My friend was talking about the transaxle in the 61-63 Pontiac Tempest and it got me to thinking about one of my back burner ideas. The Champ quick change has a 3-1/2" shaft spacing between the pinon and quill shaft. I thought about actually incorporating a transmission onto a quick change to give a car a better balance than the traditional setup with the engine and transmission in the front and a rear end at the back. The Tempest came with a transaxle and independent/ swing axle rear suspension. The idea is to attach to the back of a quick change a transmission with its tail shaft attached to the pinon and the quill shaft extended through the inside of the countershaft of the transmission. At the input side of the transmission, that would be pointed towards the rear of the car, you would put the change box for the quick change gears. The problem that I have run into is trying to find a transmission with the proper shaft spacing. The answer came in the form of the Mopar A833 transmissionon. It has the proper shaft spacing and is good for up to about 500 foot pounds of torque. This was the transmission that they developed to handle the torque of the mighty Hemi in 1964. It comes in a few different ratios and there is also an overdrive version as well. This could be the answer to many types of vehicles. It can be used in most traditional cars and also if someone was doing a mid engine set up in a corvair or other OT car. It could also work in high powered sand rails and such. I have a few champ quick change rears hanging on the wall and am going to persue what it would take to do this. I think that the case of the A833 has the counter shaft offset to the side so I will probably cast a case for it out of aluminum and make use of the internals that can be purchased new. I welcome thoughts on this and it actually fits in the 64 and older parts being used. It also fits with my signature line "Thinking outside the box in a traditional sort of way"
55willys you can get an aluminum case for the 833 from the factory. They had problems with the hole for the countershaft opening up but I seem to remember something about boring out the hole and fitting maybe it was a steel bushing.
That's pretty cool looking. It's mounted upside down and offset because the shaft center of the T10 is 3.03" center to center and doesn't line up with the quick change shafts that are 3.0" on the V8 quick change and 3.5" on the Championship quick change.
Thanks, that's good to know. The reason I was thinking about casting it is that I can incorporate a central lower shaft, an internal shift rail like the corvair and others use and the change box mounting.
Always loved this SD Tempest with PowerShift transaxle https://www.hagerty.com/media/car-profiles/pontiacs-stripped-down-63-tempest-was-super-duty-quick/
I am now looking for an A833/NP440 transmission. Preferably in Washington state. It can be the overdrive or non overdrive, aluminum or cast iron case.
In the 60's there was a guy in Puyallup Wa. named Baker that built rear ends that looked very similar to that. Several very fast sports cars from the NW ran them.
That's sweet! The reason that the transmission is canted is because the shaft centers are different from the quick change. The A833/NP440 transmission has the same shaft centers as the quick change. Having the same shaft centers allows me to be able to run one shaft inside the counter shaft and keep the transmission vertical.
Correct me if I am wrong. You want to run the lower quick change shaft through the center of the transmission countershaft? In other words, a hollow countershaft through which runs a small diameter extended lower quick change shaft. Besides the obvious very limited torque the small diameter shaft would handle, you also have the issue of the splines required on that shaft at the "front" (rear) of the transmission for the quick change gears. And this would be set up as an IRS, correct? Otherwise you'll have huge unsprung weight.
I was looking at the A833 specs and saw that there are at least 4 gear sets including one with overdrive. Then the thought came to me that you could modify the transmission to be like the T5 with an overdrive on the rear of a 4 speed. This could be done with the gears in the overdrive position of the 4 speed overdrive. It could also fit in the space where the change gears would normally be. This would give you a 5 speed transaxle with a change box on the rear. I think that would be quite a good set up for racing and street use.
Yes this would be IRS for sure. The thinking is that I would run a full size 1-1/4" lower shaft through the counter shaft. I would bore out the counter shaft to either accept bushings like the gears on the main shaft have or roller bearings like are in it now. I was also thinking about maybe boring it out and pressing a sleeve in it that would have bearings on the end in the case like some truck 5 speeds do. Then I would just support the extension shaft with bushings inside the counter shaft.
