TH400 mpg with 455 and 200-4r horror stories?

[84GP455]

I have a Pontiac 455 which had a TH400 on it from the beginning of time, great transmission but only has 3 low gears, but then I swapped the rear from a 7.5 with 2.41 to a GN 8.5 rear with 3.42's. Then I couldn't go on the highway with it because it was taching out too much for my engine so I got a GN TH200-4R and what a difference! I can cruise to the beach on the highway now going 80mph and around 2400 rpm. I also have the D5 lockup converter which I wired up and makes the crankshaft a 1:1 ratio with the transmission when going over 45mph. I only had 2.41's in the TH400 but it was still screaming on the highway, so your 3.73's will really make it tach out you won't like it. So far the GN TH200-4R is holding up well under the torque of my 455 and I really like the overdrive!

 

[zeth hale]

Nobody has stated it yet but I don't know how you feel about a 4l80. They are the th400 of the od trans world. You could most likely throw a stock one in and it'd survive until you had money to throw in converter etc. The downfall is you would either need full manual VB or a computer to run it

 

[oldsmobile joe]

my brown calais has a 455 olds, stock from '74, and a 200-4r and 8,5 3.73's from an '85 442. i didn't like the set up. it felt like all my low end torque was being wasted. so then i swapped out the auto for a t56, while better, i still felt like i wasn't using the torque. i didn't use first gear, and second was only used at stop lights. i switched out the gears for 3.42's. much happier now. i now use first gear at stop lights. as for fuel economy, i get about 10-12, but i never tuned it, and i know i run very rich, about 11:1. my goal is to tune it this year or next.
joe

 

[foxtrot]

I think that you also need to factor in the amount of abuse that you're planning on delivering to it. For example, if you're planning on driving it on the street like an adult with the occasional burnout; I'm thinking that it's not required to acquire one that is built with all of the expensive upgraded parts. I'm thinking that one of the mildly upgraded 'stage-2' 200-4R units would be plenty good enough for that use case. Those units can be had for under $2k.

 

[QS442]

I think that you also need to factor in the amount of abuse that you're planning on delivering to it. For example, if you're planning on driving it on the street like an adult with the occasional burnout; I'm thinking that it's not required to acquire one that is built with all of the expensive upgraded parts. I'm thinking that one of the mildly upgraded 'stage-2' 200-4R units would be plenty good enough for that use case. Those units can be had for under $2k.

Where are you seeing these units for under $2k?

 

[QS442]

I have a 200-4R behind my 455 and it dident cost 3400 bucks I built it myself with parts from David huseck in New York it shifts nice I eliminated thee lock up so it's just a four speed 342 gear in the rear I run a lighting rod shifter I like it a lot ied build another one

Interested in getting more info regarding your build. I contacted David and his price was $3400 not including his converter. I'm open to buying the right parts and getting it build locally (I never built a trans) if that's cost effective. I have a few cores that I can use. He advised the billet build to handle the 455's torque numbers but after the $$ i put into the 455, it just isn't in the cards for me right now.

 

[QS442]

I have a 200-4R behind my 455 and it dident cost 3400 bucks I built it myself with parts from David huseck in New York it shifts nice I eliminated thee lock up so it's just a four speed 342 gear in the rear I run a lighting rod shifter I like it a lot ied build another one

Interested in getting more info regarding your build. I contacted David and his price was $3400 not including his converter. I'm open to buying the right parts and getting it build locally (I never built a trans) if that's cost effective. I have a few cores that I can use. He advised the billet build to handle the 455's torque numbers but after the $$ i put into the 455, it just isn't in the cards for me right now.

 

[QS442]

I don't think you would like the cost but you could go with a TH400 and a Gear Vendors overdrive and have both a bullet proof setup and the benefits of overdrive.

I looked at this option, however I've heard mixed reviews and it is pricey. I would prefer to put the $$ into a 200-4r.

 

[QS442]

I have a Pontiac 455 which had a TH400 on it from the beginning of time, great transmission but only has 3 low gears, but then I swapped the rear from a 7.5 with 2.41 to a GN 8.5 rear with 3.42's. Then I couldn't go on the highway with it because it was taching out too much for my engine so I got a GN TH200-4R and what a difference! I can cruise to the beach on the highway now going 80mph and around 2400 rpm. I also have the D5 lockup converter which I wired up and makes the crankshaft a 1:1 ratio with the transmission when going over 45mph. I only had 2.41's in the TH400 but it was still screaming on the highway, so your 3.73's will really make it tach out you won't like it. So far the GN TH200-4R is holding up well under the torque of my 455 and I really like the overdrive!

Did you get the GN 200-4r built?

 

[1bad79]

Interested in getting more info regarding your build. I contacted David and his price was $3400 not including his converter. I'm open to buying the right parts and getting it build locally (I never built a trans) if that's cost effective. I have a few cores that I can use. He advised the billet build to handle the 455's torque numbers but after the $$ i put into the 455, it just isn't in the cards for me right now.

Maybe prices have gone up? I started with a czf core that helped, a lot less to buy,I think I spent 2500 with the converter? But if your having him do the work your going to pay more I did buy those parts 3 years ago I dident think it had been that long