Shocks (was Fronts only)

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Shocks (was Fronts only)

Post by keithg on Mon Oct 01, 2018 10:30 am

These are pricey. The Bilstein custom ones are available at a number of placed. The Bilstein number is 55-R072 and they are 115/each. Not bad for a Bilstein, actually, but there have to be better options. On mine, my dad was able to find a shock of the correct length, but instead of a cross pin mount at the top, it had a stem. I took off what is on there. I can read "Gabriel, made in USA" and only part of a part number. I get 26x40. The x is the digit I cannot read. The lower mount is what the catalogs refer to as a XP2 which takes 2 5/16 bolts 2-3/8 apart. Best as I can measure, the max length is 15-1/8" and the min is 9-5/8".

Replacements: The top is fine as long as it is a stud, so S1-S6 would be fine by me. What the Gabriel shocks have is an S3 which is 3/8-24. I found a Monroe catalog and there are a couple options which may work. There are only a few with the XP2 lower mount and they may not fit as they do not extend as long. The ones I found are Monroe 32214/37066 which are 8.625/13 which may not extend enough. There are other ones are 5754 with XP1 lower mounts which are 2-3/16" which are 3/16" narrow. They may work just fine, though. I'll have to check. I found others which are about the right length, but these will have to be modded to accept the 2-3/8 center distance from the XP4 which is 2-7/16" or the XP5 which is 2-1/2" which can be done with a file. I can measure the full extension tonight to make sure, but this looks promising. Does anyone have a front sub frame without springs in it so we an get the absolute min shock length dimension?


Last edited by keithg on Tue Oct 09, 2018 8:37 pm; edited 1 time in total

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Re: Shocks (was Fronts only)

Post by 62cutlassconvert on Mon Oct 01, 2018 10:15 pm

Shocks2springs has shocks for these cars. I think they are Gabriels set up for our mounts. Front- hydraulic or gas charged, Rear Hydraulic, gas charged, spring over/overloads, and air. Probably twice the price of the shock for say a 1964 Chevelle for which you can by a standard Gabriel.

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Re: Shocks (was Fronts only)

Post by custom880 on Tue Oct 02, 2018 2:04 pm

if this helps any, these shocks have crossbars, like on the bottom of this shock, on the uppers and lowers. Sounds like you might have a different set up.

monro-matic
pat. re23421, 2070364, 2546038
other# 3020 and 11c7
compressed 10 3/4 eyelet to eyelet
extended 15 3/4
came off of my parts car. went to autozone they couldn't cross. did a little research couldn't find anything. maybe you'll have better luck.

replacement rubber for washers on subframe. used 1/4" 70d shore if I remember stuff left over from another work.

beveled the edge to sit a little higher than center of washer. cut original hole with the largest step drill I had.

will use a scroll saw for finish shape. Best I can come up with so far.
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Re: Shocks (was Fronts only)

Post by keithg on Tue Oct 02, 2018 4:11 pm

The compression info is useful. That 10-3/4" is center to center of the eyelets? It is a lot shorter than mine. I measured this morning and with the shock out and to the top of my bracket, it is 15-1/8", subtract the 1/4" of bracket and 5/8" thickness of the rubber grommet and I have a max stroke needed of 14.25. That is a lot longer than the 10-3/4" you measured. It would be difficult to get them on if I had to compress the suspension over 3"!

The shock I have was 9-1/2" and 15-1/8" compressed/extended. The OEM has the yoke type mounts. They are called XP2 which is 5/16" bolts 2-3/8" apart. Very few use XP2 on either end, any more. My car was owned by my dad and he adapted some Gabriel shocks in the 70s by making a 1/4" strap with 3 holes for the stud mount and had an XP2 at teh bottom. I suspect is is NLA:

Picture of top mount

The nearest I can come up with is a Monroe 550012 which is for a 71-96 Caprice which has an XP4 which is 2-7/16 in spacing on the lower mount and has a top stud mount 3/8-16. The stroke is from 9.375 to 14.5. I will have to take a 1/32" off each side of the bracket which will be pretty easy with a file. I can get a set of A/C Delcos for $15.00 each from Rock Auto:

ACDELCO 520168

The bracket is way overkill, but is 1/4" thick. You could get some material from the hardware store and duplicate it pretty easily.

Bracket Drawing

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Re: Shocks (was Fronts only)

Post by custom880 on Wed Oct 03, 2018 6:22 pm

I thought making a bracket on top and actually found a set of shocks at autozone that had the xp2 on the bottom and pretty close to the same dimensions. May have to go back and check it out again. It center to center.
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Re: Shocks (was Fronts only)

Post by keithg on Sat Oct 06, 2018 8:39 am

I put the delco shocks on the front last night. The lower mount was too long. There is a slight dish in the A-arm where it mounts and I had to take a cutoff tool and cut the ends off. The holes were large enough that I did not have to file the center distance any.
Comparison
Modified

Piece of cake.

