[2216]

Hello to all once again,I've been working on this swap for a little bit now and have had some questions.The one thing that still has me baffled is the way my flexplate is facing for correct contact with the starter.I pulled the tranny and inspected all things from previous posts I've made.Two questions -if the ring gear side is facing the engine to line up the teeth and starter, my torque convertor does not mount up very easily,like the center of the flexplate has tension against the t/c. Is this the correct way to mount it? Also what about my 72's torque convertor -did I ned to swap the 401's torque convertor to my rig? Man I feel like I've lost all my mechanical ability with this one. More help would be greatly appreciated. Thanks to all! Nate

 

[2216]

Hi to all again -a previous post mentioned that a 77-78range 360 flexpalte is different than a 72-73 range one due to the crank spacer being deleted?If this is true would the same apply from a 78 401 to a 73 401 for the proper depth to get my starter squared away? I believe that if I get a flexplate for a 73 401 all my concerns would go away right? Thanks-Nate

 

[dfjeepster]

Yeah you will need a 72-73 flexplate if you are using a transmission from those years as well as the crank spacer, however I dont think the 401 was available in the Waggys then? A 360 is supposed to be close enough to interchange with them but I dont know if I would do it due to the external balancing although many people say it works??? You could have the flexplate balanced to your 401 though, just make sure it has the correct offset to work with the spacers and adapters.

 

[2216]

Who can balance this flex plate and if so why has no one mentioned using it on this swap before? Can I use the stock 78 Waggy flex plate as is or not? It just goes together so nice one way but the way it needs to be to line up with starter just doesnt seem right. Nate

 

[1078]

Here in town, there is s clutch & u-joint shop that does it, a speed shop that does it, and mass-produced rebuilt engine place that does it. Those are some places to start looking near you. I looked into it for a flywheel to put a buick 350 in my '71 before i learned that the manual 3sp would probably not hold up anyway. But they did auto flex plates, too. The engine rebuilder does mostly mail order, so you may be able to ship yours to them if you can't find anyone locally. I don't know if the have a web site, but they are called ault & james enigines.

 

[dfjeepster]

In reply to:

Who can balance this flex plate and if so why has no one mentioned using it on this swap before? Can I use the stock 78 Waggy flex plate as is or not? It just goes together so nice one way but the way it needs to be to line up with starter just doesnt seem right. Nate

[/ QUOTE ]
Any decent driveline shop or rebuilder should be able to do it, check the yellow pages or look for a speed shop that could recommend someone near you. If you are using the Commando version of the TH400 it will have a bellhousing adapter to mate to the AMC block. Due to this, Jeep used a crank spacer and a specially offset flexplate. The crank spacer goes on the back of the crank to push the flexplate back far enough to allow the torque converter to be bolted to the flexplate and still engage all the way on the tranny. The flexplate for these years is designed so that it has an special offset which spaces the ring gear towards ths starter more to make up for the crank spacer. The later years of Waggys, etc... did not use the bellhousing adapter and therefore did not need the crank spacer so they were able to use a more standard flexplate which does not have the same offset. The later flexplates will bolt up the same but will not engage both the torque converter and starter properly. I just ordered one for a 72 360 from this place and it was half the price of Autozone. It should be here in a few days and I'll let you know if it has the right offset design. Good luck!

 

[dfjeepster]

Heres the list of Jeep flexplates so you can see what years are compatible, etc... flexplates

 

[Caver Dave]

Re: why is this 401 swap giving me so much trouble

Nate,
Do you recall this post?

In reply to:

First, what tranny's in the '72 and what was behind the 401?
Existing manual tranny + 401 (w/ manual tranny) = correct flywheel for the 401
Existing manual tranny + 401 (w/ auto tranny) = correct flywheel for the 401
Existing auto tranny + 401 (w/ manual tranny) = correct TH-400 flexplate for the 401
(you'll already have the adapter for the crank snout & the block-to-bellhousing adapter)
Existing auto tranny + 401 (w/ auto tranny) = correct TH-400 flexplate for the 401
(you'll already have the adapter for the crank snout & the block-to-bellhousing adapter)

Chances are that if the 401 came from an auto, it'll have a TF flexplate. Re-use the crank adapter from the 304 as the TFs didn't use them...

[/ QUOTE ]

I don't remember seeing a reply from you on exactly *what* parts you were trying to assemble, so now may be a good time...before you get frustrated (any more). Sounds like your knocking on the door and want to hear that beast running!

IF you have an AMC 401 and mating it to a (NON-QuadraTrac) TH-400, you'll have to search for the correct flexplate (I believe them to be the same as the flexplates used on the 401/TH400/QTrac waggys).
IF you have the crank spacer (do you?...make dang sure it's there!), the TH400 flexplate WILL fit over the crank spacer nipple (TF flexplate will be too loose)...if you don't, it won't fit on the bare crank (=minus spacer). If you don't have the crank spacer, only a TF (Torque Flite) flexplate will fit on the crank nipple....but no way in #3LL it'll bolt up to a TH400 torque convertor. Also, the TF flexplate will (in most cases) have 4 holes to bolt to a TF torque convertor, but a TH400 flexplate will only have 3.

AFAIK, the TH400 flexplates are ALL the same design, offset, & shape, but are balanced differently between the engines...304, 360, 401.

 

[dfjeepster]

Re: why is this 401 swap giving me so much trouble

Caver, there is a difference in the TH400 flexplates. There are two different styles, 71-73 and 74-79, both designed for AMCs and TH400s but only the early design will work with the TH400 that use the bellhousing adapter. Check out the link I posted a few posts back with the part numbers, years etc.. I have a flexplate from a 71-73 and one from a 78 and when comparing them closely you can see that there is an offset built into it to make up for the crank spacer. I will try to get a picture of them that shows the difference sometime, may be kind of hard to show in a pic though? So Nate if you are using a 71-73 TH400 you will need the crank spacer and a 71-73 flexplate to make it all work. Let us know what years you are trying to mate together and maybe someone here can help out with the right parts.

 

[2216]

Re: why is this 401 swap giving me so much trouble

Alright after much painful discussion I believe I have the solution.I ordered a 72 360 flexplate and have a local machine shop to balance it to my 78 401 flexplate. Double check me but after all of my confussion I think we have it! I 'll keep everybody posted on it and I'm sure something else will arise before this beast is running. Thanks Nate P.S. I learned a long time ago that frustration and jeeps just go together!

 

[dfjeepster]

Re: why is this 401 swap giving me so much trouble

That sounds like it should work out fine, I would double check the flexplate when you get it to make sure they sent you the right one and it will line up with everything correctly before you pay to have it balanced. Good luck and let us know how it turns out!

 

[1967]

Re: why is this 401 swap giving me so much trouble

Here is a good one-------

My 73 commando originally came with the th400 and a 304. Had a 258 and wanted to replace the shot 304.The 258 came from a 78 model with the q-trac as did the flexplate. I used the original th400 with the adapter. Had to build 3 .900 thick spacers to go between the flex and the t/c. Also had to build an extention for the t/c pilot that bolted to the crank.Got this together and it started and ran great. Still use the set-up today. Later on I got to thinking that the starter shouldn`t have worked because it would have been spaced out about an inch too much but it does. From that point on, I decided that mixing and matching jeep parts can be a real PITA.