Proper Tailwheel Steering Springs?

How to keep the Cessna 170 flying and airworthy.

Moderators: GAHorn, Karl Towle, Bruce Fenstermacher

reecewallace
Posts: 165
Joined: Tue Jan 05, 2021 1:34 am

Proper Tailwheel Steering Springs?

Post by reecewallace »

My AME (mechanic in Canada) has advised me I have the incorrect tail wheel steering springs and I should replace them with the proper set up.
IMG_2698.jpg
This is what I'm currently using. Apologies for the poor photos. They are the retractable type springs—I found a picture on Google of the same spring style my 170B has (not my plane).
unnamed.jpg
Is anyone able to advise me on which springs to purchase? Also—do I need to order chains too? I believe my current set up is possibly from past float rigging the way it comes out the bottom of the fuselage??
IMG_2697.jpg
- Reece
1956 Cessna 170b
Nanaimo, BC Canada
User avatar
dstates
Posts: 472
Joined: Sun Jun 30, 2019 5:50 pm

Re: Proper Tailwheel Steering Springs?

Post by dstates »

N1235D - 1951 170A - SN: 20118
User avatar
pdb
Posts: 466
Joined: Tue Apr 23, 2002 3:39 am

Re: Proper Tailwheel Steering Springs?

Post by pdb »

Your mechanic is correct, you do have the wrong springs. Your present springs are known as compression springs and have limited travel.

Worse, those springs can damage your control system as the springs bottom out quickly and transmit too much force to other parts of the rudder control system.
Pete Brown
Anchorage, Alaska
N4563C 1953 170B
http://farm3.staticflickr.com/2366/2527 ... 4e43_b.jpg
reecewallace
Posts: 165
Joined: Tue Jan 05, 2021 1:34 am

Re: Proper Tailwheel Steering Springs?

Post by reecewallace »

dstates wrote:Get these from Univair....

https://www.univair.com/cessna/cessna-1 ... ts-cessna/
Thanks, I'll order these now.
- Reece
1956 Cessna 170b
Nanaimo, BC Canada
reecewallace
Posts: 165
Joined: Tue Jan 05, 2021 1:34 am

Re: Proper Tailwheel Steering Springs?

Post by reecewallace »

pdb wrote:Your mechanic is correct, you do have the wrong springs. Your present springs are known as compression springs and have limited travel.

Worse, those springs can damage your control system as the springs bottom out quickly and transmit too much force to other parts of the rudder control system.
Appreciate this. I'm going to order the springs from Univair as advised above. You're right though—the steering doesn't feel great as is
- Reece
1956 Cessna 170b
Nanaimo, BC Canada
User avatar
GAHorn
Posts: 20968
Joined: Fri Apr 12, 2002 8:45 pm

Re: Proper Tailwheel Steering Springs?

Post by GAHorn »

These are sometimes called “Piper” tailwheel springs... the Scott PN is 3239 and are known as “heavy duty” springs. The current price at Univair as well as at Spruce is criminal.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
User avatar
Bruce Fenstermacher
Posts: 10313
Joined: Tue Apr 23, 2002 11:24 am

Re: Proper Tailwheel Steering Springs?

Post by Bruce Fenstermacher »

GAHorn wrote:These are sometimes called “Piper” tailwheel springs... the Scott PN is 3239 and are known as “heavy duty” springs.
Let us be a little clearer. The springs the OP showed in the first pictures are compression style springs known as Maule springs because they were developed by BD Maule to use with his tail wheels. All but on model of BD's tail wheels, and not very commonly found, has any kind of dampening. A correct set of BD Maule springs will have one with a smaller diameter coil than the other or different compression force. I remember learning the theory being one would only dampen the bounce from the other, not balance the other and continue the bounce. They were/are sold as "shimmy reducing" or "anti shimmy springs". And they may do that for the Maule wheel they were intended. The Scott 3200 and duplicates have internal dampening. That is what the 3 or 5 springs and brass plates are for. As we know an improperly mounted, miss adjusted or worn Scott 3200 will shimmy and naturally owners installed "anti shimmy" springs rather than understand their real issue and fix the real problem.

Scott made 2 different size springs. Small #2134 for "small" aircraft and large #3239 for "larger" aircraft. I've never seen a Scott description for what was a small aircraft and what was a large aircraft. Scott springs of both sizes where used on many different makes of aircraft and so could be labels as Cessna, Piper, Stinson etc. We want the large #3239 springs for all model 170s. There was a period of time when suppliers didn't list the #3239 and I've seen them listed as Piper springs (which they could be) but leading one to think they wouldn't be right for their Cessna.
CAUTION - My forum posts may be worth what you paid for them!

