SOme help please ?

[coony278]

I am having horrible luck with my car lately, The car has a BTE 8" converter. I was having some trouble with reaction time on the car.

I called up my converter guy and he suggested we cut the converter open and see if something was going wrong. I also told him that by my calculations the converter was slipping about 22%.

They cut the converter open and said there was nothing wrong with and suggested that I change to a hard hit stator.

I reinstalled the converter , and also changed my rear gear ratio because of his suggestion from a 4:11 to a 4:88.

Now I cant get the car to hook , it just wont do it on the tire I have. The couple of time I have got the car close to hooking , the hit is Violante. Feels like car is coming apart.

Now with the converter changed I lost 2 mph at the stripe and about .2 tenths in e.t.

The car is a coupe mustang with a sbc and a glide. Weights 2975lbs with me in it ready to race.

I run the 7.0 index class.

My trap RPM is now 7200 rpm at 95.6 MPH with a 26" tire and a 4.88 gear. 1/8th mile.

By the wallace calculator my converter slip is 15.6 %. With no slip I should be crossing the line around 6400 rpm.

Anyway sorry for the long post , but if anyone can steer me in the right direction I would appreciate it. I had a car that was working ok , now I have a car that wont work at all.

The converter just doesn't seem to be right to me , maybe i'am looking in the wrong direction?

[supernova]

What was the rpm before the changes? Are you sure it not the trans slipping? 4.88s and a 26" tire may be some of the speed and time loss. I tried a set of 4.56s and a 26" tires in my SB car and went back to the 4.10s. It slowed down because it over powering the small tire, too much leverage, lots of wheel spin. I don't remember how much it was over 10 yrs ago.
You didn't say what the stall was or is now. That might be helpful to know. The % of slip does sound high but putting #'s in the wallace calculator might not be correct.
If it's trying to hook and violently shakes the car, I would say have the trans looked at.

[coony278]

Had the trans looked at when changed the converter. The rpm before the change I went through the lights at 6400rpm now I go through at 7200.

The converter was stalling 5400 before the change now it goes to 5100.


I really believe the trans is good. It inly has 16 passes on it since the redo and freshen.

[John_Heard]

Did they change it to spragless also?

You made a number of changes all at once there - Gear and converter... would have been nice if you had tried the converter before swapping out gears. If this is a small tire car (26") I'd consider dropping back on the gear to the 4.10's to take some of the hit out.

Nothing wrong at all with some slip in the converter, bottom line is what does the car want to go fastest? People make the mistake all the time chasing slip numbers and they forget to watch the time slip. Even at the highest ranks in Pro Shootout racing (Marty has some stories on that subject!).

[coony278]

I am really not concerned with the slip number , but a friend that has been helping me with the car is. He thinks that is what is wrong with the car. However I believe it is to much gear for the car.

The car ran the number with the 4:11 gear, and would hook fine. Now it is a no go. I really believe I can go back to the 4:11 and car work again , but they tell me that the reaction time will go away again.

The reaction time problem is what has started all this, with the 4:11 gear and the regular stator I could not get better than around a .450 light out of the car just putting it in the light. I made the changes and now just bumping into the light I get .408 , .405 ect. lights out of the car.

The reaction time of the car seems to be fixed , however the rest of trip down the track is way off now.

So really the question is do I put the 4:11 back in and try and see if the car will work or do I upgrade to a larger tire ?

[Marty Chance]

first try putting the old gear back in (4.11) and the increase in stall speed may take care of the reaction time problem. Let us know what the result is. Remember the golden rule ...... only one change at a time.

[coony278]

Yep I have always went with this rule , but with my converter guy and a friend harpen on me to change the gear , I went ahead and done it.

Now I guess I will put back the easiest change ( gear ) and go from there , thanks guys , always helps to talk it out !

[coony278]

Well I put the 4:11's back in and wow , the car is now in it worst state. It will hook now , but the 60' is way off , dropped from a 1.50 to a 1.58 . And now i'am .20 slow from what I previously was with the original stator in the converter.

The weird thing is the mph is there to run the number , but I just couldn't get the car to do it tonight.

I'am stuck I don't know what to change , or check, I cant believe the hard hit stator slowed the car down but it did , and the 60' is what has got me , why did it drop off so much , the reaction time is better , in the teens now. I just dont know what to do.

Any suggestions ??

[supernova]

The car ran better with the old converter set up. I would have to put it back the way it was. Or find a more reputable converter guy.....

[Marty Chance]

what kind of shocks and struts are you running? you may have a suspension issue

[coony278]

the car has coil overs on the front with stange adjustable struts, The rear has strange adjustable shocks with solid links ( hiem joints ), The car is a 87 mustang.

I'am changing the rear tires on the car now , to a 28 x 10.5 and putting the 4:88's back in. I believe it may be spinning.

I have tried about every setting I know to try on the suspension.

I ran he car this past weekend , it did better on race day. I believe they prep the track better than on a test and tune. The 60' was 7 numbers better on race than on the previous TNT day.

Going to try the bigger tire and see if will work better. I believe the hard hit stator is just hitting the little tire so hard it wont hold.

[Marty Chance]

good plan, glad to see you are going to try to make the higher flash stall converter work for you.

[bracketracer]

Get someone to get some vid of the car on the starting line....

[coony278]

I will get some video this weekend. We have a big 2 day race at Holy Springs , 1500 to win each day , hope to bring some of that money home with me !

Just praying that the bigger tire and the 4.88's work well in the car.

[coony278]

Well forgot the video camera , but didnt really make a difference.

The car spun every pass , wouldnt run the number , it is just off. Iam taking the converter out this week and sending it to someone else.

I worked with car and it finally came around on the secound day of racing and I got it to where it was close to hooking. Would run 7.05 pretty consistent but in the 7.0 class that is not going to cut it at all.

Before I statred all this car would run 6.80's pretty easy , but now it will only run 7.05 the best it can do all out and out.

Iam going to change the converter back to something else. iam tired of this thing being so hard to hook , and wont run !

Unless someone has a better suggestion?