Rear subframe removal procedure

[1999marg]

Ok the time has arrived to upgrade my IRS bushings. I have the car safely supported. Everything that needs to be removed is (calipers, antilock brake sensors, parking brake cables etc.). The car currently has 16.5” clearance from the lowest point on the inboard LCA to the floor in my garage. My jack in its lowest position is about 3.5” tall. That leaves 13” max to relax the springs. Is that enough?

If that is enough I am still concerned with the arc that my floor jack will follow. I will have to drop the rear subframe on to jack stands then reposition the jack once or twice to avoid having the subframe slid off the jack as it travels through it arc. This makes me cautious since the springs will be under considerable load as I do this.

I could purchase a Harbor Freight 450# low lift scissor style transmission jack for this step. It traverses straight up and down. The Harbor Freight tools maximum lift height is 23.25” and its min lift height is 7.5”. This only leaves 16” of travel to relax the springs. I would have to raise the car ~3 inches to do this. That is pretty darn high.

This leads me to my next question can I simply remove the springs before removing the sub frame? I have 13” to the bottom of the LCA at each rear knuckle bolt point. That would give me 10” to relax the spring. Is that enough? If it is i could simply do the following:

• Remove the lower bolt on the anti-roll bar at each LCA
• Install the jack under the rear knuckle
• Remove the upper and lower bolts holding the knuckle in place
• Remove the knuckle
• Slowly relax the jack on the LCA until the spring is ready to be removed by hand


The thinking is once the springs are out I can simply loosen all four sub frame bolts, then lower the sub frame rear first until it is on the floor than remove both front bolts. Plus the hunk of metal will be a lot easier to handle. Diff and halfshafts are already out of the car.

I would prefer to remove the springs first. What do you think?

All the best
Mike

 

[e010740]

Springs need to come out first. Check out the FTBR website. (Full Tilt Boogie Racing) There is video on how to do this proceedure. Hopefully you are using their bushing set. Best one around IMO.

 

[P49Y-CY]

no, i think that you had the right idea first. imo it is much much easier to let the rear of the subframe swing down instead of trying to remove the springs any other way. and even the way you descibed probably wouldnt work and would be dangerous, you would still need a coil spring compressor if you wanted to do it that way.

but forget all that and just let the rear of the subframe swing down. soooo much easier - i have done it both ways. i dont think you wiil even need that harbor freight jack. best of luck with it :beer:

 

[1999marg]

P49Y-CY, agreed taking the springs out is not the way to go. I released the sway bar link at the LCA. Plan is to slowly lower the rear subframe. I did some trig and I think I have enough space. Make sure you have a 15mm racheting box wrench when removing the sway bar end links at the LCA. I did not and that has been the hardest part so far.

cheers

Mike

 

[BobEFFC]

It's been a long time since I've been here. Hello

Umm my first thought is you're making more of this than you need to. I stick a floor jack under what seems to be the middle of the subframe, jack it up a little, take out the mounting bolts and then lower the whole thing onto the floor and wheel it out while it's still on the floor jack. It's not really that heavy. I've also taken the springs out one at a time with the jack under the control arm to release the tension. It's only the first few inches that are under a lot of tension.

Just out of curiosity, why did you take the differential out of the subframe before you took it out of the car?

 

[1999marg]

LOL ……You’re right I do tend to overanalyze first time procedures whenever I am working with large coil springs. Last thing I need is the spring flying through the gypsum garage wall and whizzing by my wife’s head in the laundry room.

At first glance I could not find a write up or video that definitively demonstrated how the spring pressure was safely released. At e010740 suggestion I reviewed the FTB installation video one more time and it looks like 95% of the spring pressure is released when you allow the LCA’s to slowly pivot down. The rest appears to happen when you lower the subframe.

I just wanted to make sure I had enough height because it would be a pain if my jack bottomed out while rotating the rear subframe section down and the spring pressure did not fully released. Then a 10 minute job turns into a PIA.

As for the differential, I removed the diff a few weeks ago to replace the seals and bearings plus install a new Ford Racing cover. Getting the diff in and out of the cradle is relatively painless. I may completely assemble the subframe prior to reinstalling it or keep the diff and knuckles out to keep the weight down. Sounds like you just re-installed the whole assembly as a unit.

Thank you for the feedback.

Buona Pasqua!

Mike

 

[jrgoffin]

Search much? Maximum Motorsports has instructions on their site for just about everything. Then again, there is always a Ford service manual.

Installation Instructions : Maximum Motorsports, the Latemodel Mustang Performance Suspension Leader!

 

[1999marg]

Boom stick! Double checked everything having a cup of tea and in 15 minutes it should be on the ground.

Thanks

 

[1999marg]

If I had the Harbor Freight jack or if the diff was still in the subframe it would have been a 2 min job. It took me less than 10 by myself with two floor jacks. Finished the rear diff bushing in 5 minutes. Start the upper and lower control arms tomorrow. Dam undercoating is on everything!

Cheers
Mike

 

[Brutal Metal]

a black 03 vert came in the shop this morning with boxes of IRS bushings, he said he wants ALL of them replaced, what a major PITA for my boy Steve, he was struggling went through lots of propane for the torch ...Can't be fun on jack stands after witnessing this procedure on a number of ocasions from a lift...

 

[1999marg]

Honestly, just a small amount of heat is needed. I finished all four subframe bushings heating the steel to 300 degrees (I have a Flir IR camera). Once the steel was heated ithe bushings came out as fast as you could turn the wrench. Very little resistance once the initial bond is broken.

The UCA bushings came off easily with a visegrip. Hardest part so far is cleaning the undercoating off of the old subframe and lca's. I am just going to have the LCA's sandblasted.

 

[ac427cobra]

Here is a video we shot in our shop for a 'how to' to remove the IRS subframe from the chassis:

FTBR IRS Removal - YouTube

:thumbsup::coolman::beer:

 

[DC97Cobra]

Dropping the IRS was a lot easier than I expected. When I lowered mine out of the car, I tossed a sand bag on the jack to give the diff some protection and lowered it down. The sand molded to the IRS and helped keep it somewhat balanced.

Hoping to do this again next winter once I have finished rebuilding the original IRS out of the car.