Car: est 4200 lbs w/ driver, 455 Stg 2, 3.73 rear, 30" tire. Intention : 500 HP, 95% street, 5% strip. I prepped my '70 THM400 for an UltraBell, and the crossmember is set-up (if I have to change these around- no big deal). No driveshaft yet. According to online calculators, the THM400 will be turning about 2580 @ 60. I replicated this in my Duramax, which with overdrive OFF, also turns about 2500 @ 60. I realize some of the difference is the diesel being a lot closer to redline there, but the bottom line is... after 15-17 years of driving overdrive-equipped vehicles, I don't think I will be comfortable with nearly 2600 RPM @ 60 (not to mention wear & tear, etc). Can you guys school me on the suitability of 700R4 vs. 200-4R for these specs? I'm not finding a clear answer on this 'out there'. Thanks
well this was the same decision I wrestled with.. the 700r4 is heaver and requires a adapter, the gearing in the 200r4 is a bit steeper but not as strong. There a dozens of gear ratio calculaters that would forcast what rpms you would be turning with tire sizes included. I've decided to do a six speed manual. Just need to find a good core for rebuild. With the assumed lighter weight, less of a loss of hp and fun factor...I just got tired of the debating within myself and being told the 200r4 would have to be BUILT to last and tv cable issues....o No:
Most guys use a 2004R. It doesn't need an adapter, and the gear ratios are better. The 700R4 has a nice steep 3.06 first gear, but the spread to 2nd is big (1.63), so it isn't as good for performance. The 2004R is 2.74, 1.57. Either transmission will need to be beefed up considerably to be reliable behind a 500 HP BBB, especially at the track. Another option is a Gear Vendors Overdrive. That is the route I took. The GV is rated at 1200 HP, and has a .78 ratio. With your 30" tires, you would be at 1955 RPM with NO converter slip. http://www.gearvendors.com/
There is another option. Convert your TH400 to switch pitch, and change your axle to something like 2.56 or 2.73:1. It won't save as much gas as a lockup trans, but its a lot stronger and a lot easier to do. Bruce Roe
Another option is the 4L80(E). It is the equivalent to the THM400. Your choice of trans all depends on your capabilities, $s you want to spend, and what you want your car to do. For me, I made it simple, if the car had a THM400 then the equivalent OD trans should be it's replacement...in the world of GM, with this logic, it is 4L80/ 4L80E/ 4L85E. Other board members have had success with the 4L60(E), 200 4R, and 700r4. Plenty of info, do a search with in this section of the forum. fwiw Your Duramax likely has a 4L80E behind it.
Ideally, the 4L80E would be my first choice, but the cost factor is considerable here- my budget is not open-ended. Likewise, the GV route is also pricey. I have read thru the forum, was hoping by posting my combo I could get more targeted opinions. thanks for the input, I certainly will weigh all suggestions. BTW : my DuraMax has the Allison 1000, 5-spd version. EDIT :: I got a line on a freebie 4L80E (for a core), but I read around that the Ultrabell will not bolt on- the bolt pattern is different & the pump facing is not flat. There are a few manufacturers offering machined adapters, but now this is looking less desirable/more expensive still. So... still fishing for the answer...
If you still haven't ruled out the 4L80E I've attached some info for shifting. If you search on posts made by me and do a little diggin into what I've done you will likely find all the info you need. Regarding the spacing and adapter, when I bought the BOP plate it came with spacers/washers for the flywheel. Based upon your original post it looks like you will take your car to the track, I can't speak to the track rules because I have never gone down the track, so I do not know if spacer between the flywheel and TC are acceptable. I drive may car pretty hard at times doing WOT through gears 1-3, and let off before I go into 4th because I am well over the speed limit by then:3gears: I've got over 400 miles on my setup now and haven't had any problems, but I'm just one guy. If you have any questions regarding my set up please feel free to send me a pm. I'll do my best to answer them. Here's one link...go to post 44 and take a look at my .pdf file regarding install. It has most of the details for a riv install and may aid with your decision. http://www.v8buick.com/showthread.php?157013-nother-1970-Riviera-owner&highlight= Attached to this post is info about shifting if you don't want to go with manual shift valve body. Click here -> View attachment 4L80E is the way to go.doc I built my own TCM, my education is in this area of electronics so it wasn't a big cost factor. good luck -Chad
Be prepared to spend a minimum of $1500 for a "decent" 200-4R. If you want to drive it like an old woman you can do it cheaper, but either way it is not cheap. Torque converter selection factors in too, if you have much of a cam then the D5 type core might not work without creeping at the stoplights; leading you to a fairly spendy converter. I invested about $3000 in my 200-4r 10 years ago and it still works. I still don't trust it to last and since my builder has retired I don't know where to take it for fixing. Wherever it goes, it will have to go in a box and be shipped as 200-4R builders that know what they are doing (most of the time, anyway)are few and far between. Even the best builders sometimes have a cursed trans it seems. Unless you have a guy that is local and has a good reputation with the 200-4R I would think twice. And pay the extra to have him do the install so you aren't stuck with the R&R if there are issues. It's a great trans on paper and better when it works right, but when it doesn't :spank:
Let me ask this question flat out :: would a mostly street-driven car turning 2500 RPM @ 60 be something you would find acceptable?
