Spicer P8516 Air shift 16 spd.

[Simp5782]

I had a few questions about a transmission I have seen for sale in my area. It is listed a Spicer P8516 16speed air shift. I have googled till I have gone crosseyed looking for the specs on this transmission. And haven't found crap. I emailed the owner to find some other information on what vehicle it is in. I know they came in the old Dodge Bighorn or something along those lines.

I was looking for the specs on the transmission. Like weight, gear ratios in every drive mode. Length, output shaft spline.I know some are cast iron some are aluminum. Esstentially all they are is a spicer 8000 series main box and aux box combined into one.

I think it would be a great transmission to invest in over the direct drive spicer I have now. I watched a video on it and it seemed to be pretty nice shifting transmission.

The guy wants $300 for the transmission, just thinking it could be a good investment to get more road speed in my military truck. Not sure of the SAE housing size either.

http://www.youtube.com/watch?v=BJC47912E_4&feature=player_embedded#!

 

[Diesel_brad]

Not to get off topic, but I am sure glad I live where we have Left have drive. I would be totally F*CK#D if I had to shift w my left hand

 

[RLDSL]

For $300 jump on that sucker like a hound dog on a soup bone!
That is a single stick twin box , in other words it's a 4x4 combination box with a 4 speed main and a 4 speed air shift auxilliary ( brownie) bolted right to it. That type of combination box was also known as an SST at one time and was available as a 5x4 or 4x4 setup
I have full factory service manuals for that box ( and teh other and most all old spicer boxes ) I don't have the diagram sheet for that box with the ratios but they should be the same as the 7000 series manual shift combination, if you had the letter code of teh box, I could tell you what the gear ratios are ( you'd still have to do some math to figure out the final drive ratios between both boxes and your rear )

 

[Simp5782]

This is what the owner replied with.

I do still have the transmission, it has a #1 bellhousing on it, 1 3/4" input shaft and was behind an 8v71 detroit. Very hard to find any info on these transmissions now. It is basically a 4 speed main box with a 4 speed aux attached to it. 1st gear main and 1st aux is the creeper gear. I believe it is an over drive trans set up with a .82 high gear ratio, this is based on where engine rpms were at in high gear with the tire size that was on it. They are considered the p-8500 series of spicer transmissions.


My only issue is the SAE1 bellhousing, but I assume my Spicer 6454 bellhousing would bolt in place of it?

I would love to have it behind my 6.9 I am going to put into my 6x6, w/ its 8.88 ring and pinions plus 53" tires. I would be turning around 2400rpms at 70. Which would come in handy. Over the direct 5 gear 5 speed I have now. Also would help on towing and offroading. Hell if it can handle an 8V71, the IDI will never hurt it.

 

[Simp5782]

Here are some pictures of it.

 

[riotwarrior]

 

[RLDSL]

This is what the owner replied with.

I do still have the transmission, it has a #1 bellhousing on it, 1 3/4" input shaft and was behind an 8v71 detroit. Very hard to find any info on these transmissions now. It is basically a 4 speed main box with a 4 speed aux attached to it. 1st gear main and 1st aux is the creeper gear. I believe it is an over drive trans set up with a .82 high gear ratio, this is based on where engine rpms were at in high gear with the tire size that was on it. They are considered the p-8500 series of spicer transmissions.


My only issue is the SAE1 bellhousing, but I assume my Spicer 6454 bellhousing would bolt in place of it?

I would love to have it behind my 6.9 I am going to put into my 6x6, w/ its 8.88 ring and pinions plus 53" tires. I would be turning around 2400rpms at 70. Which would come in handy. Over the direct 5 gear 5 speed I have now. Also would help on towing and offroading. Hell if it can handle an 8V71, the IDI will never hurt it.

Yes, you could use the SAE bellhousing and clutch/flywheel that you already have. all spicer commercial parts are interchangable

The rear unit OD can be either a .83 or a .805 ( pretty dang close either way ) if its a .83 then the first in teh brownie is most likely a 2.33, 2nd-1.21, 3rd, 1.00, 4th .83 and the main box rev 5.38 1st-5.37 2nd 3.02 3rd 1.73, 4rt 1.00 , thats going by his description that first in the aux is a creeper and it has a .83. there are 3 other possble gear combnations, all fairly close, if it has the .805 od in the aux it will have lower reverse and first in the main but there's also an option of a 1.6 1st in the aux. Now is that all clear as mud?

 

[The Warden]

Sounds cool overall, but I have to ask...how heavy is this tranny, and how heavy is the rotating mass i.e. does parasitic drag have the potential to be a problem?

 

[Simp5782]

See my spicer 6454 is all one piece bellhousing it looks like.But it might split if I remove those nuts from the inside. I am thinking the input shaft being 1 3/4 could be an issue. So i gues the $300 will be a trail and error.My spicer is around 400lbs? i think or close to it. I heard that the air shifts are aluminum and 300 or so. I see it has an overhead mount so I might have to look into that. I dont see the weight being an issue as it used the flywheel housing mounts which was holding a 2000lb multifuel along with the 400lb spicer. vs a 900lb IDI and a 300lb air shift. I think it shouldnt be bad.

