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Question about torsion bar delete
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Munky  



Joined: 13 Jan 2016
Posts: 25
Location: Minnesnowta USA

PostPosted: Mon Jan 25, 2016 2:12 am    Post subject: Question about torsion bar delete Reply with quote

Please take a deep deep breath and remember I'm a noob to 924s

Thanks

Now if you are still there and willing to give me some advice please

I've had VW bugs since I was 17 (in my late 40s now) and sold my last big boy VWs last year (a 66 912 and a VW 356 kit with IRS) so I've lived with torsion bar pain and TBH not a great fan.

I've seen some of the informed suppliers of 924 parts (that it seems safe to Trust their advice and products) sell torsion bar delete kits. Are these safe? I wouldn't do it on any of my former VWs as two miles down the road I would expect the rear end to be dragging and the shocks punched through.

Is this really plausible and safe on a 924?

I've also read that the torsion bar delete works on the 'S' as it has 944 suspension. How plausible is it to swap out the 944 pre 85.5 suspension into an early 924 and do a torsion bar delete?

Are there areas of the chassis that would need strengthening? Is it a plug and play kind of thing? As I don't have a 924 yet, I'm not sure how the rear suspension mounts with shocks and can't seem to find any comparison pictures between the 924S set up and the standard 924 that seem to answer the question.

Thanks
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nickthompson  



Joined: 26 Mar 2013
Posts: 863
Location: Central Georgia

PostPosted: Mon Jan 25, 2016 3:12 am    Post subject: Reply with quote

Early 944 and 924s have the same suspension. The difference being the 944 has four wheel disk brakes.
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Munky  



Joined: 13 Jan 2016
Posts: 25
Location: Minnesnowta USA

PostPosted: Mon Jan 25, 2016 3:20 am    Post subject: Reply with quote

Thanks Nick

So then the torsion bar delete should work for both.

I wonder if there is a difference to the shell/chassis mounting points on the later cars? Thicker or more boxed in?
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ideola  



Joined: 01 Oct 2004
Posts: 15511
Location: Woodstock IL

PostPosted: Mon Jan 25, 2016 4:20 am    Post subject: Reply with quote

Have you done a search? There are numerous threads on this topic.

What year car are you trying to modify?

The upper strut mounts are not reinforced and you risk breaking them if you rely solely upon them to hold the car up with coilovers. Conflicting opinions and reports on this topic. Some say they've gone years with track duty with no ill effects, others have demonstrated broken upper strut mounts.

Switching over to a 944 setup with alu arms that can support the many aftermarket coilover TB delete setups is not trivial, requires replacing the entire torsion carrier assembly for reasons I don't have time to enumerate at this moment. I've done this on multiple cars, and have come to the conclusion that it is not worth the effort except on a maximum effort car. For future projects I will just upgrade to stiffer torsion bars and call it good. Willing to discuss further when I have more time...
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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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Munky  



Joined: 13 Jan 2016
Posts: 25
Location: Minnesnowta USA

PostPosted: Mon Jan 25, 2016 5:43 am    Post subject: Reply with quote

Thanks ideola

I've really appreciated and read a lot of your other posts.

I'm currently trying to understand what car I should buy with my various desires and goals in mind.

There are a few interesting cars locally to us including a stock 78 924, a martini edition car (needing love) and a couple of 'S' cars. The later 2.5 S cars seem to be a better proposition but they all seem to be black and almost double the purchase price! There is also an SE here in the twin cities but seems a little OTT from a cost / work required standpoint. (It's not as good as the BAT SE and more expensive but it's local).

I'm looking at the torsion bar delete so that I can quickly change the ride height from an aesthetics stand point more than anything. Adjustable spring plates may work, but I think might be a little too limiting. I've just had enough of playing with splines trying to get the sides the same after they have settled. I guess I'm just getting old and want to only have to do it once.

I'd be interested in your thoughts if you do have time. Thanks
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Fifty50Plus  



Joined: 28 Feb 2008
Posts: 1013
Location: Washington DC area

PostPosted: Mon Jan 25, 2016 6:22 am    Post subject: Reply with quote

Coil overs certainly have more ride height adjustability and are easier to make spring weight changes. However, 924 and 944s have adjustments for balancing corner weights on the rear trailing arms (unlike 356s, 912s early 911s and probably most VWs). Dr F. Porsche chose torsion bars (unwound springs) for lower CG and reduced unsprung weight on all of these cars (VW first). None of these cars have enough rear structural support at the top shock attachment point to carry the full load of the car without reinforcement if the Tbars are swapped out for coil springs.
While indexing the torsion bar is a bit of a pain at first when going heavier, it's doable and doesn't require welding. I've built and raced both types of rear suspensions and like both for different reasons.
_________________
1979 924 NA race car
1982 924 NA race car - Sold
1982 924 Turbo almost a PoS
1981 924 Turbo a real PoS, new engine
1982 924 Turbo nice body, blown engine
1972 911 E race car - going to Vintage
Various 944s to become IT-S race car
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Munky  



Joined: 13 Jan 2016
Posts: 25
Location: Minnesnowta USA

PostPosted: Mon Jan 25, 2016 7:24 am    Post subject: Reply with quote

Thanks Fifty50.

