Yank Converter - Should I Replace It?
10-18-2005, 01:25 PM
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Yank Converter - Should I Replace It? I have a 2004 Corvette Coupe with an A4 in it.
I am thinking about replacing my converter…. again. It’s expensive, $995 for a converter plus labor to install. I am sitting on the fence so here’s the story, what do you think I should do?
I drag race my car and have tried every type of tire setup there is for a Vette. See my sig for numbers. I am now running a CCW drag pack, that's a set of MT 26-11.5-16 ET Streets. My best 60’ with them is 1.75, not real good for my power levels. In the past I have seen as good as a 1.66 sixty foot and 11.54 with DR’s. But that was before I had my converter opened and cleaned out, twice. Cutting open the converter 2 times might be the cause of my poor 60’ times.
Last spring I bought a Yank PY3600 converter, this is the Nitrous/Blower model with 6 mounting lugs. Running the stock 4L60-e I took it to the track. I was running a set of 275/40/17 MT drag radials at the time. My 60’s were 1.66 and 1.70 with the DA around 1000. On the way home the stock a4 gave it up. I had the 4L60-e built out by Rodney and sent the converter back to Yank. Per my instructions, they cut it open for cleaning. That is the first time the converter was opened.
We put it back together and a month later the 4L60-e blew out again. Once again Yank cut the converter open and cleaned it, that’s the second time. When they did the work Yank advised me that cutting it open causes it to lose efficiency each time it’s done. They don’t like to do it unless they just have to. I didn't believe it was smart to put a contaminated converter back in the car so I had it opened and cleaned again just to be safe. Now I think this process may have ruined it. Here’s why.
The temperature has finally dropped so that I can go to the track and get a fair comparison to my best times last spring. My time last spring was with the stock 4L60-e but now I have a performance built transmission so I expected better times. It didn’t turn out that way.
I went to the track two weeks ago on a Friday night. Among my runs are 3 back to back passes. Each one turned in a 60’ time of 1.75 with the DA at 1280. My tire pressure is 11 lbs. I also let a friend drive the car for two passes so I could watch the tires. There is no slip and the consistent 60’ times seem to confirm this. Last spring I got 1.66 sixty foot times on DR’s. Now I can’t do any better than 1.75 on CCW’s and ET Streets. It may well be the converter. I don't think the problem is a loss of power compared to last spring. Just before going to the track this time I had to get the throttle body changed to an LS2 type, but that's a change from 90mm to another 90mm TB. A dyno run showed 436 RWHP and 395 RWTQ which is very close to my original dyno numbers. (again see the sig.)
Another consideration is that I want to add a 100 or 150 shot of Nitrous. So the bottom line is; should I replace the converter?
__________________
I am thinking about replacing my converter…. again. It’s expensive, $995 for a converter plus labor to install. I am sitting on the fence so here’s the story, what do you think I should do?
I drag race my car and have tried every type of tire setup there is for a Vette. See my sig for numbers. I am now running a CCW drag pack, that's a set of MT 26-11.5-16 ET Streets. My best 60’ with them is 1.75, not real good for my power levels. In the past I have seen as good as a 1.66 sixty foot and 11.54 with DR’s. But that was before I had my converter opened and cleaned out, twice. Cutting open the converter 2 times might be the cause of my poor 60’ times.
Last spring I bought a Yank PY3600 converter, this is the Nitrous/Blower model with 6 mounting lugs. Running the stock 4L60-e I took it to the track. I was running a set of 275/40/17 MT drag radials at the time. My 60’s were 1.66 and 1.70 with the DA around 1000. On the way home the stock a4 gave it up. I had the 4L60-e built out by Rodney and sent the converter back to Yank. Per my instructions, they cut it open for cleaning. That is the first time the converter was opened.
We put it back together and a month later the 4L60-e blew out again. Once again Yank cut the converter open and cleaned it, that’s the second time. When they did the work Yank advised me that cutting it open causes it to lose efficiency each time it’s done. They don’t like to do it unless they just have to. I didn't believe it was smart to put a contaminated converter back in the car so I had it opened and cleaned again just to be safe. Now I think this process may have ruined it. Here’s why.
The temperature has finally dropped so that I can go to the track and get a fair comparison to my best times last spring. My time last spring was with the stock 4L60-e but now I have a performance built transmission so I expected better times. It didn’t turn out that way.
