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track upgrades question
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MikesCoupeGT  



Joined: 18 Oct 2006
Posts: 439
Location: Ontario Canada

PostPosted: Wed May 03, 2017 11:14 pm    Post subject: track upgrades question Reply with quote

I have a few questions.

My 924 is a lot of fun, and I know that it will not be the fastest car out on the track. However after watching the PRDA from Britain, I see that with some tweaking these cars can be faster than Boxsters.

So if I wanted to increase my torsion bar, what would be a good size to go with? How hard is this to do? I don't think it should be too hard but just want to gauge this out.

Secondly; I know the best way to get better braking is to go with the 944 suspension, but is there any other way to improve the braking on the 924. Such as upgrading the rear drums to a disc brake from BMW; Ford Etc....?

Thanks guys. My Watkins Glen weekend is coming up on the May 19th, - 20th weekend. I may be taking a MINI Cooper S in place of the 924 while I look at these upgrades.

Cheers;
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ideola  



Joined: 01 Oct 2004
Posts: 15499
Location: Woodstock IL

PostPosted: Wed May 03, 2017 11:23 pm    Post subject: Reply with quote

My recommendation would be to bite the bullet and just go to five-lug / four wheel disc. That would be the opportune time to also change out the torsion bars for something stiffer. If you plan to dual purpose the car (street and track) then you probably don't want to go much stiffer than 30mm for the torsion bars.

Upgrading to four wheel disc will make a massive improvement for track performance because you won't have to keep adjusting the rears. I would also recommend getting a brake booster and master cylinder from one of the later cars so that you can run a front rear split rather than the X split on the early cars. These changes combined with good rubber and aggressive pads will probably allow you to outbrake most things you'll come up against.
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15 981 GTS | 88 924S SE | 82 931 Holbert | 82 931 Rallye | 81 937 | 81 Euro 931 | 81 Weissach | 80 US 928 | 80 US 931 '941' | 80 US 931 | 80 931 GTR | 79 Sebring | 78 D-Prod Replica | 78 w/D-Prod kit | 78 Poli-Form | 78 Limited Edition | 77 Martini
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morghen  



Joined: 21 Jan 2005
Posts: 7832
Location: Romania

PostPosted: Wed May 03, 2017 11:24 pm    Post subject: Reply with quote

I bet there are bolt on-ish vented disks for the fronts and also stuff for the rears to be converted to disks...I think European Fords and Peugeots have 4x108 bolt patterns...I kind of remember somebody doing a Peogeot rear disk and hub swap on the 924 to get disks.

Also if you keep the rear drums, as far as I know the later models have the self adjusting system...if not...I'm sure it can be transplanted from more modern VWs and Audis.

I'm no track expert but you can always try the 951 or 968 sway bars...I use them on one of my cars and it drives very very flat around corners.
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CÚdric  



Joined: 27 Aug 2004
Posts: 1717
Location: Sweden

PostPosted: Thu May 04, 2017 12:35 am    Post subject: Reply with quote

I have a lot of hours on track with both na and turbo cars.

If you already have konis or similar, suspension wise I would go with(it is what I have now:)):

28mm torsion bars from cip1.com

Coil over conversion of the front struts, super cheap, :
https://www.rallydesign.co.uk/product_info.php?cPath=2243_2244&products_id=3458&osCsid=gbmhijfa99jipk6v6t800ueic5

+350Lbs/inch springs up front.


If everything is stock atm I would go with a complete GAZ setup with spring rates matching the above.


I assume you already have track tyres and maxed out camber up front?



If you have the money go for full weltmeister adjustable sway bars, easily the best buy for my 931 yet. Everytime you do a change in spring rate, tyres, camber etc you can always dial in perfect balance.




Regarding brakes, what is your setup now?

When I had an N/a I ran Hawk HP+at front, stock rears and RBF600 fluid + stell braided lines. That setup never faded, worked well for 12h endurance aswell. Pads lasted a loong time aswell. Adding breake cooling ducting is of course a way to get even better pad life.

You wont have shorter brake distance with 5lug, but the brake pedal feel and not having to constantly adjust the drums might well be worth it. I now run Hawk HP+ on my 931 with great success.
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MikesCoupeGT  



Joined: 18 Oct 2006
Posts: 439
Location: Ontario Canada

PostPosted: Thu May 04, 2017 3:15 am    Post subject: Reply with quote

Honestly Cedric. I don`t think I have changed the camber on the front of the car. As for track tires I am running Dunlop Direzza`s. They are getting close to the end of their life.

At the moment the car really does run fantastically. I just want to be able to really turn it up a notch. Espcially while I am working on getting the 944 going.

The rear drum brakes I have known to be a weak point of the 924. My car also sits low in the back, which is why I was thinking of upgrading the torsion bar. Probably due for a change. I do have some thicker sway bars on the floor of my shop. I think I`ll measure them tonight and see what I have.

Thanks everyone for chipping in and the support. I need to stop watching the 924 racers that you can see on YouTube. the PDRA group just shows what we have always known. These cars are great.
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ideola  



Joined: 01 Oct 2004
Posts: 15499
Location: Woodstock IL

PostPosted: Thu May 04, 2017 3:29 am    Post subject: Reply with quote

One other thing I'll add in here...if you are thinking of going with thicker sway bars, be aware that there are three different mounting arrangements at the front:

1. Early 924: with main sway bushings captured in a saddle on the sway bar, and LONG drop links that connect to the sway bar end and a tab on the steel A-arm.

2. Late-run early 924 / early-run 944.1 and 924S: with main sway bushings attached via an L-bracket that fastens to captive nuts on the frame spar, and the ends mounted directly to the a-arm.

