Drop spindles?
01-04-2017, 09:36 PM
#1
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Car: 1991 Trans Am GTA
Engine: L98(5.7 L TPI)
Transmission: 700r4(A4)
Axle/Gears: G80 RPO, 3:23s, Auburn Racer's Diff
Drop spindles?
I have a 1991 Trans Am GTA. Back in 2008, I purchased a wilwood brake kit from Ed Miller. It was the largest brake kit that would fit under stock GTA wheels.
My car is in the shop right now. A bolt from the caliper bracket that bolts into the spindle came loose. The spindle was damaged and it now needs to be replaced. (What can cause this issue? My guess is the mechanic who installed the brakes didn't tighten the bolt enough.)
Since I have to replace the spindle, I figure now is the time to upgrade. My long term goal is to put 17 or 18 inch wheels on the car. I would like to use larger diameter tires and then lower the car to stock ride height. By doing this, I want to fill up the wheel wells without rubbing and with keeping the stock ride height. (I don't mind rolling the fenders and I don't mind minor, tasteful trimming.). Are these goals attainable?
To lower the car, I heard drop spindles are best since they maintain the stock suspension geometry. Is this correct? What are the disadvantages of using drop spindles?
If I decide to install drop spindles, which are the best available? Will they be compatible with my brakes? (According to my mechanic, 3rd gens with single caliper brakes use different stock spindles than those with dual caliper brakes. Are different drop spindles made for different brake setups?)
Also, am I correct in that the rear of the car doesn't have spindles due to the solid axle? If so, what's the best way to lower the rear of the car?
While the spindles are being replaced, are there any other worthwhile upgrades or maintenance that should be performed like wheel bearings, ball joints, etc? I figure I'll need new springs since lowered car + sagging original springs = scraping.
Thanks for your help!
Bill
My car is in the shop right now. A bolt from the caliper bracket that bolts into the spindle came loose. The spindle was damaged and it now needs to be replaced. (What can cause this issue? My guess is the mechanic who installed the brakes didn't tighten the bolt enough.)
Since I have to replace the spindle, I figure now is the time to upgrade. My long term goal is to put 17 or 18 inch wheels on the car. I would like to use larger diameter tires and then lower the car to stock ride height. By doing this, I want to fill up the wheel wells without rubbing and with keeping the stock ride height. (I don't mind rolling the fenders and I don't mind minor, tasteful trimming.). Are these goals attainable?
To lower the car, I heard drop spindles are best since they maintain the stock suspension geometry. Is this correct? What are the disadvantages of using drop spindles?
If I decide to install drop spindles, which are the best available? Will they be compatible with my brakes? (According to my mechanic, 3rd gens with single caliper brakes use different stock spindles than those with dual caliper brakes. Are different drop spindles made for different brake setups?)
Also, am I correct in that the rear of the car doesn't have spindles due to the solid axle? If so, what's the best way to lower the rear of the car?
While the spindles are being replaced, are there any other worthwhile upgrades or maintenance that should be performed like wheel bearings, ball joints, etc? I figure I'll need new springs since lowered car + sagging original springs = scraping.
Thanks for your help!
Bill
01-04-2017, 10:59 PM
#2
Re: Drop spindles?
You're doing it wrong. You run larger diameter wheels and the same diameter tires. If you're trying to go monster truck with taller tires, first you're going to murder your gear ratio. Second, if you go lower AND go taller tires, they're going to rub. A meaty 245/50R16 will rub before hitting the steering locks.
01-04-2017, 11:30 PM
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Car: 1991 Trans Am GTA
Engine: L98(5.7 L TPI)
Transmission: 700r4(A4)
Axle/Gears: G80 RPO, 3:23s, Auburn Racer's Diff
Re: Drop spindles?
Drew,
Thanks for the input. I don't mind taller gears to compensate for taller tires. I swear most of the guys I've seen on here with 18s have to be running larger wheel diameters than stock. Shouldn't taller tires be fine as long as they aren't wider than stock?
My overall goal is to fill up the wheel wells while maintaining the stock ride height.
Thanks for the input. I don't mind taller gears to compensate for taller tires. I swear most of the guys I've seen on here with 18s have to be running larger wheel diameters than stock. Shouldn't taller tires be fine as long as they aren't wider than stock?
My overall goal is to fill up the wheel wells while maintaining the stock ride height.
01-05-2017, 11:02 AM
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Car: 91 Z28, 87 SC, 90 IROC, 92 RS
Engine: LS1, 305 TPI, L98, NADA
Transmission: T56, 700r4's, and NADA
Axle/Gears: 3.89, 3.42, 3.23, NADA
Re: Drop spindles?
