My experience with TH350 swap into 98 Z28
04-08-2009, 08:58 PM
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My experience with TH350 swap into 98 Z28 I am swapping in a trans braked th350 into my 98 Z28. Thought I would share the good, bad, and ugly..
1st issue: the left side middle bolt (the one right above the dowel) was a biatch to get in. It resides very close to the tranny hump/fire-wall. If I would have known this, I could have clearanced the area with a
instead I had to fiddle with 1/8 turns and an end wrench 
2nd issue: Lt1's have different cross members than the LS1's. I had purchased a used LT1 to 350 conversion cross member thinking they would be the same..NOPE. So I used my stock cross member and welded up a mount.
3rd issue: I was planning on keeping the stock shifter. But found that I did not like the feel. Since this is a reverse pattern, full manual, I wanted a more positive feeling engagement. I did read a write up about modding the stock shifter to give a better feel, but I had a TCI shifter already, so I went ahead and installed it.
4th Issue: Madman dipstick tube. Not sure if this one has been bent by previous owner or what, but it ended up under the cowl and angled slightly up. Which makes it difficult to get the dipstick with the lock to fully seat and lock. It also was a pain to wedge a funnel into it in order to fill the tranny.
Also would like to point out that 98 flexplates do have dual bolt patterns, but the ones used for the 350 converter do not have shoulders, just FYI.
All in all, I think I have all the worse behind me. I still need to wire up the transbrake, and sort out how I am going to do the interior with the after market shifter.
I hope this will help someone who is going to do the swap.
1st issue: the left side middle bolt (the one right above the dowel) was a biatch to get in. It resides very close to the tranny hump/fire-wall. If I would have known this, I could have clearanced the area with a
instead I had to fiddle with 1/8 turns and an end wrench 2nd issue: Lt1's have different cross members than the LS1's. I had purchased a used LT1 to 350 conversion cross member thinking they would be the same..NOPE. So I used my stock cross member and welded up a mount.
3rd issue: I was planning on keeping the stock shifter. But found that I did not like the feel. Since this is a reverse pattern, full manual, I wanted a more positive feeling engagement. I did read a write up about modding the stock shifter to give a better feel, but I had a TCI shifter already, so I went ahead and installed it.
4th Issue: Madman dipstick tube. Not sure if this one has been bent by previous owner or what, but it ended up under the cowl and angled slightly up. Which makes it difficult to get the dipstick with the lock to fully seat and lock. It also was a pain to wedge a funnel into it in order to fill the tranny.
Also would like to point out that 98 flexplates do have dual bolt patterns, but the ones used for the 350 converter do not have shoulders, just FYI.
All in all, I think I have all the worse behind me. I still need to wire up the transbrake, and sort out how I am going to do the interior with the after market shifter.
I hope this will help someone who is going to do the swap.
04-09-2009, 04:50 PM
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I am swapping in a trans braked th350 into my 98 Z28. Thought I would share the good, bad, and ugly..
1st issue: the left side middle bolt (the one right above the dowel) was a biatch to get in. It resides very close to the tranny hump/fire-wall. If I would have known this, I could have clearanced the area with a instead I had to fiddle with 1/8 turns and an end wrench
2nd issue: Lt1's have different cross members than the LS1's. I had purchased a used LT1 to 350 conversion cross member thinking they would be the same..NOPE. So I used my stock cross member and welded up a mount.
3rd issue: I was planning on keeping the stock shifter. But found that I did not like the feel. Since this is a reverse pattern, full manual, I wanted a more positive feeling engagement. I did read a write up about modding the stock shifter to give a better feel, but I had a TCI shifter already, so I went ahead and installed it.
4th Issue: Madman dipstick tube. Not sure if this one has been bent by previous owner or what, but it ended up under the cowl and angled slightly up. Which makes it difficult to get the dipstick with the lock to fully seat and lock. It also was a pain to wedge a funnel into it in order to fill the tranny.
Also would like to point out that 98 flexplates do have dual bolt patterns, but the ones used for the 350 converter do not have shoulders, just FYI.
All in all, I think I have all the worse behind me. I still need to wire up the transbrake, and sort out how I am going to do the interior with the after market shifter.
I hope this will help someone who is going to do the swap.
1st issue: the left side middle bolt (the one right above the dowel) was a biatch to get in. It resides very close to the tranny hump/fire-wall. If I would have known this, I could have clearanced the area with a
instead I had to fiddle with 1/8 turns and an end wrench 2nd issue: Lt1's have different cross members than the LS1's. I had purchased a used LT1 to 350 conversion cross member thinking they would be the same..NOPE. So I used my stock cross member and welded up a mount.
3rd issue: I was planning on keeping the stock shifter. But found that I did not like the feel. Since this is a reverse pattern, full manual, I wanted a more positive feeling engagement. I did read a write up about modding the stock shifter to give a better feel, but I had a TCI shifter already, so I went ahead and installed it.
4th Issue: Madman dipstick tube. Not sure if this one has been bent by previous owner or what, but it ended up under the cowl and angled slightly up. Which makes it difficult to get the dipstick with the lock to fully seat and lock. It also was a pain to wedge a funnel into it in order to fill the tranny.