If I'm understanding this right, you're taking drive to an input shaft inside a hollow countershaft, up through the quick-change gears to the first-motion shaft, down through the first-motion gearset, and then up again through the various speed gearsets? The advantages I see are a compact package and you retain the quick-change facility. The disadvantage is that it's still a four-speed, though a hugely strong one, and not the sweetest-shifting one out there. If you forgo the quick-change you could do it a lot simpler, by taking drive directly to the countershaft. You'd need to separate the gear from the first-motion shaft and have it running on a bearing like the speed gears, possibly on a purpose-made longer mainshaft. You'd have to compensate in the ring and pinion ratio for the first-motion gearset (now the 4th speed gearset) ratio times whatever quick-change ratio — which might not be possible. And it would still be a four-speed a bit on the agricultural side. I think the concept might come into its own once you think of it as an auxiliary transmission, to be used in conjunction with something else. At a smaller scale there is a demand for something like this for motorcycle-powered cars, which usually not only need a reverse gear but also an overdrive or two to widen the ratio spread on a vehicle which is probably somewhat heavier than a motorcycle. I don't know if there were 3-speeds related to the A833/NP440: though going the simplified route I outlined above and not doing the first-motion gearset exercise would give you three forward speeds. And if the gearbox is strong enough to handle torque multiplied by, say, a full-manual three-speed automatic with a tall first-gear ratio and a torque converter, you'd have an effective six-speed (or seven-speed) with tight ratios and a fair ratio spread if you count the converter multiplication as a gear. You can dump line pressure as a clutch when shifting the transaxle because you'd be using the converter to launch. Have you considered turning the entire assembly around, so that the 4-speed sits ahead of the axle line? I can think of situations where that might be easier to package. Just a few thoughts off the top of my head.
Ned always like hearing your thoughts on my crazy ideas. I like to think outside the box, I don't think you ever saw the box. I have looked at lots of ways of doing this and even looked at what others such as VW and Ford Pantera. They use an over the top shaft and gear to gear drive on basically the pinion shaft. There is usually no direct drive because even in high gear you are running two gears rather than just coupling two shafts together. There are 3 gear ratios available in the Champ quick change, the tallest being 4.11:1. That is what the change gears are for, to modify the original ratio to what you want. I want to use existing off the shelf parts as much as possible and that is why I am leaning towards the existing A833 transmission. Casting and machining a case are fairly straightforward things to do. There are already couplers designed to work in the shifter style quick change used in sprint cars so coupling shafts is made easier. Making transmission gears and synchros is much harder so existing parts in this area are better. I had thought about using modified change gears with dog clutches similar to my Harley Davidson transmission. It was going to be quite a job to do that and finding a transmission with the right shaft spacing sealed the deal. Another thing I have been looking at is being able to run the shaft above the ring and pinion instead of below. The difference is 7" overall 3-1/2" below the center line and 3-1/2" above it. This would allow for more options when it comes to connect directly to and engine. If you are below the center it would give a low center of gravity but might require the use of a dry sump for clearance. Above it would help with ground clearance such as would be used in a sand rail or such.
I've come back to this idea lately, though I've gone off on a tangent of my own which has taken it far away from a transaxle. It seemed to converge with another idea I had, and in that I had been thinking QC gears, but the helical ones aren't available in the ratios I'd need and there would be the issue of getting synchronizers to work, etc. That got me to thinking if A833 bits might not work. It's a sort of "my dream transmission" exercise: I'd want a fairly tight ratio interval with a wide ratio spread, so six or seven speeds. I'd want clutchless launches via a torque converter, and a clutchless 1-2 shift via an overdrive. The other gears would be engaged using a clutch. I'd also been mulling over the strategy of having the direct ratio, if there is one, somewhere in the middle of ratio spread as explained in the Overdrive!! thread, and been remembering the overdrive approach which @porknbeaner had mentioned a few times before. So, after a bit of mental jigsaw-puzzlery, this is what emerged: we turn our A833 back-to-front. I'm sticking with the A833 for now because we'd been thinking along those lines, but as it turned out this could be done to a lot of other gearboxes as well. The "backwards" A833 won't need a reverse gear, speedometer drive, etc. First off, the upper drop gear is cut off the input shaft and drilled as necessary to ride on a bearing on a new purpose-made mainshaft, or actually two concentric shafts — more on that later. The drop gears become the third ratio of an all-indirect gearbox with reverse-rotation output. The 1st, 2nd, and 3rd gearsets of the "backwards" gearbox become the 4th, 5th, and 6th ratios of the new arrangement. So, we have four selectable gears driving the hitherto stock cluster gear. Now we introduce a second A833, the right way round but upside-down. We cut the cluster gear between the 2nd and 3rd gears (and also between the 2nd and reverse gears — more on that later too). We keep 1st, 2nd, and reverse. We somehow marry the rear part of the mainshaft to the "backward" gearbox's