LocostUSA.com

Learning how to build Lotus Seven replicas...together!
It is currently November 19, 2017, 11:51 pm

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 13 posts ] 
Author Message
PostPosted: February 5, 2015, 10:45 pm 
Offline

Joined: February 5, 2015, 10:12 pm
Posts: 3
Hey guys. I'm a new member of the forum, although I've been lurking for a while as I design my own locost-ish project. Here's a high level overview of what I'm looking to do, to frame my question:

- Single seat, mid-engine configuration
- Steel tube frame
- 1300cc bike engine (likely 'busa or ZX)
- Chain drive
- 700lb target vehicle weight
- SLA/Dual a-arm/wishbone suspension front and rear
- Maximum use of junkyard/standard OEM parts
- Minimum "complex fabrication" (anything beyond tubing work and basic fabrication, e.g. no CNC uprights or custom diff cases)

I've been making good progress on the overall design and have been able to find general solutions for most things, but where I'm hung up is the differential/cv axle/rear upright system. I've decided that I will try to splurge on a Quaife QDF7ZR http://www.quaifeamerica.com/qdf7zr-0.html differential, likely making it the second most expensive part of the whole car after the engine. The differential is described as using "Escort/Fiesta shafts," and after much back-and-forth with Quaife about what this actually means, I've determined that the output from that diff is 23 splines in a 28mm bore, the same as Ford used on the "IB5" FWD trans. Apparently these axles are plentiful in the UK as they were used on the UK Escorts and Fiestas, but the only US cars that used this "inboard spline" are 2000-2004 Ford Focuses with the 2.0L SPI engine and manual trans (code IB5).

So that's all well and good - I could use the whole Focus front drivetrain as my rear setup. No big deal, just an easy toe-rod connection to the frame. The problems with this are twofold: the Focus used an idiotic 4x108 bolt pattern, ruling out all the nice lightweight wheels available in 4x100. Second, the Focus used a strut front end, making the uprights difficult to adapt to an a-arm setup.

So now I'm stuck. Custom CVs are far, far too expensive (from what I've seen). Quaife sells stub shafts for a "100mm Lobro" joint, but they're another $300 on top of the diff cost, and then I still need some kind of axles. And the Focus hubs are press-on, so I can't just bolt them on a custom or compatible upright. Machining an upright to fit the press on hub isn't an option I'm considering. Ideally I'll run some OEM upright with a 4x100 bolt pattern that is readily adapted to a-arm connection. I'm not that concerned about geometry (KPI etc.) given that it's just the rear.

Since you all have a wealth of knowledge on parts compatibility and out-of-the-box solutions, I'm interested to hear what you have to say. A few general questions leap to mind:

- Is there a viable alternative to the Quaife chain-drive diff?
- Are there other US-market CV axles known to be compatible with the QDF7ZR?
- Can I affordably ship over some junkyard UK axles?
- Can I piece together custom shafts from Focus inner joints and some other outer joint?
- Can I just duct tape a sawed off broom handle between the diff and the hubs and go easy on the throttle?

Any wisdom is appreciated!

Mike


Top
 Profile  
Reply with quote  
PostPosted: February 6, 2015, 1:15 am 
Offline
Toyotaphobe
User avatar

Joined: April 5, 2008, 2:25 am
Posts: 4498
Location: Fort Worth, Texas
I'll try to get pics and post tomorrow, but I have a complete FSAE set up with uprights, axles, chain drive LSD Civic diff and axle brake that I'm going to get rid of.

I just got rid of the bike that was the possible donor so now I definitely don't need them. I bought them off a forum member a couple of years ago "just in case". The price will be right.

_________________
mobilito ergo sum
I drive therefore I am

I can explain it to you,
but I can't understand it for you.


