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Topic Review (Newest First)
08-06-2013 10:11 AM
Originally Posted by ASE Doc View Post
I'm not sure what all the differences are between the V6 and V8 units. .

The only thing different is clutch pack count and a thicker pressure plate!
08-06-2013 09:19 AM
ASE Doc I'm not sure what all the differences are between the V6 and V8 units. I know that on the 700R4 the valvebody itself is different, as well as the clutch setups. Fortunately for us, these units have been upgraded so much since they were introduced, we can pretty much build then anyway we want with the right combination of parts and mods.

I ordered the ATSG manual for my trans. This winter I just used the factory service manual but it is limited, especially with the upgrades and changes made since 87. From what I understand, the ATSG books are the best.
08-05-2013 04:34 PM
jokerZ71 Yep.I've heard the same.This 1 is supposedly from an S10.From what I hear it has a different valvebody calibration & 1 or 2 less clutch plates than used on fullsize app.IDK that to be accurate.I'll find out when I tear it down.I'm gonna order the manual for it before I try anything.
08-05-2013 04:23 PM
ASE Doc What I know of the 4L60E is that the aluminum valve body has wear issues. I don't remmber the specifics. Only that some of the valvetrain bores tend to wear and those valves then catch and stick in the ridges of the worn bore. I remember doing the repairs but I don't remember which bores and gears were affected. The repair kits are available and consist of a bore reamer and an oversize valve. You can also just buy a good used or even a new valve body. Otherwise, the 4l60E is pretty much identical to the 700R4.
08-05-2013 03:33 PM
jokerZ71 Hope it all worx for ya.I've also been told that the 5 pinion rear isn't necessary.I picked up a 4L60E over the wkend for $40.Not sure which year model.I'm gonna give it a shot rebuildin it,just,for the heck of it.I've changed fluid & filter & installed a shift kit before.That is the extent of my auto trans experience.LOL. We'll see how it goes.For $40 I couldn't pass it up.
08-05-2013 02:53 PM
ASE Doc A quick update. I got the funds together and called Dana at Pro Built Automatics this past Friday. He's setting up a Hi Energy 3-4 clutch pack to fit the Smart Tech housing. He's also putting together a shift kit to help ensure solid shifts. I'm going to the Sonnax 4th servo that has 30% more apply area than the Superior unit that I'm running now. This will help prevent the 2-4 band slipping in 4th gear. A few other things I'm doing since I believe that heat played a big part in this failure are 3/8" cooler lines to replace the stock 5/16" and a larger auxiliary cooler. In fact, I may just put two 3/8" large capacity fluid to air heat exchangers in series and leave the factory integral cooler out of the loop.

I'm also going to drill a ring of small bleed holes, probably 4 or 6 total, around the housing, just below the apply plate to allow for fluid movement through the 3-4 clutches. Of course I'm also going to be sure that my TCC system working before I drive the car on the highway again.

Dana told me to forget the 5 pinion rear planet. He says it is not necessary. I did go ahead and get a used factory 4 pinion rear planet and sun gear from a local hard parts shop since I still think that mine has way too much gear lash. The replacement part showed up today and the gear lash on it is 1,000 percent better than on the one in my transmission now.
07-25-2013 07:30 AM
ASE Doc Thanks again jokerZ71 for the good info.

My 87 IROC is fitted with ACCEL DFI gen6. It's a good early 8 bit system. A bit limited on tuning in certain areas but it works very well. I built the car in '99 and custom installed the DFI system to support a high effort EFI small block. It does support TCC lockup and uses MAP and minimum engine speed as control inputs. Unfortunately, and probably for a long time even before last summer's failure of the 3-4 clutches, the TCC system doesn't work. I played with it just a minute after the build this winter and realized the 4th gear pressure switch is no good. The way that the previous trans builders had wired the TCC system was wrong anyway, like they were trying to mimic OE controls.

