ZF 5HP18 Auto Transmission Problem

[ed007]

I have recently encountered something weird with my ZF 5HP18 transmission in the 98 M3. The transmission shifts fine most of the time. The only issue is with the 5th gear (overdrive). Under acceleration on the highway, sometimes the transmission will not go into 5th but get stuck in the 4th at higher rpm. To make it shift to 5th, I have to get off the accelerator and it eventually upshifts and then runs without problems. I also noticed that when it downshifts to 4th, the RPM's will jump to 3000 shortly and then go back to normal. If I keep holding the accelerator while in 4th at 50 mph or higher it will not shift into 5th.
If I run in M mode, I can shift without problems but have no way of testing the 5th as this one is not available in M mode.
This only happens when the car has been driven for 30 minutes or longer (warm).
The code that eventually comes up is P0735 - Gear 5 Incorrect Ratio.
I also changed the fluid but this did not solve the 5th gear issue. The tranny has 100,000 mi and never had any problems with it. This is the only code that pops up.
Anyone had anything similar and how to fix it?

[Rockdaddy]

I have a similar problem on my 2000 Z3. It shifts fine except won't go into overdrive at higher speed or lower speed for that matter. My M/A button has no effect. I posted last week and the only reply was from a commedian.

I just noticed the date on this thread. Did you get your trans issue resolved and what was the cause. Was it an expensive repair?

[MarkR540]

your tranny is probly on its way out.

[Rockdaddy]

It only has 35,000 miles? I sure hope not!!!

[fun2drive]

Have either of you guys disconnected the battery for 5 minutes and tried it again?
I wonder if this might be something that is learned?
My automatic transmission shifts pretty much as what you described except I do get into 5th gear without too much effort but not until I hit at least 45 mph or higher if I have more throttle.

[lilbnns]

my tranny doing the same thing, it gave me a speed sensor code, which i change.
i tried the battery diconnect to reprogram the computer but that no work. know i am left with checking the wire connection or do a rebuild or just swap it to manual

[ed007]

I am still driving with this problem, it has not gotten worse. You would think if it was mechanical problem it would have broken down by now after 1 year. I am thinking it could be speed sensor or temperature sensor issue but I did not change those out yet.
Does anyone have similar problem? How to solve it?

[ths916m3]

I have had the issue a couple of times....it is very intermittant. I have 161K miles on the transmission. It throws the transmission light and doesnt shift into 5th, but as soon as I turn the car off it works fine. Usually the only time I have ever noticed it was when it was raining. Its been like that for at least the last 2 years. I'm just waiting for my transmission to go out so I can swap in the 5 speed.

[fun2drive]

Both my M3's shift like this and I consider it normal since it learns your shift habits. I think when cold it will not shift out until you get a lot of rpms up. My E93 does the same thing, my wife's Avalon does the same thing.

If you back off the engine in 4th gear above 50 mph will it shift into 5th? If so normal function if not I don't know.

I bought Carsoft 8.2 for exactly this kind of issue. I can log real time data so I can see what is happening and why...

[ed007]

It is not really normal because the car used to have smooth shifts before. I still have the same problem, shifts fine when cold (first 10 minutes or so from start) and then starts slipping in 5th under acceleration. It upshifts into 5th only if I let go off the accelerator when in 4th gear and then locks in 5th. CEL shows up after a few slips and P0735 is logged. I don't have the cable for Carsoft software to monitor the systems more closely. It has been a year now and the transmission has not failed, not better or worse.
I did try everything: battery disconnect, computer reset (push in accelerator for 30 seconds or so and then press on the brake while stsrting the engine), cleared the code numerous times but still the same issue. After a few slips, it stops trying and just keeps going in 4th until the car is shut off and restarted.
I did notice it runs better in the winter under colder temperatures (fewer 5th gear slips).

[fun2drive]

In your 2 2009 post you said nothing about "slipping in 5th gear" but you do in this post. Was it slipping then too?
Slipping is not going to be fixed by anything you can do. You either need a rebuild or replacement because your have clutch plates not doing their job or insufficient pressure to keep them firmly attached to the steel discs.

There is a guy who has a transmission with I think 46K miles that wanted I think 350 bucks. I had planned to buy it but when mine fails I will just replace it with a 5 spd conversion.

First transmission in the M3 vert went well over 200k miles but again warm temps and lot of highway driving most likely the reason.

