Advice on rear Leaf Spring / 71 351C 4V

7173Mustangs.com

Help Support 7173Mustangs.com:

Joined
May 31, 2020
Messages
257
Reaction score
125
Location
Alberta, Canada
My Car
1972 Mach 1
351C 4V - C6
Blue with Blue interior
Nice, thats what I will probably get. When I am under doing the springs I think Im going to take the steel brush to the axle housing and then give it a coat of paint. And likely do the same for the underside of the car and find some rust convertor paint. Just got it back from the exhaust shop and its looking much better for clearance, and likely get some more back when the new springs go in. Excited to see what it feels like with new shocks and springs. 

 
Joined
Sep 12, 2015
Messages
6,264
Reaction score
1,253
Location
SW Ontario
My Car
1971 Mustang Mach 1, M code, 4 speed.
Nice, thats what I will probably get. When I am under doing the springs I think Im going to take the steel brush to the axle housing and then give it a coat of paint. And likely do the same for the underside of the car and find some rust convertor paint. Just got it back from the exhaust shop and its looking much better for clearance, and likely get some more back when the new springs go in. Excited to see what it feels like with new shocks and springs. 
When you get that far into the rear end, it's not hard to remove the axle completely. (The hard part was unclipping the parking brake cables, but I found a small gear clamp worked to compress the clips. I also did a complete brake replacement while at it). That way you can do a bang up job of cleaning and painting. Just need a couple of good (6 ton) jack stands and a good floor jack, see pic. When I did mine, there was very little rust (car is totally rust free) but I did use "Rust Check" spray rust converter which you can buy at Canadian Tire or similar. I have found this product excellent as it does what it claims and is an excellent primer. Then I used Eastwood's Chassis Black and did the center section in red oxide primer with clear coat over it. If you do your floors, I'd use the Rust Check as well but I would not use "rust paint".

Future under car projects; SS fuel lines with fuel injector rubber tube where necessary (ethanol resistant). New brake lines, ss or good quality steel, your choice. Rebuild the drive shaft. The list goes on........... and on!

As for the pics of the finished axle, lost, I'll have to re-take and post later. Added

Note 1; use blocks under the spring mounts to support while you're working on it.

Note 2; watch Eaton video on U bolt torque at start of this thread.

IMG_1042.JPG

IMG_1043 (2).JPG

IMG_1462.JPG

IMG_1465.JPG

 
Last edited by a moderator:
Joined
Jan 7, 2015
Messages
8,032
Reaction score
505
Location
Western North Carolina
My Car
Multiple Mustangs!
What I notice about having gas filled shocks is that the ride is very harsh compared to just a hydraulic valved body shock. On my 73 the PO put gas shocks on when you hit a big bump it is like the front is going to break off and never had that with hydraulic. It does handle good just a very harsh ride. 

 
Joined
Aug 14, 2014
Messages
3,771
Reaction score
708
Location
Madison, WI
My Car
1971 M-Code Mach 1 w/408C stroker
What I notice about having gas filled shocks is that the ride is very harsh compared to just a hydraulic valved body shock. On my 73 the PO put gas shocks on when you hit a big bump it is like the front is going to break off and never had that with hydraulic. It does handle good just a very harsh ride. 
That is not uncommon. You have to select the spring to go with the gas shocks. Because gas shocks are pressurized they actually add to the spring rate. 

 
Joined
Sep 12, 2015
Messages
6,264
Reaction score
1,253
Location
SW Ontario
My Car
1971 Mustang Mach 1, M code, 4 speed.
I think in another post, maybe jpaz's, I mentioned I have ordered a new set of Eaton Boss 351 rear springs. I also mentioned that the shocks may get replaced next year  as yes, they are a bit on the harsh side if I hit a large bump. Shocks are not hard to change, just a pita. 

in my case, the KYB Gas-a-Just shocks were supplied in the front end kit I bought, so obviously I used the same in the rear. I do agree, they are not the best, but not the worst either. A Mach 1 shouldn't ride like a Lincoln.

 
Joined
Sep 12, 2015
Messages
6,264
Reaction score
1,253
Location
SW Ontario
My Car
1971 Mustang Mach 1, M code, 4 speed.
So I have two threads going with a similar theme. I seem to have talked about switching to Eaton Detroit Springs Boss 351 leaf springs in this thread as well as "An interesting and informative video from Eaton Detroit Springs". I will continue posting about the install of the B351 springs in that thread from now on. Sorry if it caused any confusion.

 
Last edited by a moderator:
Top