Questions before switching from a 200-4R to a TH 400...

[toofastforyou]

I still have my GN's original 200-4R transmission which was "bullet-proofed" several years ago by Eric Schertz @ Dynotech, with some billet and hardened parts, plus a trans brake, and it always performed flawlessly. Since I do drive my car on the street, having an overdrive is really nice to keep the revs down, especially when getting on a highway. The only thing I don't have is a lockup converter.
Last year, I bought a complete Stage II engine which will make a lot more power than the one I previously had and everyone is telling me that the 200-4R won't last, even if built with all the "good stuff" in it, and that I should start thinking about switching to a TH400. I know that a TH400 is made stronger and will probably handle my motor's power more easily than a 200-4R, but I have several questions before doing a switch:

-1˚: Why is it that everyone who put a TH400 has to have a "reverse pattern manual valve body" ? Isn't it possible to have a TH400 with a FORWARD PATTERN and AUTOMATIC (NOT manual), valve body + a trans-brake? I don't think it would be fun driving the car on the street with having to constantly shift up and down at every stoplight or whenever traffic slows down or gets faster... I don't really like that idea...

-2˚: Since the TH400 doesn't have an overdrive, would it be a good idea to use 3.23 gears to compensate for not having the overdrive ?... Also, would that hurt my 1/4 mile et ?

-3˚: To install the TH400 under the GN, what kind of crossmember is needed (from what kind of car) ?...I also think the driveshaft will need to be shortened too, but I have an aftermarket aluminium driveshaft with a Mark Williams heavy duty trans yoke and I hope it will be possible to have it shortened and reused, but I dunno about being able to reuse the same yoke though (200-4R vs. TH400)...
As for the shifter, I already have a B&M "Pro Stick" shifter and all I would have to do is to change the gate in it and I'd be ok with it.

I know that's lot of questions at the same time, but I'm trying to gather the most information possible before actually taking the decision to jump in and do the switch...:redface:

thanks for your replies,

Claude. :wink:

 

[SGRIM]

How fast do you plan to go?

How often do you plan to race?

Don't give up on the 200 just yet, just IMO

 

[toofastforyou]

How fast do you plan to go?

How often do you plan to race?

Don't give up on the 200 just yet, just IMO

With the new engine I have, Jack Cotton estimates I should be able to go mid 9's (at least!)...

I do race it every now and then, but not every weekend (I'd say 1 weekend out of 4...)

Don't get me wrong...it's not because I don't like the 200-4R...I DO like it!...but... I'd rather sell it complete (I have two Art Carr converters for it too) rather than to wait until it blows apart and having to rebuild it PLUS also having to switch to a TH400!...

Thanks for replying...

Claude.

 

[Scooter3800]

1: Why is it that everyone who put a TH400 has to have a "reverse pattern manual valve body" ? Isn't it possible to have a TH400 with a FORWARD PATTERN and AUTOMATIC NOT manual), valve body + a trans-brake? I don't think it would be fun driving the car on the street with having to constantly shift up and down at every stoplight or whenever traffic slows down or gets faster... I don't really like that idea...

I was also in a similar situation - I wanted to be proactive and get rid of the 200-4R while it was still in good working order. I don't drive my car a whole lot, but when I do its nice having a piece of mind the trans will not be the weak link. Yes, I do miss overdrive, but that's for another thread...

I do not have a reverse manual VB in my trans - and never will. My TH400 shifts on its own! I also do not have a transbrake.

2: Since the TH400 doesn't have an overdrive, would it be a good idea to use 3.23 gears to compensate for not having the overdrive?... Also, would that hurt my 1/4 mile et ?

I would leave the gears alone and run a taller tire.

