributors.

www.dieselsite.com

Most turbo trucks have a different gear ratio to accommodate armored acceleration, that’s by in part why the 1123 6.5 NA 4 speed trucks are very fast on top end. I had mine up to 90 as well doing some wide open testing last winter and decided it felt like i was coming back into the atmosphere and backed way off


Sent from my iPhone using Tapatalk

 

[T9000]

Most turbo trucks have a different gear ratio to accommodate armored acceleration, that’s by in part why the 1123 6.5 NA 4 speed trucks are very fast on top end. I had mine up to 90 as well doing some wide open testing last winter and decided it felt like i was coming back into the atmosphere and backed way off


Sent from my iPhone using Tapatalk

Got it! Yes, Hammer laid out the ratios clearly. Are these differentials like in civilian trucks where it can be configured with different ratios by just changing a few parts like the pinion & ring and keep everything else the same?

 

[Maxjeep1]

Got it! Yes, Hammer laid out the ratios clearly. Are these differentials like in civilian trucks where it can be configured with different ratios by just changing a few parts like the pinion & ring and keep everything else the same?

I always Thought it was just an AMC model 20 diff. I’m sure someone here can confirm that. I was looking at Detroit lockers and I think it was the same

 

[T9000]

I always Thought it was just an AMC model 20 diff. I’m sure someone here can confirm that. I was looking at Detroit lockers and I think it was the same

Here it is and if that's the case, can we just pop in/ swap the two gear parts and keep the same bearings and all other parts the same?
Between front and back would be $600 + time, a great upgrade IMO?

 

[Action]

He could have, but I doubt it.

And to put all the numbers for gearing.

For the differentials themselves.
A0-A1 have 2:56
A2’s have 2:73 (4 spd, 65. NA)
ECV on up, 3:08 (4 spd, 65. Turbo)

Geared Portal hubs are 1.92:1

Transmissions
3rd gear is 1:1,
4th gear is .75:1

Final drive "axle" ratios
A0-A1 = 4.92
A2 = 5.24
ECV + = 5.91

Final driver in TOP gear
A0-A1 = 4.92 3rd gear
A2 = 3.93
ECV + = 4.44

Easy to see the A2 has the best gearing for top speed

What about a ratio for overdrive? I feel 4 shifts, so 1, 2, 3, 4, od.

 

[Hammer]

What about a ratio for overdrive? I feel 4 shifts, so 1, 2, 3, 4, od.

They are only 4 speeds, you are feeling the torque converter locking up to make it feel like another gear.

Transmissions
3rd gear is 1:1,
4th gear is .75:1

So .75 to 1 is the overdrive gear in the 4 speed transmissions (4L80E) in the A2 and up trucks.

 

[Hammer]

Here it is and if that's the case, can we just pop in/ swap the two gear parts and keep the same bearings and all other parts the same?
Between front and back would be $600 + time, a great upgrade IMO?

Yes, Dana 20 differentials, just like in the Jeeps.
And yes, doing a ring and pinion swap, properly setup, is the way to change to a number of different gears.
Thing is, getting the low numeric gear ratios are not common. Most offerings are 3.54 or up.
Easiest answer is to swap the differential itself out. Cheaper as well.

 

[Maxjeep1]

Yes, Dana 20 differentials, just like in the Jeeps.
And yes, doing a ring and pinion swap, properly setup, is the way to change to a number of different gears.
Thing is, getting the low numeric gear ratios are not common. Most offerings are 3.54 or up.
Easiest answer is to swap the differential itself out. Cheaper as well.

Dana 20 and AMC 20 are not the same. I think the AMC model 20 has an 8 3/4” inch ring gear. Dana 20 is a transfer case. I know Dana 30 is a front diff but I don’t think I have heard of a 20

 

[Hammer]

Sorry, I have always used those interchangeably. Still not right though...

 

[T9000]

Yes, Dana 20 differentials, just like in the Jeeps.
And yes, doing a ring and pinion swap, properly setup, is the way to change to a number of different gears.
Thing is, getting the low numeric gear ratios are not common. Most offerings are 3.54 or up.
Easiest answer is to swap the differential itself out. Cheaper as well.

The diagram should be for an AMC20 (or I thought it was), which is used in the H1 they say.
A brand new one is listed for $4k vs. $1.5k -2k re-manufactured vs. <$300 for just the ring & pinion?
But you are saying going lower is not common practice?
Maybe because the thinking is that trading torque for rpms is not a good idea? (in electrical engineering it is trading Amps for Volts or vice-versa, where the power Watts stays the same). In my ECV A1 case, the 6.5TD already has more torque and I don't have any heavy armor, therefore I think it would be an OK trade that the engine can handle? What are the ratios in the H1s with the 6.5TD?

