Drivetrain How to fix driveshaft rubbing on the floor pan?

BlakeusMaximus · Feb 15, 2023

The tears are concerning though

General karthief · Feb 15, 2023

Give us a shot of the rear axle in the car

AeroCoupe · Feb 15, 2023

Those are the correct springs. Just wanted to make sure they did not miss box a set or something.

The shorter pinion snubber is to allow for additional suspension travel which should not be an issue as I have the same snubber on my car. I have a T5 with the factory double hump cross member with the Prothane 7-1604-BL transmission mount. Again, the same stuff I ran with these springs on my Coupe.

I removed the dog bone weight when I installed the FMS aluminum shaft and it has no play in what you have going in rubbing wise.

The Stifflers transmission cross member is a really nice piece and well engineered. It does not allow for moving the transmission up and down so you would have to shim just like the stock cross member. Have you checked the angle of the transmission and the angle of the pinion? With the stock suspension (read rubber bushing LCA's and UCA's) Ford set the pinion angle 3 to 4 degrees below the transmission output shaft angle because of axle wind up allowed by the stock rubber bushings in the stock UCA's and LCA's (quoted from Maximum Motorsports torque arm installation instructions). I read back through your other thread and this one and didn't see anything mentioned about control arms. Are the ones on the car stock?

The reason I ask is I am seeing some rubbing on the front side of the axle housing directly behind the H&R springs (picture in Post #19). This is not normal at all. If the bushings in any of the four control arms are bad then your pinion angle it going to go all over the place and the rear end will move all kinds of funky. IF they are all stock then you could very well have bushing issues that is causing some really unpredictable drive train geometry which could account for the DS contact.

If all of the bushings are in good order then just download the TREMEC Toolbox App and it has a pinion angle finder in it which will get you close enough.

https://www.tremec.com/menu/tremec-toolbox-app/

AnthonyA1234 · Feb 15, 2023

General karthief said:
Give us a shot of the rear axle in the car

Here’s some pics

AeroCoupe said:
Those are the correct springs. Just wanted to make sure they did not miss box a set or something.

The shorter pinion snubber is to allow for additional suspension travel which should not be an issue as I have the same snubber on my car. I have a T5 with the factory double hump cross member with the Prothane 7-1604-BL transmission mount. Again, the same stuff I ran with these springs on my Coupe.

I removed the dog bone weight when I installed the FMS aluminum shaft and it has no play in what you have going in rubbing wise.

The Stifflers transmission cross member is a really nice piece and well engineered. It does not allow for moving the transmission up and down so you would have to shim just like the stock cross member. Have you checked the angle of the transmission and the angle of the pinion? With the stock suspension (read rubber bushing LCA's and UCA's) Ford set the pinion angle 3 to 4 degrees below the transmission output shaft angle because of axle wind up allowed by the stock rubber bushings in the stock UCA's and LCA's (quoted from Maximum Motorsports torque arm installation instructions). I read back through your other thread and this one and didn't see anything mentioned about control arms. Are the ones on the car stock?

The reason I ask is I am seeing some rubbing on the front side of the axle housing directly behind the H&R springs (picture in Post #19). This is not normal at all. If the bushings in any of the four control arms are bad then your pinion angle it going to go all over the place and the rear end will move all kinds of funky. IF they are all stock then you could very well have bushing issues that is causing some really unpredictable drive train geometry which could account for the DS contact.

If all of the bushings are in good order then just download the TREMEC Toolbox App and it has a pinion angle finder in it which will get you close enough.

https://www.tremec.com/menu/tremec-toolbox-app/

Good eye! Yes all of the control arms are stock so this very well could be part of the issue here. I’m thinking I’ll install the MM upper and lower control arms.

I’m thinking I should get the adjustable LCA’s so that worst case scenario if the DS is still rubbing I could just raise the rear up a bit. Would that work?

AeroCoupe · Feb 15, 2023

Second to last picture. The UCA bushings that are pressed into the rear end are destroyed. Get some Moog units and replace the old ones.

If you can swing the new control arms you won’t regret it. My guess is the remaining six bushings in the rock control arms are in bad shape as well. This is most likely the source of your problems.

