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95 SUBURBAN to a 01 DURAMAX/ALLISON

Nick 6.5 said:
they are selling new mounts on ebay they look pretty slick. i was planning on saving money by keeping my 4l80e tranny and just building that to the nuts(race spec 600hp) and trying to wire the engine as a stand alone system. there's a shop out here in cali that will convert both your harneses to work with wutever combo you choose to use so i guess i just have to decide on that. The core support and intercooler i could handle no problem. like i said mainly just fitment of the axle/crossmember/firewall is what i was concered about, and u pretty much answered that for me. Thanks for all the detailed info and pics u showed on this thread and swap i know it helped me and probly alot of other guys as well!
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Remember a 600HP race engine will not have even the torque of a stock LB7 DURAMAX, and torque is what kills the trans. Personally I opted for the ALLISON because I didn't want to have to fight with a trans that was borderline of holding up. I know Malibu re-used his, and I have been impressed with how his has held up. But even he has had issues with it, and he drives OTR towing with some pretty tall gears. And if your talking about PPE to do the harness, they get $1200 to convert it over for you. Theres quite a few other places that will do it for ALOT less money, OR you can do it yourself as it isn't that hard to do in all honesty. I know there was a guy on ebay doing them, but I wouldn't let somebody who wires a an inline fuel pump to the transfer pump circuit do a harness for me.
 
ok ya i understand what your saying about the motor mounts, But what i was saying was adding the 350/454 mount for the stock gas engine in these 89-99 suburban/silverado trucks to the duramax mount, then for shits and giggles welding that> it basically takes all the guess work out of it. i know the torgue is what kills the tranny but im not going for an all out duramax id be happy with roughly 450-500hp to the wheels that would be perfect for my application. and yes i was talking about PPE. in your pictures from the thread it seemed to be pretty complex and painstaking, which for me wiring is 1 of those subjects i have little to no patience for. My buddy is pretty handy tho so maybe he can tackle it.
 
The 350/454 uses the same style mount as the 6.5L does, so it wouldn't do you any good. You would end up having to build custom mount pads on the frame to use the Ebay mounts and old style motor mounts. 450-500HP from a DURAMAX is ALOT for a 4L80E to handle in a heavy truck. And don't let anybody fool you, the older GMT-400 will weigh more than the newer trucks once you do the swap(my BURB weighs in right at 7,000 LBS with 1/2 tank of fuel). Malibu did his 4L80E in at less than 300HP. He does tow heavy ALOT, but he also has tall enough gears he is turning around 2400 at 70 I believe he said, and that lessens the load on the trans ALOT! Can it be done, yes. Will it last at 450HP and 7,000 pounds when you romp on it, that's a crapshoot(and if it does, for how long).
 
Nick 6.5 said:
ok pooint well taken! i have been finding alison 1000 for around 1000$ so i guess ill just pick 1 up
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I STRONGLY recommend getting a COMPLETE donor as all the little pieces you will need will cost more than the donor truck will. And in the end you can sell the donor truck to recoupe some costs.
 
id love to pick up a donor truck but every1 wants way too much around here and all the dismantlers get into bidding wars for them. although i have found a couple combos with compl;ete wiring for a couple thousand
 
Why not spend the cash and put in an optimizer or better yet a P400 probably costs about the same and all you really need to do the P400 is modify the oil pan.
 
there is one major thing different between my 4l85 and yours mine has straight cut gears vs helical gears. Josh harris is pushing a van setup @5500lb into mid 11s with power pack clutches34 sprag billet input and intermediate shafts and billet tc. i have stock4.63:1 gears it takes mathematically alot of work off the tranny... there are couple reason why i left the 85 in tailshaft parking brake less stuff is messed with and less downtime less money spent
at 350-400hp a modestly built 85 wont have a problem. and will move a 7500lb truck rather nicely. my truck weighs7300lb even
though it is short legged (od is roughly same as Allison in 4th) it moves very nicely . the only thing i miss is the gm low stall 1500rpm tc its been replaced by a 2000stall.. dont really notice the difference till you do stop n go with 17,000lb hooked to the back. it takes more throttle and time to get the load moving with the 2000 vs 1500
the two repower i plan are getting 85s 75k20 and .y 79 malibu the . if i did my 99 over again i'd do Allison... why outside power capacity it has better gear range. i could run a 5 speed drop to 4.1 from 4.63 in crease off line and Lowr cruise rpm by ~600 romm
 
