How hard/expensive is it to switch out gearing on an A-body?

[svevobandini]

Hey everyone, I've finally found a 4-speed Barracuda in my price range. However, it's a 340 with 3.91 gears. I don't spend much time on the freeway but I do like long drives on smaller roads. I'd like to be able to go 55-60 comfortably. How hard/costly would it be to switch to 3.55 or 3.23?

 

[Treblig]

I would much rather install a 2004R!! I'm running 4:56 gears and my car cruises at 2500 going 65/70 MPH (29" tires)....I love it. When I had 3:90 gears I could cruise at 70MPH doing 2100RPM with a top speed of 180!!!! Why spend money on switching gears when you can keep the gears and increase your gas mileage??

treblig

 

[dukeboy440]

I would much rather install a 2004R!! I'm running 4:56 gears and my car cruises at 2500 going 65/70 MPH (29" tires)....I love it. When I had 3:90 gears I could cruise at 70MPH doing 2100RPM with a top speed of 180!!!! Why spend money on switching gears when you can keep the gears and increase your gas mileage??
View attachment 1715076097
treblig

Why put a Chevy trans in a mopar........ He has a 4 speed 340 car, not exactly found everywhere. And I'm guessing he likes the 833.

Hey everyone, I've finally found a 4-speed Barracuda in my price range. However, it's a 340 with 3.91 gears. I don't spend much time on the freeway but I do like long drives on smaller roads. I'd like to be able to go 55-60 comfortably. How hard/costly would it be to switch to 3.55 or 3.23?

Assuming you have a 8.75 rear, not that bad at all, you can get an assembled center section and swap it in an afternoon fairly quick. plus you could sell the 3.91 center as is and pay for the swap for a 3.23 center section. Youre looking at anywhere from 50 bucks on up to 4-5 hundred bucks for the center sections depending on casting number, sure grip or open and ratio.

 

[Treblig]

Why put a Chevy trans in a mopar........ He has a 4 speed 340 car, not exactly found everywhere. And I'm guessing he likes the 833.

I agree!! A 4 speed car is GREAT!! I put a Chevy trans in my car because it was survivor and didn't want to "cut it up" to install a Mopar trans just to get overdrive.

Assuming you have a 8.75 rear, not that bad at all, you can get an assembled center section and swap it in an afternoon fairly quick. plus you could sell the 3.91 center as is and pay for the swap for a 3.23 center section. Youre looking at anywhere from 50 bucks on up to 4-5 hundred bucks for the center sections depending on casting number, sure grip or open and ratio.

I agree again!! If he can buy everything at the prices you quote it would be great but he'll be limited on gearing for his highway cruising. I get great gas mileage in town as well but "svevobandini" will surely make a decision that best suites his needs.

treblig

 

[dukeboy440]

I agree again!! If he can buy everything at the prices you quote it would be great but he'll be limited on gearing for his highway cruising. I get great gas mileage in town as well but "svevobandini" will surely make a decision that best suites his needs.

treblig

i hear ya, dont get me wrong, I'm doing a TR6060 swap into my dart for that very reason, but when you get into swapping transmissions to modern ones, you start talking about big bucks, mine will run me close to 2500 bucks using a junkyard sourced TR6060. I imagine a 2004R is gonna be at least 1000-1500+ not counting adapter plates and such.

 

[Max1196]

What's your budget? and like previously asked, is it an 8 3/4 type axle?

 

[svevobandini]

Yeah, 8 3/4 rear. I have an extra ~ $1500 I could spend on it right now, but I could also wait and save up more for this if it seems worthwhile. Here is the car in question: 1964 Plymouth Barracuda 340-4speed

 

[Backally]

If it's just a street cruiser, get new 3:23 ring and pinion from Summit for under $300. Pull out the carrier and have it rebuilt with the new gears, prob have $500-600 done

 

[abodyjoe]

Call dr diff and see what he is getting for a 3.23 center section.

 

[brian6pac]

Do you know what 200R4 means ? 200 lbs ft torque 4 speed. I worked for GM for a while and they changed there trans ID a couple times TH350 = 350 lbs ft, TH400 = 400 lbs ft. then they changed it with the 700R4
700 divided by 2 = 350 lbs ft then 4L60E = 4 speed, longitudinal 60 x 10 divided by 2 = 300 lbs ft, E means electronic, 4L80E same but 400 lbs ft of torque. Your way better off with the torqueflite overdrive than a 200R4. A 4L80 is a TH400 with a overdrive gear 4th.

 

[abodyjoe]

I would much rather install a 2004R!! I'm running 4:56 gears and my car cruises at 2500 going 65/70 MPH (29" tires)....I love it. When I had 3:90 gears I could cruise at 70MPH doing 2100RPM with a top speed of 180!!!! Why spend money on switching gears when you can keep the gears and increase your gas mileage??
View attachment 1715076097
treblig

Replace a 4 speed with a 200 auto? Are you freaking nuts? Other them a medical condition you would have to be nuts to do that.

If you want od you can keep the 3:91 gear and just stick a passion od 4 speed in it. Not the 5 speed people are waiting years for but his od 4 speed. There's your best of both worlds and ya don't have to hack the crossmember or ruin the car by putting an automatic in the thing.

 

[273]

Pulling yours and have it rebuilt with the right gears probably the best way to go.

