Hotchis leaf sping pads. Use them or not? - Team Camaro Tech
Brakes, Suspension & Steering Conversion questions, Steering & Handling

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post #1 of 21 (permalink) Old Jan 18th, 02, 04:06 PM Thread Starter
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I'm putting Hotchkis rear springs in my car, and I'm wondering if I should use the polyurethane pads that came with them or not. The rear end is a mono leaf rear, so there is no hole to accept the tit on top of the spring. But I guess I can use the poly pad because it has a hole in it that would fill that void. But wouldn't using the poly pads allow the rearend to twist more by compressing the pads when accelerating and hard braking? I have some 1/2" steel that I could use to fill that void. Opinions? Thanks, Mark

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post #2 of 21 (permalink) Old Jan 18th, 02, 04:55 PM
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I trashed mine. But, i also replaced the center bolt w/ a carrage bolt of the same diameter and length that had a 1.5" flat "button" top that was about 1/8' tall above the top of spring. Got them at the hardware store Tightened the springs w/ the carrage bolt and a lock washer and lock nut. Placed springs between the perches and tightened "U" bolts to 50 ft. lbs.

The cool thing is that the perches will almost meet each other and will encapsulate all three springs! Kinda like the original mono w/ pads. This also places the shock mount (lower) in its original position as with the mono lower perches.
Didn't even have to align the pinion as it sat in its original position without any alignment shims. I had a 5 leaf multi spring (that replaced the original monos)that had to be shimmed prior to installing the Hotchkis 3 leaf springs.
I've now run the set up for over 3000 miles since installing them in Oct. 01. Seems to be a fine spring set.
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post #3 of 21 (permalink) Old Jan 18th, 02, 07:58 PM
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I'd leave out the pads if it were mine. Especially if it were a 67 with non staggered shocks. It might help prevent wheel hop for a 67.
I don't see any down side to leaving them out as long as you use a spacer plate on top.
I doubt ride quality will suffer at all. Many many cars dont use pads on the springs.

If you do use the pads the rear axle may rock slightly on the spring, probably not enough to make any difference.
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post #4 of 21 (permalink) Old Jan 19th, 02, 04:44 PM
 
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By a spacer plate do mean a steel plate with a hole in it to replace the upper pad so that the spring sits level in the rear axle?
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post #5 of 21 (permalink) Old Jan 20th, 02, 04:13 AM Thread Starter
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Yeah that's what I mean about the spacer plate. I decided not to use the pads. I got the springs in yesturday and everything went fine.
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post #6 of 21 (permalink) Old Jan 20th, 02, 08:02 AM
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Do it have to be a steelplate, can i use aluminum instead?
Or is it too soft for that?

The reason i asking is that i have some aluminum sheets. If im making 2 plates for each side(thats 4), they will be exactly the same hight as the pin. Or should the plates be little higher, or is it not a good idea to use 2 plates at all. Might slide or something?



[This message has been edited by MagnusRS68 (edited 01-20-2002).]
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post #7 of 21 (permalink) Old Jan 20th, 02, 08:49 AM
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The more you put below the axle, the lower the rear of the car will sit. That centerbolt head above the spring is about a 1/2 tall. You will need to place something that makes the upper contact flush with the upperperch. (add 1/2 inch of bar stock w/ center hole) Since some shim wedges are aluminum and used between the perches, it would probably be ok if it doesn't move. Then the upper and lower perches won't meet and appling 50lbs of torque to the U bolts will bend the mono lower perches. You'll probably have to opt for the multi leaf lower perches (they are stronger and won't bend) You'll still end up at 1/2 lower at the rear end.

Been ther done that.
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post #8 of 21 (permalink) Old Jan 20th, 02, 09:29 AM
 
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<BLOCKQUOTE>quote:</font><HR>Originally posted by joe clance:
I trashed mine. But, i also replaced the center bolt w/ a carrage bolt of the same diameter and length that had a 1.5" flat "button" top that was about 1/8' tall above the top of spring. Got them at the hardware store Tightened the springs w/ the carrage bolt and a lock washer and lock nut. Placed springs between the perches and tightened "U" bolts to 50 ft. lbs.
<HR></BLOCKQUOTE>

joe -
Please bear with me, I want to make sure I understand what you did. Also, please note my only visualization of the monoleafs and perches comes from looking at what is installed on the car. I have not seen these disassembled.

I have looked carefully at the mono perches on my car; as I look at the bottom (which is also the shock plate) I see what looks like a "nub" coming thru a center hole. There are pads installed, but it's not clear to me if this "nub" is a centering pin on the mono spring that sticks thru the pad or if the nub is part of the pad.

