Mack 5speed swap

[Kenny_dodge98]

Whats a better trans to swap in my 90 ch613 has a 300e6 and a 5speed i pull logs so im loaded above 80,000lb every load and having so few gears really kills the truck like it takes me miles to get up to speed. iv found a mack 9 speed from a r model  and a eaton fuller 9 speed from a newer ch that had a e7 motor which would you guys recommended and why and what all do i need for the swap other then trans a air supply for shifter and a drive shaft 

[Maxidyne]

Your truck was designed to haul at weights of 80k pounds or less on flat to rolling paved roads. Above 80k pounds you need more than 300 HP and you need a lower 1st gear to start even 80k loads on steep hills and off road. You could swap in a 350 or 400 with more gears, but it makes more sense just to swap trucks.

[Kenny_dodge98]

It takes off fine 1st through 4 its just that with the five speed i shift into 5th at 40 mph im not new to trucks or driving im just new to mack thats why i asked about the transmission i dont need your opinion on my truck i just need facts about what i asked for

[Maxidyne]

Sorry if I was a bit too direct and sounded harsh. The 300 Maxitorque with a 5 speed works fine doing what it was designed for, but if you need more power or deeper gear reduction you'll need to swap the engine and/or transmission. That can be done, but it's questionable if it's worth the time and cost on a 28 year old truck. That said, if you just need a deeper low gear, the 6 speed Mack transmission isn't that hard a swap and will solve that problem. You could swap in a 350 HP Mack engine, but it'll need a close ratio transmission to work. Swapping in a close ratio transmission with 9 or more speeds won't accomplish much, as the 300 HP Maxidyne produces over 90% of full power clear down to the RPM you downshift at.

[Kenny_dodge98]

The truck has 167,000 original miles on it it was owned by a farmer and only used 2 months a year so its worth the swap to me as far as cost im a very  competent mechanic and my little brother is a truck mechanic iv found both trans locally for less then 500 bucks ( helps to be a 3rd generation driver) im just looking for info on rather the mack 2090 is better or worse then the eaton fuller 9

[j hancock]

The T-2090 is a solid transmission and the swap will be easier staying within the Mack family.

[macks in nigeria]

36 minutes ago, Kenny_dodge98 said:

The truck has 167,000 original miles on it it was owned by a farmer and only used 2 months a year so its worth the swap to me as far as cost im a very  competent mechanic and my little brother is a truck mechanic iv found both trans locally for less then 500 bucks ( helps to be a 3rd generation driver) im just looking for info on rather the mack 2090 is better or worse then the eaton fuller 9

We are all here because of our love for mack trucks or the fact that we use them,you might not like every opinion you get but be rest assured it is given in good faith.Wish you luck with your swap.

[HeavyGunner]

You don’t “need” more than 300hp (though it would be nice) to pull the load you’re already proving that by doing it with a five speed. Why not get a 12, 13, 15 or 18 speed to put in it. With the closer ratio between gears you can keep your truck in the power band in every gear and not lug it to death trying to get up to speed. I pull an 11 axle A train with a 10 speed and I feel your pain. Even with 500 ponies it takes that Detroit miles to get up to speed in flattop rolling hills. Strong head wind or even worse strong cross wind forget about using 10th gear. 

Edited February 5, 2018 by HeavyGunner

[Lmackattack]

First off what rear end ratio do you have?  Mack made some of the slowest and fastest transmission and the rear end gearing was very different.

 

 

[Kenny_dodge98]

Dont know i believe 5.73 it tops out at 70 empty the truck is all original it'll pull a load 65 it just takes miles to get there 

[Lmackattack]

Ok that is why I was asking... with 5.73 rears you are kinda limited. That Mack 5 speed has a .60 overdrive in 5th gear and should put you at 74MPH at 2100RPM . If you can only do 65 I think you may have a low RPM pump setting  (1800RPM) you can turn that pump up to a normal 2100RPM pump and it will run alot better but it will drink some fuel.

 

 

for example here are the top speeds at 2100 rpm with 22.5 tires and 5.73 rears

 

Mack 5 or 6 speed direct with 22.5 tires and 1:1 trans 44MPH in top gear

T2090 Mack 9 speed  with 22.5 tires and .71 OD puts you at 62 MPH in 9th gear

12 speed mack with 22.5 tires and .78OD 57MPH in 12th gear

8LL with 22.5 tires and .60 OD puts you at 60 MPH in 8th gear

 

you can see from where the speeds fall between a direct trans or a .60 to .78 over drive

 

Trent

 

 

 

 

[880joe]

the Mack 9 speed would give you less of a gap between gears but you will lose top end speed as it is a .71 overdrive and the 5 speed you have is a .60 overdrive. A 2060,2070,or a 2080 would work in your truck but that will not help on the big gap between the top 2 gears as it is the same on all those transmission you only gain gears on the low side 

[Lmackattack]

I think his best bet for now is to turn the pump up to a 2100 maxidyne setting and see if he likes it better? it wont change the gap between 4th and 5th but it will have more balls pulling thru the gears. I pump re cal around here is about $150 if you pull and re install it yourself.

