C4 / adapter gasket

[DJs74]

Hello Guys / Gals,

My gasket between the adapter and C4 is leaking. I haven't purchased the gasket yet and was thinking of making my own from the 0.063" thick gasket material I have on hand. The original gasket is significantly thinner but I realize it has probably been compressed for quite a while so I'm not sure what its original thickness was?

I'm not opposed to buying the specific $5 gasket but rather just a matter of trying to use what i already have available. I have the means to cut the gasket and punch the holes with pretty good accuracy but it probably wont be exact

Is there any reason that I shouldn't / couldn't use the 0.063" gasket material?

Just wondering if the exact outline cut on the inside edge or if the material thickness of the gasket is critical for the transmission to function correctly?

Thanks,

DJs74

 

[Viperwolf1]

The original gasket is probably close to .015" but there is no reason why a thicker one wouldn't work.

 

[blubuckaroo]

That gasket isn't unique to a Bronco. You should be able to get it from a good (good) part store. It's just a C4 tail shaft housing gasket. Try Napa.

 

[DJs74]

Thanks guys!

DJs74

 

[diggs00]

I have a leak here as well, what is the process in replacing this gasket?

 

[thegreatjustino]

I've mated them using nothing but a bead of silicone. The gasket thickness won't make a difference.

 

[dholder]

Use the round end of a ball pein hammer to tap the gasket paper. The sharp edges of the housing will cut a perfect gasket, even the bolt holes.

 

[diggs00]

How do you get to this gasket, mine is leaking as well. Do you have to drop the whole transmission?

 

[DirtDonk]

You do have to separate things of course, but pretty sure it can be done in the vehicle. Dropping the transfer case and adapter out first, with maybe letting the rear drop a bit to better clear the body. This requires removing the crossmember, but you're likely better getting it out of the way anyway, no matter what you try.

But that's all just hearsay, as I've never done an auto in the truck myself. These guys will pop back in I'm sure to give any further gory details. But yes, as you're imagining, it's a bit of a hassle.

How bad is it leaking? If it's just a drip, maybe you can get lucky and run a bead of sealant around the seam with your finger? And also check to make sure that all bolts are tight in case something is just coming loose.
If it's a full-on drip that leaves a mess on the garage floor though, it's probably time to pull it apart and put the new one in.
It's not a very substantial gasket as you can see here: http://www.wildhorses4x4.com/product/C4_to_Adapter_Gasket but it still takes just as much work to replace it as anything else in the drivetrain.

Good luck.

Paul

 

[diggs00]

You do have to separate things of course, but pretty sure it can be done in the vehicle. Dropping the transfer case and adapter out first, with maybe letting the rear drop a bit to better clear the body. This requires removing the crossmember, but you're likely better getting it out of the way anyway, no matter what you try.

But that's all just hearsay, as I've never done an auto in the truck myself. These guys will pop back in I'm sure to give any further gory details. But yes, as you're imagining, it's a bit of a hassle.

How bad is it leaking? If it's just a drip, maybe you can get lucky and run a bead of sealant around the seam with your finger? And also check to make sure that all bolts are tight in case something is just coming loose.
If it's a full-on drip that leaves a mess on the garage floor though, it's probably time to pull it apart and put the new one in.
It's not a very substantial gasket as you can see here: http://www.wildhorses4x4.com/product/C4_to_Adapter_Gasket but it still takes just as much work to replace it as anything else in the drivetrain.

Good luck.

Paul

Thank you Paul,

I will try tightening the bolts and then maybe a thin layer of rtv as you said.

 

[DirtDonk]

While it's not the best way perhaps, I've fixed many a small leak with a quick swipe of sillycone.
Even got by without replacing a leaky 9" chunk gasket for a few years once with that method.

When it started to leak again, I used that as a good excuse to open it up completely and do a clean and inspection and install a new gasket. Sometimes 'ya just gotta do it.

Paul

 

[DJs74]

When I did this originally I did mine out of the Bronco, I separated the TC and transmission using my engine stand and the engine hoist which worked good.
Got another opportunity again (different Bronco) due to a transmission rebuild and decided to install the transmission first, then the TC last just for ease and less weight to deal with laying on my back. I made a very crude adapter for my floor jack using a 2x6 and 2x4 cut and fastened together so the TC would sit still and not slide off the jack because they are very NOT balanced. It worked very well but does require perfect alignment and some tugging to get the splines to line up and engage.
Just make sure to support the transmission somewhere before you begin removing the TC because the cross member is what supports the weight and holds everything in place. I used a block of wood between the pan and bellhousing. The transmission cant fall completely down since its attached to the engine but if its not supported, it can and probably will tilt backward until the back of the cylinder heads and/or valve covers hit the firewall.


DJs74

 

[garberz]

If you're gonna pull the transfer case to replace the gasket between the adapter and the trans, leave the adapter bolted to the transfer case. Unbolt it from the trans, that way you won't loose the 13 roller bearings on the input shaft. Just a tip I got from Viperwolf1 several years ago.

Mark

 

[DJs74]

How do you get to this gasket, mine is leaking as well. Do you have to drop the whole transmission?

One of the bolts that fasten the adapter to the C4 also secures the modulator valve bracket (passenger side), I mention that because you might check to make sure the modulator valve isn't leaking, running down and giving the appearance of the adapter leaking.
The modulator has a radial oring seal on it where it slides into the C4 case. Its not likely but possible.


DJs74

 

[diggs00]

Ok want to give update:

Tightened all bolts, one was loose (top passenger side), yet I still have slow leak. I do not have the modulator valve bracket that attaches to one of the bolts. The bolt that is used to attached the bracket looks to be where the leak is coming from. I did notice in my rig that this bolt is a smaller bolt than the other adapter bolts. Is this correct?

Thanks again

 

[Viperwolf1]

Ok want to give update:

Tightened all bolts, one was loose (top passenger side), yet I still have slow leak. I do not have the modulator valve bracket that attaches to one of the bolts. The bolt that is used to attached the bracket looks to be where the leak is coming from. I did notice in my rig that this bolt is a smaller bolt than the other adapter bolts. Is this correct?

Thanks again

All 6 bolts should be the same size.

 

[Tiko433]

There are two types of Modulars ... a "screw in" and "a push in". If you have a "push in " you need the hold down bracket for obviously reasons. Easy to find out which you have . Try to pull it out a little, not all the way fluid will come out . If it won't budge try to unscrew it . I just bolted my adapter on the the other day, all of my bolts were the same size.
This gasket would not be too hard to change.

 

[garberz]

I just bought that last modulator bracket off EBay, those are getting scarce.

Mark