Front spring over axle question

[bcowanwheels]

Front spring over axle Modification

I,am about to start on another (stock) d60 M715 front axle referb and I need to do the spring over axle modification. I know the tie rod and drag link needs to be moved to top of hi-steer arms which my machineist is doing now but i have a question for the fellas who have (first hand experience ONLY) that have done this to stock m715 ft. axles as to what they have set there pinion angle to ? do you keep iy same as when its mounted spring under ? seems to me it needs to be increased slightly to go along with the different mounting position. i,am going to measure a chevy cucv d60 and see what that is also as its soa mounted. all help is appreciated.
bob

 

[jtrojan715]

haven't done one on a 715 but on a land cruiser. pinion angle will change the caster angle, unless you cut and turn the knuckles. lot of info on line look up SOA (spring over axle). look at toyota axles because the knuckles are similar both are closed. good luck

 

[bcowanwheels]

Thanks, after thinking about this most of last night i realized that so i,am going to just move spring pads to the top and keep pinion angle as as stock. Will have pic's soon
regards
bob

 

[quickfarms]

That is the same for any straight axle

 

[spicergear]

For the sake of simplicity and steering shimmies...I've relocated the pads to the top of the axle. If memory serves...one side ends up half on the diff casting and the other side of the mount on the axle tube. Double check clearance when the suspension is cycled down to full droop on the passenger's side to see if you have enough clearance of the driveshaft through the crossmember in front of the T-case.

 

[bcowanwheels]

Doing stock m715 d60 axle tom, just a matter of moving the spring pads from bottom to top.

 

[spicergear]

I did a later model open knuckle 60 and the one perch ended up half way on the casting. If that thing will ever go offroad, check that front driveshaft clearance at the crossmember.

 

[bcowanwheels]

the m715 axle is completely different than a modern d60 in the way it mounts by the diff.

 

[Barrman]

BOB, Tom is talking about the opening in the transmission cross member that the front drive shaft goes through. He is wanting you to make sure that the shaft doesn't hit the cross member at full droop.

For your original question. Caster is more important than pinion angle for street driving with lock out hubs installed, while pinion angle is more important than Caster for off road. 6°-8° of caster is about what you want for a very steady, return to center drive without death wobble. Above 8° and death wobble will be more likely. Below 6° and you will never see death wobble. It will feel like you are driving on ice all the time too.

What is the intended purpose of the truck?

 

[bcowanwheels]

truck will mainly be for snow,off roading and light street use. i,am doing a th400/np205 t-case in it so no worries about the trans x-member. its one of my bobber trucks, a little rough but plenty good for a work-play time off road truck. i live on top of a big hill and when it snows theres no driving up my drive way so in the fall i can chain up the tires and leave it till spring so i can get home also i can play on te trails and on roads when its snowy also pull folk out of ditches. i,ll have a full post on it in a couple days. the truck is burried and i have to move 4 m715's just to get to it. Ive already done the shackle/ front rear spring mount flip on the rear. it looks like a dragster now with the rear end jacked up and ft. down. LOL

 

[Barrman]

Now I get it. You are even going to have room for dual exhaust all the way back to the fuel tank without cutting anything.

I remember Lee going through the entire front pinion angle research and agonizing over it. He ended up trying to get within 2° of the front tcase flange angle. You knew that truck well and how it drove. I never heard about any front ujoint issues. Did it have any?

 

[bcowanwheels]

LEE'S TRUCK was very nicely built. when i drove it it had no issues i noticed but then i never had it in 4wd. on the road however it drove like a car..... I believe moving the axle under the springs will add length to the drive shaft and compinsate for the slight increase in pinion angle. going to pull the axle today, also installing n.o.s front springs and shackles.

 

[bcowanwheels]

well on my way to this modification. got my hi-steer arms reemed to correct "top" mounting location along with the bigger tierod ends. I also found and bought the correct dropped pittman arm for adding power steering/ hydro assist. i also installed new front springs and new shackles along with new grade #9 mounting bolts. lastly I reversed the spring center bolt to opposite side as spring mount on axle is now on top instead of the bottom of the axle. I,ve got some pictures of all this for you-all. notice on the springs there is a front and rear on these, the rear has serration in the bushing the front bushings is smooth on the outer sides where it contacts the shackles.also note how the spring bushing have fatiged and when this happens you,ve lost all your agignment on your front end. common problem with original springs. also notic how much bigger the holes are in the hi-steer arms compared to original size as in pittmen arm.
enjoy
bob

 

[calpyro]

I,am about to start on another (stock) d60 M715 front axle referb and I need to do the spring over axle modification. I know the tie rod and drag link needs to be moved to top of hi-steer arms which my machineist is doing now but i have a question for the fellas who have (first hand experience ONLY) that have done this to stock m715 ft. axles as to what they have set there pinion angle to ? do you keep iy same as when its mounted spring under ? seems to me it needs to be increased slightly to go along with the different mounting position. i,am going to measure a chevy cucv d60 and see what that is also as its soa mounted. all help is appreciated.
bob

I kept the stock angle and it worked nice. I had to modify the cross member for the front drive shaft to move up and down. I welded a "U" out of 1/4" flat stock on to the cross member.
Also, my truck's U joints had a binding issue that I fixed with this: Tom Wood's Custom Drive Shafts - Tom Woods Custom Drive Shafts Custom Driveshafts Specialist

 

[kvflyer]

Bob,

I am back in the US now. At your suggestion, I bought new springs and have them with the truck in Florida. My original springs have tired bushings as well. I am hoping that with a new old stock steering box, new coupling shaft and new springs, I can eliminate the shimmy that I have with the present setup.

Looking good and good luck. I will be following this thread!

 

[bcowanwheels]

Don, get some new front shackles also. Hope your enjoyed down under !

 

[bcowanwheels]

Thanks calpyro

 

[kvflyer]

Don, get some new front shackles also. Hope your enjoyed down under !

Thanks Bob, I did.

I did enjoy watching my grandson for three weeks. Hope you are doing well.

Don