GM 4L60E auto for road course use

[260DET]

Looking ahead to a possible 450hp LS1 engine change and wondering if the 4L60/65E can be modified to give nice smooth clean downshifts under heavy braking from high speeds. There is a lot of stuff advertised - big power upgrades, manual shift bodies and shifters, stand alone shift management and so on but never any mention other than for street or drag use. I'm wary of asking advertisers if their stuff will suit my purpose, any suggestions?

[randy 77zt]

you need to find somebody that has actually done this so you wont be the test dummy at your own expense.i have a friend with a 66 mustang with a built c4 and he has had 2 problems.he needed a deeper pan with fluid pick up at the bottme -it was sucking air.the fluid needs a large cooler-it runs hot.plus you need big brakes.some of the software you can get for chevy lsx lets you wotk on the auto trans functions.newer trans have functions like adjustable line pressure,torque converter lock up,fluid temp sensors,shaft speed sensors and lots of fun stuff.but some kind of paddle shifting would be fun

[260DET]

I'm in love http://www.tciauto.com/Products/TC-%27Street%20Transmissions%27-4.aspx Pro touring is some sort of road course circuit racing series isn't it. Start saving the dolla Richard

[hoov100]

A computer controlled 4l60 can be tuned for a smoother downshift by just taking some of the line pressure out when you let out of the throttle. But I still think a stepper motor hooked to the throttle that's activated for half a second when the clutch pedal is pressed would be a better bet.

[260DET]

A computer controlled 4l60 can be tuned for a smoother downshift by just taking some of the line pressure out when you let out of the throttle. But I still think a stepper motor hooked to the throttle that's activated for half a second when the clutch pedal is pressed would be a better bet.

 

Yeh am still looking at a throttle blipper but with the present setup its awfully complicated and verging on the impractical to do something electrical, although a mechanical device may be practical. Like a lever or clutch pedal operated cable device. The LS auto idea is something for the future but its viability is relevant now. Like the VG could be changed to drive by wire operation if the LS auto idea is not viable.

[hoov100]

Yeh am still looking at a throttle blipper but with the present setup its awfully complicated and verging on the impractical to do something electrical, although a mechanical device may be practical. Like a lever or clutch pedal operated cable device. The LS auto idea is something for the future but its viability is relevant now. Like the VG could be changed to drive by wire operation if the LS auto idea is not viable.

 

I guess this is all going to break down into what you want to do and what you can afford. While the built LSx auto option does look promising, it's going to be the most expensive and time consuming. while going fly by wire would take more time to setup and work the bugs out of, it's options are only going to expand as more and more companies are utilizing the DBW for things like traction control, rev matching, actuation smoothness..etc. If you want to get really nuts, you could go drive by wire and use two paddles on the steering wheel to actuate two pneumatic cylinders which will change the gear for you as well.

[260DET]

Had the chance to have a long talk with another southern hemisphere racer who has used an auto for several years and loves it. He does well in open competition too, at a higher level than I am so its the plan, a NA LS with a modded 4L60E after I do Bathurst (300kph max OMG?) over easter next year. The aftermarket support for these autos is incredible so I'm confident of getting a durable and suitable setup. Gotta start saving and give up hookers and coke

[Savage42]

I've been thinking of doing a paddle shifter setup in my car. Maybe in the next few months.

 

http://www.ls1tech.com/forums/automatic-transmission/764919-paddle-shifting-4l60e-4l80e.html

[260DET]

Yeh I'll be looking at the paddle shifter option too but more as a DIY project at least for the hardware. A couple of momentary switches, cut some aluminium into a paddle shape..............

[260DET]

Now that the Z has a LS3 in it the 4L60E option is on, have spoken with someone who builds racing transmissions and he is going to sit down and think the requirements through to come up with a suitable package. Aftermarket circuit autos are almost non existent here so it's different for him but he's keen to do it.

 

Without finalising anything we talked about having a clutchless 9" converter and a manual bump shift setup. Once it's all been worked out and decided on I'll fill in the details here. Comments welcome in the mean time.

[tube80z]

Not knowing much about circuit autos I'm interested.  Do you still have the converter or is this a straight drive like a circle track setup?  Also curious about weight.  I'm currently setup to use a dog ring 4-speed but could see swapping if this looks better.

 

Cary

[260DET]

It's still all to be decided Cary, I have two shops working on a proposal and hope to get them to cooperate to get the best possible outcome. Apparently the 4L60E is considered fragile but doable for my 500hp application, it will weigh around 70kg all up compared with 110kg for the recommended 4L80E which is just too heavy. As a comparison the Z32 manual box I have weighs around 55kg.

 

It will have a fully operational converter which I guess is needed for speed variations from loading the car onto a trailer to flat chat down a long straight. Heat management is going to be critical in that situation.

[johnc]

I would run a converter - the torque multiplication helps.  Make sure its a full manual valve body.  I autocrossed a Corvette with an auto and the valve body would hold the gear on upshifts but it would downshift if it thought it was needed.  That led to a lot of lurid slides when the transmission downshifted at a corner apex while I was squeezing on the throttle.

[260DET]

Yep, it's going to be a full manual sequential shift auto using a stick in the usual place, I don't like paddle shifts but that is an option. At present, subject to further advice, the torque converter will be a 10" diameter job with a lockup, stall around 2,500RPM.

 

Have started the parts collection by ordering a aftermarket six element planetary gear set which raises the 2/3 gear ratios to give a more competition orientated 2.84/1.55/1.00/0.70 ratio set. Which with a 3.9 diff and the usual tyres will at 6,000RPM give gear speeds of 64/118/183/262KPH. Not ideal but close enough.

Edited February 6, 2015 by 260DET

[tube80z]

You're going to run an LS3 aren't you?  You should be able to run those 6500 stock I guess that's only roughly 20k or so, which may not be worth the extra wear and tear.  Keeping the revs down with help with oil issues too.

 

Cary

[260DET]

Yep, 6500RPM is plenty given the torque spread of the LS3. Besides, the 4L60E is not the strongest auto around so there's that to consider too.

[260DET]

Trying to find out the details of this car's auto.

 

[260DET]

Have reached an impasse with the 4L60E, down shifting through the gears with engine braking appears to be a crucial weak point. Sonnax kindly offered some advice which would help but the basic mechanicals remain the same, they have no plans to bring out any mechanical improvements as they have done with some other components.

 

So it's back to the drawing board to look at the 4L80E, might open a new thread for that.

[Meatwad]

As a guy who has dealt with 4l60e's in the past and have a close friend who builds racing GM transmissions, I'm confident when I say to stay away from 4l60e's if you get traction. Even built ones are still incredibly weak no matter who builds it with whatever parts.

[260DET]

Yep, my conclusion is that to build a reasonably reliable 4L60E transmission for my purposes would involve a virtual replacement of every significant OE component. And that would not give reliable engine braking. So a 4L80E it is.