[onerepublic]

check fluids, sounds like a glocked Tranny filter

[Tony Soprano]

check the alternator, and batt. low voltage in the system can piss off the auto tcm. ive seen this on many auto bimmers. if its all good, then huh i dunno. as long as the trans goes through the gears normally with no slipping you should be ok.

if the trans light is going off and on have the codes checked, that will take the guess work right out of it.

[Wasiq]

Did anyone figure this problem out? Mine is doing the same thing, EXCEPT I have another issue. On the way home from school, the car downshifts from 5th to 4th and the transmission light comes on. It happens at the exact same location everytime, its a steep up hill and I'm doing around 50 and the speed falls to around 45 so the car downshifts and the light comes on. As far as upshifting goes, my car does the same exact thing, it won't go into 5th unless I let off the accelerator, this only happens at 45mph and above, if I'm doing like 47, it will stay in 4th, but if I let off the gas, it will shift into 5th. At 45mph or below, the car stays in 4th.

[lilbnns]

it the second time i hear sombody saying check the alternator. i remember mine problem started after i had change mine. its hesitates from 1st to 2nd gear then race from 3rd to 4th gear. what voltage should i be getting?

when going up hills drive in 3rd gear it stop the tranny from going in lamp mode.

[Frank87]

I am bumping this old thread as I may be able to add some useable information.

Car: 530iA V8 (M60B30 with 5HP18)

My problem:
Shift 4-5 in D when cold / medium temp, perfect
Shift 4-5 in D when warm and accelerating slowly = 50% chance it's bad
Shift 4-5 in d when warm and accelerating rapidly = perfect
Shift 4-5 in 4 (Move lever manually) when warm = perfect

When it "bad shifts" into 5, it does so by increasing RPMs, giving a noticeable "boom" and it will stay in 4. After that attempt to shift to 5, another attempt is made and the gearbox shifts perfectly into 5.

The strange thing is, that when it is cold / medium, it is always perfect. It is also perfect when I make it go to 5 myself by moving the lever from 4 to D.

Even more strange is that I have 2 5HP18 gearboxes that have this problem. One of them was the original box I had when I bought the car, that box now has 275.000 kilometres. The other box has 310.000 kilometres and is fitted right now. Other than the 4-5 problem, both boxes are perfect. The 310.000 box is better than the 275.000. When fitting the 310.000 box, premium ATF was used and a new converter was fitted as well. It has developed the 4-5 problem a few months after the fit. I have driven the wrecker where the box came from and it ran fine. Although possible, it does not seem likely that both boxes would fail with the same cause. Moreover, I can't find any decent explanations on the web on my 4-5 problem.

I do not think my friction material is bad. Here's why:
- If it slips under certain circumstances, it will always slip under those circumstances. However, under manual control, it never slips.
- I pulled 3 5HP18 boxes from 6 cylinder cars apart, learning material. All boxes had friction material left. Even a box (no work done on that box) with over 500.000 kilometres still had friction material left on the plates. Burning clutches and a slipping trans is possible but not on 2 boxes.. This sounds too coincidental.

In total, I have 3 adaptive 5HP18 boxes with the "088" box code for V8 E34 and E32. I am doing a full rebuild on box 3. I plan to mount it in 2 weeks. While rebuilding, the literature and experience taught me alot. Here's an interesting image:



When we go from 4 -> 5, we lose Clutch A & the brake band is applied.

No other moves are needed to do 4->5.

So if we have a bad shift from 4 -> 5 and we do NOT have a valve body issue, we have 2 options:
- The gearbox can no longer properly apply and release the brake band. This means we also have 1<->2 and 3<->4 problems. This can be caused by a worn out brakeband, damaged brake band tension mechanism or a leak in the route to the tension mechanism. Since my 1-2-3-4 are perfect and the band is applied on multiple occasions, I rule this one out.
- Clutch A does not disengage properly. This would mean that "something" is noticeable when we go from D / 4 / 3 / 2 to N / R. If we do not notice anything when we go to neutral or R, clutch A functions properly under those circumstances. This would mean that we are not dealing with a fluid leak.

Both of those parts are basically ruled out. The brake band functions properly at other shifts and so does clutch a.

I will have to take a look at the valve body. It never helps to open up your valve body after say 60k miles. I have rebuilt a valve body in the past and used it on one of the transmission that has the 4-5 problem. The transmission that is fitted right now, ALSO has that problem and I did not touch that valve body! So I don't think I screwed up on my valve body rebuild.

