[jimsmonte80]

I am in the process of building up a TH-350 for a street car. I had the pistons machined for the direct and forward stack to accept 5 clutches. Would it really be a performance increase to having the low/reverse clutch piston machined to accept a 5 clutch stack? My understanding is, when you shift into manual low from a stand still, you will have the low/reverse roller holding and the low/reverse clutch applied and holding. So 1 extra clutch disk should not help much with holding in manual low, but cause more drag on 2nd and 3rd?

And so I don't have to make another thread, I have a question on front clutch stack clearances. B&M specs .015 - .030 (.015 seems too tight), another spec used .020 - .040, a MOTOR manual says .010 - .090 (pretty wide range). Any thoughts on clearances used that work well with good clutch engagment and little forward creep in neutral?

[jakeshoe]

What application do you plan to use the trans for? Max RPM? What valve body?

The rule of thumb is .010" per friction and it's a pretty safe one but not always the absolute.

The larger diameter of the intermediate clutches necessitate a bit more clearance IMO. .015-.020" per friction is good.

A transbrake, offroad, or extremely high rpm combo may need a bit more clearance all around.

The forward clutches can be pretty tight, as they are not a shifting clutch. .020" total play will work but may creep in neutral. .070" will work fine too.

I set the directs at .050-.070" depending on clutch count and application.

I would just run 4 low/reverse frictions as long as it's not a transbrake application.

[jimsmonte80]

Street car with 425 hp, 6500 rpms, 3000 stall, b&m valve body mods (spring changes). I figured .020 on the forward clutch should be fine. I was more curious about the low/reverse clutch stack. Looking for confirmation that the low/reverse roller and clutch will be holding in manual low range. Thanks for the reply!

[jakeshoe]

Yes L/R holds in manual low.

[jimsmonte80]

I looked at my automatic trans motor manual which had an operation power flow chart. This explains that the low/reverse roller is holding in auto drive and manual low. Shift in manual low, and now you have the low/reverse roller and the low/reverse clutch applied and holding. Conclusion is, 5 clutch stack over a 4 clutch stack should not provide that much, the possible drag on 2nd and 3rd in having a 5th clutch could be worse on the trans for my application.