 

[RLDSL]

See my spicer 6454 is all one piece bellhousing it looks like.But it might split if I remove those nuts from the inside. I am thinking the input shaft being 1 3/4 could be an issue. So i gues the $300 will be a trail and error.My spicer is around 400lbs? i think or close to it. I heard that the air shifts are aluminum and 300 or so. I see it has an overhead mount so I might have to look into that. I dont see the weight being an issue as it used the flywheel housing mounts which was holding a 2000lb multifuel along with the 400lb spicer. vs a 900lb IDI and a 300lb air shift. I think it shouldnt be bad.

I forgot to mention that I have the manuals for most of teh spicer clutch assemblies as well
You would really want to use a clutch with a clutch brake on that box. It is setup to use a twin disc clutch with a clutch brake ( the clutch brake stops the input shaft while the clutch is engaged in neutral so you can get the thing into gear, it also assists in lining up RPMs for double clutch shifting to get the input shaft spinning at the correct speed. REmember this is a non synchro box. ( after a while youd be shifting it without the clutch anyway )
it's a single countershaft bx so parisitic loss is not bad, weight for the whole combination should be under 740 lbs
Shifting would be without a load, stuff the brownie in dir and drive the main like a 4 speed, but under heavy load, you have deep reduction 1234 in the main, then 2 in teh main and 2nd in teh brownie, then 3rd, 4th on the brownie, then shift up to 3rd on the main while splitting back to 2nd on the brownie , then 3rd , 4rth , then up to 4th on th emain box while splitting down to 2nd on teh brownie, then 3rd, 4th. The air shifts are accomplished by preselecting teh gear on the air shifter when you get up to rpm, then kicking the throttle loose to where the engine unloads the box to let teh rpms drop , while the rpms are dropping the shift will automatically happen as you ease your foot back into the throttle it will finish engaging the gear and then stomp it up to the next split. For downshifting you let the rpms fall and then preselect the gear and back out of the throttle to free the gear and then raise the rpms up to where the engagement point should be gently and it will kick into the lower gear. Very nice boxes. I searched for 2 years to find an air shift brownie for my truck so my wife could drive the thing easier and I finally gave up and had to settle for a second stick.

 

[RLDSL]

For a proper clutch with a clutch brake for that thing, it recomends a 14" twin disc which would be a spicer C2423-39, but that is for use in a full size truck, for what you are wanting to use it in, you should be fine with a 13" twin disc 107003-6 . You can get a different flywheel to match that clutch and your sae 2 bell at any big truck wrecker and if you don't have any good ones nearby, I can direct you to a couple that have that kind of stuff. If you need a different length input shaft thay come in lengths from under 2" to over 23" to fit different applications and they still make them. Spicer boxes are made for commercial use and they have been smart enough to standardize interchange of most important parts , so things like input shafts and yokes and seals etc are very easy to locate at any good heavy driveline shop, and for innards that get too obscure there's always spicer obsolete in Chicago where they have EVERYTHING for all the old boxes ( although they won't sell you a gasket set for one of the old beasts unless it's for a historic restoration because they are very old stock, Spicer recomends Loctite 518 anaerobic gasket maker for all gaskets on older boxes, it works great) but seals are all standard seals that you can get anywhere, as are the bearings.

 

[RLDSL]

Also the bellhousing is removable. You could use teh front half of the sae2 bellhousing that came with your engine but you would need to double check if the rear half that you have is compatible with a clutch brake , It looks like it would be, it has the correct type of actuator, but you would need to check with a driveline shop to make sure, if not you would need to get an SAE2 rear half that is setup for a clutch brake and dual dis clutch setup , but judjing by the thickness of the clutch that came out of that thing, I should think that it would fit.

 

[Simp5782]

It is a Spicer P-8516-4A bill of materials # is 300886-1 s/n 1419037 There is a unlabled # of 418532-C

$250

 

[riotwarrior]

OMG this is sic....ifn only the bronco had a longer wheel base then I could play with ***** like this....but noooo I want a short wheel base rig, ***...oh well, I can turn on a dime!

 

[RLDSL]

It is a Spicer P-8516-4A bill of materials # is 300886-1 s/n 1419037 There is a unlabled # of 418532-C

$250

It *should* have in teh main box
reverse 6.39, 1st 6.53, 2nd 3.42, 3rd 1.86 , 4th 1.00
and in teh brownie should be
1st2.40 2nd 1.19 3rd dir 4th .84

THere;s another possible option but the ratios are so stinking close it wouldnt matter ( as in why they bothered, I don't.... well actually i do know, it's to get perfect half splits when matched to a rear end Took me a while of calculating to figure that one out

I also have a manual that shows the air hose plumbing for those things. THose 4 way air shifters can get interesting

If the price has gone down to $250 jump on that puppy before I fire up my truck and head up there and get it, That is one sweet box