4.10 and Auto Tranny Shift Smoothness = other GT owners' opinions!

Hey guys. I have a 4.10 rear and an automatic transmission. My car seems to shift more jerky since the 4.10 install even though I have it set to 4.09 with my Diablosport Predator tuner.

I have made sure my shift settings are setup for the smoothest possible shift, such as setting all partial-throttle shift PSI to Stock, leaving the Torque Modulation to stock, and so forth. The Predator at this point does not allow for partial-throttle shift point adjustment, which I think could help.

What I'm wondering is do any of you other auto tranny/4.10 owners have shift issues? The issues I have specifically are:

1: Car hangs on to the gear it's in for too long (example: When in Overdrive, if I let off the gas, the car won't start coasting until about 5 seconds after letting off. It just won't release the gear).

2: Shift from gear 3 to 4 seems rough, especially when driving slower. It is like the car shifts from 3 to Neutral then to 4, but does this quickly. That may be a bad example. In other words, it shifts hard from 3 to 4, even though I'm driving slowly.

3: The car jerks when in overdrive at lower rpms when I let off the gas quickly. Instead of the transmission smoothing out/releasing and letting the car roll, the car jerks like I'm tapping the break almost. THEN it smooths out. Sort of like if my shifter is in 2nd and it's forced to "hang on" to 2nd when letting off at high RPMs, and it makes the car nose dive a little.

ALL the issues occur when driving the car around normally/partial-throttle. When horsing around or giving it a lot of gas, it shifts great all the time.

I could drive it harder all the time, that would fix my issue. I feel like this is unnatural though. Is the computer in the car just hard-set to 3.27 gears for the partial throttle shift points, and that is what is causing my issues? The transmission just is not smooth with the 4.10s, and when I had the 3.27 gears in it never had this problem.

I am probably going to go back to the 3.27 gears if I can't find a good solution for this problem. I'd love to leave the 4.10s in though, they are a great power gear.

Any credible info on this would be helpful. Thanks!

I had 410's in my auto and hated them, same issues, I switched to 373's and couldn't be happier, kb helps though ! I'm no expert, but it sounds like the torque converter lockup or something....

I have 4.10's in my automatic GT. I went with a Diablo sport chip and CMR tune to adjust everything for the gears. I couldn't be happier with the way my car shifts. Nice firm shifts, no hesitation. IMO, the chip is a better way to go if you have gears and an automatic.

Chip shift points/shift PSI?

May I ask, do you know what PSI your chip sets your shifts to, plus the shift points (if it modifies those at all)? I may use that information when Diablo updates the predator revision to do partial-throttle shift points.

If my car shifts while I'm letting off the gas, it is a harder shift, like something in the transmission isn't synching right. It almost seems like 4.10 is too steep for the auto tranny, at least for normal everyday operation. I just don't see how though.

o3redfire, thanks for the input. If it is the torque converter doing funny things, what would be a fix for that? A new one?

How many miles? When was the last time you changed tranny fluid and filter? Is fluid level low?

Mine shifts great with JMS chip.

No, I haven't changed them.

I have 38,000 miles on the car. I have not changed my transmission fluid or filter. The fluid level is not low last time I checked.

I agree with the others, get a dyno tuned chip from a reputable tuner in your area, I believe they can program tc lockup.

This sounds like the exact same thing my car does, although I have the stock 3.27's. I posted a thread about it a week or so ago, and the main thing everyone said was that it was the stock torque converter. Just like yours though, if I'm on the gas hard, it shifts fine.

Since you already have a Predator, a CMR dealer can do a custom tune for it the same as for a chip.

The fluid should be changed every 30K miles. Even if this isn't the root of the problem it could be contributing. I would get it flushed soon.

Possibly the stock torque converter then?

Thanks rjstaaf. I will get that done asap.

So would I be better off upgrading my torque converter then, since the stock one clashes with 4.10? Or should I just get the one I have tuned?

Torque Converters and their install aren't exactly cheap, are they?

I would get the fluid flushed first and see if that helps.

I will admit I know nothing about these hand held tuners but, did you load a performance tune over the stock tune? Seems like a lot of people are having issues like this and wind up trying to put all the settings back to stock. Is there not a way to leave the stock tune and just change the gear ratio?

EDIT: Just got a reply from Diablosport. They said that you can modify the stock tune and just change the gear ratio. I believe he said it was under Factory HP whatever that means. What I would do to troubleshoot the problems you are having is to reload the stock tune and modify just the gear ratio and have your transmission fluid flushed.

Ha ha, oh boy. Here we go.

I would do that, but the only problem is the Factory HP Tune in the diablosport predator has a glitch where the rear axle ratio will not work. If I install the Factory HP Tune and set my rear gear ratio to 4.09, my speedo will show me going 80 when I'm really going 60. So, it doesn't work. Otherwise I would do that, since I don't want to adjust my spark advance, fuel ratio, etc. Just rear gear ratio pretty much, and the traction control lock, etc. Minor stuff.

I just don't get why it has taken Diablosport FOREVER to get the fix for that out. That was 6 months ago when I had this problem, and they still haven't put an update out that fixes their $400 tuner. I'm beginning to wonder if I should have gotten another programmer instead of the diablosport, but who knows. Maybe they all have some sort of glitch - after all, it is software.

The diablosport is very easy to use, I'll give it that. Plus if I decided to go with custom tunes from them, if they tuned it up for me and did a good job, it would be worth it. I may find out, but that costs another $120 on top of the $400 I've already dished out for it, so...

Anyway, you had a great suggestion man. It just won't work because of their glitch. Sorry.

See I said I didn't know much about the hand held tuners That does tell me though that maybe I don't want the Predator. I have been looking at the Predator as well as the SCT Xcalibrator.

