Random 37's fitment / flex shots / ....

[Nay]

Yes, you are correct on the 16x8 +0 which would be 1.5" outward from a centered 8" wheel.

I was running a FJC wheel with 1.25" wheel spacers at approx. 3.75" backspace on a 7.5" wheel (same as a 9" wheel 4.5 BS & a 8" wheel 4" BS) that centered the tread right on top of the wheel bearings. My new wheels are outward 1" from where I was. This has now required me to lower my bump stops.
Does this help?
Sorry this is off topic of Dobinson Tapered & 37s

It’s inportant to not just look at offset. My 17x8.5” -6mm rims are stock backspace, but that means the extra .5” of rim width is all to the outside.

If you went 17x9 in those same specs, you’d be 1” wider to the outside. A 10” rim would be 2” wider.

I would personally stay 17x8.5 since pretty much every 12.5” wide tire specs to 8.5” minimum rim width (understanding that those specs are probably relevant mostly to tire warranty), but wider tires are harder to deal with than larger diameter.

The number one issue most people will face is picking a wider rim when going to 17”, and then having problems with the tire tucking inside the fender lip, and that tuck is critical if you don’t want to lose suspension travel or trim for clearance.

37’s fit diameter wise plenty easily - it’s width and how your suspension travels that determines how cleanly it happens.

I ran 37” trxus on stock rims with 1” spacers no problem and that tire is as big as the STT Pro. But it curves inward and the tread width is only 9” and change so the tuck is completely different than a squared off tread design. It was overall a cleaner fit than the ko2 on 8.5” rims, despite being a full inch larger.

Sticking with 35’s isn’t the issue, it’s that you have to be careful with more variables on 37’s.

Compare this tuck to even the ko2 - it’s much cleaner because the ballon style of the tread angles it inward. As compared to the squared off STT Pro, it’s obvious my backspacing is now not ideal where it was before on the same size max size 37” tire.

That’s the 3.5” F.O.R. Gen II suspension BTW. Here’s the video. The first half being poor spotting and worse driving.



This is also still on F.O.R. Gen II. Some points of good stuff of the ko2 here.

 

[Nay]

This is also the big 37” Trxus on 3.5”. A little secret is not going super long travel. This is a 10” travel shock with the full travel available with 2” bumpstop drops and eye adapters spacing the travel down. All four tires are planted.

Here’s the vid.



Here’s a closeup of the shock as the bumpstop first hits the axle. Notice the near full compression with a little bit of bumpstop compression remaining (shock protected with no wasted travel).

And here we have 50/50 up and down travel and static ride height so one side isn’t on a limiter (bumpstop or full extension) while the other side is still traveling. This is on the 4” Flexi, and perfectly balanced.

 

[Nay]

Took some more pics to test out stuff fit of the Delta VS panhard bracket.

That pesky no flex front end drives me nuts.

 

[Lumpskie]

Took some more pics to test out stuff fit of the Delta VS panhard bracket.

That pesky no flex front end drives me nuts.

View attachment 1751659

Did you take any more pictures of that front flex? I have no reason to ask, other than I like seeing awesome flex like that.

 

[Nay]

Did you take any more pictures of that front flex? I have no reason to ask, other than I like seeing awesome flex like that.

Just that one - was just checking tire fitment on a slag pile. I did look to see if the front end was bound up, and the twist was mostly at the frame end bushings - no bind on the axle end in terms of arms to brackets.

Pretty good in showing how balanced the Flexi is with my shock setup.

 

[GW Nugget]

Sad this thread has nothing to do with Tapered Dobinson coils.... maybe @ccslider should change the title to fitting 37s....
This is all good info though.
You want flex shots?

 

[Nay]

Sad this thread has nothing to do with Tapered Dobinson coils....

Well, unless the question is “Does Dobinson make tapered coils?”, fitment of desired tire size is probably the point .

It’s useful to see how 37’s stuff at different static rides heights and how much choice of rim is a bigger issue than tuning lift height.

That way, if somebody says “Should I run a 3.5” or 4.5” suspension to clear 37s?” we can answer “Yes” and then suggest care be taken on backspacing and tire/rim width as well as shock travel for desired suspension performance.

Inasmuch as it matters, if I swapped from Dobinson 4” Flexi to Dobinson tapered, I’d have Dobinson tapered instead of Dobinson Flexi and my suspension would be tuned to 4” up travel and 6” down instead of 5”/5”.

I would find that to be somewhat less balanced because some down travel would be happening while the other side was on a limiter, but no swapping of tires would fix that.

As a side note, it looks like BORA is willing to build me .75” spacers through Custom Wheel Offset to deal with not having the hub centric ring that makes those spacers unusable for us, at no extra cost.

