Thanks, Jim, once again very informative. I agree that in 90% of driving an automatic will perform as good or better than a manual & no doubt that hi tech one will out perform a manual 100% of the time. Still it takes a higher degree of skill to drive a manual so that may increase the "fun factor" JMHO. That being said I'd never go back to a manual for a daily driver. Did you consider any of the self shifting manuals? Also what you said about using a 200 4r to do what you wanted got me wondering.... Care to share your ideas on that? What you are doing helps the rest of us think outside the box too.
Consider for a moment that before there were synchronizers it was necessary to match gear speeds during a shift. Not terribly hard on the upshift but when downshifting it required a well timed and executed double clutch, something that truly set the skilled driver apart. Fast-forward to today and you never hear of the actual need to double clutch, except perhaps in a heavy truck, yet the skilled driving of a powerfull car is none the less a pleasant experience, and few except a dwindling number of former experts would miss the passing of the unsynchronized gearbox. I don't mean to take anything away from the pleasure of executing a precise and powerful clutch and upshift or downshift, but in the heat of battle, being able to just slam the lever forward or back and get the same result will eventually win out because it is simpler, the same as synchros did. At least that is my prediction. But it's getting the same result that is crucial. Gear slammers won't give up their clutches as long as they have a percieved advantage and rightfully so. There are a number of things the manual box does better, particularly in regards to allowing a gear change without impacting traction when the tire is already at it's extreme limit of adhesion, such as when maxed out in a corner. But there are other things as well. Like declutching to blip the throttle or rev the engine. Might not seem like much but to a manual transmission driver it is indeed a big deal and so far as I know there is presently no automatic transmission on the planet properly equipped to carry out this function. But it only requires software, and maybe a pushbutton switch on the floorboard. To be fair about it, I didn't investigate the auto shifting manual transmissions very extensively. I looked into the BMW system and was not initially very impressed with it and moved on. I'm not sure what my impression would be now but I'm no authority, I'm just one guy building a car the way I want it. Where the 2004r comes up short is in external control of shift firmness. True, you have your cable linkage to the throttle but that has limitations. Getting shift characteristics suitable for normal street use or street/strip for these is not a problem, but for use on a road course or in the mountains the bar is a little higher and shifting delay is intolerable, but at the same time shift firmness must be modulated over a wider range than any other application all the way from full on banging power shifts to so dead mushy soft you can't even feel it. I would challenge any 2004r rebuilder to meet those requirements. Maybe it could be done, in fact I do feel it should be possible to get very close. But with the advent of solenoid controlled valve bodies the road to that goal got quite a bit more clear. When PWM solenoids were substituted in favor of accumulators it became clear that all characteristics of the shift were now controllable externally and the ultimate goal was in reach. At that point I bought in. JB
I agree that a modern auto box can shift faster than a manual as long as the electronics will allow it. In manual mode they can be just as much fun on twisty mountain roads and are alot less tiring after several hours of driving. Can't wait to see the finished car.
Jim, I applaud your free thinking, to go a new direction. This trans your using,"may" have considerable, parasitic losses, vs. a manual or other autos, they tend to vary substantially. Got a figure ? Ever consider CVCT?(always in the right gear). Cheers, roverman.
Art, is there a CVT for RWD, or one that can handle 500 hp+? I'm just not sure the technology is there yet. As for the parasitic losses, I have no idea where to even start with that. Maybe you could post your info on the ones you have figures for, that would give me some idea of the range. I would think that would have been one of the things that the Lexus engineers looked at when they were attempting to build the world's best automatic, with specific instructions to think outside the box, but who knows? Certainly not me. But one thing I do know is that you can think a project to death, literally. At some point it's time to cut metal. And once that starts it's usually best not to look back. JB
I am sure you are going to have no major loss from that trans compared to other options... I have heard that the loss amount for a given trans is more of a constant and not a percentage of power made... So maybe you will lose 30 hp however if you make 500 hp then it is no big deal. I also think that the gearing in that trans is AMAZING!!! Any possible increase in power loss would be a wash compared to the improved gearing. I really like this project! It is nice to see someone with your abilities and tooling going all out with a SBB....
