Guest jwelch Posted March 10, 2002 Share Posted March 10, 2002 I have a question about my 700R4 tranny. My tranny seems to be locked up in all gears. I failed emissions today because they said I had no rear brakes. The tranny is locked up at idle and the front brakes are the only thing that will stop the car. On the dyno the rear wheels still turn because the tranny is engaged Any solutions? Thanks John 77280Z 69 383 Charger Quote Link to comment Share on other sites More sharing options...
383 240z Posted March 10, 2002 Share Posted March 10, 2002 What do you mean locked up? is the converter clutch on or is the geartrain locked together? how does it drive do you have any forward gears? reverse? I can help you but need more info. Keith Quote Link to comment Share on other sites More sharing options...
Guest jwelch Posted March 10, 2002 Share Posted March 10, 2002 Hi Keith, I think I used the wrong words to describe what is happening. All gears are working, forward and reverse. 1) The car's rear wheels are always pushing even when I'm at a stop light but still in drive. The idle is set at about 800RPM and rear wheels are still trying to turn. When I had it one the dyno at emissions the rear wheels would not stop when I put the brakes on with the car in drive. They were still turning very slow and you could feel the push or torque it still had. "Maybe the clutch is engaged?" 2)When I "stomp" on the gas the car takes off but will not spin the wheels even at 4000RPM. I should be able to smoke the tires easily. 3)The tranny is still shifting into all gears including 4th (no problems shifting) This tranny is about a year old and has been completely rebuilt. No stall convertor (or at least stock). I have changed the intake and gone to Holley Projection on it, so I know the TV cable is not set as it was before. I used the paperwork that I have to set it the best I could. Maybe I have the cable set wrong? Any thoughts? Thanks for your reply John 77 280V8 69 383 Charger Quote Link to comment Share on other sites More sharing options...
Modern Motorsports Ltd Posted March 10, 2002 Share Posted March 10, 2002 Jwelch, have you altered or refreshed your brake system at all? You should have enough rear brake pressure/friction to hold your brakes/rear tires at an idle with motor still in drive. If you've altered your brake setup, you need more rear line pressure. Lowering your idle and backing off on timing will reduce your torque at idle greatly.......when I first setup my 280ZXV8 a number of years ago, it would literally 'squeal' the treads as it torqued them into the concrete when I put in drive on a cold idle in a parkade with very smooth pavement to leave each morning........barking at idle is cool but looses it's novelty after a bit... Quote Link to comment Share on other sites More sharing options...
Guest jwelch Posted March 11, 2002 Share Posted March 11, 2002 Hi Keith, I will have to ask the shop on specifics, but I know there was a light shift kit installed. What would be an easy way to find the leak? Also I'm not using the lock up brake switch that I've heard alot about. The tranny used to run very well although I've never really been able to do the smokey burnouts like I've seen so many Z8 cars do. Ross you have a good point on the brakes. I did change the booster and master cylinder but the brakes seem to work better than before. I couldn't stop the car at an intersection before the tranny would just push me right out in the middle of the intersection. How do I get more pressure to the rear lines (proportioning valve adjustment?) I have the idle at 800RPM but the timing has a lot of advance. I can try to adjust this but then I have to fight to get through emissions. Also a good point on the TV cable adjustment was made. The problem is that bowtie overdrives hasn't completed a system that fits the holley pro-jection yet. They said it is process and could take a month or so. Thanks John 77 280V8Z 66 383 Charger Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted March 11, 2002 Share Posted March 11, 2002 Sounds like your lock-up is shorted out. Typically, this is caused by the pan or filter being up against the 4th pressure switch. Anyway, I would check this first. Bry Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted March 11, 2002 Share Posted March 11, 2002 Sorry, should of added this last time. Just uplug your transmission (electric plug on the side), and see if you still have the problem. This will isolate the problem. Bry Quote Link to comment Share on other sites More sharing options...