The Xcalibrator can be had for about the same price as the Predator.
http://www.modulardepot.com/product_info.php?cPath=21_47&products_id=219

I don't think the predator is a bad tuner, I just think it has a glitch they haven't taken care of yet. As far as I can tell everything else works well, so I can't complain too much. I think that the product should work completely when I get it though, not 95% complete.

What can be done to make the automatic smoother, besides regular upkeep? Since I have 4.10s and they put more stress on things, would an aluminum driveshaft take out a lot of that jerky feeling since it would be lighter? Or should I just invest in a torque converter, or some sort of kit, or something?

I'm not aware of all my auto tranny options. At this point I'm even looking into selling my current GT for a stock 5 speed GT that I can drop some 3.73s in and weld in some Flowmasters. If I could find one that I could get an even trade on, or one that I could just out right buy for 11,000-13,000, I would consider it.

If my transmission shifted more smoothly I think I would be really happy with my current car though. So, any ideas for transmission shift smoothness will help. As I said, I'm going to get all the maintenance stuff taken care of as soon as I can. Other than that, and making sure all my shift firmness settings are all on "Stock", what else could I look into?

Thanks!

If you want all the automatic transmission settings to be stock set your Predator to manual. That way there will be no automatic transmission settings loaded. The ability to adjust the factory HP tune for speedometer correction using 4.10 gears works fine on my Predator with revision r50d, I did not know Diablo had a glitch with it. If you want to try r50c I can e-mail it to you. It allows for adjustments to the factory tune also.

If you're looking for modifications to make your 4r70w equipped automatic GT shift better, just read my signature. Also, keep in mind that what Rjstaaf has informed you about concerning flushing the fluid at LEAST every 30k is more true than you know.

If you want the automatic to shift better/harder, I suggest the following.

Transmission cooler - This is a must have modification for any automatic transmission in a high performance vehicle. Heat is the number 1 killer of automatic transmissions. A good transmission cooler will reduce the heat greatly and extend the life of your transmission.

Torque converter - This piece will be an expensive upgrade but well worth the money. Go no less than a 2800 stall or you will not be happy.

Shift Kit/ Performance valve body - There are numerous shift kits and valve bodies on the market for the 4r70w transmission. Any performance valve body from some place like Lentech Transmissions, Performance Automatic, or Art Carr will be a nice piece. Personally recommend something called the "jerry mod". I have it and love it. It's called the Jerry mod because Jerry Wroblewski, the same man who designed the 4r70w transmission for Ford designed this shfit kit as well. It invovles modifying your stock valve bodies seperator plate and accumulator pistons springs. Nothing major. If you're not mechanically inclinded, then any transmission shop can do this for you in a couple of hours. Go to www.tccoa.com and read up on their tech articles for the 4r70w transmission.

Note: It is a Thunderbird and Cougar club, however, the tech articles are no different when it applies for the 4r70w transmission.

Custom Tune/Chip/EEC flash. The 4r70w is an electronically controled automatic transmission as I'm sure you know. Therefore, it is largely dependant upon computer programing for accurate shifts and response. When doing big changes to a transmission, such as torque converters and rear-end gear changes, you alter torque levels and shift points which can result in poor performance unless if the computer's programming is upgraded to meet the new specs. I have a custom program from SCT(Superchips Tuning) and I have no problems with my speedometer or shifts at all.

Other transmission mods to consider:

Aluminum Driveshaft - This piece will help to lighten the weight of the drivetrain and reduce vibrations during shifts. You will need to buy one that is designed for the five speeds and swap yokes as no one that I know of yet makes an aluminum driveshaft for the automatic GT's just yet.

Deep Transmission Pan - Although not needed, this is not a bad idea to invest in either. It will allow the transmission to hold another 1+qt of transmission fluid, which will help to reduce heat and stress on the transmission by adding more fluid to the mix. Not only that, but many of these aftermarket pans have a drain plug that makes the task of changing your transmission fluid easy as compared to spilling fluid all over yourself due to the lack of a drain plug on the stock pan.

Full Synthetic Transmission Fluid - Many people don't understand how important synthetics can actually be when adding life and protection to a vehicle, especially in the transmission. The 4r70w transmissions are to be used with no less than Mercon V, which is semi-synthetic to begin with. If you can afford it, I would chose something that is fully synthetic like Amsoil universal full synthetic automatic transmission fluid. It will help to reduce wear and tear while reducing heat levels. This is what I'll be switching to my next fluid flush.

Thanks for the help! Here's a question:

Thanks for that great post. That should help me out a lot. I'll do some research on those topics/products you mentioned and see what I can come up with.

I'm looking at this page: http://www.artcarr.com/catalog/ford-B-D-H.php

What would product number B-21366, the AOD MANUAL /AUTOMATIC VALVE BODY 1,2,3 FULL MANUAL SHIFT do for an automatic?

Thanks!

A full manual shift valve body will allow you to do all the shifting of the automatic transmission yourself. Hence, the term "manual". However, because it is "full manual", I think you will have to do ALL the shifting yourself as this type of valve body will no longer allow the computer to engage/disengage and shift gears on its own. At least, I'm assuming the term "full manual" indicates this type of function.

There are many guys running these types of valve bodies without any problems. I recommend if you go this route, get a nice aftermarket shifter to take advantage of the new shifting capabilities. Its really up to you. If you like shifting the car yourself and don't mind doing it all the time, then get a full manual valve body and have a ball. If you want the computer to shift on its own, but still shift harder, then I recommend a performance valve body, not a full manual valve body. You can try emailing Art Carr and asking them which valve body is best for your application. Also, try checking with Lentech Transmissions and Performance Automatic.

www.performanceautomatic.com

http://www.bmsproducts.com.au/catalogue.htm