3: To install the TH400 under the GN, what kind of crossmember is needed (from what kind of car)?...I also think the driveshaft will need to be shortened too, but I have an aftermarket aluminium driveshaft with a Mark Williams heavy duty trans yoke and I hope it will be possible to have it shortened and reused, but I dunno about being able to reuse the same yoke though (200-4R vs. TH400)...
As for the shifter, I already have a B&M "Pro Stick" shifter and all I would have to do is to change the gate in it and I'd be ok with it.

You can use the same crossmember that's in your car now. You'll have to either modify your trans mount for the TH400 or buy one made for the swap. Yokes are different between the two transmissions - TH400 obviously being larger, more splines.

 

[toofastforyou]

Thanks for replying...

In my case, I do need a trans-brake...So I'd like it if someone could tell me if it's possible to have BOTH a forward shifting pattern AND a trans-brake?

As for losing the "overdrive" function, well it's my second priority concern.I thought about the 3.23 gears to compensate...I also have some 28" tires on the car and it's about the tallest I can stuff in the stock wheel openings.

About the crossmember, if I can still use the original one, well great!...It's just that I thought it had to be replaced with one off another car model...you are saying that you can "buy one for the swap" ?...From who, please?...

As for the driveshaft and yoke, well it's the last detail that worries me. I will probably have to get another one from Mark Williams and maybe have my aftermarket driveshaft shortened...

thank you,

Claude.

 

[quickt]

We don't do anything in forward pattern. ATI might still do a forward pattern. We can do Auto Shift Transbrake for TH400 but really prefer not to. You will miss your little 200 if you drive it much.

 

[overkillphil]

3.23's won't compensate for a lack of OD IMHO. As a reference, you would have to put something along the lines of a 2.41 R&P to get similiar OD cruising rpms.

If you are just trying to "minimize" the effects of no OD with the 400, 2.73-3.08 would do that, but kill the performance of the Turbo V-6, esp. out of the hole.

 

[toofastforyou]

Thanks guys for your comments...I just wrote a new thread asking about a 4L80 transmission which is supposed to be similar to a TH400...

Thanks,

Claude.

 

[toofastforyou]

We don't do anything in forward pattern.

Lonnie, is there a particular reason for that?

We can do Auto Shift Transbrake for TH400 but really prefer not to. You will miss your little 200 if you drive it much.

Can you explain a little, what is a "Auto Shift Transbrake", please?

Thanks!

Claude.

 

[Otto J]

If you are only planning on mid 9s I would test out our 2004r before swapping to a 400.
We plan on really putting the 2004r to the test on Bretts 109 motor(71HPS 4 bolt ) and Bill Szablweskis 109 (67HPQ 4 bolt) with a Precision turbos that should put them both easily in the mid to low 9s.
First we will see if it survives the dyno
Mind you if you plan on hitting mid 9s EASILY consider dumping thos ART Carr convertors and call Dusty.

 

[quickt]

Lonnie, is there a particular reason for that?



Can you explain a little, what is a "Auto Shift Transbrake", please?

Thanks!

Claude.

Same concept as a 200 with a brake. The trans shifts automatic like normal with electric transbrake operation in manual low. Put it in drive it will make all the shifts like a stock 400.

If your goal is 9.50 the 200 will handle that task. With our Billet aluminum VB in development we believe low 9s will not be an issue. You will see a TSO car this year make 8 second runs with the 200.

We dont like to build them because they are a PIA. I cant sell a kit for someone its too complicated. I need to build the unit. The transbrake is average operation nothing fancy. You give up some reliability compared to the Manual VB units.

 

[KL Mallender]

Forward shift/Auto shift 400 with a "Brake"?

For the life of me, I can't imagine someone doing such a thing when everything else is doing it backwards
I believe Lonnie and Chris might know someone who tinkered with such an animal, but after all the beating's lately from such a minority group, I wouldn't be a bit surprised if they smile and say "NO". just not worth the headache's, IMHO.

Kevin.

 

[quickt]

:smile and say "no". Just not worth the headache's, imho.

Kevin.

exactly!!!!!!