Guest jwelch Posted March 11, 2002 Share Posted March 11, 2002 Bry, I will try this and see what happens. Last time I was under the car I don't remember seeing the eletronic plug. Is it on the passenger side of the tranny? Do you think I should run the lock up switch that attaches to the brake switch? Thanks John 77 280V8Z 66 383 Charger Quote Link to comment Share on other sites More sharing options...
383 240z Posted March 11, 2002 Share Posted March 11, 2002 did it work ever? It sounds as though you may have a small leak internal that is applying the low clutch pack but no smoke for a full foot acell? what mods were done to the tranny when it was rebuilt is there a shift kit installed? if so what type and stage? I'll be able to give you a better answer tomorrow. Keith Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted March 11, 2002 Share Posted March 11, 2002 A recent article was profiled in Chevy High Performance to connect a tv cable to a carburatored GM 700R4 or 2004R transmissions by BOWTIE OVERDRIVES. I am definitely going to use this tv attachment on my project with Edelbrock carb to 2004R. This may not be the problem you have but is definitely an easy way to get an accurate TV adjustment. Quote Link to comment Share on other sites More sharing options...
Andrew Bayley Posted March 11, 2002 Share Posted March 11, 2002 John, I wouldn't spend too much time looking at the lockup converter. If the converter was actually staying locked up, the engine would stall every time you came to a stop (much like leaving a manual transmission in gear and coming to a stop). From my experiences with 700R4's, it's sounds like a combination of a stock converter and high line pressure. A lot of shops will adjust the line pressure higher than it needs to be, simply to give the driver a "shift kit" type of feel. To see if you have this problem, simply disconnect the TV cable from the carb, start the car up, put car in gear and see if she still surges ahead with as much force as before. Do not drive the car around like this!!! The TV cable is what adjusts the hydraulic fluid pressure for all the bands inside the transmission. With the TV cable disconnected, the minimal amount of pressure will be applied to the bands. If the car is driven with this minimal amount of pressure, the bands and clutches will most definitely burn up. The proper TV cable adjustment should be a zero tension while the motor is at idle. As soon as the throttle is increased, so should the TV cable. At WOT, the TV cable should be at maximum pressure (fully opened). Every like’s to pretend that there is some great voodoo mystery with adjusting these transmissions. It's actually quite simple. Keep us informed. -Andy Quote Link to comment Share on other sites More sharing options...
Guest jwelch Posted March 11, 2002 Share Posted March 11, 2002 Hi Andrew, Thanks for the reply I will try this too. If this happens to be the issue, is it an easy fix? Thanks John 77 280V8Z 66 383 Charger Quote Link to comment Share on other sites More sharing options...
Guest jwelch Posted March 12, 2002 Share Posted March 12, 2002 700R4 Update: Got home from work and started trying some of the tips everyone has recommended. Thanks for all the help. I still have a problem with the car surging with it in drive and foot pressed hard on the brake pedal. The car jerks with every lope of the engine. If I set the idle low enough the car will actually die when I put it in gear. I have to set it at about 700RPM to make it die when I put it into drive. I tried removing the TV cable from the trottle body and no difference. I also unplugged the lock up switch and no difference. Starting to worry if I have something seriously wrong? The tranny has very low miles after the rebuild, the shop I used had to put a new valve body in this tranny about a week after I got it back (warped valve body). The syptoms aren't the same but I believe someone did mention it could be an internal leak? Could the TV Cable have some "pre-tension" already set up inside even when the cable is un-hooked from the Throttle body? I do agree that the brakes may be part of the problem but I don't understand the WOT burnouts. I saw Andrews pics at the track.WOW I can barely get the tires to chirp. Something is definitely wrong. I'm open for any ideas. Thanks in advance. John 77 280V8Z 66 383 Charger Quote Link to comment Share on other sites More sharing options...
Guest needwaymorespeed Posted March 12, 2002 Share Posted March 12, 2002 It sounds like the torque converter the converter should allow the engine to idle .the converte is a viscous coupling no -fixed coupling unless the lockup is engaged-basically applies a friction disk like a standard car when the lockup is on- Since the car does not die when put in gear with the engine at normal idle-I think the lockup clutch is ok-with a bad lockup clutch,stuck on or welded the car will die when put in gear at idle just like a standard car is you drop the clutch in 1sr gear at idle ,but youre car runs at normal ifdle speed so I would then suspect the stator inside the torque converter especially since you mentioned the car was sluggish- good luck Quote Link to comment Share on other sites More sharing options...
