SOT 3 link install on my 69 coupe

[rwcstang 194]

got the week off to tackle this, so far its been a crazy experience. Im looking forward to getting this girl back on the road!

 

[rwcstang 194]

Hey Guys, hoping you can help me out with something, as I'm a little stuck. my lack of knowledge of pinion angles is none existent and im trying to understand it correctly. Before I start, Im running the following: poly motor mounts and stock rubber trans tko mount from MDL. after reading about how pinion angle works on different sites, the summary is they are supposed to be 3" degrees or less and suppose to cancel each other out under acceleration, however, I think I may get my pinion angle wrong.

 

with the MDL TKO conversion kit w/ their Trans Mount, before adjustment, we measured the trans angle at - 4.5 Degrees down, however, I didn't check the angle of the pinion with the stock axle/leafs, ugh I wish had.

 

we shimmed the MDL trans mount, and the best we got was +3.5 degrees up and transmission was already hitting the top tunnel/shifter hole, also per SOT instructions, we started the 3rd link at 3 degrees up as a baseline and I lowered it 2 degrees down to 1 degree, this was to compensate from the pinion moving up when accelerating, assuming I did this wrong, would someone educate me? should I have done - 3.5 down instead?

 

OR

 

should I have left the TKO Trans mount as is (4.5 degrees down and raised the 3rd pinion angle slightly higher to match the transmission angle, when under acceleration they would cancel each other out or do I have it wrong?

 

still got a lot to learn here, so excuse the ignorance and overthinking.

 

https://www.motortrend.com/how-to/pinion-angle-change?slide=2

[Casgar 21]

I'm pretty much a novice too, but from what I understand it's the relative angles between the transmission and the pinion, and their centerlines that is of interest.  The angles relative to the car/ground is more a concequence of trying to keep the driveshaft angles correct.

Also, I think the 3-link would raise the pinion less under acceleration compared to leaf springs.

[det0326 171]

Ideal would be 1 degree down on transmission tail shaft and 1 degree up on pinion yoke. Since 3.5 down is all u can get on the TKO without tunnel modification then u need the yoke up 3.5 degrees. On stock leaf springs u would want pinion up 2.5 allowing 1 degree wrap up on take off but on the 3 link probably not necessary.

[RPM 1,143]

On my triangulated 4 bar rear I put the trans and pinion at the same angles. No issues after 6 years. 

[rwcstang 194]

On 2/20/2023 at 9:05 AM, RPM said:

On my triangulated 4 bar rear I put the trans and pinion at the same angles. No issues after 6 years. 

Thanks, I spoke with Shaun and he recommended the same thing, I mentioned to him that my 3rd member sits slightly higher than the shimmed transmission mount, he still said to put the angles the same, so trans down, adjust the 3link pinion up, so Im going to take a few shims away and let it sit at 4 degrees down and raise the pinion angle to 3.5-4 and see if the clunking while shifting/acceleration improves, it will most likely look like image 3 but reversed. 

[rwcstang 194]

On 2/20/2023 at 8:53 AM, det0326 said:

Ideal would be 1 degree down on transmission tail shaft and 1 degree up on pinion yoke. Since 3.5 up is all u can get on the TKO without tunnel modification then u need the yoke up 3.5 degrees. On stock leaf springs u would want pinion up 2.5 allowing 1 degree wrap up on take off but on the 3 link probably not necessary.

yeah, Im going to drop it some to 4 degrees and adjust the 3link to match the trans, originally with the MDL mount it sat at 4.5, at 3.5 degrees the TKO is rubbing against the trans tunnel and making a squeaking/metal rubbing sound and driving me nuts as it comes and goes

I do have a TKX to install but later on, and since the TKX and TKO600 are the same and one is smaller, I can probably go back down to 3.5-3 degrees with out touching the tunnel, they use the same mounting hardware. but going to try to adjust with the TKO as I need to keep testing this suspension and brake in the new 3rd member. 

excuse the drawing but assuming its going to look like this after I adjust it, the other option is to raise the car and adjust the coilovers and have the 3rd link/pinion get closer in balance with the transmission. 

does that make sense? 

[det0326 171]

2 hours ago, rwcstang said:

yeah, Im going to drop it some to 4 degrees and adjust the 3link to match the trans, originally with the MDL mount it sat at 4.5, at 3.5 degrees the TKO is rubbing against the trans tunnel and making a squeaking/metal rubbing sound and driving me nuts as it comes and goes

I do have a TKX to install but later on, and since the TKX and TKO600 are the same and one is smaller, I can probably go back down to 3.5-3 degrees with out touching the tunnel, they use the same mounting hardware. but going to try to adjust with the TKO as I need to keep testing this suspension and brake in the new 3rd member. 

excuse the drawing but assuming its going to look like this after I adjust it, the other option is to raise the car and adjust the coilovers and have the 3rd link/pinion get closer in balance with the transmission. 

does that make sense? 

That should work fine. 

