Watts link buildup

[RallyBob]

Hello all. Thought I'd post a few pics of my latest fabrication. I recently got a 4-door Ascona for use as a beater car, and decided that I would fit a watt's linkage to the rear axle in lieu of the typical panhard bar.

The plus side of a watt's link is that it allows for near perfect vertical travel of the rear axle compared to a panhard bar. In fact by comparison, my watt's link allows for 12" of vertical travel (the shocks only go 9" so that's a moot point) with zero deviation from left to right. The stock panhard bar allows for about 3/16" of side-to-side deviation in 9". The down side to the watt's link is far greater complexity and price. So, in typical fashion for me, I decided to build my own instead of buying a 450-euro pre-built version from Germany.

In the end I have about 7 hours into mine, and material costs are about $170 total.

[RallyBob]

And the last two pics:

[IT Manta]

Excellent work as usual Bob!

[namba209]

Doggone it Bob, there oughta be a law against such superb craftmanship. A minor suggestion, if I may, from my USAF flight control system push-pull rod sustems. How about a .040" safety wire hole in the jam-nut, with a .040" hole in the purple rod end for some .032" nichrome safety wire. Just a suggestion.

[wrench459]

Another piece of art work. I'm always amazed with your craftsmanship.
Thanks Bob for the pictures..cant wait to see the frame mounts.

[Phoenix]

Always amazing.

[newman27]

I had no idea what a Watt's Linkage was - I learn a lot on this site!

Matt

[RallyBob]

Thanks for the kind words guys. I should have mentioned that anyone wanting to see more pics can go to my flickr site as I have a few more details in there.

Ron, I decided to use nylon-insert nuts on the fasteners, and the large center pivot bolt will also have some loctite added. I'm not going to safety wire this setup as it's 'only' a street car!

If anyone else decides to try this themselves I could make a detailed list of parts I used...metal thickness', bearing part numbers, etc. For your average street car the center pivot need not be as long as mine is, as you'll probably never approach this much suspension travel in situ.

Bob

[RallyBob]

Oops, almost forgot to mention. I drilled a few extra holes into the differential cover and the diff housing itself, and fitted a few dowels to help spread the lateral loads on the differential cover. Probably not necessary as I've never seen anyone else do it, but it was cheap and simple to do.

[yellaopelgt]

Awsome!!!!! I was wondering if there is any worry of warping the diff cover with so much welding?? Or for that matter, are you using HEAVY DUTY bolts to mount this back on? My thoughts are that this could possibly cause a leak in the diff with so much stress being there.....although,now thinking about it, I suppose it IS a central location(pivot point)....so most of the "stress" would be where it attaches to the car??? As always Bob, you da man!!
Joe

[RallyBob]

Originally Posted by yellaopelgt Awsome!!!!! I was wondering if there is any worry of warping the diff cover with so much welding??

Since I TIG welded it, and did it in small sections, there was zero warpage. I can place the cover on my welding bench (3/8" steel) or on the diff housing itself and there is zero 'rocking'. The stock housing cover is very beefy, and in fact you can drive an Opel over it and it won't bend. (I've used them as wheel chocks before!)

Or for that matter, are you using HEAVY DUTY bolts to mount this back on?

The stock bolts are actually quiet overkill! Grade 10.9 with a large flange and serrations under the head of the bolt. I'll probably loctite them to be sure, and I already decided to forgo using a diff gasket, and instead will use some 'Right Stuff' gasket maker. Less chance of the cover shifting under lateral loads. And don't forget I added a few dowels to help out.

Bob

[2 Fast 4 U]

Originally Posted by RallyBob If anyone else decides to try this themselves I could make a detailed list of parts I used...metal thickness', bearing part numbers, etc...... Bob

Nice work Bob, could you make a detailed list of parts that you used??
Are you going to make photos how the linkage is mounted to the chassis??