Not about coils, but that will dial 37x12.5” tire tuck on a 17x8.5 -6mm offset rim with a net 3.75 backspace. Thems important things to know when one doesn’t want to lose suspension travel arbitrarily to bumpstop drops, or break out the trusty sawzall, just because a certain net backspace is difficult to achieve.

I could drop my stops another 3/8” or so and take care of any remaining rubbing, but then I am tossing suspension travel I worked hard to dial exactly as I want it into the trash. So new spacers it is.

 

[baldilocks]

Well, unless the question is “Does Dobinson make tapered coils?”, fitment of desired tire size is probably the point .

It’s useful to see how 37’s stuff at different static rides heights and how much choice of rim is a bigger issue than tuning lift height.

That way, if somebody says “Should I run a 3.5” or 4.5” suspension to clear 37s?” we can answer “Yes” and then suggest care be taken on backspacing and tire/rim width as well as shock travel for desired suspension performance.

Inasmuch as it matters, if I swapped from Dobinson 4” Flexi to Dobinson tapered, I’d have Dobinson tapered instead of Dobinson Flexi and my suspension would be tuned to 4” up travel and 6” down instead of 5”/5”.

I would find that to be somewhat less balanced because some down travel would be happening while the other side was on a limiter, but no swapping of tires would fix that.

As a side note, it looks like BORA is willing to build me .75” spacers through Custom Wheel Offset to deal with not having the hub centric ring that makes those spacers unusable for us, at no extra cost.

Not about coils, but that will dial 37x12.5” tire tuck on a 17x8.5 -6mm offset rim with a net 3.75 backspace. Thems important things to know when one doesn’t want to lose suspension travel arbitrarily to bumpstop drops, or break out the trusty sawzall, just because a certain net backspace is difficult to achieve.

I could drop my stops another 3/8” or so and take care of any remaining rubbing, but then I am tossing suspension travel I worked hard to dial exactly as I want it into the trash. So new spacers it is.

Semantics matter..... seriously.

 

[Box Rocket]

I've been going back and forth on 37's for years. Honestly if I could find any that fit 16" wheels I'd probably make the jump, but nearly every 37 on the market is for 17" wheels or larger and I'm not looking to buy new wheels too in order to make it happen. Besides that, my truck has done very well with 35's over the years. There has only been a couple times I can think of that tire size was the thing that held me back on an obstacle offroad. That said, I like the look of 37's, I just haven't felt the "need" for them.

Radius arms can limit flex but I wouldn't call them "bumpstops". They'll only limit things in cross axle articulation. If you stuff both front tires (like when driving fast) they won't limit at all and bigger tires can rub hard with certain suspension setups that don't use bumpstop extensions. Grinding (narrowing) the front eyes of the radius arms can help, but bushings will wear quicker if you're flexing it out a lot.

There is a 3" suspension kit available with tapered coils and full 12" shocks that will fit 37's without front bumpstop mods and a 2" over stock bumpstop in the rear. Adding the plates to relocate the rearmost radius arm bolt 1" forward is a useful and pretty simple way to improve tire/firewall clearance and it will straighten out the coils that normally get a bit of bend in them when lifting with stock radius arms.

I have 16x8" wheels with 35mm BS (-12 offset IIRC) and I'm also running 1.5" spacers. Fronts with my 35's don't rub but if fully stuffed hard in the rear the tires will rub slightly on the flares. A little trimming to the inside edge of the flare takes care of most of it. Removal of the flare would probably eliminate all rubbing but I like the flares.

IMG_0630 by Adam Tolman, on Flickr

Light rubbing on this stuff back tire. With 37's there would be more rubbing on the top arch of the flare and probably a bit at the back of the wheel arch. Note: I have 3/4" longer lower control arms.
IMG_0634 by Adam Tolman, on Flickr

 

[ccslider]

Sad this thread has nothing to do with Tapered Dobinson coils.... maybe @ccslider should change the title to fitting 37s....
This is all good info though.
You want flex shots?
View attachment 1752792 View attachment 1752795 View attachment 1752798

I ordered a dobinsons 3 inch tapered and was wondering if anyone has that lift and 37s. It was already answered that it's not enough without lots of bumpstops, and more lift with good backspacing on the rims. I abandoned the whole 37 idea for now.

Now everyone is just using this thread to post flex shots, nothing wrong with that.

 

[Nay]

If you stuff both front tires (like when driving fast) they won't limit at all and bigger tires can rub hard with certain suspension setups that don't use bumpstop extensions.

There is a 3" suspension kit available with tapered coils and full 12" shocks that will fit 37's without front bumpstop mods

These two pieces don’t agree with each other, unless you want to use the shocks as jounce bumpstops.

