Changing wheel stud PCD

Craig C · Postby **Craig C** » 24 Mar 2011 01:21

Whoops, my bad...

After a little googling it seems standard wheels on the early Zeds were 4.5jj x 14 with 175 tyres. They just looked like 13s[;)]

They still look hot with 17's!

Craig

ColoradoTR8 · Postby **ColoradoTR8** » 25 Mar 2011 15:07

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Craig C

They still look hot with 17's!

Craig
<hr height="1" noshade id="quote"></blockquote id="quote">

That they do!

Shawn

Beans · Postby **Beans** » 26 Mar 2011 00:52

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Craig C

... I think it looks fantastic in the 17's ... <hr height="1" noshade id="quote"></blockquote id="quote">
Beauty is in the eye of the beholder, but sometimes a visit to Specsavers might help [:p]

<center>

1980 TR7 DHC (my first car, now restored and back on the road)
1981 TR7 FHC Sprint (better known as 't Kreng)
[url="http://www.tr7beans.blogspot.com/"]My Weblog[/url]</center>

FI Spyder · Postby **FI Spyder** » 26 Mar 2011 02:03

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Craig C

Come on guys, my daily driver is a Holden Sportwagon with 245/45/18s as standard. Bone-shaking? I think not...
<hr height="1" noshade id="quote"></blockquote id="quote">

They may work on the Holden with it's modern suspension that's designed for them but will be bone shaking on the TR7. A friend has 60 series on his TR7 and it's bone shaking. The lower the series the higher the pressure the more the road is transfered through. The TR7 was designed for 70 series tires and low pressures. The feel of the road is sensitive to tire pressure. I personally prefer a higher tire pressure but where as my Toyota's 13" and Integra's 14"/15" can handle it the TR7 you can feel every little pebble. It's fine for highway speeds but a bit much on 60kmh country lanes. Wish I had variable pressure adjust. Same with shocks. Koni makes all three basic designs each with different characteristics and which is used (recommended) for which car depends on the design of the suspension.

The 240Z doesn't look too bad with them but then it's just another rice rocket for the drifter set.

TR7 Spider - 1978 Spitfire - 1976 Spitfire - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra - Yellow TCT

Craig C · Postby **Craig C** » 26 Mar 2011 10:29

My Tr7V8 currently has 195/50/15's (34 psi) at the front with 200lb TT springs, hardened rubber and polyurethane bushes. I reckon I'll survive the 45 series rubber...

"Ricer"? Puh-lease. And what's wrong with drifting? Check out a Ken Block vid on Youtube and tell me that's not one of the most amazing things done with a car. Ever.

http://www.youtube.com/watch?v=4TshFWSsrn8

Warning: traction is ocasionally lost...

Craig

ColoradoTR8 · Postby **ColoradoTR8** » 26 Mar 2011 13:04

I have 205/45R16's oon my TR8, with stiffer springs, larger swaybars and poly bushes in most locations. The ride is no more stiff than with the 205/60R13's that I replaced, I can feel a bit more through the steering wheel but not the seat. The wedges suspension is a much more modern long travel design of suspension. Put a 45 series tire on a TR2-6 type of suspension and you would feel a much larger difference that would be very bone jarring. Especially if they have stiffer springs and bushings. I never wanted to go blow a 65 series tire on my TR6 with its fast road suspension. I could already feel a dime under the tire through the steering wheel, that was good enough.

The grip and feel difference of the taller wheel/shorter sidewall gives the car a much improved sporty feel on the backroads and is still smooth on the highways/interstates (as long as those roads aren't in serious need of repair).

My car already had the 205/60R13's when I bought it, nothing special, just an all season radial. The 205/45R16's are Kumho Ecsta's with a much more high performance tread pattern, yet they are still quiet and run at nearly the same pressures as the 205/60R13's. I think I am currenlty running 2psi higher than the smaller tires.

Just my experience, some have more sensitive backsides.

Shawn

Marko · Postby **Marko** » 01 Apr 2011 23:51

hey,

it took me a while since im up to my head in work.

So where to start.

vehicle mass , i took the max alowed axle load of an tr8 thats 1460 kg total. Car wont weigh more than that anyway.

Stock pcd is 95.25 , stock tire dimension is 185/70 R13, giving the leverage of the tire traction 6,185 ( tire radius/half of the pcd ).

Loading the whole vehicle on 1 wheel (impossible event), with decent tire will give 22138N per wheel bolt.

Your pcd is 114.3 with 245/40 R17 tires , results in 5.492 leverage of the tire traction.

The idea was to build up the weld on the back of the hub

and that lower leverage results in lower stress on the hub

This simulation was done with a big exageration in way the hub is loaded since all the forces are acting trough the bolt holes only.
That would be equal of wheel bolts not being torqued at all.

