Historic Forest Stage Rally 124 Spider

Non-engine, eg: aerodynamics, gearboxes, brakes, suspension
Post Reply
Simon
Posts: 145
Joined: Sat Aug 01, 2009 6:55 pm
Location: Leicester
Contact:

Re: Historic Forest Stage Rally 124 Spider

Post by Simon » Wed Aug 14, 2013 8:38 am

Hi Phil,

I'll drop you a PM this evening rather than clutter up Nigel's thread, but yes, the vented kit is a Whoa! It's the caliper mounting brackets that are missing and you would need to get pads too. You'll find a picture of the kit in this thread (the brackets were from the unvented kit and now on the car) http://guy-croft.com/viewtopic.php?f=5&t=2141

Simon.
GC_15

PumaPhil
Posts: 71
Joined: Mon Apr 22, 2013 5:18 pm
Location: Lincolnshire, UK
Contact:

Re: Historic Forest Stage Rally 124 Spider

Post by PumaPhil » Wed Aug 14, 2013 9:08 am

Hello Simon,

First of all I'd like to tell you that I am in awe of the work you have done to create the Arbath replica; stunning work. Your's was one of the first threads I looked at when I joined the GC forum and made me realise what a professional bunch of people there are out there! I will post some pictures soon of my 124 which looks OK until you lift the bonnet but a new GC engine will, I am sure, make me very eager to show off what's under the lid when it's done!

Many thanks for your offer but I had also sent an email to Jon at Midwest 124 and he replied that Whoa! Brakes are currently unavailable because the cost of machining the custom brackets has tripled and all supplies of the discs have dried up over there too. So as you are also missing the brackets I'm wondering if I should look at the Fiat 500 brake conversion offered by Allison's Automotive? I value your opinion on what CoA I should follow but please remember my car will be for road use only so I don't think I need the very best brakes but certainly more powerful ones that will be safe, reliable and have good 'feel'. Also, I've read some of the threads regarding brakes and, although much of it was very technical regarding not having too much of a front-rear bias imbalance, I was wondering if X-19 rear calipers would be OK for my rears? The problem I have is, although they have been refurbished, the parking brake function is still inoperative. I think the X-19 option would be far cheaper option than getting them refurbished again - but from a company that knows about 124 brakes this time!

In the meanwhile, I will ask Jon at Midwest 124 if it is at least possible to get the brackets made up as I guess the Whoa! option remains be the best for me.

thank you, Phil
GC-05
'If you think experts are expensive, you should try amateurs!'

A redline run my GC's engine: https://www.youtube.com/watch?v=80nEhsJbH2w

Guy Croft
Site Admin
Posts: 5004
Joined: Sun Jun 18, 2006 9:31 am
Location: Lincoln, UK
Contact:

Re: Historic Forest Stage Rally 124 Spider

Post by Guy Croft » Wed Aug 14, 2013 10:37 am

Whoa - that is very bad news about Whoa...


Jonny - if you're reading this get it sorted!!

Mark Allison's brakes? If they are as good as his Computronix ignition they will be fantastic!

G
Guy Croft, owner

Sandro
Posts: 38
Joined: Wed Aug 30, 2006 12:30 pm
Location: Chester
Contact:

Re: Historic Forest Stage Rally 124 Spider

Post by Sandro » Wed Aug 14, 2013 2:02 pm

Hi all,

I am in the process of converting my spider to have Uno Turbo brakes to fit under 13 inch Abarth original alloys. The conversion is easy , except the bracket to mount the caliper carrier. The company I used in Germany took 4 months to even attempt to start mine then refused due to issues with their machine shop but I do have the drawings for these brackes now if that helps anyone. I used the brackets that were originally form the argenta but they were for 256mm diameter discs, the uno turbo I believe are 240mm diameter to the locating holes need to be moved 8mm so the pad sits fully on the disc. Once I have thenm back I will post pictures

I have found also a rack and pinion crossmember in the US and i have made the strengthening mods recommended by the various forums i have read. I will post pictures when i get it back for all to see.

regards

sandro
GC_33

Guy Croft
Site Admin
Posts: 5004
Joined: Sun Jun 18, 2006 9:31 am
Location: Lincoln, UK
Contact:

Re: Historic Forest Stage Rally 124 Spider

Post by Guy Croft » Wed Aug 14, 2013 2:59 pm

I want to know if the Uno Turbo is as good at stopping ie: as EFFECTIVE as Mark's conversion please!

I also want to hear about calliper styles for each conversion and suitability for master cylinders. Mark is expert on his own brakes and has written elsewhere on this, search by Allison will find it.

