Pilot bushing for 4 speed swap

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evans68cuda

evans68cuda

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so just bought myself a 68 barracuda with a 318 904 and 8 3/4 last week. I wanted to do a 4 speed swap and came across a barracuda with a 340 and 833 for sale near me. It was in really bad shape so I called the guy and asked if he'd sell me the trans and all the linkage. Surprisingly he said yes so I got the trans, shift linkage, clutch linkage, bell housing, pedal assembly, column, and driveshaft. Now here's where I'm confused, since my car was originally an automatic, will there be a problem? I have heard that I either need to cut off an inch off the tip of the input shaft, I've heard that the trans will need to be completely disassembled and the input shaft will need to be taken out and machined down to fit in the crank, I've also heard that I will need to pull the crank out and get it machined to accept the input shaft. I have been doing research non stop for like 5 days and keep finding deifferent answers and Brewers was no help at all. Anyone with experience who could give me advice would be a big help. Thanks!
 
Use a later Magnum pilot bearing FC69907. Tap the bearing into the end of the crank. You should not have to shorten the input shaft but mockup or measure to be sure.
 
When I was first checking into this swap, I first thought there wasn't any pilot bearing hole in the crank for automatics. I was told that wasn't correct, you just needed a special bearing to install. Please correct me if I am wrong... Thanks
 
You have options, and none of those options require you to disassemble anything! First, simply check the rear register of the crank for the pilot bushing, you may get lucky and there will be one already installed! If there is not one, you can have the outside diameter of a new bushing turned down to the pilot hole size by any competent machine shop, and just tap it into the unreamed hole, which is what I've done more than a few times with no problems! You can also buy the pilot bearing that fits into the crank register where the snout of your automatics torque converter about would usually ride!! Then just assemble as usual and you will be all set! You're gonna need the pedals too, as I'm sure you know, and I hope you grabbed the frame mounting bracket for the Z bar!
 
Good stuff, I was looking at installing a Tremec 5 speed in mine, the wife put that one away, too much money....
 
So sounds like all I need is that conversion bearing from Brewers? Unless the depth isn't enough in the crank? What's the minimum for how deep it is?
 
If you are lucky there will be pilot bearing in the rear of your crank already. Not likely.

The hole in the crank is probably there and may already be reamed for a standard bronze pilot bushing. Available at most any parts stores.

If not reamed, you can use the later Magnum bearing already mentioned. Also available at parts stores like NAPA. But you will have to shorten the input shaft by something like 3/8 to 1/2". You can take measurenents and calculate it. No need to disassemble the trans. If it was me I'd use a pneumatic cut-off tool (3"-4" dia) and chamfer the shaft with a file.
 
Did you grab the flywheel and all that, too? That gets expensive fast. Your engine should be neutral balanced as should the 340. (except late 340s with cast cranks). Which ever way you go, whichever pilot bushing/input shaft combo you end up with, test fit it without a clutchplate or pressure plate. Make sure your input shaft doesn't bind or you will forever be chasing problems.
 
Revhendo said:
Did you grab the flywheel and all that, too? That gets expensive fast. Your engine should be neutral balanced as should the 340. (except late 340s with cast cranks). Which ever way you go, whichever pilot bushing/input shaft combo you end up with, test fit it without a clutchplate or pressure plate. Make sure your input shaft doesn't bind or you will forever be chasing problems.
Click to expand...
Yes I have the flywheel which I'm going to get resurfaced soon. What should I check for when test fitting? As long as it slides in am I good?
 
KosmicKuda said:
If you are lucky there will be pilot bearing in the rear of your crank already. Not likely.

The hole in the crank is probably there and may already be reamed for a standard bronze pilot bushing. Available at most any parts stores.

