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I've browsed 250 threads via search here and have not seen this exact problem. The closest one I saw involved not being able to shift into 1st or reverse, and then occasionally other gears. My problem involves only reverse.
I've owned my C4 for several months. Shifting has never been a problem, and was not a problem until recently. It will shift into 1st through 6th just fine. The clutch does not slip at all. Shifting into reverse became difficult (more effort required) the last time I drove it, and tonight it would not go into reverse at all. It is the same with the engine running or off.
My car has about 155K miles, and the PO detailed records show a dealer replaced the transmission, TO bearing, clutch disk, and plate at 76K miles. The clutch MC was replaced at a dealer at 141K miles. I don't see a note where the slave was ever replaced.
Any advice or experience is welcome, thanks in advance.
I found this recall bulletin while searching the web. My VIN is in range, but since the original transmission was replaced, I wonder if this would still be a problem? The symptoms are identical.
UPDATE
From Bill at ZF Doc:
If the replacement transmission part number is 1052 000 089, the detent ball roller it has/had in it is already of the correct design. This campaign was intended to replace older version detent ball rollers that do not have a flat spot with a one that does have a flat spot. There were 4 revisions to this part of which the flat spot came in after 2nd revision. The flat spot allows oil to flow around the detent ball roller equalizing any hydraulic back-pressure during operation.
Both parts had the flat spot, so the repair was unnecessary.
Last edited by C5_Shopper; 08-23-2014 at 01:00 PM.
The part still seems to be available from GM which is certainly a plus and with symptoms being identical I'd say it's certainly the next logical move. There should be a tag on the right side of the transmission with the transmission assembly information. I'd confirm that is a proper part number and move forward. I'd expect to see this number on the tag:
1052-000-089
Is there a reman tag on the transmission below the data tag?
I've seen the TSB but never a car with the problem. If your car fits the VIN sequence and it's not been performed then a GM dealer should still show it as an "open" recall if the VIN is queried.
I don't know how much information was included in this data base released for the consumer but it might be interesting to try your VIN.
I've never used the request but might later to see if maybe the older information is there.
With the transmission replacement one could assume maybe that the repair could maybe be "debated" but it might be worth the ask. The recall is by VIN and if still shown as "open" and there's no "reman" tag on the transmission ... who knows.
The part still seems to be available from GM which is certainly a plus and with symptoms being identical I'd say it's certainly the next logical move. There should be a tag on the right side of the transmission with the transmission assembly information. I'd confirm that is a proper part number and move forward. I'd expect to see this number on the tag:
1052-000-089
Is there a reman tag on the transmission below the data tag?
I've seen the TSB but never a car with the problem. If your car fits the VIN sequence and it's not been performed then a GM dealer should still show it as an "open" recall if the VIN is queried.
I don't know how much information was included in this data base released for the consumer but it might be interesting to try your VIN.
I've never used the request but might later to see if maybe the older information is there.
With the transmission replacement one could assume maybe that the repair could maybe be "debated" but it might be worth the ask. The recall is by VIN and if still shown as "open" and there's no "reman" tag on the transmission ... who knows.
Thanks for the reply. There are no recalls listed when I put in my VIN.
I lifted the car and looked at the transmission. There is an aluminum manufacturer tag on the passenger side, I see no other tags. It has various data on it:
ZF Industries Inc.
Made in USA (odd, I thought these were made in Germany )
Model: S6-40
Parts list No.: 1052 000 089GM (basically correct per your info)
Serial #5xxxx
Customer spec. no.: 12455189
Total ratio: 2.64-0.49
None of the other fields are stamped, such as speedo ratio, oil capacity, n=, oil grade.
The transmission was replaced by a Chevy dealer in Ohio circa 2003 (prior owner), I'm in Florida, so I doubt anyone will want to help me if that is the case.
