zf 5spd towing

[hesutton]

I figured the 4th-5th gear jump would be worse at 76%

I rarely use OD when pulling the fifth wheel. I usually keep it in 4th and run at 2500. Better for EGT's and maintaining cruising speed in the KY hills. If I have a long flat spot, then OD will get a turn.

No matter how high I rev 3rd I can never catch 4th any higher than 2k. I take 3rd to 2500 and get 4th at 1500

The US Gear underdrive helps...... but I'll take it to 2700+ when getting the camper up to speed.

Heath

 

[gonecrazyi]

I have xmls and really like them. Need about 5-6 inches of lift to clear them. I have front springs from an f $superduty tow truck and can just clear them body wise.

 

[Diesel_brad]

I rarely use OD when pulling the fifth wheel. I usually keep it in 4th and run at 2500. Better for EGT's and maintaining cruising speed in the KY hills. If I have a long flat spot, then OD will get a turn.

The US Gear underdrive helps...... but I'll take it to 2700+ when getting the camper up to speed.

Heath

No OD? except on flats?

 

[hesutton]

No OD? except on flats?

Nope.

Heath

 

[Silver Burner]

I couldn't hardly use OD when I'm towing except on flats, mostly because I still have 3.55 gears.... I SOO want some 4.10's!

 

[Simp5782]

sounds good guys, i will look at the 4.10 gears... or there about,4.56s even, gonna take into consideration also i want to upsize in tires next fitting too, really looking at the 11.00/16 Michelen XZLs, look awesome and good traction off road.. just need a lil lift to clear them 1st...

You don't want to go the 4.56 route unless you are putting it to a towing test everyday and 5-6k is nothing for weight. My trailer alone weighs 8k. I am sure towcat will chime in here that with his superduty with 4.63s is SCREAMING at 60/65. I dont run my 85 with 4.56s and a 4spd over 55/57. I am towing a trailer everyday though. I get 11/13mpg empty turning 2700 at 55.

4.56s with 265's @ 70 with a ZF5 you will be right around 2600rpms in 5th. It you like feeling the vibration in the seat then go for it. You would be happy with 4.10s. You can find some 4.30s as well. It can be all about gears but you can help your engine as well. Just be prepared that I had issues in my 94 towing heavy loads with the DMF and I just broke the springs a few times so I went SMF.

Turn it up a flat or two. shorten your wastegate rod.Check out zagsters homemade propane injection kit. Or add an intercooler. I have the piping system for sale to make your own.

If you have manual hubs lock them in for driving around and lock it in 4H when you need to take off and what not and if its heavy and don't want to much strain on your rear driveshaft cause it could take a dump on ya.It also helps on pulling. I have taken the same hill with the same trailer and same load (3mi 7%grade)one in just 2wd non locked and once in 4H locked and I topped the hill 9mph faster in 4H locked than in just plain 2wd. I have been known to use 2L or 4L to get heavy loads on my gooseneck moving on steep hills and what not to take the strain off the tranny and driveshafts and kick out around 6mph just to get it rolling.

 

[flareside_thun]

You do realize that the tires he will be upgrading to are pretty much a 38 inch. 4.56's with 38's for towing wouldn't be bad.

 

[dizdak]

flareside- i was thinking they are in the 37-38" range, that is why i thought about 4.56s... i can't go too high with the truck cause of the gooseneck as well...
Simp - living in FL i don't have any real steep take offs, maybe some hills here and there but nothing major by any means, i do need to see about turning the I/P up if that is what you were referring to turning up a flat or 2.. i am learning this diesel stuff as i go, this is the 1st diesel i have ever owned..
the truck gets about 13mpg when hauling mid size loads (5-7k lbs), and much better when not loaded..

 

[RLDSL]

When I'm towing heavy, I never see 5th. Burns too much fuel. I usually stay in 4 over and it holds it;s own without me having to floor the thing. ( are you seeing a recourring theme here?? having the extra gears of an under drive/overdrive or Brownie really makes a world of difference in overall pulling ability
I still have 2 gears left to go when I'm empty

 

[Diesel_brad]

When I'm towing heavy, I never see 5th. Burns too much fuel. I usually stay in 4 over and it holds it;s own without me having to floor the thing. ( are you seeing a recourring theme here?? having the extra gears of an under drive/overdrive or Brownie really makes a world of difference in overall pulling ability
I still have 2 gears left to go when I'm empty

What gear ratio is 4th high?

 

[GOOSE]

The brownie is either .73 or .85.

http://www.6066gmcguy.org/spicer-5831-b.htm

 

[RLDSL]

What gear ratio is 4th high?

with a 4.10rear it ends up putting it about half way between 4 and 5 with roughly 500 rpm splits rowing the brownie

 

[Diesel_brad]

with a 4.10rear it ends up putting it about half way between 4 and 5 with roughly 500 rpm splits rowing the brownie

What does the rear axle ration have to do with the trans and Brownie ratio?

 

[RLDSL]

What does the rear axle ration have to do with the trans and Brownie ratio?

When you are trying to calculate where splits are going to wind up , throughout the entire range, you have to calculate it by the final drive ratio in each gear combination. This is the reason that brownies came in differing OD ratios , it's so that you could match them up. I did an insane amount of calculating when I began this project and I found that you can take one brownie with one od ratio and match it up against a 4.10, 3,70 3.55 and what ends up happening is you will only get fairly even splits with one and some will be so far out there it's not funny. You have to remember , the gear spacing on the zf is not even so some really strange things can start happening when you try to mix things up. The only way to find one to work at peak is to calculate each gear out to the final drive ratio and find the box that matches the closest

If you don't do this you wind up with some boxes where the split will be heavy to one side i.e. 750 rpms on one side and 250 on the other , but the goal is to find one that puts the splits as close to the middle as possible.

Somewhere in this mess of a computer , I have a file where I have basically all the available brownie combinations calculated out against all the common IDI rear ends, but I can't find the blamed thing

 

[redneckaggie]

OP where do you shift, I know so many people that believe that diesels shouldnt be taken above 2000 rpm and they are made to be driven on a "lug point" my dad will tell you exactly this but I have much better results movin my shift points on up to 2700-3000 and letting her roll. I dont remember the exact figure but someone one put a link to the r&d testing that these engines went through and it was all on the governer. the governer is in the ip for a reason, use it.