Front Propshaft: Stock SyTy vs "Bravada"

[DaveP]

In another thread today, a member posted pics of a "Bravada" shaft he found while junkyarding. I at first called it a SyTy, but upon further discovery admitted I was wrong, and he actually found an AWD front shat I hadn't seen before.

Enjoy:
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Here's a Stock SyTy shaft:










Here's what I'm going to call "Early Bravada" as I've seen this 2" tube version in 1990-1994 Bravadas:










And the "atomicmecha" shaft: Note that the sizes of the front C/V and u-joints appear to be the larger sizes found on the "early" shaft. Hopefully he will provide the dimensions, and the YEAR of the Bravada he found this in. The small tube diameter is perfect for shifter bracket clearance on a SyTy.

I just had a thought. I know 2nd Gen Jimmys have floor shifts. If Bravadas do too (I don't know for sure), this is the reason for the small tube diameter. Shift linkage clearance. Just like on SyTy. 90-94 1st Gen Bravadas have column mounted shifters, so the larger tube can be utilized.

 

[BMFB]

Re: Front Propshat: Stock SyTy vs "Bravada"

Re: Front Propshat: Stock SyTy vs "Bravada"

I might be digging for one of those this summer

 

[Black Knight]

Re: Front Propshaft: Stock SyTy vs "Bravada"

The last shaft I pulled out of a Bravada looked like the atomicmecha shaft, I know for certain it wasn't the 2" version. I didn't even notice any of the differences between them so I was always was under the impression the SyTy and Bravada shafts were identical.

 

[V8 Sonoma GT]

Re: Front Propshaft: Stock SyTy vs "Bravada"

there is another style too for bravadas anyway, i got this off a 91 bravada, and sold to another member, randy i think, any ways, you can see it looks closer to the stock one...

we also may want to consider any of these could have been a 1 off, made by a driveline shop...


BTW my 94 brav has the one daveP posed, with 1 square, and 1 circle end...

 

[Don W.]

Re: Front Propshaft: Stock SyTy vs "Bravada"

we also may want to consider any of these could have been a 1 off, made by a driveline shop...

If so or even if not grab it if you see it because having a shop build a CV shaft is flippin' expensive. Technically our trucks need a CV joint at each end because the two angles are different AND not parallel with each other.

From http://www.drivelinespecialist.com/Tech1.htm

Double Cardan is a term used when describing a one piece drive shaft with three (or more) universal joints. What a double cardan will do, is split a universal joint operating angle into two separate angles that are exactly one half of the original angle. Normally a Double-Cardan (a.k.a. Constant Velocity or CV) style drive shaft is used in applications where it is not possible or practical to properly align the ends of a drive shaft for a single-cardan setup. Examples include where the operating angle would be too great over a single cardan joint a double-cardan allows the operating angle to be split across the two halves of the joint. It is also possible to use two CV joints on a drive shaft which is commonly used where it is not possible to align either end of the drive shaft, such as when both vertical and horizontal mis-alignment occur, or when mis-matched operating angles are present, such as in front wheel drive vehicles.... Drawbacks of multiple CV joints are their higher cost and complexity as compared to u-joints, their extra length and weight, and their decreased maximum operating angle limitations.

That's why you will always feel some vibration with a "Gilbert" shaft conversion which uses only one joint at each end. Some will feel it, others won't, wrong kind of butt in the seat I guess... :rotf:

Actually I thought CV joints allowed for a greater angle not less but I didn't research that.

 

[DaveP]

Re: Front Propshaft: Stock SyTy vs "Bravada"

That's why you will always feel some vibration with a "Gilbert" shaft conversion which uses only one joint at each end. Some will feel it, others won't, wrong kind of butt in the seat I guess...

For years I've felt like the Lone Ranger on this. Thank You for bringing this up, I've given up. I agree, there's a lot of poorly-calibrated butt dynos running Gilberts on here that don't feel vibration, but it has to exist if driven at highway speeds. It's engineering fact.

I know for fact the single-joint at each end shafts must vibrate at high speeds (70+ MPH) because my DD 91 pick-up 4X4 does when the front axle doesn't disengage, and I resume highway speeds.. It has a single cross-joint at each end, like a Gilbert, and being an S-Series, it has the same driveline angles as a SyTy.

Generally, the difference in angles at each end must have <1º difference for vibration-free running.

Thanks for the input.

 

[JSM]

Re: Front Propshaft: Stock SyTy vs "Bravada"

I don't disagree from an engineering standpoint of why a CV is used. From an experience issue I have had several CV's explode though, and even with my truck running 140 mph did not notice any "extra" vibration beyond normal. Granted my truck normal vibration is not stock and I am sure the lack of CV doesn't help that. At the same time having a bit more confidence the shaft isn't going to try to occupy the same seating position as me is worth it.

Of course at this point on jack stands, it is all mute.

 

[V]

Re: Front Propshaft: Stock SyTy vs "Bravada"

'96 Bravada here. Floor shifter.

If my memory is correct, I have the same propshaft as atomicmecha.

 

[atomicmecha]

Re: Front Propshaft: Stock SyTy vs "Bravada"

Took some measurements today of the one I pulled from a 96+ bravada. Dont know the exact year but it was the jelly bean body style.

This is the diff flange:

This is the t-case end:

And the other measurements.

I need to pull the front shaft out of my typhoon this weekend to shave part of it down. It rubs the linkage like crazy. Its a replacement shaft to the one that snapped on me back in September of 2013. I'm guessing this one will fit. I'll know more this weekend.

