QA1 R157-170 Four Link Kit Installation Guide

: August 28, 2024
: QA1

Table of Contents

QA1 R157-170 Four Link Kit
Specifications
FAQs
INSTALLATION INSTRUCTIONS
Installation
Shock Valving Adjustments
DISCLAIMER / WARRANTY •
CONTACT INFORMATION
Read User Manual Online (PDF format)
Download This Manual (PDF format)

QA1 R157-170 Four Link Kit

Specifications

Product: QA1 Rear Suspension for 1970-1981 GM F-Body
Model Numbers: R157-170, R257-170, R357-170
Technical Support Line: 952-985-5675
Email: sales@QA1.net

FAQs

Q: What additional components can be used with this rear suspension?

A: Consider upgrading with the QA1 Rear Anti-Roll Bar (p/n 52828) and Subframe connectors (p/n 52094 for ’70-’74 or p/n 52095 for ’75-’81).

Q: Is welding required for installation?

A: Yes, welding is necessary near the fuel tank area and fuel lines on the driver-side frame rail. Ensure the fuel tank is nearly empty before starting.

INSTALLATION INSTRUCTIONS

QA1 P/N R157-170, R257-170,
R357-170 Rear Suspension
1970-1981 GM F-Body

TOOLS AND SUPPLIES REQUIRED

Floor Jack
Two Jack Stands
Mig Welder capable of ¼” penetration
SAE Wrench Set
Anti-seize
Angle Grinder
Ratchet & Socket Set
Torque Wrench
Tire Chocks
Four Large C-Clamps
Digital Angle Finder

Note: This installation requires welding near the fuel tank area and fuel lines on the driver-side frame rail. Ensure that the fuel tank is near empty before beginning as the tank will need to be removed.
Consider upgrading this suspension with the QA1 Rear Anti-Roll Bar (p/n 52828) and Subframe connectors (p/n 52094 for ’70-’74 or p/n 52095 for ’75-’81)

Removal

Measure the beginning ride height of the car from the fender down through the center of the wheel to establish the original ride height.
Measure the front to rear wheelbase from the center of the front hub to the center of the rear hub as a base reference.
Disconnect the vehicle battery as welding to the frame will be necessary for installation.
Raise the rear of the car and support it at the frame rail with jack stands on a stable surface.
Remove the rear exhaust section. Alternative exhaust routing may be required.
Support the axle before removing the upper shock connection. The axle may be hanging from the shocks and drop further during this step without support.
Mark the driveshaft phasing at the pinion and remove the driveshaft from the car.
Remove the brake line connection near the driver’s side of the axle.
Remove the rear sway bar (if equipped)
Remove the fuel tank and any open lines near the welding area.
Loosen the front and rear leaf spring mounts. Do Not Remove At This Time.
Lightly support the axle using a jack or by setting the car slightly on the ground to contain the energy of the leaf springs.
Remove the front and rear leaf spring hardware and remove the axle from the car.
Remove the pinion snubber. (Figure 1)
On ’74-’81 cars, remove the exhaust hanger brackets from both sides of the rear floor pan. (Figure 2)
- If Using A Vehicle Lift-
- Re-check the vehicle weight balance now that the heavy axle has been removed. Reposition the lift arms or use a pole jack at the front of the vehicle for stability.
Remove the front leaf spring mounts from the leaf springs. Mark the leaf spring mounts as they are right/left specific. If QA1 subframe connectors are being installed, the leaf spring mounts can be discarded.
Remove the driver and passenger side bump stops. The rear bolt hole of the bump stops will be used as a marker for the crossmember placement. Draw a line through the center of the rear bolt hole onto the bottom side of the frame before reinstalling the bump stops in their original location. (Figure 3)

Installation

Note: This installation process will require the suspension to be mocked up at ride height before the axle is removed for welding the tabs to the axle and the cross-member welded into the car. All listed torque values for the hardware will be used upon final installation of the suspension.

Identify the right/left axle mounts. (Figure 4, #3 & #4)
Drill the axle u-bolt holes to 1/2″ before bolting the axle brackets to the axle using included u-bolts and hardware. Evenly torque to 50 lb. ft. (Figures 5,6,7)
Remove the mounts holding the fuel lines to the frame rail. The fuel lines may remain in place while the cross-member is fitted to the car but will need to be pushed up out of the way as much as possible before welding. Fuel lines should not be opened anywhere near the frame rail unless they will be fully removed during welding.
Place the QA1 crossmember in place using clamps. The center of the crossmember is adjustable to adjust for the narrower frame width of earlier cars. Loosen the jam nuts and adjust the hex as needed to fit the outer flanges against the inner frame rails. Tighten the jam nuts after adjusting. (Figure 8)
Place a straight edge on the bottom frame rail and measure up to the bottom of the front crossmember flange. Measuring back from the rearmost bump stop mounting hole 2 3/16” ±1/4, which will set the front to rear position on both sides. (Figure 9) The height of the front of the crossmember can be verified by measuring up from the bottom of the frame rail (using a straight edge) to the bottom of the weld plate. The upper crossmember flange should measure 2-3/16” from the marked line at the bump stop hole. (Figure 10) This should be the location of the lower front flange on both sides of the crossmember.