The ACCEL DFI's TCC control is a simple deal that just turns on the TCC above the rpm that you set in UTILITIES and turns it off above a MAP value that you also set or when rpm drops below the set point. You install a pressure switch or switches to determine what gears the TCC works in. Since mine wasn't working right, I just disconnected it shortly after the build to prevent damaging the converter clutch. Alot of good that did. I need to get the TCC working right before I do any more highway driving. My TV cable is set correctly for max TV stroke at full throttle. The TPS is set for minimum .5 volts.
07-23-2013 02:25 PM
jokerZ71 The effects would also show up more & faster with normal driving than driving driving hard.
07-23-2013 02:19 PM
jokerZ71 You said you had been doin a lot more average drivin this time.If the TC isn't unlocking during acceleration in 3rd or 4th,it can create enuff heat to burn the 3/4 clutches.Also excessive locking & unlocking can do the same.Again,not to sound like a broke record,but,your TPS can have a direct effect on this as it still controls the TCC solenoid.If voltage is low or hi.Leakageanas you stated can also create heat.The fact that you can pick up 3rd sometimes or lose it during drive just has me thinkin somethin besides just worn clutches is goin on.I think you definitely got a pressure problem somewhere wether it's a leak,sticky governor,or somethin bypassing fluid.It sounds like you got all the best mods already.if TC doesn't unlock when accelerating in 3rd or 4th soon enuff,you surely could be burnin up 3/4 clutches.With the power you have,it would be less noticeable to you than the average driver.That's where your TPS & correct adjustment is critical.For best results,it should unlock almost as soon as acceleration is detected rather than havin to mash halfway to the floor before unlocking.IDK that I'm explaining this very well as I'm not too good @ transferrin mind to keyboard.LOL.
07-23-2013 01:37 PM
ASE Doc It's possible that I put the 4th servo piston in backwards and that it is bypassing fluid when fully extended. Frustrating thing is that all gears shifted firm and solid after the build. This trans is built to take 450 hp behind my small block and hold gears to 6,500rpm. I wonder if maybe it doesn't like cruising along in OD so much. It has the transgo 3-4 valvetrain that's supposed to prevent shuttle shifting between 3 and 4 and early 4th apply. I did notice though that lately, when I try to accelerate just a little in 4th, the trans seemed to be slipping, like it was trying to downshift but wasn't completing the shift. I thought at the time it was just the TC slipping. That's part of what makes me wonder if I have a pressure loss in 4th. Low pressure in 4th will damage the 3-4 clutch pack before it damages the extra wide carbon 2-4 band I have in there. I'll find out just what's been damaged when I tear it down. The band is only about $25 so I'll have one on hand. Also thinking about going to the Sonnax 4th servo.
07-23-2013 01:34 PM
jokerZ71 How is your TC doing as far as locking & unlocking? Does it unlock if you accelerate while in 3rd or 4th easily,or,do you have to really get on it befor it will unlock?
07-23-2013 09:30 AM
jokerZ71 I definitely think somethin is up.Usually you either have a gear or not.It does just come & go unless like you said somethin is sticking,etc.If it were clutches only,i'd think 3rd & 4th would be gone regardless of manual or auto shifting.I had a 93 GMC w/ 4L60E doin the same thing.I was told by several ppl & 2 shops that it needed a rebuild.It had been parkes for 12 yrs due to this.Wasn't mine @ the time,but,left @ my home for 12 yrs.I finally bought it & got it goin plannin on a rebuild.Slammed when put into gear.1 to 2 shift harsh & extended if in D or OD.2nd to 3rd was just like shiftin into neutral.No 3rd or 4th.Then 1 day I was workin on some other problems & suddenly,bam,it shifted into 3rd'then rite into 4th.After bout half a mile it would either stop pulling or jump back to 2nd.I noticed that it would seem to mess up whenever I pushed down accelerator to a certain spot.Unplugged TPS & it shifted like a new truck.All 4 gears.Bought a new 1 & adjusted it becuz this is the 6.2 diesel.Haven't had an issue to date.
07-23-2013 09:07 AM
ASE Doc Thanks for your response Joker. This is a 700R4, not a 4L60E. It has no electronic controls, aside from TCC lock up. I know what you mean though about the affect of TPS voltage on shifting in the electronic units. With this unit however, that is not the case.

