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dannyp84
dannyp84 Reader
10/7/22 11:10 a.m.

In reply to Pete. (l33t FS) :

I've had to replace both clutch cylinders twice in the last 16 years and 90 k mi, but I've never touched the stock clutch itself even after 6 or 7 years of drifting.I drove mine for the first time in 2 months last night after refreshing some front suspension parts, it felt good to be home.

Miatagrin
Miatagrin New Reader
10/16/22 8:03 p.m.

Where do owners of the first gen RX-7 get stock'ish 13" tires?  The car is driven as a summer/weekend car, so I'm not looking for autox or track tires.  Any help would be appreciated.  Very awesome seeing pics of other first gen cars.

Pete. (l33t FS)
Pete. (l33t FS) GRM+ Memberand MegaDork
10/16/22 8:13 p.m.

In reply to Miatagrin :

Stock were H rated Bridgestones.  Good luck finding H rated 185/70-13s anymore smiley

205/60-13 BFG Radial T/A tires look period correct, fit well (a couple percent shorter than stock), and they work well with the first generation cars' notoriously wander prone steering.

On that note: 90% of the time it is loose wheel bearings. 10% of the time it is sloppy control arm bushings or ball joints.  People try to fix those issues by cranking down the adjuster on the steering box, which destroys it.  It is recirc ball steering, it is SUPPOSED to have a small dead area on-center and a progressive buildup when loading it.  Trying to tighten the steering to fix wandering is attacking a driver expectation error, not the reason why it wanders.  You can and should be able to drive the car no-hands. 

People try to cheap out and replace worn bushings with polyurethane.  It is an upgrade, right?  In practice, the poly bushings have a small degree of slop under neutral load and they made the wandering worse, not better.  The downside of rear-steer geometry is that play in the control arm equation leads to a positive feedback loop for toe-in.

Also, they drive much better with half a degree or so of positive camber in the front.  The steering finds its own center better and the steering feel is much lighter.  It is not like these cars need more front grip.

dannyp84
dannyp84 Reader
10/16/22 9:06 p.m.

In reply to Pete. (l33t FS) :

I actually checked for wheel bearing play on mine earlier today and they're due to be snugged up a little. Drove the car yesterday and it will track straight down the road with no hands despite somewhat aggressive alignment specs for track purposes.
Have you ever noticed that to get a socket on the lower caliper bracket bolt, you first have to unbolt the spindle from the steering knuckle so you can move them independent of each other? Otherwise the knuckle is too close to the bolt to access. One of very few inconveniences I've noticed after messing around with this car for 16 years, it's otherwise fairly easy to service.

Pete. (l33t FS)
Pete. (l33t FS) GRM+ Memberand MegaDork
10/16/22 9:31 p.m.

In reply to dannyp84 :

We used to cut a little bit off of that bolt and omit the washer to make life easier.

Around here, trying to move those strut housing bolts usually meant the bolts would break off due to rusting to the steering arm.  Slip fit turns into an interference fit stronger than the bolt head. 

Which is why I had to Sawzall the strut apart on my '85 about twenty years ago.

So the easy way is to back off the bolt with a box end wrench, then use an open end wrench, then loosen the wheel bearing so you can slide the rotor out so you can move the caliper bracket out so you can get the bolt the rest of the way out.

 

Yeah, a bit of a pain!  But there are handling benefits to having the caliper on the back, so Mazda did it that way.  It is to be noted that after Hyundai snagged certain BMW personnel to do their chassis, they started putting the front calipers on the back of the spindle, too.  You can remove the caliper on those without difficulty but you also have to remove the caliper to get the tie rod off.

Pete. (l33t FS)
Pete. (l33t FS) GRM+ Memberand MegaDork
10/16/22 10:22 p.m.

Just because I found a cache of old pics, including that one from when I was half my age but somehow look the same as now.

 

15" Weds wheels on 195/50 tires.  These wandered horribly.

 

Zero offset 13x7 Diamond Racing wheels and 205/60-13 RE71R tires.  The original ones.  I could get two whole laps out of them at Nelson Ledges before they would get all greasy.  Maybe that is why I rallycross now.

