GMT900 408/80e conversion
01-30-2010, 12:17 PM
#41
Launching!
iTrader: (1)
Join Date: Jun 2009
Location: Washington DC/NoVa
Posts: 205
Likes: 0
Received 0 Likes
on
0 Posts
Hey Greg, which Caltracs setup did you use on your '07. I went to their site, but didn't find anything for the GMT900's. Did you just use a set for the 800's?
01-30-2010, 12:42 PM
#42
TECH Apprentice
Thread Starter
iTrader: (9)
Join Date: Mar 2004
Location: Denton, Texas
Posts: 343
Likes: 0
Received 0 Likes
on
0 Posts
I don't have any on there yet. I have my set on my 93 I will try to move over if possible. I've got to measure the spring length from the front bolt to the center pin, see if the hinges will move over and then order a new set of bushings to press into the 07 springs if it looks like it will work.
01-30-2010, 12:50 PM
#43
Launching!
iTrader: (1)
Join Date: Jun 2009
Location: Washington DC/NoVa
Posts: 205
Likes: 0
Received 0 Likes
on
0 Posts
Im very interested in seeing what you come up with for this, so if you don't mind, please keep us posted. I need Caltracs badly, and dont have the time or facilities to fab up some of my own. Good luck bro, glad to see youre modding up that nnbs, so I can see some insightful solutions :thumbsup:
01-31-2010, 10:25 AM
#45
TECH Apprentice
Thread Starter
iTrader: (9)
Join Date: Mar 2004
Location: Denton, Texas
Posts: 343
Likes: 0
Received 0 Likes
on
0 Posts
when I first got the truck I hated the way the DBW throttle felt. After the NP tune, the truck woke up and feels almost the same as cable driven, instant response. Didn't like how the G80 felt so it was pulled and the Truetrac was install. I miss not having an oil pressure gauge on the dash. The fit of the sound deadening material on the cab behind the drivers seat is shoddy but performs well. I have a rumbling in the front end after 47000 miles that I believe to be spindle bearings, taking it to GM next week to have it looked at for that. The bearings are covered in the 100k warranty, may be $100 deductible but we'll see. Fuel mileage, could never get mileage over 18 MPG even though I always ran 93 octane. Nothing that really sours my opinion of the truck. The 4.8L engine was impressive for how small it was.
02-01-2010, 12:09 AM
#46
Launching!
iTrader: (1)
Join Date: Jun 2009
Location: Washington DC/NoVa
Posts: 205
Likes: 0
Received 0 Likes
on
0 Posts
I have the oil pres gauge, not sure why yours wouldnt have one. Ive got some minor gripes about my truck, but overall, I really love it. That 4.8 is pretty damn impressive, cant wait to see what it does with FI and a six speed
02-27-2010, 10:17 PM
#47
TECH Apprentice
Thread Starter
iTrader: (9)
Join Date: Mar 2004
Location: Denton, Texas
Posts: 343
Likes: 0
Received 0 Likes
on
0 Posts
Finally started the 80e conversion section of the project. Damn, I need a lift in the worst way, my shoulder blades are raw from crawling around on my back under the truck all day. 
What all I had to do to pull the old trans out....
removed passenger side fender well liner to aid in the process
disconnect positive lead from battery
set e-brake and chocked the rear tires
removed front two O2 sensors for access to exhaust nuts
remove y-pipe from manifolds and muffler assembly
unbolt the shift lever from the trans and remove the shift selector switch and set aside
remove the u-shaped clip holding the shift cable to the bracket and remove cable from bracket
unbolt fuel lines mount bracket from driver side of case
unbolt 15mm nut at trans rubber mount on tailhousing. It is inside the access hole in the bottom of the xmember.
remove 4 21mm nuts at crossmember
put oil catch can under tailhousing and remove driveshaft
remove trans pan and drain fluid into catch tub. I use a large Rubbermaid so I don't miss a drop.
put the pan back on.
remove starter
remove convertor bolts
jack up crossmember to take the load off bolts and then remove the 4 bolts
lower transmission until the oil pan rests on the front xmember. trans xmember will fall off. Remove vent hose from trans xmember.
