02 Tahoe tranny into 99 Tahoe

[CaptainChad]

I've been going at this project for a long time. Ive dropped and bolted up the tranny about 4 times, trying to figure this out. Im trying to put a 2002 4l60e (LS) 300mm tranny into a 98 Tahoe that had the (LT) 298mm 4l60e. The input shafts are different on these trannies so I have to use the torque converter that goes with the tranny. I got the tranny to fit up ok by modifying the flexplate holes, but I felt that the Torque converter was too far away from the flexplate after the install. I bolted it up regardless and drove for a little while but my gutt was telling me this would ruin my trans pump eventually.

My questions is, Do I need the flexplate spacer that GM makes? I currently have the flat style flexplate that originally comes on the 5.7L.

Is there a pilot extender that I need? And if I need a spacer or pilot extender, what will this do to the seating of my starter?

Do I need an after market flaxplate?

Please HELP! I need my harbor truck running ASAP!

 

[CaptainChad]

Just want to update you donkeys on my progress since ive gotten no feedback.

So far I've elongated the flexplate mounting holes, about 1/4" difference from the LT tranny and the LS tranny.

I bought solid 1/4" spacers to fill the gap between the LT (flat) flexplate to the LS tranny torque converter.

LS Tranny fits up nicely with its original bellhousing to my 5.7L LT.

I did have to buy longer torque converter bolts to make up that 1/4" difference between the flexplate and TC.

I plan on putting on the rest of the stuff soon and will update.

 

[jaeross57]

I've been going at this project for a long time. Ive dropped and bolted up the tranny about 4 times, trying to figure this out. Im trying to put a 2002 4l60e (LS) 300mm tranny into a 98 Tahoe that had the (LT) 298mm 4l60e. The input shafts are different on these trannies so I have to use the torque converter that goes with the tranny. I got the tranny to fit up ok by modifying the flexplate holes, but I felt that the Torque converter was too far away from the flexplate after the install. I bolted it up regardless and drove for a little while but my gutt was telling me this would ruin my trans pump eventually.

My questions is, Do I need the flexplate spacer that GM makes? I currently have the flat style flexplate that originally comes on the 5.7L.

Is there a pilot extender that I need? And if I need a spacer or pilot extender, what will this do to the seating of my starter?

Do I need an after market flaxplate?

Please HELP! I need my harbor truck running ASAP!

What engine is in the 99?

 

[jaeross57]

What engine is in the 99?

I'm pretty sure that the 4l60 transmission except some older transmissions have a 2 piece bellhousing.

 

[CaptainChad]

What engine is in the 99?

It’s the 5.7l 99 Tahoe. Transmission came from a 01 Tahoe with a 5.3

 

[CaptainChad]

I'm pretty sure that the 4l60 transmission except some older transmissions have a 2 piece bellhousing.

the 4l60e from the 01 tahoe is a 300mm with a single piece bell housing, biggest difference in the housing is that theres a top mounting bolt hole on the housing. As for the 98 4l60e, its a 298mm and doesnt have a top mounting hole on the single piece bell housing, nor does it have a drain plug on the transmission oil pan.

 

[jaeross57]

the 4l60e from the 01 tahoe is a 300mm with a single piece bell housing, biggest difference in the housing is that theres a top mounting bolt hole on the housing. As for the 98 4l60e, its a 298mm and doesnt have a top mounting hole on the single piece bell housing, nor does it have a drain plug on the transmission oil pan.

I'm glad you were able to figure out what was going on and I got to learn something new. Well actually old.

 

[CaptainChad]

Update:

I got everything in. She runs and drives and shifts. Shimming the TQ with 1/4" x 3/8" washers/shims worked great so far. I do have to get a different front drive shaft to fit into the newer gen T-case. The old T-case has a male end for front drive shaft, the newer one has female end, 32 teeth. I do still need to do a crankshaft position relearn and I should be good to go. fingers crossed. I hope this helps whoever out there.