I went to the track two weeks ago on a Friday night. Among my runs are 3 back to back passes. Each one turned in a 60’ time of 1.75 with the DA at 1280. My tire pressure is 11 lbs. I also let a friend drive the car for two passes so I could watch the tires. There is no slip and the consistent 60’ times seem to confirm this. Last spring I got 1.66 sixty foot times on DR’s. Now I can’t do any better than 1.75 on CCW’s and ET Streets. It may well be the converter. I don't think the problem is a loss of power compared to last spring. Just before going to the track this time I had to get the throttle body changed to an LS2 type, but that's a change from 90mm to another 90mm TB. A dyno run showed 436 RWHP and 395 RWTQ which is very close to my original dyno numbers. (again see the sig.)
Another consideration is that I want to add a 100 or 150 shot of Nitrous. So the bottom line is; should I replace the converter?
__________________
10-18-2005, 02:57 PM
#2
Cutting the converter will not change anything about the performance, or the way it will act!
the converter can be rebuilt at set number of times, the same is true to restalling it, after that you lose the weld area.
if your times have changed look at mods done at the same time of about the time as the converter was rebuilt
I have rebuilt our motorsport converters many times and have dynoed them. In testing a converter that has been rebuilt, and the results always come up the same as when the converter was new.
the converter can be rebuilt at set number of times, the same is true to restalling it, after that you lose the weld area.
if your times have changed look at mods done at the same time of about the time as the converter was rebuilt
I have rebuilt our motorsport converters many times and have dynoed them. In testing a converter that has been rebuilt, and the results always come up the same as when the converter was new.
10-18-2005, 03:33 PM
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Originally Posted by Yank
Cutting the converter will not change anything about the performance, or the way it will act!
the converter can be rebuilt at set number of times, the same is true to restalling it, after that you lose the weld area.
if your times have changed look at mods done at the same time of about the time as the converter was rebuilt
I have rebuilt our motorsport converters many times and have dynoed them. In testing a converter that has been rebuilt, and the results always come up the same as when the converter was new.
the converter can be rebuilt at set number of times, the same is true to restalling it, after that you lose the weld area.
if your times have changed look at mods done at the same time of about the time as the converter was rebuilt
I have rebuilt our motorsport converters many times and have dynoed them. In testing a converter that has been rebuilt, and the results always come up the same as when the converter was new.
Now please understand, I am not hammering on Yank or Dave Myers. Dave was very helpful and in no way am I complaining about anything he or the company has done for me. I am just trying to find the source of my performance fall off.
As I indicated the shop did a dyno tune after the new TB was installed and the numbers are within 6 points of where they were last spring. The only modification made other than that was the A4 rebuild.
Running 16” ET Streets should be getting me into the 1.5x sixty foot area. At the very least I should be able to get back my 1.66 performance I had before. I base this on the past performance of the car and the dyno numbers. I know that dyno numbers are not the be all, end all. But the dyno numbers do give me a reliable baseline for comparison, same car, same dyno, same shop, and same mods.
The ET Streets hook much better than the DR's did. In large part this is because the pressure can be dropped lower than the DR’s and I can get some sidewall flex. In addition I know of other cars in my area with power levels less than mine getting such numbers.
It just doesn't make any sense that with the ET Streets I am going 1/10th slower on my 60's. I just don't know where else to look. Since Dave warned me about the possibility of an efficiency loss in the converter I am wondering if this could be the problem. Even the SOP meter tells me the old kick is just not there. I think it would be wise to be open-minded about the possibility of the converter having lost some performance as a result of being opened up twice. That is why I created this post.
10-18-2005, 04:23 PM
#4
I am sure Dave was pointing out the weld area was thin, thats why he was talking about the question about putting it back together.
if a converter gets a loss in eff. it will 60 ft. better as the engine will snap up to rpm sooner, not take longer the spool up.
You might look at the tire dia. diff. and the fact that if you might be running higher than normal line pressure you can have a crossleak in you transmission or have a clutch pack bound up or a warped front pump allowing the converter clutch apply in first gear these will all cause what you are talking about.
a loss in eff. will show up as a MPH drop and increased RPM at the traps, unless it is quite large in that case it will also allow the ET to increase
if a converter gets a loss in eff. it will 60 ft. better as the engine will snap up to rpm sooner, not take longer the spool up.
You might look at the tire dia. diff. and the fact that if you might be running higher than normal line pressure you can have a crossleak in you transmission or have a clutch pack bound up or a warped front pump allowing the converter clutch apply in first gear these will all cause what you are talking about.
a loss in eff. will show up as a MPH drop and increased RPM at the traps, unless it is quite large in that case it will also allow the ET to increase
10-18-2005, 05:33 PM
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Originally Posted by Yank
I am sure Dave was pointing out the weld area was thin, thats why he was talking about the question about putting it back together.
if a converter gets a loss in eff. it will 60 ft. better as the engine will snap up to rpm sooner, not take longer the spool up.