Use a wood block or plywood to protect the trans pan and jack trans assembly back up so you can remove the exhaust y-pipe assembly.
lower transmission back down
remove heat shield on passenger side
remove speedometer pickup wiring on tailshaft housing
remove large wiring harness on passenger side of trans behind heat shield by squeezing the sides
remove trans cooler lines, top is return, bottom pressure side. Slide plastic covers back and take a pick to remove the retainer wires inside the fittings to remove the hoses.
Using a 4 foot long extension and swivel, remove the three 13mm nuts holding the fill tube, vent tube and fuel lines brackets
Remove fill tube
place transmission or motorcyle type jack under transmission and put light support on the transmission.
Using a 4 foot long extension, remove all the 15mm bellhousing bolts. Lower bolts can be removed with a regular short socket setup.
Remove the transmission assembly and take care to not let the convertor fall off. A bolt into the convertor tab and mechanic's wire or zip tie to the inspection hole will hold it in place.
My 2002 80e has a transgo HD2 kit, vacuum mod kit and PI Vigilante 10" 3500 stall convertor custom built to mount to a standard truck/LS1 flexplate.
Install procedure so far...
Install convertor and make sure it's seated all the way. Tie it back using mechanics wire so it doesn't slip out. I put bolts in the cover holea and wired across the convertor lug to hold it in place.
I have a piece of masonite I place on the ground to slide the trans out or to put it under the truck to prevent scraping up the pan.
I used a motorcycle jack with plywood on it to install the trans. I had to use ratchet straps across from one side of the frame to the other to hoist it up high enough to get the jack under that heavy pig. Once under the trans I just jack it up to installation height. Getting the trans at the right angle is a little tricky when you're doing it by yourself, I use a ratchet strap from the jack up and around the tailhousing to pull it to same angle as the engine.
Install transmission as normal and check that the convertor has space between the flexplate and the convertor during install.
Tighten all the 15mm bellhousing bolts
install the vent tube bracket at the top center stud, 13mm nut and vent tube to the transmisson vent. Tube will be the stock rubber hose from the 60e.
install the fuel hose bracket to the top bolt on the left using one 13mm nut
jack up transmission to maximum height and install new 80e oil fill tube and secure with the last 13mm nut.
measure clearance from flexplate to convertor lugs. If greater than 3/16" then place appropriate thickness washers to get correct clearance. Use bolts supplied by convertor manufacture. Longer bolts will be needed if you have to use washers greater than 1/16". You may have to buy longer bolts and cut/grind to correct length.
Install convertor bolts loosely in all three holes and then tighten after last is installed.
install starter
lower transmission, again
install cooler fitting c-clips
stretch the bottom cooler line out by removing some of the bends to fit to the front cooler fitting.
The top line is the return line and needs to be cut and a piece of transmission cooler quality hose needs to be used to extend it to fit into the rear center support return fitting. I use two clamps per end to prevent possible leakage should one come loose. -AN compression fittings can be used along with braided hose rather than cooler hose.
slide the plastic retainer clips over the cooler fittings
install the shift selector switch on the driver side you removed from the 60e
the factory speed sensor can plug back into the 80e tailshaft sensor
Driveshaft mod...
removed the 60e slip joint. Hooray! The worktruck has a steel driveshaft and has 1.188 diameter joints, 1350s, same as my 80e slip yoke. No puney 1.06 or 1.125 1310/1330 size joints.
Have to pick up a new joint for it tomorrow so I can install the 80e yoke.
This is as far as I made it today.
