Why TH400 vs 727?

[Jmos4]

Hi all,

Just curious on to why those who have gone to the 3 speed automatic choose the TH400 vs the old 727, as seen those built to hang a lot of hp, and also believe they are a lighter transmission

Regards,
Jim

 

[Linda's Hell Cat]

I'm not actually sure
But the TH400 is what my SRT8 6.1 installed.
So I'm thinking because there are know supporting parts.

There are way more Hemi parts available for our Hellcats. And there are way more people modifying them to go real fast.

The TH400s can handle the high RWHP.

Linda

 

[Marc W]

The 400 is the most common race trans out there. Many manufactures building them for high hp applications. SFI bell housing and trans cases available for the Gen III Hemi make it a simple bolt on replacement. From a performance standpoint, there are a couple of reasons. The first one being reliability. They can be built to take everything we can throw at it. The continuing developments with the hp90 are heading toward a reliably capable version of that, and from a getting down the track (if properly managed) standpoint, they are every bit as fast if not faster. Another reason I went to the manual 3-speed (T400) is to simplify things. Eliminating the TCM factor from tuning makes makes getting down the track less troublesome for somebody like me that is not a highly experienced PCM/TCM tuner making adjustments after every pass. People figuring out the 2nd gear launch with the hp90 are basically duplicating the gearing I have coming off the line with my T400. Difference is... it’s the tuners that are making that work. The T400 is like racing for dummies.

 

[Jmos4]

Hi,

Thanks Marc for reply, like your build thread, I was just curious as a lot of brand loyalty people out there and most building yours all use the th400 which made me inquire

Regards,
Jim

 

[Magnified]

The 400 is the most common race trans out there. Many manufactures building them for high hp applications. SFI bell housing and trans cases available for the Gen III Hemi make it a simple bolt on replacement. From a performance standpoint, there are a couple of reasons. The first one being reliability. They can be built to take everything we can throw at it. The continuing developments with the hp90 are heading toward a reliably capable version of that, and from a getting down the track (if properly managed) standpoint, they are every bit as fast if not faster. Another reason I went to the manual 3-speed (T400) is to simplify things. Eliminating the TCM factor from tuning makes makes getting down the track less troublesome for somebody like me that is not a highly experienced PCM/TCM tuner making adjustments after every pass. People figuring out the 2nd gear launch with the hp90 are basically duplicating the gearing I have coming off the line with my T400. Difference is... it’s the tuners that are making that work. The T400 is like racing for dummies.

This. Commonality of support, availiability of parts, easy scalability. Reputation for reliability. These factors often out weigh the small amount of additional weight.

 

[Mike L.]

The 400 has no clutch timing involved as does the 727. The 727 has a band for second gear and must release cleanly for the 3rd gear direct clutch to apply. That never happens. There is always a tie-up during the 2/3 shift no matter who builds it. The 400 has one clutch applying on top of another during shifts and does not haft to release anything. Back in the '60s when we were building race transmissions for gassers; the 727 and Ford C6 were good for about 10 passes before it needed a re-clutch. The 400 was good for 60/70 passes or better and shifted quicker for better ET's.