Front suspension geometry questions in regards to a SAS. (10 Viewers)

[Dindu Nuffin]

Hey, sorry if this is in the wrong spot, but I can't find a better place for it.

I'm looking at doing a SAS on my '06 Sequoia and would really like to keep it as Toyota as possible. I'm considering going with an 80 front end to include the control arms, housing, panhard, springs and shocks. Yep, the big tree's got a drivers drop and I'm aware of and willing to take on the work needed to flip the axle. I know the current going price for a drivers drop D44 is about a case of beer, but again- I'd like to keep it as Toyota as possible. I used to have a few 80's and am very familiar with how the front end behaves and would like to replicate that with my Sequoia. I do hear a voice in the background telling me that it'd be a good time to do a three link, but that seems more complicated than welding in two control arm hangers, more math, and provides way more flex than I need; the flex of the OEM 80 front end is more than enough for me. Hell, the IFS flex is, eh... doable... but the extra travel from a SAS would reduce/eliminate head toss and most importantly- no more LBJ time bomb.

That all said, this is my first foray into a SAS. I'm not new to fabrication, but I want to make sure all the bases I'm not sure about are covered before I move forward with the project.

If I were to get the caster and pinion angles spot on and use the wheelbase measurement to determine where to add the control arm mounts, is it reasonable to expect the 80 front end to behave the same under my Sequoia as it did under my 80s? I'm currently at a 4" lift and don't want to go any higher and since I'd be stripping the axle bare, I can reweld the arm mounts and knuckle balls where they'd need to be to get the pinion and caster angles correct.

Other bridges I know I'll need to cross will be WMS measurements (I really do want it to match the IFS width to retain the tidy look of OEM wheels inside OEM fenders and it is vital to me to keep the scrub radius as close to factory spec as possible), and all the other small stuff like drive shaft, steering box, ect... I'll address those as the planning phase progresses and before I start buying parts.

Thanks for reading my book, and I'm looking forward to reading some to the point responses that either confirm my thoughts or steer me away from it.

 

[tmxmotorsports]

I'm sure it can be done if you can fabricate and know how to set all the angles. Just gotta get after it.

 

[Broski]

To do the axle flip you would need to cut the knuckles lose and rotate them and then you still end up with a 8” diff.
For the amount of work & cost you might as well just get a custom housing, 9.5” diff and 80 outers.
I would spend some time in the hard core corner were guys are doing a lot of the stuff your thinking about doing.
I know you want to keep it all Toyota but in reality a ford super 60 would be the most cost effective axle and is way stronger.

 

[mudgudgeon]

Its not only rotating the knuckles, also need to alter the flange the diff centre bolts into, cut new clearance notches for ring gear, and drill and tap new stud holes so the high pinion centre is up the right way.
And cut out and flip the front cover of the pumpkin so the bump out works for the flipped centre
And cut off radius arm mounts and flip them too
And spring and shock mounts
And panhard rod brackets
And any other brackets for brake lines etc

If you have lots of time on your hands, and low budget, and fabrication skills it can and has been done.

Check out the last few pages of @SNLC "pigpen" thread. He's basically doing all the stuff you'd need to do now, but starting with a bare custom housing

 

[slow95z]

would be better to just get a 3FE semi float rear and work with it. cut the ends off and put the knuckle balls on it. you can then flip the chunk around facing the other way and get a driver's side drop that way.

its the only way i can think of keeping it all toyota dn not doing a custom housing (which is obviously the best way) but i still think the whole thing is dumb. just get a D60 and go coil overs. why get a 8 inch and radius arms after all that work?

 

[Broski]

would be better to just get a 3FE semi float rear and work with it. cut the ends off and put the knuckle balls on it. you can then flip the chunk around facing the other way and get a driver's side drop that way.

its the only way i can think of keeping it all toyota dn not doing a custom housing (which is obviously the best way) but i still think the whole thing is dumb. just get a D60 and go coil overs. why get a 8 inch and radius arms after all that work?

With the semi float you do get the 9.5 diff but I still think the D60 is the way to go.
Just cutting all the brackets off a rear axle is a boat load of work.
Buy the time you get everything you need to make it work your talking D60 money

 

[slow95z]

With the semi float you do get the 9.5 diff but I still think the D60 is the way to go.
Just cutting all the brackets off a rear axle is a boat load of work.
Buy the time you get everything you need to make it work your talking D60 money

Oh I agree but he said he wants to keep it all Toyota which is really hard to pull off without a ton of work and money only for it to turn out inferior

 

[baldilocks]

 

[Broski]

Oh I agree but he said he wants to keep it all Toyota which is really hard to pull off without a ton of work and money only for it to turn out inferior

I get the a hole Toyota DNA thing but the rig in question is made in the US

 

[SNLC]

I am doing what I am doing because it’s fairly cheap. I didn’t pay for the 8” Diamond housing. I have never done it too so it is fun doing something new.

Also, little diff and big tires = lots of ground clearance!

Cheers

 

[Dindu Nuffin]

Yeah, that's all great, but none of that actually answers my question.

 

[baldilocks]

Yeah, that's all great, but none of that actually answers my question.

You haven’t gotten an answer to your question because it’s very likely this is uncharted territory. May I ask why you feel it’s necessary to do the sas on your Sequoia?

