Late August my 90,000 mile Z24 convertible Isuzu 5spd trans locked up in 3rd gear while slowly leaving a stop light.
Due to several home projects going on at the time I didn’t have the time to work on it. So I pulled it into the garage and left it sit for about two months. Early October I pulled the shifter linkage off to check for problems and didn’t find any.
Oct 13th I decided to take it to the dealer for a diagnosis before I started to tear it apart. $95 later they confirm its an internal trans issue. They wanted $3,500 for a new Isuzu, $2,800 for a rebuilt. Called my local AAMCO shop and they wanted $650 to tear it out and determine the problem plus additional money to fix it once they identified it.
I get on this board and ask what to do. Several folks convince me that the NVG swap is the best bet. I’m pretty mechanically inclined so after some reading I decided to go for it.
I find an NVG trans for $350 and pick it up but it doesn’t have the front mount.
Oct 24th Mark (FAST2.4 P) comes to my rescue and fabs up a front mount, a shifter cable mount and some other various parts (seals, washers, bushing, etc). Since this is the prototype it takes about 3 weeks to get here.
I decide to get a jump on things and remove the trans. The first few gotchas appear. I have the car about 20” off the ground when I attempt to remove the axle nut (30mm deep socket) Trying to get it off with a ratchet won’t work since the other wheel will just spin so you need to either get some weight on the other wheel or use an impact wrench. Fortunately my impact has enough oomph to get the nut off. On to the next issue, removing the axles. After a little deliberation I decided to leave the hubs in place and push the axles in bending the cv joints and prying the axles out with a large flathead screwdriver/pry bar. Works like a dream!
Now onto dropping the trans no real drama here except for physically getting the trans out once everything was disconnected. Even with a trans jack its tricky dropping it out the bottom due to the lack of space and the awkward weight distribution of the trans. All in all pulling the trans took about 3 hours. Luckily I decided I would bag and tag every bolt in a zip lock “snack size” bags. This came in very handy since it would be nearly 2 months before I got everything back together!
Nov 10th; Since the stock clutch had 90k miles I decided I should replace it while I’m in there. I ordered a LUK z24 clutch kit for $235, which arrives 2 days later. 1st big issue, the slave won’t work with the NVG trans. I look it up and the slave alone is $140 after some deliberation I decide to return the clutch kit and get one for a Berretta GTZ. 2 days and $255 later the clutch kit arrives. The slave fits fine but the clutch and friction disc will not fit the Z24 flywheel. I order a new Berretta GTZ flywheel ($90 minus a $40 core) the Tues before Thanksgiving and it was to arrive Fri. Nov 28th. I went to the auto parts store on Fri and no flywheel! They didn’t place the order for some reason so I had to wait another 3 days.
While the NVG trans is sitting around. I decided to replace the output shaft (axle) seals. I rented the install tool from my local AutoZone and proceed to ruin 4 seals before determining that the install tool is damaged and that was what was causing the seals to get ruined. In the end I returned the tool and got another one, which worked, but this ended up causing about a week delay. Since time to work on the car is at a minimum, I decided that I could get the trans in and put the drivers side seal in later (BIG mistake)
Finally the flywheel, clutch, and slave were ready. I mounted it all up in about 2 hours them and got ready to put the trans in. All went well until I tried to get the trans in. After fighting with it for over 4 hours I determined I’d have to trim the subframe with a sawzall. I tried lowering the cradle and it didn’t help. Literally, after 45 sec with the sawzall, I trimmed a small piece of the subframe and the trans fits right in. I started to bolt things up and realize there are far fewer bell housing bolts on the NVG than the Isuzu (4 fewer I think).
Now the fun began. The front mount Mark made fits great and makes things a hell of a lot easier. The rear mount needed to have its top two holes enlarged with a ½” drill bit since the NVG uses M12 bolts not M10 like the Isuzu. Fortunately I was able to reuse one of those left over bellhousing bolts for the trans mount. The problem? I didn’t look at the mount and the trans until it was in the car so I had to pull the mount out again to do this. Remember that output shaft (axle) seal I had to replace on the driver’s side? Took about 2 hours of tinkering to get it back in with the trans in place!
