jakeshoe

The BRF valve body is one of the preferred units. I have an extra BRF valve body if you have trouble locating one (they are somewhat rare). The CZ valve body from a Monte Carlo SS is supposedly better for a NA application as it has a little less active kickdown but the same WOT shift points. There are other good valve bodies, and there are valve bodies that can be made to work, but it is less of a headache to get a decent WOT and part throttle shift point using one of the performance valve bodies. The 200-4R is WAY more capable of surviving power than a 700-R4...

Also of interest, a short shaft TH350 weighs almost exactly 125 lbs sans converter. A short TH400 weighs about 10 lbs more, right at 135 lbs. A 4L80E weighs 178 lbs.

200-4R, TH400 and 4L80 comparison. A pic is worth a thousand words...

Th parts are listed in my post... 500 hp and a 700 don't go together well, if that is your ultimate goal, use a different trans, 200-4r or 4L80.

Totally blocking the accumulators on a 700 is not a good idea. A 700 with a "Vette" 093 servo and a mild valve body kit will shift to 2nd HARD at throttle. I coached a guy who has never done any trans work through a Transgo Reprogramming kit install about 2 weeks ago, he went with the firmest shift settings and is now wanting to back it out a bit as the 1-2 is VERY firm. Blocking the accumulators for harsh shifts is asking for hard parts failure. I wouldn't buy a transmission off Ebay unless it was a local business that you can do warrantee work with. A good 700-R4 would cost at least $1000. I quoted a rebuild for $1000 last night actually, it requires over $550 in parts at my cost to build one properly. This should give you an idea of what you will be getting for some of the prices on Ebay... $200 for a rebuild kit with good clutches and the updated 3-4 clutch kit. $45 for a good sun shell $35 for a 13 vane pump kit $30 worth of TV boost valves $10 for good pump rings $75 for a valve body kit $25 for a good band $4 for the filter $20 for the TV cable $20 for the buishing kit $20 for the thrust washer kit plus tax...electricity for the shop, consumables, and paying for someone who KNOWS what they are doing and will do it right to put it together. You're not getting into a GOOD overdrive transmission for cheap.

Scottie, I'm not trying to be argumentative here, I'm trying to explain a widely misunderstood auto trans power consumption myth. let me know if I'm explaing this in an understandable fashion. I'll use your quote: OK, Me or you might not FEEL a HP loss in the 6000 rpm launch scenario you mentioned. However if we did back to back testing of either a TH350 and Th400 or a TH400 with lightweight parts vs. a stock TH400 especially if we did it on a dyno THIS is the scenario where we would actually be able to measure the difference. The 2200 launch scenario is probably not going to spin the rotating parts up so fast because it doesn't have to go from a standstill to 6000 rpm like in the other scenario. Even though the parts spin up much faster (in the 6000 rpm launch) and the DURATION of the HP loss is less, the actual amount consumed would be MUCH greater than the 2200 rpm launch because the HP consumed increases exponentially with the rate of acceleration. The 2200 launch would spin the parts up slower (not as much instant rpm, and most likely also simply a slower car), the slower rate of acceleration uses much less HP although over a greater duration or length of time. The overall outcome would still be less power loss overall with the slower accelerating combo ( lower rpm launch).

How is the converter going to effect spool up of the transmission parts? If you have a 6100 converter, when it flashes, if the trans is still at 0 rpm, it would have to spool up quicker....costing more power. The QUICKER you spin up the parts, the more power it consumes. This is why I have mentioned, worrying about a few lbs of rotating weight in a car that isn't running 10.0's or faster is splitting hairs. However the sub 10 second cars will see a difference because they accelerate fast enough that there may actually be a measurable loss, on a dyno or in ET. Let's put it this way, Grandma's 17 second boat on wheels isn't accelerating fast enough to matter. My mid 12 second Chevelle isn't either. A mid 9 second car would probably actually see a consistant ET loss with the added 5-6 lbs of rotating weight, 15 lbs of overall, and the .04 gear ratio differential, but it would probably be around a .1 in the 1/4 based on what I have observed. So grandma's car might have lost a HP, the 12 second Chevelle might have lost 5, and the 9 sec ride might have lost 25 hp. The power loss will increase exponentially, but doesn't have an effect until you get to a certain level.

Comparison shot of 200-4R, Th350 and Th400.

Pic above, TH400 is on top, short shaft, Th350 is the lower unit, also a short shaft.

You are probably correct on the lengths for the Long tail TH350 and mid length TH400, however try to find a 13" tailshaft Th350...they were rare to begin with, now after being out of production for 20 years, they are virtually impossible to find. I actually don't believe I've ever seen a 13" tailshaft TH350 in my 14 years of rebuilding transmissions.... And as stated earlier you wouldn't want to run that long of a tailshaft in the cars we are speaking about for driveline angle reasons. A short shaft Th400 and Th350 are approx 5/8" different, I measured tonight to refresh my memory.

