[tooski]

The 1310 u joint thread got me thinking about the u joints in my '75. I didn't want to jack that thread. The 3R size is in between the 1330 and 1350 .

[grivera]

Interestingly I learned today my front joint is 1310 and rear is 3R- and not 1310 as originally thought. Looking forward to comments on this thread.

[78w72]

Originally Posted by grivera

Interestingly I learned today my front joint is 1310 and rear is 3R- and not 1310 as originally thought. Looking forward to comments on this thread.

as you noticed before, youre going to get all kinds of opinions on this, which is the norm for almost any topic on forums. one person will insist they are only good for a 6cyl & worthless for anything above 300hp... the next person will say they are ok for 400-500hp.

i try to refrain from absolutes or arguments like that or claiming how strong a certain factory part is without real world controlled testing. i just give my personal experiences or state what others i know of have experienced. one guy can pretzel a stock driveshaft behind a 2 barrel 300hp engine & others have gotten by with stock ones close to or at 500hp. every case is different with things like this.

my "guess" is a 3R or 1330 solid u joint is ok for the average mild built pontiac street car that doesnt see racing or heavy abuse. mild & street car to me is about 400-425 or less hp, on street tires doing some burnouts & occasional heavy throttle short runs on the street where the engine rarely hits max rpm or power, & even the rare test & tune with radials & crappy track prep in the low 13s to 12's. beyond that its best to have a stronger d/s, yoke & u-joint.

[78w72]

Originally Posted by tooski

The 1310 u joint thread got me thinking about the u joints in my '75. I didn't want to jack that thread. The 3R size is in between the 1330 and 1350 .

what engine/trans did your 75 come with? i have a 72 firebird that had a 350/350 & im not 100% sure what rear u joint it has off the top of my head, i did buy new solid joits for it but would have to check my receipts.

i always thought these cars used a 1310 or 1330. wasnt aware of the 3r being between 1330 & 1350, that sounds like a good middle ground size for most street cars.

['ol Pinion head]

3R u-joints are plenty strong enough for all but one of my keepers & projects. Have built too many rears for low to high 11 sec cars that both, have held up year after year with 3R pinion flanges & either oem or budget local driveshaft shop driveshafts. At that performance level, the longer the driveshaft that's often been when an upgraded chrome moly shaft has been sourced. Not often the case with 48 & 49" long driveshafts.

3R u-joints are not bigger than Spicer 1330's. They are identical in size, the way the bearing caps are retained is the difference between the two styles. OEM 3R's the caps are retained to the u-joint with injected plastic. Replacement 3R's use a thick wire type c-clip. The Spicer 1330's use a circular type clip on the external end of the cap.

[Skip Fix]

Good enough for 1.51 60 fts with slicks in a 3750 lb car! I did use the Lakewood solid U joints in the stock driveshaft and have it balanced better than stock.

['ol Pinion head]

Originally Posted by 78w72

what engine/trans did your 75 come with? i have a 72 firebird that had a 350/350 & im not 100% sure what rear u joint it has off the top of my head, i did buy new solid joits for it but would have to check my receipts.

i always thought these cars used a 1310 or 1330. wasnt aware of the 3r being between 1330 & 1350, that sounds like a good middle ground size for most street cars.

The original driveshafts in all 75-81 F-body's all came with 3R ujoints. It was never a what engines up front type of deal. A few '71 3.42 posi T400 T/A/ Formula rears came OEM with 3R pinion flange & matching driveshaft. Most came with Spicer 1310's. Both my 4peed '72 & 73 T/A's came with Spicer 1310 pinion flanges, yokes, & driveshafts. '74 models were the last model F-body, X-body, & A-body (c-clip axle Chevy built 8.5) rears that GM used the "small Chevy" 1310 pinion flange. Years ago in the Pick-n-Pulls I used to pull the Spicer 1310 pinion flanges off the '73 & 74 Monte & Malibu rears. Was often out of that style of pinion flange & needed them for budget built 8.5 X-body posi rears for the Chevy guys.

[78w72]

Originally Posted by 'ol Pinion head

The original driveshafts in all 75-81 F-body's all came with 3R ujoints. It was never a what engines up front type of deal. A few '71 3.42 posi T400 T/A/ Formula rears came OEM with 3R pinion flange & matching driveshaft. Most came with Spicer 1310's. Both my 4peed '72 & 73 T/A's came with Spicer 1310 pinion flanges, yokes, & driveshafts. '74 models were the last model F-body, X-body, & A-body (c-clip axle Chevy built 8.5) rears that GM used the "small Chevy" 1310 pinion flange. Years ago in the Pick-n-Pulls I used to pull the Spicer 1310 pinion flanges off the '73 & 74 Monte & Malibu rears. Was often out of that style of pinion flange & needed them for budget built 8.5 X-body posi rears for the Chevy guys.

thanks for the info, wasnt sure if the years changed rear yokes/u-jpimts.

i thought different engines determined the yoke/ujoint sizes mainly because when i had a 78 t/a back in the late 80's through mid 90's that had a 74 455 & th400 driveshaft in it, i pulled a 8.5" rear from a late 70's base model camaro in a junkyard for a gear change & i had to use a conversion u joint with it. cant recall the specifics but was pretty sure the rear yoke on that was different than the end the th400 d/s had from a 74 firebird. i could be wrong but almost positive it needed a conversion joint.

['ol Pinion head]

With the '74 T/A driveshaft it would have smaller 1310 u-joints & make a necessity of the adaptor u-joint to mate with a late 70's Camaro rear.

Went through a similar situation in the mid 80's when I installed a '70 PQ T400 in my '80 turbo car. While local boneyarding, pulled the factory driveshaft & 12 bolt out of a '70 Formula. Upon getting home, decided it was just as eay to have a '73 GP driveshaft i had shortened @ local shop. $22.50 to shorten, $25 to balance...miss those days & Agnew Machine, hauled a ton of factory driveshafts down there through the 90's to be cut down 7/8" for 8.2 to 8.5 A-body & X-body rear swaps.

[tooski]

Yup, my car came with a 350/350 with the 3R u joints. I upgraded to a RA III 400 with an HC-02 cam, stock TH400. Same 3R joints. Only had street tires that did not hook, so not a lot of stress incurred. My 3R's have the inside clips. I believe I changed them when I changed the trans slip yoke.

1350 3 5/8 overall length (outside locks) 1 3/16 dia caps
1330 " " 1 1/16 caps
3RL 2.556 lock to lock (inside) about 3 5/8 overall length. 1 1/8 caps

So, I believe the 3R are better than a 1330, not as good as a 1350.

http://www.driveshaftspecialist.com/...D%20Guide.html For U joint ID's

From Denny's site.
" 3R series
2.556 inches wide between the yoke inner surfaces where the "C" Clips lock in. Original equipment universal joints were held in place by injected plastic...replacement universal joints will have "C" Clips to hold joint into yoke. Approximate overall width cap to cap is 3 5/8 inches
2 bearing caps are 1.125 inch (1 1/8) diameter "