Please make posts technically complete and accurate. There is almost as much junk written about brake conversions as engines. If you want cutting edge proof read Ian Nixon's Lada and Miro's 131 threads - where 'everything else proved 'useless' and in the end total solution was a 'must-have'.

Braking is FAR TOO SERIOUS A SUBJECT to be dealt with in a hit-and-miss way. ESPECIALLY for someone who has never done this before.

Thank you.

GC
Guy Croft, owner

TomLouwrier
Posts: 331
Joined: Wed Jul 28, 2010 3:09 pm
Location: Leiden, The Netherlands
Contact:

Re: Historic Forest Stage Rally 124 Spider

Post by TomLouwrier » Thu Aug 15, 2013 8:09 pm

hi guys,

OK, here's my views on the subject. Feel free to bash them ;-)
Anyone who actually did these conversions, please follow up as Guy asks.


OEM and the bolt on upgrades

Uno Turbo
Personally I've never seen this one in real life. Miro reported some time ago about the Uno turbo conversion (viewtopic.php?f=14&t=1901) as a bolt on modification. (Miro, are you reading??).
Performance-wise the gains are small: you'll have the same caliper (48mm) and MBC (19mm) pistons. The front disc will be 240mm over the 227mm standard set you'll find in nearly all Fiats from the 60's and 70's, so you'll get 240/227= 106%. Nice, but not exactly shocking. It is my belief that most who do this conversion in fact feel the difference between their old, ineffective brakes and the rebuilt, well greased and properly sliding ones.
Main improvement is that the discs are vented, so you'll keep the brakes cooler for longer. A big plus when you're doing track days or going for rally fun in the mountains.
You can run this with the original rear brakes and MBC without upsetting F/R balance and pedal travel / force.
I've given up on this option because the parts are made of unobtainium and the gains not worth the effort.

124 DS and Volumex
The late 124 Spiders got their front brakes from the Argenta which used the standard 80's Fiat setup: 54mm caliper piston on a 257mm disc. This combo gives an improvement of about 44% over the 48mm/227mm. Cars got a lot heavier in those days because of safety and comfort requirements.
With this they fitted an enlarged rear caliper on the original disc: 38mm on 227mm non-vented (was: 34mm).
You'll find that in true Fiat-partsbin-style these rear calipers were lifted off the 125 and you can still get them as replacement parts for the FSO Polski. They were also used on the Monte I think.
(By the way: all this tallies nicely with the things I said earlier about F/R ratios: 65+/35- for North-South drive lines and 55/45 for mid engined cars.)
These 38mm rears should be a bolt on, but the construction is still the 1st generation sliding caliper with exposed wedges so it'll be prone to sticking and needs good regular maintenance.
As far as I know these models had a slightly larger MBC and booster (possibly from an Alfa 164 or Fiat Croma) to compensate for pedal travel and force, which fits the calcs.


Aftermarket kits

Whoa / Wilwood
The Whoa-kit looks neatly executed, it's based on a Wilwood caliper.
I have looked at their site and catalogues and no doubt Wilwood makes good products.
However.
The calipers in the Whoa don't feature dust/water shields. They will have no OEM references and certainly no E-markings (Euro type-rating). This makes them unsuitable for use on the public roads. You will have a car that is illegal to drive and thus not insured. That is two major problems in one sentence.
Wilwood themselves make disclaimers about their products being for track / racing / off road use only and I've not seen one reference to high way use. Get into an accident, even one that has nothing to do with any brake failure at all, and you will be in very big trouble.
Another aspect is availability of the pads, especially outside the USA.

Allison / Fiat OEM
The Allison kit is based around the brakes from the current Fiat 500 range. Parts / pads will be available easily. The calipers are designed and tested for years of regular every day use and abuse. With big firms like Fiat and its OEM suppliers (Lucas, Bosch, Valeo) you can be very sure there's a lot of development and testing done on the parts.
I have suggested to Mark he redesigns his caliper carrier (adapter) to fit a vented 240mm disc as found on the Uno Turbo and some younger Fiat models (Palio, Siena). This is not a difficult mod and it would make his set work under original 13" wheels too.



Now if you plan on using your car for track use only, this about sums it up. You make your choice, pay at the counter and fit your new kit. Everyone expects you to understand and handle all aspects of modifying a vital safety system on your car. If not, you are supposed to employ someone who does.
And since this is a racing forum, we could rightfully end the discussion here.

