Welcome. You've headed down a long road... I see it was an original manual trans car. If you remove the frame tab for the Z bar, don't throw it away. I'll take it !! My '66 was originally Butternut Yellow too. It's orange now and will be Aztec Bronze "someday".
Your roto looks good but it looks like you are using pinch bolts to hold the center section in place. If you plan to cut much of the floor or rockers out, I suggest drilling holes all the way thru to prevent the bolts from slipping. I learned that the hard way on my '67 GTO. The pinch bolts WILL slide, unless you crank them into the bar so far, they won't come out. I like the extra wheels under the center to prevent sagging...
The body seems to be in good conditon. What is it like under the primer and what are your plans for the car...resto-mod, pro-street, stock sleeper ??
What part of town are you in ? Never know when one of us will wander by and stop in to see it.
Are you talking about the center one or the ones that actually attach to the car. The center one also has an acme thread for fine adjustment so it wont move.
-- Edited by MACK5555 on Wednesday 19th of September 2012 10:33:00 PM
67ss said
Sep 19, 2012
Welcome to the group. I'm jealous hope to be doing that with my 66 in a couple years.
MACK5555 said
Sep 19, 2012
Right now we have a:
1966 327 Small Block
10 Bolt 8.2" 3.31 Rear End Non-Posi
Power glide and some other trans laying around
Looking to use:
1966 327 Small Block
12 Bolt 3.31 Rear End W/Posi
700-R4 Tranmission
Any suggestions on trans or rear end gearing? We figured this would give nice low end torque plus still a good highway RPM.
yellowbowtie said
Sep 20, 2012
Looks good, keep the pics coming
67ss said
Sep 20, 2012
MACK5555 wrote:
Right now we have a:
1966 327 Small Block
10 Bolt 8.2" 3.31 Rear End Non-Posi
Power glide and some other trans laying around
Looking to use:
1966 327 Small Block
12 Bolt 3.31 Rear End W/Posi
700-R4 Tranmission
Any suggestions on trans or rear end gearing? We figured this would give nice low end torque plus still a good highway RPM.
That should be a good combination. You can google some rpm calculators to figure out engine rpm at different speeds to verify where you want to be.
I am hoping to get the 4 speed and disc brakes into mine this winter. I plan on a 327 eventually but will run the 283 for now.
SShink said
Sep 20, 2012
Josh, welcome to the forum and NCC! Looking forward to meeting you if you make one of the monthly meetings.
Great start going from raw tubing to having it on the rotiserie!
I'm sure a few of our '66 owners will be watching your progress with an envious eye.
Chris R said
Sep 20, 2012
SShink wrote:
Josh, welcome to the forum and NCC! Looking forward to meeting you if you make one of the monthly meetings.
Great start going from raw tubing to having it on the rotiserie!
I'm sure a few of our '66 owners will be watching your progress with an envious eye.
More 66 owners is just fine with me. So ill be watching. For starters, it has the correct number of headlights. Which is always good.
Lost in the 60s said
Sep 20, 2012
Welcome. You've headed down a long road... I see it was an original manual trans car. If you remove the frame tab for the Z bar, don't throw it away. I'll take it !! My '66 was originally Butternut Yellow too. It's orange now and will be Aztec Bronze "someday".
Your roto looks good but it looks like you are using pinch bolts to hold the center section in place. If you plan to cut much of the floor or rockers out, I suggest drilling holes all the way thru to prevent the bolts from slipping. I learned that the hard way on my '67 GTO. The pinch bolts WILL slide, unless you crank them into the bar so far, they won't come out. I like the extra wheels under the center to prevent sagging...
The body seems to be in good conditon. What is it like under the primer and what are your plans for the car...resto-mod, pro-street, stock sleeper ??
What part of town are you in ? Never know when one of us will wander by and stop in to see it.
Lost in the 60s said
Sep 20, 2012
The bar under the car that adjusts length and attaches the two ends. If you don't plan any major floor or rocker work, the extra casters you have near the center should be enough to prevent sag.
After I cut out most of the floor and rockers on mine, it sagged and that bar slipped on the pinch bolts. I had to use a come along to pull it back together. You can see it in this pic.
MACK5555 said
Sep 20, 2012
Oh ok I see what you mean now, and yes we will be doing major floor and rocker work. I will definitely look into this as it would be an easy fix.
MACK5555 said
Sep 21, 2012
Has anyone here put a 700R4 in a 66? We need to do the floor and I am wondering if there is any massaging that needs to happen?
Some forums say there is and others say they no issues.
