bjkadron
Well-Known Member
Just curious, if you didn't know you had the clutches, were you running a friction modifier in the oil? If not that may have hastened it's demise. Also are you upgrading it or just replacing with stock clutch style?
12:05 Garage- ’70 Duster build
- Thread starter racerjoe
- Start date
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Just curious, if you didn't know you had the clutches, were you running a friction modifier in the oil? If not that may have hastened it's demise. Also are you upgrading it or just replacing with stock clutch style?
racerjoe
Well-Known Member
I've always run oil with friction modifier. I'll just rebuild this one. Looks like Dr. Diff has the parts.
Does anyone know if the clutches actually have some type of organic clutch material on them? The ones that came out are all steel with no remnants of clutch material.
bjkadron
Well-Known Member
So weirdly enough the pictures I'm seeing online don't look like there is any friction material. Does it just use the metal plates? Strange but technically possible. Not sure what that means for your root cause analysis. I'd maybe call Cass and ask. I've never had one of these apart.
racerjoe
Well-Known Member
I sent him an email. He says they are steel without any type of organic clutch material and should be generously coated with straight friction modifier during assembly. Mine do look pretty beat up. I ordered all the new parts from him today. As far as the failure analysis, maybe it's just 50 year old junk deciding to give up on life. His website says something about his parts being "heavy duty". Perhaps the original style had a weak point.
bjkadron
Well-Known Member
That's really interesting that it is all metal as the friction material. I guess that is why it lasted as long as it did.
And also, if I'd been beaten on for 50 years I'd probably get a little tired too
. Especially if this is the same rear you used for drag racing... that is quite a few shock loads.
racerjoe
Well-Known Member
This one had a fair amount of drag passes on it until I started making enough power that it would make the car drift left on the launch. I built another rear with a spool after that. Lets not forget the 150+ autocross runs in the last few years also.That's really interesting that it is all metal as the friction material. I guess that is why it lasted as long as it did.
And also, if I'd been beaten on for 50 years I'd probably get a little tired too
racerjoe
Well-Known Member
A little late on updating on the diff repair. The new parts from Dr. Diff are a much better design. The old one essentially had two sets up splines stacked. This is what ultimately twisted my Dr. Diff axles. There will be two different forces being applied to these splines.
The new design puts all the axle splines on the gear and split between the gear and "pressure plate" for the clutches. Much better design in my opinion. I had back together the weekend after the failure. Everything seems to be in working order now.
I also got a set of Manley pushrods. They are .080" wall compared to the .060" wall stockers. The difference can be felt in the weight alone. Time to turn that rev limiter up!
The new design puts all the axle splines on the gear and split between the gear and "pressure plate" for the clutches. Much better design in my opinion. I had back together the weekend after the failure. Everything seems to be in working order now.
I also got a set of Manley pushrods. They are .080" wall compared to the .060" wall stockers. The difference can be felt in the weight alone. Time to turn that rev limiter up!
That was pretty neat to listen to... I need to get with them for one of those steering boxes eventually...
DionR
Well-Known Member
Can't wait to see what you have planned. Looking at your previous work, I doubt it will be a total waste of time.
bjkadron
Well-Known Member
Woot! Can't wait to see what you come up with!
I do R&D for a living. There have been many times I thought "This Is It!!" only to learn new lessons (results weren't what I had hoped for). But, there have been many times when my calculations came in spot on. Of course there was the once (or twice) where the experiments exceeded my expectations. You are a "tinkerer", learning as you go. What I appreciate is that you are saving numerous others from the failures by sharing your results -- positive and negative. Thank you!
racerjoe
Well-Known Member
There’s some engineering behind this, but not nearly as much as I had hoped for. Contacted a couple dudes with corner scales and they wanted to help until I tried to actually schedule a day. The good news is it will have some adjustability to save me from “mis-guessing”
bjkadron
Well-Known Member
Look on the bright side, you know you definitely need more front roll rate. Worst case you overshoot it and it's not right. You still aren't any worse off then now because it still isn't right.
racerjoe
Well-Known Member
Where were you with this information a month ago Dan?
Didn't think about it until saw that your contacts and their scales, ghosted ya
racerjoe
Well-Known Member
Several parts arrived for my sway bar, but still waiting on a major piece before I can start figuring out the arms.