The old ones were Gabriel 26040 which does not come up in any product search. I was able to determine the number a bit easier on the RF shock. Really does not matter, though as a 71-96 caprice should allow you to find some at any parts house. That or the GM number: 88946013. The rear shocks are still available at normal parts houses.

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Re: Shocks (was Fronts only)

Post by 62cutlassconvert on Sat Oct 06, 2018 8:53 am

Maybe I'm misunderstanding but are you using shocks for a 71-96 Caprice on a Skylark? The Caprice must weigh about 1000 lbs more so shocks would be much different (higher) damping. On the other hand the stock early 60s shocks were mush. So how do they feel?

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Re: Shocks (was Fronts only)

Post by keithg on Sat Oct 06, 2018 9:22 am

the front shocks respond with force proportional to velocity. The springs support the weight. The corner 'unsprung mass' (knuckle, a-arms, tire, wheel, and spring rate) and the geometry are the critical bits when evaluating shocks. As a tire undergoes a pulse input, the shock pushes back with a force proportional to how fast it is moved. The other critical bit is the geometry and the spring rate, where is the shock located on the a-arm and how long is the a-arm to determine the proportionality of the velocity input. The weight differential of 1000lb, is divided by 4 wheels, so lets say there is a differential in spring rate between the 2 of 250 lb/in. In my 'thumb in the wind' engineering approximation, we are 'close enough' as a comparison of the unsprung masses and the geometry. I have not driven it, yet. It started raining last night when I got them on. I'll report back after it stops raining here in Chicago, but I guess they will be acceptable for 15.00 a pop. I did not get 'heavy duty', which are stiffer, but 'stock gas charged' which should be a close to OEM for the Caprice, at least the later models. If I need to go softer, there are other options. I'll let you know.

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Re: Shocks (was Fronts only)

Post by 62cutlassconvert on Sat Oct 06, 2018 11:39 am

I obviously do not have the grip on this that you do but I have a couple of questions.
Don't shocks for a heavier car provide increased resistance in the valving?
So 2700 lb skylark/4=675 per corner. 3700 lb Caprice/4=925 per corner. So that's a 37% increase in weight per corner for the Caprice shocks. Pretty significant. But I understand obviated to some degree by the springs and geometry.
But would they not be "stiffer" shocks as a baseline just to control the increased mass they are controlling?

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Re: Shocks (was Fronts only)

Post by keithg on Sat Oct 06, 2018 7:04 pm

I would not say I am an expert, but my experience is that stiffer springs (lowering for whatever reason) will require stiffer shocks due to the shorter travel and higher spring rate. On another car, personal experience, if you have the performance springs and try to use OEM shocks for the normal springs, it is a disaster. It just feels uncontrolled like teh spring is doinh what it wants and no shock to damp the motion. Uncontrolled wheel compression/ extension and a harsh ride. These springs need the heavy duty shock to counter the extension as well as the compression. The Skylark has, what I assume to be, original front springs which are actually pretty stiff compared to larger/heavire cars I have experienced. Go and try to push the fender down to see what sort of oscillation you can induce in the garage. It is pretty stiff on my car, anyway.

My understanding is that you hit a bump and the spring compresses as does the shock and it needs to generate force to slow down that impact to limit the 'up' travel of the tire/wheel. Once compressed, the spring will try to extend this to bring the wheel/tire back down to and this extension has a different valving to the compression side. There is definitely math as well as testing to get the optimal spring/shock combination, but with this old cart, there are not a lot of options. I question of the shocks2springs Bilstein shocks are much different than the delcos I just got.

Yes, there can be different valving, but IMO, shocks for any American car I've driven are almost always too soft for me so I usually go for HD shocks which are stiffer. In this case, I went with OEM which should be a bit softer for the lighter car. The 'body float' may be due to too little preload on the valve shim stack and/or not enough shock travel to actually generate the force needed. Compression is to counter a bump and rebound is for extension.

I drove it around this afternoon a bit. definitely more controlled. Also not harsh. The gas pressure does appear to raise the front ride height by a bit. I give these a 'thumbs up' if anyone is interested. Way better than the old ones that had leaked out all their gas and probably most of their oil.

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Re: Shocks (was Fronts only)

Post by keithg on Sat Oct 06, 2018 8:00 pm

Thinking about this a bit more. The rear shocks are Delco 520-182. They are for our skylarks as well as camaro/firebirds '68-'69 as well as a '64-'72 vista cruiser and a '64-'69 skylark wagon...
The 520-182 fronts I got are for camaro '70-81 as well as full size pontiacs/olds/chev and buick. As far as I can tell, there is a lot of engineering that goes into these at the beginning, but in the end there are mostly mounting and length differences and quality levels. No gas charged, gas charged, heavy duty. Also I am guessing the shock lengths are also proportional to the velocities which are related to the suspension geometry. Longer shocks are connected closer to the wheel and move through more distance and can have looser valving because they move more. When you look at it, most GM style front ends from this era have the shock through the spring mounted mid way on the a-arm. My Saab has double wishbone as well, but the shock is mounted almost at the ball joint and is much longer so its velocities are much greater. For a shock designer, I would think this allows for a larger range of adjustment than what we have on the Skylark and, by extension, most of the GM cars from the 50s through the 80s...