I want the opposite mine came with 2.96 gears and I want 3.91 but want to keep the 2.96 intact for when I do long trips. So I'm looking for a complete 3rd member.
Up here a fully rebuilt 3rd member to be purchased out right is about $1600

 

[rumblefish360]

Mopar 8 3/4" (8.75) 489 Case Third Member

Add a gasket and rtv sealent and a speedometer pinion drive (goes into the trans tailshaft, driverside) to correct the speedometer readings.

From start of project to cleaned up & coffee afterwards, 3 hours taking your time.

 

[69_340_GTS]

Dr. Diff gets around $1400 for an all-new 3.55 geared 489 case with Tru-Trac. That's safest/easiest, but might also be most expensive depending on what other options are available to you.

 

[svevobandini]

Thank you so much everyone. This might be worth making a separate post for, but do any of you have experience with auto to manual swaps? How complicated is it in comparison?

 

[rumblefish360]

To swap from auto To manual you will need;

The pedals from a like car to swap in, the rod that goes from the pedal to the "Z" bar and all the hardware that attaches the "Z" bar to the inner fender and bell housing. There is the fender bolt, washer & nut to hold the Z bar and the plastic parts that go inside the Z bar on both ends, a pair of nut and bolts to hold a metal plate on the transmissions bell housing.
Said bell housing, fork, return spring, adjuster rod, nut and washers.

Possible driveshaft. Shifter boot and trI'm ring to hold shifter boot down. Shifter and rods and shifter handle. Clutch alignment tool
For the pressure plate and clutch disc. Possible Offset dowels To align the bell housing up. Trans mount. (At tail)

BUt before you do anything, the crank must be drilled in order to Accept the transmissions input shaft into the crank with a bearing.

If the crank is not drilled, guess what needs machine work first.

 

[Ottmundr]

Hey everyone, I've finally found a 4-speed Barracuda in my price range. However, it's a 340 with 3.91 gears. I don't spend much time on the freeway but I do like long drives on smaller roads. I'd like to be able to go 55-60 comfortably. How hard/costly would it be to switch to 3.55 or 3.23?

Welcome! I'm just down the road in Santa Rosa.

I'd keep the 3.91 gearing, but the most I usually drive is maybe 40 miles for long trips. I absolutely hate my 2.76 pegleg, but it's staying till I can completely replace my 7 1/4. I like that 6pack hood he has on that car. I agree with getting a second center section for trips, and swapping back and forth as needed for trips vs around town.

 

[69_340_GTS]

To swap from auto To manual you will need;

The pedals from a like car to swap in, the rod that goes from the pedal to the "Z" bar and all the hardware that attaches the "Z" bar to the inner fender and bell housing. There is the fender bolt, washer & nut to hold the Z bar and the plastic parts that go inside the Z bar on both ends, a pair of nut and bolts to hold a metal plate on the transmissions bell housing.
Said bell housing, fork, return spring, adjuster rod, nut and washers...

If I were to do it I'd forget about the clutch linkage, Z-bar, etc... and just get a clutch slave cylinder & hydraulic throw-out bearing. There are kits available. You still need everything else, including the pedals.

 

[svevobandini]

Welcome! I'm just down the road in Santa Rosa.

I'd keep the 3.91 gearing, but the most I usually drive is maybe 40 miles for long trips. I absolutely hate my 2.76 pegleg, but it's staying till I can completely replace my 7 1/4. I like that 6pack hood he has on that car. I agree with getting a second center section for trips, and swapping back and forth as needed for trips vs around town.

Yeah, the more I think about it the more the current setup seems pretty sweet. I like the idea of a second center I could swap in- usually I know when I'll be making a trip and can take some time in advance. Are there any specialized tools I'd need to do this? I have the usual garage stuff- sockets etc. as well as access to a metal shop, but it's geared more towards general machining than auto stuff in particular

 

[barbee6043]

keep the 3:91 and cruise at 55 back roads. great torque multiplication!!!! buy a good used 3:23 sure grip for $400 for back up/

 

[Ottmundr]

By the way, let us know if you get that car, it's pretty sweet and it's not a bad deal since much work has already been done.

I'd ask if he wants to sell that Demon in picture #4 next to it if it's in decent shape. Otherwise I'd make my offer at $5,000. And probably end up at $5,400.

 

[69_340_GTS]

As far as swapping pigs goes, first find out if the rear axles still have OEM adjustable axle (wheel) bearings, or if they have already been replaced by "green" bearings. If you have the OEM adjustable bearings, keep in mind that the pigs must both have the thrust button in the center. And every time you swap pigs you'll be adjusting those axle bearings. If the axles have green axle bearings, then both pigs should not have the thrust buttons.

If you plan on swapping pigs a lot, install a drain plug on the bottom of the axle housing.

And, invest in a transmission jack. Those pigs are heavy!

 

[abodyjoe]

If the axles have green axle bearings, then both pigs should not have the thrust buttons.

If running moser or from what dr diff says his axles the thrust button does not get removed. Have had multiple sets of moser axles with green bearings and never had to remove the thrust button an any center sections.

 

[69_340_GTS]

If running moser or from what dr diff says his axles the thrust button does not get removed. Have had multiple sets of moser axles with green bearings and never had to remove the thrust button an any center sections.

Well, I did say "should not have". I recall having an issue using green bearings, with the thrust button. I was not happy having to remove the pig to remove the button after one of the axles bottomed out before the bearing was all the way into the axle tube. It happened.

 

[Crazy73]

Well, I did say "should not have". I recall having an issue using green bearings, with the thrust button. I was not happy having to remove the pig to remove the button after one of the axles bottomed out before the bearing was all the way into the axle tube. It happened.

Yup, been there - done that.