hi i live up in the mountains in north wales UK i am happy with the th350 (behind my 350 71 skylark) up and down hills but i could do with overdrive when i travel long distance (600-800mls) on the motorway (highway ?) at 70-80mph will a 200r4 trans be happy dragging up and down the hills never really getting into top gear untill i get on the open road and will i need new trans lines or will the stainless th350 lines i have on my car work without to much stress also i take it i will need the 2004r filler and some new way of locking the torque convertor as i see people mentioning kits to do this ? is the no way of using the stock set up ? if not why not ..... lots of questions but no one here in the UK has much experience with 200r4 transmissions and the only person i have met who knew what a 71 skylark was happened to own the only other one i have seen !
i would rather have some advise, i find phoning a shop that is 8hrs out of sinc with the UK interesting and mostly there advice is buy everything from them and then pay massive import duty and that is not a option
I think the TH-2004R would be fine in your application but it was expensive enough to do here let alone doing the shipping and duties game to get the stuff over there... If you are running anything numerically lower than 3.42 in your differential an d you want to utilize the lockup converter you will most likely want to plan on upgrading that as well.
upgrading the convertor ? is it likely to overheat or break ? i was thinking the point of a overdrive was to have taller gearing in third gear the 200r4 would be running the same gearing as my stock th350 1-1 it is on long drives at speed i would like to be able to drop the revs and increase my mpg i think it is nuts my car is rated at 230hp and has the same top speed as my wife's little french 65bhp hatchback !
For your purpose I think nearly any quality converter will be sufficient. You will want to add an additional external cooler though and don't cheap out! As for the overdrive don't get into the assumption that you can gear the car where it will theoretically do 70MPH at 1500RPM. You will just put a lot of stress on parts and end up with a car that is no fun to drive. IMHO Larrys suggestion of the Gear Vendors system might be a great way for you to do what you want with solid reliability and possibly less overall work. Do some searching on here and via Google regarding the installation of the TH2004R and the gear vendors system and READ about the challenges and results. Most info you find regarding the 2004R will be here and on the corvette forums. The GV stuff will be spread all over. The 700R4 gets most of the attention in the chevelle board and while the silly low 1st gear is not ideal for racing it might make your combo more fun as it will jump off the line a lot better or spin the tires if you are so inclined and Give you the OD you desire. You can probably find someone over there than can actually rebuild a 700R4 as they are pretty much the same critter as a modern 4L60 that GM uses in millions of trucks world wide. A 4L80E is another possibility but probably the least desirable as it's heavy, and expensive especially when you are not likely to be able to scrounge a core to build yourself in the UK. Regarding your question about lines I think the TH350 lines can be tweaked to work with the 2004R but will likely need cut or replaced for a 700R4. And lastly all the overdrive options discussed above are effectively a 4th gear (the GV unit can be a bit more flexible). All options are plenty robust for a 350cid with maybe a few internal upgrades on the 200/700.
That is the beauty of the Gear Vendors Overdrive. You can turn it on and off in any gear. It was originally used in motor homes, so it is very stout, you won't break it. The 2004R was a light duty transmission from the get go. It can be built to withstand much higher torque and horsepower, but at added cost. You can't use your 350 torque converter, so you are looking at buying a new converter also. In addition, the 2004R uses a TV cable to control the transmission, so you will need to adapt your throttle lever to hook it up. The GV bolts onto the back of your current transmission. You need to shorten your drive shaft. It gives you a .78 OD gear. To me, that is a much simpler solution for what you want to do. Both options are likely to cost you the same, but you may in fact be able to find a GV unit used in the UK, have you looked? If not, I think it is worth it to do so. That 230 HP is gross HP. Your wife's little french car is likely net HP. I would think there is quite a weight difference also. Are you really surprised the top speeds are similar? That isn't the real motivation for wanting an OD gear?:grin:
thank you guys for the insight i suppose the buick weighs in at 3-4 times the wifes car and the 0-60 time in her car is measured in months ! my point was more that her car is geared to just about pull max rpm in top gear while in the skylark if you are brave (or stupid) you can have the engine revving well into the red while going up a steep hill ....the car just feels like it needs another gear, also i was lucky enough to have a 200r4 with torque convertor more or less given to me (i had to do some work on a vette c3 to get it) the trans i was given is supposed to be one that was reconditioned a couple of years ago the oil is clean smells ok and the paint is clean on the torque convertor so i am thinking it might be a good idea i just need to work out what bits i will need , also my th350 is miss behaving it stalls in drive not reverse and the only way i can drive it is start the car leave it in reverse for 30 seconds then put it in drive and it will behave for 10=15 seconds then bang it is off ! no slipping the longer i drive it the better it gets but even after 1hr if i pull up and hold the car in gear it is fine for 30-40 seconds then bang it is like dumping the clutch on a manual if i drive off before it locks in it is fine
I had a 72 Skylark with that gearing. I could take 1st gear all the way to 50 MPH before it shifted into 2nd. Maybe I am not understanding you correctly, but you said " you can have the engine revving well into the red while going up a steep hill ." I don't get that. In top gear, the 2.56 rear gear gives you 30 MPH/1000 RPM. A 2004R coupled to a 2.56 rear gear would make 4th gear OD practically unusable.
It sounds to me like you have a torque converter problem. Namely, a stator failure. I would put another torque converter in it. That may solve your problem entirely.
Torque converter, or the transmission is slipping badly. 60 MPH should be about 2000 RPM. 336/tire height X rear gear X MPH =RPM ................................. 336/27 X 2.56 X 60 = 1911 RPM with no converter slip. Add in 150 RPM slip and you are at 2061 RPM.
Sounds like it's either not going into 3rd gear or the trans is toast and slipping horrendously. With 2.56 gears you shouldn't need an over drive, at all.
ok next dumb question are all th350 torque convertors the same (i know different stall speeds) but would one from a vette fit ?
Yes, THM350 and THM400 torque converters will fit. There are 2 different bolt patterns as far as bolting up to the flexplate, but stock larger converters should all bolt right up. Stall speeds should be close also. Most stock converters stall in the range of 1400-1600.
All you really need to do is pull the trans and have it rebuilt and a new torque converter. I am sure that you can find a transmission shop that can do it. The TH350 is one of the simplest trans to rebuild. For a little better performance you can have a shift kit put in and get a more performance oriented converter. If you are a decent mechanic you can get a book on the trans and do it yourself.