Andrew Bayley Posted March 12, 2002 Share Posted March 12, 2002 Every bit as easy as adjusting your throttle cable. E-mail me if you need to know the specifics: abayley@lear.com -Andy Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted March 12, 2002 Share Posted March 12, 2002 Thanks Mr. Andrew, You may have saved me around $100.00 dispelling the myths about voodoo 700R4 TV cable interference from outer space zombies. I will definitely refer to your instructions when installing the 2004R with Camaro shifter linkage.I got about a few thousand dollars worth of advice so far. Quote Link to comment Share on other sites More sharing options...
Andrew Bayley Posted March 12, 2002 Share Posted March 12, 2002 John, Thanks for the kind words. This big smokey burnout of mine was done in the water box with the help of a line lock. The "two stage" burnout photos were done on dry pavement. Even with my 3000 RPM stall converter, some skill (if you can call it that) is required to light up the rears. I need to "stab" the throttle in order to break the wheels loose... even with the line lock on. If I gradually lay into the gas, the motor will push the (locked) front wheels like skis on a sled. If I had the OEM converter in my transmission still, I doubt that I would be able to break the tires loose on dry pavement at all. The stock converter in my '87 (Z28 Camaro) 700R4 was junk! Stall speed was something pathetic like 1400 RPM. I too, would plow the front wheels around unless I was hard into the brakes. In a heavier Camaro, this problem isn't as pronounced as it is in a lighter Z. Especially since our V8's typically have more torque than what a stock Camaro ever came with. Swapping to a high stall converter was the best investment I ever made. With the exception of my Nitrous kit, the 3000 RPM converter was the quickest modification I made to the car. I dropped over half a second off my 1/4 mile ET. Now for the bad news, lock up converters for 700R4/2004R's are not cheap. Expect to spend around $500, maybe more. The non-lockups are "slightly" less expensive, but not worth it IMHO. Spend the extra amount and get a lock up. Also, when looking for a suitable stall speed, go with slightly more than what you think you'll need. A few reasons for this. First, the light Z will stall less than what the manufacturer claims. My advertised 3000 RPM stall is actually between 2800 and 2900 in the Z. Next reason, you will more than likely want to eventually go faster. A torque converter is not something you want to swap out more than once. Finally, people underestimate how much “stall” they will be happy with. Remember, just because the converter is rated at, say 3000 RPM, this does not mean it won’t do anything until it reaches this stall speed. The stall speed is simply the maximum RPM that the converter will slip at. If one end of the converter is solidly attached to something, a mating engine would only be able to reach 3000 RPM at WOT (until the impeller vanes burn out, then all hell breaks loose). Taking off from stop lights will still be like an OEM converter, only it will fell “slightly” looser. This is the best part. With just a touch of gas, the motor flashes up to about 2100 RPM and I’m gone. I don’t know how many people thought I was racing them while I was just “puts-ing” away from a light. They would eventually learn. Get a high stall, you will not regret it! -Andy Quote Link to comment Share on other sites More sharing options...
383 240z Posted March 13, 2002 Share Posted March 13, 2002 After thinking some more about your issue and it sounds like a converter problem you dont have enough stall. The only way to fix this is get out the checkbook. Keith Quote Link to comment Share on other sites More sharing options...
Guest jwelch Posted March 13, 2002 Share Posted March 13, 2002 Thanks again for the help. Any recommendations on a brand of torque convertors and who would have the best price? Andy, I'm wondering if 3000 RPM is too much for my engine. I have approx. 340BHP at best. Another concern is breaking the input shaft on the 700R4. I saw a dyno graph on bowtie overdrive's site and it showed the input shaft breaking at 365lb of torque. Have you had to upgrade your tranny to more robust parts? Thanks John 77 280V8 66 383 Charger Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.