TH350 swap to 200 4r?

[hyarbour]

How much did this project cost? (trans rebuild, switches, etc)

[chevydog66]

Foosified, yes the spring comes with the TVEZ kit.

[chevydog66]

Cost was $1050 total. $150 for the used trans. $210 for parts from www.bowtieoverdrives.com, and $689 to rebuild supposedly good trans. The TH 350 that I removed only has 3000 miles on it. It was a fresh rebuild last year with good firm shifts and higher stall convertor. So I can sell it for $300 and recoup some of the cost.

[Foosified]

Thanks Chevydog66!

[mnunn454]

Originally Posted by chevydog66

Cost was $1050 total. $150 for the used trans. $210 for parts from www.bowtieoverdrives.com, and $689 to rebuild supposedly good trans. The TH 350 that I removed only has 3000 miles on it. It was a fresh rebuild last year with good firm shifts and higher stall convertor. So I can sell it for $300 and recoup some of the cost.

Let me see if my math finger still works.

$1050 total cost, Minus $300 for selling the TH350
Equals $750 invested

With the 3.73 gearing the mileage couldn't have been good. So I'll estimate with the overdrive you're getting 30% better fuel mileage

Estimated consumption of 18 Gal (1 tank) per week at $2.75 per gallon
means $15/week saved.

Equates to payback of 50 weeks (less than a year).

Not bad, Not bad at all

[chevydog66]

I'm pretty sure my truck has a 3.07 or 3.08 rear gear in it.

[mnunn454]

Sorry Chevydog66. I saw tkeduk8r's reference to 3.73 and thought it was yours.


Personal opinion here but the 2.15:1 ratio in high is going to be lugging the engine at most highway normal driving. Ideally 2200 RPM at 55 and 2300 to 2400 at 70 is usually about normal.

An eventual change to 3.42 rear gears might help bring it into a better range.

Congratulations on your install. My Elky has a TH700 with a 3.55:1 rear end and I think it's the perfect setup ratio for both ends.

[chevydog66]

So you think the cruising rpm is too low? And that's not good on the motor?

[jondancer]

Subscribed

[BCOWANWHEELS]

You want a 30 spline not 28 in these

[External]

Hey everyone, in post #23, where does that red wire connect to??
Mine has all those wires just cut.

[LockDoc]

-
I put one in my '69 Suburban with a crate 350 and it worked out good. The first 2004r was a freebie and had problems, so I went to the salvage yard and picked one up and it was a good one..... I used the BowTie Overdrives components to make everything work correctly and it was pretty straight forward. The only thing that gave me any problem with the install was setting the pressures correctly. They are critical. The only reason I had trouble with that was because of my inexperience.

I originally had a 3.07 rear gear and it was too tall for the setup I had. The trans overheated and blew the trans fluid past the front seal. I switched it to a 3.73 I had on hand and had no more problems.

LockDoc

[jocko]

Originally Posted by chevydog66

So you think the cruising rpm is too low? And that's not good on the motor?

chevydog, yes, generally speaking, 3.08s with an O/D are not exactly a great combo at general highway speeds (65-ish and slower) due to the potential of lugging the motor. I probably wouldn't worry too much about it down to 1800-1900 cruising rpm, but if you're routinely cruising at 16-1700, or even lower, rpm on the highway, probably too low. Your low profile tires will probably help this situation and you might be ok. But the 1300 rpm at 50 mph comment does concern me.. Remember to use a GPS to confirm your speedo after all these changes. Here's a chart that will help you see what you can expect for RPM at various speeds/tire diameters with your 3.08s and also with 3.73s. This is why 3.73 is the sweet spot for most O/D transmissions.