TCI's website is a good reference and fairly accurate. let me ask you a question here, you seem to be distrurbed that I am correcting you. First, We have a potential audience of thousands of other enthuisiasts. You are trying to help them by posting information, however if you post incorrect information you haven't helped and have potentially cost them more money. I have alot of experience as a mechanic and hotrodder. Several years of experience working in private shops or dealerships. I currently work for an OEM automotive manufacturer. I also have quite a bit of automotive machining experience. I'm certified by ASE as a Master Auto Tech and Master Gasoline Engine Machinist, my master auto tech is a recert, so I've been certified for almost 10 years now. I would be considered an automotive repair expert by most people. However there are still people out there who know alot more than I do, or alot more about certain aspects of autos. My "specialty" or what I concentrate on now is mostly GM automatic transmissions for high performance applications. This is what I do as a "hobby" and side business. So yes I do know a little about the subject we are discussing. Now back to the specific discussion we are on, We are dealing with Datsun Z cars that have a fairly short wheelbase. My 260 with JTR mounting and a SBC/ short shaft TH350 combo has a driveshaft center to center length of 22". That's pretty short. Nothing wrong with a short driveline but you can start to have issues if you get too short, driveline angles. I wouldn't recommend using a mid or long length transmission in the Z car unless you had a specific reason for doing so and know how to properly set the driveline angles.

Gonna have to correct you here, you started out right, a TH350 and TH400 are about the same size, A SHORT SHAFT TH350 and a short shaft TH400 are almost identical in length. I believe the difference is about 3/8". The mount on a short TH400 is 6 3/8" further rearward than a TH350. SOMETIMES you can use the same driveshaft on a TH350 - TH400 swap, I have been able to do it before. sometimes it will not work because of the yoke design. You have to change the yoke anyway, but GM used several different length of yoke on the TH400's. A 200-4R is almost exactly the same length as a TH350 and TH400., It will use a short shaft TH350 yoke and driveshaft, and the crossmember in the TH400 location ~6" rearward. I'm actually installing a 200-4R in the 260Z tonight.

I know they don't eat HP, and this is what I'm trying to explain here. You understand that the hp numbers aren't constant because they would change with the rate of acceleration right? Also the other part that would have to be factored in is the rotating mass in question, doesn't have to accelerate at the same rpm as the engine in 1st gear, most of the weight is out of play in 2nd gear because it isn't rotating, and by the time a vehicle gets into 3rd gear the rate of acceleration has usually slowed because of the lack of gear reduction helping the engine to accelerate as quickly. In a TH400, the direct drum is being driven by the planetaries (reverse rotation) at 84% of engine rpm. On a shift to 2nd gear it comes to a complete stop. On the shift to 3rd it has to spin up to engine rpm from a complete stop. The difference between a TH350 and TH400 direct drum is 2 lbs. A Th400 has heavier planets but they are already in rotation, 2 seperate pieces here, but one is already at engine rpm (and wouldn't require any HP on a shift because it is already in motion, but would use a small amount to continue to accel afte rthe shift), the other must be accelerated, but the weight isn't the total weight of the particular planet, only a portion of it because of the design of a planetary gearset. Sun, pinions, ring. It would get somewhat complicated to calculate because you would have to disassemble a planetary set to get the weight of the ring gear portion.

Dr Hunt, In your profile it states you are an engineer... what type? You should understand exactly what I'm speaking of. It is not as simple as saying it takes X amount of HP, it all depends on how much difference there is and the rate of acceleration. Very similar to figuring HP for a particular car based on the weight, and ET or MPH. IF a car weighs 3000 lbs, and can accelerate to 120 mph in the 1/4 mile, it has X amount of HP. We are figuring the rate of acceleration over a defined distance, by the end result. We know the weight, and we can calculate the HP. If the weight remains the same, but the rate of accelation changes, we know it required a different amount of HP. I'm pretty sure GM never published those specs...They were written in a transmission manual some years ago and I can check but I believe they were approxmations made by a builder at that time.

I never said that there was no difference, just that there are other factors in play that have an effect. A TH350 has a greater friction area overall, if you figured it in 1st gear, where it would be driving through all the frictions except the forwards which are always engaged in any forward gear, and the low/reverse which would be engage in 1st. The direct clutches would be driven through and the surface area is slightly smaller than a TH400, but the intermediates on a TH350 are much bigger and are also driven through. Once it shifts to 2nd, they are on even turf. Once it shifts to third, it depends it the best answer I could give. "I" believe the Th400 would have a bit less frictinal loss due to it using a band, than a Th350 which uses clutches. However it would depend mostly on the band clearance or the clutch clearance. If you set up the clearances looser, you reduce friction. I would recommend a MINIMUM of .008' per friction clearance on the directs of eith unit. I prefer to see about .010-.012. On a TH350 the intermediates need to be a bit loose, because they fairly large in diameter. Having .080" or more clearance on this stack of 3 clutches is perfectly acceptable. I would leave low/reverse on the loose side on a racing TH350. It may cause a harsher reverse engagement, but we aren't too worried about it in a performance application. I have built TH350's for use in a Bonneville Salt Flats racer (240+ mph) and I totally eliminate the low/reverse clutch pack, apply piston and related parts for reduced friction and safety. You can use special steels for less drag and quicker application. Many performance builders have gotten away from using grooved clutches at all. You mention Alto. Alto's frictions do not have any grooves. Smooth red paper based friction elements. I use Alto products extensively.

