34 replies to this topic

[Fat Cat]

Greetings SM community!

Having been a supplier to SM but not involved on forums, FCM will be more engaged in the Spec Miata racing world. We recently acquired an AccuForce gas shock fill machine that allows us to legally service the Spec Miata Bilsteins (no Schrader valve used). Having read through threads here and elsewhere, my interest is providing compliant shocks - whether a refresh/rebuild or optimizing to the rule allowances. Because of concerns with test methods (screwdriver in the lower bushing?!), I will get whatever information I can from SCCA and also plan to work with racers to ensure consistent test results between our Roehrig 2VS and their test methods.

I also have spoken with John Mueller in the past but not on these exact topics. Having a consistent shock test spec between SCCA and NASA just makes sense, especially for racers wanting to run with either group.

I'm in the process of revising our website to give comprehensive pricing, information and ordering capability. FAQs are being created so I can spend more time in the back assisting my shock technician (who is currently solely responsible for about 90% of shock work we do). I end up being at the keyboard too much, not my favorite place to be, but I like to engage with customers, share information, learn, etc.

If demand becomes strong from SM, even better. The techniques for building shocks are subtle but I've already passed my knowledge on to a technician and continue to hire more shock techs as the need arises. We're proud to achieve high consistency and exceptional results, Bilsteins make that rather easy with their high quality components. At heart, everyone at Fat Cat is a Miata enthusiasts (everyone in our shop owns and competes one) and we may even build a Spec car this for 2013 to help the development process.

Glad to be on this forum (thanks Jim!). Please post your questions here. Our Spec Miata specific email address is fcm.specmiata at gmail.

Regards,
Shaikh

[trimless]

Shaikh,

That's great news! Always enjoyed your great service in the past and look forward to your future involvement in the SM community.

[Alberto]

Awesome news indeed. Especially since I live 20 minutes away from you.

Let me know when you are ready Shaikh. I'm ready to have my 1.5 season old shocks freshened. We already know the pax rear is off 10% from when you dyno'ed it a month ago.

[James York]

I have a set in my spare sparts just waiting for a good rebuild.

[Cnj]

I have a set in my spare sparts just waiting for a good rebuild.

Good idea. Maybe that will help you

Cnj

[Fat Cat]

Thank you, gents! Alberto, I feel that next week we'll be ready. I'm doing a promo event in Houston (Miata Round-Up!) as official sponsor which I'll thoroughly enjoy, but very eager to get back into racing and start our Schrader-less revalve/rebuild program for all kinds of shocks, SMs very much included.

Shaikh

[pat slattery]

Nothing like a little competition. Good news!!

[Fat Cat]

Update: Having reviewed the established shock specs and made appropriate fixturing for our shock fill machine, we've started to do SM rebuilds. I'm making major, long-overdue improvements to our website and will have a dedicated SM page up soon but for now, this service/pricing guide will have to do:

 

 

• FCM-SM-F, $105, "reFresh": new seals, same shims, new oil, "after" dyno provided (vs. no dyno from Bilstein when ordering new shocks), other repair parts extra

• FCM-SM-R, $135, "Racer": SM-F plus new shims / time required to be within 25-30% of spec'd forces

• FCM-SM-X, $165, "Xtra": SM-R optimized to 10-15% of spec'd forces

 

All our shocks are built with the intention to comply with current SCCA/NASA shock specs. Variations may exist between different shock
dynos so we'd rather err a bit on the softer side. Each FCM-tuned SM shock will come with a dyno sheet tested at the velocities indicated in
the spec sheet. Final validation of compliance is up to you. No refunds or 'free rework' will be given. If you order the FCM-SM-X and are fast
enough to be concerned, I recommend sending your shocks in to SCCA for verification of compliance.

 

We will not perform dyno tests unless part of one of the services above. Simply too busy for that.

