How strong are 1310 U Joints?
 

My 69 Bird has 3.08 gears and 1310 U-joints with zerk grease fittings and stock drive shaft. I’d like to go to track using 26x8.5x15 drag radials. The car has frame connectors that are welded in the front and bolted in rear. The engine made 521/631 on engine dyno with headers and 950 HP. In chassis it has Sniper EFI and Long Branch manifolds through 2.5” exhaust. TH400 with 13” Continental converter.

Is this a disaster waiting to happen and I should wait to upgrade drive shaft and 1350 U-joints? Would a good compromise be upgrading to 1330 U-joints.
FWIW, I wouldn’t plan to do this every weekend but maybe a few times a year.

Lots of power, highway gears, slicks. Upgrade the driveshaft.

If you're going to upgrade, don't waste time, money, effort, or enthusiasm with 1330s. Go straight to 1350s.

Do I need the 1350s on both ends or just trans yoke?

Just put Lakewood u joints in it it should be fine.

Are you leaving off the trans brake or the foot brake?

You're having a new driveshaft made. Put them on both ends.

Don't forget to buy the new yoke for the differential.

Foot brake

Uncharted territory for me - when replacing yoke on differential, is it simply remove and replace or are there concerns with crush sleeve or other settings?

The problem with just replacing u joints is you still have old cast diff and transmission inputs. I snapped my transmission input..the u joints held up..also cracked the transmission case.
I was at about the same power as the OP with the same rearend ratio..guess where all the stress goes to???

Go 1350 and be done with it……do the yoke and rear flange …… last thing ya want is the driveshaft ripping the floor up.

Thank you - will research and upgrade

Thanks Chris.

Gotta research rear flange replacement to avoid upsetting preload on pinion.

best thing to do 1350, done, and one less thing to worry about down the line
wish that was the option i was able to do when i needed mine made

a NEW yoke on the diff = new crush sleeve and turning torque measurement.
Open rearend...clean...run a pattern take a pic. (for reference later) remove the differential use a needle type torque wrench to rotate the pinion gear around NOTE: reading. Then remove old flange and crush sleeve. INSTALL new sleeve and yoke. Keep tightening until you have the same rotational torque reading you did before. reassemble rear end, quick check on the pattern to make sure its NOT screwed up....drive on

1350's problem solved

on to the next weakest link...lol

Install a ds loop, I've seen it happen!

Thanks - wasn't intending to get that far into this at this point. Project will have to wait...

If you take the brake drums off you can get a decent measurement of currant rotating torque if you have the proper torque wrench to do so. Than just reset with new yoke and new nut etc...

Usually if your just doing pinion only used bearings are 6 to 15 in lbs, new bearings are 15-30 in lbs, plus about 10 added for the carrier preload.

I have a solid 1310 in my 67 with an 8.5 out of a Nova. Its honestly the one thing that hasnt been upgraded. Unless you consider the solid joint an upgrade.

I have solid 1350 in the front. Its just a PITA to change the differential yoke. Thats the only reason I havent upgraded it yet.

From what I understand the solid joint is a pretty big upgrade from the hollow joint. So if you wanted an in between, you could go to a solid joint.

If you just want to go to a simple track outing before things close out there, and have a little fun with the car, I'd run what ya got.
Being an automatic and a footbrake car you'll likely be just fine for a fun track day, I just wouldn't make a habit of it. Chances are the track won't have "radial" prep anyway, and if the suspension doesn't have some tricks you probably won't be cutting stellar 60 foot times anyway. Go have some fun. If you're already down for winter, then make the upgrade.

I've gone 11's in a pretty heavy car with 1310 joints and stock yokes, again in an automatic car and foot braking it. Never broke the shaft or anything related to it but I wasn't there every weekend pounding on the car either.
Funny, most of the stuff we've raced for years had stock driveshafts in them and never broke a driveshaft. Dad's GTO was running mid 11's since around 2000 with it's original 50 year old driveshaft and some greaseable u-joints in it, lol. Nice wheelies and 1.5 short times. Never broke. He has only recently went to a 1350 shaft good for 1000hp when he upgraded the engine. I did the same on my Chevelle when I swapped to a 4L80E, figured it was a good time to do it.

At some point you'll want to upgrade though. If for nothing else just piece of mind.

1350's with a stronger shaft make the most sense if you're going to spend the money and spend a lot of track time with the car. Upgraded yokes at the same time are part of that, and you'll never have to worry about it again.

Your question on 1330's, our local driveline shop builds a nice heavier steel shaft with 1330's and he gives it about a 600hp/tq rating. I run one of those in one of our street cars with a 5 speed in front of it. This particular car isn't at that power level, and even with the added stress of popping the clutch and horsing around with the car, I don't even worry about it.