Let’s do this with pictures and math.

For full axle compression on both sides, meaning “bottoming out”, where the tires move straight up and do not angle into the wheel well to stuff, there has to be more tire to fender clearance than shock travel.

6” > 5” so my tires won’t compress straight up and hit my fenders. I could lower the lift and inch or 2 or whatever and this stays true.

So are the shocks protected? 2” bumpstop drop. On flex with some bumpstop compression the bumpstops leave about 3/8” of shock remaining. Straight up flex leaves more travel to the bumpstop since the axle is not coming in at an angle. Here I am barely protected.

This is a 10” travel eye to eye shock. 26” extended, 16” compressed, which is the standard 10” travel eye to eye shock that virtually everybody makes in the exact same specs. Here is the upper eye mount adapter.

Look at that nice burley swingarm mount instead of forcing a pin against a bushing. And no pin style bushing flex. And you can use any shock you want in any valving because it doesn’t have to be specific to your springs. You don’t even have to ask permission.

Weird, huh?

 

[Box Rocket]

These two pieces don’t agree with each other, unless you want to use the shocks as jounce bumpstops.

Let’s do this with pictures and math.

For full axle compression on both sides, meaning “bottoming out”, where the tires move straight up and do not angle into the wheel well to stuff, there has to be more tire to fender clearance than shock travel.

View attachment 1753717

6” > 5” so my tires won’t compress straight up and hit my fenders. I could lower the lift and inch or 2 or whatever and this stays true.

View attachment 1753718

So are the shocks protected? 2” bumpstop drop. On flex with some bumpstop compression the bumpstops leave about 3/8” of shock remaining. Straight up flex leaves more travel to the bumpstop since the axle is not coming in at an angle. Here I am barely protected.

View attachment 1753719

This is a 10” travel eye to eye shock. 26” extended, 16” compressed, which is the standard 10” travel eye to eye shock that virtually everybody makes in the exact same specs. Here is the upper eye mount adapter.

View attachment 1753720

Look at that nice burley swingarm mount instead of forcing a pin against a bushing. And no pin style bushing flex. And you can use any shock you want in any valving because it doesn’t have to be specific to your springs. You don’t even have to ask permission.

Weird, huh?

Depends on the shocks specs and if your shocks have internal hydro bumps. But thanks for the math lesson.

No tire rub, full stuff both sides, stock bumpstops. Of course, as I mentioned earlier I'm on 35's not 37's so I believe 37's would rub the flares, but no flares probably no rub.
IMG_8009 by Adam Tolman, on Flickr

 

[Nay]

And now the front.

6” > 5” so we’re good on fender clearance.

Note the dirt on the bottom of the shock ^^^. It was compressed recently down to 1/2” remaining travel.

2” extended front bumpstop. There is 4” of travel to the bumpstop, but this is a jounce bumpstop unlike the rear. We can see I have compressed the bumpstop 1/2” last first contact to have as much shock compression as the clean piston shaft shows. So this extra 1” of available extension is measured correctly for a bottoming our type hit.

Here is the upper eye adapter dropping the top shock mount.

And here is the lower eye adapter raising the lower mount (both compression the shock) at static ride height.

I still run stock brakelines, because I haven’t added unnecessary travel just by being a slave to inferior pin style OEM shock mounts.

Everything fits on a 37. I use Landtank caster plates with stock unmodified radius arms, my front coils have no bow, my tie rod doesn’t have radius arm clearance issues.

My suspension is 50/50 travel balanced, in the sweet spot of the coil travel, which is optimal. My shocks cost $800 and my springs cost $550.

37’s vs. 35’s is nothing more than choosing less rubber. Everything else you should be doing is identical.

 

[Box Rocket]

Another 80 with 37's, flares, 3" suspension no front bumpstop mods, full 12" travel shocks. Does it rub? it might a little, but if your tires don't rub you can fit bigger ones, right?

@Nay, not saying you're wrong, but it's not universally the same for every setup.

 

[Nay]

Depends on the shocks specs and if your shocks have internal hydro bumps. But thanks for the math lesson.

Math on a Friday is always fun. Clarifying that you have spent a mint on shocks with internal hydro bumps is probably important for the average reader that we are creating archival crap to read. Let’s scan in here:

It looks like 37’s would be difficult as you have too much up travel to fit them, but maybe not. Up travel limiters are up travel limiters so long as you don’t implode them.

That math stuff I just did would work for you, though. How about a tape measure picture of tire to flare and then static shock travel.

Subtract 1” from the tire to flare measurement for 37’s and then we’ll know whether or not “there is a 3” lift on the market that fits 37’s without front bumpstop drops”.

