914 vs 911 steering rack

[Jim2]

I'm harvesting the drivetrain and suspension from a six conversion car with five lug suspension over to a 72 914. I have some spare 911 steering racks and the donor car has turbo tie rods which I can move over to the car I'm building but I was wondering if there is any reason to use a 911 rack, this on the assumption they interchange with the 914 rack. Has anybody got some insight to the difference? I noticed the rack casting is pn 914xxxx so clearly something is different.

[Jim2]

I just found a couple old threads discussing virtues of the 911 rack vs the 914 unit and it ends up that they are the same with no discernible difference aside from the input steering shaft which bolts to the rubber donut.

[DonNewton]

Ding!, Ding!, Ding! What he said.

[Clay Perrine]

There were some 911s with a quicker rack ratio, but they are few and far between. And expensive too.

Otherwise all the racks are the same.

Clay

[Dave at Pelican Parts]

I didn't know that! Any idea what 911s they were from?

--DD

[Evan Fullerton]

Rumor is early SWB cars with the steering damper have a faster ratio. I have no direct 1st hand knowledge though.

Quaife also makes a quicker ratio retrofit. I put one in a 911 rack and the whole thing into a 914. Works great for autocross...... but add noticeably to the steering effort as you would expect. With a LOT of caster it's pretty heavy even with only 205 Hoosiers.

[Clay Perrine]

Originally Posted by Dave at Pelican Parts

I didn't know that! Any idea what 911s they were from?

--DD

Nope.. I actually saw one at Okteenerfest in 2019. Somebody else won it in the door prizes.

[oldie44]

According to the Haynes 911 Manual, the change was made with the 1969 model year. SWB rack ratio was 16.5:1, LWB was 17.78:1.

[Jim2]

There is literature floating about which says 930s had a 2.5 rack but after owning four of them I only had 3.0 turns. On one of our forums here I did see someone mention the 2.5 racks came only with very early 930s. I have no idea if there is any truth to this.

[Ed911S]

I have tested many steering racks from road 911s of the 80s, 70s and one with damper mount (67 and earlier). I measured movement of the rack per single revolution of the pinion, all the racks moved 55mm. They may have different crank to crank revolutions which could mean a different number of teeth on the rack but they all moved 55mm per revolution.

Am I missing something?

[Jim2]

Originally Posted by Ed911S

I have tested many steering racks from road 911s of the 80s, 70s and one with damper mount (67 and earlier). I measured movement of the rack per single revolution of the pinion, all the racks moved 55mm. They may have different crank to crank revolutions which could mean a different number of teeth on the rack but they all moved 55mm per revolution.

Am I missing something?

You're not missing anything. May well be as you say, there is only one ratio. But if a rack housing body were longer or the rack itself shorter then this could be responsible for the 2.5 number floating about.

[fetus]

There is an early rack with steel cross member like a 914 and the later lighter aluminum cross member. I heard stories the aluminum one flexes on the track. Besides weight, the aluminum cross member supports an under body non adjustable sway bar up to 22mm. The aluminum cross member also has holes for a fuel pump.

[roblav]

SWB 911s and 912s all have a different rack with quicker ratio. Data located in factory manual.