cluster gear, and somehow fix the 2nd gear from the cluster gear solidly to the rear of the new mainshaft. The gearboxes are fixed together front-to-front, with the "upside-down" case shortened as necessary. This is where the concentric mainshafts come in. All the upper gears run on the outer mainshaft, with 2nd fixed to it. The 1st and reverse gears from the "upside-down" part are fixed solidly to the inner mainshaft. We run a torque converter between a clutch and the front of the "backwards" part, with the outer mainshaft driven off the converter housing (i.e. impeller) and the inner mainshaft driven from the converter output (i.e. turbine). That means that the converter is only in play in 1st and reverse; in other gears it's just along for the ride. That also means that the converter may be selected pretty much for its launch characteristics only: no need for lock-up clutches etc. Finally, an overdrive unit is added to the back of the "upside-down" part. It would have to be modified for reverse rotation. In the case of a Laycock-de Normanville/GV unit, the only direction-sensitive component is the unidirectional roller clutch, or sprag. It looks like it should be possible to flip the inner member of this, perhaps after some modification. I'd also want to beef up the hydraulic pressure regulator spring and change the engagement from solenoid to direct mechanical. Because all the gear ratios are somewhat taller than in the transmissions which typically have overdrives behind them, the overdrive would come into its effective RPM range at a lower speed than usual. Assuming two 2.44:1-first A833s, the ratios would be: (overdrive engaged in 6th) I 2.06:1 II 1.50:1 III 1.82:1 IV 0.88:1 V 0.67:1 VI 0.48:1 OD 0.38:1 (overdrive engaged in 1st) I 2.06:1 OD 1.61:1 II 1.17:1 III 0.92:1 IV 0.69:1 V 0.52:1 VI 0.38:1 All of this means that a very short rearend ratio would be needed, something in the order of 5.5:1. That is off-road territory, which is just as well because 4X4 front axles might be a good source for a reverse-rotation rear. Driveshaft RPM becomes a limiting factor, and driveshaft balance becomes critical, though if we assume that we can handle a driveshaft spinning at 12000RPM for short periods, around 175mph could be touched. That opens up possibilities for another idea I'd sporadically been entertaining: inverted portal hubs on hot rods. A 2.88:1 rear driving through 1.92:1 Hummer portals would give us 5.53:1 overall: perfect.
Ned, you have answered the age-old question: Can you think outside the box and inside the (gear) box at the same time? The answer is obviously yes.
Ned, I have looked at other things as well on this. The Richmond 5 and 6 speed transmissions also have the 3-1/2" shaft spacing. The gears are splined onto the counter shaft and there are many ratio options along with being able to replace one gear instead of the whole counter shaft. Another transmission is the Passon A855 which is an overdrive 5 speed based on the A833 4 speed. There is also an Australian built transmission with dog clutch like a motorcycle transmission that bolts directly to the back of the quick change and uses quick change gears as the basis. It's very compact. I have been leaning towards the Richmond 5 speed. The Richmond case split is along the shaft centers so it can have a middle support bearing on the counter shaft. Parts are readily available for it. Casting a case and making a single rail shifter would be fairly straightforward.
I'd forgotten about the Richmond. G-Force make an all-indirect, reverse-rotation 5-speed based on Richmond architecture, so my torque converter idea might work. I'll have to look at tooth counts and such.
Both our ideas would involve inputting power via the cluster gear — in my case turning the Richmond upside-down — and using the drop gears as a speed ratio. In the case of the Super Street OD 5-speed the ratios would be 2.277:1 | 1.458:1 | 1.034:1 | 0.788:1 | 0.611:1. I'd still be able to add an overdrive to the back, giving 0.477:1 and suggesting a 4.56:1 rear. My torque converter idea might even work on your transaxle, if there is clearance under the driveshaft axis and space for concentric shafts past the R&P. The converter would sit in front of the differential.
I was thinking that the transmission would be installed with the input to the rear. The counter shaft would be bored out and a shaft run through the middle of it. This would go to the change box that would transfer the power to the input shaft of the transmission.
Ah. That way you keep the ratios as they are, and retain the facility effectively to change the final-drive ratio easily at a moment's notice, just like with a QC.
Thats exactly what I was thinking. The input shaft would replicate the pinion of the quick change. The main shaft would be short with a coupler to the pinion. There would be an adapter housing to connect the two. A quick change gear housing would be at the back of the whole thing which is the front of a standard transmission. Now too find a cheap used Richmond 5 speed to modify for this. I already have a few quick change housings to work with. Another thing to look at is the the shift location. No matter which way it is put together the shift mechanism is on the right side of the set up. That would fine if I was in a country that drives on the other side of the road. I suppose that the shifter could be centered and it would just be slightly angled. I would like to use a single shift shaft coming out of the trans axle like a Corvair or VW has. I don't really want 3 long external shift rods as they tend to flex and make for a sloppy shift feel.
CHEAP Be careful there, replacement parts aren't as readily available as they once were. Be especially careful with the earlier ones, also have heard that they had their issues.
Yeah, the one I had for the salt car checked out good but ended up being junk, would not stay in gear. I think it is Liberty that does have some parts still?
The Jalopy Journal