The reason for the slew of questions is as I mentioned before, it's kind of worrying from what I know from my VW days but then I see products like this on Paragon

http://www.paragon-products.com/30-Series-Race-Rear-Coil-Over-Kit-p/koni_30-series-rear_kit.htm

That seems to show that it's okay on a 924S which is why I'm trying to understand the difference between the 924S and the standard 924. I have to admit to being surprised, but as ideola has mentioned some say they have even tracked their car with this set up.

Perhaps if i do go to the trouble of this route, I could fab up a new weld in subframe. I think that's what they do to make VW bug air ride compatible - but they have the advantage of being able to take the body off the pan to do it.

I've seen a couple of nice early cars for sale, but it seems more and more like the 'S' is the closest to what I am looking for.
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ideola  



Joined: 01 Oct 2004
Posts: 15511
Location: Woodstock IL

PostPosted: Mon Jan 25, 2016 2:03 pm    Post subject: Reply with quote

In my opinion, the best bang for the buck is either the best S1 931 you can find/afford, or the best 1988 924S you can find/afford. If not for the 88 924S SE, I would be looking for one of the less common colors like the dark garnet red, the dark blue, or silver in the 924S.

Many S1 931 and most 2.0L NA 924 came with 4-lug. These are a cinch to swap over to five lug sourced from a donor 924S, which is the easiest way to get the coilover-compatible alloy trailing arms. You can mess around with 944 stuff, but then you have to deal with late offset hubs on an early car, and it just gets more complicated to ensure you have the right bits. So take the easy route and source your donor suspension from a 924S. You then have the flexibility to do t-bar delete (if you're daring), heavier t-bar, or leave the stock t-bars in and add coilover helpers at the rear (what I did on the club sport).

Re-indexing the t-bars in not really that hard. If you're going to swap in a five lug, you'll want to do the whole torsion carrier anyway, which is the opportune time to mess with the t-bars. To do coil overs in the rear, you have to do the whole torsion carrier anyway because the the spring plates are different on the alu vs. steel trailing arms, and there aren't many (if any) coil over options for steel trailing arm cars on this side of the Atlantic. So basically, if you want coil overs, guess what, you're going to be swapping out the entire torsion carrier (because the spring plates are different between steel vs. alloy trailing arms).

Getting the alloy trailing arms now opens up all of the 944 coil over kits for you.

Reindexing the bars is not that hard. I do this with the torsion carrier on the ground. I get the one side where I want it, then do the other side. Flip the carrier over (on a known flat surface), and if both "banana" wing mounts touch the ground, both sides are equal. If not, just redo the second side again until you get it right. I've done this four or five times now and have always been able to get it within the first couple of tries. Not really that big of a deal. Rasta Monsta has some measurements posted that will also help you determine exactly where you want the ride height; but if you're going to add helper coil overs, you don't have to get the t-bar perfect because you can then raise the height with the coil overs. You do have to be mindful to an extent on pre-load, but if the t-bars are "close enough", you can dial everything in with the coilovers + the built in +/- half inch of adjustment on the t-bar eccentric.

All of that said, as I said earlier, unless I were building a maximum effort racecar where corner weighting and preload were absolutely critical, I wouldn't even bother with the coilovers. More expense and more work to do than just dealing with the t-bars.

A couple of other notes:
Most of the coil overs I've dealt with require some modifications to the upper shock mount because the upper spring perches of most of these setups won't clear the "boxed" section on the early cars. I don't know if the upper shock mount is different on later cars, but you will have to grind away some of the metal on the "boxed" section in order to prevent the upper spring perch from binding. Details are in my club sport project thread.

On a 1980 S1 931, the snailshell trans mounts to two arms that attach to the torsion carrier, so if you opt for an S1 931, you will need to transfer the trailing arms, spring plates, and t-bars from your donor car to the G31 torsion carrier. On ANY other 924 or 931, you can simply swap the entire donor torsion carrier assembly into the recipient chassis UNLESS you have an early 77-78 car. For those cars, there is no option for bolt on because the torsion carrier mounts to the chassis differently. It can be done but it requires some fabrication, the details of which I've never been able to pin down, but have read about in a couple of threads here.