Jim, I think you mean inline rear drive ? ZF had their lates/greatest, production unit available as an option in Ford 500's, several years ago. Never seemed to catch-on. They never quoted parasitic losses. Hot Rot, Pop Hot Rodding, etc., have had articles comparing losses of Amer. rear drive autos. One was reportedly the 727 Mopar torqueflite, consuming 76 more hp. than Chev. powerglide.
Well, the venerable old 727 Torqueflite which was a contemporary of GM's powerhouse THM-400 was used in everything imaginable, from nearly every Chrysler product ever made in those years up to and including International Scouts, dragsters, motorhomes and busses. Had a real long production run too, starting back in what, the late sixties? Used a lot of sleeve bearings and such, but the biggest loss had to be from the torque converter. Modern designs all use a lock up converter so you can cut the losses at least in half right there. As for why the powerglide should be 76 hp less, I can't say but something there doesn't sound quite right to me. Both used the same sort of design all the way through with just a few less components in the powerglide. Personally, I've owned, driven, and been inside both of them and I just don't buy it. That much of a difference would have been too obvious to have gone unnoticed. For instance, the Plymouths and Dodges of the day were competitive with the Chevys, Pontiacs, Olds, and, ... dare I even say, Buicks? So there could not have been that much difference between the 727 and the TH400, and I swapped out a powerglide for a 400 and would certainly have noticed an extra 75 hp of drag when that happened as it would have turned the car into a dog that even the extra gear couldn't cover up. It didn't and in fact ran much better. So I'd say that test was faulty. Hogwash in fact. The Ford 500 had a little over 200 hp output and torque about the same. What I do want is a transmission that will handle well over the torque my engine produces and considering the torque rating of the stock 340-4, something in the near 500 range would only be prudent. As far as I'm concerned, the jury is still out on RWD CVT units. I have yet to see one, and I'd have to see the innards before using one in a project car. Considering the design principle is to use a belt and variable diameter pulleys similar to the drive head of a Bridgeport mill, I fail to see how that can be packaged to fit the transmission tunnel in a RWD application. Transverse, sure. But North/south will be a problem. (Ford 500 is a FWD+ application so the configuration of the back half of the package is a very real question) Maybe if you built the car around it you can do it but that's not going to work very well for a retrofit. The power capacity of this type CVT is directly related to physical size, so upgrading one to handle more power is really not an option either, and one big enough to handle 500 hp (if you could find it) is not going to fit in an MGB body unless I've really missed something significant here. But again, the bottom line is that the choice has been made, parts are in hand, and the design is moving forward. The tranny adapter is complete except for three holes and paint (photos soon, maybe tomorrow) and I see little advantage at this point in spending any significant amount of time looking for new options. That can wait for the next build, assuming that happens. For now I need to concentrate on the British V8 meet in 2-1/2 weeks and try to get the engine in the car. JB
Yesterday was the day for bolting the engine and tranny together and setting them in the engine bay. Assembly went smoothly without a hitch, but unfortunately fitting the engine in did not. The stock 340 motor mounts will not work, no surprise there as they are considerably larger than their 215 counterparts, and the steering shaft and heater box all cleared, but I had to cut a fixturing lug off the block just like we did on the 455. The motor sat too high so I unbolted the steering rack. It will have to be moved down just like in the MGB-Roadmaster, although I believe moving the firewall cone can be avoided, and I'll have to make up a set of front engine mounts like what we used there. So the good news is that there is progress, the bad is that the car will not be coming to the British V8 show this year. There is just too much to get done in time to even be able to trailer it. Motor mounts, transmission crossmember, rack mounts, crossmember notch, rack