It looks like the detent replacement may not be too bad of a job, but I have another question:
I'm familiar with the T56 that's in my Trans Am and some other cars I've built, the ZF is of course different. There appears to be a method to enable reverse in order to avoid accidentally shifting into reverse when going from 5th to 6th. As I recall, on the T56 it is a lockout solenoid. I have a 1995 specific C4 shop manual, and it shows a rod in the shifter that functions as a reverse lockout (the manual calls it #25 "Reverse lockout rod"). I read a thread here that mentions one being broken. There is no button on my shifter, and I can't move the shifter up or down when trying to go into reverse, so if I have this rod, I don't know how it is actuated.
How exactly is reverse enabled in a 1995 model car?
I know little things like the detent can cause problems. My "other" Chevy is a Corvair, and I had an oil pressure relief valve stick one time on a rebuilt engine & it blew the filter out.
In '95 the detent for reverse was changed and the "lift-ring" removed from the shifter. Yours is what's called a "crash-thru" and there's no changes that you can make. There's no solenoid devices used in the ZF, the only safety you have is the clutch operated safety for "crank".
Have a dealer run your VIN if it fits the sequence. See what that mentions, if it shows none at the dealer and it fits the sequence numbers then it's considered to have been performed at some point. Regardless of age on the dealer query if it's got a campaign that's not completed it will show as such.
The part looks inexpensive enough, it's available and the install looks to be pretty straight forward.
Your ZF is a US assembled product - that's not an error. Not all ZF's were German builds.
In '95 the detent for reverse was changed and the "lift-ring" removed from the shifter. Yours is what's called a "crash-thru" and there's no changes that you can make. There's no solenoid devices used in the ZF, the only safety you have is the clutch operated safety for "crank".
Have a dealer run your VIN if it fits the sequence. See what that mentions, if it shows none at the dealer and it fits the sequence numbers then it's considered to have been performed at some point. Regardless of age on the dealer query if it's got a campaign that's not completed it will show as such.
The part looks inexpensive enough, it's available and the install looks to be pretty straight forward.
Your ZF is a US assembled product - that's not an error. Not all ZF's were German builds.
It's definitely not going into reverse at all. I found the detent for $26 shipped, so I'll give that a try. After reading some threads here I will refill it with Amsoil.
It's definitely not going into reverse at all. I found the detent for $26 shipped, so I'll give that a try. After reading some threads here I will refill it with Amsoil.
Post back with the reports on the fix. A snapshot or two might be good also. I would likely have done the part "local"!
Will do, pics will be tough due to the plug's location next to the CAGS solenoid. I've found that local dealers charge a lot more and rarely have parts for my older cars. Plus the closest GM dealer is a 40 mile round trip. Since I'm not in a hurry and got free shipping, it was a good deal for me.
The good news is the new part arrived and was easy to reinstall. There was no big difference in the OD of the new & old parts, perhaps .002". Looking them over, I don't see how oil can be kept from getting behind them as there is a flat spot on the detent roller, it's not perfectly round.
The bad news is it still will not shift into reverse at all.
My next idea is to pull the shift **** (another great design with the wedge holding it in place ) and see if there is a rod in the shifter and if it has broken off as I had read about in another thread. Since my transmission was replaced in 2003, it may have had a mixture of parts.
Update-
Drilled & tapped the wedge for a 5mm thread and was able to remove it. What a great idea for serviceability. The shifter is solid, so no rod. I suppose the next idea is to check for a screw as noted in the other thread. If I have an early model transmission with a late shifter would this possibly cause the problem? Seems unlikely to me since it went into reverse with no problem for a long time.
Any other ideas are welcome.
Last edited by C5_Shopper; 08-21-2014 at 04:23 PM.
I let the Amsoil soak in for a while and tried again. I can intermittently literally "crash through" when the clutch pedal is about halfway up if I keep pressure on the shifter, it will pop into reverse. This is the engagement point for the clutch for the forward gears, so it does not appear to be a limited slave cylinder travel issue.
