Old style 5kq 'round' TB seized

[Louis-Alain Richard]

Vittorio,

It's funny since I dismantled my round TB (stock WX engine from an
urQuattro) no later than last week. Indeed, there are needle bearings but
mine were in good shape even if the car is an 1983. They are press fit in
the TB, so rebuilding would need special tools but it is not impossible.

Let me ask you one stupid question. Are you sure the bearings were faulty ?
There is, at least on my WX, 3 strong return springs so for a bearing
seizing so hard that it wouldn't move under all that backforce, it surprises
me a bit. You should have felt it in the gas pedal before, unless you are
really "lead footed"... :-)

In fact, a few years ago, one of the bolt of the air temp sensor on the top
of the intake came loose and stuck the throttle partly open (while stopping
at a red light !) I too looked at the TB itself, just to discover the small
bolt preventing the complete closure of the butterfly. It is amazing that
such a small angle of the butterfly can produce so much (unwanted) power. 

To answer your original question : the easiest route would be to find a
known good used unit. And then, find the reason they fail (gas pedal that as
no stop so all the driver's force is transmitted to the TB ? Bent shaft ?
Mud accumulation ? An old girlfriend that pour acid on your engine at night
? Genuine bad luck ?...)

Oh finally, check if the springs are correctly installed. On my first
attempt, I thought I was right, but the return force was too weak, so I
checked another one I had and indeed, installing all the bits in the correct
position demands good eyes, fine fingers, and patience. Now the cleaned one
is very firmly sprung back on its stop and its motion is well lubricated. I
can send you pictures if yours is similar to a WX unit.

Louis-Alain



> -----Message d'origine-----
> 
> Hi - we had a throttle stick wide open on the rally car this weekend -
> luckily it was the last thing that happened *after* we got her on the
> trailer.
> 
> Discovered that each end of the butterfly shaft has a needle bearing on
> it. One of them seized right up and would not allow the shaft to turn
> freely. I believe this may have been the issue in a previous TB I had as
> well...
> 
> Now, my quandary is what to do next - I can go buy another TB, but that
> one is also going to be 20yrs old - and potentially have the same issue.
> Can these be rebuilt? If so, does anyone have any leads? If not, any
> recommendations on what to do next?
> 
> Thanks,
> 
> Vittorio -