This trans is an old manual valve body build and I'm replacing the direct drum, sprag and clutches. How much clearance should I have between the clutch pack? It's tighter now than with the old pack. Stock HD raybestos 5 frictions and steels.
Preferred spec is .045- use valve spring shims (a .030 and a .015) in four spots around the assembled pack, between the upper friction and the pressure plate and then attempt to put the snap ring in. I assume this is not a transbrake transmission. JW
Not this one, just manual valve body. It has 2 short white springs and to slightly shorter black springs. I'm getting in the .030's with a dial indicator and shooting air to the hub. you can spin the clutches freely by hand released. I think I will try it. What is the best method of burn offs to keep sprag from breaking, 1 2 3 or burn in 3 only?
Burnouts start in second, finish in high. Roll out of the throttle to keep from breaking the converter sprag as the car comes out of the water. 1-2 shift is what breaks the sprag. I would not trust air pressure/and a dial indicator for determining clutch clearance. .030 is pretty tight. You could be ok but I would worry about centrifugal apply with that tight a clearance, when the trans is hot. Keep in mind all the components will grow at operating temperature. JW
1-2 shift is a no-no with a TH400 during burn-out like Jim said. If you have a heavy car making 800+, you may want to skip the HD 34 element sprag and go to the 36-element super sprag and drum from Coan. We've rolled a few 34's in 2 different cars - they just don't hold up. Coan makes some nice stuff. I think the 36-element sprag comes from a Caddy Northstar FWD application.
I'm going to try that 2-3 and just 3 this time. I went back in it to fix a pump bolt hole so I changed the 1st plate to a thinner one and put 4 of the old frictions and one new and have around .045-.050 but I tried to get an angle feuler in there and it is hard to clear the spring retainer. Do they make different gauges to check that clearance on the Direct clutches?
I will ask the parts guy at Transtar to see if he can get a stock one for the 400 I'm going to build later. BTE shows one for 475 that has a different race. http://www.ebay.com/itm/NEW-BTE-Tur...Parts_Accessories&hash=item2337b029a2&vxp=mtr When you build a 400 for a trans break is the procedure the same for most brakes? Where is the best place to go to copy that procedure?
