I am at the point where I want to start on the gearing on my 68. I need to do this in steps. I can't just drop $6000 all at once. I have a powerglide that has to go for obvious reasons and want to go 700R4. I currently have a 10 bolt with I think a 2:70 or something close. Can I do the 700R4 first and run the old 10 Bolt or would it be better to do the 3:73 12 bolt first?
mferris72
You can do the transmission first and use it as a 3 speed until you get the gears changed. That's what I did in a '80 ElCamino that I had. It had 2.73 gears and I couldn't use overdrive until I put in 3.42 gears.
I'd definitely do the trans first, just make sure you either go with a lockup converter or be careful about running 4th gear too much without a lockup converter -- too much driving around with the converter slipping tends to heat the tranny fluid up real fast, which isn't a good thing for overall longevity. Even with a 2.73 rear, the 700R4 will make a bug difference in how the car drives and it'll be a LOT less annoying than a powerglide w/ 3.73's.
I would do a tranny first. MAKE SURE its a beast sunshell. They are the weakest part of the transmission.
I am assuming its an 8.2. If it is I would change it eventually if its an 8.5 i would swap new gears in it and call it good.
Also keep in mind the 700r4 needs a detent cable which controls line pressure. THIS CANNOT be screwed up or the transmission won't last more than 1000 miles.
If you are going to spend 6 grand you better be going with the 4L60E. I can get a 4L65E out of a junk yard relatively cheap pick up a GMPP controller for about a grand. Have the 65E rebuilt and buy a new TC for about 3500 if not less. TC maybe a 800 if a top of the line convertor, tranny 1000+ in good condition maybe 600 needing a rebuild and spend 800-1000 on rebuild. Then 1000 or so on the controller. You got lock up do not have to worry about the detent, have full control of shift points and line pressures.
12 bolt shouldn't be more than 2-2500. I know a guy who builds 9 bolts for right at a grand in St. Louis. Thats what im doing personally. 12 bolts are alot more for a couple percent parasitic loss savings.
I am assuming its an 8.2. If it is I would change it eventually if its an 8.5 i would swap new gears in it and call it good.
Also keep in mind the 700r4 needs a detent cable which controls line pressure. THIS CANNOT be screwed up or the transmission won't last more than 1000 miles.
If you are going to spend 6 grand you better be going with the 4L60E. I can get a 4L65E out of a junk yard relatively cheap pick up a GMPP controller for about a grand. Have the 65E rebuilt and buy a new TC for about 3500 if not less. TC maybe a 800 if a top of the line convertor, tranny 1000+ in good condition maybe 600 needing a rebuild and spend 800-1000 on rebuild. Then 1000 or so on the controller. You got lock up do not have to worry about the detent, have full control of shift points and line pressures.
12 bolt shouldn't be more than 2-2500. I know a guy who builds 9 bolts for right at a grand in St. Louis. Thats what im doing personally. 12 bolts are alot more for a couple percent parasitic loss savings.
I have done both. But I did just the opposite as the others have suggested. I swapped my 8.2 for the 12 bolt first. Then the following year rebuilt a 700R4 and installed it. The swapping out of the rearend I feel was easier to do with less down time. But that isn't so much an issue if these are winter projects. I also started out with a TH350 not a PG. So maybe in your case tranny first, rearend second. When you do the tranny IMO to make it easier, use the Shiftworks kits and the TV cable set up from BTO.
I had a 700R4 built with a kit from Mr. Transmission (I think that's right) that locked up the torque converter without any external wires. I had to modify the cross member and get a shorter dirve shaft. This was for my '81 El Camino. It already had the brackets for the cable, so that wasn't a problem.
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