Lazy auto box

[mattwrigg]

Hi all

I'm knew to this forum and 928 ownership, having just bought a 928 S2 1985 from ebay for a bargain price.

Overall the car is in really good condition, but there are a couple of mechanical points that need sorting.

Firstly, the autobox is slow in changing from 3rd to 4th when in D (or when in 3, from 2nd to 3rd). It wasn't bad when I first collected the car (it has been off the road for a while), but now is pretty bad. It must be a second or so for it to change. Changing up in other gears is fine, from 1st to 2nd it is pretty much instant.

Could this just be oil levels in the autobox? I must admit I haven't checked yet.

Secondly, there is a slight hesitation under strong acceleration, then it picks its heels up. I'm unfamiliar with auto box mechanics, could this be something to do with the kickdown cable?

Many thanks
Matt

[Danglerb]

85 S2 would be a European spec 16v motor, and when it hits about 3500 rpm it goes.

Its best to assume nothing on a 928 new to you, have it checked over end to end, fix things starting with safety and PM issues and work your way down to minor stuff. If you start by fixing the most obvious problems you can find yourself thousands in with major work still ahead.

The 4 spd auto is a normal Mercedes Benz unit the same as some sedan of the same year uses, so anybody familiar with MB should do fine with it. I would start by replacing all the fluids and making sure the levels are OK.

[Pauwl]

Matt,

1st off, I've no clue how an auto box really works or why.
I've a '84 Euro S automatic, and this is my 'experience' - not backed up by any fact other than my own feeling of how the car drives.

pulling away: If you want to move fast from start, shift the gear to '2', and floor it, shift up as required. I believe only when in '2' and floored does it actually pul away in 1st gear, otherwise it leaves first gear alone, and always pulls away in second.

Acceleration. Some others will undoubtably explain the difference between Wide Open Throttle and the kick-down switch. Blast it to the floor & it will change back down a gear if possible.... Yeah right. Frequently it doesn't, or it has a lag before it does.

Here's the strange part about it. I've driven mine hard(er) lately, flooring it more often, and it seems to 'learn' (although I have been told the '84 can't learn like later models can). It now shifts down when I 'blip' the gas sufficiently for it to know I'm not slowly accelerating, but am overtaking or doing some other manoeuvre that I need more acceleration on tap.

The kick-down hasn't changed. Sometimes it just doesn't. This is frequently I think when I don't really floor it fast, just push the pedal all the way down, then some.

If I want to 'force' a shift to 4th gear, I do a 'reverse-blip', lifting my foot from the accelerator for a 1/2 second, then putting it back where it was. Somehow it changes up a gear then.

In short, your car seems to work like mine, my oil level are OK, just checked last week.

Advice: warm it up, then floor it often, and 'teach' it. Remember: this is not backed up by science at all. YMMV.

Of course, you now have a reason to floor it frequently

p.s. with WOT, it still drops a gear while doing 140km/h, so even at relative speeds, the 'blip' results in a VERY nice pull.

p.p.s. sometimes gear changes are silky-smooth, when going downhill, sometimes it seems a small delay then 'tug' happens.

hope this is all somewhat clear.

Pauwl

[mattwrigg]

Thanks both for the replies. I have had an 80's Merc 300 4 speed auto, which is likely the same box?, so I have got used to the blips, it does take some doing getting used to them.

It would be nice if there was someone local who knows these cars to have a drive and tell me what it's really like. As usual I didn't test drive any before I bought this one, I bought it by accident really!

Pauwl, maybe you're the one learning, not the car!

Matt

[mattwrigg]

by the way, mine definitely pulls off in 1st when in 3, you can count the changes, then it changes again when moved into D.

[mattwrigg]

by the way 2, does anyone have experience with Swepco? I've been recommended it by a 944 owner.

[Danglerb]

Originally Posted by mattwrigg

It would be nice if there was someone local who knows these cars to have a drive and tell me what it's really like.

Matt, gotta tell us what area you live in first.

What works for a lot of people is to put info into a signature with rough location and year and model of your car.

[ROG100]

Well done on getting an auto. They are far superior to the cronic 5 speed. Worst manual box in existance IMOO and I have afew of them.
Check your fluid level with care and it probably needs a change as well as the filter.
Kick down switch needs checking to make sure the pedal is actuating the switch - in most cases they are not.
Check the cable for slack as well.
Once you get it in perfect shape you will no longer call it slow and those stick guys will wonder why they wasted there time 8>)
No stick has ever beaten a comparable auto.
I know I have tried most.
The best is the early 3 speeds they rock and eat the early 5 speeds for breakfast.

[mattwrigg]

Hi again

I'm from Yorkshire in the UK, forgot to mention that!

Change up from 1st to 2nd is very quick, I just wish the other changes were as good. i'm assuming that wear is the factor for slow changes, the car has got 165k miles on it.

ROG100: is the kickdown cable easy to adjust for slack then?

[Danglerb]

Old fluid, wrong level is more likely.

[ROG100]

Hi Matt,
I used to live in Hull.
Roger

[mattwrigg]

Roger,

I take it the move to the US was a step up then?

I'm going to try and get some Swepco as I've heard good reports.

Matt

[Pauwl]

Matt,

I'm over in France. If your shark wants to cross the channel at any time, give me a shout and we can 'test' our automatics on the 'private closed roads' of France.

[jthwan22]

My car is doing the exact same thing. I found this on Rennlist http://forums.rennlist.com/rennforums/showthread.php?t=258342&referrerid=58392
I got the K1 spring but did not install it yet. The spring info is on: http://forums.rennlist.com/rennforums/showthread.php?t=288715&referrerid=58392