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Discussion Starter #1
Can someone post the gear ratios for the 6sp?? 'Been looking around the site and can't find any post with the numbers. Thanks ahead!

TT
 

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as per zf web site
1st 5.79
2nd 3.30
3rd 2.10
4th 1.31
5th 1.00
6th 0.72
rev 5.23
 

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Discussion Starter #3
Thanks 05. Funny, that's the same ratios as the Ford, except for reverse. The Ford stick knob says R-L-1-2-3-4-OD. Reason I'm asking is I'm seriously looking at ordering a new '06 Duramax LLY 6sp. I test drove a FORD PSD 6sp F250. Remember the old Ford slogan "Have You Driven a Ford Lately?" Well, I have. Yesterday. Been there, done that. Goodbye. All I can say is you gotta be a Ford loyalist to buy one....

Anyway, it was nice to shift thhru the gears on the diesel. I did notice that it didn't seem all that gutsy, at least at 50 mph. It felt like the power falls off fairly rapidly in the upper rpm range. How's the LLY handle with the 6sp? I did test drive a duramax/Allison also (like night and day...to the Ford). It was hard to get a feel for what the manual would be like. I'm going to virtually have to buy this truck "blind" as there are no manuals to be had.

All input from experienced handshakers welcome !
 

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Tettruck, whereabouts are you located? A local dealer here in OH has a manual tranny sitting on the lot. I drove it about 3 weeks ago and was very impressed. The gearbox is a little tighter than the 5 speed in my 1/2 ton, but it's still a basic H pattern. The Chevy shifter is designated R, 1-6. I was very impressed with the power since my previous diesel experience was behind the wheel of 7.3L IDI with a 5 speed. This truck has balls!!
 

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You will not be displeased! You can really fly thru the gears with these. The power and the smoothness of the shifting is amazing. I hope you can get to drive one before buying but I don't think you will reget buying one even if you don't get to before buying one. You will have to save up for a Flywheel in the future though. The stock DMF will not last and its for sure if you chip up the power. Good luck!!!

Nahan
 

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Anyway, it was nice to shift thhru the gears on the diesel. I did notice that it didn't seem all that gutsy, at least at 50 mph. It felt like the power falls off fairly rapidly in the upper rpm range. How's the LLY handle with the 6sp? I did test drive a duramax/Allison also (like night and day...to the Ford). It was hard to get a feel for what the manual would be like. I'm going to virtually have to buy this truck "blind" as there are no manuals to be had.

All input from experienced handshakers welcome !
That is pretty much the same case we all had. For me, it was order......sight unseen.
 

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Discussion Starter #7
You will not be displeased! You can really fly thru the gears with these. The power and the smoothness of the shifting is amazing. I hope you can get to drive one before buying but I don't think you will reget buying one even if you don't get to before buying one. You will have to save up for a Flywheel in the future though. The stock DMF will not last and its for sure if you chip up the power. Good luck!!!

Nahan
Uhm...and what would replacing the flywheel cost? For a non-warranty dealer replacement? How about an aftermarket? How many miles can I expect the original to last under "normal" use?
 

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No one really knows. I would have to say it depends on the driver. Mine lasted 30,000 with about 15,000 with the hypertech on 90HP and all mine did was start to slip but never had a rattle like most have. The slipping I think is still due to the DMF. I have an upgraded clutch disc now and it still slips like mad. I think there is too much movement in the DMF to allow the clutch to properly grab the flywheel. I will say GM will warrenty the flywheel till 100,000 due to the fact it is "part" of the engine. What that means is you can eat as many DMF as you want in 100K or till you get tired of it. Power is one of the biggest killers of the DMF I think. Sorry for the downer but I wanted to be turthful with you. Other than that I would and will never take back buying it. Like said before almost all of us bought blind due to the are very few out there. As far as replacements Evan at Crank-it-up-Diesel sells 3 kits and SBC sell one and are going to have another kit here soon so you at last have options which is something none of us have had till a little while ago. Peter, Wade, John, Evan and maybe others I don't know of sell the SBC kits. Right now you looking at $1800 to $2500. SBC are coming out with a cheaper SDC kit. Don't know of the price but I think it could be around $1000. There could be a cheaper one out there I don't know of.

Good Luck
Nathan
 

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Discussion Starter #9
Thanks for the reply. It'll keep me thinkin.... Can you tell what your RPM is at 60mph? And with what tire size, also.

I just got back from three test drives:

GMC 2006 D/A
Chevy 2006 D/A LT3 loaded
Chevy 2006 6.0L gas with 5sp manual.

I have to say, the duramax sounds nice, but seems "heavy" or sluggish, at least until you hit that certain power band. The gasser drives as expected, peppy, with good range of power and torque. Wish it came with a 6sp manual instead of the 5sp.

