Hot steering

[supersportsp]

'97 Caterham LHD with a carb'd Zetec.

 

Issue: Hot day, had to do an emissions test and car got even hotter with extended running without movement. Pulled out from the testing station (I failed in case anyone thinks there is some kind of miracle EPA compliant Weber fed Zetec trick), and pulling onto the road the steering got very heavy, particularly on center. It was like the tires dropped to 2-3 lbs. I thought maybe at first it was the ZZR's sticking to the hot pavement, but the stickiness wasn't consistent over the whole range of the rack, with the issue more on center.

 

Don't know what it is like for Crossflow folks, but with my Zetec and header, the steering shaft passes right between the header tubes, with maybe a 1/2" clearance. It probably gets quite toasty, particularly on 90+ degree days like it was yesterday. The header tubes are wrapped, but that is high heat intensity right next to the shaft.

 

So, I am wondering if something is maybe happening with the shaft itself, or if it is conducting heat down into the rack and causing issues there. Once the car cooled down it drove totally normal. Anyone else ever have this issue.

 

[Shoe String Racing]

Power steering? I've had mine go out completely on track on a hot day in as few as 4 laps. But then it came back as I backed off and drove 70%. Did that consistently thru 3 sessions.

 

Everyone I asked told me it was overheated fluid. I put a small transmission type cooler on it (the 3-4" diameter aluminum tube type with fins going thru it for full contact with the fluid). Besides the fins cooling, I doubled the volume of the PS fluid which of course also helps the cooling as well.

 

If you have a manual rack I have no clue

[coffee break]

If there is enough clearance, you could wrap the steering shaft with the same material to reduce the heat input to the shaft. The shaft may have transferred heat to the internals of the rack causing bearing clearance issues.

[supersportsp]

Power steering?

 

Ha! I don't even have a hydraulic clutch in my car.

[Davemk1]

Any signs that the steering shaft has been rubbing on the exhaust?....marks on the shaft of the header wrap?

 

dave

[Klasik-69]

My car is equipped with the Zetec is fuel injected and fitted with manual steering. My steering shaft runs thru the exhaust headers like yours but I have never had any issues with stiffness in the steering. I race on southern tracks with air temps in the mid to upper 90's. The engine never overheats either, goes to and stays at 80 deg C.

[xcarguy]

. . . car got even hotter with extended running without movement.

 

My car is equipped with the Zetec is fuel injected and fitted with manual steering. My steering shaft runs thru the exhaust headers like yours but I have never had any issues with stiffness in the steering. I race on southern tracks with air temps in the mid to upper 90's. The engine never overheats either, goes to and stays at 80 deg C.

 

I wonder if Klasik-69 is on to something here. :rofl: What temp/s are you running when sitting still vs. moving? May be a cooling issue.

[marcos930]

What sort of ball joints are you running on your front suspension. I am willing to bet that sustained running during the test with the wheels pointed straight ahead has resulted in some wear at the straight ahead position. Hence the resistance when you moved it. Have had this happen to me with sustained running on the highway with very few corners. Replaced my lower ball joints, problem solved.

 

Cheers

[Guest Jim Cambon]

I have a Birkin with a Zetec. My steering shaft has a universal joint just outside the headers. Steering effort increases on center on hot days on the street or track. Everything goes back to normal when car cools down. I wonder if the solidly mounted radiator is part of the problem, possibly torquing the chassis and causing the steering rack to bind. Next time I get the problem, I'll try loosening and retightening the radiator mounts, and see if the problem is reduced when hot and recurs when the car is cool. If so, more flexible radiator mounting might be the answer.

Edited August 16, 2017 by Jim Cambon

[Klasik-69]

The steering getting more relaxed after cooling down may be the result of the tires cooling down and not gripping the asphalt. When my Hoosiers are hot, they can pick up anything from the extreme stickiness of the rubber. I've come back with rocks, cigarette butts, bolts, package wrappers, etc going thru the paddock.

 

Another thing that may also contribute is the amount of wheel backspacing, or lack of it, making the wheel pivot beyond the steering spindle's pivot point. Add sticky tires and the problem can be exacerbated.

 

If we're talking about a car with P/S, then I would suspect the pump getting weak which gets worse when the fluid gets hot. Also, a weak P/S pump will cause fluid to get hotter than normal due to the bypass of fluid past the vanes, if a vane pump is used, or past the gerollers of using a geroller type pump. Typically, fluid is good up to 220 deg F. It's also easy enough to check fluid temp with an infrared thermometer.