I was really hopeing someone would chime in here with their experiences. This seems like it would be a great thing to do. The 6.5 has plenty of power, it could really use the 6th gear at highway speeds. Imagine the fuel mileage you could get.
Umm would a gear vendor overdrive accomplish the same thing and be an easier install, a 6 speed could be installed but controlling the electronics could be tricky. I've never done either myself so looking for input as well
TD, I was thinking of the Gear Vendors Overdrive as well but a few guys that posted on here and were not happy with the results. They were burb owners iirc and they both had a vibration at approx. 40 mph that could not be resolved.
Wasn't there a six-speed 4l80e kit out there for a while? It gave the option of OD in each gear IIRC. Thought it would be cool if someone integrated that shift pattern into their programming. Throw in paddle shifters for the steering wheel...
Ah, no, I have never bolted a six speed to a 6.5TD.
The ZF6 will physically bolt onto the motor, but you'd have to figure something out for a clutch and possibly starter. You also wouldn't get much of an overdrive benifit since the 4L80E and NV 4500 are already and overdrive transmissions. The best would be a gearvendors. It would probably be cheaper and easier in the long run.
Your best bet is to go with a gear vendors over under auxillary drive. Done right it is awesome!!
The gv is used in corvettes for performance.
Had one on a motorhome and let me tell you the diffrence was incredible.
Wasn't anything it wouldn't out run up the hills.
Dad currently has one in his 2000 or 2001 Dodge 2500 cummins. When he takes of ya better be ready or your head gonna get slammed to seat.
Once I get some other mods done(air box and exhaust) then I am planning on putting one in my truck.
I also heard that if you try and put in the six(allison) you have to do a lift.
lot cheaper to go with the gear vendors. Go to a reputable place and everything should be fine. Place my dad went even redid the driveshaft and balanced the drive shaft. I think this may be why others get vibrations is the shop didn't balance the drive shaft right.
The 6 speed won't give you a higher top gear than the 5 speed, but it packs the gears that I use the most closer together, 2-3-4 on the 5 speed and 2-3-4-5 on the 6 speed. Gear vendors is nice, but not going on this one, wheelbase is too short.
Is the GV OD kit what I sat that bolted to the back of the trans? I've always heard of them being called a double overdrive kit or "Doubler". You just take off your taleshaft and bolt this on. Guess you have to run extra linkage too.
I also asked Q's about bolting up a 6 speed to a 6.5 over in the ZF6 forum. If you are interested, the title is "Bolt Pattern". I can't remember if there is any more info than is listed here.
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