What T-case crossmember for 465/420& 3spd case

[Domek]

I want to do the change from the 4spd combo(stock) to 465or 420 and 3spd t-case.

What t-case crossmember is being use with these combos, if any?

My 40 runs a strong V8 with a weak 4spd case& AA Crossmember(know as propeller style) which it sucks. I have taken it to different tranny shops to solve the problem and the mechanics said that the engine has too much power and it loosens up the studs on the T-case crossmember. I had run 33's, and now 37's. The weight of tires I don't believe would be related to it at all. Even w/ 33's the case would loosen up the studs and will cause the oil leak.

I want to do the 465 or 420 w/ 3spd.

what are you guys using to carry the case?

can I run it w/out a crossmember?

Please advice!

Show what you are using. Some pictures will help even better.

Ever since the the V8 conversion was made the problem has been there. loose studs= oil leaks=Wife upset.

Thanks!

 

[Sputnik40]

I can't fully answer your question, but can relate and maybe give some input. I've been running a stock 6 with an SM420 and AA adaptor to a self built 74 transition case. I was running 2 motor mounts, stock 4 speed bellhousing mounts to the 3 speed bellhousing, and the rear krappy prop style crossmember. The AA adaptor is 4.5 inches long and I was always nervous having that much weight/torque hanging unsupported so I added the AA prop. It has always leaked like a sieve!

I'm currently building a mega beefy skid plate using 1.5" x .125 wall square tubing (will also serve as my traction bar shackle mount) and removed the rear AA cross member and plan to use the tranny mount that is integrated into the 4.5" AA SM420 adaptor. This will continue to give me that little bit of extra support on the rear floating tranny/t-case. The 4.5" adaptor tranny mount is just a flat spot between the transmission and t-case with 2 bolt mounting holes. To install a cross member here you have to go under the front output of the t-case - it's a bit of a bend for tubing - but was pretty easy for the square tubing I cut and welded up.

I'd suggest using this for your SM420 or SM465 conversion but have heard that the 4.5" AA adaptor might not be strong enough when used with just 2 V8 engine mounts. I'd call AA direct and get their input. They also list a cross member for this adaptor on their webpage - but the PN doesn't have a pic and I couldn't find anything more than the reference to it - again maybe give AA a call?

Since removing that rear cross member - my leaks have all but disappeared. And yes - even thought it was just extra support, the frame flex caused the bolts to wallow out or loosen frequently.

Best of luck - I'll be watching for better responses/solutions.

Bill.

 

[LC_Hamma]

I can surely relate to the propellor style tcase mount causing leakage with the AA adaptor. Although, I didn't have a support under the adaptor itself. I just started bending up a skid for my 55 & this time I'll still use the prop. mount & have just bought the $27.00 bushing/ mount for the adaptor today. They said it's a common GM mount - part #716003
http://72.20.96.178/commerce/ccp1483-crossmember-mount-716003-716003.htm

 

[Sputnik40]

Great info. - I was going to make my own mount to my new cross member - but would prefer to buy one if it works (fits my low profile crossmember dimensions) - I can't open the link - but will try and look up the PN - can anyone else open the link - I'd like to see the part.

I can surely relate to the propellor style tcase mount causing leakage with the AA adaptor. Although, I didn't have a support under the adaptor itself. I just started bending up a skid for my 55 & this time I'll still use the prop. mount & have just bought the $27.00 bushing/ mount for the adaptor today. You can see it on part #716004 2nd page, right in the middle:
http://advanceadapters.dirxion.com/Main.asp

 

[pb4ugo]

I've run a V8 and the AA propeller crossmembers for 10+ yr or more. Never really had issues w/ leaking , but I have gone thru a number of broken cases. When talking to AA and other people, I came to the conclusion that the crossmember to frame bolts should not be too tight. Loose bolts w/locknuts allows the motor/drivetrain assembly and frame to flex independently w/o putting stress on the T/C. Remember, in the stk configuration the trans & T/C case has no support. Just a Thought.

