Jump to content
The mkiv Supra Owners Club

Is there a damped underdrive crank pulley available?


PhilMorrison

Recommended Posts

I've got a bit of deja vous here as I'm sure I've already asked this, but the search says no :D

 

I'm not interested in the usual discussions on pro's and cons of underdrive, or aftermarket. I would just like to know if any of the companies out there make a damped underdrive crank pulley for the 2J? as my search results here and general google come up with nothing.

Thanks :)

Phil

Link to comment
Share on other sites

  • 4 weeks later...
Try contacting ATI in the USA, they make a vast range.

 

I have and they weren't very helpful. They definitely don't do an underdrive damped pulley.

 

Can't you make the accessory pulleys bigger, instead?

 

No, there's no room unfortunately. The powersteering pump has no clearance at all, and this is the part we really need to underdrive as we've blown approx 10 pump seals.

 

I'm sorted now anyway thanks guys. I asked on an Australian forum, and they pointed me at a product called Ross Tuffbond. I am having two damped underdrive pulleys manufactured as we speak :).

Link to comment
Share on other sites

The powersteering pump has no clearance at all, and this is the part we really need to underdrive as we've blown approx 10 pump seals.

 

That is a lot of pump seals, are you sure that the pump/ PS system is OK, I run 8750 rpm using all stock size pulleys. Apart from a collapsed PS hose I have had no problems.

Link to comment
Share on other sites

It's because when you are on full steering lock at 100mph and 8000 RPM it seems some heavy curb clipping can add just enough back pressure on the rack to make the front seal on the pump very unhappy. It is very much a revs related problem though, as on my car that only revs to 7600 it doesn't happen so often, and when we used to run one of the cheapo undamped underdrive pulleys on the car that usually pops them all of the time, it didn't have a problem even at 8000rpm. We just don't want to use the cheapo pulley any more as it may have contributed to the early demise of one of our engines.

 

Is that a 2JZ you're running at that RPM? that's impressive.

Link to comment
Share on other sites

It's because when you are on full steering lock at 100mph and 8000 RPM it seems some heavy curb clipping can add just enough back pressure on the rack to make the front seal on the pump very unhappy.

 

I guessed you might be on full lock at high rpm, after I posted. So realised rpm is far more of an issue for you. Lets hope the AUS guys can sort out your problem.

 

 

Is that a 2JZ you're running at that RPM? that's impressive.

 

Yes with my VWR built motor, it will take 9000rpm, but I decide to set the limit a little lower. It is very addictive

up that end of the rev range, I have to use those rpm every time I take it out.:D

Link to comment
Share on other sites

Phil as your tight for space have you considered a remote pump? im thinking of giving the Mr2 turbo pump a go

 

It has crossed my mind, but I'm not sure it could withstand the pressures that drifting puts on the steering system. It's quite a lot of work to test and have it fail.

 

...or just ditching the power steering.

 

Definitely not an option. The force need to pull a car off full lock when you have the amount of steering we do is ridiculous, and can actually be pretty dangerous when the steering gets stuck :D.

Link to comment
Share on other sites

The fittings are Aeroquip, they are big enough and flow and cooling is good. We've had a few different racks as well.

It's not just on one car, but on the main culprit we blew seals for a year, then fitted an underdrive pulley and didn't blow any for 6 months, then blew the engine and went back to a normal damped pulley and we started blowing seals again.

We're not just replacing seals by the way, we are replacing pumps.

I'm open to the idea of it being some other part of the system causing the failure, but with having no failures when using an underdrive pulley before, and a fast approaching new season. that's enough for me to purchase two damped underdrive pulleys at great cost :D

Link to comment
Share on other sites

Phil we had a similar problem on a 2J, though it turned out to be the additional pump support arm that had been fitted. The pump drifted very slightly out of skew but not enough to cause belt damage. Seemed extra strain on the Vane shaft and bearing assembly at high rpm caused no.2 seal to start weep

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. You might also be interested in our Guidelines, Privacy Policy and Terms of Use.