 

There are already a number of customers who've sent their shocks in and I've added another shock tech to help with overall production. We'll be offering complete new SM setups (full coilover) as well. Expect about 2-3 weeks after receipt of shocks before work will be performed. Please don't send us your only set of shocks and expect them back in 2 weeks. We want to take care of you guys but I know how racers can get... ! Yes, we will finish it quickly and call you back within a day (or two) if you have questions. In general, email may be the best way to contact us. I will be on business in Europe for most of May and will have my team handling operations while I'm out.

 

If you have questions not answered here please email me through the site or at suspensiontruth at gmail.

 

Look forward to continuing our support of Spec Miata!

Shaikh

[Rob Burgoon]

Update: Having reviewed the established shock specs and made appropriate fixturing for our shock fill machine, we've started to do SM rebuilds. I'm making major, long-overdue improvements to our website and will have a dedicated SM page up soon but for now, this service/pricing guide will have to do:

 

 

• FCM-SM-F, $105, "reFresh": new seals, same shims, new oil, "after" dyno provided (vs. no dyno from Bilstein when ordering new shocks), other repair parts extra

• FCM-SM-R, $135, "Racer": SM-F plus new shims / time required to be within 25-30% of spec'd forces

• FCM-SM-X, $165, "Xtra": SM-R optimized to 10-15% of spec'd forces

 

All our shocks are built with the intention to comply with current SCCA/NASA shock specs. Variations may exist between different shock
dynos so we'd rather err a bit on the softer side. Each FCM-tuned SM shock will come with a dyno sheet tested at the velocities indicated in
the spec sheet. Final validation of compliance is up to you. No refunds or 'free rework' will be given. If you order the FCM-SM-X and are fast
enough to be concerned, I recommend sending your shocks in to SCCA for verification of compliance.

 

We will not perform dyno tests unless part of one of the services above. Simply too busy for that.

 

There are already a number of customers who've sent their shocks in and I've added another shock tech to help with overall production. We'll be offering complete new SM setups (full coilover) as well. Expect about 2-3 weeks after receipt of shocks before work will be performed. Please don't send us your only set of shocks and expect them back in 2 weeks. We want to take care of you guys but I know how racers can get... ! Yes, we will finish it quickly and call you back within a day (or two) if you have questions. In general, email may be the best way to contact us. I will be on business in Europe for most of May and will have my team handling operations while I'm out.

 

If you have questions not answered here please email me through the site or at suspensiontruth at gmail.

 

Look forward to continuing our support of Spec Miata!

Shaikh

 

Heh, sorry Shaikh.  Didn't realize you weren't cool with just dyno service.

[Fat Cat]

Hey Rob, no worries! You asked, I said yes and was happy to do it; helped us understand some nuances about inherent variations in Spec shocks so that was valuable for us. I just had to be realistic about doing that for hundreds of other people.

[Blake Thompson]

I have a set in my spare sparts just waiting for a good rebuild.

 

As I don't, turnaround time would be critical for us.

[William Bonsell]

Just curious as to the realistic life cycle of the shocks for a mid pack racer. And is there a way to notice on the track if re-valving is needed? Embarrassed to admit I'm on my 4th year....think they're due?

[Juan Pineda]

Hey Shaikh, I've tried calling and Emailing this week about getting some Shocks rebuilt. No answer so far. How can I schedule? I'm local and can drop them off. Obviously I'm concerned about getting them on your schedule to coincide with my race schedule. Thanks! -Juan

[Juan Pineda]

Finally got a hold of Shaikh. Lots of good info there! One thing we discussed that he did not know is the accuracy/tolerance of shock dynos. So for those in the know, do you have some understanding of this? Is it like engine dynos that vary significantly between manufacturer? Obviously I'm interested to get some perspective on the risks of pushing the boundaries of the specifications.

[makus0025]

Just curious as to the realistic life cycle of the shocks for a mid pack racer. And is there a way to notice on the track if re-valving is needed? Embarrassed to admit I'm on my 4th year....think they're due?

 

Anyone have any input on this?  I know I have at least 4 years on my too, should we ever be concerned of them failing?

