Rear Shocks for 8”

[seriesIIIgt]

help looking for a part number for rear shocks l need shocks to have stud mounting top and bottom
I bought Koni 82-1389 for mustangs 65-73 but are to short
Talked to koni about getting the same style but longer they can only go by vehicle
I have 18.5” mounting points
Thanks Geoff

 

[Barry]

18.5" compressed, extended or ride height?

Why did you buy Koni rear shocks for a '65-'73 Mustang?

 

[seriesIIIgt]

18.5” ride height weight of car on the tires nothing in the trunk
I talked to a friend that has a mustang he measured his collapsed and extended and was very close to the one that was on my stock rearend
I didn’t take into the fact that the Alpine mounts different on the bottom so the overall shock is longer

 

[Barry]

A shock that is 18.5" at "ride height" means about 13-14" compressed and about 22-23" extended. That is a VERY BIG shock for a small car.

The Alpine rear shock is about 15.5" at ride height and the lower shock mount is about 5" below the axle centerline.

A shock that is 18.5" at ride height would require the lower shock mount to be about 8" below the axle centerline which seems like a lot.

If you insist on using a rear shock that is 18.5" at ride height, a Monroe # 32286 is 13.5" compressed and 22.125" extended and has double stud mounts. The application is '70's F-150 / 250 / 350 pickups, so the ride might be a little "firm" on an Alpine. No idea if Koni makes something suitable or what the price might be.

If you want to go digging, try here: http://www.monroe.com/downloads/install-instructions-guides/MonroeMountingLengthSpecifications.pdf

Not something I would do and I seriously doubt that Koni would approve, but you can get "shock extenders" that increase the shock length by 3".

https://www.summitracing.com/parts/sum-727000​

 

[seriesIIIgt]

Barry
Maybe lam measured wrong
From under the car l measured from the body where the stud goes through to the top of steel platel hadl made that bolts onto one of the u-bolts that hold the axle in place

 

[Barry]

Geoff,

Looks like I was at least partially wrong about the rear shock length at "ride height".

Part of the problem is defining the normal ride height and I have not been able to find any relevant technical literature.

As typical of British cars in the '60's, stock Alpines seem to consistently sit high in the front / low in the back. I suspect that some of the "low in the back" results from sagging of the leaf rear springs over time, but .....

Based on observation and pictures, most "stock" series Alpines seem to have the top of the rear fender arch about 1" above the top of stock diameter (23") tires. Another way of saying that is the top of the rear fender arch is about 12-1/2" above the axle centerline.

I finally got to a situation where I could accurately measure the rear shock lengths at various ride heights on my S-V with a stock axle (lower shock mount ~4" below the axle centerline). With the top of the fender arch 12-1/2" above the axle centerline, the shock length on my S-V is 17-3/4". Note that the measured shock length is affected by both the ride height and the lower shock mount dimensions.

For 6" of rear suspension travel, the compressed and extended shock lengths would have to be less than 14-3/4" and more than 20-3/4". Some of the modern shocks recommended for Alpines have up to 8" shock travel, but I doubt that the Alpine had that much rear suspension travel.

Sorry for the previous bad information.

 

[seriesIIIgt]

Hi Barry
Thanks for turning me onto Monroe l talked to a guy there and he helped me get the right shocks
I think it was the same part number that you gave me
I ordered them and they worked perfectly
Thanks Geoff

 

[Barry]

Glad to hear it worked out in spite of the process being a little ugly.