30/12/2009

How to fit a short shift kit to a Porsche 944

THE WHY?

It has to be said that the 944 doesn't have the lightest gear shift you'll ever come across. So it makes sense to keep this part working as efficiently as possible. There are several ways this can be achieved. The first and by far the simplest is to make sure the transmission oil has been refreshed (A  job that only takes an hour, but can make your drive feel 100 times better). The second and third options involve replacing the shifter mechanism at either the gear stick end or the transmission end. Over time you'll find that wear and tear take their toll and the shift will not be as precise or as smooth as it should.

Since I had the transmission off the car and had noticed quite a bit of play in the plastic ball joint on the linkage I decided to replace it with and after market short shift kit.


THE TASK

This job is far easier if the transmission is off the car, however it is still do-able with it still attached. You'll need:

Socket set and/or ring spanners
Short shift kit (Bought mine off ebay, but you can also buy a really nice one from here)
Hammer

and maybe....

Hex rod and two rose joints (see foot of post)
Hacksaw (see foot of post)
Thread tapping set (see foot of post)



THE HOW TO

(Amateur mechanic Job Time approx: 1.5 hours (off the car) or 2+ hours (on the car)

Firstly identify the original shifter linkage and support arm attached to the gear box. If your transmission is still attached to the car the linkage sits on top of the transmission. You'll also need to slide back the rubber boot and undo the bolt that connects the linkage to the shift rod that runs through the car before you can continue.


Now remove the black rubber boot completely by sliding it off the linkage rod (you'll need to re-attach this to the new linkage later).

Next undo the nut and bolt at the top of the linkage where it joins the support arm. At this point the bolt on mine sheered as it was so old and rusted. If the same happens to you then you can either buy a replacement from Porsche or make you're own alternative support arm using some hex-rod and a couple of rose joints (See end of post for details on this).

Assuming you've not had problems undoing this nut and bolt you can then proceed to remove the small bolt that fastens the linkage to the shifting stub on the side of the transmission (Note: the flat side of the shifting stub that the bolt presses against). Having removed the bolt a small tap to the side of the linkage with a hammer should remove it from the stub and the transmission completely leaving only the support arm attached to the transmission at one end.

Here is a photo of the new linkage (left) beside the old one (right).



Installation of the new short shift linkage is the reversal of removal, taking care to line up the flat side of the shift stub as you slide on the linkage and do up the bolt. Then reconnect the support arm to the linkage and finally slide the rubber boot back on.

Here's what the finished article should look like.



Now for those of you that are interested in the support arm (The orange rod in the picture above). Having researched the short shift kit on the web before I attempted this modification there are several manufacturers all offering roughly the same piece of kit at varying prices. Some of the short shift kits come with a support arm similar to the one I made and some (like the one I went for) just make you use the original arm (and had the bolt not sheered then I would have reused the arm).

To make the arm you will need to source a length of hex-tube / hex-rod. In the UK this is easier said than done as most hardware stores don't stock it. Fortunately because I have been going Karting since the age of sixteen I happen to know that hex rods are used as the steering track arms on these vehicles. So a quick search on ebay for 'Kart track rods' brings up a number of results right away and at some very reasonable prices. The good news about buying them off ebay is that they usually come with the rose joints already attached at either end. If they don't then you'll need 1 x 8mm Left Hand Thread rose joint & 1 x 8mm Right Hand Thread rose joint (They are also known as 'track rod ends').

If you've bought your Kart track rod then you'll instantly notice that it has an 8mm thread cut into it at each end, one will be a left handed thread and the other will be right handed (Right handed threads are standard on virtually every screw you've ever come across). We need to make the rod shorter which means cutting off one of the ends. Leave the left hand threaded rose joint attached to the track rod and measure it up against the original support arm. Mark the length and use a hacksaw to cut off the standard right hand threaded end (we don't need this bit). You will now be left with left handed threaded length  and will need to re-tap an 8mm right hand thread into the sawn end. Once this is done attach the right handed rose joint and you'll have an adjustable support arm. By simply using a spanner to turn the rod you'll notice it'll pull the rose joints inwards and by turning the other way it will push them outwards.

