Power Steering Belt too short?

[Alger R.]

on my 75, the reproduction (Date Coded) P.S. Belt from Quantem when installed, will not allow enough outboard adjustment of the P.S.Pump to allow the Pump Cap to be removed. (It interferes with the Alternator Bracket). The measurement of the belt is correct at 36 inches but the width seems to be on the high side. This may not allow the belt to sit deep enough. When I put the old 36 inch original on, it fits and allows enough Pump adjustment for the cap to clear the alternator bracket and be removed. I tried a second Belt from Quantem with no improvement.

Has anyone encountered the same problem?

[Martin N.]

Re: Power Steering Belt too short?

on my 75, the reproduction (Date Coded) P.S. Belt from Quantem when installed, will not allow enough outboard adjustment of the P.S.Pump to allow the Pump Cap to be removed. (It interferes with the Alternator Bracket). The measurement of the belt is correct at 36 inches but the width seems to be on the high side. This may not allow the belt to sit deep enough. When I put the old 36 inch original on, it fits and allows enough Pump adjustment for the cap to clear the alternator bracket and be removed. I tried a second Belt from Quantem with no improvement.

Has anyone encountered the same problem?

Same problem on my 74 L-48 this past Feb. I called Quantem and they told me the belt was labeled wrong from their supplier and that they would send out the correct width, which they did approx. 2 months later, fit like a champ. I'd call them and let them know, hopefully the'll be as responsive to you as they were to me.

I don't remember, nor did I write down the belt length though. I wouldn't believe that there would be a difference between the 2 years. Keep us posted.

Marty

[Joe L.]

Re: Power Steering Belt too short?

Same problem on my 74 L-48 this past Feb. I called Quantem and they told me the belt was labeled wrong from their supplier and that they would send out the correct width, which they did approx. 2 months later, fit like a champ. I'd call them and let them know, hopefully the'll be as responsive to you as they were to me.

I don't remember, nor did I write down the belt length though. I wouldn't believe that there would be a difference between the 2 years. Keep us posted.

Marty

Marty and Alger-----


Actually, there was a difference between 1974 and 1975. Here's why: 1974 was the last year for the use of the tapered shaft power steering pumps and pullies. For 1975, the pumps for most Chevrolet applications, including Corvette, were changed to the non-tapered shaft with press-on type pullies. Presumably, this change was done so that the pullies could be pressed on the shaft at different spacings to accommodate a wide range of applications. In any event, the 63-74 pullies are different than the 75-82 pullies.

If the power steering pump pullies had been kept the same OD, the above would have resulted in no difference between the belts used for 1974 versus later. However, that's not what happened. The "corollary", stamped steel pullies for 63-74, GM #3770509, and 75-82, GM #346289, were of slightly different OD. The difference was only 1/64", but that's enough to make a slight difference in belt OD for a situation in which belt length is critical for component positioning (as is the case here).

The 1974 belt was supposed to be 36-1/4" OL; the 1975+ belt was supposed to be 36" OL. Both belts were 3/8" width which is somewhat unusual since most 73 and later belts were 7/16" wide.

[Martin N.]

Re: Power Steering Belt too short?

Marty and Alger-----


Actually, there was a difference between 1974 and 1975. Here's why: 1974 was the last year for the use of the tapered shaft power steering pumps and pullies. For 1975, the pumps for most Chevrolet applications, including Corvette, were changed to the non-tapered shaft with press-on type pullies. Presumably, this change was done so that the pullies could be pressed on the shaft at different spacings to accommodate a wide range of applications. In any event, the 63-74 pullies are different than the 75-82 pullies.

If the power steering pump pullies had been kept the same OD, the above would have resulted in no difference between the belts used for 1974 versus later. However, that's not what happened. The "corollary", stamped steel pullies for 63-74, GM #3770509, and 75-82, GM #346289, were of slightly different OD. The difference was only 1/64", but that's enough to make a slight difference in belt OD for a situation in which belt length is critical for component positioning (as is the case here).

The 1974 belt was supposed to be 36-1/4" OL; the 1975+ belt was supposed to be 36" OL. Both belts were 3/8" width which is somewhat unusual since most 73 and later belts were 7/16" wide.

JOE-

Heads on as usual with your information. My P/S pump pulley is stamped 3770509. Perhaps Alger should start with checking (if he can) his P/S pulley # and going from there.

ALGER- My belt # from Quanta for the P/S Pump was B-234D

Marty

[Alger R.]

Re: Power Steering Belt too short?

Marty & Joe,

Thanks for the info. My Pulley is the correct 346289 and is pressed onto the pump shaft. The belt measures exactly 36 inches but it wouldn't suprize me if the width was 7/16 and not the correct 3/8. I will verify tomorrow. If the 75 Belt for whatever reason does not fit, I may have to get the 74 at 36 1/4 and live with the date code discrepency. (Not something I want to do because I have the NCRS Disease and can't accept anything but what is correct for the car).

JOE-

Heads on as usual with your information. My P/S pump pulley is stamped 3770509. Perhaps Alger should start with checking (if he can) his P/S pulley # and going from there.

ALGER- My belt # from Quanta for the P/S Pump was B-234D

Marty

[Jim S.]

Re: Power Steering Belt too short?

The single biggest reason for the change from the tapered driveshaft and keyed pulley to the interfernce fit pulley was to reduce warranty claims. The interference fit pulley design virtually eliminated loose pulleys caused by improperly torqued nuts at the assembly plants. I don't know why, but that was a year in and year out problem in the GM car assembly plants. All GM power steering pumps were changed to the interference design for 1975 start of production.

The AIM sheets indicate the face of the pulley hub to be pressed flush to the end of the driveshaft (+/- 0.010 inch). The pulley was to be designed so that the groove would be located within the following area: from the face of the outboard front mounting pads forward 1.56 inches (almost to the face of the driveshaft seal.) This was to insure that bushing inside of the pump that supported the driveshaft would have good durability.

The assembly plant was not not supposed to adjust the pulley press to vary the location of the pulley groove.

Jim