 

[Coug]

The diagram should be for an AMC20 (or I thought it was), which is used in the H1 they say.
A brand new one is listed for $4k vs. $1.5k -2k re-manufactured vs. <$300 for just the ring & pinion?
But you are saying going lower is not common practice?
Maybe because the thinking is that trading torque for hp is not a good idea? (in electrical engineering it is trading Amps for Volts or vice-versa, where the power Watts stays the same). In my ECV A1 case, the 6.5TD already has more torque and I don't have any heavy armor, therefore I think it would be an OK trade that the engine can handle? What are the ratios in the H1s with the 6.5TD?

It's hard to find any gearing higher than the 3.54 because of the portal hubs aren't very common. They almost double the gear ratio, so you have to start out a lot higher.
And as the HMMWV is a relatively uncommon application in the real world, there just isn't much out there.

Trading low end torque for top end speed is fine, but within reason. theoretical book top speed with the 2.53 gears would be around 86mph, which also happens to be the max speed rating for the military tires a lot of us run. If 95% of your driving is cruising the highway, then you should be fine.
On the other hand, if you like to off road a lot, then the lower end torque is a lot more useful than top end.

It all depends on what you want to do with it.

 

[T9000]

It's hard to find any gearing higher than the 3.54 because of the portal hubs aren't very common. They almost double the gear ratio, so you have to start out a lot higher.
And as the HMMWV is a relatively uncommon application in the real world, there just isn't much out there.

Trading low end torque for top end speed is fine, but within reason. theoretical book top speed with the 2.53 gears would be around 86mph, which also happens to be the max speed rating for the military tires a lot of us run. If 95% of your driving is cruising the highway, then you should be fine.
On the other hand, if you like to off road a lot, then the lower end torque is a lot more useful than top end.

It all depends on what you want to do with it.

The info we got is that the A0-A1 is the fastest and has a 2:56 ratio.
The ECV already has more torque, and we are not talking about some huge increase...going from 70mph to 86mph is about 20%, so definatelly it sounds like a resonable trade since the ECV A1 was meant to carry heavy armor + munitions, in fact the delta between the 7800LBS curb weight and rated 12,100 GVW is 55%...of course that's a lot about the chassis, but the engine was part of those calculations in order to handle the load, so a 20% trade seems reasonable and will still have enough torque for off-roading.
Where I live 80mph is the low end of normal speed, cops get triggered usually starting above 82+, anything below you get ran over lol

I will do an actual GPS speed test to see how high it goes, it may be fine the way it is.

 

[Maxjeep1]

I think that turbo truck with 42’s would be just fine

 

[T9000]

I think that turbo truck with 42’s would be just fine

Do you mean on 16.5s?
Or on 17s?
Which brings us back full circle to the thread topic lol.

 

[Maxjeep1]

Do you mean on 16.5s?
Or on 17s?
Which brings us back full circle to the thread topic lol.

16.5 24 bolt even spaced

 

[Hammer]

The info we got is that the A0-A1 is the fastest and has a 2:56 ratio.

Fastest for gear ratios, yes. But needs the overdrive transmission to take advantage of that gearing.
BTW, for cost, I meant to just get take out differentials, ie,. surplus.
But if you have an ECV up truck, then your diffs/brakes are better.
Finding 2.56 ring and pinion sets will not be easy.
And don't forget the brick wall affect of driving these at speeds over 60 mph. Increasing speed really increases the wind drag.
I know if I cruise at 80 mph, and a headwind comes up, it slows me slow down. Usually not under about 70 mph though.

MaxJeep1 statement is that getting taller tires has the same basic affect of changing your gear ratios for higher stop speed. Of course other things need to happen to fit tires of that size, but still easily doable.

 

[T9000]

Fastest for gear ratios, yes. But needs the overdrive transmission to take advantage of that gearing.
BTW, for cost, I meant to just get take out differentials, ie,. surplus.
But if you have an ECV up truck, then your diffs/brakes are better.
Finding 2.56 ring and pinion sets will not be easy.
And don't forget the brick wall affect of driving these at speeds over 60 mph. Increasing speed really increases the wind drag.
I know if I cruise at 80 mph, and a headwind comes up, it slows me slow down. Usually not under about 70 mph though.

MaxJeep1 statement is that getting taller tires has the same basic affect of changing your gear ratios for higher stop speed. Of course other things need to happen to fit tires of that size, but still easily doable.

Changing the tires from 37” to 42” would increase the speed from 70mph to about 79.5mph, or about 13%. Given the amount of lifting and modifications required to fit the larger tire, it represents a relatively marginal improvement.
We need more lol
BtW, almost every HMMWV parts site has the 2.56 ring & pinion for about $300, but no matter how we slice it, we are trading torque for rpms or vicersa, when what we need is more power…
I am not a mechanical engineer, but I think this engine can do more…if we increase the amount of air that gets pushed in, the fuel and the cooling of course to remove the heat, how much more can this engine handle without overstressing it?
What’s the design margin? 50%? Higher?
Does anyone know? Has anyone boosted it higher with safe results?