Trans for my 409
- Thread starter RAG 65
- Start date
What kind of car and what's you intentions
If you want a comfortable cruiser 700R4 is an excellent choice, same for a 200R4
RAG 65
Well Known Member
Rag 65 Impala. Cruiser
People say the 200R4 has a better gear range spread than the 700R4. They both can be built to hold up for a cruiser. The key for either would be a cable that hooks to the carburetor throttle with the correct ratio.
Critical for longevity and proper operation of either trans - especially on the 200 4R, is the TV cable adjustment and carb bracketry. Bowtie Overdrives has lots of info on 200 4R and 700R4's.
https://www.bowtieoverdrives.com/
https://www.bowtieoverdrives.com/
Geary Trussell
Well Known Member
If you drive the car on the interstate you will want the overdrive trans.
RAG 65
Well Known Member
Keep the TH350.
Why?
700r4. No adapters needed, no computer controls, easy one 12 volt wire off the brake switch interfaced with a pressure switch on 4th gear in the valve body for lockup. Can be built to handle anything you want and reasonably cheap compared to some others. In your 65 you can also get a detent adapter for the shifter including the plate to show all the gears including OD.
If someone doesn't have an aversion to computer controls,the modern overdrive autos have a lot to offer,you can get stand alone controllers that can be loaded with multiple programs so you can have a nice smooth shifting tranny for your cruiser and switch to an aggressive tooth jarring program if you choose to engage in some stoplight fisticuffs or go to the track.There really is a lot to be said for a fast hard shifting transmission extending life for high performance work but becomes tiresome to explain when out just cruising around when passengers ask "whats wrong with your car".This route does add some initial expense,but also gives additional flexibility,including the ability to outfit it for a paddle shifter if someone were inclined to that sort of silliness.
700r4 is the only way to go if you want highway use and decent miles per gallon. My Powerglide has me at 3100rpm if I want to do 70mph on the interstate, so I just slow down. Spend an extra $500-700 in heavy duty parts and make it handle more than most of our engines can put out. Several well known transmission rebuilders have options for the 700r4 over 1000hp but there just aren't many people bothering with 700r4 for racing because it does cost more, much like the 348-409 engine family builds in general. I have a 700r4 in for building now. Can't wait to get it back, my 9 passenger wagon will need all the help it can get. Another upgrade you can make is to do away with the ultra low 3.06 first gear and switch it to 2.84 so there isn't such a large gap between 1st and 2nd gear. With anything though, it really depends on what you are doing.
I’m doing exactly that a 700R4 in a 66 with a w in front of it. You’ll need what’s in the pictures and youlll have to modify the trans crossmember. The 700R4 is 3” longer than the Powerglide. Since you have a TH350 now somebody might have done this already.
Attachments
As mentioned above you can switch to a 2.84 first to get the gears closer. The sun shell is a weak point because people like to throw the trans in park while backing up before stopping all the way. Then the 4 pinion front and rear planetary sets can be upgraded to the heavy duty 5 pinion but you can buy a 6 pinion if you have more than 500hp.
The faster the shift happens the less wear there is on the clutch linings,anytime there is power transmitted with speed difference between the input and output which means slippage there is wear in the clutches and the attendant heat,so its more about a longevity thing than reliability,for regular street cars back in the day the common transmission issues weren't because something broke it was that one or more clutch packs wore out.It may be different these days but I still think the faster the shift happens under full power within reason,the better.