keeping shocks temps down....there WAY to hot

[95_Bronco]

okay so at the last MDR Plaster City race we came in for a pit/driver/codriver change after the first lap and while a buddy was running around the truck shaking the tires to check for wheel bearing issues (which weve been having) he touched the shock body and roasted his fingers in a matter of seconds, we put a heat gun on it and it said 450 !!! how do we keep them down.

FYI there on the back of a curt leduc built 7s ranger. the shocks are 3.0 SAW 16" tripple bypasses

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[Nick]

It sounds like it may be a valving issue.

[convoy]

If you've looked at the valving and check the PSI then look at an external way to dissipate the heat. Cheapest would be to allow air to circulate around the shock and reservoir more efficiently. Relocate the reservoirs away from heat sources. You could possibly run some sort of oil heat exchanger midstream between the reservoir and shock body, or thirdly would be to install fins on the reservoir.

[magic carpet XLT]

could be air in the shocks. or the bypass tubes could be all the way closed.

[randomthoughtsracing]

-Dont have the exhaust dump upstream of the shocks.

-What pressure are you running?

-If you are oversprung then there may be quite a bit of rebound valving trying to control the rear. To little spring and there may be too much compression valving...

-If the heat gun is the infrared type it needs to be pointed at a non reflective surface. Shiny shock bodies throw off the readings.

-Try a Howe power steering cooler with as short of a hose as possible.

[philofab]

I was going to post that same picture Joel! A 3.0 should not be overheating on that light of truck.

[billy1911]

The 1 car I chased for in the 1000 burned the fox decals on the reservoir. One shock blew the seal the other worked fine.

[SteveG]

-Try a Howe power steering cooler with as short of a hose as possible.

Cool shock, Joel. I wonder if that cooler would work significantly better in a piggyback configuration then with the reservoir hose ported off the bottom of the cooler.

In a bypass with the reservoir hose ported off the bottom of the shock body you could put the cooler right on the shock and remote mount the reservoir with a hose. Maybe even add a large block between the shock body and reservoir to aid heat-sinking. It would be fun to experiment with stuff like this.

[Nick]

Cool shock, Joel. I wonder if that cooler would work significantly better in a piggyback configuration then with the reservoir hose ported off the bottom of the cooler.

Hmm...that's a very interesting idea. My 2.5's are piggybacks ported off the bottom of the shock. What do you think of replacing the existing resi with a power steering cooler, then adding a 3.0 resi after that?

If shock temperatures become a problem it might be something worth trying.

[Deleted Account]

Racing not at Plaster City makes the bigest differance.

[philofab]

Hmm...that's a very interesting idea. My 2.5's are piggybacks ported off the bottom of the shock. What do you think of replacing the existing resi with a power steering cooler, then adding a 3.0 resi after that?

If shock temperatures become a problem it might be something worth trying.

A 3.0 resi is only bigger because of the added shaft volume it needs to compensate for. There is not much more surface area to help cooling. You would be better off doing a one way valve and a return line so the oil circulated in the shock.

[bajascott]

Racing not at Plaster City makes the bigest differance.

hahahahahahaha yea you are right. i raced there in a 9 car and 5/16 car in the early 90's and it was BEAT then.

[Nick]

Hmm...that's a very interesting idea. My 2.5's are piggybacks ported off the bottom of the shock. What do you think of replacing the existing resi with a power steering cooler, then adding a 3.0 resi after that?

If shock temperatures become a problem it might be something worth trying.

A 3.0 resi is only bigger because of the added shaft volume it needs to compensate for. There is not much more surface area to help cooling. You would be better off doing a one way valve and a return line so the oil circulated in the shock.

I wasn't really thinking in terms of surface cooling area, i was thinking about the added oil volume. The resis on a saw piggy back are teenie. I was thinking that adding the cooler, and a larger resi would be beneficial.

[philofab]

Hmm...that's a very interesting idea. My 2.5's are piggybacks ported off the bottom of the shock. What do you think of replacing the existing resi with a power steering cooler, then adding a 3.0 resi after that?

If shock temperatures become a problem it might be something worth trying.

A 3.0 resi is only bigger because of the added shaft volume it needs to compensate for. There is not much more surface area to help cooling. You would be better off doing a one way valve and a return line so the oil circulated in the shock.

I wasn't really thinking in terms of surface cooling area, i was thinking about the added oil volume. The resis on a saw piggy back are teenie. I was thinking that adding the cooler, and a larger resi would be beneficial.

Oil volume will only help if it circulates... the oil in a shock does not.

[tcm glx]

Oil volume will only help if it circulates... the oil in a shock does not.

But more oil volume means it stays cooler doesnt? I mean if I understand correctly, 10 qts stay cooler than 5 qts right? (as an example)

[philofab]

Oil volume will only help if it circulates... the oil in a shock does not.

But more oil volume means it stays cooler doesnt? I mean if I understand correctly, 10 qts stay cooler than 5 qts right? (as an example)

If it circulates... but nothing really does that in a shock other than maybe a little convection.

If more volume automatically meant cooler shocks everyone would sell a 2.0 shock with a 4 gallon resi.

[Nick]

Oil volume will only help if it circulates... the oil in a shock does not.

But more oil volume means it stays cooler doesnt? I mean if I understand correctly, 10 qts stay cooler than 5 qts right? (as an example)

If it circulates... but nothing really does that in a shock other than maybe a little convection.

If more volume automatically meant cooler shocks everyone would sell a 2.0 shock with a 4 gallon resi.

I got this line of thinking from some old class 11 guys. Since as we all know they are restricted as to suspension, they would use huge resis on their shocks to help keep things cool. Further, look at the pic that Joel put up, a huge blackhawk resi on a 2.5.

[SteveG]

The Blackhawk reservoirs have valving in the reservoir which will also create heat... not the case with a non-Blackhawk reservoir.

[randomthoughtsracing]

Exactly, the shock pictured above does generate heat at the reservoir due to the second valve stack. The length of hose pictured on the coilover would definately not be ideal for any heat exchange.

Try some rough math on the hose volume vs. the rod volume.

-8 hose is 7/16ID = .4375" this gives a 12" -8 hose an internal fluid volume of around 8.24 cubic inches.

7/8 rod is .875 giving it a displecement of 1.373 per inch of rod stroke.

So in order for even a little bit of fluid (let alone a big shot) from the shock to reach the reservoir the shock would need to cycle over 6". An 18" hose would need more than 9" of stroke.

As a subsequent design I ran this setup on the front of AGM's class 1 car at the 1000. The piggyback reservoir is full of fluid and the second reservoir houses the dividing piston. San Felipe is coming...

The Blackhawk reservoirs have valving in the reservoir which will also create heat... not the case with a non-Blackhawk reservoir.

[SteveG]

Another cool shock, Joel!

This might be bordering on top-secret here, but what kind of valve changes (in the shock) were you able to make because of the Blackhawk reservoir? Did you have to lighten the valving to get the same damping?


I know the Blackhawks are only for Bilsteins, but they sure would look good attached to a pair of these.