I drove the car home after work yesterday, manual shifting and not using 4th gear. While 3rd gear is definitely damaged and will need the 3-4 clutches replaced again, it had no trouble losing drive in 3rd. I'm wondering if this might be an issue related to 4th gear, which also uses the 3-4 clutches. Perhaps a pressure loss somewhere. I installed the Superior 2nd and 4th servos in my build and I wonder if I might have set something wrong or damaged a piston seal. I'm still suspicious of a sticky valvetrain in the VB. I have a trans pressure test set now and this would be a good time to use it.

I plan to collect any and all parts that I can think of possibly needing, (including a set of 9 BW high energy 3-4 frictions instead of the Alto Red, and going into the unit over a weekend. That way I can do the whole job here at the shop, including the R&R. While I'm in there, I want to go ahead and replace the rear planet with an OE 5 pinion and a new rear sun gear too. That way, assuming I get everything right this time, I won't need to go back in for a good long while.
07-22-2013 05:53 PM
jokerZ71 Check the TPS. A bad or inconsistant signal will cause you to appear to lose 3rd & OD.It will cause harsh shifts & slam when shifting from neutral or park.It will also cause gear seeking.You can be cruising @ 60 in 3rd or OD & trans will drop back to 2nd or even quit pulling all together.When it stops pulling in 3rd or OD,let off the accelerator & ease or feather back into it.It can then pick the gear up again.TPS controls your shiftpoints,TC lockup,line psi,etc.Probe the TPS wires with engine off.Readin should be near 0 @ closed throttle.Have someone slowly openthrottle & watch the meter.Voltage should steadily increase up to near 5 volts @ WOT.No spikes or flat spots.
07-22-2013 12:27 PM
ASE Doc Same old same old.

After 6 months of good shifting, my 700R4 is losing 3rd gear again. I'm trying to put together the events leading up to this new failure. I haven't been running it hard lately. I've been aware that my 60 -80 mph 6,300 rpm 2-3 upshifts may draw the wrong kind of attention and I haven't made it to the strip yet this year. The times that I have made hard shifts between 2-3 and 3rd didn't seem to have any ill effect when I checked fluid condition later. The trans has shifted beautifully since I built it, before and after hard shifting it. The one thing that I have been doing lately though is more highway cruising in OD, letting the trans auto shift into 3rd as needed for acceleration. In town, when I don't feel like manual shifting, I run in 3rd and let the trans auto shift 1,2 and 3 as needed. Just last week I noticed that my 2-3 shift was getting slushy. It had been as firm and solid as the 1-2 shift. I have also felt it binding between 2nd and 3rd(engaging the 3-4 clutch while the 2-4 band was still applied).

Then, Saturday on the way home from a short highway trip, the trans refused to shift into 3rd gear all together. I had 1-2, and no 3. Then after a mile or two limping along in 2nd, I tried 3rd and it engaged. This morning, on the way to work, the trans actually dropped 3rd gear while under way. It had engaged 3rd and 4th and I was cruising at about 60 when it just lost drive. I slowed down and dropped to 2nd and tried repeatedly and unsuccessfully to engage 3rd. I limped it to the shop in 2nd and after checking the fluid level(fluid now smelling burnt), I went to park the car and had 3rd again. I plan to drop the pan after work and check things out. I'm concerned about the 3rd clutch check ball pocket in the case. This pocket was beat up pretty good by the steel check ball they had used in the last build. I hoped that the new separator plate and torlon check ball would work out but I'm afraid that maybe the check ball is getting lodged by the damaged area and sticking. I may need to address the case damage. Otherwise, there are any number of possible causes I guess. Cross leak , lip seal, sticking valvetrain, etc.

Any of you 700R4 experts out there who have dealt with this behavior, I would greatly appreciate any input you have. It will make a short summer if I have to garage the Beast and drive my beater for a while but so be it. I'm not thrilled at the idea of having to rebuild the unit again so soon. I was planning on going back in to install a 5 pinion rear planet and a viton input shaft/output shaft seal next winter. Maybe next winter has come in the middle of July.
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