Gemmer steering box

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doublegarage
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Dino: Fiat Dino 2.4 Coupe
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Gemmer steering box

Post by doublegarage » Mon Jan 27, 2020 3:53 am

I had my 2400 Coupe raised today and decided to look into the "notchy" steering I had felt on the last drive. Turning the steering wheel there was a definite "detent" just right of center - and and another bad one to the right of that. Further away from center it felt much better.

Therefore Idisconnected the pitman-arm from the steering linkages to see how that felt and that was much worse, the mass of all the linkages etc mitigated the notches. It kind of felt like the 2 x UJs in the steering column were phased badly or something - therefore I lowered the column, removed the intermediate column with its UJs so now I can feel he raw input shaft of the steering box and...oh man, it felt really bad.

So I took the box out and put it in the vice. Pretty bad, 2 seriously bad notches/detents. But at least now I can get to the adjuster on top (it's under a sheetmetal join inside the wheelarch and hard to get at on the car). Backing off the adjuster and the notches feel much better - then tightening to just remove all play at the center and it doesn't feel great (rougher at center and slight notches, smooth at each end) but better.

It's almost as though it's tightened up over time. I've owned the car since 2011 and never touched the top adjuster. The box is full of clean looking oil and no sign of leaks at the bottom.

How to proceed? I don't know of anybody who can rebuild these or supply new parts - does anybody know? Plus I don't believe other Fiat boxes (eg 132, 125 etc) fit or have interchangeable parts. I think adjusting the box "looser" will improve the steering feel, but really I think the box needs more drastic action.

Any ideas welcome, thanks,

-Richard

Dinoswede
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Re: Gemmer steering box

Post by Dinoswede » Mon Jan 27, 2020 3:05 pm

Having overhauled a Gemmer/Dino steering box last year, I can confirm it is hard finding parts for it.
The worm-shaft bearing "ball-cages" and the oil sealings are availible, but that´s it.

Concerning the corresponding "bearing outer rings", I have some indications Gemmer actually changed
dimensions slightly during the production run.
The steering box I overhauled, had different outer diameters for these two bearing outer rings -
47,3 mm and 46,2 mm. The casing was stamped "10/66" so I guess this example was a very early
one.
In the Spare parts Catalogue, page D2.02, only one of these rings is shown - no 9917590 - but I
never found it, so I had the corresponding Fiat 238 spare part no 9917603 grinded down to correct
measurements.
Unfortunately, it seems the worm-shaft bearings often are in bad shape, and need to be replaced.
If so, you will feel it when turning the worm-shaft by hand - it is often binding, or shows signs of side-
or end-play.
All steering boxes of the worm-and-roller type share the same main problem - the contact surfaces
at the worm-shaft and the roller slowly wears, so the adjustment possibilities slowly disappear.

Below a simple graphic illustration over the problem. By time, a "crater" develops in the centre
position, and if adjusting that, you will get a growing binding effect just "outside" this position, in
both directions.
IMG_4141.JPG
IMG_4046.JPG
IMG_4035.JPG
IMG_4036.JPG

Dinoswede
Last edited by Dinoswede on Wed Apr 29, 2020 4:58 pm, edited 1 time in total.

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doublegarage
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Re: Gemmer steering box

Post by doublegarage » Mon Jan 27, 2020 8:18 pm

Great pictures and explanation, that's really helpful, thanks.

It does feel as though somebody tightened it to adjust for play at the "notch", so made it stick in the notch, like your drawing suggests.

I guess now I have it on the bench, I should open it and see what I find - replace the things that are actually replaceable and see if that improves it.

-Richard

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doublegarage
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Re: Gemmer steering box

Post by doublegarage » Tue Jan 28, 2020 6:29 am

I've searched the forum and see others posting pictures of Fiat 132 steering boxes - showing that they have different chassis mounting points in the main casing, therefore unsuitable - but does anybody know whether their main worm/roller parts are interchangeable?

