As the title states, my 400 is painful soft with this cold weather that's come in. The health of this transmission isn't in question, it's a fresh unit and im absolutely sure I got it right build wise. The question i have is, being that I used scarf cut rings on the center support....as well as the pump, could it be that the internals need time to expand to create a good seal...or is it my fluid choice? I'm using Dex/mercon. When the transmission gets some heat in it after a few miles....it gets right and shifts like a rmvb fixed line pressure 400 should.

 

I'm not experienced enough with transmissions to be able to answer your question on the scarf cut rings, but I can tell you my 400 is still basically a standard rebuild with borg warner clutches and a turbo action reverse full manual valve body installed and deep pan and big cooler, and I use Fuchs Dex3, no matter the weather (and it's been very cold here near zero some mornings) it always shifts extremely fast and hard

 

Thanks for the input. Wish I knew what the cause was, it's like this transmission likes heat for some reason. Usually it's the opposite, heat brings issues.

 

The center support seals do not affect 2nd gear. The seals on the pump are for the Forward Clutch which would cause delayed garage shift into forward gears.

Don't really want to throw out guesses here......Install a pressure gauge & see if it's lower when cold.

Did you "calibrate" the dip stick? Low fluid level can cause this.

 

No, didn't calibrate the dip stock. Yes, I knew the intermediate is fed through the center support bolt.... but out of ideas I threw the scarf cut rings into the mix. I've checked the fluid level hot many many times....all looks well. I know the filter level/placement is perfect, just scared to overfill it as I know that can be almost as bad as underfilling it. The stick I'm using is a lokar peice. I guess I could temporarily overfill it just to see if she tightens up while cold..... doubt really know what else to do.

 

Pull the pan & MARK where the dipstick is in relation to the Pan Rail with a straight edge.

 

On a side note, where do your trans temp's usually sit? I'm seeing 180 degrees trans temp on the highway after cruising for more than an hour.. . I think I should put a fan on my trans cooler. I don't see it needing to run at 180. My engine coolant temp doesn't even go over 170.

Also what trans filter are you using? I use a steel mesh gauze filter, not paper.

 

I use the paper filter that AutoZone carries. As far as temp.... not sure as I haven't put a gauge on it yet. I've shot the pan with infrared temp gun and it's been 180-190. Seems this transmission shifts best when it's good and hot....weird for sure.

 

You could try the TCI mesh gauze trans filter like I have, see if it improves oil flow when cold.

I think this is the one. I bought I so long ago I forgot if this is their steel mesh one or not .. https://www.summitracing.com/int/parts/tci-228500

edit: looks like it is the one, just read the comments.. "It looks the same as the standard filter, but has the premium high flow bronze screen instead of fiber filter media"

 

Thanks. Wil likely use one when I change the fluid.

 

Did you ever figure out what caused the soft shifts before the direct clutch hub let go?

 

I didn't, before it let go. But as I was building it this time, I used a screen type filter instead of paper. Rock solid at all times now

 

Gotcha, good to know! I used the scarf cut rings on the center support and pump also. Was hoping that had nothing to do with it.

 

Are you having issues?

 

No I'm not having issues, I was just wondering because I also used the scarf cut rings on my first TH400 rebuild. When I get it in the car hopefully all is good.