The splash shield from the Isuzu doesn’t fit the NVG without some modification. I trimmed up a few parts and got it to work by using a little wire to hold it on.
Dec 14th
On to the shift cables. After installing the trans I realized I would need to swap over the shift cable stubs from the Isuzu to the NVG which is no easy matter with the trans in the car. The cable bracket mount and extension Mark provided are beautiful pieces with tight tolerances and work great. The trick is to get the angle of the cables right you need to add washers to get the height of the cable mount bracket right. Again, no easy feat with the trans in the car. The shifter and trans need to be in neutral in order for the alignment to work. After messing with it for about an hour I give it a try. The trans is shifting! I took a break for dinner and came out to button the car up and what happens? I couldn’t shift the trans into any even gear (2,4,R) After looking into it for about 30 mins I realize the stock shifter cable has separated from its outer sheath. I call my local dealer and they want nearly $300 for new cables. Again Mark comes to my rescue and gets me the cables at a far more favorable price and has them shipped overnight to my house.
Now I have to put the cables in which in and of itself is not that big of a deal however due to the location of the car (close to the garage wall and in the air) I couldn’t easily remove the interior carpet and other accessories. So a 2-hour job turns to 5+ hours. Finally on Sat Dec 20th I get the cables attached and to my surprise everything works flawlessly! It’s a Christmas miracle. That night my wife popped open a bottle of champagne and saluted my successful one-man, bottom up transmission replacement. I hope to hell I never have to do that again!
A huge thanks goes out to Mark for all his work getting the NVG mount and cable bracket made, I would have been SOL without it since no junk yard bothers keeping them. Mark also went out of his way several times to help answer questions and offer solutions and I’m sure he is as glad as I am that I’m done!
damn, with my luck I will probably run into some bs as well. Good to see you finished it though.
That sucks. When my #3 rod bearing went the car would have the same power just knock. Its a very well built motor. The #3 rod bearing is just weak. if it wont go into gear though I would think its a loose flywheel. Did you RED locktite the bolts? Did you use a centering device on the clutch?
http://www.overkillengineeringmotorsports.com/
I used the centering device and blue loctite. I'm calling LUK this morning for ideas....
Humm, might be casue of the blue loctite. I know that my flywheel sounded just like a rod bearing. I took the tranny off and the flywheel bolts were 2 threads from falling off and they came out with me just using my fingers. There is a way to check it, start the car and press on the clutch, if it goes away even the slightest bit its the tranny.
http://www.overkillengineeringmotorsports.com/
I just got off the phone with LUK support. They don't have any ideas (go figure). Looks like a long cold weekend in the garage for me
Well got the trans off and found a snapped flywheel bolt. Guess I should have used RED loctite instead of blue. Of course noone has the flywheel bolts in stock and the GM dealerships are closed so other than getting that broken one out I guess I'm done for the day.
Hopefully thats it and I can get this thing back together.
I feel for you bro! I'm going to have to be droping my 4-speed Auto Thursday and Friday. I really would like to swap subframes from my car outside under a cover with 4-5" of snow on top and around it.
So I myself will be in a small garage droping an auto trans... I need to deside if I want to back the car in or just pull it in. I think I'm going for the pull in to get away from the cold garage door and the 10 to 30deg weather.
Great no one locally carries the bolts, 3~4 days minimum!
Well I searched this site to find that ARP #254-2801 bolt should work. Called ARP to confirm and they said it should do just fine but may be a mm or two long. Running down to Summit Racing after work to pick them up. $42 after tax but I should be able to get the car running again tonight or tomorrow.
