Industry Insider: Tein's shock service

by Mike Kojima

One of the markings of a better shock company is if the company can service their product by offering rebuilding and revalving if the the customer needs it for their usage.  We recently visited Tein Suspension since they are rebuilding and revalving the shocks on our Project Supra

Our Supra is equipped with Tein Flex coilovers.  The Flex is Tein's high performance twin tube street coilover which is singly adjustable for rebound damping and independently adjustable for ride height and droop with a height adjustable spindle or control arm mount.

We sent the Tein Flex coilovers back to Tein sothat they could be rebuilt and upgraded to the latest valving spec for this application.  Since these shocks were installed on Project Supra many years ago, Tein has come out with something they call an advanced needle valve which improves ride quality.  The advanced needle valve comes with an entirely different piston valve spec as well.

Let's take a look at what is involved with rebuilding a shock and take a look inside at exactly what Tein does when you send your shocks back to them for service.


We brought our Tein Flex coilovers to Tein's Southern California headquarters to get our servicing done.
Our coilovers are checked in and the part numbers verified before the work is started.  The Bill Of Materials (BOM) is pulled so the specs of the shocks can be confirmed as the shock is disassembled. 
Tein's R&D staff disassembles the shock once the shock's part number is verified and the BOM is pulled.  He starts by taking off the camber plate, spring, bump stops, bump rubbers and dust shields.  He will also remove the spindle or control arm mount. 
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Wednesday, January 28, 2015 12:08 AM
Awesome article, thanks very much for the walk through.

I have to ask though, using calipers, even a Mitutoyo 0-6" to check inside diameters? No gage pins? Surely this was for photos right?
Mike Kojima
Mike Kojimalink
Wednesday, January 28, 2015 1:05 AM
Calm down it's a shock not an electron microscope! Thats not a part of the shock that has tight clearances, just high wear.
Wednesday, January 28, 2015 5:21 AM
Pretty cool! What other aftermarket damper companies off this service? I assume KW and Koni do, but are there any others? Also, what is the cost of this service? Or if you all don't want to divulge that, how does the cost relate to buying a brand new set of dampers?
Wednesday, January 28, 2015 6:55 AM
This is really neat! If you guys could do an insider look at Feal's revalving service that allegedly turns "lifestyle" shocks into decent performers, that'd be cool too.

Especially since the forums for my car are flooded with ~$400 used T1R and buddyclub coilovers, a $600 feal rebuild/revalve for a total of $1000 for high performance coils seems pretty reasonable.
Wednesday, January 28, 2015 8:06 AM
Bilstein will also service and revalve shocks, that's something I'd like to try for my Miata. Plenty of circle track shops will do the same as well, and you end up with a user serviceable and revalvable shock.

Then the problem is you've got to figure out your own shim stacks.

Mike Kojima
Mike Kojimalink
Wednesday, January 28, 2015 10:24 AM
Just about any high quality. not low end asian shock companies will service their product.
Wednesday, January 28, 2015 11:15 AM
Using guage pins to measure a DRILLED hole??? Drills in a mill are +/-0.005". In a bench drill like that, probably +/-0.010". But like Mike Kojima said, that hole really doesn't matter provided it is big enough to flow considerably more than the valve.

Interesting to see the Tein internal components. Seems like they use a lot of parts where machining tolerances would have a signifigant impact on valving. Looks like even the shims are machined with steps in them.
Wednesday, January 28, 2015 4:57 PM
Yeah, at the end of the day this isn't a high precision race damper. But it also doesn't cost as much and lasts much much longer. I'd be ok giving up that bit of variability if I get a nice long service interval. In fact, my ITS car uses revalved Tein Super Streets and it sees no street use whatsoever.

The one thing I'm curious about is what the damper internals for the Type N1 and Gr.N look like. Not for any practical reason other than for comparison purposes.
Wednesday, January 28, 2015 6:38 PM
Great article; thanks to you and Tein for allowing this really nice step-by-step walkthrough of all things to do with damper construction. It had been a bit of black magic to me up to this point -- perhaps still is a little. :)
Wednesday, January 28, 2015 7:30 PM
Mike what's your opinion in general of more compression oriented valving vs. this which has alot more rebound damping? Let's say the application is a fun weekend street/track car.
Mike Kojima
Mike Kojimalink
Wednesday, January 28, 2015 11:34 PM
My rule of thumb in a very broad general sense is maximum compression and minimal rebound.
Thursday, January 29, 2015 12:20 AM
Great article. I like rebuilding dampers now, but I was pretty nervous my first time. If you want *alot* of experience, start riding/working on MTB suspension. Because of the operating conditions, you end up having to service them *very* frequently. I can't tell you how many times I've rebuilt my dampers in strange places like gas station restrooms. The most important part is the washing/cleaning of all surfaces and blow drying from my experience. If you use paper towels they leave fibers all over that screw with the sealing.

Nothing better than a newly serviced damper.
Thursday, January 29, 2015 9:15 AM
That is my thinking as well, but so many dyno graphs I've seen of aftermarket coilovers and shocks have alot more rebound compared to compression. Seems this would cause jacking down, making the bumpstop come into play more often and reduce the suspension's overall effectiveness.
Dan DeRosia
Dan DeRosialink
Thursday, January 29, 2015 9:34 AM
It's weird seeing the insides of twin tube shocks, even if there's some advantages here and there. The shock dyno looks useful at least at some clicker levels. I can't help but think that with the big difference between compression and rebound at full stiff, the suspension would jack down a lot. It's interesting how well the clicker seems to do at not affecting compression much.
Mike Kojima
Mike Kojimalink
Thursday, January 29, 2015 9:44 AM
We explained why in the story. The needle valve is a lot bigger which allows for more fluid to bypass the valve.
Dan DeRosia
Dan DeRosialink
Thursday, January 29, 2015 11:29 AM
Oh, yeah... I just mean as distinct from most monotubes (barring those with check valves) where the needle valve changing bleed across the piston affects rebound and compression. Is the foot valve mostly acting on the fluid displaced by the shaft? As I said, I'm really not used to thinking about twin tubes.
Pablo Mazlumian
Pablo Mazlumianlink
Friday, February 13, 2015 7:23 AM
Thanks for the write-up and pics, Mike and Jeff! It's impressive to see just how much goes into reman'ing a damper.
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