Nobody makes a drop spindle for a street car anyway so might as well go back to the drawing board.
I have no clue why you want a taller aspect ration tire. Move the wheel size up and keep tire diameter close to same, as it has already been mentioned
I have no clue why you want a taller aspect ration tire. Move the wheel size up and keep tire diameter close to same, as it has already been mentioned
01-05-2017, 12:57 PM
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Car: '85 Camaro
Engine: LG4
Transmission: 4L80E
Axle/Gears: 3.42:1
Re: Drop spindles?
Lowering aside, plus 1 sizing works like this: 245/50R16 = 25.65" 245/45R17 = 25.68" 245/40R18 = 25.72".
These wheelwells are about 30" long, that's why 29" drag tires fit the rear. In front, the steering limits that.
Looking at stock and lowered,the common 25.7" tires don't fill the wheelwells either way, but seem closer to filling them when lowered.
There's no such thing as a 245/50R17, AFAIK, but it would fill the wheelwell more than a 245/50R16, and the tire sidewalls seem shorter because the wheels look taller. A 245/50R17 would be 26.65", and that is practical, because the '82 Indy Pace Car Z28 ran 245/60R15s, at 26.6". But it wasn't lowered at all.
Filling the wheelwells the other way, going from a 245/45R17 to a 275/40R17, there's another 1.2" of width, but no change of tire diameter, the 275 is 25.66".
I have seen 275/40R18s fitted front and rear, on Corvette 18x9.5" wheels, and there was visibly less gap in the wheelwells. The guy showed me where he had to hammer to keep them from rubbing at full steering lock, it wasn't much. Those wheelwells looked full until I got on here and found the section for wheels and tires.
How much wheel you want is mostly up to your tastes and money, but filling the wells with small wheels and tall tires looks bad and performs bad. Taller wheels allow more width, bigger brakes, more clearance for bumpsteer kits and extended balljoints, less unsprung weight, less rolling mass, it's all win, up to a point.
Me, I wouldn't settle for a 245/45R17 since i can fit 275/40R18, for example. But build your car to suit you. You're the one who has to live with it, and should enjoy driving it.
A 275/35R18 should give slightly more ultimate performance at the extreme limits, than a 275/40R18, but in daily use I'd never know the difference, and I'd feel better driving it if I felt that it looked "right". For racetracks I don't drive at, there are threads about going even wider than 275s, I just used them as an easy example.
Bell Tech used to make dropped spindles for these cars, but they were priced too high to sell. Triple the sales at half the profit would have made them profitable after a while, but as it turned out they never recouped their investment. Greed got it's just rewards, but at our expense.
These wheelwells are about 30" long, that's why 29" drag tires fit the rear. In front, the steering limits that.
Looking at stock and lowered,the common 25.7" tires don't fill the wheelwells either way, but seem closer to filling them when lowered.
There's no such thing as a 245/50R17, AFAIK, but it would fill the wheelwell more than a 245/50R16, and the tire sidewalls seem shorter because the wheels look taller. A 245/50R17 would be 26.65", and that is practical, because the '82 Indy Pace Car Z28 ran 245/60R15s, at 26.6". But it wasn't lowered at all.
Filling the wheelwells the other way, going from a 245/45R17 to a 275/40R17, there's another 1.2" of width, but no change of tire diameter, the 275 is 25.66".
I have seen 275/40R18s fitted front and rear, on Corvette 18x9.5" wheels, and there was visibly less gap in the wheelwells. The guy showed me where he had to hammer to keep them from rubbing at full steering lock, it wasn't much. Those wheelwells looked full until I got on here and found the section for wheels and tires.
How much wheel you want is mostly up to your tastes and money, but filling the wells with small wheels and tall tires looks bad and performs bad. Taller wheels allow more width, bigger brakes, more clearance for bumpsteer kits and extended balljoints, less unsprung weight, less rolling mass, it's all win, up to a point.
Me, I wouldn't settle for a 245/45R17 since i can fit 275/40R18, for example. But build your car to suit you. You're the one who has to live with it, and should enjoy driving it.
A 275/35R18 should give slightly more ultimate performance at the extreme limits, than a 275/40R18, but in daily use I'd never know the difference, and I'd feel better driving it if I felt that it looked "right". For racetracks I don't drive at, there are threads about going even wider than 275s, I just used them as an easy example.
Bell Tech used to make dropped spindles for these cars, but they were priced too high to sell. Triple the sales at half the profit would have made them profitable after a while, but as it turned out they never recouped their investment. Greed got it's just rewards, but at our expense.