Top
 Profile  
Reply with quote  
PostPosted: February 6, 2015, 3:34 am 
Offline

Joined: June 6, 2012, 8:17 am
Posts: 145
Location: Montreal, Quebec
Formula Locost wrote:

So that's all well and good - I could use the whole Focus front drivetrain as my rear setup. No big deal, just an easy toe-rod connection to the frame. The problems with this are twofold: the Focus used an idiotic 4x108 bolt pattern, ruling out all the nice lightweight wheels available in 4x100. Second, the Focus used a strut front end, making the uprights difficult to adapt to an a-arm setup.




Not all that difficult to do. Here's my mustang spindle that were used with strut u[prights adapted for A-arms.

Attachment:
DSC_0033.JPG
DSC_0033.JPG [ 263.81 KiB | Viewed 2666 times ]

Attachment:
DSC_0036.JPG
DSC_0036.JPG [ 113.23 KiB | Viewed 2666 times ]

Attachment:
DSC_0034.JPG
DSC_0034.JPG [ 61.72 KiB | Viewed 2666 times ]


Top
 Profile  
Reply with quote  
PostPosted: February 6, 2015, 9:01 am 
Offline
User avatar

Joined: October 21, 2010, 2:01 am
Posts: 140
Location: Portland Oregon
I have found one of the most robust and economical solution to axles are VW stuff. I bought brand new German made axles with inner CV's for $97.00 each! The quaife diff below is an excellent piece of kit. They accept VW stub shafts, the are grease lubed and easy to mount. Look at my build I made eccentric chain adjusters and they work awesome. Some much cleaner and stronger than a cantilever system with jack screws! IMO

http://shop.quaife.co.uk/catalogsearch/ ... b_type=&q=

Also not to burst your bubble, but 700 lbs is a bit optimistic if you plan to use a Busa. My concern is your chassis strength if you go too light. Mine is 1.25" Dia .035 wall 4130.

Good luck with the build and keep the pics coming.
Cheers
Linz


Top
 Profile  
Reply with quote  
PostPosted: February 6, 2015, 9:34 am 
Offline
User avatar

Joined: July 17, 2008, 9:11 am
Posts: 4360
Location: West Chicago,IL
You could cut and shorten the half-shafts yourself. It is frowned upon by many, but I've done it and have several years of driving with them. No problems yet. Like my rotary engine, the bike engine won't make big Torque, only around 100lb-ft in stock form, so it is not a big amount of stress comparatively. You should be safe. Those shortened shaft failures that I have read about were usually on big V8's

viewtopic.php?f=35&t=4145&start=30

Likewise, adapting strut components for use in double wishbone systems has been done many times here. That should not be a game breaker.

Using automotive parts designed for vehicles 3-4 times the weight may not be the best way to accomplish a goal of 700#.

What is your purpose? Will this be a track-only type car?

_________________
Chuck.

“Any suspension will work if you don’t let it.” - Colin Chapman

My RX7 powered Locost is now for sale http://www.locostusa.com/forums/viewtopic.php?f=40&t=18460

or visit my Cushman Truckster resurrection log: over HERE


Top
 Profile  
Reply with quote  
PostPosted: February 6, 2015, 10:38 am 
Offline

Joined: February 5, 2015, 10:12 pm
Posts: 3
Thanks all for the input. IT probably would have been better to say "light weight is a high priority, but lower than cost" than giving an actual weight target. 700lbs is right on the edge of what I estimate to be possible, but I have about 15% confidence in hitting that number. Generally, I'm trying to do good up front design and smart component selection as a way to affordably reduce weight.

I also forgot to mention that I'm not considering open diff options, as straight line performance is an important factor to me. I'd sooner go with a spool setup than an open diff.

carguy123 wrote:
I'll try to get pics and post tomorrow, but I have a complete FSAE set up with uprights, axles, chain drive LSD Civic diff and axle brake that I'm going to get rid of.


Keep me in the loop!

bevins wrote:
Not all that difficult to do. Here's my mustang spindle that were used with strut uprights adapted for A-arms.


