47-55.1 Tie rod questions 2

[51 3600]

Started a thread "Tie rod questions" a month ago and received a lot of good help from folks on here and an education as well. Realizing I had multiple problems I decided to make a list and tackle problems one at a time.

First, using threaded rod, set the desired ride height as best I could given not having full weight on front end. Almost assured I will have to cut or replace the stock springs, so I'll wait til truck is sitting with full weight to do that.

Second, notched the frame to correctly mount the stock upper control arms on inboard side of the mounting plate.

Third, decided to dump my Camaro rack and will order a rack for a '88 Tbird which will get rack and control arm pivot points more inline.

Forth, where I need help again, arrgh. I'm trying to find an outer tie rod end that will fit both the Tbird rack and my Blazer steering knuckle. Are F**d and Chevy tie rod tapers the same? In my research I find conflicting info but keep coming across an angle of 7.15* or 1.5"/ft. TRE specs, when I can find them, show small and large taper dimensions of stud diameter. They don't give taper length so you can't compute the angle.

Using RockAuto.com to find TREs:
I can find a Moog ES2150R for the Tbird rack with a taper of .556-.626.
For a Blazer knuckle a Moog ES3379t with taper .452-.577 or a Moog ES33802t with a .516-.592 taper. If F**d and Chevy tapers are the same then taper diameter just determines how far the TRE fits into the knuckle. Is that right? I understand the thickness of the knuckle has implications too.

Fifth, I have to refab mounts for Tbird rack.

Sixth, who knows?

[dsraven]

you could try the email section for Dorman products, they make a lot of OEM stuff. maybe they could let you know a degree angle instead of a dimensional spec. moog also has an ask a question section. a lot of tie rods have a 7 deg taper, lots of 7 deg tapered reamers out there as well. if asking the question section also ask what type of interference angle might be used, as in, if the toe rod taper is a little different than the angle of the taper in the spindle. like the tie rod would possibly 7.15 deg but the spindle is reamed to 7 deg for an interference fit?
for rack mounts try welders series, page 2 of handy parts. Canadian company so USD goes further. they shouldn't be too hard to fab but if available and not too many days to wait, why not get some pre-made ones.
ok, below is just what I THINK an IFS should look like. don't take it as gospel but think about the consequences of getting it wrong and having to do it over. there are lots of sites that talk about steering geometry, bump steer, scrub radius, anti dive angles etc.
when installing the rack, I believe, it should be inline with the tie rod holes in the spindles, so if you strung a line from one side to the other the rack would be centred on that, with wheels straight ahead, at ride height. that gives the least chance of changing the steering toe in etc with a change in vehicle height or a difference from one side to the other as the vehicle leans around a corner. the pivot points for the inner tie rods should line up with an imaginary line drawn through the upper and lower control arm pivots with wheels straight ahead. again, to lessen changes in steering as the vehicle suspension moves. maybe check all that geometry stuff out before you install the rack mounts so you have a great steering truck and also one you feel safe in.
the steering column u joint scenario works best with an equal number of u joints because a ujoint speeds up and slows down the shaft as it goes through one rev at an angle. more angle means more speed fluctuations. if they run in pairs at the same angles then one joint cancels the other joint. if uneven number of joints are used or the angles are mismatched too much then the steering can get weird because the shaft actually speeds up and slows down a couple times in one rev.
anyway, hope that helps and doesn't confuse

https://welderseries.ecwid.com/Handy...2955?offset=30

Technical Support Available
Phone: 1-866-933-2911
Email: techsupport@dormanproducts.com

https://www.moog-suspension-parts.com/moog-es2150rl

u joint phasing video
https://www.youtube.com/watch?v=Idk3BVDVHq4

[51 3600]

Thanks for the response and info dsraven. Thanks too for the reminder of Welder Series. They’re a good source and I’d forgotten about them. I’ll try contacting Dorman and Moog online or email. Call to Moog tech didn’t get me anywhere. Maybe if I give them part numbers for Tbird and Blazer TREs they can give me taper angles rather than dimensions.

I already had my steering set up for the Camaro rack. I expect I will have to modify that for the Tbird but I hope only slightly. Shaft has 3 u-joints so not in phase but they are in sync. I kept the angles as small as I could and all are well within acceptable parameters.