Kevin97ss

Just finished up a t56 to 200-r4 conversion. Still on jack stands I put it in reverse with my foot on the brake and it shut right off. Restarted and tried again this time from neutral to 1st and again it shut off. Tried again this time without my foot on the brake and it kept idling but could not stop the wheels from turning standing on the brake. This is a non-lock up converter, spragless 32-3400 stall, 2.0str. I'm thinking this converter is just wrong but maybe its a tune issue...still using my t56 tune updated for the 40 tooth reluctor and 4l60e speed sensor. Anybody deal with this before?

hrcslam

I wouldn't imagine a tune would cause the symptoms you describe. Sounds like your torque converter is a lock up and it's stuck on. And your brakes should've easily stopped your tires from spinning against an idling engine, or stalled it out.

Maybe you have a vacuum leak? Brakes have no power and stalling in gear could be an AFR issue caused by a vacuum leak. You have a data log?

Why a 200r4? why not a 700r4? And what car is this in? 1994 and newer F-Bodies took 4L60e's....

Kevin97ss

No vacuum leaks, engine ran and drove perfect with the t56. The swap is in the 97 in my sig. Wanted it for a few reasons which are debatable, but to name a few: weight, gear ratios, full manual reverse valve body. Anyway was thinking the IAC cannot anticipate the car going into gear so the tune may need to compensate for that...IDK, carb cars did not have this issue. Seems like it has a stall speed ~1000 rpm or you could be right and it has a lock up clutch, but... I did find it I get it into 3rd gear the brakes will stop the wheels from turning and it will idle. Never seen anything like it.

hrcslam

That is very strange. I'm thinking the trans is messed up then. But, what's throwing it off is that the brakes don't work in 1st. Your brakes should over power your engine if you stand on the brakes, especially at idle and you should even need to stand on the brakes.

Kevin97ss

Its not that the brakes don't work, they are working but cannot hold the wheels from turning in reverse, first and second gear. If I stand on the pedal the wheels will slow and the rpm drops like its going to stall, then the IAC opens up and the wheels keep pulling through the brakes. It behaves just like a clutch unless its in third or fourth gear. Idle speed is around 825-850 rpm. I figured a converter with a stall above 3k should be barely noticeable when put in gear.

mobileman

iTrader: (7)

I have had a few of these cars through the years and all mine did this. When I saw it on the first one on the lift I changed a few parts till I decided to try it on another one of my cars and it did the same thing.

hrcslam

Kevin97SS, the brakes on our cars are weird for sure. But, I don't see how the IAC can idle the car up so much that the power brakes couldn't stop it.

Maybe on the ground it's a different story because the weight of the car and the front brakes are working against the engine too. That actually makes sense now. LOL.

mobileman, how did you fix it?

Kevin97ss

Just got off the phone with my converter guy and he knew off the bat there was a mistake and I got some ones lock up converter but it still had him stumped as to why it would idle in 3&4th gears.

hrcslam

Actual RWTQ changes in 3rd and 4th. In first the engine torque is multiplied by 2.74, assuming 200ft/lbs you'd be looking at 548 coming out of the trans, then that's multiplied again by the rear drive ratio. In 3rd it's 200 out of the trans, and in 4th 134. It's easier for the brakes to over come the tq.

The thing is though, you should've dropped back to first automatically. This whole thing is weird honestly. Hopefully the new tq converter fixes the issue. Let us know.

Also, why no lock up? Does the 200r4 not come with lock up? And if it does then why not use it?

Kevin97ss

Its a manual reverse valve body...no automatic features. The 200-4r is a lock up capable trans but for how I use the car I don't want to carry the extra weight in the converter.

hrcslam

Ahh tracking. I'd give it to tq multiplication in lower gears vs the frictional power of the rear brakes. What's weird though is that the engine didn't stall in those gears.

Kevin97ss

Yeah, if I had to guess it was slipping the clutch because it was new and not yet burnished in. Sucks I got to tear it apart again...glad its just a toy!

mobileman

iTrader: (7)

There was nothing to fix the brakes on these cars will not stop and hold the rear tires when the car is in the air. I have have tried it on a few but they seem to work fine going down the road. I dont know if the car releases them because it sees the front not rolling. Ive seen it on at least four cars.

Kevin97ss

Most likely what you have witnessed is the ABS system dumping pressure from the rear brakes. This car has the ABS system deleted with an adjustable proportioning valve.