Simply attach it in place of the original support arm using a couple of 8mm Allen bolts and some washers as shown in the photo above (Using Allen bolts instead of normal hexagonal bolts allows the rose joints to move more freely).

14 comments:

  1. Good job!!!Looks nice.How is it on the car?how is shifting?how much shorter?

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  2. I've got used to the difference as have been using it for over a year now, but the main big difference is between 1st and 2nd, I reckon it reduces the shift movement by between 35-50%

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  3. Just thinking of doing this on my S2. As the plastic cross head bush is completely worn out.

    Just wondering if I still need to purchase a replacement bush if I fit one of these kits?

    Thanks!
    Nick

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  4. When you say cross head bush, do you mean the big white plastic piece in the centre of the first picture?

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  5. Just seen your post on the Porsche Club forum which makes things a little clearer. If you're buying the short shift kit then you won't need the plastic cross head bush you mention.

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  6. ok, well I've received the kit and just about got everything off but the last step where you remove the bolt and slide the linkage off the stub is nearly impossible. Its might as well be welded on! Ive tried tapping (beating) it with a hammer, prying it with a crowbar, and heating it with a blowtorch and it just will not come off!

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  7. Yep, mine sheared off when I tried to undo mine. The only thing you can do is leave some penetrating oil on it overnight or get some heat on it and then try to undo it.

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  8. Great write up Dave, going to change my linkages soon using this guide. Was just wondering why you decided to go for the short shift linkage kit over the standard OEM kit? Won't making the shifts shorter mean you have to apply more force to change gear which will make the changes even heavier than the standard linkage?

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  9. I went for the short shift kit because the engineering of the pivot looked superior to the OEM Porsche part. I figured that if Porsche were to redesign that part today then they would probably come up with something like the short shift kit solution.

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  10. And to answer your second point, the old linkage on mine was so worn that anything I replaced it with would have been an improvement. The shifts are probably only slightly heavier with the short shift kit but that I feel that is compensated for by the noticeable reduction in gear shift length, especially between 1st and 2nd where it is most noticeable. One other thing to point out now that the short shift has been on my car for a while you need to make sure you keep the rose joints and main pivot well greased (say every service), as it appears the British weather likes to wash off the grease and it will get noticeably stiffer. It only takes five mins to nip under the back of the car, no jack needed and with a blob of grease on your finger just to rub it over the joints. Hope that helps too.

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  11. Hi Dave,
    I am in the process of fitting a short shifter to my 944S2 and would like to know which holes in the shifter you used and the difference each hole makes ie top hole or bottom hole and what difference the length of the hex bar makes to the gear change ? Is it that it moves the gear lever to the driver more ? and the two holes does the bottom hole make for a even shorter shift. I just want to improve the gear change a bit not using it for racing . Any comments would be useful .

    Thanks
    delboys2


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    1. There was only one large hole in the kit I fitted to mine so I just clamped it up as tight as I could with a couple of washers either side so the nut and bolt heads wouldn't destroy the hole. Are the holes one above the other or side-by-side?

      The hex bar I set to exactly the same length as the original piece of metal that was on the original Porsche shift mechanism. I don't think there's any benefit in adjusting this otherwise the gear stick won't sit upright when in neutral.

      The forwards/backwards motion of the stick is reduced automatically by the difference in length (see picture 2 comparison) of the bar that clamps to the transmission shift post.

      Hope that helps and please correct me if anyone has better logic?

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  12. Dave ,thanks very much for your comments ,the short shift I have has the two holes or rather slots, are one above the other. I think the lower one is for even shorter throw?. Sorry to ask questions only had to wait ages for the part to arrive and then they sent instructions in german , I do dutch but not german. Nice blog with good instructions. Owned my '91 S2 for 13 years and have spent a lot of time and money getting it in top condition.


    Thanks very much

    Delboy

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    Replies
    1. I would agree, but it might make the shift heavier than it already is. Depends how supple your transmission is I guess. Thanks for the kind words about the site, glad to be of help.

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