ferm.
outside sprag failure and tcc failure at 197/203k both of which have been known to happen in less harsh environments.i wouldn't say i've had issues due to power or weight that happens in normal setups
 
My 94 dually crew cab long bed had the 4l80 and it weighed 7400lbs, granted it didnt have the same weight but it did well with towing heavy loads
 
Sorry to be bugging u again about ur swap but i have just a couple more questions maybe u would be willing to answer? i just bought a 2001 donor truck and am finalizing everything for the swap. i was re-readin the thread and my only concerns are the wiring for the engine. did u basically just wire the engine harness to be a stand alone system for the dmax/allison? or did u fully integrate it to the 95 harness?
 
Nick 6.5 said:
Sorry to be bugging u again about ur swap but i have just a couple more questions maybe u would be willing to answer? i just bought a 2001 donor truck and am finalizing everything for the swap. i was re-readin the thread and my only concerns are the wiring for the engine. did u basically just wire the engine harness to be a stand alone system for the dmax/allison? or did u fully integrate it to the 95 harness?
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It's basically a mixture of the two. All of the systems in the 95 work as stand-alone to start with, so I made the DURAMAX/ALLISON combo stand-alone from the rest of the truck BUT I wired it into the 95's fuse panel's like factory(only had to add in 2 or 3 fuses IIRC, and 1 relay). Also I hooked up the ECM's outputs for the speedo and ABS and eliminated the VSSB behind the glove box in doing so. I then added in an extra wiring harness that I made for tow/haul, OD/LO, and DSP switches as well as tow/haul and OD/LO indicators. Wiring is where it can get tricky as there is so many different ways of doing it depending on how you want it to work. I wanted mine to work like factory with as little added in as possible, but I didn't want to have any electrical gremlins so I employed the KISS method while doing it(keep it stupid simple). The hardest part was opening up the whole harness from the ECM over to the underhood fuse panel and eliminating everything I didn't need9 but keeping enough to integrate the DURAMAX/ALLSION and make it all work like stock. I spent a good 40 hours sitting down going over wiring diagrams for both vehicles and figuring out which wires to cut and which to keep, and then doing it all over again when a problem with my original plan arose.
 
ya id like to have it work and look factory as much as possible. the other thing is my truck is 96 obd2 so i think any tips and tricks i learn from u wont work for my truck. im good at mechanics and fab work but wiring im not good at at all so im just a little bit worried about that.
 
I have read virtually everything you have written about your Burb. I am in the middle of converting my 99Tahoe into Durahoe. The donor truck is a is a 06 GMC Sierra 3500 WT that was pretty much rolled into a ball. It is a LBZ with the 6spd Allison. I am pretty much bolted down (using your thread and Jim Bigley's book) I'm at the point of being stumped about some of the wiring. I am using the 06 wiring harness, instrument panel, and steering column with the 99 dash. My problems arose in trying to use the other controls from the 99. In my reading, I think the AC controls either go hot to ground, or is it ground to hot, or is data in cold air out or am I going to ride with the windows down??? Wait a minute---I can't get the power windows down (or up). Maybe if I turn the radio up, it will all smooth out. Wait another minute---It does like the wiring either! maybe if I could shed some light on the subject---no luck there. I guess I need some serious psychological work---or the truck needs to be made functional.
Is there a way to get the things that the BCM handled on the 99 to talk to the 06 harness? If you have any answers , I surely would appreciate some help. Please be pretty simple with any answers because I am not too sharp.
 