[RallyBob]

Originally Posted by 2 Fast 4 U Nice work Bob, could you make a detailed list of parts that you used??

Yes of course, but it probably won't do you much good as you're in the Netherlands! I think that you would have to purchase items that are locally available. Everything I bought is SAE (not metric), and I don't know if they would ship anything overseas anyway. I got everything either from McMaster-Carr or from Speedway Motors.

Are you going to make photos how the linkage is mounted to the chassis??

When I get the car on my lift, yes. But that is quite far away. I have numerous other cars to finish first. Maybe spring time?

Bob

[OriginalOpelGTOwner]

Excellent craftsmanship!

Ford Motor Company added a Watts Link to the rear suspension of the 1997 Model Year Town Car, Crown Victoria and Grand Marquis to improve tracking and I beleive it is still in production at the Saint Thomas Assembly Plant in Ontario, Canada. The differencial cast iron housing was modified to incorporate the mount for the pivot bolt. During durability testing it was discovered that the cast iron housing had to be modified further to withstand the high laterial loads during rough road handling tests without fracturing.

The laterial load pins and cover reinforcements are certainly required.

[RallyBob]

Alrighty, here's my list of parts I used. I had a few of the items already which I didn't have to buy, and the metal itself was free (nice to be next door to a metal shop!). I also bought a couple items at a local hardware store (bolts).

Speedway Motors stuff:

*1170810 - RH male alum. rod end, 5/8" shank w/ 1/2" hole, 2 req'd @ $9.99 ea
*1170810L - LH version of above rod end, 2 req'd @ $9.99 ea
*1756046LH - LH jam nuts, pack of six, $3.99
*1756046RH - RH jam nuts, pack of six, $3.99
*91034158-14 - 7/8" OD alloy tube, with LH/RH internal 5/8" threads and 14" long overall, 2 req'd @ $7.99 ea (note this fits a Manta/Ascona A, not GT)

I could have made the links with chromoly rod ends and steel wedged tubing for a little more money. A GT would need shorter links as well, but I have not measured for them.

McMaster-Carr stuff:

*91247A483 - 3/4"-16 x 4" long grade 5 bolt, five-pack, $10.96
*91342A240 - 3/4"-16 nylon insert thin locknut (.406" tall), 10 pack, $6.93
*5909K33 - 3/4" caged needle roller thrust bearing, 2 req'd @ $2.60 ea
*5909K59 - 3/4" hardened thrust washer, .126" thick, 4 req'd @ $2.20 ea
*7815K48 - 3/4" ID flanged high strength (alloy 932) bronze bushings, 2 req'd at $5.60 ea

Misc.

*3/8"-24 x 3" long grade 8 bolts for back brace - 2 req'd (hardware store)
*Also 2 each grade 8 flat washers and nuts, also 3/8"
*Short pieces (mine are 2.275" long) of 1/2" OD x 3/8" ID stainless tubing for supporting the back brace.
*1/2"-20 x 1.25" grade 8 bolts and nuts (2 ea) to attach lateral links to the center pivot.
*Short piece of 1.25" OD x 1" ID steel tube for center pivot sleeve, I think it was 1.25" long?
*I used 12 gauge steel for the vertical pivot main body, and for the reinforcements welded to the diff cover. The remainder of material was 14 gauge steel.

My vertical link uses 5.25" center-to-center holes for the transverse links. I think you can use about 4.5"-4.75" and get 8" to 9" of travel from the rear axle before it starts to deviate left-to-right. This would make the entire setup more compact. The center link I made is 2.25" wide at its' widest point, and the ends have a 1.25" radius.

The back brace strap is made from 14 gauge steel, it's 5" center to center at the mounting holes, 1.625" wide at the center, and 1" radius at the ends. The return flange I bent (for strength) is 3/16" wide.

IIRC, the 'box' I welded to the diff cover is 4.5" x 3.25" across its' face.

