Merc acting like a whale

[FlatheadTed]

Working on this 39 Merc for a customer he just changed over to radial tyres but it drives like a whale 50MPH about the limit ,it darts or wonders of to any side left or right .I have tried various tyre pressures .It has no sway bar which I thought it should have ,the shocks seem ok but have not hand worked the arms , its got caster and alignment and all joints seem ok .Thanks someone may have experienced this .Ted

[39topless]

Have you checked the steering box?

[fordor41]

sway bar would help on a curve or curvy road. If the road is flat the sway bar is basically out of the equation. I'd check for correct alignment and excess "play" in the steering box.
looks like some kind of incorrect D.S. shock link. I have basically the same stock set-up on my '41 Ford and it travels down the road straight and true at any speed. Too much shock (rotarys are adjustable) or bound up suspension components can cause the front of the car to follow any dips in the road instead of just the suspension. I assume there are radials all the way around.

[FlatheadTed]

,Radials all round ,The wheel aliment appears to be correct ,steering box has no play and is very smooth .The body on pushing it appears solid not rolly Polly .

[Talkwrench]

King pins? Adjusted the alignment to suit radials? tyre pressure?

My 56 does tend to wonder a bit with radials the only thing that's not 100% on that is the steering box..

[FlatheadTed]

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This is towed in I/8 ,the back of the car is lower than the front ,possibly losing some caster??.He had 45PSI in the tyres and I dropped it to 37 it made it worse .Maybe springs need re doing ,?? Ted

[fordor41]

Originally Posted by FlatheadTed

This is towed in I/8 ,the back of the car is lower than the front ,possibly losing some caster??.He had 45PSI in the tyres and I dropped it to 37 it made it worse .Maybe springs need re doing ,?? Ted

wow. 45 PSI. I'd shoot for 32-35 PSI all way around.

[40 Deluxe]

Find a similar car with bias ply tires in good shape and do a temporary swap (drive both cars w/each other's tires).

[FlatheadTed]

Yeah might have to do that ,he had bias plys on it ,but he cannot remember how it went ,??Ted

[Ross F-1]

Originally Posted by fordor41

wow. 45 PSI. I'd shoot for 32-35 PSI all way around.

Ditto!

1/8" toe-in is quite a bit, with radials you usually want to be just barely toe'd in.

[RalphG]

Originally Posted by fordor41

wow. 45 PSI. I'd shoot for 32-35 PSI all way around.

1953 Ford manual states 24 psi front and 21 rear.

[Phil Gillespie]

On a 38 PU I am running 185 75R x 16C on the front and 205 R x 16C on the back. Running 35 to 36psi.it drives straight and true. Also fitted with telescopic hydr shocks on the front.
Too wide a radial tyre on the front can play havoc.
Phil NZ

[34PKUP]

Originally Posted by RalphG

1953 Ford manual states 24 psi front and 21 rear.

Truly amazing! Didn't realize that '53 Fords had radial tires?

[Bertha]

Originally Posted by 34PKUP

Truly amazing! Didn't realize that '53 Merc's had radial tires?

I didn't think they did either....I tried radials on 'Bertha' when we first her.

Handled....not so good.

Back to OEM....much better with a modern bias ply.

Another reason I went <back...

....The OEM wheels may not be up to the added radial stress.

Bob

[Tom Walker]

Wheel bearings loose?

[Vic Piano]

I run radial tires on several Flatheads,I keep the pressure at 40psi on all of them. My '39 CS has 6.00x16 radials on the OEM wheels (running without tubes), my '47 Ford Convertible is running tubeless radials on 15 inch Merc wheels and both my '51 F-1 and '53 F-100 Panel Truck are running tubeless radials on OEM 15 inch wheels. I have not experienced and degradation in performance as a result of running radial tires, to the contrary, the ride and handling has improved on each vehicle.

[scicala]

Originally Posted by 34PKUP

Truly amazing! Didn't realize that '53 Fords had radial tires?

SA


Sal

[RalphG]

Originally Posted by scicala

SA


Sal

Of course the manual recommendations were for the tires of the day (bias ply) but it is a number for reference. I'm running radials on the 52 Merc. I find 30 pounds pressure rides pretty hard on gravel roads and you feel every pebble. I don't recall that on bias ply tires but it has been a long time .
The Merc runs straight as fast as I've driven it so far. No speedometer working so I can only guess. These are well used P235x70s up front and P215x75s on rear.

[flathead4rd]

When I put radials on my 50 Ford it wandered left and right. I found that the alignment specs for radials are different than the ones for bias ply tires. Got the new specs from JAMCO because I'm running their front disc brake conversion on my car. Made a world of difference along with a slight increase in tire pressure. I run 36 PSI. I've had this car at slightly over 100 MPH (no not on a local street, was on the track at Michigan International Speedway) and no problems of any kind. Oh! and I still run the original flathead with upgrades of course. I'll look through my papers and see if I can find the recommended alignment specs and post them here.

[FlatheadTed]

Ok, thanks so far to all who contributed ,look forward to the aliment specs .Ted