700r4 lost 3rd gear
My 700R4 lost third gear on friday when I shifted at WOT. The trans was custom built 28,000miles ago to survive behind my 450HP small block. I was running it down Woodburn dragstrip when the failure occurred. The first time it engaged third, then went neutral. The second try, there was no third gear. I limped it home the 1.5 miles in second. Besides the 3-4 clutch pack that I understand is a weak link, what other parts might have failed to cause this? What other parts might need to be upgraded to prevent future failures. BTW, I upshift at 6,500rpm.
ASE Doc.. I moved your post to a new thread for answers to your problem and not confuse members with 2 questions in one thread.
Your loss of 3rd gear is as you suspect... the 3-4 clutch pack burned up is what I think happened.
Thatnks for your reply Crossley. My main concern is that this trans was built to withstand hard use behind my engine. I damaged third gear components twice and had to have the trans redone each time until they finally got it right and it held for 13 years. I want to take any and all steps available to be sure that this trans will hold up in the future.
I love my car and I try not to abuse her too much. Friday was her first trip to the dragstrip. I was so pleased with how she accelerated, then no third gear. Now I'm heartbroken that I broke her. I already spoke with the guy that built the trans before. He wants $1,500 to up date the unit with the latest hi strength parts. It's a good price but i just don't have it to spend right now. I'm a master mechanic but I specialize in engines and electronic controls. I have little experience with automatic transmissions. However, I've been studying and I think I can handle this okay. Plus, I need to get over my reluctance with these things and I hate having a part in my car that I didn't build myself. I worked with a great trans builder for 2 years and we did some hi HP 4L60s. I remember what was done to beef those up, like one sided clutches, 5 pinion planets and hardened reaction drum.
I just want to be sure I have this straight before I go into the unit. The upside is that the fluid still looks good so I don't think I smoked things too bad. The trans shifts perfectly withy its current valve body tuning. It is set up for auto/manual shifting and holds every gear to 6,800rpm. It also holds overdrive at full throttle above 80mph. Therefore, I don't need to worry too much about the valve body, beyond cleaning and checking. I will check out the pump, all bushings and thrust washers, and replace all seals. If there is anything else you can can think of, please let me know.
The Alto Red Eagles or better Raybestos Blue Plate Specials #RCPBP-04 handle abuse much better than the single sided Z-Pack 3-4 clutches.
Hi SS, thanks for responding. I have been doing alot of research and I have found that exact thing. The Red Eagles or Blue Plates with full thickness steels hold up better under heavy use. I know that the guys who built this trans in 1999 found some way to get 3rd gear to stay together. well enough that it lasted this long. I will find out what they did when I tear it down in the next few weeks.
In my research I have learned that there may be no lasting method for building the 3-4 clutch using the factory input drum. The backing plate just flexes way too much and under high pressure, the snap ring can pop out. Sonnax offers a redesigned part called the "Smart Tech" input drum that does away with the snap ring and flimsy backing plate, replacing it with a much more sturdy and flex free bolt on backing plate. The part sells for $500 so it's not a cheap fix but it seems like it will hold up alot longer. Have you checked out the PATC website? Also, how hard is it swap out the turbine shaft from one input drum to another? It seems like it might be tough. I never even considered it a possibility before. The Smart Tech comes without a turbine shaft.
The Smart Tech Drum is overkill for what you have.
The reinforcement kit would most likely do.
This includes a Hardened Input Shaft.
Chris >> www.CKPerformance.com
Dana >> https://www.700r4l60e.com/store/home.php?cat=19
A Hyd. Press is needed to swap the Input Shaft.
Thanks for the great information. That is a good price on the reinforced input drum with billet shaft. I'm still concerned though about taking out my 3-4 clutches. Obviously, you have experience with the units. Do you really think I can keep my 3-4 clutch together with the factory design? I know my power level isn't that high. I'm just worried about the high rev shift points. I plan on building another engine in the next few years that will make 600+HP. It will be a high rev engine too, likely peak power at 7,000. I'm afraid that I'll keep taking out 3rd gear every few years and I'd rather spend the extra$$ now to prevent that. I do however love the idea of saving $100s. Eventually, once I build the new motor, I know I'll need to completely redo the trans.