This is the basic hardware. The flat plates are saddles for the outer tube that the bar will go in. This will bolt where the normal sway bar bushing brackets mount. These are "half splined shafts" I found online. I believe they are some type of farm equipment parts, PTO for a tractor maybe? These are 1.25" diameter with matching splined couplings.
The actual sway bar is 1.5" OD 4130 DOM tubing, .188 wall. This makes the ID 1.124". Obviously the shaft needed to be turned down to insert into the tube.
This is the saddles after I bent them.
The outer tube will be 2" diameter with a 1.76" ID. The bronze bushings will go in the ends of that, which have a 1.5" ID to match the 1.5" OD tube. The aluminum shaft collars will hold the bar in place. The 2" tube should arrive this week. Once I get that, I can mock everything up and design some arms, which will weld to the splined couplings.
So you may be wondering how I came up with this size tube. Good question. As everyone knows, I ran the torsion bar setup with many Hotchkis parts. Their bar is 1.5" x .188 tubing. I used the online Adco sway bar rate tool to determine the rate of their bar. My wheel rate should be very close to what it used to be, so I'm making this bar fairly close to that rate. I'll make my arms with a few holes to adjust it. Worse case, I make another bar with 1.5" X .145 tubing to decrease the rate.
This is the basic hardware. The flat plates are saddles for the outer tube that the bar will go in. This will bolt where the normal sway bar bushing brackets mount. These are "half splined shafts" I found online. I believe they are some type of farm equipment parts, PTO for a tractor maybe? These are 1.25" diameter with matching splined couplings.
The actual sway bar is 1.5" OD 4130 DOM tubing, .188 wall. This makes the ID 1.124". Obviously the shaft needed to be turned down to insert into the tube.
This is the saddles after I bent them.
The outer tube will be 2" diameter with a 1.76" ID. The bronze bushings will go in the ends of that, which have a 1.5" ID to match the 1.5" OD tube. The aluminum shaft collars will hold the bar in place. The 2" tube should arrive this week. Once I get that, I can mock everything up and design some arms, which will weld to the splined couplings.
So you may be wondering how I came up with this size tube. Good question. As everyone knows, I ran the torsion bar setup with many Hotchkis parts. Their bar is 1.5" x .188 tubing. I used the online Adco sway bar rate tool to determine the rate of their bar. My wheel rate should be very close to what it used to be, so I'm making this bar fairly close to that rate. I'll make my arms with a few holes to adjust it. Worse case, I make another bar with 1.5" X .145 tubing to decrease the rate.
bjkadron
Well-Known Member
I really like this solution, I think it should get you in the ballpark at least for roll stiffness.
racerjoe
Well-Known Member
I welded and painted some stuff....
I also welded the spline shafts to the 1.5" tube and put it all together. The fit is super neat and the shaft spins freely inside on the bronze bushings. They are supposed to be self lubricating, but I put some oil on them anyway. I also greased between the aluminum and bronze just to cut down on the friction.
I also welded the spline shafts to the 1.5" tube and put it all together. The fit is super neat and the shaft spins freely inside on the bronze bushings. They are supposed to be self lubricating, but I put some oil on them anyway. I also greased between the aluminum and bronze just to cut down on the friction.
DionR
Well-Known Member
Aren't there pre-built splined swaybars you can buy? Not something I have looked into, just a preconceived notion of mine.
racerjoe
Well-Known Member
Yes, sprint car and nascar use them. I'm sure others. Plenty out there, but none that would work for me. Either too long or too short. They also don't publish the spring rates. There's a company in canada that makes splined ends specifically for sway bars, but only in one size. They also make a split coupling for the splines. Before I came up with this idea, I was going to make that work, but it was pricey. Detroit speed makes this design for GM products. They are over $1K.
DionR
Well-Known Member
Gotcha. I assumed they had multiple lengths but didn't look anything up.
Thanks for the explanation.
bjkadron
Well-Known Member
Yeah there is a few companies that make them but none are cheap. If you buy everything you are looking at close to $1k by the time you are done. Also as he said, A-bodies are kinda an odd size/length depending on your setup. Plus having a large hollow tube like this you can get a higher rate with a lot less weight then a solid or even gun drilled normal bar.
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