 

[Kenny_dodge98]

Truck has low pro 24.5  285-75-24.5 i believe i could stand to lose a little top speed as 95% of my driving is in 55 mph zones it just sucks to slow for a curve and then have to wait a mile or 2 to get back up to 55 sounds like the mack trans is a better swap then the fuller

[1965]

Everybody I’ve known that did this; the only thing they achieved (on the black top) was more gear shifting. Same speed at same spots. If you didn’t do something to the pump.

[Maxidyne]

With the wide ratios of the 5 speed you have 300 gross HP at peak power, around 1600 to 1800 RPM, dropping down to around 270 HP at the bottom and top of the engines operating range. With a 9 or 10 speed close ratio transmission you can stay closer to peak horsepower so you'll drop down to maybe 290 HP at the shift points, but on average you're gaining maybe 10 HP for a 3 percent increase. That increase is negated by the additional power interruptions of the extra gearshifts, so really nothing is gained in acceleration with more gears.

[terry]

if you are grossing over 80.000 lb's you need a bigger motor, a 300 is going to struggle to get to speed.    terry

[Lmackattack]

4 hours ago, Kenny_dodge98 said:

Truck has low pro 24.5  285-75-24.5 i believe i could stand to lose a little top speed as 95% of my driving is in 55 mph zones it just sucks to slow for a curve and then have to wait a mile or 2 to get back up to 55 sounds like the mack trans is a better swap then the fuller

low pro 24.5 is basically the same overall diameter as a 11R22.5. The rev per mile between the two tires is a difference of less than 1mph in top gear.

You are in a pinch here. You can turn the RPMs up to 2100 safely but it still does not change the fact of the huge overdrive that the little 300 still pulls in. I had a friend with a low RPM motor turned up to 2100 and it did great pulling 73,280 around with a 6 speed but it would drink the fuel. I ran out of fuel one day and the 55gal tank was full when I left the yard. mind you this was all Chicagoland driving.

Going to a 9 speed with a slower OD will allow the engine to not work as hard but it drops your max MPH down to 54MPH (at 1800RPM) and you would want to turn the pump up anyways. Also that Mack 9speed with 5.73 rears will have you some very short gears on the low side. I would think that the low side would have a few redundant gears but the high side would better suit your needs. 4.42 was a common rear gear for the 9 speed.

I should also mention that the 9 speed mack had range selector clutch pack issues. there were revisions made to them thru the years

 

 

Trent

[Outbehindthebarn]

I've never run a 5 speed Mack, but opinions on them seems to be all-over-the-map... I've read more than once, I'm certain, at how strong and competent that 300 5 speed combo was... driver friendly etc... even at full weights (or so I was led to believe) ... Then there's the problems the OP has. I've met more guys who hate 5 speeds than guys who love them. Always a curiosity to me. The only Mack trans that receives universal praise is the vaunted 12 speed.

 

[Kenny_dodge98]

Is there a mack trans thats got a top gear close to the 5 speed

[Lmackattack]

I think The 9 speed is the closest at .71

 

 

[1965]

1 hour ago, Outbehindthebarn said:

I've never run a 5 speed Mack, but opinions on them seems to be all-over-the-map... I've read more than once, I'm certain, at how strong and competent that 300 5 speed combo was... driver friendly etc... even at full weights (or so I was led to believe) ... Then there's the problems the OP has. I've met more guys who hate 5 speeds than guys who love them. Always a curiosity to me. The only Mack trans that receives universal praise is the vaunted 12 speed.

 

The way I see it; most folks are use to the multi-gear trans. quick shifting like driving a car; the 5 & 6 speeds stay in gear a lot longer, you can’t shift them fast, rpms go way down & most people think there not pulling & that they have lost all there momentum. Then on top of all that they can’t snort & clown between gears as good.

[Lmackattack]

I will admit that after being out of an R model for a while then getting into one  it takes a few stop lights to get back into the habit of letting the RPMs drop before grabbing the next gear. I also tend to pull it out of 5th looking for that next gear on the highway .  but they were the trucks I learned on and it comes back to you quick. I think the guys that have never driven a 5 or 6 speed mack but spent years with 13 speeds have it harder to grasp the shifting of them

[1965]

Exactly; I didn’t start out with 1; but after driving 1 I liked them & that’s what drew me to Mack cause they were in a class by themselves. Most people over wind rpms past there peak or don’t let them pull down to there sweet spot. It’s all about what your doing with the truck & or how it’s spec’d.

[Hayseed]

Speaking as someone who's put a few years in Driving a 285 Coolpower & a 5 Speed at 90 odd Thousand Pounds.

My advice is To just "relax & let It happen" & happen it will (you're already proving that).You just can't have as many Coffee & piss stops as everyone else But I bet your only a few Minutes (If any) behind every one else..

As being mentioned getting a gearbox with more gears will only give you more gears to Change,& hardly be worth the Time,effort, or Money (In my opinion).

Just rum It as is for a while then Upgrade to a later model truck down the. track..

 

Just My 2 cents worth..

[Maxidyne]

Good arguments for the Maxidyne, guys! Given that NC has an 80k pounds weight limit and the rig is probably running empty one way, best strategy would be to stick with the 300 Maxidyne and swap in a 6 speed low hole transmission if more gear reduction is needed.