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Author Topic:   Power Steering ??
Dirt Forum Champ
Total posts: 796
posted October 03, 2005 10:42 AM  
Were running a Sweet pump, head mounted, belt wraps the crank pulley, and the water pump pulley then over to the power steering pump. Pump has a 6" pulley.

Question, it seems to be cutting out at high speed or high load. Could the pump be over driven? or could it be on its way out?

How do have yours set up? i was thinking about running it off the crank mandrel off a 3" v-belt pulley to slow it down.



Dirt Freak

Total posts: 209
posted October 03, 2005 11:42 PM  
we run, on our late model, dual belts from crank to water pump - 35% reduction. we then have a 4" pulley bolted to the front of the water pump pulley which drives the standard sweet/gm style power steering pump via a single belt on another 4" pulley - 1:1 with water pump/ 35% reduction to crank rpm. the power steer drive pulley (bolted to water pump) used to be approx. 2 1/2" diameter, but that coupled with the 35% reduction from the crank was too much reduction and could not provide enough power assistance. this setup, which we have run for the best part of 3 seasons has proved effective and trouble free.
our fuel pump is belt driven via a crank mandrel mounted pulley & toothed belt.

sc1 racing
Dirt Freak

Total posts: 419
posted October 04, 2005 12:40 AM  
the pump should stay under 6,000 rpm. so yes it could be over pumping. i cant remeber off of my head but some how you multiply your desired rpm in to your pulley to figure out what rpm it is turning. but you want power steering pulley to be smaller than crank pulley.most likely if it is stoping pumping the damage has been done.also make sure belts arent slipping.

Dirt Forum Champ
Total posts: 505
posted October 04, 2005 07:07 AM  
If your ps pulley is smaller than the crank pulley then the pump would be overdriven not underdriven.

(crank pulley/ps pulley) * engine rpm = pump rpm

We run a similar setup 1:1 crank to water pump and a ~15% reduction on the ps. With one belt running wp to crank and a second running wp-ps-crank. We turn ~8500 and have never had a cavitation problem.

If I remember correctly you don't turn your motor too hard so if the pump is no more than 1:1 with the crank you shouldn't be having problems. To me it sounds like a symptom on a failing pump or slipping belt.

I just noticed the 6" pulley. Most 1:1 crank pulleys are ~5" so that would mean you ps pump is already underdriven. I think if you went to a 3" crank pulley would cause the pump to turn to slow at low rpm and cause more problems.

[This message has been edited by wfoondirt (edited October 04, 2005).]

Dirt Forum Champ
Total posts: 796
posted October 04, 2005 07:18 AM  
I checked that its a 4.5" pulley. I called Sweet and they seemed to think its the pump going out, slowly. It does have 2 seasons on it. The guy told me they rebuild them for $75.00, so i might do that this winter, or buy a new KSC pump.

Your correct we only crank 7500 rpm max. The Pulley's is a reduction set, the WP and crank pulley. I'll measure them to find out how much smaller it is. I believe the crank pulley is 5" and the WP is 6", i think.

Dirt Freak

Total posts: 270
posted October 04, 2005 07:27 AM  
What kind of hose are you using for the supply line from the tank to the pump? If you use a hose that is not rated for vacuum(suction) it can collapse at high rpm which is the greatest draw and restrict flow to the pump.Alot of folks figure they can get pushloc hose to work because the supply hose isn't under pressure. We did. We soon figured out that(with the same problem you are having) when the fluid gets warm and softens the hose up it collapses under draw.
Use a hose that will withstand vacuum. We use hydraulic line (-10) now and no problem.
I have been told of the possibility of the internal by-pass sticking is also not un-usual, but not normally on a Sweet pump. Good luck!

Dirt Freak

Total posts: 402
posted October 04, 2005 10:06 AM  
Make sure you have at least %35 contact area of the belt and pulley. the more trhe better. The head mounted pulley's close to the water pump as possible is the best bet to ensure best contact. Moving the pump further away from the water pump will decrease the contact area at the crank pulley. Couple this with the load of the water pump and it may slip.

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