What all I had to do to pull the old trans out....
removed passenger side fender well liner to aid in the process
disconnect positive lead from battery
set e-brake and chocked the rear tires
removed front two O2 sensors for access to exhaust nuts
remove y-pipe from manifolds and muffler assembly
unbolt the shift lever from the trans and remove the shift selector switch and set aside
remove the u-shaped clip holding the shift cable to the bracket and remove cable from bracket
unbolt fuel lines mount bracket from driver side of case
unbolt 15mm nut at trans rubber mount on tailhousing. It is inside the access hole in the bottom of the xmember.
remove 4 21mm nuts at crossmember
put oil catch can under tailhousing and remove driveshaft
remove trans pan and drain fluid into catch tub. I use a large Rubbermaid so I don't miss a drop.
put the pan back on.
remove starter
remove convertor bolts
jack up crossmember to take the load off bolts and then remove the 4 bolts
lower transmission until the oil pan rests on the front xmember. trans xmember will fall off. Remove vent hose from trans xmember.
Use a wood block or plywood to protect the trans pan and jack trans assembly back up so you can remove the exhaust y-pipe assembly.
lower transmission back down
remove heat shield on passenger side
remove speedometer pickup wiring on tailshaft housing
remove large wiring harness on passenger side of trans behind heat shield by squeezing the sides
remove trans cooler lines, top is return, bottom pressure side. Slide plastic covers back and take a pick to remove the retainer wires inside the fittings to remove the hoses.
Using a 4 foot long extension and swivel, remove the three 13mm nuts holding the fill tube, vent tube and fuel lines brackets
Remove fill tube
place transmission or motorcyle type jack under transmission and put light support on the transmission.
Using a 4 foot long extension, remove all the 15mm bellhousing bolts. Lower bolts can be removed with a regular short socket setup.
Remove the transmission assembly and take care to not let the convertor fall off. A bolt into the convertor tab and mechanic's wire or zip tie to the inspection hole will hold it in place.
My 2002 80e has a transgo HD2 kit, vacuum mod kit and PI Vigilante 10" 3500 stall convertor custom built to mount to a standard truck/LS1 flexplate.
Install procedure so far...
Install convertor and make sure it's seated all the way. Tie it back using mechanics wire so it doesn't slip out. I put bolts in the cover holea and wired across the convertor lug to hold it in place.
I have a piece of masonite I place on the ground to slide the trans out or to put it under the truck to prevent scraping up the pan.
I used a motorcycle jack with plywood on it to install the trans. I had to use ratchet straps across from one side of the frame to the other to hoist it up high enough to get the jack under that heavy pig. Once under the trans I just jack it up to installation height. Getting the trans at the right angle is a little tricky when you're doing it by yourself, I use a ratchet strap from the jack up and around the tailhousing to pull it to same angle as the engine.
Install transmission as normal and check that the convertor has space between the flexplate and the convertor during install.
Tighten all the 15mm bellhousing bolts
install the vent tube bracket at the top center stud, 13mm nut and vent tube to the transmisson vent. Tube will be the stock rubber hose from the 60e.
install the fuel hose bracket to the top bolt on the left using one 13mm nut
jack up transmission to maximum height and install new 80e oil fill tube and secure with the last 13mm nut.
measure clearance from flexplate to convertor lugs. If greater than 3/16" then place appropriate thickness washers to get correct clearance. Use bolts supplied by convertor manufacture. Longer bolts will be needed if you have to use washers greater than 1/16". You may have to buy longer bolts and cut/grind to correct length.
Install convertor bolts loosely in all three holes and then tighten after last is installed.
install starter
lower transmission, again
install cooler fitting c-clips
stretch the bottom cooler line out by removing some of the bends to fit to the front cooler fitting.
The top line is the return line and needs to be cut and a piece of transmission cooler quality hose needs to be used to extend it to fit into the rear center support return fitting. I use two clamps per end to prevent possible leakage should one come loose. -AN compression fittings can be used along with braided hose rather than cooler hose.
slide the plastic retainer clips over the cooler fittings
install the shift selector switch on the driver side you removed from the 60e
the factory speed sensor can plug back into the 80e tailshaft sensor
Driveshaft mod...
removed the 60e slip joint. Hooray! The worktruck has a steel driveshaft and has 1.188 diameter joints, 1350s, same as my 80e slip yoke. No puney 1.06 or 1.125 1310/1330 size joints.