Thank you. All I'm looking for are a few timeslips to see what it can do, definitely not a regular journey. Our season goes till about Nov 30th...

Really you can use street tires, not worry about your u joints and just look at the MPH on the top end.

I have slips with the drag radials and with hard tires. The times are dramatically different but the MPH is about the same. That really tells you the power you are making anyway.

ds
 

For sure use a driveshaft loop. Cheap insurance. Ask me how I know.:D

Funny story - just called a local driveline shop to discuss options. Owner says, "That isn't a lot of horsepower - 1310s won't break." He offered to make a thicker walled 3" driveshaft with "high quality" 1310s...

Well there ya go.

Along those same lines, 2 cars here that are (or were at the time) making around 600 hp/tq, and weighing 4000 lbs. (one weighed 4108 with me in it) both ran mid 11's with the stock "original" shafts and greaseable u-joints in both cars for years.

You can figure your bird is quite a bit lighter than that, and a lighter car is certainly easier on parts.

Just to add, what I've seen break more often than u-joints are the cast yokes.

Our cars are very similar, and I have like 30 passes on my solid Spicer 1310. Probably 12 of them on sticky tires. So I agree. Like I said earlier, I want to upgrade mine for peace of mind, but probably wont bother until I put a little more gear in and have to break open the diff anyway.

Because of the similarity, Ill also be curious what you run. I just converted to a Terminator but with the Q Jet I ran a best of 12.2 with a 1.7 60'. You have a little more cam, I have a little bit more head and converter.

I thought about this but the Cooper Cobra radials are a bit hard and loose - they scare the crap out of me when I nail it at 50 mph...

My main concern is tghe 52 yo driveshaft and the 3.08 gears adding to the stress

Good to knw. Is yours a stock older driveshaft? What heads and cam?

Mine is a 3 inch shaft I had made. I bought my car as a basketcase so it didnt have anything as bourgeoise as a driveshaft included :D

It has 1350 joints in the front with a forged slip yoke, but a solid 1310 in the back to match the factory pinion on the nova 8.5 rear end. I originally was going to have the driveshaft guy put a 1350 conversion joint to the 1310 on the back, but he talked me out of it. Said the solid 1310 would be stronger than the conversion joint.

I also have 3.08s, but in an upgraded 30 spline differential. Heads are older bathtub style E heads with a little work. I think they flowed 303 cfm. Cam is a custom roller. Duration is similar to yours, in fact it might be identical, but yours has more lift. RPM intake with a little port work done to match 300 cfm heads.

Im thinking of going to 3.42s this winter so when I do that I probably also upgrade the pinion yoke to a forged 1350 unit.

FWIW Ive done a ton of laps on basically the same thing as the Cobras. Its fine. Even with normal tires the track is stickier than the road. I like the street tire class racing, just less likely to break stuff.

Great info - thanks

If you do end up going to 1350 joints at some point, just get a new shaft made. Getting ends put on is kinda pricey for what it is anyway. I think I paid $100 to get mine shortened when I swapped to the 8.5. A whole brand new one at a larger diameter is only like $300.

I don't think I mentioned it, but both of those cars I mentioned earlier have both been running their original 50+ year old driveshafts at those weights and going mid 11's. Both cars were raced 2-3 times a year for the last 30+ years.


Both of them have only just recently been upgraded to a larger driveshaft with 1350 joints.

Just to add for conversation,,,

I've had a few shafts made at our local driveline shop, and they have all been steel. He uses a thicker wall seamless tube.

When I did the 600hp shaft with 1330 joints for our daily driver, it's 3" diameter tube. I have to say, even that one was substantially heavier than the original stock shaft I pulled out. Really makes you think about how wimpy the stock shafts can be, yet the abuse they have taken in the other cars......

When we had a steel shaft made for dad's car, he wanted the 1350 version, and that one rated at 1000hp ended up being 4" in diameter. That thing is friggin heavy. Trying to wrap your hands around it and get it in the car, geeeez lol.

I did an aluminum 1350 shaft in my other car thanks to Dave hooking me up. It's 4" diameter yet felt like a feather, even compared to the original stock shaft I pulled out. I liked the unsprung weight idea simply because I run 4.10's in that particular car, and with the 4L80E that shaft is now spinning pretty good at 70 mph just cruising. 118-ish in the traps is also buzzing it pretty good, and I put the stock shaft through that for years, lol.

Just something worth considering.

Driveshaft diameter depends on length as much as it does torque load. And the material it's made from, of course.

The longer the shaft, the bigger around it needs to be. VERY bad things happen when the diameter isn't big enough, and the speed (RPM of the shaft) gets critical. It's a great way to find out if you mounted your driveshaft loop securely enough.

I ran my RAIV car for 15 years with a stick drive shaft abd lakewood joints.