I pulled the lower shifter boot and can see the mechanism. There does not appear to be any block (#27) as depicted in the other thread, I've inserted the parts schematic below. I can see the large shifter rod (#48) moving back & forth as I shift 1-6, and it clearly is not moving as far forward in reverse as it is in 2nd, 4th, and 6th.
More reading & thinking, the detent function (pushing the lever into the reverse gate) seems to work fine, so I don't think this is an issue. Accessing the reverse detent would require transmission removal. I browsed a few more threads:
I'm going to try the clutch diagnosis listed there and see how it looks.
Copied and edited for convenience, source is the ZF Doc website:
LEAK DOWN TEST OF THE CLUTCH MASTER AND SLAVE HYDRAULIC CYLINDER
How to check out the operational condition of the hydraulic clutch system-
A. Leak down test for the master cylinder:
1. Thoroughly bleed the system with Valvoline Dot 3 Dot 4 Full-Synthetic brake fluid.
2. Simulate the vehicle being parked on an incline for 12-24 hours with the front end at least 1 foot higher than the rear.
3. Lower the vehicle if raised for test. Note: Do not cycle (pump) the clutch before next step.
4. With the clutch pedal remaining depressed, start the vehicle.
5. Try to put it into reverse when it first gets started (cold).
Note: Difficulty getting into reverse when in this condition indicates that the clutch master cylinder is not at 100%.
B. Leak down test for the slave cylinder:
1. Repeat steps 1-5 of this procedure except with rear end raised.
Last edited by C5_Shopper; 08-22-2014 at 08:24 AM.
Leakdown tests failed, am ordering Dorman replacement master & slave from Rock Auto for $99 shipped. Hose looks good, so I'm reusing it, will flush it out first. I lost the clip for the pushrod when removing the master. It is PN 3817880, and sells for $1.76 shipped on eBay.
Parts should be here next week. I'll update if this solves the problem.
I hate to have to say this but did you verify that they hydraulics that you purchased were good? There have been many instances of people going through several before they get a good one. With that said, unless there was a pretty severe event dealing with reverse (like someone engaging reverse while going down the highway) I would not be inclined to write the transmission off. There is a system inside the transmission that uses ***** and a slug that prevents it from engaging more than one gear at a time. I have never seen any issues with it but it may be an issue with that.
As much as it sucks I would go through and verify that they hydraulics are in fact good, then I would try and run the car for a while and see if it would loosen up going into reverse. If the hydraulics are good, what do you have to loose at this point? I hope it works out for you; if I was closer I would come take a look at it for you.
I have no pedal play at all. I don't run this card hard, so there has been no missed shifts or accidental shifts into reverse. It shifted into reverse fine until a few weeks ago. The clutch grabs about like it did before- almost halfway up on pedal travel.
What's telling to me is I can't get it into reverse with the engine off. It goes into 1-6 OK engine off or on. Bill at ZF doc said it is likely that the reverse gear stiff entry and now refusal is a reverse synchronizer specific related issue.
I may run the car on the highway as long as I don't have to back it up anywhere and see if this makes it any different. Seems like an internal bind at this point.
Last edited by C5_Shopper; 08-30-2014 at 05:17 PM.
Does it shift into reverse normally when the engine is not running?
If it shifts fine with the engine off, but not on I would guess there is an issue with the clutch hydraulics.
What's telling to me is I can't get it into reverse with the engine off. It goes into 1-6 OK engine off or on. Bill at ZF doc said it is likely that the reverse gear stiff entry and now refusal is a reverse synchronizer specific related issue...
Originally Posted by chevyowner
Does it shift into reverse normally when the engine is not running?
If it shifts fine with the engine off, but not on I would guess there is an issue with the clutch hydraulics.
08-13-2014, 09:46 PM
1995 C4/ZF6: Can't shift into reverse
)
) and see if there is a rod in the shifter and if it has broken off as I had read about in another thread. Since my transmission was replaced in 2003, it may have had a mixture of parts.
