Thread: ZF Flaring

My 300 tdi ZF is still flaring up to 2nd at 40kph,

I think from reading your post that you are perhaps not using the generally accepted terms here.
Flaring in an auto refers to a rise in revs after a gear change caused by slipping clutches.

If you are talking about the transmission sticking in first and not changing into second until 40Kph then that is not flaring but sticking in gear.

In a mechanical ZF this is usually ( always?) caused by a sticking governor which is at the back of the transmission, and there are many posts on this. It usually happens on the first gearchange of the day.

The cause I have read is that crap from dirty transmission oil causes this , and it and fixes other than a transmission rebuild rarely fix it.

Seeing otherwise the transmission works well , maybe live with it and change gears manually until it dies.
Regards Philip A

No, it shifts up from 2nd to 1st at 40kph at light to medium throttle when it shouldn't.

All other shifts are normal and good.

No, it shifts up from 2nd to 1st at 40kph at light to medium throttle when it shouldn't

I guess you mean that you feel that it should not change from 1st to 2nd as low as 40Kmh on light throttle?

I wonder if the auto is from a V8 as they are programmed to change early from 1st to 2nd as a fuel economy thing.

If you shorten the kickdown cable it should change higher.

If it is changing early it is more to do with the kickdown cable and the valve body than the governor.
I have reached the limit of my knowledge of valve bodies, but I speculate that the problem may be a broken spring in the valve body or that a V8 valve body is in the transmission.

Regards Philip A

Originally Posted by PhilipA

I guess you mean that you feel that it should not change from 1st to 2nd as low as 40Kmh on light throttle?

I wonder if the auto is from a V8 as they are programmed to change early from 1st to 2nd as a fuel economy thing.

If you shorten the kickdown cable it should change higher.

If it is changing early it is more to do with the kickdown cable and the valve body than the governor.
I have reached the limit of my knowledge of valve bodies, but I speculate that the problem may be a broken spring in the valve body or that a V8 valve body is in the transmission.

Regards Philip A

Regarding the bold bit above. I think my 300tdi has an array of holes for the kickdown cable meeting the throttle cable in the engine bay. Essentially kickdown adjustment.

Does yours have this Damien?

Sorry for the confusion. It's shifting down from 2nd to 1st at 40 kph, not up from 1st to 2nd. It then shifts normally through 2nd to 3rd.

Kickdown adjustment etc is fine.

You have got me.
I have never heard of that one before.
Maybe has something to do with oil pressure being insufficient .
Just a thought. Have you changed the filter when you changed fluid. If the O ring on the filter outlet was misplaced you would have very low oil pressure. They can fall out of position when replacing the filter.
Maybe talk to a ZF specialist.
Regards Philip A
I just remembered where I had experienced this before. I once drove a Commodore with Trimatic and it did the change back to second while driving along on light throttle at 50-60Kph. In that case it was low oil pressure, and basically a stuffed transmission.

If I read this correctly , change down from 2nd to 1st at full throttle at approx 45 kph, then revs away to get back to 2nd?? ie it kicks down to first then if you hold the throttle down it takes a while to change up again??. Regards. Ian Ashcroft

Hi Ian,

Yes, but not even full throttle. Will do it at 1/2 throttle also. It's also very consistent @ 40 kph.

It doesn't do it first change of the morning, and I can avoid it if I feather the throttle through 40 kph.

Damien