Also, it seems like the diesels ride a bit bouncier. Could that be due to the extra up front weight of the engine?

Thanks to all for your replies !!

Wonder what the mpg would be for the 6.0L gasser....
 

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Wish it came with a 6sp manual instead of the 5sp.
The 8.1 does, but I don't know if you want that big of an engine. The 5 speed will be fine, but the ZF6 sure is nice.
 

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I have to say, the duramax sounds nice, but seems "heavy" or sluggish, at least until you hit that certain power band. The gasser drives as expected, peppy, with good range of power and torque. Wish it came with a 6sp manual instead of the 5sp.
The power on a diesel does come in different than an a gasser. On my truck around 10k miles, the engine seemed to seat in and my power and mileage went up. At around 95k the power seemed to come in again as the engine continues to limber up.

I would race my wife in her '00 Tahoe and my 2500 bone stock...she would barely pull away from me. Not to bad considering the weight difference. Now...when I put the VA on, set at 110, I literally left her Tahoe in the dust (or should I say smoke :)) With the VA there is no comparison between the diesel and gasser...diesel hands down. But when you play you have to pay. I'm now needing a new clutch and waiting for SBC to complete the single disk, single mass flywheel setup.

MaxRock
 

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Discussion Starter #12
So, you guys with sixers, how do you handle the turbo lag? Or, maybe you can't feel it as much with the manual as with the Allison ...??
 

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it is still felt

you can feel it kick in about 1800 RPM it is a burst of energy. I don't think it is as noticable but there. Still drives great compared to a 6 speed 7.3 or 6.0 Ford
 

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Discussion Starter #14
So, in upshifting thru the gears, with the diesel being a lower rev engine and with a shorter rpm range, is it just more shifts with shorter rpm range, especially when the turbo kicks in? Maybe you skip a few shifts? Sorry for my questions here, but if I get this truck, it'll be my first diesel. I am plenty familiar with gas manual shifters, so I'm trying to relate to what the diesel will be like.

When I drove the Allison in ""M" and tromped on it, it was kinda like:

whooaaaaaaaaWaaaaaWWWWAAA!!! (Then gotta shift it or the govenor kicks in).
 

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If the truck is empty you can easily do a 2-4-6 shift. If you are getting on it, empty, you will not stay in the lower gears long. If you are not careful you will be up against the govenor in a heartbeat. Just a little practice and getting use to the truck will take care of this. Once you get into 3rd, in my opinion, the truck reallly starts to pull. 4th, 5th and 6th are pretty close together and can keep the engine in the torque curve easily.

Hope this helps.

MaxRock
 

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@ 60 I think mine is right at 1700-1800 I think with my 265/75R16 31.5" tall according to goodyears web site. Everything else is the same as yours will be. ?'s are no problem. Chips help with turbo lag and they also help build alittle more low end power and boost to.
 

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If the truck is empty you can easily do a 2-4-6 shift. If you are getting on it, empty, you will not stay in the lower gears long. If you are not careful you will be up against the govenor in a heartbeat. Just a little practice and getting use to the truck will take care of this. Once you get into 3rd, in my opinion, the truck reallly starts to pull. 4th, 5th and 6th are pretty close together and can keep the engine in the torque curve easily.

Hope this helps.

MaxRock

:exactly: I always skip gears its either 2-4-6 or 3-4-6. i honestly dont watch the tach so i cant say where i shift, just when it feels right i guess!!!

Caleb
 

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Thanks 05. Funny, that's the same ratios as the Ford, except for reverse. The Ford stick knob says R-L-1-2-3-4-OD.
That is because it is the exact same trans as in the Ford Super Duty.

Then only difference is that GM uses synth fluid and no trans cooler, Ford uses dyno fluid and a trans cooler.

Its a solid trans, for sure.
 

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Discussion Starter #19
Thanks to all for great replies. I feel comfortable with it. I worked out the rpm's on paper for 265/75/16's as 1710 @ 60 mph, with stock rear end. That matches you Duramax Farmer. I take it you're not feeling any real power loss as a result of the slighter net taller gearing??
 

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I don't think so. I bought the truck used and it already had 265s on it so I couldn't ell you about the power loss from 245 to 265s. I did run 285s for about 20,00 miles and I didn't see any loss in mileage but did find it harder to turn over the tires stock. I did a lot of highway driving for college so they helped to keep the RPMs down on the road and get better MPG but it didn't help or hurt any. When I finished I thought that in the hills and on roads with 55MPH speed limits back home, I thought that the 285s might bring the mileage down some so I when back to 265s but still saw no drop or rise in MPG. I could buy used 265s from work dirt cheap when we had them so I just snatch any that come in. 285s did look good on the truck.
 
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