I still have the original drive shaft w factory joints as well
So clearly Stephens didn’t break them. This is a stick car and while it had always been on fairly narrow slicks when steohens had it it 7 inch slicks. I ran it w 9 inch slicks w high ROM launches and it was fine.

Now that same drive shaft I raced it with w the Lakewood’s is in my turbo car running 9s and surviving.
The stock drive shaft is back in the RAIV car temporarily until I find another to put Lakewood’s in.

My Strange 3" Chromemoly shaft with solid 1350 joints was only about 300 at the time, very reasonable, plus I used their ends for trans and rear end, under a 100 a piece . A local shop is a dealer so didnt have to pay shipping. Very good piece of mind and a nice product

I would agree the strange stuff is good but I’ve seen a lot of guys break driveshafts that had good stuff . Why mine survived? Who knows. . Maybe because I air down my slicks enough so they can wrap up and take some of the HIt out. Really hard to say.

Many aftermarket driveshafts are more about being lighter than stronger.
Again can’t say what the reason is but can say that I’ve seen stock driveshafts live a long time and seen some
Good aftermarket ones beat up some floor pans .

Maybe people don’t use loctite and the u joints get wobbly, maybe they stressed them
Somehow when they were out of the car, a dent or a stress riser of some kind who knows why one survived and one doesn’t but I’ve seen both types fail

Had a similar debate w a friend
About n case 8.2 10 bolts Vs corporate 8.5s last week and why rear diff blow up. Whole can of worms there.

The driveline shop I called that suggested the 1310s said the 3” driveshaft with 1310s would cost $375!!

Ask them how much for 1350s.

That's in the ball park. Usually when I'm doing a stock shaft for a trans swap our local shop builds a new shaft with joints for about $300-$350-ish. Nothing extreme.

When I had the 1330 shaft done for 600hp/tq in 3" steel, it was around $450. And when he does a steel 1350 shaft for 1000hp it's right at $600.

On a side note, I had the 4" aluminum shaft done with 1350 joints, believe they rated that one at 1000hp, and it was also $600

Thanks for insight

i agree with roctimus & FJ that you should be fine for just a few test & tunes to see what the car will do. you said you have drag radials, not slicks as someone said earlier... with foot braking an auto & average track prep a stock driveshaft or u-joints in good shape shouldnt break . but the weak link is probably the u-joints. for peace of mind you can upgrade to solid joints, i used moog "super strong" brand solid joints on my stock yoke shaft & have done at least 15 low 11 sec runs & probably 20 other mid to high 11sec trying to get the best time, i have M/T drag radials with an auto & foot break it. car will do 119-123mph with a 500+hp 467 stroker.

history on my driveshaft is its a stock unit from a 1974 t/a that was behind a mild 455 in my t/a i had back in the 90's that was beaten & abused daily & nightly for about 10 years & close to or over 100k miles. that car died but i saved the 455 & driveline parts for a future build.... 10+15 years later i finally got around to doing another car to use it & went with the current stroker engine i have & reused the driveshaft but had a local shop make a new 3" shaft & reuse the yokes with solid ujoints, & have been racing & abusing that car for 5+ years now, so the yokes have almost 50 years of abuse behind a torquey 455 & lots of time behind a ~600lb/ft 467 with a lot of low 11 sec runs.

however, i realize ive pushed it far enough & am planning to buy a strange D/S with 1350 front yoke before trying to go an faster or break into the 10's. i am debating on doing the rear 1350 for the same reason as roctimus because changing the pinion is a PITA from what ive read, & the chances of a rear pinion yoke breaking at this power level with an auto & radials is pretty low... & if it does break at least its at the rear of the car & not as much of a safety concern as the front. im hoping a good solid rear joint will be enough for a mostly street car & limited track use.

Thanks for the real life example! I haven't actually ordered the tires yet but they are in my shopping cart! Mickey Thompson ET Street S/S, P235/60-15 to go on my spare 15x7 Rally IIs. Tread width is 8.31 as I'm limited in space with the 69 Bird quarter panel wheel well shape and the 8.5 is from a second gen so slightly wider than the factory 8.2 rear.

Quick question regarding my frame connectors. They are the bolt-in Competition Engineering square tubing type. Mine are welded in to the front subframe and bolted in in the front of rear leaf spring pocket. Any idea what power level these bolt-in types are good for? In other words, should they be welded in at rear for my power level (521 hp/631 tq engine dyno). This will be on Mickey Thompson ET Street S/S, 235/60-15.

i have kind of the opposite of you, my PTFB connectors are welded at the rear frame rail & bolted to the front subframe, i did this in case i ever need to remove the front subframe. i will let others comment on the power level they are good to, but IMO subframe connectors arent really rated for power, they strengthen the car/frame no matter the power level... but at some point racers do weld them at the front & rear.

it comes down to how much of a race car you intend this to be, sounds like its mostly a street car & i dont think youd see any real benefit welding them at the rear too. plus it will be a hassle to ever remove the subframe for you or the next owner. with drag radials & limited track time its probably not worth it, they are doing their job as is but again all depends on how much you plan to race the car.