[john mueller]

Just curious as to the realistic life cycle of the shocks for a mid pack racer. And is there a way to notice on the track if re-valving is needed? Embarrassed to admit I'm on my 4th year....think they're due?

 

It really depends.  Do you spend a fair amount of time not on the racing surface?  Bang hard off curbing?

 

You can remove them and have them dyno'ed, but the easiest way to tell is by visual inspection.   Is oil leaking/seeping from around shaft?  Is busing distorted/cracked/ crushed?

[Fat Cat]

Update: We have (2) front and (2) rear shocks built to FCM-SM-X specifications about to be tested by SCCA the next couple days. We'll post the outcome of those tests.

After my detailed conversation with Juan I called Roehrig and spoke with one of their tech experts re: dynos accuracy/calibration. He indicated they have calibration procedures but found them largely unnecessary. The load cells are very consistent and repeatable as long they're not overloaded (which we're careful NOT to do). He pointed out diagnostic functions in the hardware while I was on the phone and our data registers were in their nominal (centered) positions. Our own results have been very consistent over the past 6 years (set up a valve stack, matching between pairs of shocks, or similar recipes, are consistent within a few percent). The combination of Bilstein machining, our attention to detail while assembling and Roehrig's measurement consistency have served us well so far.

Ultimately, our goal is to build legal, validated shocks for Spec Miata racers that you'll find faster and more fun to race on. The 'green' side of me would also rather NOT see tons of old Bilsteins go into landfill so this is a win/win for everyone to focus on refreshing/rebuilding/recycling. We can provide brand new revalved shocks as well and even complete ready-to-install assemblies

[Fat Cat]

From Christopher Blum, SCCA Technical Services, April 25, 2013

Subject: Spec Miata Shock Measurements

 

The Spec Miata shocks were measured on SCCA’s A-Line shock dyno on April
25, 2013. Below are the specifications for Spec Miata followed by the results of
your shocks. All shocks measured, were found to be in compliance with the
official SCCA Spec Miata shock specs. If you have any questions or
concerns, please contact the technical service department.

[marcusmazza]

A few comments reagrding shocks and testing procedures.

 

1. Roehrig shock dynos are very repeatable as long as they are in calibration, and they are of the same type, i.e. crank dyno vs. an EMA (and I'm not just saying this because I used to work for Roehrig). I'd imagine there will be some variability when comparing data across different manufacturers.

 

2. What is the test specification being used? Is it a CVP test or a PVP test. If its a PVP being used, the variability between different dyno manufacturers should be less. It will also make the use of screwdrivers as clevis plins less of an issue. CVP tests are more sensitive to play in the yoke mechanism, slight velocity changes throughout the stroke, loos clevis pins, etc.

 

3. The Bilstein tuning for the spec shock is garbage. Not just because of the variability, the overall tuning sucks. There is no compression damping what-so-ever, and the rebound damping is almost progressive untill you hit the knee and it starts going digressive. I've seen similar tuning before, mostly on the rear shocks of mountain bikes. Re-building them to match or even re-builing them to the edge of spec is like polishing a turd.

 

4. In order to make a noticable change in the handling of the car, or lap times, the valving change needs to be huge. I have some data on the spec shocks that I plan on posting soon (sorry, CVP only) and some data on a 'cheater' shock (CVP and PVP). The 'cheater' shock data is very similar to what the Brits are using. My understanding is their version of spec miata has open shock tuning rules.

 

5. There are a few ways to tell if you're shocks are going bad. As John pointed out, check for leaks, cracks, etc. Also, you can check the gas pressure by pushing on the shock rod. I believe it should be roughly 20lbs of force to compress a miata shock. After that, there isn't much that goes bad on a shock. The valving doesn't really wear. Really, the only other wear item that could lower the shock forces is the piston seal. No easy test for that one, short of putting it on a dyno.

 

 

-Marc

[john mueller]

For those who care, here are NASAs SM Shock Testing Procedure