AnthonyA1234 · Feb 15, 2023

AeroCoupe said:
Second to last picture. The UCA bushings that are pressed into the rear end are destroyed. Get some Moog units and replace the old ones.

If you can swing the new control arms you won’t regret it. My guess is the remaining six bushings in the rock control arms are in bad shape as well. This is most likely the source of your problems.

Yea I thought that one looked bad. Well that’s good to know. Yea I’ll most likely just get new control arms.

Would raising the adjustable LCA’s even give me more driveshaft clearance or is that not how that works. I’m wondering if I should just save my money and get the non adjustable ones but at the same time if these new control arms don’t solve my problem it’d be nice to just raise up the rear some.

AeroCoupe · Feb 15, 2023

Your call. Without coil overs they could be helpful for sure.

Fix the suspension issues and get the structural welded up and go from there.

AnthonyA1234 · Feb 16, 2023

What’s a good paint you guys recommend for painting over bare metal parts or just for cleaning up the undercarriage? I wanna spray some paint over the floor where it’s been rubbing 1 to keep it from rusting and 2 to see if it rubs again.

AeroCoupe · Feb 16, 2023

So I would just use any paint I had in the garage to check for rubbing. Once you have the problem fixed and you make the repairs then you will need to prep the metal for an etching primer then hit it with a semi-flat black. I usually use a degreaser followed by a good scrubbing with Dawn dish washing soap as it strips any grease and wax. Get it good and dry then hit it with the self etching primer and top coat with a semi-flat black. Cannot stress that prep is 80% of how well the paint will hold and prevent any rust in the future.

If you have some light surface rust you can use Krylon Rust Converter and that will create a paintable surface.

Mustang5L5 · Feb 16, 2023

Those upper bushings on the control arms are shot like previously said.

What is likely happening is that under load, the front of the differential is lifting as the tires push the car forward and the rear squats. That causes the driveshaft end near the diff to lift higher in the transmission tunnel, creating your issue.

Likely, fixing your bushing issues will solve the problem, although to do need to address the cracks in the floor.

AnthonyA1234 · Feb 16, 2023

Mustang5L5 said:
Those upper bushings on the control arms are shot like previously said.

What is likely happening is that under load, the front of the differential is lifting as the tires push the car forward and the rear squats. That causes the driveshaft end near the diff to lift higher in the transmission tunnel, creating your issue.

Likely, fixing your bushing issues will solve the problem, although to do need to address the cracks in the floor.

Sounds good. I have some body/paint work coming up for the car soon so I’ll drive with the old driveshaft for now so I don’t mess up my brand new one any more than it already has. Then once I get it back I’ll throw those MM control arms on it.

90sickfox · Feb 16, 2023

That transmission mount could still be too tall.

When you do the upper control arms check the mounting area ( at the body for cracks. This would actually be a good time to get torque box reinforcement plates installed.

I had cracks like that in my convertible. I drilled holes in the ends of the cracks. It stops them from spreading. I welded all of them up after that. My upper and lower torque boxes also had cracks that needed attention. It's very common in convertibles that have been driven hard.

AeroCoupe · Feb 17, 2023

So I checked and it seems the only way to get the Moog UCA bushing that presses into the axle housing is of you get both bushings for each control arm which is a waste of money if you are buying new UCA's. I would just get the bushings and the tool to take them out and install them from Maximum Motorsports.

Control Arm Bushings

Here is a video showing how most of us removed them in the past and how easy the MM tool makes it:

Problem is when you have to install the new ones its a mofo without MM's tool. I had the rear end out of the car and was able to use the ball joint press you borrow from the parts store but it sucked.

Mustang5L5 · Feb 17, 2023

I concur, the MM tool definitely helps.

Rear Upper Control Arm Bushing Tool

I have seen them removed with an air chivel, and installed with a balljoint tool.

Here's another source for the Ford bushings.

FMS-M-4050-B

https://www.summitracing.com/parts/fms-m-4050-b?seid=srese2&utm_source=bing&utm_medium=cpc&utm_campaign=Brands+|+F&utm_term=4582008552116329&utm_content=GSAPI+5ba28318f13b4

Always found it strange that this kit was packaged with C-clips and friction modifier. Seems very unrelated.

AnthonyA1234 · Feb 17, 2023

Yea I’ll pick up that MM took it looks like it’ll save me a lot of headaches lol.