I figured it would take a hyd press to R&I the shaft. We have a 20ton at the shop but it is a pile and the frame has been sprung so that the ram is is crooked. If need be, I could have a good machinist do the swap for me. Of course, if I go with the drum and shaft from CK, I don't have to worry about that.
Another question: what is the real difference between split turbine shaft sealing rings and the solid white teflon rings? Is the solid ring really better than the split ring? The solid takes a special tool to install.
With that HP & RPM you'll need more upgrades.
Are you using the Hi-Rev 3-4 release springs?
May want to upgrade the Output Shaft aswell, 4L65E, Cryoed or Billet shaft.
You should talk with Dana about your goals/plans, parts you're thinking of using and see what He thinks will be needed. He specializes in the 700R4/4L60,60E,65E,70E.
These have detailed kit Info: 87-93 models; 82-86 kits also available.
675HP >> https://www.700r4l60e.com/store/prod...&cat=19&page=1
750HP >> https://www.700r4l60e.com/store/prod...&cat=19&page=1
Yes, PATC has a very nice site for parts.
700R4 Parts List at PATC Raptor Transmissions
I hadn't seen the single sided Red Eagles before now. I've also noticed many Builders using the Hi-Energy clutches.
The solid Teflon seals are much better when running higher pressures & handle heat better.
Some Info >> 700R4 Parts List at PATC Raptor Transmissions
You can use pieces of Mylar, Plastic bottle etc.. & Hose clamps to shrink/resize the Solid Teflon seals instead of buying the fancy tools.
The Low/Reverse tool is worth buying or making. About $30 on Evilbay.
Im not sure what went into the trans as it sits. I know that I had trouble with 3rd gear and the guys had to redo the trans three times over a one year period to make it hold up. I hate customers who pretend that they don't thrash on their cars and them blame the tech for repeated failures. I was dead honest with the people who built this trans. I took the lead guy for a ride to show him what kind of power I was making and how I want it to shift.
They built the trans to hold every gear to 6,500, hold 4th gear at full throttle, and to last without failure. I would imagine they had to install the rev kit. I'm also thinking about the rapid relief valve. I do sometimes down shift from 3rd to 2nd at higher speeds. I worry that I may have shortened the 3-4 clutch pack's life by dragging the clutches on this downshift. Maybe not. I would think that this would be evident by burning of the 2-4 band.
The plastic bottle material sounds like a great idea for installing the teflon no split rings. At this point, Im not thinking of a total overhaul but rather just fixing 3rd gear, correcting the crash shift into 2nd, and upgrading the 2-4 servos. The trans only has 28,000 miles on it and the fluid is not burned. If I tear the unit down and find things to be worse than I expected, I may have to rethink this. I plan to disassemble the pump and the forward clutches for inspection. I'll also look for any damage to the 2-4 band and replace that with the wide band and new drum if needed.
Im doing some side work this weekend for extra funds to go toward this project. The money was going to go towards extra payments on my new Snap On Solus Ultra scan tool(trying to pay it off as quick as possible to save on interest). Now, my priorities have changed. I'll put my Beasty on the lift Sunday and start pulling the trans. I'm going to take my time so may not have the trans torn down til next weekend. Then I'll make my parts list. I may have more questions at that point too.
Thank you very much for your help so far.
You're most likely correct about the Rev kit, I'm sure they did something.
On the 3-2 downshift, the 3/4 clutches disengage & the 2/4 Band, Forward & Overrun clutches are engaged. Engine/Compression braking is done by the Overrun clutches.
You can do a pressure check to get an idea of the Pump's condition, it may be fine.
I recommend the Alto Carbon 2/4 Band if you upgrade.
Is the 2nd gear crash/bang on the 1-2 upshift?
May be orifice in Sep. Plate too large or Accumulator problem.
I have a Billet Servo, can't remember if it's 2nd & 4th servos or just 1 servo. I got with some other parts I bought a while back. I'll send you a PM if I can find it, I honestly don't remember what I did with it. :spank:
Thanks again for your help.