-- Edited by MACK5555 on Friday 21st of September 2012 09:28:04 AM
67ss said
Sep 21, 2012
Have only done it on a 72 and it cleared the floor fine. My buddy fit a 4l80 in his 66 which is bigger then a 700 with some minor hammering so I don't think you will have any problems.
Check your PM's I sent a question to you.
bowtie said
Sep 21, 2012
IIRC, the 700R4 and TH350 are similar dimensionally that way. Also, the truck ones have a mounting pad in a different spot since there's no tailshaft cone. If you get a truck one, you add a tailshaft cone and then end up with 2 mounting spots.
Chris R said
Sep 21, 2012
MACK5555 wrote:
Has anyone here put a 700R4 in a 66? We need to do the floor and I am wondering if there is any massaging that needs to happen?
Some forums say there is and others say they no issues.
-- Edited by MACK5555 on Friday 21st of September 2012 09:28:04 AM
Are you planning to reuse the tunnel thats there or replace that when your doing the floors too?
Bungy L-76 said
Sep 22, 2012
I put a 700R4 in my 64, which has the exact same floor pans as your 66, and I had to hammer on the tunnel slightly to clear the round servo that sticks out the passenger side. This kept the trans from sitting straight. Wasn't much, in fact you couldn't even see the "dimple" on the inside with carpet installed. The rear crossmember simply slid back an inch or two and I drilled new mounting holes on the frame brackets. Mine is a convert so your crossmember attachment might be different.
I have since removed the auto and installed a Muncie. My Chevelle isn't a "long hauler" so I'm not too concerned with the RPMs. The manual is a LOT more fun. My old Bel-Air that I take on vacations and drive cross country will be getting a 200-4R soon though.
Bungy L-76 said
Sep 22, 2012
Just wanted to add that I think your choice of a 3.31 rear and the 700R4 is a perfect combination with the 327.
MACK5555 said
Sep 22, 2012
Thanks for the info guys. We are trying to get our drive-train figured out so we can have a plan. I think we are pretty set on the 327, 700r4, 3.31-3.38 rear end. Right now the only thing we looking for is what tires fit in the stock tubs, we are keeping the car at the stock height. Is there a website that will give us sizes that will fit, mainly worried about the height of the tire at the moment as different rims can move the tire in an out, but width obviously does matter.
66 RAT said
Sep 24, 2012
I'm also a '66 owner and will be looking forward to following the progress that you and your dad make on this project. It will help make the winter months go a little faster. Will it be primarily just you and your dad doing the work on the car?
67ss said
Sep 24, 2012
MACK5555 wrote:
Thanks for the info guys. We are trying to get our drive-train figured out so we can have a plan. I think we are pretty set on the 327, 700r4, 3.31-3.38 rear end. Right now the only thing we looking for is what tires fit in the stock tubs, we are keeping the car at the stock height. Is there a website that will give us sizes that will fit, mainly worried about the height of the tire at the moment as different rims can move the tire in an out, but width obviously does matter.
I am pretty sure mitch is running a 275 60 15 on his 66, I am running a 255 70 15 on mine. Both of us have 7 inch wide rims.
Lost in the 60s said
Sep 24, 2012
Yes, I have 275 60 15 on '71-72 stock 15X7 SS wheels with NO rub issues... tires are 28" tall. They do bulge slightly in the center and would benefit from an 8" wheel.
MACK5555 said
Sep 25, 2012
66 RAT wrote:
I'm also a '66 owner and will be looking forward to following the progress that you and your dad make on this project. It will help make the winter months go a little faster. Will it be primarily just you and your dad doing the work on the car?
Yep mainly just me and my father. Winter will help unfortunetly things are going to be delayed a little bit as he just had to spend a ton on a new HVAC system, but we will still be pecking away at it.
John D said
Sep 25, 2012
(Mod - moved pertinant contents to this thread)
67ss said
Sep 25, 2012
This is a good web site for rear differential information. Incase you go looks at some other rear ends. Has good pictures and lots of part numbers. You might contact him he buys and sells used parts.
There's a swap meet this Sunday at the State Fairgrounds. There may be a 12 bolt there. If the weather is decent, I will be out there scrounging.
MACK5555 said
Oct 15, 2012
BBB.org is trying to handle my other issue, as far as the car its on hold at the moment. My wife's vehicle just had the transmission go out so we are tearing in to that at the moment, also my father just put a new HVAC system in his house (heater and AC) so money for the car is none existent at the moment. Definitely keep your eyes open for a 12 bolt, since the issue we had with the first rear end we were possibly thinking about sticking to a 10-bolt since we are only going to be running 350-400hp max but that has not been decided yet.
