TH350 and Differential
Drifting
Joined: Apr 2007
Posts: 1,892
Likes: 3
From: Springfield Illinois
Seems to me many go with the 200 4r over the 700r4. In the stock form, a 700r4 is a stronger unit. I am sure it could be a direct bolt in if parts off of an '82 are used. I would have thought more people would have been tempted to go with the 700r4 for the 3.06 first gear.
Thread Starter
Safety Car
Joined: Oct 2006
Posts: 3,930
Likes: 15
From: Calgary Alberta
What modifications are required for a 200r...I just replaced my old bent crossmember with a stock one and I don't want to shell out the cash for an aftermarket one. What modifications are required?
Drifting
Joined: Apr 2007
Posts: 1,892
Likes: 3
From: Springfield Illinois
If thats the case, I would go with a 4.10 or 4.11 (which ever one goes into the vette diff). Based on an RPM calculator, you would be near 7,000 RPMs at 200MPH with a 2004r. You could even go with a steeper gear. A 400 HP engine wont have the power to go 200 MPH.
Thread Starter
Safety Car
Joined: Oct 2006
Posts: 3,930
Likes: 15
From: Calgary Alberta
Have you seen my car yet? It doesn't even have a completed body as of right now...I don't think I'll be able to try out a new tranny and then decide if i need a new gear ratio or not...I need to decide already, I've been putting this off for a while.
http://forums.corvetteforum.com/show....php?t=1849398
http://forums.corvetteforum.com/show....php?t=1849398
Team Owner
Joined: Sep 2003
Posts: 88,393
Likes: 2
From: eville in
add a TQ with 25-2800 stall in that 200r4 and hold on 
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Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Slight mods to the cross member but nothing major. You will need a shift kit if you want to be able to shift into first manually, and you'll need a lock up circuit kit from Bowtie or you'll need to make one yourself.A 2600 converter would go great with a TH200R4 and either 3.36 or 3.55 gears.
Thread Starter
Safety Car
Joined: Oct 2006
Posts: 3,930
Likes: 15
From: Calgary Alberta
My frame is at powdercoat right now...do I have to shift the crossmember brackets on the frame to make the 200r4 fit or am I okay? I am still able to modify my crossmember, but not the frame. I might just have to live with my TH350 and put in a 3.55 gear ratio or higher. I am now leaning way higher to the hard acceleration over the top speed.
Drifting
Joined: Apr 2007
Posts: 1,892
Likes: 3
From: Springfield Illinois
I believe all you mod. is the crossmember, but I don't think it is anything major. I doubt the people that have done the change over have mod. the frame. If you go with a 200 4R and decide to go with a 4.11 or a 4.33, with 400 HP engine that I assume revs to atleast 6,000, I don't see why you would have problem going 160+ MPH. I am sure with a set up like this, you wont be disappointed. At 70 MPH, I cruise at 3200- 3300 RPMS. With a 4.33 you'll turn about 2500 RPMs and a 4.11 at about 2400 RPMs at 70 MPH. I get about 15 MPG on the highway and I am turning higher RPMs. I don't have a lock up converter and my TH400 has more rotating mass than a 2004r, both of which suck more fuel. I truely think you have the potential for great off the line performance without sacrificing mileage (and speed
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).
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Pretty much just the cost of the transmission, and the two small kits.
If you buy a cheap used transmission, you can probably rebuild it yourself for a few hundred. Buying a rebuilt will cost more, and then there are the 'built' transmission that are designed for high HP engines.
The kits are inexpensive...maybe a few hundred for both.
That's pretty much it, unless your transmission didn't come with a lockup converter and you may have to buy one of those.
Thread Starter
Safety Car
Joined: Oct 2006
Posts: 3,930
Likes: 15
From: Calgary Alberta
Damn that is quite a bit of money...especially for an 18 year old! I just talked to Dan at Vansteel - he recommended I go with a 3.55 gear ratio if I am going to use my original TH350. He said it would also be a good ratio if I decide to switch over to a 200r4 10 years down the road. I think I am going to stick with my TH350 and go with a 3.55 gear ratio in the rear. Its a little of a compromise between acceleration and speed. Thanks for all the help guys!
Race Director
Joined: Jan 2003
Posts: 15,175
Likes: 86
From: State of Confusion
Does it matter if I will be using the stock TH350 for the tranny? I want this thing to take off more than I want it to go fast on a straight road - but I still want it to go fast. I guess you have to compromise...I can't decide. A 3.55 will take off faster than a 3.36...but how much faster in speed can you get using a 3.36 over a 3.55?
I have TCI gear-sets in my THM400 that are 2.75:1, 1.57:1, and 1:1 (identical to the 200-4R, without the OD ).
This would make the car 'feel-like' it has 10% more gear in 1st, and 6% more gear in 2nd, while retaining the actual rear-gear ratio for highway driving
i.e. - actual 3.08 rear-gears would 'feel-like' 3.38s in Low Gear and 'feel-like' 3.26s in Second, actual 3.36 rear-gears would 'feel-like' 3.70s in Low Gear, and 'feel-like' 3.55s in Second, etc.
This will help your motor get-off the line quicker/better without reducing top-end MPH/RPM ratios, and probably cost-less than a swap to an OD transmission
Thread Starter
Safety Car
Joined: Oct 2006
Posts: 3,930
Likes: 15
From: Calgary Alberta
I think swapping out the rear gears would be cheaper than swapping out the gears in the tranny...no? I want to rebuild the tranny without spending too much money on new gears. I am willing to spend $300 on the rear differential for a new ring and pinion...I would think new gears for the trnsmission would cost a lot more than $300?
Race Director
Joined: Jan 2003
Posts: 15,175
Likes: 86
From: State of Confusion
I think swapping out the rear gears would be cheaper than swapping out the gears in the tranny...no? I want to rebuild the tranny without spending too much money on new gears. I am willing to spend $300 on the rear differential for a new ring and pinion...I would think new gears for the trnsmission would cost a lot more than $300?
check JEGS, Summit, or Lone Star Racing (in Texas )
Thread Starter
Safety Car
Joined: Oct 2006
Posts: 3,930
Likes: 15
From: Calgary Alberta
I am going to stick with what Dan at VanSteel recommended...3.55 ring/pinion. I'll worry about the tranny when that time comes. Plus, its always a pleasure dealing with the folks at VanSteel - they're the best!
Drifting
Joined: Apr 2007
Posts: 1,892
Likes: 3
From: Springfield Illinois
$1800? I think that estimate is a little too much.. I am sure there are people who have done the swap for under a $1000.. One thing you have to consider is that by going with a TH350 instead of a 2004r you'll shorten the life of your engine.