Also would like to point out that 98 flexplates do have dual bolt patterns, but the ones used for the 350 converter do not have shoulders, just FYI.
All in all, I think I have all the worse behind me. I still need to wire up the transbrake, and sort out how I am going to do the interior with the after market shifter.
I hope this will help someone who is going to do the swap.
04-09-2009, 05:39 PM
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I already had an aftermarket torque arm, so I did not have to bother with a mount for the torque arm. I wish I had known that about the M6 cross member, but modding mine wasn't a big deal. After I had the tranny in, I mounted the cross member and tacked up a mount, then removed the cross member and finished welding it up.
04-09-2009, 05:50 PM
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Latest update:
I have everything in and transbrake wired. I am unable to really take the car on a test drive since it has open exhaust (turn downs off the headers). But I did test the transbrake, and much to my disappointment it will not hold over 3500 rpms. You get what you pay for..lol
I do have another th350 that I can rebuild with the right stuff and have it ready just to pop in when I get ready to change it. The other good thing is I have all the little stuff out of the way, so I will not have anymore surprises when I change it.
On another note, has any one else had problems with the madman dipstick being short?
I think I am, going to mod it to make it longer so that it will at least stick out from under the cowl like the original... I should be able to use my original tube and add to the madman tube to get it where I want it. Then I can use the original dipstick part to check the level.... just thinking out loud...lol
I have everything in and transbrake wired. I am unable to really take the car on a test drive since it has open exhaust (turn downs off the headers). But I did test the transbrake, and much to my disappointment it will not hold over 3500 rpms. You get what you pay for..lol
I do have another th350 that I can rebuild with the right stuff and have it ready just to pop in when I get ready to change it. The other good thing is I have all the little stuff out of the way, so I will not have anymore surprises when I change it.
On another note, has any one else had problems with the madman dipstick being short?
I think I am, going to mod it to make it longer so that it will at least stick out from under the cowl like the original... I should be able to use my original tube and add to the madman tube to get it where I want it. Then I can use the original dipstick part to check the level.... just thinking out loud...lol
04-09-2009, 05:59 PM
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I yea I have to use a wiggle socket, ( I call it a webble wobble..lol) to get to the top bolts. But this bolt hole is right beside the sheet metal. I could not even get the bolt to go into the hole with out having to pry the whole tranny/engine over to the side and while holding it over as far as I could, I had to muscle it into the hole. Once in it was able to clear the sheet metal, but there was no way in hell I could get a socket on it. It reminded me of the older model cars where you would have to use a hole saw to cut holes in the fire wall in order to get to the tranny bolts. I may have to do that to get the damn thing back out..lol
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04-09-2009, 06:08 PM
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Latest update:
I have everything in and transbrake wired. I am unable to really take the car on a test drive since it has open exhaust (turn downs off the headers). But I did test the transbrake, and much to my disappointment it will not hold over 3500 rpms. You get what you pay for..lol
I do have another th350 that I can rebuild with the right stuff and have it ready just to pop in when I get ready to change it. The other good thing is I have all the little stuff out of the way, so I will not have anymore surprises when I change it.
On another note, has any one else had problems with the madman dipstick being short?
I think I am, going to mod it to make it longer so that it will at least stick out from under the cowl like the original... I should be able to use my original tube and add to the madman tube to get it where I want it. Then I can use the original dipstick part to check the level.... just thinking out loud...lol
I have everything in and transbrake wired. I am unable to really take the car on a test drive since it has open exhaust (turn downs off the headers). But I did test the transbrake, and much to my disappointment it will not hold over 3500 rpms. You get what you pay for..lol
I do have another th350 that I can rebuild with the right stuff and have it ready just to pop in when I get ready to change it. The other good thing is I have all the little stuff out of the way, so I will not have anymore surprises when I change it.
On another note, has any one else had problems with the madman dipstick being short?
I think I am, going to mod it to make it longer so that it will at least stick out from under the cowl like the original... I should be able to use my original tube and add to the madman tube to get it where I want it. Then I can use the original dipstick part to check the level.... just thinking out loud...lol
04-09-2009, 06:22 PM
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It's not that the converter will not stall higher, it is that the brake won't hold above that, the car will launch while I am still hold the button. From what I read, this indicates a bad drive clutch or not having enough clutch plates to handle the motor's power. There is other possibilities also to do with pressure leaks, but I suspect the clutches.
04-10-2009, 01:24 AM
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I yea I have to use a wiggle socket, ( I call it a webble wobble..lol) to get to the top bolts. But this bolt hole is right beside the sheet metal. I could not even get the bolt to go into the hole with out having to pry the whole tranny/engine over to the side and while holding it over as far as I could, I had to muscle it into the hole. Once in it was able to clear the sheet metal, but there was no way in hell I could get a socket on it. It reminded me of the older model cars where you would have to use a hole saw to cut holes in the fire wall in order to get to the tranny bolts. I may have to do that to get the damn thing back out..lol
The TH350 first gear is a 2.52