With your install, instead of using the center bolt supplied with the hotchkis springs, you replaced it with a carriage bolt that had minimal protrusion (1/8") above the top of the spring. This is lower than the 5/16" that the hotchkis bolt sticks up.

Then it sounds like you tightened the springs together and placed them in the perches, WITH NO PADS. What about the protrusion of the lock nut on the bottom of the spring? Does the lock nut fit thru the hole on the lower perch/shock plate?

Basically, it sounds like if the hotchis bolt is replaced as described above and no pads and no spacers are used, the hotchkis 3-leafs will fit almost just like the original monos. Is this correct?
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post #9 of 21 (permalink) Old Jan 20th, 02, 11:23 AM
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The nub in the pad you described receives the nut (of the center bolt)at the bottom of spring, and also protrudes thu the hole in the shock plate. If you eliminate the pads, only the nut will protrude thru the hole in the lower shock mount. If you can locate a similar carraige bolt like i used (it is of same lenght and width of the Hotchkis centerbolt) the install will be quite easy. The upper perch and lower shock plate will wrap tightly aroung all three springs (with no pads). The top of this replacemnet carraige bolt was about 1 and 1/2" in diameter(round) and 1/8 " tall. It will look like a 1.5 inch diameter button attached to the top of the spring when installed. This bolt (under the button ) starts as a lag bolt for about the first 1/4 " and i had to round them to completely enter the upper spring hole. This was so the bolt head would flatted against the upper perch when tightened. When it all tighten, the center bolt and nut protrude thru the lower shock mount hole. The lower shock plate almost meets the upper perch (&lt;1/4" separtion). This encapsulates all three springs.

The car sets in a nice position (i also replaced front spring w/ Hotchkis) and did not require a pinion angle change. If you change the placement of the rear axle, you will probably have to adjust for pinion angle. This happaned to me when i had a 5leaf multi leaf system before i installed the Hotchkis springs. Adding to the spring height changes the axle relationship and although 1/2" may not be noticed, you won't know till after its done. Can be frustrating when you have to go back into the rear spring and adjust pinion angle.
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post #10 of 21 (permalink) Old Jan 20th, 02, 11:30 AM
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<BLOCKQUOTE>quote:</font><HR>Originally posted by nasadude:
joe -
.


With your install, instead of using the center bolt supplied with the hotchkis springs, you replaced it with a carriage bolt that had minimal protrusion (1/8") above the top of the spring.

Yes, and is 1.5" in diameter..

This is lower than the 5/16" that the hotchkis bolt sticks up. Yes, Very much lower.

Then it sounds like you tightened the springs together and placed them in the perches, WITH NO PADS. What about the protrusion of the lock nut on the bottom of the spring? Does the lock nut fit thru the hole on the lower perch/shock plate?

Yes to all above.

Basically, it sounds like if the hotchis bolt is replaced as described above and no pads and no spacers are used, the hotchkis 3-leafs will fit almost just like the original monos. Is this correct?

yes to all above!
<HR></BLOCKQUOTE>

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post #11 of 21 (permalink) Old Jan 20th, 02, 12:24 PM
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Joe: Nice info, perfect for my upcoming rebuild of the rear.

But one thing i dont understand is that pinion thing, what is the pinion?

Thanks
Magnus
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post #12 of 21 (permalink) Old Jan 20th, 02, 12:47 PM
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Angle that the pinion (input the the rear gear) places on the universal joints of the drive shaft. It has been known to cause vibration when the angular relationship between the front and rear drive shaft u joints are @ &gt; 3* difference. When you change the height of the rear axle, you can change this relationship. If you look at the input of the rear differential, you'll notice that is probably aiming slightly downward and places a certain angle on the the rear U joint. This is the result if the upper perch weld placment. If you move the axle up or down, the pinion will remain at the same angle in relation to the ground, but, will impose a new angle on the rear U joint. The only way to correct it then is to change the angle of the pinion (now you will have to change it in relation to the ground) as well as the U joint angle. Gets Kinda complicated. I can say that the Hotchkis spring without adding pads, shims or bars, resulted in no driveline vibration.
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post #13 of 21 (permalink) Old Jan 20th, 02, 01:47 PM
 
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joe,

thanks for responding. No question now that I will be doing this myself and save some money.

I had wondered about the pinion angle myself, but decided I would cross that bridge when necessary. Hopefully, it won't be an issue as you say.
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post #14 of 21 (permalink) Old Jan 20th, 02, 10:53 PM
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Joe:
Thanks, i got it now. So i might get some vibration if im unluck, becasue im going to add a 9 mm spacer between the leafpin and axleperch.

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post #15 of 21 (permalink) Old Jan 21st, 02, 03:09 AM
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That not a lot, and may not make a difference to pinion angle. So, Probably not.
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