Depends on where you live Mark.. For instance.. I used to live in the city, shop in the burbs.. so lots of 30-50 MPH speed limits in a normal "drive to work" (or anywhere else for that matter) situation. But now, I live in the country.. pull out of my driveway, and the limit is 50.. and my percentage of freeway driving has gone up dramatically. No big deal in my daily driver with OD, but in my suburban, with it's Buick 455 TH 400/4.10 rear gear.. it's night and day. Drives me crazy to drive it down the freeway that far. Empties the wallet quickly. Used to not care when it had a 10K pound trailer behind it, but now, just empty, going to the dyno shop, or to drop a crate at the truck depot, has me really eyeing that 700 I have sitting on the shelf.. Thus far, I have been too busy to worry about it, but if I decide I need to keep commuting back and forth with it (130 mile drive) then no doubt, it will have the OD trans in it. But it never bothered me in town that much. JW
That was pretty much my threshold - 2500 RPM. Speed limits on the highway here are 65 & 75MPH so the THM400 w/ 3.42 on the rear and keeping up with traffic put the engine well past 2500RPM. Now, when I want to travel down the highways I can do so without feeling tense about the folks not paying attention because I am now going with the flow while not paying a fortune for fuel. If you and your situation hold yourself to 2500RPM / 60MPH then I would keep the 400.
Like I stated above, I don't care for 2500-2600 @ 60, but assuming I get the Buick onto the freeway here & there, I like to go 75- thats around 3200! At this point, I am just completely accustomed to OD revs. The Buick will be a pleasure car only- no daily commutes. Still absorbing info, but so far am totally depressed on the cost of an OD auto built for 500 HP. Guess I need to start a dedicated 'Trans Fund'...
I would swap to a 3.08 gear and keep the cash in your pocket.... You have lots of torque to move the car off the line without the 3.73 gear... I am using a 3.42 gear, 30" tall tire, TH400 and I am happy with the RPM I will have on the highway. Part of the reason I am happy with the RPM is that I am using a switch Pitch Th400 with a 3200 high stall and 1800 low stall. This saves me about 200 RPM on the highway, less fuel used, and best of all less heat and wear on the engine and trans due to less slip in the converter. The reason I picked the 3.42 gear over the 3.08 is so I would get the RPM up a bit so the turbos would be spooled up a bit at cruising speed and ready to go when I floor it. With a 3.08 gear and the 30" tall tire with the th400 you would sit at about 2200 RPM at 60 MPH and 2700 at 75 MPH... If you are not racing the car then use a 2.73 gear and you would be at about 1950 at 60 and 2450 at 75. I would be sure to use a failrly tight converter to keep the slippage down or the RPM will be a little higher.
It still wierds me out to only hear the trans shift twice with my ST-300, i keep waiting for that 2nd -3rd then into OD that I was so used to with my truck! I have the 2.73 rear in my car, and though I'll never win any races it's great with the set up i have. Its fine for just cruising around and it gets bearable mileage even at 60-65. I drive my Buick to and from work every day as well.
I don't think at the power level you are talking about you can do it cheap. I have a 700R4 in mine but I don't beat the snot out of it with sticky tires and it has been fine for 5 years. On the other hand, I have a buddy that beats the snot out of his car, he finally went to a 4L80 and no more problems. He was going thru 700R4's on a regular basis, they were built by him with special parts and they still wouldn't hold up. He said the internal parts of the 700R4's and the 200R4's don't compare to the 4L80 for strength and durability. I think he runs a Compushift box on his setup. Mike D.
Big Power + Heavy car + Racing Conditions + Sticky tires = maximum stress on the transmission and the rest of the drive line. The weak link will always reveal itself if you race the car. The 200 and 7004R transmissions were never meant to stand up to 500 ft lbs + of torque, hooked up solid at the track. They can be modified to take the abuse, but you pay for that. If you intend to use the car as a cruiser, and never race it, a modestly built OD transmission will be fine on the street if adequately maintained and cooled.
Your car/setup sound very similar to mine. I went with a 200-4R that I had Janis Transmissions in Akron, OH do for me. Vince Janis really knows these transmissions. He's big into the GN stuff. I've had no problems after 4 years. And I love it. No electronics needed either. Goes in pretty easily in place of the old th400. And just to let you know, I ended up spending a total of right around $3500 to have the trans built to withstand my engine and the weight of the car. Plus the couple of extra goodies you'll need like for the TV cable, an 11x11x1.5" aux. cooler and other misc. I have a thread here documenting the install. For a 200-4R trans, three names always rise to the top: CK Transmissions in NJ (Chris), California Performance Transmissions (Art Carr), and Janis Transmissions in Akron, OH (Vince). Check over on one of the turbo boards.