Bruce Fenstermacher, Past President, TIC170A
Email: brucefenster at gmail.com
User avatar
DaveF
Posts: 1516
Joined: Sat Nov 03, 2007 1:44 am

Re: Proper Tailwheel Steering Springs?

Post by DaveF »

Don't waste your energy trying to make the steering work. Just put the pieces and parts together as they're supposed to be, and then get good at using the brakes for steering. I've tried new leaf springs, tight chains, loose chains, three pressure plate springs and five, different kinds of grease, different tire pressures and different tires. Nothing made even the slightest difference in steering performance.
User avatar
ghostflyer
Posts: 1390
Joined: Mon Apr 21, 2008 3:06 am

Re: Proper Tailwheel Steering Springs?

Post by ghostflyer »

This area of the aircraft gets a hammering and I used to have shimmy and all sorts of issues [believe me some of the shimmy issues made your heart jump out of your chest] . I spat the dummy and ordered all new parts from spruce , but with the exception of the tail wheel spring as the angle of the pivot point to the tarmac was correct . I replaced the 3 small springs and wear plate ,bearings , and that “w” spring ,seals etc. I grease it with “aero” boat bearing grease”blue in color”. Before any flight I pump the 2 grease nipples in this tail wheel area with grease . Yes, it’s a bit messy but landing on beaches or rough tracks one has to keep dirt out . BUT, I do not have any shimmy issues at all .plus I have found the pivot bolt /nut has to be torqued correctly . I used the reference from the US army bird dog manual , I couldn’t find any reference any where else. They say tighten until very firm and then slacken off 2 flats of the nut and then split pin . Works perfectly for me . But saying all that George has pointed out I do not have the correct installation of the tail wheel spring . While what he says is totally correct , the way the spring is packed works for me . Tire pressure is always about 45psi. I will be soon fitting a tail wheel tire filled with poly eurathane foam. No air required . [approved soon]. Note.. I have been replacing all springs and wear plates and attach bolts every 500hrs and roll pin also.
Note.. I can not find any reference to use 5 pressure springs on my pressure plate . I only use 3 .
User avatar
GAHorn
Posts: 20968
Joined: Fri Apr 12, 2002 8:45 pm

Re: Proper Tailwheel Steering Springs?

Post by GAHorn »

ghostflyer wrote:This area of the aircraft gets a hammering and I used to have shimmy and all sorts of issues [believe me some of the shimmy issues made your heart jump out of your chest] . I spat the dummy and ordered all new parts from spruce , but with the exception of the tail wheel spring as the angle of the pivot point to the tarmac was correct . I replaced the 3 small springs and wear plate ,bearings , and that “w” spring ,seals etc. I grease it with “aero” boat bearing grease”blue in color”. Before any flight I pump the 2 grease nipples in this tail wheel area with grease . Yes, it’s a bit messy but landing on beaches or rough tracks one has to keep dirt out . BUT, I do not have any shimmy issues at all .plus I have found the pivot bolt /nut has to be torqued correctly . I used the reference from the US army bird dog manual , I couldn’t find any reference any where else. They say tighten until very firm and then slacken off 2 flats of the nut and then split pin . Works perfectly for me . But saying all that George has pointed out I do not have the correct installation of the tail wheel spring . While what he says is totally correct , the way the spring is packed works for me . Tire pressure is always about 45psi. I will be soon fitting a tail wheel tire filled with poly eurathane foam. No air required . [approved soon]. Note.. I have been replacing all springs and wear plates and attach bolts every 500hrs and roll pin also.
Note.. I can not find any reference to use 5 pressure springs on my pressure plate . I only use 3 .
Five pressure-plate springs are used on L-19 and “heavy” aircraft. Only 3 springs are used on 120/140/170 aircraft. What I say is totally correct only in the Southern Hemisphere.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
User avatar
IA DPE
Posts: 208
Joined: Fri Nov 10, 2017 1:46 am

Re: Proper Tailwheel Steering Springs?

Post by IA DPE »

DaveF wrote:Don't waste your energy trying to make the steering work. Just put the pieces and parts together as they're supposed to be, and then get good at using the brakes for steering.
I’ve seen several people post this, and always wondered. For some reason, my ‘55 steers pretty good. Tight turns or strong crosswinds require brakes, but normal taxiing is good, (almost) like a tricycle.