 

[cruzinfj1]

If I were to get the caster and pinion angles spot on and use the wheelbase measurement to determine where to add the control arm mounts, is it reasonable to expect the 80 front end to behave the same under my Sequoia as it did under my 80s?

Sure!

Sell the Sequoia and buy an 80.

 

[Broski]

It won’t be the same close but not the same.

 

[Dindu Nuffin]

You haven’t gotten an answer to your question because it’s very likely this is uncharted territory. May I ask why you feel it’s necessary to do the sas on your Sequoia?

Thank you.

Lack of flex from IFS = lots of head toss. Toyota's asinine choice to use upside down ball joints on the LCA. You can add to that all the other negatives people say about IFS, if you want. Truthfully, if this thing had 100 series front suspension, this thread wouldn't exist. The 80 front end as it is out of the box will meet my performance needs with a considerable bit of safety margin and has proven itself in the harshest conditions around the world for the past three decades. In comparison, I check my LBJs after every trip and then wonder, "is next time going to be the one where they break?" This year so far, I've come across a 4R and a Taco with popped LBJs on the trail and a lot more stuff under there gets fragged out than just the ball joint. It also sucks because it basically shuts the trail down for everyone else. I really don't want to be that guy; I'd rather be the guy helping that guy out. I guess you could consider a SAS on this thing the ultimate preventative maintenance job. lol... That's how I sold it to my wife and just this evening she was asking me, "you get an axle on the way yet?"

Sure!

Sell the Sequoia and buy an 80.

Funny, that. I personally find it easier to do a SAS on a truck that otherwise checks off all your boxes than it is to start with a solid axle truck with no power and not enough interior room. Make no mistake- every time I go off road I always think about how good my 80s were off pavement. But those trucks have too many shortcomings that fail to meet my personal needs; with the Sequoia, it's just one- the front end.

 

[Dindu Nuffin]

It won’t be the same close but not the same.

This is exactly where I was hoping this thread would go. Thank you. How would it be close but not the same, or what makes you say that?

 

[baldilocks]

You said scrub radius is a concern for you. 80 axles have gotta be narrower than the sequoia axles and in that case you’d using wheels with a lot of offset and/or wheel spacers to match the rear axle width.

Have you considered a LC 200? Still IFS but more robust no doubt and I know that Slee has SAS’d at least one. I don’t know a lot about the 200 but if the drop is passenger like every other LC that fact alone would simplify matters and you’d be back into a Land Cruiser.

 

[mudgudgeon]

If I were to get the caster and pinion angles spot on and use the wheelbase measurement to determine where to add the control arm mounts, is it reasonable to expect the 80 front end to behave the same under my Sequoia as it did under my 80s? I'm currently at a 4" lift and don't want to go any higher

I agree with @baldilocks, you're most likely in uncharted territory.

Head to re-read your book to even find your question


You haven't said what your intended use is for the car once modded.

Is it a family tourer? Does it do daily soccer mom duties?
Are you prepared to let the wife loose in it with a car load of kids?
Is it a trail rig?

I'd suggest put the sequoia on a set of scales, figure out weight distribution to front and rear axles of both an 80 and sequoia.

I have no idea how a sequoia compares to an 80 in terms of overall weight, and engine weight etc. But one thing that will have an impact is going to be weight distribution, and unsprung weights.
If you put all 80 front end in, unsprung weight will be the same.
If the sequoia is heavier on the front axle, you'll need to look at spring and shock rates to get it to perform the same.
Even then, a difference in COG, width, length, weight, unsprung weight, spring rates, sway bars etc etc is all gonna play a part.

The higher you lift it, the more likely it is you'll get funky handling.
I'd guess sequoia will be heavier. Most new cars in general are heavier than 30 year old cars of comparable size.

Does 4" lift on the sequoia equate to 4" lift on an 80?
Compare height from ground to underside of frame maybe as a reference point for height comparison.
4" lift on an 80 is putting you into unstable territory IMHO, others will disagree, but there's loads of stories here if rolled, lifted 80's.

By the time you me about cleaning a stock housing so it's a bare housing, then modifying WMS width, you would save a lot of work and pain with a custom housing.

When 100 series where the new kid on the block, a few SAS conversions where done. Not really a viable option for most. Frame rail design is very different for a factory SAS vs factory IFS.
After people came to terms with IFS suspension in the 100s, and realised they still go 98.5% of the places a solid axle 80 would go, the aftermarket took care of some upgraded parts.
SAS just became a "did it because I can" proposition.

 

[BucketEighty]

If it were my project I’d figure out what WMS width I was targeting, where I could fit a steering box, where I could fit a track bar, and I’d start a spreadsheet with a list of axle housing options that have near correct WMS, correct side drop, and steering knuckles that could work with my steering and track bar angles based on my plan and start weighing the time and dollar costs for housing purchase and fabrication hours to make it work.

A radius arm setup is going to handle like a radius arm setup, assuming that you get the arm lengths and angles close. Track bar and steering angles will have a lot of effect on body roll and bump steer and your IFS frame will likely need reinforcement for solid axle steering and track bar mounts and forces. You can’t copy the 80 track bar and steering setup directly because the drop is on the opposite side so track bar bends to clear the pumpkin are all wrong.

What’s your steering and track bar plan and geometry? Share a sketch and some photos.

 

[Broski]

This is exactly where I was hoping this thread would go. Thank you. How would it be close but not the same, or what makes you say that?

Answered in post # 18 & 19