Going slower after TH400 install
Going slower after TH400 install My 4L60 took a crap on me so I went with a PTC TH400 with a brake and a PTC 4400 stall.
Before the swap the car went consistent 11.40's @ 116-118with a 1.59 60'. Now leaving off the brake around 4K RPM I am only getting 1.7x 60' and running 11.80's @ 114-116. The TH400 has a standard 2.48 first gear. I am running a 3.70 gear in the 9" and a 28" tire.
Does this seem common? Should I re-tune the car with the new trans/converter setup? Any recommendations?
Thanks,
Leo
Before the swap the car went consistent 11.40's @ 116-118with a 1.59 60'. Now leaving off the brake around 4K RPM I am only getting 1.7x 60' and running 11.80's @ 114-116. The TH400 has a standard 2.48 first gear. I am running a 3.70 gear in the 9" and a 28" tire.
Does this seem common? Should I re-tune the car with the new trans/converter setup? Any recommendations?
Thanks,
Leo
Launching!
Joined: Dec 2007
Posts: 255
Likes: 4
From: greenbrier tn
What size is the converter? 10"? Also what stall was your old converter? Plus the 4l60 has a 3.08 1st gear I think. Your new set up may be too loose and slipping some. It is critical that you tell PTC the full spec"s on your set up. Have you tried foot braking the new stall at around 1800RPM and running that way at all?
Last edited by bada; Aug 4, 2008 at 12:15 PM.
someting sounds off.I have 451 rwhp and trap 128 with the same tranny.What is your race weight and what was the D/A at that track that day?Maybe the converter is a bad match for your setup.I am running 410`s with a 26 inch tire maybe you need more gear
I had the same power numbers with the 4L60 and never trapped in the 120's on motor.
Weight with me in it is 3800 lbs.
Not sure of what the DA was, but it was at Norwalk this past weekend, racing at 2 am and 5 am so it was cool out...great air.
I was figuring more gear.
The MPH has always been low for the car. It is heavy @ 3800 lbs. PSJ's Camaro was very similiar to my setup (Same engine/head/cam/intake) and he was running 11.00's @ 120+. Though his raceweight was alot less than mine. Now he did have 4.10's and I have 3.70's
What size is the converter? 10"? Also what stall was your old converter? Plus the 4l60 has a 3.08 1st gear I think. Your new set up may be too loose and slipping some. It is critical that you tell PTC the full spec"s on your set up. Have you tried foot braking the new stall at around 1800RPM and running that way at all?
Old converter was right around the same stall speed.
I have not tried leaving softer at all. Well, I guess i did. I went from matting it on the brake and leaving at 4600 to just getting to 3K and really didnt have alot of change.
A 3.70 and a 28" tire is a little much, thats what I use and go 150mph @ 7200tpm 
While not optimal it shouldnt have killed the car that much if thats the same gear/tire you ran before. The 3.30 or whatever 1st gear probably helped out some in the 60' department though..
Also use a 2 step with the brake around 3000rpm, dont just leave WOT with the brake. If the converter is close using the brake or footbraking wont make a huge difference in ET.
Not to mention the weather, check the DA. MPH shouldnt have been affected much if the converter is halfway decent.
While not optimal it shouldnt have killed the car that much if thats the same gear/tire you ran before. The 3.30 or whatever 1st gear probably helped out some in the 60' department though..Also use a 2 step with the brake around 3000rpm, dont just leave WOT with the brake. If the converter is close using the brake or footbraking wont make a huge difference in ET.
Not to mention the weather, check the DA. MPH shouldnt have been affected much if the converter is halfway decent.
A 3.70 and a 28" tire is a little much, thats what I use and go 150mph @ 7200tpm While not optimal it shouldnt have killed the car that much if thats the same gear/tire you ran before. The 3.30 or whatever 1st gear probably helped out some in the 60' department though..
Also use a 2 step with the brake around 3000rpm, dont just leave WOT with the brake. If the converter is close using the brake or footbraking wont make a huge difference in ET.
Not to mention the weather, check the DA. MPH shouldnt have been affected much if the converter is halfway decent.
While not optimal it shouldnt have killed the car that much if thats the same gear/tire you ran before. The 3.30 or whatever 1st gear probably helped out some in the 60' department though..Also use a 2 step with the brake around 3000rpm, dont just leave WOT with the brake. If the converter is close using the brake or footbraking wont make a huge difference in ET.
Not to mention the weather, check the DA. MPH shouldnt have been affected much if the converter is halfway decent.
With the 4L60 I went 10.54 @ 124 with a 100 shot. With these times I am thinking Ill need the 200 just to get back to that kind of ET
We have the Pontiac Nationals this weekend and I am going to try the spray and see what happens. I am having a feeling that the car isnt going to do what I was hoping for though.
The car feels like it pulls harder than it did with the A4, but obviouslly the ET says different. Maybe that is just because the shifts are more positive now?
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Verdad Gallardo The converter is supposed to be the best weld together from PTC. Havent had anything but good results with them so far. I know everything is setup to be optimal on the 200 shot.
