LocostUSA.com

Learning how to build Lotus Seven replicas...together!
It is currently April 10, 2020, 6:08 am

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 11 posts ] 
Author Message
PostPosted: March 25, 2020, 2:32 am 
Offline

Joined: March 18, 2008, 10:25 pm
Posts: 280
Location: Wasilla, AK
I'm building a 442 with mustang ii drop spindles. I finally designed and made my control arms and tacked on the brackets. I now have to decide what rack and pinion to use. I can weld aluminum or steel though the aluminum ones would likely be cast. I want something with a decently fast ratio and don't mind converting it from power steering to manual. Any recommendations?


Top
 Profile  
Reply with quote  
PostPosted: March 25, 2020, 3:07 am 
Offline
User avatar

Joined: April 22, 2010, 4:43 pm
Posts: 357
Location: Livermore, Calif.
I would suggest a shortened Mazda Miata rack. They are plentiful but most come as power steering racks which can be easily shortened and de-powered. There's a lot of instructions in the archives that discuss this modification. I've attached a couple of pictures showing the rack in the "before" and "after" configuration.

I'm sure you could find other racks out there that could be purchased and would not require shortening.

Roy


Attachments:
1010200001.JPG
1010200001.JPG [ 544.97 KiB | Viewed 300 times ]
Mark up 2.jpg
Mark up 2.jpg [ 227.33 KiB | Viewed 300 times ]
2014_0923_short_rack0001.JPG
2014_0923_short_rack0001.JPG [ 1.53 MiB | Viewed 300 times ]

_________________
Build log http://www.locostusa.com/forums/viewtopic.php?t=16510
Top
 Profile  
Reply with quote  
PostPosted: March 25, 2020, 5:32 am 
Offline
User avatar

Joined: June 20, 2019, 12:34 pm
Posts: 211
I would suggest you figure out what width rack you need for a start. Find the axis where your upper & lower pivots on your control arms intersect. That is where your inner tie rod pivot needs to be located for your rack. You then have the width you need for the rack itself. You can shorten or lengthen the tie rods to reach the uprights. This will set it up to reduce bump steer.

If you are using a 442 plan your width is fairly wide, You may want to look at the Mustang II manual rack. They are available new for about $150.

Thom


Top
 Profile  
Reply with quote  
PostPosted: March 25, 2020, 9:24 am 
Offline
User avatar

Joined: January 2, 2009, 1:45 pm
Posts: 1240
Location: Halifax, Nova Scotia
I included track width in my suspension design iterations and eventually converged on a design that allowed me to use a stock MGB rack. There are a number of options for racks which offer the possibility of using an unmodified rack, IF you include those considerations in suspension design and A-arm mount width.

_________________
Warren
Isuzu Pickup/SR20DE, +401 COLD frame
Build Log: viewtopic.php?f=35&t=11601


Top
 Profile  
Reply with quote  
PostPosted: March 25, 2020, 10:36 am 
Offline
User avatar

Joined: January 11, 2017, 11:06 pm
Posts: 125
Location: Alberta
Unisteer does custom R&Ps for what I considered to be a very good price. I got custom made tie rods at the same time, so I was able to attain optimal geometry pretty easily. I selected the highest ratio of 1.5" linear travel per rotation and it worked well with my modified SN95 spindles (steering links somewhat shortened for an even faster effective ratio).


Top
 Profile  
Reply with quote  
PostPosted: March 25, 2020, 2:15 pm 
Offline
User avatar

Joined: December 4, 2010, 1:53 pm
Posts: 65
Location: Edmonton, Alberta, Canada
I used an early MGB rack, which I shortened by 4". My frame is a narrow "book" frame. If yours is wider, you may not need to shorten an MGB rack to make it work. Shortening is really straight forward, cut and weld the tube, and shorten the rack and re-thread the end.
One advantage, you don't need to de-power it. A word of caution, don't used a later "rubber bumper" rack, as they are slower, more turns lock to lock.
Many Cobra kit cars use a knock off of this rack by Flaming River, so that may be an option if you don't want to use a used rack.
https://www.flamingriver.com/index.php/ ... 009/FR1512


Attachments:
20160715_165719-small.jpg
20160715_165719-small.jpg [ 118.75 KiB | Viewed 258 times ]

_________________
book 4AGE build, W58 transmission, Corolla GTS live axle
Top
 Profile  
Reply with quote  
PostPosted: March 25, 2020, 3:07 pm 
Offline
User avatar

Joined: July 17, 2008, 9:11 am
Posts: 5363
Location: West Chicago,IL
It may be a bit of work to shorten a rack, but you can make it exactly the length you want without trying to estimate what model car's rack might be suitable for you particular build. BTW, I shortened and depowered my RX7 rack. It is much like the Miata rack.

_________________
Chuck.

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

Visit my ongoing MGB Rustoration log: over HERE

Or my Wankel powered Locost log : over HERE


Top
 Profile  
Reply with quote  
PostPosted: March 26, 2020, 1:08 am 
Offline

Joined: March 18, 2008, 10:25 pm
Posts: 280
Location: Wasilla, AK
I'm going to check for a miata rack at the wrecker yards when the quarantine stuff ends. Research showed an integra has a fast steering ratio as well. Rx7 is good info. I didn't want to use a mustang ii manual rack as the ratio is slow and 4 turns lock to lock. Keep recommendations coming, thanks guys.


Top
 Profile  
Reply with quote  
PostPosted: March 26, 2020, 4:31 am 
Offline
User avatar

Joined: December 24, 2007, 5:11 am
Posts: 991
Location: Seattle area
I am using a shortened Miata de-powered rack. My steering isn't to my satisfaction and I'm considering changing the rack to this. Price seems right for a new part.

http://www.victoriabritish.com/features/sg/SGSTR.htm

Good luck.

_________________
Larry in Seattle


Top
 Profile  
Reply with quote  
PostPosted: March 26, 2020, 10:14 am 
Offline
User avatar

Joined: December 4, 2010, 1:53 pm
Posts: 65
Location: Edmonton, Alberta, Canada
That Spitfire rack looks like a good route to go. The thing I like about the early MGB rack is that is is 2.5 turns lock to lock. I was going to use a Subaru rack until I realized that it was 3.5 turns lock to lock, way too slow.

_________________
book 4AGE build, W58 transmission, Corolla GTS live axle


Top
 Profile  
Reply with quote  
PostPosted: March 26, 2020, 10:57 am 
Offline
User avatar

Joined: July 17, 2008, 9:11 am
Posts: 5363
Location: West Chicago,IL
Turns lock to lock alone is not a good way to evaluate racks IMO. A better way is to include just how much travel the rack makes per turn of the steering wheel. Also consider the length of the steering arms on the uprights, especially if one is mixing components, as they all play a part in determining how much a given steering wheel movement makes the front wheels move.


All that, for steering motion plus the obvious bump steer considerations.

_________________
Chuck.

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

Visit my ongoing MGB Rustoration log: over HERE

Or my Wankel powered Locost log : over HERE


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 11 posts ] 

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 2 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