4 Speed Durability Behind LS (3 Viewers)

[Jackson Hanes]

I’m sure there are threads on this I just can’t find em.

I’m running a 5.3 infront of a stock h42 4 speed and t-case.

I have the motor out to do some upgrades and was thinking if I should upgrades the transmission.

Even driving it the 500 miles I’ve had some weird things going on the with trans and am questions it’s durability.

Should I just bite the bullet and re do all of my work?

 

[ferg]

I ran a 4spd behind an SBC for over 10 years. No trans problems at all. California deserts, mountains P4W Round Up, Sierra Trek, HDR etc.

Keeping drive shafts together was a whole other story.

 

[cruisermatt]

What sort of issues?

 

[pb4ugo]

Yrs ago, I've run stk and high hp sbc's and a 454 BBC with the stk 4 speed. I never had a problem with them. I Raced a lot along with hard trail riding. The weakest link was the one piece tcase. I've broken a number of them. The rear third member didn't like the 454 on the street.

 

[Jackson Hanes]

What sort of issues?

It has been making more noise going into gear recently.

also it refused to go into third a few times and left me in some awkward spots.

im not too familiar with these older manuals so i guess i dont know what is normal and what isnt.

 

[charliemeyer007]

Proper adjusted clutch is important. Synchronizer can were out with age or improper lube. Then there is how it was driven - much easier to to stress stuff out out when powering it with 2 to 4 times the power it was designed for.

 

[1911]

The H42 is pretty stout, much beefier gears than say mini truck or heep transmissions. If set up properly, they can take a lot of abuse.

 

[POPO AGIE]

How many miles are on the gear boxes? I rebuilt the 4speed and transfer case from my 78 that was behind a 2F and 155F so not near the hp or torque but overall everything looked good at 103K miles. The only wear I found was on the TC input gear and transmission output shaft which was normal for shifting gears with the torque being applied then backed off to shift.

 

[Living in the Past]

What transfer case? With a V8 would probably change it versus rebuilding it it's mated to a one piece transfer case. Orion or split case would be a different story. Know nothing about Orion other than having a issue of popping out of gear in the past. More support for split cases. Those also have options on gearing. Possible to gear the diffs for street highway and lower gears in transfer case for off road. All things to think able if your doing anything to the transmission.

 

[peesalot]

Jackson, it depends alot on driving style and use. IMO the 4 spd will hold up. The tcase maybe not. You should have the taller geared tcase as well which isnt ideal for low range crawling. The 4spd isnt too hard to rebuild. I'd call Georg at Valley Hybrids, he may have a 4spd ready to go and he sells case savers for the tcase which would be a good idea. Have you taken the inspection cover off and looked to see if the clutch fingers are completely off the throw out at rest ? Is the clutch disc free when depressed ?

 

[NCFJ]

If you choose to go with another trans staying manual I'd go with a Tremec 4050. It's a 5 speed. I've swapped and driven the Toyota 5 speed, NV4500 and the Tremec behind a 5.3, and 6.0L and the Tremec made the others look pale IMO. Not sure on adapter to the case you have but there are a couple adapters available to a split case. My favorite swap to drive to date was a 60/80 with 6.0L Tremec 4050 and a split case. Love driving that truck.

 

[Jackson Hanes]

What transfer case? With a V8 would probably change it versus rebuilding it it's mated to a one piece transfer case. Orion or split case would be a different story. Know nothing about Orion other than having a issue of popping out of gear in the past. More support for split cases. Those also have options on gearing. Possible to gear the diffs for street highway and lower gears in transfer case for off road. All things to think able if your doing anything to the transmission.

I’m just running the stock t-case from the ’76 driveline; I was thinking about upgrading the t-case, but I’m waiting for a big disaster before I spend that dough.

Jackson, it depends alot on driving style and use. IMO the 4 spd will hold up. The tcase maybe not. You should have the taller geared tcase as well which isnt ideal for low range crawling. The 4spd isnt too hard to rebuild. I'd call Georg at Valley Hybrids, he may have a 4spd ready to go and he sells case savers for the tcase which would be a good idea. Have you taken the inspection cover off and looked to see if the clutch fingers are completely off the throw out at rest ? Is the clutch disc free when depressed ?

I do drive it pretty hard; I have a pretty heavy foot.

The clutch is properly adjusted — I know that for a fact. If anything, I don’t think I would rebuild; I would probably upgrade to a transmission with overdrive.

And i have installed the t-case saver already.

The H42 is pretty stout, much beefier gears than say mini truck or heep transmissions. If set up properly, they can take a lot of abuse.

I’ve heard mixed opinions: some say it’s fragile, while others claim it can handle plenty of abuse. Time will tell, but for now, my plan is to keep running it until it fails.

 

[Augustiron]

Not going into gear at times sounds like you're already there....

Fwiw, I have a butter shifting fj60 H42 behind my 5.3, but with a split case on the back in a 75 FJ40.

 

[Living in the Past]

I’m just running the stock t-case from the ’76 driveline; I was thinking about upgrading the t-case, but I’m waiting for a big disaster before I spend that dough.


I do drive it pretty hard; I have a pretty heavy foot.

The clutch is properly adjusted — I know that for a fact. If anything, I don’t think I would rebuild; I would probably upgrade to a transmission with overdrive.

And i have installed the t-case saver already.



I’ve heard mixed opinions: some say it’s fragile, while others claim it can handle plenty of abuse. Time will tell, but for now, my plan is to keep running it until it fails.

Before you do anything I would do my homework on cost of adapters between transmissions and transfer cases. The one piece case is the weakest option. Seen your first drive clip. Wouldn't count on the case saver to hold up to hot rodding. Add the twin stick shifter for the transfer case. Depending on what route you go you could find upgrading to be very expensive. Any transmission other than Toyota transmission with either a ten spline or sixteen spline output shaft with bolt directly up to the one piece case. You want to upgrade your transfer case later an Orion is only one that wouldn't require an adapter. Cheapest option is to do everything at the same time.

Here is why I would think long and hard about keeping the one piece transfer case and paying for an adapter to the transfer case.

Got the FJ40 out for the first drive, very exiting stuff.

too bad its just a GIF the 6.0 sounds pretty good
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