Nothing against your solution, but I'm not at all comfortable with welding (or even bolting) together my uprights unless they have been specifically designed from scratch to minimize stress on the welds. One solution I considered was some thick-wall tube the same OD as the strut , clamped into place and somehow providing mounting for a spherical... but it's a complex and heavy solution where, IMO, neither trait is desired.

kiwimanz wrote:
I have found one of the most robust and economical solution to axles are VW stuff. I bought brand new German made axles with inner CV's for $97.00 each! The quaife diff below is an excellent piece of kit. They accept VW stub shafts, the are grease lubed and easy to mount. Look at my build I made eccentric chain adjusters and they work awesome. Some much cleaner and stronger than a cantilever system with jack screws! IMO

http://shop.quaife.co.uk/catalogsearch/ ... b_type=&q=


Linz - your build is impressive, definitely a level above what I'm looking to do. Now I'm confused on the Quaife diff, though. Their US customer service confidently assured me that the chain drive, grease filled diff came only in the Ford axles I describe. I'll have to follow up to ask about VW pattern stuff.

rx7locost wrote:
You could cut and shorten the half-shafts yourself. It is frowned upon by many, but I've done it and have several years of driving with them. No problems yet.


So I could use the inner half of the Focus axles and mate them via tube sleeve and weld to the outer half of the axles of my choice... not a bad idea. It would be nice to be able to determine the width of my frame vs. having axle availability decide it for me. The sticking point could be finding axles with identical OD shafts so I could use continuous piece of tube to mate them. Hmmm.

rx7locost wrote:
What is your purpose? Will this be a track-only type car?


That's a deep question. Primarily it's a fun engineering/build exercise that will ultimately yield a streetable, track-worthy car with few compromises for comfort and relatively peerless performance. It may get tracked and autocrossed, but the heaviest use will be on the street. I'm fairly young and in decent shape, so a harsh ride and lots of NVH are not a big concern. Ultimately it's about me designing, building, and driving a car for me.


Top
 Profile  
Reply with quote  
PostPosted: February 6, 2015, 11:02 am 
Offline
User avatar

Joined: July 17, 2008, 9:11 am
Posts: 4360
Location: West Chicago,IL
Quote:
So I could use the inner half of the Focus axles and mate them via tube sleeve and weld to the outer half of the axles of my choice... not a bad idea. It would be nice to be able to determine the width of my frame vs. having axle availability decide it for me. The sticking point could be finding axles with identical OD shafts so I could use continuous piece of tube to mate them. Hmmm.


This^, or your tube splice could be sized for the smaller ID (i.e. thicker wall, and then bored out ~1/2 way for the larger dia shaft. This would allow for 2 different shaft diameters. I may not have thought that one through totally, but I think it should work. It would make the aligning of the 2 shaft axis a bit more difficult, but could be done.

_________________
Chuck.

“Any suspension will work if you don’t let it.” - Colin Chapman

My RX7 powered Locost is now for sale http://www.locostusa.com/forums/viewtopic.php?f=40&t=18460

or visit my Cushman Truckster resurrection log: over HERE


Top
 Profile  
Reply with quote  
PostPosted: February 6, 2015, 11:59 am 
Offline

Joined: October 19, 2009, 9:36 pm
Posts: 2004
Location: meadview arizona
to join two shafts of different diameters try this method.

1. buy a piece of cds tube with an inside diameter of the smaller shaft and an outside diameter larger than the larger shaft.

2. bore the larger shaft with a hole about half the dia of the small shaft and about 1" deep.

3. turn down the small shaft to press fit in the hole you just bored but leaving a gap.

4.fill the gap with weld so that most of the weld is in the gap then turn off the weld and the larger dia of the shaft down to the small shaft dia 3" past the join.

5. cut your tube to about 6" long and drill a hole about 1/4" dia in the middle of the tube and two more about an inch from each ends, countersink the holes then bevel the ends of the tube.

6. slide tube over the join until you see the original joint in the middle hole and plug weld in the hole, and in the other two holes.