Not that bumpstops are a big deal, it’s just a shame to lose suspension travel design to them.

 

[Box Rocket]

Math on a Friday is always fun. Clarifying that you have spent a mint on shocks with internal hydro bumps is probably important for the average reader that we are creating archival crap to read. Let’s scan in here:

View attachment 1753741
It looks like 37’s would be difficult as you have too much up travel to fit them.

That math stuff I just did would work for you, though. How about a tape measure picture of tire to flare and then static shock travel.

Subtract 1” from the tire to flare measurement for 37’s and then we’ll know whether or not “there is a 3” lift on the market that fits 37’s without front bumpstop drops”.

Another useful math point for readers would be how much costs.

Yes I said that 37's would probably hit the flares at full stuff on both sides with my setup. Without flares, I don't think so.

I didn't realize that there was a cost limit that needed to be considered in this discussion. The question being about fitment, there is an option but yes, it won't be the cheapest option.

 

[Nay]

Yes I said that 37's would probably hit the flares at full stuff on both sides with my setup. Without flares, I don't think so.

I didn't realize that there was a cost limit that needed to be considered in this discussion. The question being about fitment, there is an option but yes, it won't be the cheapest option.

There’s no cost limit, but it’s an important data point for most people. I’m just addressing what seems to be a common misconception that you have to do something (or anything) different to fit 35’s vs. 37’s.

The vast majority of people on 35’s have enough lift to have corrected caster, adjusted panhards, and longer (or eye adapter spaced down) shocks that they should be using longer bumpstops to protect.

If you want to run 37’s, you are going to correct caster, have adjustable panhards (or the better Delta raised bracket solution in the rear), and longer (or eye adapter spaced down) shocks that you are protecting with bumpstops.

Both 35’s and 37’s are typically 12.5” wide, so rim backspace and width considerations are essentially the same for both sizes. I rubbed more with the wide 35” Toyo MT than I did with 37” Trxus on the exact same suspension.

When I worked with Frankie to develop the F.O.R. suspension a decade ago, we agreed that the principle was a 3” lift optimized for 35” tires. My pics of shock travel using eye adapters and bumpstops to align each point of travel are the baseline outcome of that design principle.

What I realized fairly quickly was that same design principle fit 37s. So I put on 37s without modifying anything else and ran it that way for a decade. When my F.O.R. suspension was damaged in an accident last Nov, I could have run Slinky, Slinky HD, Dobinson’s tapered, Dobinson’s Flexi 3”, Dobinson’s Flexi 4”, whatever.

Because a coil spring does nothing to set suspension travel.

The only question is if that coil spring is operating effectively across the full range of travel. I went with 4” Flexi because the 80 is so perfectly aligned at 4” and its big ass needs more clearance.

That and $275 for a set on Amazon Prime vs. backorders and higher prices for tapers and whatnot.

 

[Box Rocket]

There’s no cost limit, but it’s an important data point for most people. I’m just addressing what seems to be a common misconception that you have to do something (or anything) different to fit 35’s vs. 37’s.

The vast majority of people on 35’s have enough lift to have corrected caster, adjusted panhards, and longer (or eye adapter spaced down) shocks that they should be using longer bumpstops to protect.

If you want to run 37’s, you are going to correct caster, have adjustable panhards (or the better Delta raised bracket solution in the rear), and longer (or eye adapter spaced down) shocks that you are protecting with bumpstops.

Both 35’s and 37’s are typically 12.5” wide, so rim backspace and width considerations are essentially the same for both sizes. I rubbed more with the wide 35” Toyo MT than I did with 37” Trxus on the exact same suspension.

When I worked with Frankie to develop the F.O.R. suspension a decade ago, we agreed that the principle was a 3” lift optimized for 35” tires. My pics of shock travel using eye adapters and bumpstops to align each point of travel are the baseline outcome of that design principle.

What I realized fairly quickly was that same design principle fit 37s. So I put on 37s without modifying anything else and ran it that way for a decade. When my F.O.R. suspension was damaged in an accident last Nov, I could have run Slinky, Slinky HD, Dobinson’s tapered, Dobinson’s Flexi 3”, Dobinson’s Flexi 4”, whatever.

Because a coil spring does nothing to set suspension travel.

The only question is if that coil spring is operating effectively across the full range of travel. I went with 4” Flexi because the 80 is so perfectly aligned at 4” and its big ass needs more clearance.

That and $275 for a set on Amazon Prime vs. backorders and higher prices for tapers and whatnot.

I totally agree that the work involved to fit 35's is more or less the same work to fit 37's.

 

[Nay]

We need a good meme for any time somebody asks about running 35s.

 

[jfz80]

via Imgflip Meme Generator