Transmission in the wife's car is a 4L60E which from what I have read is similar to the 700R4 so should be good practice!!
Lost in the 60s said
Oct 15, 2012
MACK5555 wrote:
BBB.org is trying to handle my other issue, as far as the car its on hold at the moment. My wife's vehicle just had the transmission go out so we are tearing in to that at the moment, also my father just put a new HVAC system in his house (heater and AC) so money for the car is none existent at the moment. Definitely keep your eyes open for a 12 bolt, since the issue we had with the first rear end we were possibly thinking about sticking to a 10-bolt since we are only going to be running 350-400hp max but that has not been decided yet.
Transmission in the wife's car is a 4L60E which from what I have read is similar to the 700R4 so should be good practice!!
For your hp goal, an 8.5 10 bolt is perfectly good. The current 12 bolt you bought would be fine for that level too. Maybe see if there is a power trax or locker available for it that goes in the carrier.
I hear ya on the HVAC. We had to replace all of ours 6 years ago and it was 10k...
MACK5555 said
Oct 15, 2012
Right now the 10-bolt we have is a 8.2" but that might just have to work for now.
Lost in the 60s said
Oct 15, 2012
MACK5555 wrote:
Right now the 10-bolt we have is a 8.2" but that might just have to work for now.
If you don't hammer on it mercilessly, it will hold up until you find the axle you want.
Derek69SS said
Oct 15, 2012
Just put on some BFGoodrich Radial T/As and you won't ever have to worry about breaking anything, except maybe by over-revving from a complete lack of traction.
Lost in the 60s said
Oct 15, 2012
Derek69SS wrote:
Just put on some BFGoodrich Radial T/As and you won't ever have to worry about breaking anything, except maybe by over-revving from a complete lack of traction.
...
John D said
Oct 15, 2012
Transmission in the wife's car is a 4L60E which from what I have read is similar to the 700R4 so should be good practice!!
Yup... Same gearbox except the 4L60e is a electronically/ECM controlled 700R4 (E = electronic).
MACK5555 said
Oct 18, 2012
So finding and getting a good price on 65-66 12 bolt rear ends is tough. In order to save $300-500 is it worth just going to a 68-72 rear end 12 bolt. Main reason I wanted to go with the 65-66 was so everything fit the way it was supposed to and better wheel backspacing. Can you confirm that the only difference is that the total width is longer? Also is there any difference in springs seats and shock mounts and control arms?
Enganeer said
Oct 18, 2012
From what I have gathered, the difference in the rear end width and the spring perches.
1964-67 Chevelle rear end housing measures 53.25 inches from backing plate to backing plate and with the brake drums in place, the total width is 60.00 inches. Axle tube flange-to-flange is 54.25 inches.
* 1968-72 Chevelle rear end housings measure 58.5 inches from flange to flange, and with the brake drums in place, the total width is 62.5 inches. (Note: Other sources put the total width at 61.125" to 61.25".) Axle tube flange-to-flange is 55.25 inches.
* A second measurement to check is centerline distance between spring perch seats. 1964-1967 are 35 1/16 inches between seats where 1968-1972 are 34 31/32 inches.
Another difference is that 1964-66 springs are pigtailed on one end only while 1967-72 rear ends use a cup and is flanged to hold the spring in place
Lost in the 60s said
Oct 18, 2012
I have a '70 12 bolt under my '66 with no issues. As noted, you do need to use the '68-up springs. The other thing you need to do is clearance the stock 10 bolt upper left control arm for the larger 12 bolt housing. I have pics of this I can post or send to you.
As for wheels, unless you are going with something wider than 8", most common wheels fit just fine. I have stock 15X7 71-72 SS Chevelle wheels all the way around on mine.
MACK5555 said
Oct 19, 2012
Picture would be awesome!!
Lost in the 60s said
Oct 19, 2012
Here's the stock arm on a 12 bolt. It is binding and will bend as the axle travels thru the suspension movement.
I used a large washer as a guide and ground off the arm. This allows the arm full travel.
The factory arms have a reinforcement tab spot welded on them, so I welded the washer on too.
Finished modification.
MACK5555 said
Oct 19, 2012
Easy enough, thanks for the pics.
jim larson said
Oct 25, 2012
Mitch, are you sure about the 68 and up springs. I don't want to crawl under the car at the moment; but I think the 66 frame needs 66 springs that have the big circle at the top and the smaller pigtail at the bottom. I thought 67 and up springs had small pig tails on both ends. The 66 spring small end will fit fine over the 67 and up axel assemblys which have the dome tower....
