Midyear rear end swapout

[Jack J.]

I'm curious, what would be average time frame to swap a rear end in a 64 coupe? My original frame has the 3.08 still in it and the new(used)frame came with a 4.11. After body off restoration, I'm considering trying the 4.11 mated with the 365HP but I might want to switch back to the 3.08 later. Any pros or cons? Thanks in advance.

[Mike M.]

Re: Midyear rear end swapout

put 4.11:1 in car and 3.08 on shelf. gas milage will be worse but the acceration thrill will be aewsome.time to switch, if you've done it before, should be couple hours. double it if its your first . mike

[Mike M.]

Re: Midyear rear end swapout

PS---i'm assuming the cr is an occasional use vehicle. if you'll be traversing the country a couple times a year, stiuck with the 3.08. mike

[Jim T.]

Re: Midyear rear end swapout

The 4:11 will sure make driving the streets more enjoyable, no slipping the clutch taking off on a incline from a stop. If your driving is going lots more on the highway or roads above 50mph the 3:08 would keep the on the road RPM's lower and engine wear less. The thrill of stoplight to stoplight accleration will be less though. I had a 64 4 speed convertible with the 3:08, but it had a 327/300 that had more low end torque and I liked the 3:08. Would really wind out in first gear. Drove it coast to coast and halfway back in 1969 and liked the reduced highway RPM level. The gas mileage was good.

[Jack J.]

Re: Midyear rear end swapout

Jim, I remember 1st gear in the 3.08. What a rush from a roll or merging down an on ramp. Seems my average gas milage was around 16 to the gallon. Thought I might want to experience the thrill of the 4.11. Pretty sure I will go with the 4.11 for starters. Thanks

[Joe C.]

Re: Midyear rear end swapout

Jack:

The 365SHP likes the 4.11:1. Not much torque for the 3.08, but it's possible to get it off the dime by slipping the clutch. The 411 setup was much more widely used with the L76 back "in the day".

Joe

[Mike Cobine]

Re: Midyear rear end swapout

Get a friend and plan for an afternoon. A lot depends on how easily things come apart. Also, how easily things go back together.

Three of us changed one in less than 30 minutes once, laying in the grass, along some country airport road in Central Florida about 85 miles south of Orlando. There was incentive.

You have a lot to remove to make it easy, such as exhaust pipes and spare tire carrier.

The best way is to remove the differential and crossmember as a unit and it can be a bear. You remove the two bolts in the underside of the cups, and then pry with the longest prybar you can find (6 ft or more) until the crossmember comes off. For safety, remove the two bolts and insert two bolts about an inch longer so that the crossmember can drop an inch without falling off. Also, place a floor jack under the differential also about an inch below so the diff can drop an inch without falling to the floor.

The 4.11 will be a thrill, however, you will find any interstate travel a real drag, since we are so used to overdrives in cars today and engines idling along at 1500 RPM at highway speeds. Gas mileage will be junk, but you are not driving a '64 for gas mileage.

For overall driving, I have found a 3.55 is a nice compromise of good take-off and still sensible cruising and gas mileage. That is with the wide ratio transmission (2.48, 2.52, etc first).

Don't forget to change the speedometer gear for the 4.11 in the transmission.

http://vettenet.org/sharkrear.html

[Dennis B.]

Re: Midyear rear end swapout

I just went from the 3.08 to a 3.55 in my 66 Coupe with 350/327. Tried to hit the middle and get a little "light to light" fun but still be able to go down the road at 70. This has been an acceptable change for me.

[Michael H.]

Re: Midyear rear end swapout

Joe,

I agree. My "new" 64 365 HP coupe was delivered with a 3.08 and I hated it. Always wanted to switch to a 3.70 or 4.11 but couldn't afford it back then. It did go 86 MPH in 1st gear tho, if I remember correctly, but was miserable to drive, especially with the 2.20 muncie. A 3.70 would be a nice compromise but a 4.11 would still be better than a 3.08, at least for me.

Michael

[Gerard F.]

Re: Midyear rear end swapout

Funny, I did the coast to coast trip in 1969 in a 67 327/300 with a 3.08 rear end. Kept track of mileage and got around 20 mpg. I just checked it a few weeks ago on a long highway trip, got 15.5 mpg. This was 35 years later and plus about 30,000 miles and with a 1976 Holley double pumper. Now I've got something to work on.

Jerry Fuccillo
#42179

[Gerard F.]

But I've had 5 clutches in it with the 3.08

and still geezerlatin' around.

Jerry Fuccillo

[Jack J.]

Re: Midyear rear end swapout

Jerry, I will probably run with my Holley 650cfm double pumper until I can track down the correct Holley for my car. I thought Duke??? ordered his SWC with a 365HP/3.08 combo and not that long ago mentioned his quarter mile time/speed and only using TWO gears!
Jack

[Gary H.]

Re: Midyear rear end swapout

Thanks for the info and the link, as this is something I also need to do with my '64 365Hp. The 4:56 diff is fun, but 45 mph means about 2500+ RPM in 4th gear. I think it's a close ratio M20; basically I don't need 1st and 3rd.
I was thinking I'd go with a 3:70 for all-around driving, unless I hear other recommendations :-)

[Mike Cobine]

Re: Midyear rear end swapout

Back in '76, a friend had a '61 with a 4.88 rear. 45 mph was about it for highway speeds. Lots of jokes about getting out to see if we were moving.

of course, it could go from 0 to 45 in less than you could blink.

Those were the days.

[Michael H.]

Re: Midyear rear end swapout

I bought a new 68 Z-28 that was ordered with a 4.88. Lot of fun but everyone thought I was riding around in 2nd gear. Had a tough time convincing everyone it was stock, factory installed ratio. (that 4.88 was the only way to get those cars to run quick on the street)