 

[atomicmecha]

Re: Front Propshaft: Stock SyTy vs "Bravada"

Oh and this bravada had a floor shifter.

 

[V]

Re: Front Propshaft: Stock SyTy vs "Bravada"

I might be wrong, but I think there is a difference at the flange (bolt pattern). If it doesn't work, I might be interested in buying it from you.

 

[Don W.]

Re: Front Propshaft: Stock SyTy vs "Bravada"

I'd be willing to bet these are all "hub centric." Not bolt centric. So the bolt circle (so the bolts fit) and the hub circle (so it's on center) will be vital if it's gonna get changed. Look at the second pic above. The dimension between 1 and 4 on the tape is, roughly, the hub circle.

Edit: Looking again the second pic the two extra holes might be for dowels which would align things as well.

 

[V]

Re: Front Propshaft: Stock SyTy vs "Bravada"

The 4472 and front differential on the '96 & '97 Bravada have different flanges from the SyTys. Below are my rough measurements from under the truck:

You can see that the flange has a shadow of the two extra holes from the propshaft, but there are no alignment dowels.

Front diff: squared-off flange, but the diameters and bolt spacing are the same as the transfer case.


Compare the above to a '93 propshaft:

 

[Sy644]

Re: Front Propshaft: Stock SyTy vs "Bravada"

Speechless. So what's year bravada and type of shifter floor or column best for syty? Stronger than stock syty? What about modify shifter bracket?

 

[atomicmecha]

Re: Front Propshaft: Stock SyTy vs "Bravada"

Finally got around to taking my typhoons front propshaft back out (and turns out thats not the only thing rubbing cause the squeak is still there when driving) and compared it to the one I took out of the late model bravada side by side. I know its already been established that the t-case mount is different, but just wanted to share some more photo's illustrating this with both shafts next to each other.

Atleast they are the same length...

And the front differential mounts are identical (wonder if this confirms that the front diff's will work in our trucks?)

Here's where the issue is...

Wonder if you could just swap the flange on the t-case? Like pull one off the t-case of the late model and put it on the stock t-case?

 

[DaveP]

Re: Front Propshaft: Stock SyTy vs "Bravada"

Wonder if you could just swap the flange on the t-case? Like pull one off the t-case of the late model and put it on the stock t-case?

I think you can. I highly doubt the splines are different. The trick is of course to find a flange. 2 years only.

Since beginning this thread, I too have obtained one of these 96-97 Bravada shafts and seen the different T-case flange diameter that V confirmed above. I found a 97 Bravada in pick a part a few weeks ago, and when I went back a couple of weeks later, I took a socket to grab the flange, but the truck was gone. So I can't really use it without the flange.

I probably won't pursue making the 96-97 shaft work in any of my trucks, as I have (2) 93-94 2" tube Bravada shafts in my stash which are bolt-ins, and more than adequate for the power levels my trucks produce.

 

[DaveP]

Re: Front Propshaft: Stock SyTy vs "Bravada"

Technically our trucks need a CV joint at each end because the two angles are different AND not parallel with each other.....That's why you will always feel some vibration with a "Gilbert" shaft conversion which uses only one joint at each end. Some will feel it, others won't.....

I....even with my truck running 140 mph did not notice any "extra" vibration beyond normal.

I had some time to try a little experiment with DesertSy today.

Ever since I began driving this truck, it has had a fairly noticeable vibration in the maybe 6 to 10 hz range between 40-45 MPH. The first thing Paul-Z commented on when he got out of it the first time he drove it was "what's the vibration at 45MPH?". More recently I was having some fun with it and was into the 90-110MPH range. It went into a fore-aft pitching moment that was fairly violent, and concerned me as far as control issues.

It had the"Gilbert" style single cardian front joint propshaft that came with the truck pictured below. I believe this is actually a stock propshaft that has had the front joint replaced with a slip-yoke style yoke and flange with a single joint, and not a true "Gilbert".

I installed a stock propshaft today and went for a drive, and the vibration at 40-45 that has been there since the beginning is GONE. I haven't tried the 90-110 blast yet. Maybe I'll let Paul test that for me. I don't care what you guys say now. I have empirical evidence that the single front joints DO vibrate more than stock shafts. In DesertSy by quite a bit. I proved it with back-to-back testing.

The solution for me is going to be the 2" 92-94 Bravada shaft for my SyTy's that need a replacement. I have 2 in inventory, and will always be on look-out for more. The parts to service these are available, and reasonably-priced.





Enjoy.

 

[JSM]

Re: Front Propshaft: Stock SyTy vs "Bravada"

I can't argue with your test thats for sure. Glad to see someone do a back to back test.

 

[Logan]

Re: Front Propshaft: Stock SyTy vs "Bravada"

So this shaft pictured is some form of after market shaft? The reason I ask is because this is what was in my Ty when I bought it. I had a horrific vibration that was solved with new U-joints. If someone could fill me in on the specifics with this thing I would appreciate it.

 

[Brwndrvr05]

Re: Front Propshaft: Stock SyTy vs "Bravada"

I had one made up at a local driveline shop and it looks just like the one pictured above but a bit thicker and its also telescopic. I also get some vibes from it and at about 45mph and higher its very noticeable. Shaft is all brand new with HD Spicer joints and fully balanced. Is this normal with these heavy duty shafts?