If not reamed, you can use the later Magnum bearing already mentioned. Also available at parts stores like NAPA. But you will have to shorten the input shaft by something like 3/8 to 1/2". You can take measurenents and calculate it. No need to disassemble the trans. If it was me I'd use a pneumatic cut-off tool (3"-4" dia) and chamfer the shaft with a file.
Click to expand...
I did a 4 spd conversion to my 69 Barracuda also. It was an original automatic car. The crank already had a pilot bearing in it. I've been told it is not that uncommon. So my advice is to look before you leap.
 
68cuder said:
Yes I have the flywheel which I'm going to get resurfaced soon. What should I check for when test fitting? As long as it slides in am I good?
Click to expand...

Not just slides in, make sure it spins freely. It might even be worth the time to make sure the center bore on the bell is lined up with the crankshaft. I've done conversions where the input slid in, but it bound up, sometimes to the pilot bushing not having the proper i.d., or some cases where the bell wasn't aligned. It will make a difference on how your trans shifts.
 
So finally got the motor out. So will my a833 work with this?

image.jpeg


image.jpeg
 
I believe you just need the adapter bearing from Brewers. I believe the small blocks are drilled deep enough to not have to cut off the input shaft. Mine is on my 360 anyway.
 
KosmicKuda said:
If you are lucky there will be pilot bearing in the rear of your crank already. Not likely.

The hole in the crank is probably there and may already be reamed for a standard bronze pilot bushing. Available at most any parts stores.

If not reamed, you can use the later Magnum bearing already mentioned. Also available at parts stores like NAPA. But you will have to shorten the input shaft by something like 3/8 to 1/2". You can take measurenents and calculate it. No need to disassemble the trans. If it was me I'd use a pneumatic cut-off tool (3"-4" dia) and chamfer the shaft with a file.
Click to expand...
My 360 crank was drilled deep enough I didn't have to cut off the input shaft... just use the adapter bearing.
 
Make sure it hasn't been chopped off already. Seems pretty common these days.

I would figure depths as such.......
.650" for the converter or bearing depth
plus
1.000" for bushing depth
plus
.500" for the input shaft nose tip
So about 2.150" total.

Some rough numbers I came up with from a 440 crank some time ago. The diameters aren't exact but the depths were measured with a depth mic..........
CrankDepthDiam.jpg


IMO, if you use the bearing instead of the bushing you may want to consider indicating that bell housing in as close as possible.
 
I'm sorry I'm kinda lost. So what length should the input shaft be if it's uncut? Can I just mock the trans up to the motor and see if it fits?
 
68cuder said:
I'm sorry I'm kinda lost. So what length should the input shaft be if it's uncut? Can I just mock the trans up to the motor and see if it fits?
Click to expand...
FWIW........
First, I can take no responsibility should you cut your input shaft too short. It is solely up to you to where you cut it should you choose to do so.
So let's go at it a little differently.
I will afford this example of measurements I have taken.
On a 4 speed I have, the UNCUT input shaft checks 8.625" from the case face.
A Mopar bellhousing is 7.380" per the Mopar Performance Chassis Manual.
8.625" - 7.380" = 1.245"
So the input shaft extends past the bell housing 1.245" when the bell and trans is assembled.
The crank flange of a 440 I have extends .875" from the rear block face.
1.245 + .875" = 2.120"
So 2.120" would be the minimum depth the bore in the crank needs to be for THIS trans.
You will need some extra depth for which ever route you decide as to not bottom the input shaft on the crank bore.
Does this make sense to you?

Your image with color representation..........
flgimage.jpeg.jpg
 
Mock it up with the bellhousing, you don't need a clutch set up for that. Hands on that way. Take some measurements. IMO you will be ok. By the way, a good time to dial in your bellhousing (center it) Not to confuse things but this is a good idea. You may want to Google it.
 
W
marksmopar1 said:
Mock it up with the bellhousing, you don't need a clutch set up for that. Hands on that way. Take some measurements. IMO you will be ok. By the way, a good time to dial in your bellhousing (center it) Not to confuse things but this is a good idea. You may want to Google it.
Click to expand...
what do you mean by center my bellhousing? The holes should automatically line it up I thought
 
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