Also - I see that Mr Fiat is advertising the service of "complete rebuild" for about $1,500 - just wondering whether anybody has used that service and whether it's truly a "complete" rebuild or just "replace all the parts we stock", which would be fair enough but a little expensive. I plan to contact them and will report back here, but just wondering if anybody had tried this already.

Thanks,

-Richard

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doublegarage
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Re: Gemmer steering box

Post by doublegarage » Fri Jan 31, 2020 3:59 am

I decided that, seeing as I have the steering box out of the car, I should replace the parts that are available (bearings and seals). First job is of course to remove the Pitman arm and..

..the Pitman-arm will NOT come off. I've tried:
3-arm puller
Pitman arm puller
hitting with BFH + above
heating (a lot) with MapGas blowtorch
Impact wrench on Pitman arm puller

But it won't move. The last thing to try will be to borrow a friend's oxy-acetylene rig for yet more heat. Needless to say, I expect the lower seal is already toast so it has to come off now. If the extra heat doesn't work then I'll cut it off.

Therefore - does anybody have a spare Pitman arm, or does anybody have a spare steering box, to sell me?

Thanks,

-Richard

Stefan2000
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Re: Gemmer steering box

Post by Stefan2000 » Fri Jan 31, 2020 6:04 am

I can't help you with a pitman arm.
But i've done the same thing on these Gemmer boxes as well, they are also used on Lancia's from that time.
The way i managed to get it off was by using a big hydraulic press. You need to fabricate something with plates that will shove in between the pitman arm and the housing. And then you need a LOT of force. I was astound how much force was needed and trying it with a puller and a torch won't even get you close of getting it off.
And with a lot of force i mean a lot of force, like 50 Tons or some crazy number. When it comes loose it's like a bomb explosion 8-)
Maybe you have some workshop or machine-shop around that can try to do it for you?

Georg
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Re: Gemmer steering box

Post by Georg » Fri Jan 31, 2020 8:19 am

Hi Richard,
I have experienced a pitman arm not coming off easily last year. However, finally I have been successful by soaking with a rust remover for some days, then using a pitman arm puller, oxy-acetylene flame and a heavy hammer.
Screw the pit arm puller on and tighten it very much. Yes, heat it a lot, until you see it glowing. And hit strongly on the side of the arm. Not on the shaft. Mine came off this way.
Good luck.
Georg

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doublegarage
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Re: Gemmer steering box

Post by doublegarage » Sat Feb 01, 2020 1:28 am

Hi Stefan and Georg

Thanks for the ideas there - I do have a 10ton shop press (not 50!) so I will see if I can support it in the right way and press on the end of the shaft.

And Georg yes, good ideas, in other words, do all the things I have tried so far (except oxy-acetylene) but do them all simultaneously!

I'll report progress. And if anyone sees this and has an arm or steering box to sell me, please reply.

Thanks,

-Richard

Fanalone
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Re: Gemmer steering box

Post by Fanalone » Mon Feb 03, 2020 6:24 pm

BC5222

Dinoswede
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Re: Gemmer steering box

Post by Dinoswede » Mon Feb 03, 2020 11:48 pm

Answering Fanalone:

Both yes and no!
When looking at the Spare parts Catalogue page D2.02, DINOPARTS.de actually
has used wrong Fiat numbers in their parts list:
The LOWER bearing "outer race" is number 9917590, not 9916359 - which are
the two corresponding "ball-cages". It is said to measure 47 mm in outer diameter.

Probably it will fit most Dino/Gemmer steering boxes, but in the (probably) very
early steering box I overhauled recently, the lower bearing "outer race" had a
47,3 mm outer diameter! In that case, 47,0 mm would not work at all...

The HIGHER bearing "outer race" is not shown anywhere in the Spare parts Catalogues,
so it has never got a FIAT spare parts number!
I measured the outer diameter being 46,2 mm, but I am sure, the claimed 46,17 mm
outer diameter is spot on!
I wonder why Gemmer choose such odd bearing dimensions - standard bearing sizes
would have helped us a lot!

Dinoswede

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