Have to pick up a new joint for it tomorrow so I can install the 80e yoke.
This is as far as I made it today.
Last edited by Red Heartbeat; 02-27-2010 at 10:31 PM.
02-28-2010, 03:54 PM
#48
TECH Apprentice
Thread Starter
iTrader: (9)
Join Date: Mar 2004
Location: Denton, Texas
Posts: 343
Likes: 0
Received 0 Likes
on
0 Posts
Note to self: Dry winter grass burns fast when abrasive cutoff saw sends sparks onto it and the wind is about 20 mph. Cleaned up the dead grass between my house and the neighbors. Damn near wore myself out extinguishing the flames.
Modify the xmember by cutting off 5" from each end. Use 4" x 1/4" thick plate 11" long to move the xmember back to the mount location. Will get the measurement of how far I moved it back. Transmissioncenter.net shows it should be 6.781, just a little more than 6-3/4".
Okay, it ended up being 5-7/8" that I had to shift the mount toward the rear. I could have used about a 10-1/4" long piece. Everything is back in except the driveshaft, now to the wiring and tuning. Might be a while since we're expecting cold and rain over the next couple of days.
Modify the xmember by cutting off 5" from each end. Use 4" x 1/4" thick plate 11" long to move the xmember back to the mount location. Will get the measurement of how far I moved it back. Transmissioncenter.net shows it should be 6.781, just a little more than 6-3/4".
Okay, it ended up being 5-7/8" that I had to shift the mount toward the rear. I could have used about a 10-1/4" long piece. Everything is back in except the driveshaft, now to the wiring and tuning. Might be a while since we're expecting cold and rain over the next couple of days.
Last edited by Red Heartbeat; 03-01-2010 at 12:14 AM.
03-03-2010, 12:28 AM
#49
TECH Apprentice
Thread Starter
iTrader: (9)
Join Date: Mar 2004
Location: Denton, Texas
Posts: 343
Likes: 0
Received 0 Likes
on
0 Posts
finished the install today....
1.) Installed 80e slip yoke, no driveshaft modification needed other than a new ujoint.
2.) extended return hose from cooler to transmission using an old piece of steel transmission tubing and two 3/8" compression unions.
3.) found shift linkage I tossed in the storage unit and installed it. No modifications had to be made to the linkage or even adjustments to the cable.
Tomorrow will be test and tune after I install a vacuum tee in the brake hose for the Transgo 48mod unit I have in the transmission. I'm first going to modify the wiring harness to correct the wiring for the 80e. Need to split out wires for the input speed sensor, swap a couple wires in the round connect for the converter and update the tune for the taller 1-2 gear ratios and shorter OD ratio.
Factory gear ratios in the transmissions...
60e 3.059, 1.625, 1, .70
80e 2.482, 1.482, 1, .75
1.) Installed 80e slip yoke, no driveshaft modification needed other than a new ujoint.
2.) extended return hose from cooler to transmission using an old piece of steel transmission tubing and two 3/8" compression unions.
3.) found shift linkage I tossed in the storage unit and installed it. No modifications had to be made to the linkage or even adjustments to the cable.
Tomorrow will be test and tune after I install a vacuum tee in the brake hose for the Transgo 48mod unit I have in the transmission. I'm first going to modify the wiring harness to correct the wiring for the 80e. Need to split out wires for the input speed sensor, swap a couple wires in the round connect for the converter and update the tune for the taller 1-2 gear ratios and shorter OD ratio.
Factory gear ratios in the transmissions...
60e 3.059, 1.625, 1, .70
80e 2.482, 1.482, 1, .75