  *  **NOTE:** The rear upper crossmember flanges should sit flat against the bottom of the frame rail. The rear seat floor pan is not the same from left to right causing the crossmember to mount closer to the firewall on the left than the right.
4. Mark the areas of the frame where the crossmember flanges will be welded.
5. Remove the crossmember and sand the marked frame rail areas to bare metal. Weld-through primer can be applied to the frame rails and the frame-facing flange faces to prevent future corrosion.
6. Reinstall the crossmember to the correct position using the measurements for the flange locations in Step 3.
7. Remove all items from the trunk and leave the trunk lid open during welding. QA1 recommends keeping pressurized air close by to eliminate hot spots during welding which could lead to a fire.
8. Using a welder capable of 1/4” penetration, plug weld all holes in the front flanges and the flange edges of the rear flanges. (Figure 11) Alternate sides during welding to prevent overheating/warping of the flanges or frame rails. Using compressed air to cool each weld and eliminate the chance of inner frame rail fires is highly recommended.
9. Prime and paint the finish-welded flanges of the crossmember.
10. Verify the QA1 lower trailing arm length is 25-1/8” center to center on the mounting bolt holes. The adjustment range after installation is 24-1/2” to 25-7/8” The trailing arms are not right/left specific but will need to be mounted so that the rear of the trailing arms are bent inboard. (Figure 12)
11. Remove the factory u-nuts from the leaf spring mount location and replace them with the included u-nuts included with the suspension.
12. Using the brackets from the QA1 subframe connecter kit or the OE leaf spring mounts, bolt the fixed bushing end of the QA1 lower trailing arms to the mounts with the rear portion of the trailing arms curved inboard at the rear. (Figure 13) using one 1.3” wide black anodized spacer on the outboard side of the mount. This connection can only be accomplished with the leaf mounts/subframe connector removed from the car. Secure using 1/2″x 5” bolt with two washers and one nyloc nut per side with the bolt head on the inboard side of the mount. (Figure 13) This connection should be final torqued to 75 lb. ft. before reinstalling the subframe connector/leaf spring mounts to the car.
13. With the lower trailing arm attached to the factory front leaf spring mounts, reinstall the front leaf spring mounts onto the vehicle using the included new J-nuts and 3/8” hardware. (Figure 14) Torque to 30 lb. ft.
14. Verify the QA1 upper trailing arms are 9.75” center to center on the mounting bolts. The adjustment range after installation is 9-1/4” to 10-1/4”.
15. With one SG88 spacer on each side of the upper trailing arms, install the upper trailing arm into the inner mounting tabs at the front of the crossmember. Secure using 1/2″x 3.25” hardware with two washers and one nyloc nut per connection. (Figure  Torque to 50 lb. ft.
16. Identify the left/right weld-in mounts for the upper trailing arm-to-axle connection and install the red anodized upper trailing arms into the upper hole with one SG12-88 spacer on each side of the rod end. (Figure 15) Secure using 1/2″x 3.25” hardware with two washers and one nyloc nut per connection. The upper trailing arms should now be hanging from the crossmember with weld-in brackets in preparation for the axle mock-up. (Figure 16)
17. Mount the coil-over shocks (without springs for mock-up) onto the rear crossmember mounts using 1/2″ x 2-3/4” hardware with two washers and one nyloc nut for the upper connection.
18. Roll the axle into place and support the pinion with a jack stand so that the axle does not roll.
19. With one SG12-88 high misalignment spacer on each side of the rod end, connect the lower trailing arms to the upper hole of the axle mounts using 1/2″ x 3.25” hardware, with two washers and one nyloc nut. (Figure 17) Torque to 75 lb. ft.
20. With the upper trailing arms swung above the axle, mock the axle up so that it is centered under the vehicle with an axle to bottom of frame measurement of 4-3/4”.(Figure 18)
21. With the axle height set at 4.75”, adjust the pinion angle to 0 degrees relative to the drive line.
22. Lift the upper trailing arms and clean the axle tube to bare metal where the mounts will be welded.
23. Double-check all clearances and measurements before continuing.
24. Install the 3D-printed rod end braces (Barbie Chairs) onto the front and rear rod ends of the upper trailing arms with the axle mounts resting on the axle. (Figure 19) These braces will support the rod end connection while welding. These rod end braces align the rod ends in the tabs to get the mounts tack welded and should be removed before finish welding to prevent melting the braces.
25. Double-check that your axle is 4-3/4” from the bottom of the frame, centered within the frame rails, and your pinion angle is still set to 0 degrees before tack welding the upper trailing arm mounts to the axle. (Figure 20)
26. Double-check all measurements again before removing the axle from the vehicle for final welding.(Figure 21)
27. Weld the outside edges of the upper trailing arm brackets to the axle tubes. It is recommended not to fully weld the inner tabs as to not introduce an excessive amount of heat into the tab.
28. Coat the axle as desired to prevent future corrosion.
29. Install the included block-off plates to the factory upper shock mounts using the included 5/16 x ¾” bolts and washers. Torque to 18 lb. ft. These plates will prevent road debris from entering the trunk. (Figure 22)
30. Reinstall the axle into the vehicle and reconnect the following:
  * CONNECTION| TORQUE SPEC