3. Late-offset 944.2 and beyond: use the same L-bracket arrangement as above for main sway bars, but have a short drop link that attaches directly to the alu A-arm.

My guess is that you have option 1, which if you stay with it, will limit your choice of sway bar size. If you want any of the later / thicker sway bars, you can abandon the saddle mount for the main sway bushing, and use Nut-serts to attach the L-bracket to the frame spar; and then you will need the correct A-arm (or to modify your existing A-arm) to accept the mounting style of the sway bar end that you choose.

Note on nut serts: I have done this on the Club Sport. It seems to work fine despite warnings that they would be ripped out. Granted, I haven't driven on the track, but I have about 2000+ miles of very spirited driving with no sign of issues. If you're not comfortable with nut-serts, you could weld bolts or studs onto the frame spar and use locking nuts to secure the L-bracket, which might be more suitable for track usage.
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ideola  



Joined: 01 Oct 2004
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PostPosted: Thu May 04, 2017 3:38 am    Post subject: Reply with quote

Sway Bar config 1:


Sway Bar config 2:


Sway Bar config 3:

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MikesCoupeGT  



Joined: 18 Oct 2006
Posts: 439
Location: Ontario Canada

PostPosted: Thu May 04, 2017 4:23 am    Post subject: Reply with quote

Ideola;

I do have the early car, 1976. To that end. I don`t think it even has a rear sway bar. So I would need to check my Haynes manual and see if there is a place to mount one. That could help as well. No rear sway bar but a smallish stock bar.

Regards;
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ideola  



Joined: 01 Oct 2004
Posts: 15499
Location: Woodstock IL

PostPosted: Thu May 04, 2017 4:33 am    Post subject: Reply with quote

http://www.924board.org/viewtopic.php?t=21794

The early cars have a different torsion carrier, so not even sure if those instructions can be adapted to your car, but it's worth a look. I have a pile of 14mm rear bars, let me know if you need one. I also have a wide variety of front bars in both early and late styles. 23mm front with 14mm rear is standard setup on the 931, and should make a big difference for you.
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 1551
Location: Somerset, UK

PostPosted: Thu May 04, 2017 4:49 am    Post subject: Reply with quote

Ideally you want a matched front and rear spring rate for suspension, sway bars and a level ride height. Geo and tyres are equally important if not more important. View the chassis as a whole not individual components. One upgrade affects all others. Stock brakes should be adequate for a lightened track whore. The uk racers are using stock brakes but with stickier pads and racing fluid. Also Gaz coilovers are employed in most cars. Cars are circa 900kgs which when well driven can rival poorly driven Boxsters.
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924-76  



Joined: 05 Jun 2006
Posts: 1355
Location: Ontario, Canada

PostPosted: Thu May 04, 2017 8:49 am    Post subject: Reply with quote

As far as I know the previous owner of your car is still living in the same city then you and I know for a fact that he offered you to help at multiple occasions.
Since he know this car in and out as he rebuild it from the ground up, I bet he would be able to help you and he may have some spare parts as he still own a 931 and he's still involved in the community.
If only I could remember his name or had his contact info...
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MikeJinCO  



Joined: 08 Jun 2010
Posts: 716
Location: Maysville, Colorado

PostPosted: Thu May 04, 2017 3:29 pm    Post subject: Reply with quote

If you want to put a rear sway bar on an early car, you'll either have to weld the sway bar brackets to the TB carrier or use big muffler clamps to bolt one on. I bought the muffler clamps, something like 5" for big diesel exhaust and still have them around as I went the welded route. You have to weld the 944 brackets to the clamp bracket I believe. This installation can be done without removing the TB carrier.

I got the weld brackets from Sunset Porsche, they were not very expensive at the time, it is quick and easy job when the TB carrier is out, I'm not a good enough welder to do it overhead from under the car with the TB carrier in place. I put on sway bars from a 944T(24F, 18R) and at HPDE school last year my instructor, a Formula Ford driver, was impressed with the handling. On my track car under construction I'll have a 30m Hollow from the M030 968 front and a 22mm adjustable Welt rear which may be too much for the front-we'll see-- sometime.
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CÚdric  



Joined: 27 Aug 2004
Posts: 1717
Location: Sweden

PostPosted: Thu May 04, 2017 6:41 pm    Post subject: Reply with quote

I have a friend with a ┤76, wonderful car to drive. On his car we went for a slightly softer setup, its also much lighter than my 931.

250Lb/inch coil over conversion (as my earlier post) or weltmeister 250lbs (they need to be cut though to get the right lenght, wont affect spring rates due to their design)

25.5mm torsion bars from 968


He first ran stock sway setup (with early 18mm rear), then later bought the 28/22 weltmeister setup. With the exhaust clamp method mentiond above.

Of course it also has maxed out camber up front, which really gives a great front end bite. Its perfectly balanced and can easily rotate with throttle lift, such a nice car to drive!
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924RACR  



Joined: 29 Jul 2001
Posts: 8099
Location: Royal Oak, MI, USA

PostPosted: Thu May 04, 2017 11:05 pm    Post subject: Reply with quote

I'd go as stiff as you think you might possibly want on the torsion bars - because it's a massive PITA, you don't want to have to face doing it twice. I did.

All the rest of the posts cover the options well I think, don't need me to re-hash.
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chris79  



Joined: 29 Jan 2014
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Location: milan

PostPosted: Fri May 05, 2017 1:53 am    Post subject: Reply with quote

I installed 931 swaybars first version, they are to me first necessary improvement for track driving.
With standard na setup in the corners you have to drive at 45░ 😁
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