PT81Jan Posted January 24, 2016 Report Posted January 24, 2016 Hey, my name is Jan and I am new here in that forum. I hope someone can help me regarding my questions: I would like to equip the differential of my 1939 Plymouth PT81 Pickup Truck with an other ring and pinion gear to reduce the rpm of the motor, but I am not quite sure which part No.`s fits to my differential. I have seen that this topic was discussed before, but I could not find closer information about the correct specification to my diff.. I am from Germany and information about Chrysler part No.`s of that time is not easy to get here (despite internet ...). I have sent requests to several companies in the US, but did not get helpful information. The right parts seems not easy to get in any case ... Some info: > Original PT81 diff-housing No. 663473-4 > Original PT81 ratio 4.1:1 (pinion No. 663445 / ring No. 663446 ) > Preferred ratio 3.54:1 (does anybody know the Chrysler and/or Borg Warner part-No.`s?) > Alterantively 3.73:1 (does anybody know the Chrysler and/or Borg Warner part-No.`s?) Thank you much in advance ! Jan Quote
TodFitch Posted January 24, 2016 Report Posted January 24, 2016 Hey, my name is Jan and I am new here in that forum. I hope someone can help me regarding my questions: I would like to equip the differential of my 1939 Plymouth PT81 Pickup Truck with an other ring and pinion gear to reduce the rpm of the motor, but I am not quite sure which part No.`s fits to my differential. I have seen that this topic was discussed before, but I could not find closer information about the correct specification to my diff.. I am from Germany and information about Chrysler part No.`s of that time is not easy to get here (despite internet ...). I have sent requests to several companies in the US, but did not get helpful information. The right parts seems not easy to get in any case ... Some info: > Original PT81 diff-housing No. 663473-4 > Original PT81 ratio 4.1:1 (pinion No. 663445 / ring No. 663446 ) > Preferred ratio 3.54:1 (does anybody know the Chrysler and/or Borg Warner part-No.`s?) > Alterantively 3.73:1 (does anybody know the Chrysler and/or Borg Warner part-No.`s?) Thank you much in advance ! Jan According to the 1936-48 Plymouth parts manual for PT81: 3.73 Ratio uses: 1125140 - Differential and carrier assembly 1192393 - Drive gear and pinion matched set 671673 - Drive gear (41 teeth) 671674 - Drive pinion (11 teeth) 4.1 Ratio uses: 1121845 - Differential and carrier assembly 1192394 - Drive gear and pinion matched set 663445 - Drive gear (41 teeth) 663446 - Drive pinion (10 teeth) 4.3 Ratio uses: 864174 - Differential and carrier assembly 865690 - Drive gear and pinion matched set 663459 - Drive gear (43 teeth) 663460 - Drive pinion (10 teeth) 4.78 Ratio uses: 1141925 - Differential and carrier assembly 1192396 - Drive gear and pinion matched set 663647 - Drive gear (43 teeth) 663648 - Drive pinion (9 teeth) (I hope I transcribed all the correctly) 1 Quote
PT81Jan Posted January 24, 2016 Author Report Posted January 24, 2016 According to the 1936-48 Plymouth parts manual for PT81: 3.73 Ratio uses: 1125140 - Differential and carrier assembly 1192393 - Drive gear and pinion matched set 671673 - Drive gear (41 teeth) 671674 - Drive pinion (11 teeth) 4.1 Ratio uses: 1121845 - Differential and carrier assembly 1192394 - Drive gear and pinion matched set 663445 - Drive gear (41 teeth) 663446 - Drive pinion (10 teeth) 4.3 Ratio uses: 864174 - Differential and carrier assembly 865690 - Drive gear and pinion matched set 663459 - Drive gear (43 teeth) 663460 - Drive pinion (10 teeth) 4.78 Ratio uses: 1141925 - Differential and carrier assembly 1192396 - Drive gear and pinion matched set 663647 - Drive gear (43 teeth) 663648 - Drive pinion (9 teeth) (I hope I transcribed all the correctly) Wow, tank you much for that immediate info !!! Some time ago one guy wrote that early 50s Plymouth car ring&pinions might also fit to trucks (--> http://p15-d24.com/topic/28233-rear-end-ratios/ 3.54:1 seems also to exist. But I also would be happy to find the 3.73:1.... Is there a source where to get ring and pinions of the required ratio and type? (I know they seem not too easy to get ...) Thank you again ! Quote
Jeff Balazs Posted January 24, 2016 Report Posted January 24, 2016 Can't help you with any specifics but I have a 3.55 rear axle in my truck and it is IMO a bit too high for the truck. 3.73 would probably work better. Jeff 1 Quote
Young Ed Posted January 24, 2016 Report Posted January 24, 2016 I put a 3.90 in my 46 and I find with the tall 16" wheels that its quite sufficient. I don't think I'd go for more than 3.73. Quote
Frank Elder Posted January 25, 2016 Report Posted January 25, 2016 3.54 lacks Leistung to push your LKW. Quote