Most of us however, including the anonymous readers, either have a 'fast road' or a rally car. Most rallies demand that the participating cars are fully road legal and registered. So everyone in this section of the audience gets to deal with:

The law
In order to get modified brakes officially accepted, you have to have them examined and approved for use on your road going car.
In Germany and The Netherlands it is possible to have individual modifications inspected and accepted. You will have to convince the inspecting body that your modifications are both well engineered and properly executed, so get your dossier up to scratch (drawings, calculations) and invest time and money in good fabrication of parts. The use of OEM (Fiat) parts will help you show the inspector / inspecting body that your car will be at least as safe as it would be if it had come from Turin this way.
In France it is nearly impossible to get anything changed on a car unless you get official paperwork from the factory that they endorse the modification and in fact support it as one of their own constructions. This goes for engines, brakes, suspension.... Bonne chance, mes amis!

Getting your car past a regular check (MoT, TuV, APK, CT... whatever) is not enough. I've heard enough silly people claiming the modification is 'good' because it managed to fool the guy at the local garage when he did the yearly check. Don't try that. You will always lose when things comes to that point.

regards
Tom
GC_29

mark allison
Posts: 38
Joined: Mon Dec 21, 2009 4:30 am

Re: Historic Forest Stage Rally 124 Spider

Post by mark allison » Fri Aug 16, 2013 2:59 am

I didn't consider the 240mm rotors for a couple of reasons;
1. The lack of 13" tires in the USA is forcing most owners to upsize their wheels. Those that are still running 13" tires are faced with
using inexpensive passenger car tires. No reason for performance brakes if you aren't using perf tires. No one is making canyon runs or track days with a 4" wide cheap tire.
2. I didn't feel an upgrade that fit into a 13" wheel was worth the expense, just not enough improvement.
3. The calipers and rotors mentioned aren't used in the USA, so the expense of sourcing them in Europe prices the kit above what the market will bear.
4. The 500 parts are available now and will be for a long time, so owners can source replacement parts long after I've turned to dust.
5. Since we're using 500 parts, it's an easy installation for the diy'er. No shims or spacing is needed like on many of the Wilwood kits.
6. The braking improvement even with stock pads/rotors is pretty remarkable. Stopping distance is reduced about 25%. With the EBC performance pads and rotors it's incredible

PumaPhil
Posts: 71
Joined: Mon Apr 22, 2013 5:18 pm
Location: Lincolnshire, UK
Contact:

Re: Historic Forest Stage Rally 124 Spider

Post by PumaPhil » Fri Aug 16, 2013 9:40 am

Tom,

Many thanks for writing all that down, that's invaluable information to help me make a good informed decision about uprating my brakes. I hadn't even considered the 'track use only' aspect of Whoa! Brakes.

So this means I will probably go down the Allison 500 route but the only remaining question I have is can I still use original rear brakes? Surely with such an upgrade I may go outside the ideal '65+/35-' ratios? I was planning on obtaining X19 rear calipers as my parking/emergency brake function is inoperative on mine.

Perhaps we are now straying into making this an alternative thread?

Thanks again Tom and Mark, great information.
GC-05
'If you think experts are expensive, you should try amateurs!'

A redline run my GC's engine: https://www.youtube.com/watch?v=80nEhsJbH2w

Rallyroller
Posts: 87
Joined: Tue May 31, 2011 2:40 pm
Contact:

Re: Historic Forest Stage Rally 124 Spider

Post by Rallyroller » Fri Aug 16, 2013 11:30 am

Hi Tom + Mark



The information you have supplied is invaluable. I have already looked at Toms spread sheet regarding my car and it really is still a work in progress.
I am about to assemble the 911 front callipers , Lancia 257 vented discs etc. with 30mm spacers these will fit 13” wheels. (well they did on the bench). I will post some pics when assembled. While these are the same callipers and sizes used by the works cars (and homologated) , the actual discs and assembly is different. ( Again cost and using “standard” parts is taken into consideration)
I am looking at Porsche rear callipers on 257 solid discs on the rear. Hand brake is an issue though. Master Cylinder size ( on bias peddle box) will be decided later. (perhaps using Porsche sizes as a starter. )
As a stage rally car rear brake bias is more than on tarmac so rear brakes become more critical. It would be easier to fit the larger 38mm Fiat rear callipers on the standard discs, but I am not sure how effective they would be or how long they would last on a 10 mile forest stage.
The problem I have is keeping in the regulations. Going to 15” wheels would be great, but unless somebody has proof that Fiat rallied 124 with 15” wheels in 1974, I cannot use them. You are allowed 1” increase over standard, ie 14” but there are not many 14” rally tyres available.
The other interesting point is “legality” on the road. I am not aware of the same strict rules in the UK. ( Am I naive ?) My understanding is that if it fails due to poor modification or maintenance then you could be liable. Again using “standard” parts that were used by Fiat in 1970’s would help in any argument.