7. now fillet weld at each end.

8. at no time quench the welded parts in this process as imbrittlement may occur due to the unknown composition of the original shafts and heat treatment the may have been subjected to when manufactured.

it might work.

_________________
this story shall the good man teach his son,
and chrispin chrispian shall ne'er go by,
from this day to the end of the world.
but we in it shall be remembered.


Top
 Profile  
Reply with quote  
PostPosted: February 6, 2015, 1:33 pm 
Offline

Joined: February 5, 2015, 10:12 pm
Posts: 3
rx7locost wrote:
This^, or your tube splice could be sized for the smaller ID (i.e. thicker wall, and then bored out ~1/2 way for the larger dia shaft.)


Maybe what I could do is buy two pieces of tube, one with the ID of the smaller axle and the OD of the larger axle and one with the ID of the larger axle. Tube 1 gets welded to the smaller axle to bring it up to the OD of the larger axle, and then tube 2 is welded on over the whole shebang. Might be tricky to find tube 1 in the right size, but with good choices of CVs it could be possible. More research needed, although this is still a Plan B option to just using something off the shelf.

john hennessy wrote:
to join two shafts of different diameters try this method.


That's a lot of machining for a guy with no lathe! But I agree, it could work...

Formula Locost wrote:
Now I'm confused on the Quaife diff, though. Their US customer service confidently assured me that the chain drive, grease filled diff came only in the Ford axles I describe. I'll have to follow up to ask about VW pattern stuff.


Just confirmed with Quaife - they used to make the chain-drive diffs in other patterns, but now they only produce the Ford-based models. Dang.


Top
 Profile  
Reply with quote  
PostPosted: February 6, 2015, 3:09 pm 
Offline
Toyotaphobe
User avatar

Joined: April 5, 2008, 2:25 am
Posts: 4498
Location: Fort Worth, Texas
Here is the thread on the FSAE bits I have for sale.

http://www.locostusa.com/forums/viewtopic.php?f=40&t=17108

_________________
mobilito ergo sum
I drive therefore I am

I can explain it to you,
but I can't understand it for you.


Top
 Profile  
Reply with quote  
PostPosted: December 28, 2016, 6:08 pm 
Offline

Joined: December 28, 2016, 5:23 pm
Posts: 9
kiwimanz wrote:
I have found one of the most robust and economical solution to axles are VW stuff. I bought brand new German made axles with inner CV's for $97.00 each! The quaife diff below is an excellent piece of kit. They accept VW stub shafts, the are grease lubed and easy to mount. Look at my build I made eccentric chain adjusters and they work awesome. Some much cleaner and stronger than a cantilever system with jack screws! IMO

http://shop.quaife.co.uk/catalogsearch/ ... b_type=&q=

Also not to burst your bubble, but 700 lbs is a bit optimistic if you plan to use a Busa. My concern is your chassis strength if you go too light. Mine is 1.25" Dia .035 wall 4130.

Good luck with the build and keep the pics coming.
Cheers
Linz

wow .035" wall? no issues? that seems almost scary, i was planning on using .065.


Top
 Profile  
Reply with quote  
PostPosted: December 29, 2016, 5:34 pm 
Offline
Always Moore!
User avatar

Joined: November 9, 2007, 3:40 pm
Posts: 3888
Location: Fort Worth, TX
We used 0.035" wall on FSAE cars all of the time. Don't plan on using it for anything that's part of a crash structure and you'll be fine.

_________________
-Andrew
Build Log
Youtube


Top
 Profile  
Reply with quote  
PostPosted: October 6, 2017, 10:18 pm 
Offline

Joined: October 6, 2017, 9:25 pm
Posts: 5
Check out dwarfcarracing.com. Lots of manufactures of front spindles uprights etc. Peter D is one which makes a good spindle for dwarf cars, legends and modifieds.


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 13 posts ] 

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 4 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
POWERED_BY