nefes said:
I have read virtually everything you have written about your Burb. I am in the middle of converting my 99Tahoe into Durahoe. The donor truck is a is a 06 GMC Sierra 3500 WT that was pretty much rolled into a ball. It is a LBZ with the 6spd Allison. I am pretty much bolted down (using your thread and Jim Bigley's book) I'm at the point of being stumped about some of the wiring. I am using the 06 wiring harness, instrument panel, and steering column with the 99 dash. My problems arose in trying to use the other controls from the 99. In my reading, I think the AC controls either go hot to ground, or is it ground to hot, or is data in cold air out or am I going to ride with the windows down??? Wait a minute---I can't get the power windows down (or up). Maybe if I turn the radio up, it will all smooth out. Wait another minute---It does like the wiring either! maybe if I could shed some light on the subject---no luck there. I guess I need some serious psychological work---or the truck needs to be made functional.
Is there a way to get the things that the BCM handled on the 99 to talk to the 06 harness? If you have any answers , I surely would appreciate some help. Please be pretty simple with any answers because I am not too sharp.
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Your going to have to convert it to 03+ style wiring to make it work like your talking about. The 01-02 DURAMAX used the same basic wiring setup as the 95-00 trucks did and was one of the reasons I chose the early LB7. The A/C controls you have now will most likely never work as I believe the 03+ is pretty much all handled via databus. Your going to have to go in and do some stand-alone wiring to make everything work properly with the 06 wiring. Can't be of much more help as what you are doing is night and day different than what I did since I stuck with similar wiring architecture.
 
Have a bit of a carnage update. I've been fighting a leak at the transfer case output shaft now for awhile. Here recently I put it up on jackstands, and put it in gear. Watched the driveshaft, and it looks like I have managed to bend it. No signs of hitting anything, but it had a good 1/8-3/16 of out of roundness to it spinning it on jack stands just to the rear of the center of it. So the shaft is sitting at a shop to be checked out, and I will probably be getting a new 4 1/2" aluminum built to replace the 3 1/2" steel it had in it.I also found out that I had a screwed up shaft to begin with. I had the shaft from my donor truck retubed to the correct length for my swap, put in a new 1410 pinion yoke, and a new 1410 slip yoke for the transfer case. My shaft had the 1415 ends on it which are meant for a .010 narrower u-joint(thanks GM for using a joint so close to a standard readily available off the shelf part, but enough off to cause MAJOR head aches), and the shop that did the retubing used 1415 joints. So it was loose in the pinion yoke slightly, but tight at the slip yoke since I replaced that joint when I did the slip yoke. The shop that did y shaft origanlly wanted $325 for a new one, so I found another shop that would do it for $280, or for $400 would build me a 4 1/2" aluminum one. So I will most likely go back with what I should have done to start with.

Also I've had a rattle in the drivers side front for a year or so now(about the same time my drivetrain vibration started, right after I took it to the track), and I finally found it. Turns out one of the support bars that goes from the side frame rail to the front crossmember in front of the diff had broken on the drivers side. So now I have to move the lower radiator hose, pull out the airbag wiring, shield the brake line, and reweld the support bar in place. I guess the old saying ye who plays pays is panning out for me right about now.
 
Finally got a chance today to drive it with the new 4 1/2" aluminum shaft on interstate, and all I can say is it is SMOOOOTH! I wish now I owuld have spent the money back then for the aluminum as it was more than worth the money for the smoothness difference. BUT then my KENNEDY pump quit working on me:mad2:. So much for that 40,000 hour rated pump motor. It went to pulsing and growling so loud I thought my fan was coming off. It was literally shaking my running board from it locking up. So now I get to repalce the pump motor for that next week as it is a DOG without the lift pump running(not to mention SMOKEY!).
 
Replaced the lift pump motor/impeller assembly, installed a pre filter to hopefully keep this from happenign again, and installed a KENNEDY adjusteable boost valve to help clear up my hazing under WOT. All is right with the BURB again.
 
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