 

Way in the back, 15x7 Kosei K1s, because they used to drill them to whatever you wanted and this was the only wheel option for 4x110 for a long while.  And the car came with them.

jmabarone
jmabarone Reader
10/17/22 8:09 a.m.
dannyp84 said:

In reply to Pete. (l33t FS) :

I actually checked for wheel bearing play on mine earlier today and they're due to be snugged up a little. Drove the car yesterday and it will track straight down the road with no hands despite somewhat aggressive alignment specs for track purposes.
Have you ever noticed that to get a socket on the lower caliper bracket bolt, you first have to unbolt the spindle from the steering knuckle so you can move them independent of each other? Otherwise the knuckle is too close to the bolt to access. One of very few inconveniences I've noticed after messing around with this car for 16 years, it's otherwise fairly easy to service.

When I pulled the caliper brackets off to install brake ducts, I cut away the lip on the bracket to access the bolt with a ratcheting wrench.  

dannyp84
dannyp84 Reader
10/17/22 10:08 a.m.
Pete. (l33t FS) said:

In reply to dannyp84 :

We used to cut a little bit off of that bolt and omit the washer to make life easier.

Around here, trying to move those strut housing bolts usually meant the bolts would break off due to rusting to the steering arm.  Slip fit turns into an interference fit stronger than the bolt head. 

Which is why I had to Sawzall the strut apart on my '85 about twenty years ago.

So the easy way is to back off the bolt with a box end wrench, then use an open end wrench, then loosen the wheel bearing so you can slide the rotor out so you can move the caliper bracket out so you can get the bolt the rest of the way out.

 

Yeah, a bit of a pain!  But there are handling benefits to having the caliper on the back, so Mazda did it that way.  It is to be noted that after Hyundai snagged certain BMW personnel to do their chassis, they started putting the front calipers on the back of the spindle, too.  You can remove the caliper on those without difficulty but you also have to remove the caliper to get the tie rod off.

What's the handling benefit to the rear caliper setup? Those strut housing to knuckle bolts on my car have been in and out so many times over the last decade that they don't get much time to corrode. Also I've been pretty diligent in keeping the car out of winter weather. Despite those efforts, I've had the rear wheel  tubs cut out and repaired as they rusted from the inside out, and my lower rear quarter panels or "pockets" as the guys in Ireland call them are pretty crusty these days. The floors and rockers are still nice and clean though.

jmabarone
jmabarone Reader
4/11/23 10:38 a.m.
dannyp84 said:

 

What's the handling benefit to the rear caliper setup? Those strut housing to knuckle bolts on my car have been in and out so many times over the last decade that they don't get much time to corrode. Also I've been pretty diligent in keeping the car out of winter weather. Despite those efforts, I've had the rear wheel  tubs cut out and repaired as they rusted from the inside out, and my lower rear quarter panels or "pockets" as the guys in Ireland call them are pretty crusty these days. The floors and rockers are still nice and clean though.

Keeps mass within the wheelbase, which leads to better handling.  Rear mounted calipers also allow better brake ducting.  

Pete. (l33t FS)
Pete. (l33t FS) GRM+ Memberand MegaDork
4/11/23 1:21 p.m.

In reply to jmabarone :

There is some chassis dynamic benefit to having the mass behind the steering axis instead of ahead of it.  The whys and wherefores are beyond my expertise, though.

j_tso
j_tso Dork
4/11/23 7:49 p.m.

maybe to have the caliper clear the sway bar on full lock?

 

I'm not sure about handling, other cars like the AE86 Corolla, S13 240SX, and NSX have their calipers clocked towards the front.

Definitely better for brake ducts on a race car.

Pete. (l33t FS)
Pete. (l33t FS) GRM+ Memberand MegaDork
4/11/23 8:09 p.m.

The calipers don't come close to the stabilizer bar, but it is interesting to note that some production time period of GSL-SE had brake ducts from the factory.

 

I'm seriously wracking my brain re: caliper clocking... maybe puts the upright's center of mass closer to alignment with the tire's contact patch-strut upper mount axis?  It was on an eng-tips thread a long while back and I couldn't even begin to remember how to find it, let alone my username/password.  It was important for steering feedback/feel.

 

 

sergio
sergio HalfDork
4/12/23 9:40 a.m.

My 85 GSL-SE with 148k I bought on BaT in 2016. California car, original owner had it til 2013. Second owner had it painted and fixed a few details on it. I drove it from L.A. to Houston, got 20mpg, did 125mph out in West Texas. Put some RB springs with Tokicos on, a Moog idler arm, drives really well, smooth, no rattles. Just about every time I drive it someone says they had one back when they were new. 

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