TH400 internal parts - What HP what parts?
 

I just rebuilt my trans a few weeks ago and had been dealing with a local reputable trans builder. I am building another one and want to see what others opinons are on this subject.

1. At what power level would you go to a 6 clutch pack instead of a 5 in the direct drum?
The local guy said he has 5 clutch packs in pro stock cars that have been running a long time with no issue. And the 6 packs create more parasitic load.

2. What power level do you deviate from stock clutches? Local guy told me that if everything is working correctly the stock clutches will break the input shaft off before they slip. (ive done this before :) )

Then again local guy also told me no one makes a forward pattern manual valve body for a th400.

For a 1000-1200hp engine in a 2800lbs car, besides using the older drum with a 34 element sprag, would a stock rebuild and manual valve body be suffice?
All the trannys I see built and for sale advertise basically everything aftermarket and upgraded just to be rated at even a lower power level. Why?

IMO at your power level i would go with 6 instead of 5 clutches in direct and drill a bleed hole in the drum to help with cintrifical force trying to apply the clutches at high rpm and put a hardened input shaft in also. Your pushing the limits of a stock shaft at 800 h.p IMO.

As far as the clutches go the high energy clutches hold up very well. I've never heard of stock clutches breaking the input shaft torque is what breaks shafts.

Trans-go makes a -3 kit to convert a stock valvebody to full manual and it stays foward pattern and comes with stiffer clutch return springs for the direct clutch which is a must.

Also, put a hardened foward clutch hub and install a bearing between the hub and direct drum and get rid of the thrust washer this can be done with some machining or you can buy one already done w/ a bearing.

And make sure he uses a thicker snap ring for the intermediate clutches.

72blwnvrt pretty much covered it all. When I got my tranny built, my builder also said that 5 clutch packs would be fine, but I still told him to stuff as many clutches as he could up in this B&$#@. In addition to that I got the Billet input shaft, 34 element, snap ring upgrade, and my tranny already had a TCI RMVB and a B&M deep aluminum pan.

On a side note... I do NOT recommend this pan. You will be hard pressed to find a linkage bracket that fits it.

B&M Automatic Transmission Deep Pans 20280

Thanks.

I purchased an aluminum pan off ebay for mine, nice solid piece but like you say, I had to cut off the whole side of my linkage to get it to fit.