Beefing up A500 overdrive

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Headintheclouds

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I have read a few articles that suggest the overdrive on a 42RH can be rebuilt to be as strong as that on a 46RH. The larger part of this seems down to fitting more clutches and steels. It seems there are different thicknesses of these but also at least 3 different designs of direct clutch drum allowing varying space for clutch components.

If it's an easy upgrade I would have expected A518 direct clutch drums to be readily available. I have seen a few after market drums advertised but none from the usual suspects - Sonnax, Transgo etc.

Is it as simple as just changing clutch drum and frictions / steels / pressure plates etc? If so, does any reputable company make a kit including the drum? Otherwise any recommendations for a decent quality drum?

If I were in the States I would probably look for an overdrive from a 46RH but it's both difficult and pricey from across the Atlantic
 
Precision Transmissionshas a series of Youtube videos that cover the 47 and 48 series trans and upgrades . He does mostly diesel stuff but from what I understand internals are similar.
 
Well the 42 is 904 based, so it is not quite that simple, "I bet." Just for kicks, I saved the 4?E out of the V10 donor parts truck, tho it is a 4WD version. Might be some parts in there............(for 518 series)

I know one thing .....the converter out of that thing is HEAVY, and has 8 bolts, not 4
 
The 42 is 904 based but my understanding is that the overdrives on the hydraulically controlled transmissions are interchangeable and very similar. Part of the reason I went for the 42RH is that torque converter and bellhousing are a fair bit smaller and lighter than the 46
 
How much power? You can upgrade the OD section of an 42 or 44 to 46, 47 or 48 OD internals. But, the OD on an RE/RH transmission costs a lot of power, and increasing pinion and clutch count requires careful consideration based on what you're trying to accomplish.

The front portion of that transmission you're stuck with the smaller input assembly and intermediate shaft, which will be your weak link with more power or forced induction.
 
67Dart273 said:
Well the 42 is 904 based, so it is not quite that simple, "I bet." Just for kicks, I saved the 4?E out of the V10 donor parts truck, tho it is a 4WD version. Might be some parts in there............(for 518 series)

I know one thing .....the converter out of that thing is HEAVY, and has 8 bolts, not 4
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47RE behind a v10 (same bell housing as a diesel 47).
 
Duster346 said:
How much power? You can upgrade the OD section of an 42 or 44 to 46, 47 or 48 OD internals. But, the OD on an RE/RH transmission costs a lot of power, and increasing pinion and clutch count requires careful consideration based on what you're trying to accomplish.

The front portion of that transmission you're stuck with the smaller input assembly and intermediate shaft, which will be your weak link with more power or forced induction.
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when you say "costs a lot of power" how much are the losses on a 500/42 RH?

I'm looking to go this route with a 375hp LA that will either see injection or swap to a G3 down the line. what would be the best course of action- building out an OD unit or go with a gear vendors unit?

currently has a 727 and I'm not racing it
 
Not crazy power. 318 poly with 4 barrel Edelbrock. Probably about 250BHP 350lb torque. This is within the original spec of the 42RH but I would like to give myself a bit more leeway for freeway use. The car is being set up for comfortable touring but keeping decent performance.

Most of the control setups for retrofit overdrive drop it out on fairly light throttle. The PACT solution with a vacuum switch and 2 pressure switches drops both lockup and overdrive in one go as the vacuum drops which I don't want.
I plan to have the lockup drop out by vacuum on fairly light application of throttle but have the overdrive held on through a microswitch on the linkage. This should mean I can stay in overdrive for relatively gentle overtakes on the freeway and not have a sudden increase in revs.

If I'm rebuilding the transmission anyway it makes sense to me to upgrade at least to 44 spec. if not 46. I wasn't aware of any real down side so please tell me if I have missed something.

I haven't had the transmission apart yet but I'm guessing my 42RH has 2 steels and 3 friction in the overdrive and 8 lined and 7 steels direct. Upping to 46RH spec would be 3 steels and 4 friction overdrive and 10 lined and 9 steel direct.
 
Do you have a link to the PACT solution?
 
Thanks. I thought that was for the A-500
 
rumblefish360 said:
Thanks. I thought that was for the A-500
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I think they have one for the 500/42 as well, I just happened to have that one at the ready.

it seems that you and I are kinda sorta headed in the same direction transmission wise...
 
I just need some information as to start setting up the ducks. I’m a bit deficient in this area. I’ve been running a manual 4spd for decades. I’m just starting in with automatics.
 
rumblefish360 said:
I just need some information as to start setting up the ducks. I’m a bit deficient in this area. I’ve been running a manual 4spd for decades. I’m just starting in with automatics.
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same here, gatherings of informational stages. I only wanna do it once, and pretty much made up my mind on the 500/42 due to less parasitic loss, not needing a unit to handle big hp/tq numbers and the fact that I can mate it to a G3 down the line if I so choose.