PT81Jan Posted January 25, 2016 Author Report Posted January 25, 2016 Thank you all for your tips and experiences ! Really interesting and helpful for me. @Jeff: What truck do you have - also a PT-truck ? Original transmission ? @Ed and Frank: I agree. I also feared that 3.54 could be too much of the good. To calculate the speed and rpm is only the half of the story ... By the way, I have the original 201 cu.in. engine, bored up to 218 cu.in. /aluminum pistons, original 3 speed transmission, 15" rims, 225/75R15 tires front and rear. If someone has a tip for me where to get the matching ring and pinion, it would be perfect ! (Hardly a chance to get here in Germany) Thank you again guys ! Jan Quote
Young Ed Posted January 26, 2016 Report Posted January 26, 2016 With the 15s you might get away with that 3.54 but I'd still go for that 3.73. I have 16s and a 3.90 and the truck goes as fast as I dare. Quote
PT81Jan Posted January 26, 2016 Author Report Posted January 26, 2016 I think I will try the 3.73 (1192393 - Drive gear and pinion matched set / 671673 - Drive gear (41 teeth) / 671674 - Drive pinion (11 teeth) if i find one ... Quote
Young Ed Posted January 26, 2016 Report Posted January 26, 2016 (edited) I think I will try the 3.73 (1192393 - Drive gear and pinion matched set / 671673 - Drive gear (41 teeth) / 671674 - Drive pinion (11 teeth) if i find one ... Look to the little later Plymouths-probably the other DPCD cars too. You will have to change the side gears most likely as the axle spline count changed. No big deal and then it will bolt right in. French lake auto parts has a whole row of 54 Plymouths that might have one. Edited January 26, 2016 by Young Ed Quote
Brent B3B Posted January 26, 2016 Report Posted January 26, 2016 I can't say for Plymouth to Plymouth but something to consider might be the side gears "cut" matching up. Sadly I can't report on performance but, my last years winter project was swapping the R&P on my B3B from 4.1 to 3.73 \ http://p15-d24.com/topic/37645-rear-end-swap-upgrade/page-12?hl=+rear +gears Quote
PT81Jan Posted January 26, 2016 Author Report Posted January 26, 2016 @ Ed J @Brent B3B: I do not completely understand why the side gears have to be changed, too. I have an idea, but I think I have to make deeper thoughts ... @ Ed J: Thank you for your tip with French lake auto parts -> their server did not connect, will try it tomorrow again. @Brent B3B: Thank you for the link ! Every kind of info helps ! Disassembling was not difficult, I needed less than an hour. No special tools required. Assembling will be the greater challenge ... More tips are likely to raise ! Quote
Young Ed Posted January 27, 2016 Report Posted January 27, 2016 (edited) @ Ed J @Brent B3B: I do not completely understand why the side gears have to be changed, too. I have an idea, but I think I have to make deeper thoughts ... @ Ed J: Thank you for your tip with French lake auto parts -> their server did not connect, will try it tomorrow again. @Brent B3B: Thank you for the link ! Every kind of info helps ! Disassembling was not difficult, I needed less than an hour. No special tools required. Assembling will be the greater challenge ... More tips are likely to raise ! After about 53 they changed the spline count of the axles. So if you have early axles and a late diff the axles won't go in. I had this issue with my 48 plymouth only I didn't find out until the diff was already in the housing. So we reused the original side gears so that the spline count wasn't an issue. Here you go some of the 53/54s at french lake Edited January 27, 2016 by Young Ed 1 Quote
PT81Jan Posted January 31, 2016 Author Report Posted January 31, 2016 Hello again, just one question again: Does anyone know the corresponding Borg Warner Part-No.`s of the 3.73 : 1 ? This possibly would help me to find the matching ring & pinion for my PT81. Chrysler Part-No.: (thanks again Tod !!!) 3.73 Ratio uses: 1192393 - Drive gear and pinion matched set 671673 - Drive gear (41 teeth) 671674 - Drive pinion (11 teeth)" Here the Borg Warner of the 4.1:1 and 3.9:1 - unfortunatelly did not find the 3.73:1 1 Quote
Jeff Balazs Posted January 31, 2016 Report Posted January 31, 2016 If you do not find what you are looking for the rear axle from a Jeep Cherokee is a pretty easy swap in. They are available in 3.73. 1 Quote
Plymouthy Adams Posted January 31, 2016 Report Posted January 31, 2016 Jeff Balazs, on 31 Jan 2016 - 1:27 PM, said:If you do not find what you are looking for the rear axle from a Jeep Cherokee is a pretty easy swap in. They are available in 3.73. as the man asking lives in Germany...I am not so sure what he may or may not be able to find locally in his wrecking yards...here in the states...swapping is a no brainer as they say... Quote