Sounds good. Just remember to tighten them down evenly. By this I mean do like 5# increments so that the flywheel is on there perfectly. Also use RED locktite. Once you do those few things and tighten it all back down you should be good to roll. I just hope this is it with the problems.
http://www.overkillengineeringmotorsports.com/
Konrad Emrich wrote:
Dec 14th
On to the shift cables. After installing the trans I realized I would need to swap over the shift cable stubs from the Isuzu to the NVG which is no easy matter with the trans in the car. The cable bracket mount and extension Mark provided are beautiful pieces with tight tolerances and work great. The trick is to get the angle of the cables right you need to add washers to get the height of the cable mount bracket right. Again, no easy feat with the trans in the car. The shifter and trans need to be in neutral in order for the alignment to work. After messing with it for about an hour I give it a try. The trans is shifting! I took a break for dinner and came out to button the car up and what happens? I couldn’t shift the trans into any even gear (2,4,R) After looking into it for about 30 mins I realize the stock shifter cable has separated from its outer sheath. I call my local dealer and they want nearly $300 for new cables. Again Mark comes to my rescue and gets me the cables at a far more favorable price and has them shipped overnight to my house.
So I am in the middle of doing this swap right now and am running into similar issues. I have it all together and buttoned up but all the gears shift hard and reverse just doesn't happen. You mention that your had to shim up the cable bracket? Could you explain better how to do this or what the goal is? Better yet does anyone have pictures of the installed, working shift cable extender? I bought the transmission from the junkyard and am really hoping theres not something internally wrong...
If you can move the shift linkage then the tranny should be in good shape. I have noticed that with these trannys, unless it was raced everyday, they dont break. You need to shim the shift cables so that the cables are able to move freely. What I mean by this is, when you look at the cables they should not be bent or twisted at all. I think I have 7-8 washers under my cable bracket. Even the smallest amount of rubbing will cause premature failure of the cables and you will barly be able to move the shifter into gear.
http://www.overkillengineeringmotorsports.com/
EnviouZ wrote:So I am in the middle of doing this swap right now and am running into similar issues. I have it all together and buttoned up but all the gears shift hard and reverse just doesn't happen. You mention that your had to shim up the cable bracket? Could you explain better how to do this or what the goal is? Better yet does anyone have pictures of the installed, working shift cable extender? I bought the transmission from the junkyard and am really hoping theres not something internally wrong...
If you got the bracket from Mark (Over Kill Engineering Motorsports) all you need to do is put a stack of washers under each of the 3 bolts. I ended up needing a stack about 5/8" high on each bolt.
I got mine wrapped up last night around 11:30 PM and it seems fine. Haven't driven it yet but it seems the ARP bolts did the trick!
read the haynes manual as well... it says to torque down the flywheel bolts to a certain ft lb... AND turn it another 3/4 turn or something...
I believe I can see the future... as I repeat the same routine....
I torqued them down according to the GMSI (GM Service Information) instructions. I believe it was around 20 nm, +90 degrees but don't quote me on that.
Yep drove it today. Its fine except the clutch release point is a little high. Thanks for all the help Mark.
On the plus side, now that I know what I'm doing it only took 4 hours to get it back together! I could have cut about 45 mins off that time if I labeled the bellhousing bolts when I took them out. Not only do they have different head sizes (16 and 18 if I recall) they are different lengths and aren't really interchangeable!
My father was up top putting them in and I don't know how many times we would get one in only to find out it was the wrong bolt!
Okay not to thread jack but maybe you guys can help. I cannot for the life of me get the car to engage first and reverse. I can adjust it so that I get all the regular gears but no reverse or I can get reverse and lose 1 and 2. I think it may be to do with the B&M short shifter. Does anyone else have the B&M and the NVG? did you have any problems or anyone have any ideas?
Yep, I am running a 95-99 short B&M. You need to modify the shifter in the car to make it work. I can post pics. But its a pain in the butt. There is alot of fine tuning involved with the NVG kit.
http://www.overkillengineeringmotorsports.com/
Crap, I was afraid you'd say that. If you could post pics that would help a lot. Both for myself and for all the future swappers..
Thanks
