speedgoat

My 99 SS is at the dyno shop now and the guy cant drive it onto this dyno. The dyno in question is a mustang dyno where the rear wheels sit between the rollers rather then on top. When he drives it on my muffler (slp dual/dual)hits the floor. Anyone else ever run into this? He says he's never had this problem before and he's tuned tons of these cars, probably most of the modded f-body's in the portland/vancouver area. What can I do short of cutting the exhaust off?

Steve Gunn

cut it off or temporarily stuffing stock springs in the back might be easier. or a cheap set of air shocks. Or even a temp spring perch.

JetMech99

iTrader: (3)

Can't he get some planks of wood or something to lessen the angle? I've used this method many time to load and unload lowered cars onto trailers.

Latch

iTrader: (8)

Good god how low is your car?!

DoggyB22

iTrader: (2)

Yea seriously.... Is your car really THAT low? I don't understand why they can't just use wood to raise it up. Just take it to another dyno shop haha doesn't sound like they know what their doing

ULTIMATEORANGESS

iTrader: (4)

where i go they have a mustang dyno and they have ramps to adjust for different heights. vettes are pretty low and they never have a problem.

99SSJarhead

iTrader: (2)

The problem the way I read it is that when the car sits between the two rollers, his rear sits to low and his muffler rests on the ground. Not that he can't roll onto the dyno itself. Changing the angle is just gonna make it worse. Is your muffler in front of or behind the axle?

The only real piece of advice I can give is as was said by poster #2, stock height rear springs long enough to get it tuned.

Orange Juice

iTrader: (3)

Could you not just jack it up, let the rear axle hang. Put some kind of shim or blocks between the spring coils. Lower back down again and put it on the dyno.

red1998z28

iTrader: (1)

Why don't you just take the cat back or muffler off?

BobDoLe

iTrader: (11)

spring spacers!



i used to pick those up from pep boys, jack up my car (old 4cyl import), throw them in, then take it offroading. eventually they would fall off on a jump though...

themealonwheels

iTrader: (20)

Guys, wouldn't adjusting his suspension change for dyno tuning also mess with his pinion angle/rear axle geometry, thus causing bad numbers and possibly damage to the drivetrain? If you've corrected your pinion angle and axle location for the lowered suspension, I would hesitate to throw springs on it for dyno time. Use wood planks to get it there.

speedgoat

So just an update on this. Thanks for all the suggestions on using blocks, that ended up being the solution. I think my bumper is hanging down lower then it should because my car is not that low (about 2 fingers between tire and fender).
Anyway I watched the car go on the dyno and it did hit the ground. On this dyno you drive up in between 2 rollers and there's a little metal plate that the tires sit on. That plate then gets lowered so the tires drop down onto the rollers themselves. When we did this the muffer would hit the ground and going all the way down woud have probably caused damage.
The solution we came up with was to put a 4x4 block under each of my sub frame connectors so the back of the car didnt drop down as far. This ended up causing the tires to burn out on the rollers at WOT so I aired up the rears to 40psi and that worked.
Everything was fine after that. By the way I got 376rwhp/366rwtq from bolt on's and a small 224/224 112 cam.