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Sudden terrible rear wheel hop

4K views 9 replies 3 participants last post by  jamitt 
#1 ·
I'm now experiencing terrible rear wheel hop when driving over rough or bumpy roads. No unusual noises from the rear, but the rear also feels much stiffer than usual. Seems to be worse from the left rear. Really bad when turning on bumpy roads but even have hop when driving straight on bumpy roads. Is this bad rear shocks, differential mount, or something else?

(Tire pressure is 38psi)

Any ideas?

2006 SP6 91k miles, stock suspension

Thanks.
 
#4 ·
Yes, I will check it all out this weekend.

BTW, 38 PSI is the recommended tire pressure and what I have been using since 2006.
 
#3 ·
I'm going to vote for a blown shock, and at your mileage I'd consider replacing all four corners. If you're not going all fancy suspension, then Tokico Blues (~$400) are a good budget replacement, with Bilstein HD's (~$500) being next up and not too much more money.

I'd encourage getting the back end up in the air & tires off so you can take a really good look around to be sure everything is in good shape and make your plans from there.
 
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#5 ·
Yes, will do. Need to check the brakes pads anyway and paint (again!) the rusting rotor hubs, so won't be a wasted effort.

I have always been a Bilstein fan, but sometimes they are too stiff. How do the HDs compare to the stock shocks?

Thanks.
 
#6 ·
Good to know, didn't know the ms6 required that much psi.

Billstein HD's are a great handling shock, but IMO way too stiff for a DD. That's on my v6 tho, I've heard good things from a buddy who ran them on his ms6, but it was a purely track vehicle. Maybe they're better with the increased weight of the speed. They're rocks in the rear of my 05 sedan tho.
 
#7 ·
The stock Mazdaspeed custom valved KYB's are really a great shock. We've never found a perfect match out in the wild. The Tokico is a touch softer than stock, the Bilstein a touch stiffer.

The thing is, after 90+ thousand miles anything is going to be so much of an improvement that you'll be amazed how bad the originals have become. The degradation just happens so slowly over such a long time that you haven't noticed.

So, what to get, providing shocks are indeed found to be the problem, and really, at 90K they're a problem regardless(!), depends on your goals and driving style. With the extra weight and performance of the Speed6 over the normal 6 the Bilstein fits well and has outstanding reviews. OTH, if you just want to replace the part, and daily drive cruise to the office is all your doing, then Tokico > OEM KYB > KYB GR2 > Bilstein HD is the progression from soft to firm.

For reference, following is the stock part numbers & prices (retail then Mazdaspeed Motorsports). The OEM KYB's are available & in country tho your local dealer may need to order them.


Code:
GP9A-34-700D    DAMPER(R),FRONT     $119.59 / 71.74
GP9A-34-900D    DAMPER(L),FRONT     $119.59 / 71.74
GP9A-28-700C    DAMPER,REAR         $ 78.25 / 46.94  (x2)


Retail cost for full set - $395.68
Mazdaspeed Motorsports cost - $237.36
 
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#9 ·
Thanks, great post--exactly what I was looking for.

After inspecting the rear end of the car this morning, there is no question that the left shock is blown--fluid everywhere. Everything else looked in order (but I'm no suspension expert).

My Speed6 is my everyday driver driven on some horribly rough DC city streets (many of the roads around the region have not been repaired after the severe winter last year), so I will likely go with the OEM shocks. I found them to be a good balance and they are very affordable. While I love Bilsteins (I put them on my Audi Quattro) I'll go with what makes sense now for this car.

A couple of online Mazda dealers are selling them for slightly more (~$10) than Mazdaspeed Motorsports, and my local dealer usually matches online dealer prices, so I will give that a try.

Thanks again. You guys are great!
 
#8 ·
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