Hi. I haven't posted on here in a while but now's the time since I started actually working on the car again.
I have a 3.42 posi rear end with a TH350 tranny. I came across a Saginaw 4 speed that might interest me. My main objective is fuel mileage - I would like to do decent highway miles as I won't be racing this bird too often.
I have 2 broken teeth on the ring gear so I'll have to replace it anyways. Should I go with a longer ratio (ie. 3.08) or just keep it as is.
Btw, I bought the car in July of this year & haven't driven it yet since its completely apart from head to toe.
Thanks gents for your input.

I think you should shoot for around the same ratio with a four speed if you are going for MPG. You could go lower numerically but you might find yourself dragging the clutch a little to get started.

Saginaws have fairly low first gears compared to a close ratio Muncie. A Saginaw out of a 6 cylinder car has an even lower first gear. With a 3.36 to 3.42 ratio, these transmissions will quickly get you off the line compared to a closer ratio manual transmission. If you do go lower numericaly, shoot for a first gear ratio of a high 2.00. (Like a 6 cyl trans) V8 Saginaws are around 2.50 first gears.

I had 3.36's with a Saginaw in my 307 69 Camaro it was just right. Decent acceleration with OK mileage.

Thanks for the reply. Also, did you have to 'fit' the shifter or does it go into the floor without any customization.

Thanks

The change over to a manual is not an easy project. With the auto you can run the 3 0's and have a nice cruiser. I've got a M20 and have run 2.79s before. Hard on the clutch but great on the freeway. The other option would be to go with and OD trans and you can have the best of both worlds. With the 4sp I wouldn't go below 3.23s.

For a while I had a Saginaw 4spd. with a 3.11 first and a 2.56 rear end. It came away from a stop sign without having to slip the clutch any more than I would consider "normal".
With that 3.42 that is in the car now, it would be a good candidate for a 5 spd with a .63 overdrive. You could cruise at 70 at less than 2k rpm. and still have real good bite from a dead stop. I did the auto to manual conversion and it is not that difficult. I later switched to a t-5 and that was not to hard either.

You'll have to cut the hole for the shifter as the auto shifter just has a small hole for the cable. I saw somewhere where the dimensions and locations were given. My 69 Camaro is still apart. I can get the dimensions from that if you need them.

Do you have donor car to get the four speed parts from? That makes life a whole lot easier as you won't have to nickel and dime yourself to death by searching for all the little pieces needed for the conversion.

Somethong else: Do a check of the first gear ratio of the transmission you are looking at. It will help you determine which rearend ratio to get. As Hank said, with a low first gear, you can get away with pretty high rearend ratio. Good take off and good cruising RPM. Of course, you will experience a larger dop in RPM btween gears when shifting compared to a "regular" or close ratio trans, but if it's just a cruiser, it won't be like you will be worried about dropping out of the engine's optimum power range each time you shift.

Shifting is fun!

Hank,
Is that T5 one of the "world famous" ones or is it a regular T5? Somebody told me that even the WF ones were only rated for 320ftlbs of TQ. The muncies are supposed to be good for more. Don't know what the sag is good to.

A 4spd shifter from different cars can have different offsets and different placement from front to rear. If you can get a shifter from a first gen. all you have to do in cut the right size hole in the tunnel. I think 2nd gens are probably the same as well. Other shifters may require some mods. The cross member for a 350 and 4spd are the same and driveshaft length is the same as well so there is no problem there. Like Larry said, a donor car makes the whole process a lot easier.

I'm sure the "world famous" t-5 that Firebob is refering to is the world class or WCt-5 that was used in 3rd gens starting in '88. The earlier ones are refered to as non-world class . And yes the torque ratings on the WC's are just over 300 ft.pounds. From what I have heard what kills them is dumping the clutch at high rpms or speed shifting at high rpms. The Muncie is a stronger trans and the six-speed t56 from the 4th gens is stronger as well. The Tremec TKOs can handel up to 600 ft.pounds if you need a tranny that you can really pound on.
I have a WCt-5 in my Firebird and occasionally I break the tires loose from a stop sign and even chirp second gear from time to time. Haven't had any problems with it. I love the crisp shifting and the over-drive 5th gear is great on the highway.