Derek69SS said
Oct 25, 2012
Jim is right. The '66 frame is shaped for a 6" diameter coil at the top. The pigtail on the axle is the same whether it has the early bolt-on retainers, or the later cupped perches.
Later frames can use either style spring. Early frames need early springs.
Lost in the 60s said
Oct 25, 2012
jim larson wrote:
Mitch, are you sure about the 68 and up springs. I don't want to crawl under the car at the moment; but I think the 66 frame needs 66 springs that have the big circle at the top and the smaller pigtail at the bottom. I thought 67 and up springs had small pig tails on both ends. The 66 spring small end will fit fine over the 67 and up axel assemblys which have the dome tower....
Yeah you're right, I have a hybrid frame under mine. It's actually an early '67 style that takes the later spring and has the shovel nose front crossmember. First week of May build.
MACK5555 said
Oct 25, 2012
Yeah I was looking at the frame this weekend and I was confused. It makes more sense now.
MACK5555 said
Nov 10, 2012
Does anyone know what type of steel was used in the frame?
Lost in the 60s said
Nov 11, 2012
Not specicically, but it is just mild steel. Nothing fancy or heat treated. It can be cut with a hack saw and welds easily.
MACK5555 said
Dec 21, 2018
Well after 6 years of not doing thing we are finally getting back to work. New thread soon? Maybe next month with updates.
Lost in the 60s said
Dec 21, 2018
At least you still have the car and will get back to it. Sounds like "someday" just arrived for Christmas !!
Mine has sat for 2 years now, waiting for paint to appear.
jim larson said
Dec 22, 2018
Glad to see your back at the restoration.hopefully we here at NCC can help.
Are you talking about the center one or the ones that actually attach to the car. The center one also has an acme thread for fine adjustment so it wont move.
-- Edited by MACK5555 on Wednesday 19th of September 2012 10:33:00 PM
Welcome to the group. I'm jealous hope to be doing that with my 66 in a couple years.
Right now we have a:
1966 327 Small Block
10 Bolt 8.2" 3.31 Rear End Non-Posi
Power glide and some other trans laying around
Looking to use:
1966 327 Small Block
12 Bolt 3.31 Rear End W/Posi
700-R4 Tranmission
Any suggestions on trans or rear end gearing? We figured this would give nice low end torque plus still a good highway RPM.
Looks good, keep the pics coming

That should be a good combination. You can google some rpm calculators to figure out engine rpm at different speeds to verify where you want to be.
I am hoping to get the 4 speed and disc brakes into mine this winter. I plan on a 327 eventually but will run the 283 for now.
Josh, welcome to the forum and NCC! Looking forward to meeting you if you make one of the monthly meetings.
Great start going from raw tubing to having it on the rotiserie!
I'm sure a few of our '66 owners will be watching your progress with an envious eye.
More 66 owners is just fine with me. So ill be watching. For starters, it has the correct number of headlights. Which is always good.
Welcome. You've headed down a long road... I see it was an original manual trans car. If you remove the frame tab for the Z bar, don't throw it away. I'll take it !! My '66 was originally Butternut Yellow too. It's orange now and will be Aztec Bronze "someday".
Your roto looks good but it looks like you are using pinch bolts to hold the center section in place. If you plan to cut much of the floor or rockers out, I suggest drilling holes all the way thru to prevent the bolts from slipping. I learned that the hard way on my '67 GTO. The pinch bolts WILL slide, unless you crank them into the bar so far, they won't come out. I like the extra wheels under the center to prevent sagging...
The body seems to be in good conditon. What is it like under the primer and what are your plans for the car...resto-mod, pro-street, stock sleeper ??
What part of town are you in ? Never know when one of us will wander by and stop in to see it.
The bar under the car that adjusts length and attaches the two ends. If you don't plan any major floor or rocker work, the extra casters you have near the center should be enough to prevent sag.
After I cut out most of the floor and rockers on mine, it sagged and that bar slipped on the pinch bolts. I had to use a come along to pull it back together. You can see it in this pic.
Has anyone here put a 700R4 in a 66? We need to do the floor and I am wondering if there is any massaging that needs to happen?
Some forums say there is and others say they no issues.
-- Edited by MACK5555 on Friday 21st of September 2012 09:28:04 AM
Have only done it on a 72 and it cleared the floor fine. My buddy fit a 4l80 in his 66 which is bigger then a 700 with some minor hammering so I don't think you will have any problems.
Check your PM's I sent a question to you.
Are you planning to reuse the tunnel thats there or replace that when your doing the floors too?
