Vintage motorcars of Hawaiian Gardens offers an upgrade to their speedster of independent rear suspension for $2500. Has anybody had experience with and without this upgrade? Is it worth the cost?
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IRS is better.
It is worth getting if you're planning on driving the car hard, and want the best handling you can get out of a pan based car. However, for most folks a camber compensator on the standard swing axle is enough to keep them comfortable at quite a rapid clip.
This topic was covered in another thread last week. Here's a link to it:
https://www.speedsterowners.co...4#727404477096622134
A CMC Speedster is essentially the same as a Vintage in that they both use a VW Pan (chassis) underneath. That thread will explain why you need to use narrowed diagonal arms on an IRS pan with a classic sided Speedster body. If you have a wide body car, then there is no issue with the stock diagonal arms.
Thanks for the lead. Newbie here just learning how this thread works.
For the nicest riding and handling Speedster, irs is the way to go. Now, as mentioned, you can't get a wider tire/wheel combination under there and are limited to a 165-15 on a 4 ½" wide rim because the the tire will hit the fender lip, so hence the need for either narrowed trailing arms (along with shorter axles to make it all work) OR 4½" rims that have been cut apart and widened to 5½ or 6", the extra band welded to the BACK SIDE of the rim with a 175, 185 or possibly a 195 tire (the 195 may need some fender lip clearancing). With the right parts 7" rims are possible, and with a body "pie cut" 205's will fit, but now we're getting pretty involved. How much money do you want to spend?
I have a "regular" body, made by JPS in ~2006. IRS suspension. It is regular in the sense that the rear of the chassis is from a 72 beetle, complete with VIN. I run 185-15 tires and there is enough room between the tire and the fender edge to slip a dollar bill in between, but not much more. Apparently this gap gets larger as the suspension flexes, as I do not rub the tires while hooning. I could not tell you if I have narrowed trailing arms or not.
So to get tires that fit you must consider profile of tire and offset/backspacing --- in addition to tires size and rim width. Even CMC classic body cars can run 15" tires on 5.5" rims with stock drum brakes. Add disc rear brakes that often increase width and it pushes you to narrowed trailing arms or the body slice or 4.5" wide rims.
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@El Frazoo posted:I have a "regular" body, made by JPS in ~2006. IRS suspension. It is regular in the sense that the rear of the chassis is from a 72 beetle, complete with VIN. I run 185-15 tires and there is enough room between the tire and the fender edge to slip a dollar bill in between, but not much more. Apparently this gap gets larger as the suspension flexes, as I do not rub the tires while hooning. I could not tell you if I have narrowed trailing arms or not.
You don't, and you have 4-1/2" rims. That's how JPS did it.
Ohhh -- kaaaaay. What I am sure of is that the wheels and tires are round and they can roll really fast, when I want them to. So that's about as much as I know about all this, so far.
Gordon referenced my thread above where I was facing the same dilemma as you. Thanks to the feedback I got from the users here and advice from the guy building my pan, I decided to go with IRS.
I'm in the middle of this process so I can't comment yet on the outcome, but it seemed most people agreed that the handling is better with IRS when cornering hard.
I can add that while I do not completely understand all the high order mechanics involved, I did own two swing axle cars and have observed more than a few swing VWs in high duress while cornering, and that tucked in tire, lots of camber and such. Seen a lot of "decambered" cars too, VW and Porsche alike, trying to bias against that. Saw a FB video just today of a Beetle slamming it on a race track, and losing that grip so suddenly that the car flipped over. When presented with the build option: swing or IRS that choice was simple. I'll confess to having had a few (three or four) "nearly lost it" adventures with the Speedster, but did not. A couple were not pretty, but also not catastrophic. And a couple were downright exhilarating.