With the 4L60 I went 10.54 @ 124 with a 100 shot. With these times I am thinking Ill need the 200 just to get back to that kind of ET
We have the Pontiac Nationals this weekend and I am going to try the spray and see what happens. I am having a feeling that the car isnt going to do what I was hoping for though.
The car feels like it pulls harder than it did with the A4, but obviouslly the ET says different. Maybe that is just because the shifts are more positive now?
With the 4L60 I went 10.54 @ 124 with a 100 shot. With these times I am thinking Ill need the 200 just to get back to that kind of ET
We have the Pontiac Nationals this weekend and I am going to try the spray and see what happens. I am having a feeling that the car isnt going to do what I was hoping for though.
The car feels like it pulls harder than it did with the A4, but obviouslly the ET says different. Maybe that is just because the shifts are more positive now?
I'm not sure you can add much gear, I just changed mine over from a 6spd to a th350 with 9.5" 4000 stall and a brake and mine is not even close to making it to the end of the track. I went with the converter they recommended for my setup and it seems way off. I also have 4.30's and 28" qtp's. This same setup with my 6spd has run just over 124mph but after the swap I'm out of gear at the 1000ft. Everything I've read says I should run 124 for a max mph with these gears, but it's not even close
Historically, in other cars I've fooled with... the TH400 transmo is a TANK(won't break), but it's always a little slower ET-wise. Normally, it's geared higher and weighs a little more too. I may be off, just my thoughts
Launching!
Joined: Dec 2007
Posts: 255
Likes: 4
From: greenbrier tn
Before you do anything you NEED to tune out the automatic trans settings in your computer. You can either swap to a m6 tune or just remove all the 4l60e stuff.
This MUST be done or your car will go into a "limp" mode. It doesnt see the trans shift out of park so it throws everything off.
Ask me how i know lol. I just swapped in a th400 last year and with stock tune car went 12.6's and once i swapped to a m6 tune to delete the trans codes i ran an 11.9's. Nothing changing except for removing the 4l60e trans stuff
It was a complete turd before tuning out the trans stuff.
Do that ASAP and you will notice a HUGE difference.
Sorry i didnt see this earlier.
This MUST be done or your car will go into a "limp" mode. It doesnt see the trans shift out of park so it throws everything off.
Ask me how i know lol. I just swapped in a th400 last year and with stock tune car went 12.6's and once i swapped to a m6 tune to delete the trans codes i ran an 11.9's. Nothing changing except for removing the 4l60e trans stuff
It was a complete turd before tuning out the trans stuff.
Do that ASAP and you will notice a HUGE difference.
Sorry i didnt see this earlier.
Joined: Nov 2001
Posts: 10,023
Likes: 6
From: LT1 land...the "409" of the 90s!
I agree you must get the Trans stuff turned off.
I went from 11.4s N/A to 10.9s N/A swapping from a 4L60E to a TH400 keeping the 3.73 gears. I am trapping 121MPH so far and running a very tight 8in conveter coming out at 4k
I went from 11.4s N/A to 10.9s N/A swapping from a 4L60E to a TH400 keeping the 3.73 gears. I am trapping 121MPH so far and running a very tight 8in conveter coming out at 4k
The converter is probably too tight to be honest.
I have one for sale that would probably work like a charm for your setup, I went 10.50's with it n/a off the footbrake with th400, flashes to about 5400 but for what you're doing it should be right on.
Works good with 100 shot too, any more then that and it's too loose.
You have gearing/tire/converter size for 300 hp more then you're making, that's what's slowing it down.
I have one for sale that would probably work like a charm for your setup, I went 10.50's with it n/a off the footbrake with th400, flashes to about 5400 but for what you're doing it should be right on.
Works good with 100 shot too, any more then that and it's too loose.
You have gearing/tire/converter size for 300 hp more then you're making, that's what's slowing it down.
Before you do anything you NEED to tune out the automatic trans settings in your computer. You can either swap to a m6 tune or just remove all the 4l60e stuff.
This MUST be done or your car will go into a "limp" mode. It doesnt see the trans shift out of park so it throws everything off.
Ask me how i know lol. I just swapped in a th400 last year and with stock tune car went 12.6's and once i swapped to a m6 tune to delete the trans codes i ran an 11.9's. Nothing changing except for removing the 4l60e trans stuff
It was a complete turd before tuning out the trans stuff.
Do that ASAP and you will notice a HUGE difference.
Sorry i didnt see this earlier.
This MUST be done or your car will go into a "limp" mode. It doesnt see the trans shift out of park so it throws everything off.
Ask me how i know lol. I just swapped in a th400 last year and with stock tune car went 12.6's and once i swapped to a m6 tune to delete the trans codes i ran an 11.9's. Nothing changing except for removing the 4l60e trans stuff
It was a complete turd before tuning out the trans stuff.
Do that ASAP and you will notice a HUGE difference.
Sorry i didnt see this earlier.