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Re: Shocks (was Fronts only)

Post by keithg on Sun Oct 07, 2018 7:09 pm

So after the front shocks, I decided to go to the rears. The 520-182s I got from RockAuto do not fit. They have a stud at the top which will not work. I'll send them back, but would like to get a set of something to put on it. I went under the car and took some rough measurements. It looks like they are 14" compressed and 23-1/4 extended (center to center of each loop). The lower mount looks like a CP1 and the top looks like a LS12. I did not remove it from the car, yet, so this is very preliminary. There are fewer options for the rear because the upper and lower are loop style mounts and the diameters must fit. Mine are Gabriels from the 70s and I do not know if they are OEM replacement or not. If anyone has any OEM shocks that they can measure, I'd appreciate it.

What I need to know are the diameter and length of the tube through the upper mount. My guess is that it is a LS12 which is 7/16 ID and 1-1/4" long but without removing the shock I do not know exactly. The lower mount of my shocks accepts bushings for an L1, so it looks like an L1/CP3 which is 5/8" ID on the bushing and 1-5/16" long. The rubber is deteriorating on these, but they seem to have some shock action though they are no longer charged, so the gas has leaked out.

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Re: Shocks (was Fronts only)

Post by keithg on Tue Oct 09, 2018 8:49 pm

Well, Rockauto will not pay shipping for their problem until I give more informaiton. I tool the RR off tonight. It is a Gabriel 45247. It is 14" compressed and 23-3/8" extended. The upper mount is a L1/CP3 (5/8 stud through a rubber bushing 1-1/8" long) and the upper is an LS14 which is a 7/16 ID tube 1-3/8" long. I am pretty sure the upper could be L1 or LS14 and it would be OK. Problem is the only shocks I can find are for trucks and pickups.

I found a set for a 65 Riviera 520-378. The mounts are upside down, but I am pretty sure I can push the steel tube out of the lower bushing and put it in the upper bushing. The lengths are close 14-5/8" and 24-7/8"

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Re: Shocks (was Fronts only)

Post by keithg on Fri Oct 12, 2018 10:35 am

In addition to the Riviera, I found that 65-70 Caddy Deville shocks are the right length and you can get air shocks for it, too. I'd like to re-align the ride height so it does not look like it has a load in its pants. Delco 520-379 and Monroe 5757/MA728. The MA728 are the air shocks. When you remove the old shocks, just keep the tube out of the upper mount or make one 7/16ID, 5/8OD,1-3/8 long and they should bolt right up. I'll post back as a confirmation, but this is what I will do.  Have not decided if I am going with air or not.

I made a spreadsheet out of the PDF and can actually sort the sizes as needed to find what may fit. I then used Monroe/Rockauto to find out which ones fit what vehicle.
The link is here: Shock Length Spreadsheet

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Re: Shocks (was Fronts only)

Post by 62cutlassconvert on Tue Oct 16, 2018 9:07 am

If your rear end is sagging you need springs. Regular shocks will not effect ride height much. Air shocks will make you car ride like a rock if they are not loaded with a full trunk or trailer etc.

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Re: Shocks (was Fronts only)

Post by keithg on Tue Oct 16, 2018 9:29 am

That is my plan. Regular shocks and new springs. Is shocks2springs the place to get them? I seem to remembera mention of another place at some other time.

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Re: Shocks (was Fronts only)

Post by 62cutlassconvert on Tue Oct 16, 2018 10:23 pm

I got 1" lower springs from Detroit Eaton Spring, drops it a little for better handling and looks imo and maintains stock spring rate. Not the same as cutting the coil. Fusick has stock ones for the Olds F85 line, I guess those are the same as Skylark but I don't know for sure. I think springs are available lots of places. I would think a Buick supplier has them too.

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Re: Shocks (was Fronts only)

Post by keithg on Sat Oct 20, 2018 7:41 pm

Installed the Monroe 5757 today. Piece of cake. You get a lot of hardware which will not fit with the shocks. You must re-use the lower mount and push the sleeve out of the upper mount of the old shock (or make one: 5/8" OD 15/64" ID 1-3/8" long) and push it in the upper mount. The ride is nice. Not harsh. Better than the dead, 30+ year old Gabriels that came off.

I'd recommend these to anyone for front and rear.

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Re: Shocks (was Fronts only)

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