I put a 700R4 in my 64, which has the exact same floor pans as your 66, and I had to hammer on the tunnel slightly to clear the round servo that sticks out the passenger side. This kept the trans from sitting straight. Wasn't much, in fact you couldn't even see the "dimple" on the inside with carpet installed. The rear crossmember simply slid back an inch or two and I drilled new mounting holes on the frame brackets. Mine is a convert so your crossmember attachment might be different.
I have since removed the auto and installed a Muncie. My Chevelle isn't a "long hauler" so I'm not too concerned with the RPMs. The manual is a LOT more fun. My old Bel-Air that I take on vacations and drive cross country will be getting a 200-4R soon though.
Just wanted to add that I think your choice of a 3.31 rear and the 700R4 is a perfect combination with the 327.
I am pretty sure mitch is running a 275 60 15 on his 66, I am running a 255 70 15 on mine. Both of us have 7 inch wide rims.
Yes, I have 275 60 15 on '71-72 stock 15X7 SS wheels with NO rub issues...
tires are 28" tall. They do bulge slightly in the center and would benefit from an 8" wheel.
Yep mainly just me and my father. Winter will help unfortunetly things are going to be delayed a little bit as he just had to spend a ton on a new HVAC system, but we will still be pecking away at it.
(Mod - moved pertinant contents to this thread)
This is a good web site for rear differential information. Incase you go looks at some other rear ends. Has good pictures and lots of part numbers. You might contact him he buys and sells used parts.
http://www.jdrace.com/
Been a while, any updates?
There's a swap meet this Sunday at the State Fairgrounds. There may be a 12 bolt there. If the weather is decent, I will be out there scrounging.
Transmission in the wife's car is a 4L60E which from what I have read is similar to the 700R4 so should be good practice!!
For your hp goal, an 8.5 10 bolt is perfectly good. The current 12 bolt you bought would be fine for that level too. Maybe see if there is a power trax or locker available for it that goes in the carrier.
I hear ya on the HVAC. We had to replace all of ours 6 years ago and it was 10k...
If you don't hammer on it mercilessly, it will hold up until you find the axle you want.
Just put on some BFGoodrich Radial T/As and you won't ever have to worry about breaking anything, except maybe by over-revving from a complete lack of traction.
Yup... Same gearbox except the 4L60e is a electronically/ECM controlled 700R4 (E = electronic).
From what I have gathered, the difference in the rear end width and the spring perches.
More info click the link.
http://chevellestuff.net/qd/generic_rear_axle_info.htm
1964-67 Chevelle rear end housing measures 53.25 inches from backing plate to backing plate and with the brake drums in place, the total width is 60.00 inches. Axle tube flange-to-flange is 54.25 inches.
* 1968-72 Chevelle rear end housings measure 58.5 inches from flange to flange, and with the brake drums in place, the total width is 62.5 inches. (Note: Other sources put the total width at 61.125" to 61.25".) Axle tube flange-to-flange is 55.25 inches.
* A second measurement to check is centerline distance between spring perch seats. 1964-1967 are 35 1/16 inches between seats where 1968-1972 are 34 31/32 inches.
Another difference is that 1964-66 springs are pigtailed on one end only while 1967-72 rear ends use a cup and is flanged to hold the spring in place
I have a '70 12 bolt under my '66 with no issues. As noted, you do need to use the '68-up springs. The other thing you need to do is clearance the stock 10 bolt upper left control arm for the larger 12 bolt housing. I have pics of this I can post or send to you.
As for wheels, unless you are going with something wider than 8", most common wheels fit just fine. I have stock 15X7 71-72 SS Chevelle wheels all the way around on mine.
Here's the stock arm on a 12 bolt. It is binding and will bend as the axle travels thru the suspension movement.
I used a large washer as a guide and ground off the arm. This allows the arm full travel.
The factory arms have a reinforcement tab spot welded on them, so I welded the washer on too.
Finished modification.
Mitch, are you sure about the 68 and up springs. I don't want to crawl under the car at the moment; but I think the 66 frame needs 66 springs that have the big circle at the top and the smaller pigtail at the bottom. I thought 67 and up springs had small pig tails on both ends. The 66 spring small end will fit fine over the 67 and up axel assemblys which have the dome tower....
Later frames can use either style spring. Early frames need early springs.
Yeah you're right, I have a hybrid frame under mine. It's actually an early '67 style that takes the later spring and has the shovel nose front crossmember. First week of May build.
Not specicically, but it is just mild steel. Nothing fancy or heat treated. It can be cut with a hack saw and welds easily.
At least you still have the car and will get back to it. Sounds like "someday" just arrived for Christmas !!
Mine has sat for 2 years now, waiting for paint to appear.
Glad to see your back at the restoration.hopefully we here at NCC can help.