[rwcstang 194]

Alright update 2: Original thread: https://www.vintage-mustang.com/threads/sot-3-link-watts-install.1209996/

After checking pinion angles, I finally was able to get the right angles I needed. Thanks to you all and Shaun from SOT. 

I took the car for a drive but car kept bottoming out and had a loud thump (pinion yoke hit the 3rd link heim joint) after readjusting the coilovers (more height) and resetting pinion angles car was much better and wasn't bottoming out. Finally, I took the car to an alignment speed shop here in mountain view to redo the front alignment and check the rear suspension if there was any issues. 

tech said everything was good with front alignment so no major big change, other than my idler arm was failing (was on my list to do anyways), so we swapped it to open trackers roller idler arm.

as for the rear suspension, shock compression was good, but rebound of the shock was a concern, he showed me by lifting the car on the lift it would not fully extend would move have 1/4 an inch, but suggested if I want full rebound (better ride quality) possibly a 1/2 - 1" coil over spacer may work but overall due to the limitation shock mount, its leaves little to no major re-adjustment like the TCP Quadra link or other kits out there, only real adjustment you have is to adjust the coil over spring. 

now, during the break-in process of the strange rearend, I have been getting this gear whine since first install, noted I understand some kits like mine will make noise as the 3rd link or 4 links brackets are welded on to the rearend housing which causes the noise. however, I spoke with others that have this kit and seen their videos, none provide this gear whine. let me know what you think. 

https://drive.google.com/file/d/10eIgOuF0ek8i8K0XVhzRjR6q1tqahJiZ/view 

emailed SOT, said that is normal i need to add sound deadener to limit the vibration sounds, however in the main cabin has some sound deadener but not the trunk. I still think it's the gears making this noise. 

per strange engineering break in procedure I need to use non synthetic 85w-140, I used Motion Pro (Oreilly brand) first, then after 200 miles, I decided to change fluids I did see metal shavings, assuming this is normal during breakin. 

I changed fluids again but I used lucas 85w-140, however, no real change and the whine is loud above 40mph

SOT hasn't responded, Im sure he's probably busy so ill wait and email again. but if no action is taken, Im going to remove the rear and send it back to strange for inspection. 

Ugh, just when you think you can enjoy the car you go back to square 1. 

 

 

 

 

[RPM 1,143]

I couldn't get the video to play. I've never had new gears, but I don't think shavings are normal. Are they shavings or powder like?For the price of what stuff costs today, I wouldn't put up with a loud whine. I had a set of used 3.70 gears that were very loud, and no amount of adjustment could quiet them. 

That rear rebound situation sounds goofy. What did Shaun say about it? Can you post pics of your car ride height and rear coil overs?

 

[rwcstang 194]

11 hours ago, RPM said:

I couldn't get the video to play. I've never had new gears, but I don't think shavings are normal. Are they shavings or powder like?For the price of what stuff costs today, I wouldn't put up with a loud whine. I had a set of used 3.70 gears that were very loud, and no amount of adjustment could quiet them. 

That rear rebound situation sounds goofy. What did Shaun say about it? Can you post pics of your car ride height and rear coil overs?

 

try using firefox or different browser, for some reason on chrome it requires to sign-in or it won't show. its on my gdrive and that link is for public view (go figure) lol. 

The fluid was more powder like, like a metallic flake paint, I hovered a magnet over the stream would move slightly. 

in regards to the rebound shock part, I let shaun know and he responded back: I haven't had a need to modify the shocks.  There won't be an enormous amount of droop travel, it isn't really required unless you are picking up inside rear wheel in turns (won't happen) or are off roading it (not going to happen hopefully). 

again, I'm not going modify anything with out his Shaun's guidance/approval, but it was just a concern from the shop Tech as I wanted transparency on the install.  

As for the rear end gear whine Shaun followed up with me yesterday and spoke with his Strange Engineering rep: 

PRF130 WITH TRUTRAC

DID HE DO THE BREAK IN PROCEDURE ?

SEE THE NOTES  IN THE PDF ATTACHED

THEY ARE TIGHT AND WILL MAKE NOISE

FOLLOW THE BREAK IN PROCEDURE

USE 85-140 NON SYNTHETIC OIL  

IF STILL ISSUES  HE WILL  HAVE TO SEND IT IN FOR INSPECTION

PLEASE ADVISE

I've already responded back with answers and follow up questions: 

• 200 miles in breakin procedure, but stopped due to the gear whine and didn't want to void warranty. 
• First used Master Pro 85w-140 conventional gear oil
• changed fluids to Lucas 85w-140 Conventional gear oil
• What Brand Gear am I using? Some Brands tend to have gear whine (Im running on 3:50's)
• In regards to a "tight fit" (which will make noise), is there a way to know what the tolerances are for this type of setup? i.e backlash set up..etc.

Ill take pics of the stance on where it sits now haven't had the time due to work. 

 

 

[rwcstang 194]

On 4/25/2023 at 10:18 PM, RPM said:

 Can you post pics of your car ride height and rear coil overs?

 

took some time today.

first right height, roughly under 25" new height is above 25"