A TH350 has larger intermediate frictions and steels than a TH400, much greater surface area. The forward and direct clutches are of similar size between the two units. A TH400 uses a low band, a TH350 uses clutches. 5 or 8 clutch pack makes little difference in the amount of drag, why would it be of huge concern in a 'glide in the high drum? The clutches would be applied in high gear anyway, the only drag created would be in 1st gear and this would be more affected by clutch pack clearance than count. I would reduce the clutch count in the reverse clutches before I would in the high drum. You can also do other things to reduce clutch drag.

It takes no more power to "turn" a TH350 than a TH400. Most people relate the slightly heavier internals of a TH400 as consuming more energy just because they are heavier and this is not the case. It DOES take more power to accelerate or decelerate a heavier mass, but not to "turn" it, as in steady rpm. Quick explanation.. At idle not engaged in gear, the only portion of the trans that consumes power is the trans pump, as it is pumping fluid at idle to lube the trans and maintain pressure for gear engagement. A TH350 and TH400 use the same gearset. If trans mainline pressure is setup the same, the pumps would consume pretty much exactly the same HP. Very minimal anyway. Some of the parts that make a TH400 heavier (a total of about 15 lbs heavier) are not rotating, the center support for example in a TH400 is probably 2 lbs of this difference and one of the reasons a TH400 is more durable. It is better at keeping the parts running true and centered in the trans, remember this for later. The direct drum in a Th400 weighs ~14 lbs fully loaded and filled with oil. A Th350 weighs 12.. 2 lbs difference. I would theorize that the direct drum is the most power consuming portion of the transmission during acceleration, particularly in 3rd gear, on a shift from 2nd to 3rd gear the direct drum must go from ZERO rpm to engine rpm pretty much instantaneously. THIS is what consumes power. Accelerating the mass... We're talking about 2 lbs difference on the direct drum...The diameter and weight of the torque converter has a larger effect. Most sportsman racers think nothing of adding a couple of lbs for anti-ballooning plates. The amount of HP used doesn't change if the drum is in steady motion, or constant RPM. If it takes 3HP to operate the pump, and 2 HP to overcome frictional losses, that would be all it takes to operate either transmission at steady RPM. If you accelerate the parts (or decel) then the greater mass would require more HP, but the amount of HP required is dependent on how quickly you accelerate it. A 14 second 1/4 mile car will never accelerate the parts quickly enough to realize any measurable HP difference. A 10 second car MIGHT see .05 seconds difference in ET due to the rotating mass difference of a TH400 An 8 second car might have a noticeable difference in ET, but it also wouldn't likely be using stock weight parts. I can take 1 lb off of a stock TH400 direct drum fairly easily. When someone states that a TH400 require ALOT more HP to "turn", "run", etc. they usually do not even know why they are saying it, just repeating what they have heard. This is also why stating a TH400 takes "15 hp" more to operate than a TH350 is incorrect, there is no set number for this, as it would absolutely depend on how fast the parts where accelerated during testing. I would also venture to guess that a TH400 actually has LESS frictional loss than a TH350...

Please explain to me how a TH350 takes less power to turn... Keep in mind Newton's First Law of Motion...

The governor is just one piece of the puzzle. It is the road speed sensing device that affects shift points, however it does not control the shift points, the valve body controls shift points using input from the TV and governor. A generic valve body with a Grand National calibrated governor will not upshift out of low gear until well over 6500 rpm if ever. The complaint of varying rpm at the shift points betwen certain gears is a valve body issue. Changing the governor will move these points up or down, but not equalize them. If it shifts from 1-2 at 4800 rpm, then 2-3 at 4400 rpm, 3-4th at 4000 rpm, then you would have to increase the tension of the 2-3 shift valve spring to increase the rpm that shift occurs, and the 3-4 shift valve spring to increase that shift rpm. Unfortunately, the governor is not the answer here and while some mods can be done to increase WOT shift points, if you get too aggressive with these mods, the part throttle calibration gets weird requiring ALOT of trial and error valve body work to get it working right. ATF showers...

Another bit of info on the 200-4R. The "good" valve bodies that control shifting are from the performance cars. Buick GN's, Monte Carlo SS's, Hurst Olds, Pontiac TTA. These valve bodies result in better shift points than the generic valve bodies. Some of the generics are better than others. According to Chris at CKperformance the Cadillac AA code VB is a good one to use. The rare performance VB's alone go for $250-400. BRF is the 86-87 GN part. BQ is the 84-85 GN vb. I think a good 200-4R can be built without the pricey VB's but very high rpm auto WOT shifting will be difficult to obtain. Most people manually shift anyway...