pinion extension, new rack boots, and waiting on parts. Well, those are the breaks sometimes. There's a shot of the setup I used for dialing in the adapter ring to mark the bellhousing holes, and here is a shot of the completed adapter including the converter disc, which was cut from 1/2" plate and has helicoils for the flex plate bolts. The next shot is of the engine and 8 speed automatic assembled and ready to go in the car, and then a couple of it sitting in the engine bay. JB<script type="text/javascript"> //<![CDATA[ var iba_elt; iba_elt = document.getElementById("in_body_attachment_5813"); if (iba_elt) iba_elt.onload = function() { if (window.in_body_attachments_resizeimage) in_body_attachments_resizeimage(this); } iba_elt = document.getElementById("in_body_attachment_5814"); if (iba_elt) iba_elt.onload = function() { if (window.in_body_attachments_resizeimage) in_body_attachments_resizeimage(this); } iba_elt = document.getElementById("in_body_attachment_5815"); if (iba_elt) iba_elt.onload = function() { if (window.in_body_attachments_resizeimage) in_body_attachments_resizeimage(this); } iba_elt = document.getElementById("in_body_attachment_5823"); if (iba_elt) iba_elt.onload = function() { if (window.in_body_attachments_resizeimage) in_body_attachments_resizeimage(this); } //]]> </script>
Any progress on new motor mounts... i wanna see a vid of this running with the 8speed auto lol btw/ how much hp and torque are you pushing?
Motor mounts are done, made from 10 ga stainless. Tubed and plated the frame rails, tranny mount comes next and then steering rack. I figger it'll go at least 300 hp... JB
>Jim, you"figger"? Sounds like a mighty big sandbag! At the rear wheels,extra big disk brakes-full on ? I figger, if it runs like it looks, your gonna need duals, on the back, lol. roverman.ou:
bump! I "figger" you'll be at 400hp easily lol i'm really curious on much much hp/torque that 8 speed can take as i doubt anyone makes billet/hard parts for it
Let me see what I can dig up... The stall torque ratio is 1.83:1 so the effective off the line ratio is 8.41:1 then with a 3.45 axle ratio that comes to 29:1 overall. Yep, paddle shifters would be handy, that's Low Range territory. Now I see why they use the lock up clutch in the top 7 gears. Top gear is 2.36 overall so rpm at 70 will be about 2100. (Making road speed at 6 grand highly illegal.) If I'd known I was going to use this transmission I might have used the 2.88 gears, but I'm guessing it's going to be quite a blast to putt about in. Maybe I should start collecting parts to build that other hogs head. It's described as a "high capacity transmission", whatever that means. Factory cars have been produced with 425 hp and about 375 ft lbs. Well, I might be a smidgen over that torque figure, going from factory specs and bumping it up just a little. This resulted in a 12 second quarter in a 3825 lb car. Mine will be about 2500, maybe a bit less when finished so if I can avoid too much wheel spin maybe I can make that 12 second run some day. JB Edit: Oh, also it has two planetary sets. One of them is a compound planetary with two different sized planets.
8 speeds sound soo intriguing coupled with fuel injection and turbos :-D only bad thing is I think i may have to regear as i only have 3.08s...and sadly the torque from the turbos may kill it...but i'm sure it has to take a decent amount more then what stock vehicles put out! so it's still possible to hold up to 500 hp or so
supposivly there was a twinturbo 2UR-GSE(lexus IS-F) at sema in 08 that putout 600hp.. not sure if they beefed anything up or just slapped on the turbos
The only listed transmission mod was Amsoil transmission fluid. "What I learned from my first Lexus build is the quality of the engine and driveline from the factory," Brian explains, "I now have 13,800 miles on this motor and it's still stock (other than the twin-turbo). I beat the living crap out of the car and added over 200hp to it! If I did that to an M3 or something with a stock motor, it would blow sky high. This just shows how over-engineered the IS-F is and that it's worth every dollar!" (625 HP) JB
i guess myy 3.08 with 28in tires will practicaly match the factory lexus ratio of 2.937 (my effective ratio will be something like 2.94) I'm starting to feel confident that this transmission will hold up well to my combo to come! so, if i find an aa80e locally i may have to pay you to make me a bellhousing adapter :-D