Should I find out what is going on here, I will let you know.

I do have to add that these boxes usually shift into 5 when you are done accelerating. That has always been the case for me on all my BMW's with the 5HP18.

[AJLM34A]

I found this when I was trying to find information on ZF 5hp18 valve bodies;

http://forum.roadfly.com/threads/131...aul-DIY-Part-1

I talked to Nat at Eriksson Industries and got my rebuild kit through him. He is very knowledgeable and might be able to help you.

[Frank87]

I already did a valve body succesfully. During that rebuild, I only replaced the regular parts from the main channel plate and the gasket.

I now ordered every single spring the valve body has. Original ZF parts. For some springs, an updated version was delivered so I guess ZF did some thinking about these valve bodies. Will see if I can fit a "spring-rebuilt" valve body next week.

[Frank87]

Update:

Bolted a rebuilt valve body under the car last saturday. I replaced all springs. Orifices and check balls were done a few weeks back.

The 4->5 shift spring I pulled from the valve body was bad. It was somewhat shorter than the new one and it was bent a few degrees.

The 4->5 shift is now perfect.





So:


Problem: Gearbox will sometimes do a bad 4->5 shift and stay in 4. After this bad shift, the gearbox immediately tries to go to 5 again and succeeds perfectly.

Solution: Replace valve body springs. Check the 4->5 shift spring in particular.

[scooper]

good work Frank!

[gerberauto]

Frank, this is an excellent analysis and follows the book, now I have an almost identical problem.
BMW 523 HP-18, BMW number: 1422 129. 1996 BMW 523i.
the difference is that mine shifts nicely all the way up to 5th gear, when I release the throttle and at the point when it should shift down to 4th gear I get a really big bang. all other gear are fine. Now I narrowed down problem and shifted the car manually 1-5 nice up shifts, but shifting down to 4th -big bang again.
So, its only when it supposed to shift down from 5th to 4th gear, no other downshifts are affected.
I followed your spring measurement and found that spring was to short too.
Can you please advise were to find the springs or a complete front upper valve body. Thats the small valve body mounted on the big valve body.
Any help would be appreciated,
Thanks,
Chris

[shogun]

A bit late, but in case you still need the 5HP18 parts, here some links
U.S. http://www.erikssonindustries.com/
or local:
ZF Philippines, Inc.
Km 23 Uding's Compound
West Service Road Brgy.Cupang
1771 Muntinlupa City
Phone: +63 2 808 9740 Fax: +63 2 838 2835 Homepage: www.zf.com/ph

[shogun]

ZF 5HP18 transmission fluid level check and change procedures, Drain and filler plug location. tightening torques https://www.thectsc.com//5hp18-trans...vel-procedures
5HP18 Transmission fluid level procedures

A) Transmissions Fluid Level Checking

1) The transmission fluid temperature must be between 30°C and 35°C before checking can begin. Use test equipment to determine the trans temperature.
2) The vehicle must be level with engine running at idle speed and air conditioning turned on.
3) Step on the brakes firmly, apply parking brake fully and shift to D and R, briefly pausing in each position before shifting back to the Park position.
4) With the engine running at idle speed and the selector in Park position, remove the filler plug. Monitor the transmission temperature, if a small stream of oil runs out at 40°C, the fluid level is correct.
5) If no oil runs out when the filler plug is removed, the fluid level is too low and oil needs to be added until it overflows.
6) With engine running, install the oil filler plug and tighten to proper torque.

B) Adding fluid after repairs

1) With the engine stopped and the transmission in Park position, remove the oil filler plug. Add transmission fluid until a small stream of oil runs out.
2) Insert the filler plug and tighten by hand. Start the engine.
3) With the engine running, remove the oil filler plug and add transmission fluid until a small stream of oil runs out. Insert the filler plug and tighten by hand.
4) Follow the “Transmission fluid level checking” procedure described in section A) above.

C) Notes on fluid level and adding procedure

1) Use ZF-LifeguardFluid5 - the Shell LA-2634 is no longer available.
2) If the transmission temperature rises above 50°C during the fluid level checking procedure the resulting oil level will be to low. Let the transmission cool down and repeat the fluid level procedure.
3) Have transmission fluid and a suitable oil pump available before starting the fluid level procedure. The transmission fluid temperature will rise quickly during the checking procedure.