As Guy and others mention, this is a safety critical area. No modifications should be carried out without a full understanding. Just as important is good engineering practice. It does not matter how well the items are designed and made if they are fitted incorrectly!
Perhaps this should go to a separate thread, as it is an important topic, not just for a rally car.

Nigel.
GC_13

timinator
Posts: 116
Joined: Wed Mar 09, 2011 5:20 pm

Re: Historic Forest Stage Rally 124 Spider

Post by timinator » Fri Aug 16, 2013 4:50 pm

The problem I have is keeping in the regulations. Going to 15” wheels would be great, but unless somebody has proof that Fiat rallied 124 with 15” wheels in 1974, I cannot use them. You are allowed 1” increase over standard
Hi Nigel, You should go to Mark's site to verify that his brakes don't fit 14" wheels.
As a stage rally car rear brake bias is more than on tarmac so rear brakes become more critical. It would be easier to fit the larger 38mm Fiat rear callipers on the standard discs, but I am not sure how effective they would be or how long they would last on a 10 mile forest stage.
I don't disagree with this statement, however as you increase the stopping power of the front brakes more weight is transferred to the front of the car. I have found when changing from 10.5" rotors to 12" rotors that I had to decrease rear braking. I only have asphalt track experience though.

Tim

mark allison
Posts: 38
Joined: Mon Dec 21, 2009 4:30 am

Re: Historic Forest Stage Rally 124 Spider

Post by mark allison » Fri Aug 16, 2013 10:21 pm

my brake upgrade DEFINITELY fits 14" wheels on the Spider. We sell 15" aftermarket wheels since no one is making 14" wheels in a 4x98 pattern. Eventually 14" tires will become as hard to get as 13" are now, so we're concentrating on 15" wheels. But we've installed several of the kits on Spiders with 14" wheels and they have plenty of clearance. My feeling is that a 13" wheel might fit, if a spacer is used but I haven't explored that possibility

Guy Croft
Site Admin
Posts: 5004
Joined: Sun Jun 18, 2006 9:31 am
Location: Lincoln, UK
Contact:

Re: Historic Forest Stage Rally 124 Spider

Post by Guy Croft » Mon Aug 19, 2013 5:40 pm

Thanks for getting in-among this Mark.

Low profile tyres (on larger wheels) seem ok on the ordinary Spider but they are absolutely useless on the CSA with its Macpherson strut-style suspension. Half the tyre never contacts because of the camber angle.

The lower the tyre profile (eg 205/50 means the height of the tyre is 50% of the 205mm width..) the less compliant the tyre is if the suspension has much camber....

G
Guy Croft, owner

Sandro
Posts: 38
Joined: Wed Aug 30, 2006 12:30 pm
Location: Chester
Contact:

Re: Historic Forest Stage Rally 124 Spider

Post by Sandro » Tue Aug 20, 2013 3:48 pm

All,

great information and explanation of the different set ups. I agree totally on th esafety part of it, no arguments, thats why I went for parts that were OE parts and have been used before for conversions in Germany. The reason I used the Uno turbo set up is that it is a set up that works using the original CD30 Abarth alloy wheels that I have. If the 500 conversion can be used I will have a look at that too, but im not planning any track use only road use and wanted vented discs as opposed to the std solid ones tht we also smaller diameter.

As usual this forum is a fountain of knowledge and I will share my conversion once the caliper carrier mounts have been made...finding someone to machine these has been a nightmare....in the end I have modified argenta carriers.....but am looking at the machined carriers in the future when i find someone who can do it....

regards

Sandro
GC_33

fingers99
Posts: 99
Joined: Wed Dec 09, 2009 6:24 pm
Contact:

Re: Historic Forest Stage Rally 124 Spider

Post by fingers99 » Tue Aug 20, 2013 11:27 pm

We sell 15" aftermarket wheels since no one is making 14" wheels in a 4x98 pattern.
Depending on the width (and ET) you want, Compomotive (amongst others) certainly are.
GC_06

mark allison
Posts: 38
Joined: Mon Dec 21, 2009 4:30 am

Re: Historic Forest Stage Rally 124 Spider

Post by mark allison » Wed Aug 21, 2013 4:23 am

the new 500 rotors are vented and 10.25 diameter.

Post Reply

Who is online

Users browsing this forum: No registered users and 1 guest