Properly torqed wheels transmit forces trough the friction between the wheel flange and hub face, and the center ring(center hole) on the hub (wheel). so the actual stress will be even lower.

The only load that i checked is braking , since that is the single bigges force that acts in suspension. If it holds that , it holds everything else.

DNK · Postby **DNK** » 02 Apr 2011 00:32

[?]
Ah , that's what I figured .
Yea sure.Way over my head Marko. Nice job

Don
"No More Cars For You"
71 TR6- Perpetual remodel
80 TR7 V8 Kick in the pants

Bendder · Postby **Bendder** » 02 Apr 2011 01:48

Marko,

I think you possibly have a better understanding of Math than I do!

Mark
1977 TR7 FHC
1978 TR7 FHC
1980 TR7 DHC
1980 Rover SD1 4.0L

Marko · Postby **Marko** » 02 Apr 2011 12:02

the bigger wheels dont increase the suspension forces by that much as some "educated" people like to preach. Because you dont double the wheel radius, you just increase it by some percent.

You know what, those Rota RB's are starting to look nicer and nicer for a 7 every time i see them. Set of 4 15"X7 costs 568 euro's here.

DNK · Postby **DNK** » 02 Apr 2011 16:58

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Marko

...You know what, those Rota RB's are starting to look nicer and nicer for a 7 every time i see them. Set of 4 15"X7 costs 568 euro's here.
<hr height="1" noshade id="quote"></blockquote id="quote">

Marko, I have the VTO's in that size and I am kicking myself for not going 8's in the rear.
Think hard about that

Don
"No More Cars For You"
71 TR6- Perpetual remodel
80 TR7 V8 Kick in the pants

Reddragon · Postby **Reddragon** » 02 Apr 2011 21:06

Marko

Have you taken in the consideration of what welding the extra material on to the hub would do?

The heat soak of the welding may cause stress fagitue to the area of the outer edge. Then drilling for 114.5 mm studs puts these very close to the edge even with the extra backing as shown.

I have been thinking about this, but using only 4x100 mm, an am still very concerned that there is too little material there to work with.

Canley Classic's makes an aluminum hub for the GT-6 and Spitfire that they will sell with out stud holes. Even though it looks strouter, I don't think that this will work with our struts.

Maybe some one over there can look into this application for the rest of us? Can some one call them to see if their hub would work on the Tr7 wheel shaft? At 79 Pounds plus the cost to drill to 4X 100 mm, if this would fit our struts would be cheap, safe fix to different wheels for these cars.

Dale
1974 TR6
1977 TR7 FHC

Craig C · Postby **Craig C** » 02 Apr 2011 21:24

Thanks Marko, I appreciate the work you have put in.

Very timely as I have just put the deposit down for the wheels and tyres (AUD$990 for the set of alloys ($1180 delivered to Alice Springs from QLD). The wheels are due in the country on the 8th so I should have some piccies to post by Easter. Due to the fact that "well-priced" (a euphemism for "cheap" [;)]) tyres are extremely hard to come by in the pair of sizes I was after (255/45/17 in particular being the very unusual size), the rears will now be 275/40/17s ($146 each). No change to the front at 245/40/17 ($127 each). The tyres chosen (Federal SS-555) are apparently good in the dry, not so flash in the wet. I live in Alice Springs, so who cares about wet weather performance!

Now back to your work: The stress graphic appears to show that the biggest load is at the front of the hub; does this indicate that building up the thickness of the rear face is not required? Or if it is, is there a min thickness required?

Craig

Marko · Postby **Marko** » 03 Apr 2011 12:22

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Craig C

The stress graphic appears to show that the biggest load is at the front of the hub;
<hr height="1" noshade id="quote"></blockquote id="quote">

You expressed the concern of wheels fallin off due to to bolts shearing off.

The pictures just show that increasing the pcd lowers the stress on the bolt mounting holes.That stress is equal to braking with a loose wheel bolts and trying to shear them off by brake torque. Those two FEM pictures just represent that , first with standard pcd , and the second fem picture with modified. The second picture shows how was the material built up.

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Craig C

does this indicate that building up the thickness of the rear face is not required?

Or if it is, is there a min thickness required?
<hr height="1" noshade id="quote"></blockquote id="quote">

It is requred , because without it the half of the wheel stud countersink will be free in air, it wont rest on metal.
I would just make it flush with the stock back side of the flange (you practicaly remove the chamfer compleatly). That way you have full thickness of the hub , just like with the stock PCD.

Reddragon it just needs to be welded correctly and machined afterwards.
TIG, preheating, nickel based filler rod for castings works great,and work at a pace, you dont need to torture the part with 300 amps just to finish the job quicker.

Anonymous

Changing wheel stud PCD

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