I see some people who unbolt the rear shocks and drop the rear end and I see others who just unbolt the control arms and swivel them out while they have a jack under the arms to keep the spring from flying out. Which method do you guys recommend ?

edit: in regards to the lower control arm change

Mustang5L5 · Feb 17, 2023

Unbolt the shocks and quads (if present) with a jack under the pumpkin. Then, lower the axle down as far as you can without tearing the center brake line. At that point, you can push down on each side of the axle and remove the springs by hand. Then jack up the rear and reconnect the shocks, or place the rear on jackstands while you remove the control arms one at a time.

AnthonyA1234 · Feb 17, 2023

Mustang5L5 said:
Unbolt the shocks and quads (if present) with a jack under the pumpkin. Then, lower the axle down as far as you can without tearing the center brake line. At that point, you can push down on each side of the axle and remove the springs by hand. Then jack up the rear and reconnect the shocks, or place the rear on jackstands while you remove the control arms one at a time.

And when I tighten everything I should jack up the rear as much as it will go to put load on all the bushings correct?

I would just torque everything on the ground but I doubt I’ll be able to reach the upper bolts.

Kid wita 5oh · Feb 17, 2023

You can get the bushings through LMR(with c clips and friction modifier) or rock auto for like $15(various brands)

https://lmr.com/item/M4050B/Mustang-88-Rear-Axle-Installation-Kit

Mustang5L5 · Feb 17, 2023

AnthonyA1234 said:
And when I tighten everything I should jack up the rear as much as it will go to put load on all the bushings correct?

I would just torque everything on the ground but I doubt I’ll be able to reach the upper bolts.

I Jack the rear up and put the axle on jackstands with the weight on the suspension and then torque. The upper ones will be tricky but you can get them.

For the MM arms, if they have the poly bushings with the solid tube inside, you can torque those as you install because even torqued down then move with ease due to the crush tube not being impregnated into the bushing design.

Edit: depends on which arms you get of course.

AeroCoupe · Feb 17, 2023

When I torque the rear control arms I jack the front of the car up as well and load front suspension by putting jack stands under the hats of the front rotors. I try to get the car listing like it does on the ground. Obviously you want to run a couple lug nuts down to secure the rotors to the hubs.

I cannot say if this does much of anything on a street car but we did this on my buddies American Iron car as having the cars CG as close to on the ground was supposed to help. Did it enough it became habit.

I believe you can install the upper bolts such that you can orient the nuts so you can get on them with a torque wrench.

Drivetrain How to fix driveshaft rubbing on the floor pan?

BlakeusMaximus

Still got to try a little lube on my speedo head

General karthief

wonder how much it would cost to ship you a pair

AeroCoupe

lube between the nut and the face. I know my lubes

AnthonyA1234

Attachments

AeroCoupe

lube between the nut and the face. I know my lubes

AnthonyA1234

AeroCoupe

lube between the nut and the face. I know my lubes

AnthonyA1234

AeroCoupe

lube between the nut and the face. I know my lubes

Mustang5L5

That is…until I whipped out my Bissell

AnthonyA1234

90sickfox

Wasn't a pretty sight...and I've got big hands

AeroCoupe

lube between the nut and the face. I know my lubes

Mustang5L5

That is…until I whipped out my Bissell

AnthonyA1234

Mustang5L5

That is…until I whipped out my Bissell

AnthonyA1234

Kid wita 5oh

I'm definitely not in the original hole

Mustang5L5

That is…until I whipped out my Bissell

AeroCoupe

lube between the nut and the face. I know my lubes

Similar threads

Drivetrain How to fix driveshaft rubbing on the floor pan?

Still got to try a little lube on my speedo head

wonder how much it would cost to ship you a pair

lube between the nut and the face. I know my lubes

Attachments

lube between the nut and the face. I know my lubes

lube between the nut and the face. I know my lubes

lube between the nut and the face. I know my lubes

That is…until I whipped out my Bissell

Wasn't a pretty sight...and I've got big hands

lube between the nut and the face. I know my lubes

That is…until I whipped out my Bissell

That is…until I whipped out my Bissell

I'm definitely not in the original hole

That is…until I whipped out my Bissell

lube between the nut and the face. I know my lubes

Similar threads

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