Sorry, this is a bit of a ramble, I probably ought to write it down more succinctly. Take a look at my threads on performance improvements (stickied at the top of this sub-forum, look for the suspension sub-section), and look for the my thread on "illustrated guide to 5-lug conversion" in the how-to sub-forum as these have more details and options to consider.
_________________
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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Munky  



Joined: 13 Jan 2016
Posts: 25
Location: Minnesnowta USA

PostPosted: Mon Jan 25, 2016 3:20 pm    Post subject: Reply with quote

Thank you so much for taking the time to type all of that up. It has really been exceptionally helpful and insightful.

I would never have thought of reindexing the splines off the car like that as I'm so used to the pain of VW based systems.

I need to reread your comments again to let them all sink in but I'm sure that this is going to have a great bearing on the car I choose.

I just wish I could find a reasonably priced 'S' in something other than black that isn't an auto. I guess I just need to keep looking until something comes up. From the sounds of it, the Martini car probably isn't the one for me, as it being a '77 will be more work than it's worth. Which is a shame as I really like the idea of the edition.

Again, thank you for taking the time to put your reply together. Very much appreciated.
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fiat22turbo  



Joined: 18 Jan 2006
Posts: 4040
Location: Portland, OR

PostPosted: Mon Jan 25, 2016 3:41 pm    Post subject: Reply with quote

http://www.944spec.com/944SPEC/technical-articles/42-torsion-bar-re-indexing

http://www.clarks-garage.com/shop-manual/susp-06.htm

http://www.944spec.com/944SPEC/technical-articles/61-suspension-history

http://www.clarks-garage.com/shop-manual/susp-15.htm

It's really not hard to do with proper measurements.

I did it myself after getting help from Rasta Monsta and others on the board, got it right on the first try. Setting the torsion bar carrier on a set of sawhorses helps quite a bit when I was installing the 28mm torsion bars from CIP1.com.
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)
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Munky  



Joined: 13 Jan 2016
Posts: 25
Location: Minnesnowta USA

PostPosted: Tue Jan 26, 2016 2:28 pm    Post subject: Reply with quote

Wow - there's some reading!

Thanks for taking the time to find all of the pages and for posting the links. I think my next few lunchtimes at work are going to be filled.

I'm starting to think the splines adjustment on a 924 is no where near as frustrating as my old VWs.

Thanks all
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Fifty50Plus  



Joined: 28 Feb 2008
Posts: 1013
Location: Washington DC area

PostPosted: Tue Jan 26, 2016 3:53 pm    Post subject: Reply with quote

With the adjusters on the trailing arms, you are golden (easier than VWs).
If you follow Rasta and Stefan's guidelines, you are platinum.
_________________
1979 924 NA race car
1982 924 NA race car - Sold
1982 924 Turbo almost a PoS
1981 924 Turbo a real PoS, new engine
1982 924 Turbo nice body, blown engine
1972 911 E race car - going to Vintage
Various 944s to become IT-S race car
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Munky  



Joined: 13 Jan 2016
Posts: 25
Location: Minnesnowta USA

PostPosted: Wed Jan 27, 2016 2:18 pm    Post subject: Reply with quote

Fifty50Plus wrote:
With the adjusters on the trailing arms, you are golden (easier than VWs).
If you follow Rasta and Stefan's guidelines, you are platinum.


Thanks
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gla924sem  



Joined: 08 Nov 2002
Posts: 405
Location: Taylor, Michigan

PostPosted: Fri Feb 12, 2016 5:52 am    Post subject: 924 Reply with quote

It's been several years since I owned my 924 race car
I opted to delete the torsion bars and go with coil overs since it was allowed in PCA Club Racing SP2
Did a lot of research and a friend from PCNA got me in contact with someone who raced 924's in Europe
Per that contact......in order to delete the TB's and go with CO's the upper shock mount must be reinforced
Not a hard job.......had a local shop do it for me........around $1500 when I had it done
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 1603
Location: Somerset, UK

PostPosted: Fri Feb 12, 2016 6:55 am    Post subject: Reply with quote

Most 924/944/968 race cars in the UK still run torsion bars with the coilovers. Weight loss appears to be the only reason to lose the torsion bars. With a hole cut in the sills its relatively easy to knock out the torsion bars to adjust. Seen it done track side with a lump hammer and bar by a race team
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1980 931 - forged pistons, Piper cam, CGT turbo, 951 ducted FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife LSD
Now www.924board.org/viewtopic.php?t=34690
Then www.924board.org/viewtopic.php?t=31252
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