I have a 400 psi gauge around here somewhere or I'll buy a new one. At one time or another I think I've owned every tool ever made. It's keeping track of the ones I don't use very much that's tricky. I plan on going into the pump to check for scoring or just wear of the cover and housing. I also want to be sure the vanes are all good. Then, once I know the pump is healthy, I'll swap in the high rev priming spring. I assume it's a 10 vane. Pretty sure the 13 vanes weren't around back then.
As far as the harsh 1-2 shift goes, I'm pretty sure the builder used the TransGo method of the time, which is removing the 1-2 accumulator spring and installing from 1 to 3 washers instead to set 1-2 shift "firmness". With high pump pressure this translates into a crash bang 1-2 shift at low speeds. PATC talks about this and they offer a heavy 1-2 accumulator spring which they claim will reduce the harshness. They recommend the Superior/Fairbanks servo to ensure solid band engagement. I've been looking at this servo and the Sonnax billet servo. They each have advantages and weren't available when this trans was built. My trans may have the Art Carr billet servo now. We talked about it when the trans was being built. If you come across the billet servo you have, I'll take a look at it. I like the idea of the wide carbonite band. I want to find the funds to include it, with a new reverse input shell, in this repair.
I'm waiting to see the damage in the trans to decide which way to go with the repair. If the damage is isolated to the 3-4 clutches. I'll focus on that and maybe upgrade the 2-4 band and address a few other little issues. I may go with the overkill Smart Drum just because it's a long term solution to the 3-4 clutch problem($500, ouch). I am worried about the process of swapping turbine shafts. It may be worth it to pay a machinist to do the job for me. I'm thinking that if a had an oven set up close by the press, I could heat the drum up and then the shaft would slide in much easier. I'm not sure if the locktight green would agree with the heat though.
Once I save up the funds, I'll swap in a hardened billet turbine shaft and be done with it. If the 3-4 snap ring has popped out, this will help me with that decision. Do you know where I can get a good input shaft(no drum), besides PATC where they want $534 for it.
You can put the Shaft in the freezer to shrink it & not heat the Drum as much.
CK Performance used to have 4340 or 300M Billet Input Shafts, not sure if He does anymore tho'.
You can check with Lonnie at Extreme Automatics. He may have them or know where to get one.
Extreme Automatics Where winning is easy
GM 700R4 / 4L60 TRANSMISSION INPUT SHAFT - BILLET 300M HARDENED STEEL | eBay
700R4/4L60E 300M INPUT SHAFT
Transmission shafts - High performance transmission - transmission
Have to make sure what Yr. model these fit.
So, I found an input shaft. Right there on PATC's website too. Just had to look for it a little. They have two choices, besides the $534 300M steel shaft. One is the factory 4L65E shaft at $59. It's heat treated from the factory and is stronger than the OE 700R4 piece. Then they have the 4L65E shaft that has been put through an additional hardening process for even higher torque capacity(580ftlbs). At $89, it's a pretty decent value. This saves me from having to reuse the factory input shaft with the Smart Tech drum.
Wow, The internet is such an awesome thing. 13 years ago when I tried to work on my own trans, there was almost no information available. There were books but unless you know where to look, it's hard to find good publications like ATSG offers. In 1999, when I first visited the idea of building a beefy 700R4, a local trans shop told me there was no way to beef up a 700R4 and that I should just go with a TH350 or 400. Glad I didn't take his advice.
Today, armed with the understanding that I have developed from alot of hours of research, I feel very confident in repairing this transmission.
4L65E shafts are different than 700R4 shafts, other parts would also need to be changed.
Mid Pg. >> 700R4, 700 Raptor Transmission from PATC, 700R4 4L60E 48RE 4L80E
Thanks for your reply. I see what you mean about the shafts being different. The links you gave me do show much better prices on the 300M shafts. They're still a little pricy though. I see though that GM released the heat treated shafts for the 4L65. They didn't release anything like that for the 700R4. Therefore, I may have no option but to use the 300M shaft if I want to install a hardened shaft. The turbine shaft that's in the trans now has obviously held up to the motor. What I'm thinking though is that I don't want to put the OE shaft in the Smart Tech drum, just to have to replace it later when I build a stronger motor. To use the 4L65E shaft, what other parts would need to be changed?
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