---|---
Lower Trailing Arm to Axle| 75 lb. ft.
Lower Shock Mount to Axle| 50 lb. ft.
Upper Trailing Arm to Axle| 75 lb. ft.
31. Reinstall the brake lines and bleed the system. 32. Reinstall the drive shaft. 33. Refer to the coil-over assembly instructions included with the shocks. 34. Adjust the spring seats on the coil-over shocks so that 2” of threads are under the adjustment collars. This will be a good initial setting to set the car down and check the ride height. Re-adjust the collars with the weight off of the car to the desired ride height before tightening the lower locking collar into the spring seat collar. At final ride height the shock should measure 13.25” to 14.5”, measured center/center on the mounting bolts. Set the shock adjustment knob(s) for the intended driving to be done only after the final ride height is set. 35. Install and modify (as needed) the exhaust system. 36. Double-check all work. It’s a basic and overlooked practice that distinguishes the most effective builders from the rest.

TIRE WIDTH CLEARANCE

The OE wheel opening allows approximately 10” of tire clearance before the tires will contact the inner wheel well towards the front of the wheel well. Clearance to the QA1 lower trailing arm is approximately 13 ¼” and should easily accommodate 335mm tires on a car with modified wheel tubs.

A professional four-wheel alignment is required before driving the vehicle.

Shock Valving Adjustments

READ ALL INSTRUCTIONS CAREFULLY AND THOROUGHLY PRIOR TO STARTING INSTALLATION. PRODUCTS THAT HAVE BEEN INSTALLED ARE NOT ELIGIBLE FOR RETURN. USE THE PROPER JACKING LOCATIONS. DEATH OR SERIOUS INJURY CAN RESULT IF INSTRUCTIONS ARE NOT CORRECTLY FOLLOWED. A GOOD CHASSIS MANUAL, AVAILABLE AT YOUR LOCAL PARTS STORE, MAY ALSO AID IN YOUR INSTALLATION.

DISCLAIMER / WARRANTY •

QA1 WARRANTS THAT THE PRODUCTS WILL BE FREE FROM DEFECTS IN MATERIAL AND WORKMANSHIP FOR ONE YEAR FROM THE DATE OF SALE TO THE ORIGINAL PURCHASER. QA1 MAKES NO OTHER WARRANTY OF ANY KIND, EXPRESS OR IMPLIED. QA1 SHALL HAVE NO OBLIGATION UNDER THE FOREGOING WARRANTY WHERE THE DEFECT IS THE RESULT OF IMPROPER OR ABNORMAL USE, YOUR NEGLIGENCE, VEHICLE ACCIDENT, IMPROPER OR INCORRECT INSTALLATION OR MAINTENANCE, NOR WHEN THE PRODUCT HAS BEEN REPAIRED OR ALTERED IN ANY WAY. QA1’S LIABILITY IN THE CASE OF DEFECTIVE PRODUCTS SUBJECT TO THE FOREGOING WARRANTY SHALL BE LIMITED TO THE REPAIR OR REPLACEMENT, AT QA1’S OPTION, OF THE DEFECTIVE PRODUCTS. THE USER UNDERSTANDS AND RECOGNIZES THAT RACING PARTS, SPECIALIZED STREET ROD EQUIPMENT, AND ALL PARTS AND SERVICES SOLD BY QA1 ARE EXPOSED TO MANY AND VARIED CONDITIONS DUE TO THE MANNER IN WHICH THEY ARE INSTALLED AND USED. QA1 SHALL BEAR NO LIABILITY FOR ANY LOSS, DAMAGE OR INJURY, EITHER TO A PERSON OR TO PROPERTY, RESULTING FROM THE INSTALLATION, DIRECT OR INDIRECT USE OF ANY QA1 PRODUCTS OR INABILITY BY THE BUYER TO DETERMINE PROPER USE OR APPLICATION OF QA1 PRODUCTS. WITH THE EXCEPTION OF THE LIMITED LIABILITY WARRANTY SET FORTH ABOVE, QA1 SHALL NOT BE LIABLE FOR ANY CLAIMS, DEMANDS, INJURIES, DAMAGES, ACTIONS, OR CAUSES OF ACTION WHATSOEVER TO BUYER ARISING OUT OF OR CONNECTED WITH THE USE OF ANY QA1 PRODUCTS. MOTORSPORTS ARE DANGEROUS; AS SUCH, NO WARRANTY OR REPRESENTATION IS MADE AS TO THE PRODUCT’S ABILITY TO PROTECT THE USER FROM INJURY OR DEATH. THE USER ASSUMES THAT RISK!

CONTACT INFORMATION

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