 

[Domek]

Well the Crossmember in that link looks like it's the one for the auto tranny. is that what we are talking about here?

 

[Domek]

I also saw in a different threat that someone cut the Tranny shaft cover on the AA propeller crossmember. They cut what I called small cup.

They cut it and made a hole and put the stock cover and then the bolts.

Picture this the T-case+crossmember+stock cover and what appears to be the stock bolts.

Does that work? I don't know.

I would like to see pictures if someone might have any.

Thanks

 

[LC_Hamma]

<Loose bolts w/locknuts allows the motor/drivetrain assembly and frame to flex independently w/o putting stress on the T/C.>

Hmm, I have the prop mounts on both of my LC's now mounted firmly, so I guess I need to take out the rubber bushings & let the tcase float w/ loose bolts

 

[LC_Hamma]

I also saw in a different threat that someone cut the Tranny shaft cover on the AA propeller crossmember. They cut what I called small cup.

They cut it and made a hole and put the stock cover and then the bolts.

Picture this the T-case+crossmember+stock cover and what appears to be the stock bolts.

Does that work? I don't know.

I would like to see pictures if someone might have any.

Thanks

I've had to cut the cone off the back of the prop mount, but only to run the Pardi Plate stiffener on both my 40 & 55, where I'm running SM420's. Stock covers are req'd. over the plate stiffener. I have pics on page 7 of my 55 buildup.

 

[Domek]

Well I just happen to have a 3spd with that Pardi plate that you're talking about and t-case saver.
So let me see I understand here.

it will be the gasket + propeller crossmember+ Pardi plate Stock cover then bolts.
Also loosen up the bolts on the propeller mounts to have a little room for the propeller crossmember to till whenever there's a small movement from the t-case in order to eliminate loosen up or breaking in this case the T-case.

Did I get it right?

 

[LC_Hamma]

Well I just happen to have a 3spd with that Pardi plate that you're talking about and t-case saver.
So let me see I understand here.

it will be the gasket + propeller crossmember+ Pardi plate Stock cover then bolts.
Also loosen up the bolts on the propeller mounts to have a little room for the propeller crossmember to till whenever there's a small movement from the t-case in order to eliminate loosen up or breaking in this case the T-case.

Did I get it right?

You should have an alum 1/8" disk that goes on first, then the prop mount, plate stiffener, then stock cover last. You should also have the studs installed that come with the kit I assume, don't use the stock bolts there ;p

 

[pb4ugo]

<Loose bolts w/locknuts allows the motor/drivetrain assembly and frame to flex independently w/o putting stress on the T/C.>

Hmm, I have the prop mounts on both of my LC's now mounted firmly, so I guess I need to take out the rubber bushings & let the tcase float w/ loose bolts

No, install the bushings too. I use to snug the bolts down then back them off a little.

I considered the 3speed case too, I like the lower gears but felt its strength was an issue. I couldn't justify the dollars for the conversion and the lack of available 3 speed cases, if there was a problem. So, I went a different route.

 

[Domek]

LC I have not checked yet for that 1/8 aluminum disk. Would this alum disk replace the gasket? you never mentioned a gasket.

LC so the studs would be a stronger choice then the stok bolts?





PB4ugo I am planning on using the bushing on prop mounts. It didn't make sense w/out bushing because there will be a lot a noise.

 

[pb4ugo]

I also saw in a different threat that someone cut the Tranny shaft cover on the AA propeller crossmember. They cut what I called small cup.

They cut it and made a hole and put the stock cover and then the bolts.

Picture this the T-case+crossmember+stock cover and what appears to be the stock bolts.

Does that work? I don't know.

I would like to see pictures if someone might have any.

Thanks

When I converted to a V8 back in the 80's, the propeller crossmember did not have a cone on it. It just had a hole for the shaft to go thru and you used the stk cone and they supplied new longer bolts. It never leaked.

 

[Domek]

PB4ugo

For some reason I believe that the bolts will be a better choice then the studs.

I don't know if it's because at this time that's what I have and the leak but I will consider both options.