Another note: I could have easily simplified this by deleting the needle roller bearings. They do make the pivot far smoother, but I've never seen anyone else bother to do this. Removing them makes the entire pivot a lot shorter, by about 3/4". I cut the large 4" x 3/4" pivot bolt down after I made the watt's link, it barely protrudes past the head of the short nylon locknut now. Note: after everything in the pivot is greased well, the pivot lock nut is tightened only until there's zero slop so the bearings will pivot smoothly...do not torque it down! I will also use loctite on the locknut to keep it from loosening, although it's probably redundant.

At this point I have not made the attachments to the chassis itself, but the material costs will be minimal. Basically I will extend the factory panhard chassis mount downward as needed, and add another similar mount to the other side of the car. Add two more mounting bolts to the transverse links and there you have it!

HTH,
Bob

[heimue]

Bob, every time I see something built by you I envy you for your TIG welder! That's about the only tool that I don't have, but certainly want!

Dieter

[wrench459]

Originally Posted by RallyBob At this point I have not made the attachments to the chassis itself, but the material costs will be minimal. Basically I will extend the factory panhard chassis mount downward as needed, and add another similar mount to the other side of the car. Add two more mounting bolts to the transverse links and there you have it! Bob

With all that travel wont you need to shorten the pass side mount and lengthen the drivers side?
BTW what's your labor rate for custom work? Seven hrs. bill time X shop=
a terrible Opel habit.

[RallyBob]

Originally Posted by wrench459 With all that travel wont you need to shorten the pass side mount and lengthen the drivers side?

Basically a watts linkage needs to have the lateral links parallel to the ground at static ride height, in order to have optimal travel in compression and droop. So the driver's side chassis mount will be low...a bit below the bottom of the diff housing. The passenger (right) side chassis mount will have to be quite a bit shorter, almost in line with the top of the axle tube. This works out well since I will have more room for exhaust on the left side which is where an Ascona exhaust crosses the axle.

BTW what's your labor rate for custom work? Seven hrs. bill time X shop= a terrible Opel habit.

Well if I ever start a shop I'll have to figure that out! I work dirt cheap for a few close friends, otherwise I turn a lot more work away than I take on.

[Aardvaark]

What! You didn't machine a new billet diff cover???? Ha!
Nice design and fab, as usual.

[Hiro]

Superb work as usual Bob!
It's a pity it hides under the car!
Hiro

[Wolfman3002]

Originally Posted by Aardvaark What! You didn't machine a new billet diff cover???? Ha!

Hey, that's not a bad idea, maybe w/ the Opel blitz across it? Wonder what it would cost?

[RallyBob]

Originally Posted by Aardvaark What! You didn't machine a new billet diff cover???? Ha! Nice design and fab, as usual.

It *would* be pretty neat, however:

A) I'm not a machinist
B) I'm not a machine programmer
B) I have no milling machines
C) I think the cost of the billet I would need to begin the project is about double my total investment so far!

Any time I can fabricate and weld I go that route. Far cheaper for me, and well within my abilities. Someday I'd love to learn to machine stuff but I can't justify the cost of the machinery for my own personal use...yet.

[RallyBob]

Originally Posted by heimue Bob, every time I see something built by you I envy you for your TIG welder! That's about the only tool that I don't have, but certainly want! Dieter

Dieter, I must admit my TIG welder is one of my favorite tools. It's a close race between my car lift, my TIG welder, and my Woodward Fab hand shear (I use it every day!).

The trick is to TIG every time you get a chance. Practice!

[2 Fast 4 U]

Originally Posted by RallyBob Originally Posted by 2 Fast 4 U Nice work Bob, could you make a detailed list of parts that you used?? Yes of course, but it probably won't do you much good as you're in the Netherlands! I think that you would have to purchase items that are locally available. Everything I bought is SAE (not metric)....... Bob

Thank you, I just needed the items and size you used, I can convert to the metric sizes that are available here in Europe

[opeletti75]

i want one no i want three