You might look at the tire dia. diff. and the fact that if you might be running higher than normal line pressure you can have a crossleak in you transmission or have a clutch pack bound up or a warped front pump allowing the converter clutch apply in first gear these will all cause what you are talking about.
a loss in eff. will show up as a MPH drop and increased RPM at the traps, unless it is quite large in that case it will also allow the ET to increase
if a converter gets a loss in eff. it will 60 ft. better as the engine will snap up to rpm sooner, not take longer the spool up.
You might look at the tire dia. diff. and the fact that if you might be running higher than normal line pressure you can have a crossleak in you transmission or have a clutch pack bound up or a warped front pump allowing the converter clutch apply in first gear these will all cause what you are talking about.
a loss in eff. will show up as a MPH drop and increased RPM at the traps, unless it is quite large in that case it will also allow the ET to increase
What about PCM scanning software? Is there anything it could see that would point to such problems?
As far as tires are concerned the MT 17" ET Street Radials are listed as being 26" tall with an 82 inch circumference. The 16" ET Streets I have now are listed as 26.2" tall with an 82 inch circumference.
No really significant change in tire diameter.
10-18-2005, 07:40 PM
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Was gonna say exactly what Yank said. Splitting a converter does fark all to its performance, providing you have enough weld space to put it back together. Also, splitting and re-welding actually brings closer together all the internal bits theoretically making it tighter.
If you really want to monitor your converters performance, find someone who can do a tranny log via HPTuners at the track. Measure the trans input shaft RPM and divide it by the engine RPM to get a % measurement of efficiency. Alternatively, log the TCC slip RPM.
A tight 3000 stallie should slip no more than 200-300RPM at 6000RPM in 3rd gear, yielding somewhere around 96% efficiency.
A stock stall should slip 100-150RPM for 98% efficiency.
A 4000 stall should slip 400-500RPM for 94% efficiency.
Anything less than 93% efficiency even a modified NA LS1 is a bin job IMHO. Nitrous and FI will, of course, slip the converter even more - thats why I said NA.
This is how I measure it. I know converter spintrons/dynos/whatever they are called are more accurate.
If you really want to monitor your converters performance, find someone who can do a tranny log via HPTuners at the track. Measure the trans input shaft RPM and divide it by the engine RPM to get a % measurement of efficiency. Alternatively, log the TCC slip RPM.
A tight 3000 stallie should slip no more than 200-300RPM at 6000RPM in 3rd gear, yielding somewhere around 96% efficiency.
A stock stall should slip 100-150RPM for 98% efficiency.
A 4000 stall should slip 400-500RPM for 94% efficiency.
Anything less than 93% efficiency even a modified NA LS1 is a bin job IMHO. Nitrous and FI will, of course, slip the converter even more - thats why I said NA.
This is how I measure it. I know converter spintrons/dynos/whatever they are called are more accurate.
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10-19-2005, 11:39 AM
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Is there any way to detect a crossleak, pack binding or a warped front pump causing clutch lock?
That last one really has me wondering. The clutch engauging would certainly cause the kind of problems I have and could go unnoticed. How common is it for this to happen.
To tell you the truth I have no idea what happens inside a converter to engauge the clutch.
That last one really has me wondering. The clutch engauging would certainly cause the kind of problems I have and could go unnoticed. How common is it for this to happen.
To tell you the truth I have no idea what happens inside a converter to engauge the clutch.
10-19-2005, 12:28 PM
#9
You can drop the transmission pan and remove the 2 bolts that attach the TCC sol. to the valve body at the front, pull the sol. loose and put the transmission together
run the car and see if the 60 ft returns
you will not have any converter clutch lock-up apply this way as there is no fluid pressure retained in the TCC system
so do not drive too far on the highway as overheating might happen
run the car and see if the 60 ft returns
you will not have any converter clutch lock-up apply this way as there is no fluid pressure retained in the TCC system
so do not drive too far on the highway as overheating might happen
10-19-2005, 02:43 PM
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Originally Posted by Yank
You can drop the transmission pan and remove the 2 bolts that attach the TCC sol. to the valve body at the front, pull the sol. loose and put the transmission together
run the car and see if the 60 ft returns
you will not have any converter clutch lock-up apply this way as there is no fluid pressure retained in the TCC system
so do not drive too far on the highway as overheating might happen
run the car and see if the 60 ft returns
you will not have any converter clutch lock-up apply this way as there is no fluid pressure retained in the TCC system
so do not drive too far on the highway as overheating might happen
How many 1/4 mile passes do you think I could safely make this way?
I am going to a track this weekend and plan on trailering the car. Would 4 or 5 passes be too much?