The previous owner was an A&P/IA with seemingly a lot of time on his hands so maybe he really tuned it up. :?:
1955 C170B N2993D s/n 26936
1986 DG-400 N9966C
User avatar
GAHorn
Posts: 20968
Joined: Fri Apr 12, 2002 8:45 pm

Re: Proper Tailwheel Steering Springs?

Post by GAHorn »

The “steerable” tailwheels’ steerability depends on several factors, not to exclude:
1- Weight & Bal ...the amount of weight on the tailwheel can vary quite a bit, not only from plane to plane but from flight to flight.
2- Tailwheel MainSpring-Angle: The caster affects the ability of the tailwheel to rotate or steer because a “negative” caster (king-pin/bolt head FWD) will require the tailwheel to actually LIFT the weight upon the tail landing gear. The “free-space” of reduced-effort is a narrow band, ...It is so much easier to remain within the narrow-angle, the wheel constantly “searches” for that band....and that allows “shimmy”. Positive caster (king-pin/bolt head AFT) will allow better rudder-only steering because it does not require the tailwheel to lift the weight of the airplane to deflect from side-to-side. This forces the wheel to remain within the detents ...so the steering mechanism remains engaged. This keep the turntable/friction-discs clutched...and reduces the tendency to “shimmy”. This might seem counter-intuitive ....nonetheless, incorrect caster is what primarily causes “shimmy”.

The on-line video (produced by one of the tailwheel mfr reps) of how to adjust the tailwheel steering by raising the tailwheel off the ground in the hangar.... is simply wrong, sad to say. They should know better, but it’s an example of how misunderstood this subject is.

(Red words have been edited for correction)
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
User avatar
DaveF
Posts: 1516
Joined: Sat Nov 03, 2007 1:44 am

Re: Proper Tailwheel Steering Springs?

Post by DaveF »

IA DPE wrote:I’ve seen several people post this, and always wondered. For some reason, my ‘55 steers pretty good. Tight turns or strong crosswinds require brakes, but normal taxiing is good, (almost) like a tricycle.
Dang it, now you've gone and done it -- back down the rabbit hole! :lol:
User avatar
Joe Moilanen
Posts: 596
Joined: Sun Dec 28, 2003 5:45 am

Re: Proper Tailwheel Steering Springs?

Post by Joe Moilanen »

GAHorn wrote:The “steerable” tailwheels’ steerability depends on several factors, not to exclude:
1- Weight & Bal ...the amount of weight on the tailwheel can vary quite a bit, not only from plane to plane but from flight to flight.
2- Tailwheel MainSpring-Angle: The caster affects the ability of the tailwheel to rotate or steer because a “positive” caster (king-pin/bolt head FWD) will require the tailwheel to actually LIFT the weight upon the tail landing gear. The “free-space” of reduced-effort is a narrow band, ...It is so much easier to remain within the narrow-angle, the wheel constantly “searches” for that band....and that allows “shimmy”. Negative caster (king-pin/bolt head AFT) will allow better rudder-only steering because it does not require the tailwheel to lift the weight of the airplane to deflect from side-to-side. This forces the wheel to remain within the detents ...so the steering mechanism remains engaged. This keep the turntable/friction-discs clutched...and reduces the tendency to “shimmy”. This might seem counter-intuitive ....nonetheless, incorrect caster is what primarily causes “shimmy”.

The on-line video (produced by one of the tailwheel mfr reps) of how to adjust the tailwheel steering by raising the tailwheel off the ground in the hangar.... is simply wrong, sad to say. They should know better, but it’s an example of how misunderstood this subject is.
Wouldn't "positive" castor mean (king-pin/bolt head AFT) instead of FWD? The bolt would angle forward at it's bottom end if the castor was positive?

Joe
4518C
User avatar
sfarringer
Posts: 309
Joined: Wed Jan 12, 2005 10:49 pm

Re: Proper Tailwheel Steering Springs?

Post by sfarringer »

IA DPE wrote:
DaveF wrote:Don't waste your energy trying to make the steering work. Just put the pieces and parts together as they're supposed to be, and then get good at using the brakes for steering.
I’ve seen several people post this, and always wondered. For some reason, my ‘55 steers pretty good. Tight turns or strong crosswinds require brakes, but normal taxiing is good, (almost) like a tricycle.

The previous owner was an A&P/IA with seemingly a lot of time on his hands so maybe he really tuned it up. :?:
I agree! I always thought the tailwheel steering of my 170 was pretty good! Differential braking is necessary for tight turns and strong wind, but not normal taxiing.
I guess my standards aren't high enough!
Ragwing S/N 18073
Post Reply