British KV-1 and T-34

[marathag]

I dont think you can be ideal, with hindsight It's easy to improve almost anything, for example using a lower drive shaft (like later TDs) on M4 to drop the hull height and adding the later modifications earlier would all make it better?

That's the problem with the M4, it had potential to be better, but wasn't done, a victim of it's success in the Desert in 1942, and Armor Board Dawdling

PostWar Israeli example of close to ideal Sherman, the Degem Yud prototype
Cut down hull with lower driveshaft, wider suspension that was developed from the M6 Heavy Tank and turret fitted with a counterweight
to balance a more powerful gun that had its mount moved forward on the original 'small' 75mm turret to allow a more powerful French L61 CN 75-50 gun(with attending increased recoil) to be fitted, with a more powerful diesel engine

Ex-Croatian M-36 fitted with Soviet V-2 Diesel

with the longer M4A4 Sherman hull, the extension box would not been needed.
In 1942, the US could have used the Hall-Scott V12, or go with the original Ford V-12 design before it was cut down to a V-8

 

[mial42]

Don't think it would work well. A lot of the T-34's design compromises wrt maintenance/reliability/quality didn't matter much on the Eastern Front: when your life expectancy in combat can be measured in weeks and you're losing tens of thousands of tanks a year, being able to drive hundreds of miles or be easily repaired just doesn't matter much. The British were facing a very different war.

 

[fastmongrel]

I dont think you can be ideal, with hindsight It's easy to improve almost anything, for example using a lower drive shaft (like later TDs) on M4 to drop the hull height and adding the later modifications earlier would all make it better?

Better is always the enemy of good enough. You don't get all the M4 Sherman or T34 chassis by stopping to change for something better. That's what the Germans did and I am not sure how many PzIIIs and PzIVs they could have built without messing about with Panthers and Tigers and associated chassis

 

[jsb]

Better is always the enemy of good enough. You don't get all the M4 Sherman or T34 chassis by stopping to change for something better.

Yes, but they did change along the way as they produced them, 76mm, HVSS, changing hatches and front castings etc...
I dont think a drop in high could not have been fitted in as another modification and so long as they do it in stages using mostly the same parts it should not hit production numbers much or reliability?

 

[marathag]

Yes, but they did change along the way as they produced them, 76mm, HVSS, changing hatches and front castings etc...

More so that both nations had multiple factories making the types, where retooling a single factory wouldn't have effected overall production that much.
As it was, most of the Railroad Builders had lost most of their Tank contracts in 1943. Of the almost 89,000 AFVs built, here is the breakdown

Pullman-Standard 3,926
American Locomotive Works 2,985
Baldwin Locomotive Works 2,515
Lima Locomotive 1,655
Montreal Locomotive Works 1,144
Pacific Car and Foundry 926
International Harvester, Burlington 7

Now the last was set to mass produce Light and then Medium tanks, but only built a handful of M7 before that program was spiked, so its Armor Casting Foundry went pretty much unused during the War
Any of those could have been converted to build the T20 or Improved Shermans or even a Heavy Tank or more Jumbos without effecting the overall production needed being under 15% of total production

 

[Driftless]

That's the problem with the M4, it had potential to be better, but wasn't done, a victim of it's success in the Desert in 1942, and Armor Board Dawdling
View attachment 700358
PostWar Israeli example of close to ideal Sherman, the Degem Yud prototype
Cut down hull with lower driveshaft, wider suspension that was developed from the M6 Heavy Tank and turret fitted with a counterweight
to balance a more powerful gun that had its mount moved forward on the original 'small' 75mm turret to allow a more powerful French L61 CN 75-50 gun(with attending increased recoil) to be fitted, with a more powerful diesel engine

There's a candidate for Claymore's workbench....

 

[Bougnas]

Yes, but they did change along the way as they produced them, 76mm, HVSS, changing hatches and front castings etc...
I dont think a drop in high could not have been fitted in as another modification and so long as they do it in stages using mostly the same parts it should not hit production numbers much or reliability?

The M5 Stuart and large hatch wet 76 Shermans were very extensive modifications of their predecessors, so I don't see any problem with cramming more improvements in the Sherman. The transfer case was already developped for other vehicles and was not a particularly tricky part, and was only necessary with the radial and the Multibank IIRC. Considering that the Ford-powered M4A3 became the primary US Army tank in the second half of the war, one could even ignore the transfer case altogether and only redesign the future production M4A2s and A3s. However, it seems the US expected the T2X program to succeed early on, which may have reduced the motivation to develop an improved Sherman.

Increasing standardization with the M10 GMC hull was probably feasible. It already featured the reduced height when using the low-driveshaft engines without a transfer case, for both the GM 6046 and Ford V8. I don't think a transfer case would have particularly improved things here. Further reductions in height would require having a raised engine deck or the T2X's Ford GAN which was a reduced height version of the GAA. However it had teething troubles in the T2X so not sure it could be made reliable in time.
In any case, this was proposed by Detroit in 1942 so hardly a new thing.

The reduction in height and the need to redesign the front with large hatches and less weakpoints could also allow the use of the M10's front slope of 55° with the large hatch hull thickness of 63mm without any increase in weight, increasing protection over a regular large hatch Sherman. Assuming this isn't too much work to redo the ergonomics of the driver and his assistant.
The turret basket and crew stations would have to be altered, but since some work on that was done to accomodate wet stowage, this isn't too difficult.

If there is still some weight budget left thanks to the height reduction, it could feature Detroit's proposed 30° sloped sponson sides, increasing the protected arc.

I also don't see why HVSS couldn't have been finished earlier. Some form of it was tested on the M6, T14 and proposed on M4X Sherman, and the US was developping new tracks at a rapid pace. Ditching the poor M6-type tracks in favor of OTL HVSS-type tracks early enough to see it in production on these more ambitious large hatch Shermans in late 1943 was probably feasible. That could allow a greater weight budget if some loss in power-to-weight ratio is acceptable, to improve front armor further. Under a ton should be enough to be highly resistant/immune to PaK 40 frontally.

This shows more or less what I mean when it comes to the height/hull front/sponson/ergonomic improvements.

 

[edgeworthy]

For the sake of completeness here is the US Engineering Analysis of the T-34/85 from the Korean War.
https://www.cia.gov/readingroom/docs/CIA-RDP81-01044R000100070001-4.pdf/

 

[jsb]

I would personally ditch the hull gunner (for ammo storage if sponsons are getting ever smaller) and maybe even go for a British rear drive design (US made lots of good automatic transmissions so should work) and a heavy low velocity thin walled HE shell (from Soviet thinking) to make it even better?

 

[Ramontxo]

As I understand it, the urban warfare battles of 1944 and 45 made both the Soviet and the US army bring back the frontal MG gunners. And some interesting multi machine gun addition to tanks (fixed and otherwise) were proposed to American tanks beacouse of it. I know that with hindsight everybody substituted the frontal machine gunner for room for ammunition and the like. I just doubt it would be so obvious in WW2