Jeff Balazs Posted January 31, 2016 Report Posted January 31, 2016 as the man asking lives in Germany...I am not so sure what he may or may not be able to find locally in his wrecking yards...here in the states...swapping is a no brainer as they say... Perhaps.......but might be easier to find than the gear set to fit the original housing.??? Quote
Plymouthy Adams Posted January 31, 2016 Report Posted January 31, 2016 yes Jeff...if buying gears only,,.,,postage and customs from US on them alone may well be the best bet ...I wish the man the best of luck given his location and limited resources for old car parts of the US origin Quote
Jeff Balazs Posted February 1, 2016 Report Posted February 1, 2016 Certainly that has to be a problem for anyone with one of these in Europe. I had heard that there were quite a few Cherokee's exported hence the suggestion. Maybe that is not the case? Just an idea anyway. Quote
Plymouthy Adams Posted February 1, 2016 Report Posted February 1, 2016 I know the Cherokee was popular in Europe and with the Daimler ownership at one time could have even boosted sales over and above...as they are most likely available at time to time in wrecking yards...the next question is at what cost...and what is the competition in securing these parts...could well be a waiting list...many English cars use Dana 44 based rear axles...Salisbury trade name....even into the late 70's these axle are still taper shaft, keyed and nutted...axles are available...often to the tune of changing the wheel bolt patterns..I have 6 Salisbury axles here at the house in various sport cars..stock and a few are posi tracs Quote
Jeff Balazs Posted February 1, 2016 Report Posted February 1, 2016 I was thinking more along the lines of a Dana 35 which is found in a lot of 2wd Cherokee's. I believe 3.73 ratio was a pretty common set up. Doesn't do you any good though if it is harder to find than a set of stock ring and pinion gears. And you would need to verify the width for the specific truck you have. Again just an idea for an alternative fix. Jeff Quote
Young Ed Posted February 1, 2016 Report Posted February 1, 2016 I was thinking more along the lines of a Dana 35 which is found in a lot of 2wd Cherokee's. I believe 3.73 ratio was a pretty common set up. Doesn't do you any good though if it is harder to find than a set of stock ring and pinion gears. And you would need to verify the width for the specific truck you have. Again just an idea for an alternative fix. Jeff Can't verify how he'll find it but I believe it would be a good fit. I've got a jeep rear end for my project 47 and it was very close to the original width. Off the top of my head I believe 1inch shorter. Quote
PT81Jan Posted February 1, 2016 Author Report Posted February 1, 2016 Ed and Jeff: Nice to read your conversation about my problem: > I don`t know even one junkyard here in Germany that has vehicles that are older lets say 30 years . Not to think about to find US cars and parts of the 30s ...60s on a junkyard. > But, of course there are several companies that have been specialized in US cars of that time. Something like "my" ring & pinion is to specific. If you have great luck you`ll get something like that. If not, you have to expand your search around the globe ... > Since my PT81 has got an axle which is in very good condition (and I had previously modified to lower the truck some inches), the best solution seemed to swap the ring & pinion. If I don`t find one, I indeed have to go to plan B and will looking for an alternative axle. My thoughts were searching one of a later truck, Mustang or Corvette which are more common here. Thanks for the cherokee hint, could really be a solution for me ! There should be parts around, too. But as mentioned the preferred solution would be to find the matching parts - hope dies last 1 Quote
Jeff Balazs Posted February 1, 2016 Report Posted February 1, 2016 My luck ....or lack of it......is the reasoning behind the Cherokee axle suggestion. You might get lucky and find what you are looking for. Being in the right place at the right time helps. It also depends on how long you might want to or be able to wait for the correct parts. Jeff Quote
PT81Jan Posted February 1, 2016 Author Report Posted February 1, 2016 Jeff, I had to seal an oil leak at the axle, so I decided to do some improvement at the same time. I still have my good 4.1, so I am able to drive. Will look forward to be in the right place at the right time ! But I will look out for an achsle which could fit, too. Thanks again for all the tips ! Quote
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