I just want to build the best possible piece and get all the parameters right the first time around.
 
Oh hell yea! I just wanna do a nice cruiser with a small cam, well, tiny cam really. Something easy on fuel that can run all day across the country & enjoy.

I’m also paying attention to the currently running max mileage 318 thread.

318 MAX fuel economy builds?
 
I picked up an A500 to go behind my 6.4 crate (485hp/475tq) and had Dave Smith at Pro Trans beef and build it up. He swapped in quite a few parts. I looked around for lockup converters and found there are only a few companies that will make them up. I ultimately went with Edge Racing Converters for a billet unit. As for the PATC kit to have a fully auto OD and lockup, theirs is listed for the A518 only. I purchased the kit anyway after speaking with one of their techs. The difference I found is that the A518 hydraulic ports are 1/4 NPT vs the A500 1/8 NPT. The kit has 1/4 NPT pressure switches (I opted for the adjustable version). I picked up a couple of brass adapters and will use 1/8 copper tubing to place the switches in the engine bay for access and tuning. My swap won't begin until next year as my 390 stroker/904 w/EFI are barely broken in so my future road trip plan won't be pushed back. This is in a 68 Coronet wagon.
 
I love it when people talk about power losses in automatic transmissions. You could easily drive one with a Briggs and Stratton single cylinder engine. It wouldn't pull a lot of weight, but the transmission would function fine.
 
RustyRatRod said:
I love it when people talk about power losses in automatic transmissions. You could easily drive one with a Briggs and Stratton single cylinder engine. It wouldn't pull a lot of weight, but the transmission would function fine.
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I don't. I've been asking questions about this very subject regarding different transmissions (both auto and stick) and am getting absolutely nowhere. I'd still like to know these things "just because".
 
volaredon said:
I don't. I've been asking questions about this very subject regarding different transmissions (both auto and stick) and am getting absolutely nowhere. I'd still like to know these things "just because".
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You might want to check out John Cope Racing. Not exclusively Mopar but he covers them a lot. Good stuff. He has tons of stuff on youtube and I bet he takes phone calls.
 
Headintheclouds said:
Not crazy power. 318 poly with 4 barrel Edelbrock. Probably about 250BHP 350lb torque. This is within the original spec of the 42RH but I would like to give myself a bit more leeway for freeway use. The car is being set up for comfortable touring but keeping decent performance.

Most of the control setups for retrofit overdrive drop it out on fairly light throttle. The PACT solution with a vacuum switch and 2 pressure switches drops both lockup and overdrive in one go as the vacuum drops which I don't want.
I plan to have the lockup drop out by vacuum on fairly light application of throttle but have the overdrive held on through a microswitch on the linkage. This should mean I can stay in overdrive for relatively gentle overtakes on the freeway and not have a sudden increase in revs.

If I'm rebuilding the transmission anyway it makes sense to me to upgrade at least to 44 spec. if not 46. I wasn't aware of any real down side so please tell me if I have missed something.

I haven't had the transmission apart yet but I'm guessing my 42RH has 2 steels and 3 friction in the overdrive and 8 lined and 7 steels direct. Upping to 46RH spec would be 3 steels and 4 friction overdrive and 10 lined and 9 steel direct.
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In your case, 250hp 318 poly, the stock A500/42rh will work very well. Remember, they were designed for a truck weighing much more than your car. I have a slightly warmed up 318, probably about 250hp with a stock rebuild A500 (1990 V8 truck trans) and 3.91 gears. I love the combo. Been driving it for maybe 5 years now and I put lots of miles (highway, cruise, and occasional drag strip). I understand wanting to overbuild, but maybe not necessary.

Cley
 
As far as I'm aware most of the loss in auto transmissions is in the torque converter. Lock up pretty much fixes that.
Overdrive gets the engine working at the most efficient part of the power band but is subjected to high torque at lower revs. This is why I'm looking to strengthen the overdrive, not because I have crazy horsepower.
 
I didn't post what I did to derail the thread.
That said, I'll just add that I thought it was centrifugal force to get all the rotating parts, well, rotating with the added resistance of being immersed in fluid. The lock up doesn't come on til the trans has shifted to it's highest gear, it's the initial takeoff and power eaten by the trans in getting up to that speed, where the lock up can do its thing
 
volaredon said:
I didn't post what I did to derail the thread.
That said, I'll just add that I thought it was centrifugal force to get all the rotating parts, well, rotating with the added resistance of being immersed in fluid. The lock up doesn't come on til the trans has shifted to it's highest gear, it's the initial takeoff and power eaten by the trans in getting up to that speed, where the lock up can do its thing
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It didn't occur to me that you had. Very fair points. I wasn't considering stick but comparing 727 to 42RH so the only real difference is the overdrive.
The car isn't a daily driver and will mainly do longer journeys so lockup should give a real benefit.
 
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