Thanks - I prefer to have them bolt in but want to make sure they provide adequate protection from twisting.

IMO, 50 year old driveshafts are worthless, and I would never put anything with even OE power levels of the day in front of them. They were borderline when new.

If you're getting a new shaft made, upgrade to 1350s, period. What's the saying about the weakest link again? Yeah.

If the slip yoke is OE or old/unknown origin, it should be replaced regardless of power level.

Same on diff, if pinion yoke is OE, or of unknown origin, replace.

The new yoke MIGHT be slightly different than the one coming out, so, you MIGHT have to crush the sleeve slightly more. You can replace the pinion yoke and not have to setup the gears again if you are careful, and know what you're doing. Crushing a sleeve that's already been crushed is not easy, and it may weaken it, but you really don't know if you will have to until you try and check preload.

If the rear has a lot of miles on it, take the dive. If it goes away faster than it would have if you left it alone, it won't be by much of a margin.

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worthless? borderline when new?? i dont know about all that... for OE power, OE driveshafts in good shape are perfectly fine.

i think the track record of my OE shaft i posted above speaks for itself. & back in the day 99% of these cars used a stock shaft on mild built engines with a lot more power than stock & rarely ever broke. i had lots of friends back in the 80s & 90's with non stock cars of all makes that used stock shafts & nobody ever broke a yoke or shaft on the street or light duty racing with radials.

im sure there are some that had issues but its rare at best & calling a early to mid 70's TH400 OE yoke/shaft "borderline" for stock'ish cars making all of 200-350hp is a stretch.

i fully agree that the higher HP cars are making today should have a better shaft/yoke, but for a street car on hard street radial tires, the tires will break free before enough stress is created to break a shaft/yoke in good condition 99+% of the time.

Friend of mine had a '68 Chrysler Newport as his "high-school" car. 383 2bbl. The car would have been ten years old or newer. The thing had enormous torque--power-braking would scare people in the next lane over, it was like the car was going to lift up one side and tip over.

Wound the driveshaft up like a pretzel leaving a stop sign. Car coasted to a stop on the other side of the intersection. I won't promise the car had radials. Might have been mostly-worn-out stock-size bias ply tires on stock wheels..

Quick trip to one of the local Treasure Yards netted him a bigger-diameter shaft from a full-size Chrysler with a 440 as original equipment. Fit like it was meant to.

strong is better-always.
 

Had my stock steel driveshaft changed to 1350's and a forged sonnax yoke.

$325 driveshaft/$120 yoke money well spent.

I have a moser 12 bolt with the 1350 yoke as well.

I used the global west weld to the rear subframe, bolt to the front.

don't look under your car and have to ask, where's the beef!

Always amazed at the varied opinions on this forum…One thing of note is I’ve owned the car 27 years and the original 400 was tired when I acquired it so not sure what level of abuse the factory driveshaft endured…

great story, i had friends in HS with cars & stories like that or their parents cars they borrowed & beat the crap out of.

i dont doubt driveshafts, yokes or u-joints can & do break. strange that mopar 2 barrel would do that but im not familiar with how theirs were made or if the 2 barrel versions were weaker than the bigger engine stuff... or the history, coulda been exposed to major shock or misalignment or whatever to twist the actual shaft like that.

just saying its not at all normal for that to happen in a street car, aside from some very uncommon stories like that where it happened to someone you know or maybe even yourself 1 time back 20-50 years ago on an unknown condition part. depending on the car & its purpose, a good condition OE d/s should be fine with some good solid u-joints.

If you put any sticky tire on the car I would just get a new driveshaft with 1350 joints, a forged input and replace the yoke on the rear to a forged and never be concerned about breakage. Go on youtube and watch what happens when a driveshaft breaks going over 100 mph. It's one place you don't want to scrimp on.

If you choose to have a shaft made, the majority of the cost is labor and ends, it makes sense to just have a whole new shaft made. With u-joints, ends, and a slip yoke, expect to pay in the $350-$500 range.

After spending $15k-$25k on an engine/trans/rear, a simple $500 is a drop in the bucket for the piece of mind.

If you can't find a place local, Inland Empire, Dutchman, Denny's, Driveshaft Shop, all have very fast turn-arounds.

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If you're going to 1350 U joints why would you not step up to a 3 1/2 tube? Rhetorical question...

It seems to me going to 1350's, a 3" tube is now the new weak spot. JMO