Ross M38/A1 compatibility

4x4M38 · Post by **4x4M38** » Thu Sep 28, 2017 5:26 am

The M38 and A1 apparently have different Ross steering box assemblies.

Can they be interchanged between vehicles?

Thanks,

oilleaker1 · Post by **oilleaker1** » Thu Sep 28, 2017 5:37 am

The A1 column is a bit longer and would provide more dunlap disease clearance!

I do not know if the frame bolt pattern is the same. Other than that, I would think it would work. John

Xamon · Post by **Xamon** » Thu Sep 28, 2017 6:02 am

They also have a different ratio, I do not remember which is which but one takes fewer turns of the wheel for full travel. It has been discussed before and yes they can be used on either vehicle.

4x4M38 · Post by **4x4M38** » Thu Sep 28, 2017 6:19 am

Thanks Guys.

I have an opportunity to buy an A1 takeoff assembly for 25 bucks.

My M38 box has to be trashed. I have not pulled it or disassembled
yet but I've got 1/2" vertical deflection of the sector shaft when I push and pull it at the drag link.

It sounds like not only the bearings and sector shaft are toast, but the case side as well. The horn button has been gone for a very long time, and I suspect there is nothing left in the case but rust. It makes a $&% of a sound when you turn the wheel.

I need to go look at it. One fuzzy photo showed the cover side an it looks like there is damage to the preload screw/nut area.

Thanks again.

Post by **wesk** » Thu Sep 28, 2017 9:42 am

The A1 box has the faster ratio and is less forgiving when jerked too hard especially with any slop in the front suspension.

4x4M38 · Post by **4x4M38** » Thu Sep 28, 2017 10:03 am

Thanks Wes.

The box is the last thing I need to rebuild in the steering assembly before I look at the knuckles, though I did give them the side to side and up and down wheel shake test, and had no looseness.

That was after I rebuilt the drag link, bell crank, replaced both tie rods and installed new ends all around. Prior to that I could turn the wheel 180 degrees and nothing happened up front......

With the amount of grease or oilly crud I found in the right front drum, I'm hoping to find that the excess lube kept the knuckle assemblies from suffering the same fate as some of their related parts.....

One can only hope.

4x4M38 · Post by **4x4M38** » Fri Oct 06, 2017 2:14 pm

Are the bolt patterns the same?

Tks,

oilleaker1 · Post by **oilleaker1** » Fri Oct 06, 2017 3:00 pm

Expect the worse. The rollers have a bad habit of gouging recesses in the race and rust right there because the don't move much at all like a wheel bearing does. That's my experience.

4x4M38 · Post by **4x4M38** » Fri Oct 06, 2017 4:16 pm

Hi John,
I'm sure no matter what shape the A1 I found is mine is in much
worse shape. I'm sure that water has been into the tube as the button
has been gone for a long time. It makes a terrible sound when the
wheel is turned from side to side and I have about 1/2" vertical
deflection of the sector shaft. Without tearing it down I'm not sure
the shaft bearings have gone to the point of the housing being damaged.

I'm going to grab the A1 and take a look, and see where that takes me.

Thanks!

Post by **wesk** » Fri Oct 06, 2017 10:48 pm

Well the used A1 will bolt in the same holes. Most likely the A1 box, if it is rebuildable, (You haven't determined that yet) will need rebuilding as well and all you'll need to do is buy a new worm gear that is the correct ration for your M38.

4x4M38 · Post by **4x4M38** » Sat Oct 07, 2017 7:45 am

Yes I plan on rebuilding the better of the two.

Thanks for the worm gear tip!

Post by **wesk** » Sat Oct 07, 2017 10:55 am

One other note: The A1 box is much beefier size-wise then the M38 box so expect a more crowded space between it and the exhaust and longer bolts.

4x4M38 · Post by **4x4M38** » Wed Nov 01, 2017 9:31 am

I've been reading through older posts on steering boxes and horn rods, etc.

I ran across an older post regarding the different ratios in the M38 and A1 boxes. As I understand it the A1 has higher numbers or a higher ratio in the gearing. This would tell me if I remember my hot rod days, that it takes fewer turns of the wheel to get the tires to turn.One post I was reading said just the opposite, with some notations.

I am guessing this was incorrect, and the latest one here is correct.

I understand the higher ratio turns the wheels faster, but given everything forward of the Pittman arm on both the M38 and A1 are identical except for maybe beefier tie rods and a different mount for the bell crank, why would the later, higher ratio box be any less safe in the M38?

More horsepower would not seem to be a positive thing with a higher ratio.
Same wheelbase, same wheel and tire diameters, etc...

Am I missing something?

Just trying to understand.

Thanks.

Post by **wesk** » Wed Nov 01, 2017 8:58 pm

I think you are confusing the terms. Hi ratio vs Lo ratio or Slower ratio vs Faster ratio.

Hi ratio = slower front wheel reaction to the steering wheel movement. More turns of the steering wheel for less movement of the front wheels.

Lo ratio = faster front wheel reaction to the steering wheel movement. Less turns of the steering wheel for more movement of the front wheels.

When comparing M38 to M38A1 front suspension They are not the same The A1 has reversed front spring shackles and the two jeeps have a different spring count and spring rate. The A1 also has 1" longer wheelbase. But more importantly the M38A1 with 12 more HP was usually a Faster jeep as well as a heavier jeep. It was the combination of these M38A1 traits that led to using a slower ratio (higher numerically)

Steering ratios are:

Early M38 = 15.4-13.5-15.4:1
Late M38 = 14-12-14:1
M38A1 = 19-17-10:1

The real danger in swapping ratios between the jeeps is putting the faster steering M38 gear boxes in the M38A1 not vs versa.

4x4M38 · Post by **4x4M38** » Wed Nov 01, 2017 9:29 pm

That explains everything.

Thanks Wes.

Ross M38/A1 compatibility

Ross M38/A1 compatibility

steering box ratios